Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
BBA - Molecular Basis of Disease (v.1832, #5)
X-linked intellectual disability gene CUL4B targets Jab1/CSN5 for degradation and regulates bone morphogenetic protein signaling by Fengjuan He; Defen Lu; Baichun Jiang; Yan Wang; Qiao Liu; Qiji Liu; Changshun Shao; Xi Li; Yaoqin Gong (pp. 595-605).
Cullin 4B (CUL4B) is a scaffold protein involved in the assembly of cullin-RING ubiquitin ligase (E3) complexes. Contemporary reports have identified multiple mutations of CUL4B gene as being causally associated with X-linked intellectual disability (XLID). Identifying the specific protein substrates will help to better understand the physiological functions of CUL4B. The current study identified Jun activation domain-binding protein (Jab1/CSN5) in the COP9 signalosome (CSN) complex as a novel proteolytic target for the CUL4B ubiquitin ligase complex. The impaired degradation of Jab1 was observed in cells after RNAi-mediated CUL4B depletion. Integrity of DDB1-CUL4B-ROC1 was further demonstrated to be indispensable for the degradation of Jab1. In addition, the degradation of Jab1 is independent of CUL4A, a cullin family member closely related to CUL4B. In vitro and in vivo ubiquitination assays revealed that CUL4B promoted the polyubiquitination of Jab1. Interestingly, CUL4B-silenced cells were shown to exhibit abnormal upregulation of bone morphogenetic protein (BMP) signaling. Furthermore, in vivo studies of embryonic fibroblasts in Cul4b-deficient mice demonstrated Jab1 accumulation and increased activation of the BMP signaling pathway. Together, the current findings demonstrate the CUL4B E3 ubiquitin ligase plays a key role in targeting Jab1 for degradation, potentially revealing a previously undocumented mechanism for regulation of the BMP signaling pathway involved with the CUL4B-based E3 complex. This observation may provide novel insights into the molecular mechanisms underlying CUL4B-associated XLID pathogenesis.► Mutations of the CUL4B gene are linked to X-linked intellectual disability. ► Jab1 is identified as a specific substrate for CUL4B E3 ligase. ► Accumulated Jab1 in response to CUL4B deficiency enhances BMP signaling.
Keywords: Abbreviations; CUL4B; Cullin 4B; XLID; X-linked intellectual disability; Jab1; Jun activation domain-binding protein; CSN; the constitutive photomorphogenic-9 (COP9) signalosome; BMP; bone morphogenetic protein; CRLs; the cullin-RING ubiquitin ligases; DWD; DDB1-binding WD40; ROS; reactive oxygen species; JAMM; Mpr1-Pad1-N-terminal (MPN) domain metalloenzyme motif; Smurf; Smad ubiquitin regulatory factor; MEF; mouse embryonic fibroblasts; siRNA; small interfering RNA; CHX; cycloheximideCUL4B; Intellectual disability; Jab1; BMP signaling
X-linked intellectual disability gene CUL4B targets Jab1/CSN5 for degradation and regulates bone morphogenetic protein signaling by Fengjuan He; Defen Lu; Baichun Jiang; Yan Wang; Qiao Liu; Qiji Liu; Changshun Shao; Xi Li; Yaoqin Gong (pp. 595-605).
Cullin 4B (CUL4B) is a scaffold protein involved in the assembly of cullin-RING ubiquitin ligase (E3) complexes. Contemporary reports have identified multiple mutations of CUL4B gene as being causally associated with X-linked intellectual disability (XLID). Identifying the specific protein substrates will help to better understand the physiological functions of CUL4B. The current study identified Jun activation domain-binding protein (Jab1/CSN5) in the COP9 signalosome (CSN) complex as a novel proteolytic target for the CUL4B ubiquitin ligase complex. The impaired degradation of Jab1 was observed in cells after RNAi-mediated CUL4B depletion. Integrity of DDB1-CUL4B-ROC1 was further demonstrated to be indispensable for the degradation of Jab1. In addition, the degradation of Jab1 is independent of CUL4A, a cullin family member closely related to CUL4B. In vitro and in vivo ubiquitination assays revealed that CUL4B promoted the polyubiquitination of Jab1. Interestingly, CUL4B-silenced cells were shown to exhibit abnormal upregulation of bone morphogenetic protein (BMP) signaling. Furthermore, in vivo studies of embryonic fibroblasts in Cul4b-deficient mice demonstrated Jab1 accumulation and increased activation of the BMP signaling pathway. Together, the current findings demonstrate the CUL4B E3 ubiquitin ligase plays a key role in targeting Jab1 for degradation, potentially revealing a previously undocumented mechanism for regulation of the BMP signaling pathway involved with the CUL4B-based E3 complex. This observation may provide novel insights into the molecular mechanisms underlying CUL4B-associated XLID pathogenesis.► Mutations of the CUL4B gene are linked to X-linked intellectual disability. ► Jab1 is identified as a specific substrate for CUL4B E3 ligase. ► Accumulated Jab1 in response to CUL4B deficiency enhances BMP signaling.
Keywords: Abbreviations; CUL4B; Cullin 4B; XLID; X-linked intellectual disability; Jab1; Jun activation domain-binding protein; CSN; the constitutive photomorphogenic-9 (COP9) signalosome; BMP; bone morphogenetic protein; CRLs; the cullin-RING ubiquitin ligases; DWD; DDB1-binding WD40; ROS; reactive oxygen species; JAMM; Mpr1-Pad1-N-terminal (MPN) domain metalloenzyme motif; Smurf; Smad ubiquitin regulatory factor; MEF; mouse embryonic fibroblasts; siRNA; small interfering RNA; CHX; cycloheximideCUL4B; Intellectual disability; Jab1; BMP signaling
The role of proton dynamics in the development and maintenance of multidrug resistance in cancer by Chloë Daniel; Charlotte Bell; Christopher Burton; Salvador Harguindey; Stephan J. Reshkin; Cyril Rauch (pp. 606-617).
