Muscle PARP1 inhibition extends lifespan through AMPKα PARylation and activation in Drosophila.

Poly(ADP-ribose) polymerase-1 (PARP1) has been reported to play an important role in longevity. Here, we showed that the knockdown of the PARP1 extended the lifespan of Drosophila, with particular emphasis on the skeletal muscle. The muscle-specific mutant Drosophila exhibited resistance to starvation and oxidative stress, as well as an increased ability to climb, with enhanced mitochondrial biogenesis and activity at an older age. Mechanistically, the inhibition of PARP1 increases the activity of AMP-activated protein kinase alpha (AMPKα) and mitochondrial turnover. PARP1 could interact with AMPKα and then regulate it via poly(ADP ribosyl)ation (PARylation) at residues E155 and E195. Double knockdown of PARP1 and AMPKα, specifically in muscle, could counteract the effects of PARP1 inhibition in Drosophila. Finally, we showed that increasing lifespan via maintaining mitochondrial network homeostasis required intact PTEN induced kinase 1 (PINK1). Taken together, these data indicate that the interplay between PARP1 and AMPKα can manipulate mitochondrial turnover, and be targeted to promote longevity.

Kindlin-2 maintains liver homeostasis by regulating GSTP1-OPN-mediated oxidative stress and inflammation in mice.

Hepatocyte plays a principal role in preserving integrity of the liver homeostasis. Our recent study demonstrated that Kindlin-2, a focal adhesion protein that activates integrins and regulates cell-extracellular matrix interactions, plays an important role in regulation of liver homeostasis by inhibiting inflammation pathway; however, the molecular mechanism of how Kindlin-2 KO activates inflammation is unknown. Here, we show that Kindlin-2 loss largely downregulates the antioxidant glutathione-S-transferase P1 in hepatocytes by promoting its ubiquitination and degradation via a mechanism involving protein-protein interaction. This causes overproduction of intracellular reactive oxygen species and excessive oxidative stress in hepatocytes. Kindlin-2 loss upregulates osteopontin in hepatocytes partially because of upregulation of reactive oxygen species and consequently stimulates overproduction of inflammatory cytokines and infiltration in liver. The molecular and histological deteriorations caused by Kindlin-2 deficiency are markedly reversed by systemic administration of an antioxidant N-acetylcysteine in mice. Taken together, Kindlin-2 plays a pivotal role in preserving integrity of liver function.

Loss of phosphatidylinositol-4-phosphate 5-kinase type-1 gamma (Pip5k1c) in mesenchymal stem cells leads to osteopenia by impairing bone remodeling.

Phosphatidylinositol-4-phosphate 5-kinase type-1 gamma (Pip5k1c) is a lipid kinase that plays a pivotal role in the regulation of receptor-mediated calcium signaling in multiple tissues; however, its role in the skeleton is not clear. Here, we show that while deleting Pip5k1c expression in the mesenchymal stem cells using Prx1-Cre transgenic mice does not impair the intramembranous and endochondral ossification during skeletal development, it does cause osteopenia in adult mice, but not rapidly growing young mice. We found Pip5k1c loss dramatically decreases osteoblast formation and osteoid and mineral deposition, leading to reduced bone formation. Furthermore, Pip5k1c loss inhibits osteoblastic, but promotes adipogenic, differentiation of bone marrow stromal cells. Pip5k1c deficiency also impairs cytoplasmic calcium influx and inactivates the calcium/calmodulin-dependent protein kinase, which regulates levels of transcription factor Runx2 by modulating its stability and subsequent osteoblast and bone formation. In addition, Pip5k1c loss reduces levels of the receptor activator of nuclear factor-κB ligand, but not that of osteoprotegerin, its decoy receptor, in osteoblasts in bone and in sera. Finally, we found Pip5k1c loss impairs the ability of bone marrow stromal cells to support osteoclast formation of bone marrow monocytes and reduces the osteoclast precursor population in bone marrow, resulting in reduced osteoclast formation and bone resorption. We conclude Pip5k1c deficiency causes a low-turnover osteopenia in mice, with impairment of bone formation being greater than that of bone resorption. Collectively, we uncover a novel function and mechanism of Pip5k1c in the control of bone mass and identify a potential therapeutic target for osteoporosis.

Knocking down Stard3 decreases adipogenesis with decreased mitochondrial ROS in 3T3-L1 cells.

Start domain-containing protein 3 (Stard3) plays roles in intracellular cholesterol distribution, however, the role of Stard3 in the adipogenesis of 3T3-L1 preadipocytes remains unclear. We demonstrated that Stard3 expression was significantly increased during the adipogenesis of 3T3-L1 preadipocytes, accompanied by an increase of mitochondrial Reactive oxygen species (ROS). Stard3 knocking-down inhibited 3T3-L1 preadipocyte adipogenesis with decreased mitochondrial ROS levels, while ROS inducer rescued the stard3 silencing 3T3 cells with increased ROS. Moreover, Stard3 silencing reduced the expression of peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein (C/EBP)α in 3T3- L1 cells. In conclusion, Stard3 enhanced the adipogenesis of preadipocytes by enhancement of cholesterol redistribution to the mitochondrial, increasing mitochondrial ROS production. These results suggest that Stard3 is an essential factor for the 3T3-L1 cells' differentiation.

Suppression of CD36 attenuates adipogenesis with a reduction of P2X7 expression in 3T3-L1 cells.

Adipogenesis is a process of differentiation from preadipocyte into adipocyte, and is regulated by several transcription factors, including the peroxisome proliferator-activated receptor gamma (PPARγ) and the CCAAT-enhancer-binding protein alpha (C/EBPα). CD36 is a membrane protein which contributes to the metabolic disorders such as obesity. Although the previous study demonstrated CD36 participated in the progression of adipogenesis, the mechanism is still unclear. We report here that knockdown of CD36 expression by CD36 small interfering RNA (siRNA) resulted in a reduction of adipocyte differentiation and adipogenic protein expression. In addition, purinergic receptor P2X, ligand-gated ion channel 7 (P2X7) was downregulated in CD36-knockdown 3T3-L1 cells, suggesting that the suppression