With a projected 382.4 per 100,000 people expected to suffer from some form of malignant neoplasm in 2015, improving treatment is an essential focus of cancer research today. Multi-drug resistance (MDR) is the leading cause of chemotherapeutic failure in the treatment of cancer, the term denoting a characteristic of the disease-causing agent to avoid damage by drugs designed to bring about their destruction. MDR is also characterised by a reversal of the pH gradient across cell membranes leading to an acidification of the outer milieu and an alkalinisation of the cytosol that is maintained by the proton pump vacuolar-type ATPase (V-ATPase) and the proton transporters: Na+/H+ exchanger (NHE1), Monocarboxylate Transporters (MCTs), Carbonic anhydrases (CAs) (mainly CA-IX), adenosinetriphosphate synthase, Na+/HCO3− co-transporter and the Cl−/HCO3−exchanger. This review aims to give an introduction to MDR. It will begin with an explanation for what MDR actually is and go on to look at the proposed mechanisms by which a state of drug resistance is achieved. The role of proton-pumps in creating an acidic extracellular pH and alkaline cytosol, as well as key biomechanical processes within the cell membrane itself, will be used to explain how drug resistance can be sustained.Basic schematic illustrating the some of the complex inter-relationships of mechanisms of malignant transformation and tumourigenesis described thus far, which play a critical role in the development of resistance. Note in particular the complete cycle of hypoxia and malignant progression (red arrows) is described fully by Höckel [151]. Elsewhere, it is evident that inhibition of only one factor may prove unsuccessful due to the number of alternative routes available for disease progression.Display Omitted► By definition metastatic cancers do not respond to drug treatments. ► Lack of drugs response is associated with over expression of membrane pumps involved in the efflux of drug. ► pH efflux is also central to cancer metabolism and metastasis and a connection may exist between drug/pH efflux. ► It is membrane biophysical structure that allows the interaction between metabolism and drug resistance in cancer. ► The modulation of metastasis requires new therapeutic strategies targeting the membrane of cancer cells.
Keywords: Multidrug resistance; Proton pump; Cancer; Drug efflux; Membrane physical biology
The role of proton dynamics in the development and maintenance of multidrug resistance in cancer by Chloë Daniel; Charlotte Bell; Christopher Burton; Salvador Harguindey; Stephan J. Reshkin; Cyril Rauch (pp. 606-617).
With a projected 382.4 per 100,000 people expected to suffer from some form of malignant neoplasm in 2015, improving treatment is an essential focus of cancer research today. Multi-drug resistance (MDR) is the leading cause of chemotherapeutic failure in the treatment of cancer, the term denoting a characteristic of the disease-causing agent to avoid damage by drugs designed to bring about their destruction. MDR is also characterised by a reversal of the pH gradient across cell membranes leading to an acidification of the outer milieu and an alkalinisation of the cytosol that is maintained by the proton pump vacuolar-type ATPase (V-ATPase) and the proton transporters: Na+/H+ exchanger (NHE1), Monocarboxylate Transporters (MCTs), Carbonic anhydrases (CAs) (mainly CA-IX), adenosinetriphosphate synthase, Na+/HCO3− co-transporter and the Cl−/HCO3−exchanger. This review aims to give an introduction to MDR. It will begin with an explanation for what MDR actually is and go on to look at the proposed mechanisms by which a state of drug resistance is achieved. The role of proton-pumps in creating an acidic extracellular pH and alkaline cytosol, as well as key biomechanical processes within the cell membrane itself, will be used to explain how drug resistance can be sustained.Basic schematic illustrating the some of the complex inter-relationships of mechanisms of malignant transformation and tumourigenesis described thus far, which play a critical role in the development of resistance. Note in particular the complete cycle of hypoxia and malignant progression (red arrows) is described fully by Höckel [151]. Elsewhere, it is evident that inhibition of only one factor may prove unsuccessful due to the number of alternative routes available for disease progression.Display Omitted► By definition metastatic cancers do not respond to drug treatments. ► Lack of drugs response is associated with over expression of membrane pumps involved in the efflux of drug. ► pH efflux is also central to cancer metabolism and metastasis and a connection may exist between drug/pH efflux. ► It is membrane biophysical structure that allows the interaction between metabolism and drug resistance in cancer. ► The modulation of metastasis requires new therapeutic strategies targeting the membrane of cancer cells.
Keywords: Multidrug resistance; Proton pump; Cancer; Drug efflux; Membrane physical biology
Pro-inflammatory cytokines modulate iron regulatory protein 1 expression and iron transportation through reactive oxygen/nitrogen species production in ventral mesencephalic neurons by Jia Wang; Ning Song; Hong Jiang; Jun Wang; Junxia Xie (pp. 618-625).
Both inflammatory processes associated with microglia activation and abnormal iron deposit in dopaminergic neurons are involved in the pathogenesis of Parkinson's disease (PD). However, the relationship between neuroinflammation and iron accumulation was not fully elucidated. In the present study, we aimed to investigate whether the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) released by microglia, could affect cellular iron transportation in primary cultured ventral mesencephalic (VM) neurons. The results showed that IL-1β or TNF-α treatment led to increased ferrous iron influx and decreased iron efflux in these cells, due to the upregulation of divalent metal transporter 1 with the iron response element (DMT1+IRE) and downregulation of ferroportin1 (FPN1). Increased levels of iron regulatory protein 1 (IRP1), transferrin receptor 1 (TfR1) and hepcidin were also observed in IL-1β or TNF-α treated VM neurons. IRP1 upregulation could be fully abolished by co-administration of radical scavenger N-acetyl-l-cysteine and inducible NO synthetase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride. Further experiments demonstrated that IL-1β and TNF-α release was remarkably enhanced by iron load in activated microglia triggered by lipopolysaccharide or 1-methyl-4-phenylpyridinium (MPP+). In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice, salicylate application could not block DMT1+IRE upregulation in dopaminergic neurons of substantia nigra. These results suggested that IL-1β and TNF-α released by microglia, especially under the condition of iron load, might contribute to iron accumulation in VM neurons by upregulating IRP1 and hepcidin levels through reactive oxygen/nitrogen species production. This might provide a new insight into unraveling that microglia might aggravate this iron mediated neuropathologies in PD.Display Omitted► IL-1β and TNF-α modulate iron transportation in ventral mesencephalic neurons. ► Regulation of iron transporters by IL-1β or TNF-α was mediated by IRP1. ► Reactive oxygen/nitrogen species account for IRP1 upregulation. ► IL-1β and TNF-α release was enhanced on the condition of iron load.
Keywords: Abbreviations; DMT1; divalent metal transporter 1; FAC; ferric ammonium citrate; iNOS; inducible NO synthetase; IL-1β; interleukin-1β; FPN1; ferroportin 1; IRP; iron regulatory protein; IRE; iron responsive element; LPS; lipopolysaccharide; MPP; +; 1-methyl-4-phenylpyridinium; MPTP; 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NAC; N; -acetyl-; l; -cysteine; NO; nitric oxide; L-NAME; N; ω; -nitro-; l; -arginine methyl ester hydrochloride; PD; Parkinson's disease; ROS; reactive oxygen species; SN; substantia nigra; TfR1; transferrin receptor 1; TNF-α; tumor necrosis factor-α; TH; tyrosine hydroxylase; VM; ventral mesencephalonInterleukin-1β; Tumor necrosis factor-α; Iron; Iron regulatory protein 1; Microglia; Neuron
Pro-inflammatory cytokines modulate iron regulatory protein 1 expression and iron transportation through reactive oxygen/nitrogen species production in ventral mesencephalic neurons by Jia Wang; Ning Song; Hong Jiang; Jun Wang; Junxia Xie (pp. 618-625).
Both inflammatory processes associated with microglia activation and abnormal iron deposit in dopaminergic neurons are involved in the pathogenesis of Parkinson's disease (PD). However, the relationship between neuroinflammation and iron accumulation was not fully elucidated. In the present study, we aimed to investigate whether the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) released by microglia, could affect cellular iron transportation in primary cultured ventral mesencephalic (VM) neurons. The results showed that IL-1β or TNF-α treatment led to increased ferrous iron influx and decreased iron efflux in these cells, due to the upregulation of divalent metal transporter 1 with the iron response element (DMT1+IRE) and downregulation of ferroportin1 (FPN1). Increased levels of iron regulatory protein 1 (IRP1), transferrin receptor 1 (TfR1) and hepcidin were also observed in IL-1β or TNF-α treated VM neurons. IRP1 upregulation could be fully abolished by co-administration of radical scavenger N-acetyl-l-cysteine and inducible NO synthetase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride. Further experiments demonstrated that IL-1β and TNF-α release was remarkably enhanced by iron load in activated microglia triggered by lipopolysaccharide or 1-methyl-4-phenylpyridinium (MPP+). In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice, salicylate application could not block DMT1+IRE upregulation in dopaminergic neurons of substantia nigra. These results suggested that IL-1β and TNF-α released by microglia, especially under the condition of iron load, might contribute to iron accumulation in VM neurons by upregulating IRP1 and hepcidin levels through reactive oxygen/nitrogen species production. This might provide a new insight into unraveling that microglia might aggravate this iron mediated neuropathologies in PD.Display Omitted► IL-1β and TNF-α modulate iron transportation in ventral mesencephalic neurons. ► Regulation of iron transporters by IL-1β or TNF-α was mediated by IRP1. ► Reactive oxygen/nitrogen species account for IRP1 upregulation. ► IL-1β and TNF-α release was enhanced on the condition of iron load.
Keywords: Abbreviations; DMT1; divalent metal transporter 1; FAC; ferric ammonium citrate; iNOS; inducible NO synthetase; IL-1β; interleukin-1β; FPN1; ferroportin 1; IRP; iron regulatory protein; IRE; iron responsive element; LPS; lipopolysaccharide; MPP; +; 1-methyl-4-phenylpyridinium; MPTP; 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NAC; N; -acetyl-; l; -cysteine; NO; nitric oxide; L-NAME; N; ω; -nitro-; l; -arginine methyl ester hydrochloride; PD; Parkinson's disease; ROS; reactive oxygen species; SN; substantia nigra; TfR1; transferrin receptor 1; TNF-α; tumor necrosis factor-α; TH; tyrosine hydroxylase; VM; ventral mesencephalonInterleukin-1β; Tumor necrosis factor-α; Iron; Iron regulatory protein 1; Microglia; Neuron
Molecular mechanisms beyond glucose transport in diabetes-related male infertility by M.G. Alves; A.D. Martins; L. Rato; P.I. Moreira; S. Socorro; P.F. Oliveira (pp. 626-635).
Diabetes mellitus (DM) is one of the greatest public health threats in modern societies. Although during a few years it was suggested that DM had no significant effect in male reproductive function, this view has been challenged in recent years. The increasing incidence of DM worldwide will inevitably result in a higher prevalence of this pathology in men of reproductive age and subfertility or infertility associated with DM is expected to dramatically rise in upcoming years. From a clinical perspective, the evaluation of semen parameters, as well as spermatozoa deoxyribonucleic acid (DNA) integrity, are often studied due to their direct implications in natural and assisted conception. Nevertheless, recent studies based on the molecular mechanisms beyond glucose transport in testicular cells provide new insights in DM-induced alterations in male reproductive health. Testicular cells have their own glucose sensing machinery that react to hormonal fluctuations and have several mechanisms to counteract hyper- and hypoglycemic events. Moreover, the metabolic cooperation between testicular cells is crucial for normal spermatogenesis. Sertoli cells (SCs), which are the main components of blood–testis barrier, are not only responsible for the physical support of germ cells but also for lactate production that is then metabolized by the developing germ cells. Any alteration in this tied metabolic cooperation may have a dramatic consequence in male fertility potential. Therefore, we present an overview of the clinical significance of DM in the male reproductive health with emphasis on the molecular mechanisms beyond glucose fluctuation and transport in testicular cells.► The increasing incidence of diabetes (DM) is affecting men in reproductive age. ► DM associated male subfertility/infertility will dramatically rise. ► DM may compromise the metabolic cooperation between testicular cells. ► Insulin (de)regulation is a major player in male reproductive health. ► Effects of DM on testicular metabolic pathways have been somewhat neglected.
Keywords: Diabetes; Insulin; Male infertility; Oxidative stress; Testicular metabolism
Molecular mechanisms beyond glucose transport in diabetes-related male infertility by M.G. Alves; A.D. Martins; L. Rato; P.I. Moreira; S. Socorro; P.F. Oliveira (pp. 626-635).
Diabetes mellitus (DM) is one of the greatest public health threats in modern societies. Although during a few years it was suggested that DM had no significant effect in male reproductive function, this view has been challenged in recent years. The increasing incidence of DM worldwide will inevitably result in a higher prevalence of this pathology in men of reproductive age and subfertility or infertility associated with DM is expected to dramatically rise in upcoming years. From a clinical perspective, the evaluation of semen parameters, as well as spermatozoa deoxyribonucleic acid (DNA) integrity, are often studied due to their direct implications in natural and assisted conception. Nevertheless, recent studies based on the molecular mechanisms beyond glucose transport in testicular cells provide new insights in DM-induced alterations in male reproductive health. Testicular cells have their own glucose sensing machinery that react to hormonal fluctuations and have several mechanisms to counteract hyper- and hypoglycemic events. Moreover, the metabolic cooperation between testicular cells is crucial for normal spermatogenesis. Sertoli cells (SCs), which are the main components of blood–testis barrier, are not only responsible for the physical support of germ cells but also for lactate production that is then metabolized by the developing germ cells. Any alteration in this tied metabolic cooperation may have a dramatic consequence in male fertility potential. Therefore, we present an overview of the clinical significance of DM in the male reproductive health with emphasis on the molecular mechanisms beyond glucose fluctuation and transport in testicular cells.► The increasing incidence of diabetes (DM) is affecting men in reproductive age. ► DM associated male subfertility/infertility will dramatically rise. ► DM may compromise the metabolic cooperation between testicular cells. ► Insulin (de)regulation is a major player in male reproductive health. ► Effects of DM on testicular metabolic pathways have been somewhat neglected.
Keywords: Diabetes; Insulin; Male infertility; Oxidative stress; Testicular metabolism
Specific functioning of Cav3.2 T-type calcium and TRPV1 channels under different types of STZ-diabetic neuropathy by Eugen V. Khomula; Viacheslav Y. Viatchenko-Karpinski; Anya L. Borisyuk; Dmytro E. Duzhyy; Pavel V. Belan; Nana V. Voitenko (pp. 636-649).
Streptozotocin (STZ)-induced type 1 diabetes in rats leads to the development of peripheral diabetic neuropathy (PDN) manifested as thermal hyperalgesia at early stages (4th week) followed by hypoalgesia after 8weeks of diabetes development. Here we found that 6–7week STZ-diabetic rats developed either thermal hyper- (18%), hypo- (25%) or normalgesic (57%) types of PDN. These developmentally similar diabetic rats were studied in order to analyze mechanisms potentially underlying different thermal nociception. The proportion of IB4-positive capsaicin-sensitive small DRG neurons, strongly involved in thermal nociception, was not altered under different types of PDN implying differential changes at cellular and molecular level. We further focused on properties of T-type calcium and TRPV1 channels, which are known to be involved in Ca2+ signaling and pathological nociception. Indeed, TRPV1-mediated signaling in these neurons was downregulated under hypo- and normalgesia and upregulated under hyperalgesia. A complex interplay between diabetes-induced changes in functional expression of Cav3.2 T-type calcium channels and depolarizing shift of their steady-state inactivation resulted in upregulation of these channels under hyper- and normalgesia and their downregulation under hypoalgesia. As a result, T-type window current was increased by several times under hyperalgesia partially underlying the increased resting [Ca2+]i observed in the hyperalgesic rats. At the same time Cav3.2-dependent Ca2+ signaling was upregulated in all types of PDN. These findings indicate that alterations in functioning of Cav3.2 T-type and TRPV1 channels, specific for each type of PDN, may underlie the variety of pain syndromes induced by type 1 diabetes.► PDN affects Cav3.2 and TRPV1 channels in small DRG neurons. ► Hyperalgesic PDN upregulated both Cav3.2 and TRPV1 channels. ► Hypoalgesic PDN downregulated Cav3.2 and TRPV1 channels. ► Upregulation of Cav3.2 and downregulation of TRPV1 channels under normalgesic PDN ► Increased T-type window current contributes to the resting [Ca2+]i in diabetes.
Keywords: Abbreviations; [Ca; 2; +; ]; i; cytosolic Ca; 2; +; concentration; DRG; dorsal root ganglia; HMP; holding membrane potential; IB4; isolectin B; 4; LVA/HVA; low/high voltage activated; NTCN; nonpeptidergic thermal C-type nociceptive (neurons); PCD; peak current density; PDN; peripheral diabetic neuropathy; PWL; paw withdrawal latency; SSI; steady-state inactivation; STZ; streptozotocin; T-PCD; T-type PCD; TPS; thermal pain sensitivityDiabetes; PDN; DRG; Patch clamp; VOCC; Calcium imaging
Specific functioning of Cav3.2 T-type calcium and TRPV1 channels under different types of STZ-diabetic neuropathy by Eugen V. Khomula; Viacheslav Y. Viatchenko-Karpinski; Anya L. Borisyuk; Dmytro E. Duzhyy; Pavel V. Belan; Nana V. Voitenko (pp. 636-649).
Streptozotocin (STZ)-induced type 1 diabetes in rats leads to the development of peripheral diabetic neuropathy (PDN) manifested as thermal hyperalgesia at early stages (4th week) followed by hypoalgesia after 8weeks of diabetes development. Here we found that 6–7week STZ-diabetic rats developed either thermal hyper- (18%), hypo- (25%) or normalgesic (57%) types of PDN. These developmentally similar diabetic rats were studied in order to analyze mechanisms potentially underlying different thermal nociception. The proportion of IB4-positive capsaicin-sensitive small DRG neurons, strongly involved in thermal nociception, was not altered under different types of PDN implying differential changes at cellular and molecular level. We further focused on properties of T-type calcium and TRPV1 channels, which are known to be involved in Ca2+ signaling and pathological nociception. Indeed, TRPV1-mediated signaling in these neurons was downregulated under hypo- and normalgesia and upregulated under hyperalgesia. A complex interplay between diabetes-induced changes in functional expression of Cav3.2 T-type calcium channels and depolarizing shift of their steady-state inactivation resulted in upregulation of these channels under hyper- and normalgesia and their downregulation under hypoalgesia. As a result, T-type window current was increased by several times under hyperalgesia partially underlying the increased resting [Ca2+]i observed in the hyperalgesic rats. At the same time Cav3.2-dependent Ca2+ signaling was upregulated in all types of PDN. These findings indicate that alterations in functioning of Cav3.2 T-type and TRPV1 channels, specific for each type of PDN, may underlie the variety of pain syndromes induced by type 1 diabetes.► PDN affects Cav3.2 and TRPV1 channels in small DRG neurons. ► Hyperalgesic PDN upregulated both Cav3.2 and TRPV1 channels. ► Hypoalgesic PDN downregulated Cav3.2 and TRPV1 channels. ► Upregulation of Cav3.2 and downregulation of TRPV1 channels under normalgesic PDN ► Increased T-type window current contributes to the resting [Ca2+]i in diabetes.
Keywords: Abbreviations; [Ca; 2; +; ]; i; cytosolic Ca; 2; +; concentration; DRG; dorsal root ganglia; HMP; holding membrane potential; IB4; isolectin B; 4; LVA/HVA; low/high voltage activated; NTCN; nonpeptidergic thermal C-type nociceptive (neurons); PCD; peak current density; PDN; peripheral diabetic neuropathy; PWL; paw withdrawal latency; SSI; steady-state inactivation; STZ; streptozotocin; T-PCD; T-type PCD; TPS; thermal pain sensitivityDiabetes; PDN; DRG; Patch clamp; VOCC; Calcium imaging
Branched-chain amino acids influence the immune properties of microglial cells and their responsiveness to pro-inflammatory signals by Roberta De Simone; Federica Vissicchio; Cecilia Mingarelli; Chiara De Nuccio; Sergio Visentin; Maria Antonietta Ajmone-Cat; Luisa Minghetti (pp. 650-659).
The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids involved in several important brain functions. Although commonly used as nutritional supplements, excessive intake of BCAAs might favour the establishment of neurotoxic conditions as indicated by the severe neurological symptoms characterising inherited disorders of BCAA catabolism such as maple syrup urine disease (MSUD). Recent evidence indicates that BCAAs induce excitotoxicity through mechanisms that require the presence of astrocytes. In the present study, we evaluated the effects of BCAAs on microglia, the main immune cells of the brain. As an experimental model we used primary microglial cells harvested from mixed glial cultures that had been kept in normal or high BCAA medium (H-BCAA). We show that H-BCAA microglial cells exhibit a peculiar phenotype characterized by a partial skewing toward the M2 state, with enhanced IL-10 expression and phagocytic activity but also increased free radical generation and decreased neuroprotective functions. We suggest that such an intermediate M1/M2 phenotype might result in a less efficient microglial response, which would promote the establishment of a low grade chronic inflammation and increase the likelihood of neurodegeneration. Although based on in vitro evidence, our study adds on to an increasing literature indicating that the increasing use of dietary integrators might deserve consideration for the possible drawbacks. In addition to excitotoxicity, the altered immune profile of microglia might represent a further mechanism by which BCAAs might turn into toxicants and facilitate neurodegeneration.► BCAAs cross the blood–brain barrier and influence several important brain functions. ► They are used as dietary integrators in elderly, neurological patients and athletes. ► High BCAAs favour astrocyte-dependent neurotoxicity by NMDA receptor activation. ► High BCAAs influence gene expression and immune properties of microglial cells. ► High BCAAs may promote low grade chronic inflammation favouring neurodegeneration.
Keywords: Abbreviations; 15-F2t-IsoP; 15-F; 2t; -isoprostane; ADP; adenosine 5ʹ-diphosphate; Arg-1; arginase-1; BCAAs; branched-chain amino acids; BME; basal Eagle's medium; IGF-1; insulin-like growth factor-1; IL; interleukin; iNOS; inducible nitric oxide synthase; KPBS; potassium-PBS; LPS; lipopolysaccharide; mMP; mitochondrial membrane potential; MRC-1; mannose receptor; MSUD; maple syrup urine disease; mTOR; mammalian target of rapamycin; NO; nitric oxide; PBS; phosphate-buffered saline; PFA; paraformaldehyde; TMRE; tetramethylrhodamine ethyl ester perchlorate; TNF-α; tumor necrosis factor-α; UDP; uridine 5ʹ-diphosphateBrain macrophages; Microglial activation; M1 phenotype; M2 phenotype; BCAA; Neurodegeneration
Branched-chain amino acids influence the immune properties of microglial cells and their responsiveness to pro-inflammatory signals by Roberta De Simone; Federica Vissicchio; Cecilia Mingarelli; Chiara De Nuccio; Sergio Visentin; Maria Antonietta Ajmone-Cat; Luisa Minghetti (pp. 650-659).
The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids involved in several important brain functions. Although commonly used as nutritional supplements, excessive intake of BCAAs might favour the establishment of neurotoxic conditions as indicated by the severe neurological symptoms characterising inherited disorders of BCAA catabolism such as maple syrup urine disease (MSUD). Recent evidence indicates that BCAAs induce excitotoxicity through mechanisms that require the presence of astrocytes. In the present study, we evaluated the effects of BCAAs on microglia, the main immune cells of the brain. As an experimental model we used primary microglial cells harvested from mixed glial cultures that had been kept in normal or high BCAA medium (H-BCAA). We show that H-BCAA microglial cells exhibit a peculiar phenotype characterized by a partial skewing toward the M2 state, with enhanced IL-10 expression and phagocytic activity but also increased free radical generation and decreased neuroprotective functions. We suggest that such an intermediate M1/M2 phenotype might result in a less efficient microglial response, which would promote the establishment of a low grade chronic inflammation and increase the likelihood of neurodegeneration. Although based on in vitro evidence, our study adds on to an increasing literature indicating that the increasing use of dietary integrators might deserve consideration for the possible drawbacks. In addition to excitotoxicity, the altered immune profile of microglia might represent a further mechanism by which BCAAs might turn into toxicants and facilitate neurodegeneration.► BCAAs cross the blood–brain barrier and influence several important brain functions. ► They are used as dietary integrators in elderly, neurological patients and athletes. ► High BCAAs favour astrocyte-dependent neurotoxicity by NMDA receptor activation. ► High BCAAs influence gene expression and immune properties of microglial cells. ► High BCAAs may promote low grade chronic inflammation favouring neurodegeneration.
Keywords: Abbreviations; 15-F2t-IsoP; 15-F; 2t; -isoprostane; ADP; adenosine 5ʹ-diphosphate; Arg-1; arginase-1; BCAAs; branched-chain amino acids; BME; basal Eagle's medium; IGF-1; insulin-like growth factor-1; IL; interleukin; iNOS; inducible nitric oxide synthase; KPBS; potassium-PBS; LPS; lipopolysaccharide; mMP; mitochondrial membrane potential; MRC-1; mannose receptor; MSUD; maple syrup urine disease; mTOR; mammalian target of rapamycin; NO; nitric oxide; PBS; phosphate-buffered saline; PFA; paraformaldehyde; TMRE; tetramethylrhodamine ethyl ester perchlorate; TNF-α; tumor necrosis factor-α; UDP; uridine 5ʹ-diphosphateBrain macrophages; Microglial activation; M1 phenotype; M2 phenotype; BCAA; Neurodegeneration
Protective effects of lipocalin-2 ( LCN2) in acute liver injury suggest a novel function in liver homeostasis by Erawan Borkham-Kamphorst; Eddy van de Leur; Henning W. Zimmermann; Karlin Raja Karlmark; Lidia Tihaa; Ute Haas; Frank Tacke; Thorsten Berger; Tak W. Mak; Ralf Weiskirchen (pp. 660-673).
Lipocalin-2 is expressed under pernicious conditions such as intoxication, infection, inflammation and other forms of cellular stress. Experimental liver injury induces rapid and sustained LCN2 production by injured hepatocytes. However, the precise biological function of LCN2 in liver is still unknown. In this study, LCN2−/− mice were exposed to short term application of CCl4, lipopolysaccharide and Concanavalin A, or subjected to bile duct ligation. Subsequent injuries were assessed by liver function analysis, qRT-PCR for chemokine and cytokine expression, liver tissue Western blot, histology and TUNEL assay. Serum LCN2 levels from patients suffering from liver disease were assessed and evaluated. Acute CCl4 intoxication showed increased liver damage in LCN2−/− mice indicated by higher levels of aminotransferases, and increased expression of inflammatory cytokines and chemokines such as IL-1β, IL-6, TNF-α and MCP-1/CCL2, resulting in sustained activation of STAT1, STAT3 and JNK pathways. Hepatocytes of LCN2−/− mice showed lipid droplet accumulation and increased apoptosis. Hepatocyte apoptosis was confirmed in the Concanavalin A and lipopolysaccharide models. In chronic models (4weeks bile duct ligation or 8weeks CCl4 application), LCN2−/− mice showed slightly increased fibrosis compared to controls. Interestingly, serum LCN2 levels in diseased human livers were significantly higher compared to controls, but no differences were observed between cirrhotic and non-cirrhotic patients. Upregulation of LCN2 is a reliable indicator of liver damage and has significant hepato-protective effect in acute liver injury. LCN2 levels provide no correlation to the degree of liver fibrosis but show significant positive correlation to inflammation instead.► Upregulation of LCN2 is a reliable indicator of liver damage. ► LCN2 has significant hepato-protective effects in acute liver injury. ► LCN2 deficient mice show increased expression of inflammatory mediators. ► LCN2 deficient mice show sustained activation of STAT1, STAT3 and JNK pathways. ►LCN2 is not correlated to hepatic fibrosis but correlates to inflammation.
Keywords: Abbreviations; HRS; hepatorenal syndrome; NGAL/LCN2; lipocalin 2 protein; LPS; lipopolysaccharide; ConA; Concanavalin A; BDL; bile duct ligation; MCP-1/CCL2; monocyte chemoattractant protein-1/C–C chemokine ligand-2Lipocalin; LCN2; NGAL; BDL; CCl; 4; Acute phase response
Protective effects of lipocalin-2 ( LCN2) in acute liver injury suggest a novel function in liver homeostasis by Erawan Borkham-Kamphorst; Eddy van de Leur; Henning W. Zimmermann; Karlin Raja Karlmark; Lidia Tihaa; Ute Haas; Frank Tacke; Thorsten Berger; Tak W. Mak; Ralf Weiskirchen (pp. 660-673).
Lipocalin-2 is expressed under pernicious conditions such as intoxication, infection, inflammation and other forms of cellular stress. Experimental liver injury induces rapid and sustained LCN2 production by injured hepatocytes. However, the precise biological function of LCN2 in liver is still unknown. In this study, LCN2−/− mice were exposed to short term application of CCl4, lipopolysaccharide and Concanavalin A, or subjected to bile duct ligation. Subsequent injuries were assessed by liver function analysis, qRT-PCR for chemokine and cytokine expression, liver tissue Western blot, histology and TUNEL assay. Serum LCN2 levels from patients suffering from liver disease were assessed and evaluated. Acute CCl4 intoxication showed increased liver damage in LCN2−/− mice indicated by higher levels of aminotransferases, and increased expression of inflammatory cytokines and chemokines such as IL-1β, IL-6, TNF-α and MCP-1/CCL2, resulting in sustained activation of STAT1, STAT3 and JNK pathways. Hepatocytes of LCN2−/− mice showed lipid droplet accumulation and increased apoptosis. Hepatocyte apoptosis was confirmed in the Concanavalin A and lipopolysaccharide models. In chronic models (4weeks bile duct ligation or 8weeks CCl4 application), LCN2−/− mice showed slightly increased fibrosis compared to controls. Interestingly, serum LCN2 levels in diseased human livers were significantly higher compared to controls, but no differences were observed between cirrhotic and non-cirrhotic patients. Upregulation of LCN2 is a reliable indicator of liver damage and has significant hepato-protective effect in acute liver injury. LCN2 levels provide no correlation to the degree of liver fibrosis but show significant positive correlation to inflammation instead.► Upregulation of LCN2 is a reliable indicator of liver damage. ► LCN2 has significant hepato-protective effects in acute liver injury. ► LCN2 deficient mice show increased expression of inflammatory mediators. ► LCN2 deficient mice show sustained activation of STAT1, STAT3 and JNK pathways. ►LCN2 is not correlated to hepatic fibrosis but correlates to inflammation.
Keywords: Abbreviations; HRS; hepatorenal syndrome; NGAL/LCN2; lipocalin 2 protein; LPS; lipopolysaccharide; ConA; Concanavalin A; BDL; bile duct ligation; MCP-1/CCL2; monocyte chemoattractant protein-1/C–C chemokine ligand-2Lipocalin; LCN2; NGAL; BDL; CCl; 4; Acute phase response
3,5-Diiodo-l-thyronine ameliorates diabetic nephropathy in streptozotocin-induced diabetic rats by Guoguo Shang; Pan Gao; Zhonghua Zhao; Qi Chen; Tao Jiang; Nong Zhang; Hui Li (pp. 674-684).
3, 5-Diiodothyronine (T2), a natural metabolite of triiodothyronine (T3) from deiodination pathway, can mimic biologic effects of T3 without inducing thyrotoxic effects. Recent studies revealed T3 acted as a protective factor against diabetic nephropathy (DN). Nevertheless, little is known about the effect of T2 on DN. This study was designed to investigate whether and how T2 affects experimental models of DN in vivo and in vitro. Administration of T2 was found to prevent significant decrease in SIRT1 protein expression and activity as well as increases in blood glucose, urine albumin excretion, matrix expansion, transforming growth factor-β1 expression, fibronectin and type IV collagen deposition in the diabetic kidney. Concordantly, similar effects of T2 were exhibited in the cultured rat mesangial cells (RMC) exposed to high glucose and that could be abolished by a known SIRT1 inhibitor, sirtinol. Moreover, enhanced NF-κB acetylation and JNK phosphorylation present in both diabetic rats and high glucose-treated RMC were distinctly dampened by T2. Collectively, these results suggested that T2 was a protective agent against renal damage in diabetic nephropathy, whose action involved regulation of SIRT1.► 3, 5-Diiodothyronine (T2) ameliorates renal damage in diabetic nephropathy. ► T2 reduces extracellular matrix synthesis in high glucose-treated mesangial cells. ► The mechanism of this salutary action of T2 is preservation of SIRT1 expression. ► T2-attenuated NF-κB acetylation contributes to its effects in diabetic conditions. ► T2 inhibits SIRT1 downregulation via inactivation of JNK in diabetic conditions.
Keywords: Abbreviations; T2; 3,5-diiodothyronine; T3; triiodothyronine; T4; thyroxine; SIRT1; Silent Information Regulator Transcript 1; HG; high glucose; NG; normal glucose; NF-κB; nuclear factor-κappa B; JNK; c-Jun N-terminal kinases; FN; fibronectin; COL IV; type IV collagen; TGF-β1; transforming growth factor beta 1; RMC; rat mesangial cell; DN; diabetic nephropathy3, 5-Diiodothyronine; Diabetic nephropathy; Mesangial cells; SIRT1; NF-κB; JNK
3,5-Diiodo-l-thyronine ameliorates diabetic nephropathy in streptozotocin-induced diabetic rats by Guoguo Shang; Pan Gao; Zhonghua Zhao; Qi Chen; Tao Jiang; Nong Zhang; Hui Li (pp. 674-684).
3, 5-Diiodothyronine (T2), a natural metabolite of triiodothyronine (T3) from deiodination pathway, can mimic biologic effects of T3 without inducing thyrotoxic effects. Recent studies revealed T3 acted as a protective factor against diabetic nephropathy (DN). Nevertheless, little is known about the effect of T2 on DN. This study was designed to investigate whether and how T2 affects experimental models of DN in vivo and in vitro. Administration of T2 was found to prevent significant decrease in SIRT1 protein expression and activity as well as increases in blood glucose, urine albumin excretion, matrix expansion, transforming growth factor-β1 expression, fibronectin and type IV collagen deposition in the diabetic kidney. Concordantly, similar effects of T2 were exhibited in the cultured rat mesangial cells (RMC) exposed to high glucose and that could be abolished by a known SIRT1 inhibitor, sirtinol. Moreover, enhanced NF-κB acetylation and JNK phosphorylation present in both diabetic rats and high glucose-treated RMC were distinctly dampened by T2. Collectively, these results suggested that T2 was a protective agent against renal damage in diabetic nephropathy, whose action involved regulation of SIRT1.► 3, 5-Diiodothyronine (T2) ameliorates renal damage in diabetic nephropathy. ► T2 reduces extracellular matrix synthesis in high glucose-treated mesangial cells. ► The mechanism of this salutary action of T2 is preservation of SIRT1 expression. ► T2-attenuated NF-κB acetylation contributes to its effects in diabetic conditions. ► T2 inhibits SIRT1 downregulation via inactivation of JNK in diabetic conditions.
Keywords: Abbreviations; T2; 3,5-diiodothyronine; T3; triiodothyronine; T4; thyroxine; SIRT1; Silent Information Regulator Transcript 1; HG; high glucose; NG; normal glucose; NF-κB; nuclear factor-κappa B; JNK; c-Jun N-terminal kinases; FN; fibronectin; COL IV; type IV collagen; TGF-β1; transforming growth factor beta 1; RMC; rat mesangial cell; DN; diabetic nephropathy3, 5-Diiodothyronine; Diabetic nephropathy; Mesangial cells; SIRT1; NF-κB; JNK
Prevention and reversal of hepatic steatosis with a high-protein diet in mice by Sonia C. Garcia-Caraballo; Tine M. Comhair; Fons Verheyen; Ingrid Gaemers; Frank G. Schaap; Sander M. Houten; Theodorus B.M. Hakvoort; Cornelis H.C. Dejong; Wouter H. Lamers; S. Eleonore Koehler (pp. 685-695).
The hallmark of NAFLD is steatosis of unknown etiology. We tested the effect of a high-protein (HP)22AA: arachidonic acid; Acac: acetyl-CoA carboxylase; Acox: acyl-coenzyme A oxidase; Akt: thymoma viral proto-oncogene 1 (a.k.a. PKB-protein kinase B); Alas1: aminolevulinic acid synthase 1; Arntl (a.k.a. Bmal1): aryl hydrocarbon receptor nuclear translocator-like protein; BCAA: branched-chain amino acids; BHB: β-hydroxybutyrate; ITGAM: Integrin-αM; Chop/Ddit3: C/EBP-homologous protein/DNA damage-inducible transcript 3 protein; Chrebp: carbohydrate-responsive element-binding protein; Cpt1: carnitine palmitoyltransferase 1; DHA: docosahexaenoic acid; eIF2α: eukaryotic translation–initiation factor 2α; Elovl: elongation of very long-chain fatty acids; en%: energy percent; EPA: eicosapentaenoic acid; Fasn: fatty acid synthase; Fgf21: fibroblast growth factor 21; FFA: free fatty acids; G6Pase: glucose-6-phosphatase; GCN2: general control nonrepressed 2; HF: high fat; HF/LPres: high fat, low protein restricted; HP: high protein; LF: low fat; LP: low protein; Mcp1: monocyte chemotactic protein 1; Mlxipl (a.k.a. Chrebp): Mlx-interacting protein-like; mAco: mitochondrial aconitase; mmBCFA: monomethyl branched-chain fatty acid; NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis; Nfil3: nuclear factor interleukin-3-regulated protein; NFκB: nuclear factor κB; Nr1d1 (a.k.a. rev-erbα): nuclear receptor subfamily 1, group D, member 1; PCK1: phospho enolpyruvate carboxykinase 1; PERK: protein kinase RNA-like endoplasmic reticulum kinase; Pgc1α: pparγ-coactivator1-α, PL: choline-containing phospholipids; Ppar: peroxisome proliferator-activated receptor; rs: Spearman correlation coefficient; Scd1: stearoyl-CoA desaturase 1; Srebf: sterol regulatory element-binding transcription factor; TC: total cholesterol; TG: triglycerides. diet on diet-induced steatosis in male C57BL/6 mice with and without pre-existing fatty liver. Mice were fed all combinations of semisynthetic low-fat (LF) or high-fat (HF) and low-protein (LP) or HP diets for 3weeks. To control for reduced energy intake by HF/HP-fed mice, a pair-fed HF/LP group was included. Reversibility of pre-existing steatosis was investigated by sequentially feeding HF/LP and HF/HP diets. HP-containing diets decreased hepatic lipids to ~40% of corresponding LP-containing diets, were more efficient in this respect than reducing energy intake to 80%, and reversed pre-existing diet-induced steatosis. Compared to LP-containing diets, mice fed HP-containing diets showed increased mitochondrial oxidative capacity (elevated Pgc1α, mAco, and Cpt1 mRNAs, complex-V protein, and decreased plasma free and short-chain acyl-carnitines, and [C0]/[C16+C18] carnitine ratio); increased gluconeogenesis and pyruvate cycling (increased PCK1 protein and fed plasma–glucose concentration without increased G6pase mRNA); reduced fatty-acid desaturation (decreased Scd1 expression and [C16:1n−7]/[C16:0] ratio) and increased long-chain PUFA elongation; a selective increase in plasma branched-chain amino acids; a decrease in cell stress (reduced phosphorylated eIF2α, and Fgf21 and Chop expression); and a trend toward less inflammation (lower Mcp1 and Cd11b expression and less phosphorylated NFκB). Conclusion: HP diets prevent and reverse steatosis independently of fat and carbohydrate intake more efficiently than a 20% reduction in energy intake. The effect appears to result from fuel-generated, highly distributed small, synergistic increases in lipid and BCAA catabolism, and a decrease in cell stress.► High-protein (HP) diets decrease steatosis with or without pre-existing fatty liver. ► HP diets reverse steatosis more efficiently than a 20% reduced energy intake. ► The anti-steatotic effect of HP diets is independent of fat and carbohydrate intake. ► HP diets induce small, synergistic increases in lipid and amino-acid catabolism. ► HP diets decrease cell stress.
Keywords: FGF21; ER-stress; NAFLD; Acyl-carnitines; High-fat diet
Prevention and reversal of hepatic steatosis with a high-protein diet in mice by Sonia C. Garcia-Caraballo; Tine M. Comhair; Fons Verheyen; Ingrid Gaemers; Frank G. Schaap; Sander M. Houten; Theodorus B.M. Hakvoort; Cornelis H.C. Dejong; Wouter H. Lamers; S. Eleonore Koehler (pp. 685-695).
The hallmark of NAFLD is steatosis of unknown etiology. We tested the effect of a high-protein (HP)22AA: arachidonic acid; Acac: acetyl-CoA carboxylase; Acox: acyl-coenzyme A oxidase; Akt: thymoma viral proto-oncogene 1 (a.k.a. PKB-protein kinase B); Alas1: aminolevulinic acid synthase 1; Arntl (a.k.a. Bmal1): aryl hydrocarbon receptor nuclear translocator-like protein; BCAA: branched-chain amino acids; BHB: β-hydroxybutyrate; ITGAM: Integrin-αM; Chop/Ddit3: C/EBP-homologous protein/DNA damage-inducible transcript 3 protein; Chrebp: carbohydrate-responsive element-binding protein; Cpt1: carnitine palmitoyltransferase 1; DHA: docosahexaenoic acid; eIF2α: eukaryotic translation–initiation factor 2α; Elovl: elongation of very long-chain fatty acids; en%: energy percent; EPA: eicosapentaenoic acid; Fasn: fatty acid synthase; Fgf21: fibroblast growth factor 21; FFA: free fatty acids; G6Pase: glucose-6-phosphatase; GCN2: general control nonrepressed 2; HF: high fat; HF/LPres: high fat, low protein restricted; HP: high protein; LF: low fat; LP: low protein; Mcp1: monocyte chemotactic protein 1; Mlxipl (a.k.a. Chrebp): Mlx-interacting protein-like; mAco: mitochondrial aconitase; mmBCFA: monomethyl branched-chain fatty acid; NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis; Nfil3: nuclear factor interleukin-3-regulated protein; NFκB: nuclear factor κB; Nr1d1 (a.k.a. rev-erbα): nuclear receptor subfamily 1, group D, member 1; PCK1: phospho enolpyruvate carboxykinase 1; PERK: protein kinase RNA-like endoplasmic reticulum kinase; Pgc1α: pparγ-coactivator1-α, PL: choline-containing phospholipids; Ppar: peroxisome proliferator-activated receptor; rs: Spearman correlation coefficient; Scd1: stearoyl-CoA desaturase 1; Srebf: sterol regulatory element-binding transcription factor; TC: total cholesterol; TG: triglycerides. diet on diet-induced steatosis in male C57BL/6 mice with and without pre-existing fatty liver. Mice were fed all combinations of semisynthetic low-fat (LF) or high-fat (HF) and low-protein (LP) or HP diets for 3weeks. To control for reduced energy intake by HF/HP-fed mice, a pair-fed HF/LP group was included. Reversibility of pre-existing steatosis was investigated by sequentially feeding HF/LP and HF/HP diets. HP-containing diets decreased hepatic lipids to ~40% of corresponding LP-containing diets, were more efficient in this respect than reducing energy intake to 80%, and reversed pre-existing diet-induced steatosis. Compared to LP-containing diets, mice fed HP-containing diets showed increased mitochondrial oxidative capacity (elevated Pgc1α, mAco, and Cpt1 mRNAs, complex-V protein, and decreased plasma free and short-chain acyl-carnitines, and [C0]/[C16+C18] carnitine ratio); increased gluconeogenesis and pyruvate cycling (increased PCK1 protein and fed plasma–glucose concentration without increased G6pase mRNA); reduced fatty-acid desaturation (decreased Scd1 expression and [C16:1n−7]/[C16:0] ratio) and increased long-chain PUFA elongation; a selective increase in plasma branched-chain amino acids; a decrease in cell stress (reduced phosphorylated eIF2α, and Fgf21 and Chop expression); and a trend toward less inflammation (lower Mcp1 and Cd11b expression and less phosphorylated NFκB). Conclusion: HP diets prevent and reverse steatosis independently of fat and carbohydrate intake more efficiently than a 20% reduction in energy intake. The effect appears to result from fuel-generated, highly distributed small, synergistic increases in lipid and BCAA catabolism, and a decrease in cell stress.► High-protein (HP) diets decrease steatosis with or without pre-existing fatty liver. ► HP diets reverse steatosis more efficiently than a 20% reduced energy intake. ► The anti-steatotic effect of HP diets is independent of fat and carbohydrate intake. ► HP diets induce small, synergistic increases in lipid and amino-acid catabolism. ► HP diets decrease cell stress.
Keywords: FGF21; ER-stress; NAFLD; Acyl-carnitines; High-fat diet
Corrigendum to “Metformin affects the circadian clock metabolic rhythms in a tissue-specific manner” Biochim. Biophys. Acta (1822)2012) 1796–1806
by Maayan Barnea; Liyan Haviva; Roee Gutman; Nava Chapnik; Zecharia Madar; Oren Froy (pp. 696-696).
Corrigendum to “Metformin affects the circadian clock metabolic rhythms in a tissue-specific manner” Biochim. Biophys. Acta (1822)2012) 1796–1806
by Maayan Barnea; Liyan Haviva; Roee Gutman; Nava Chapnik; Zecharia Madar; Oren Froy (pp. 696-696).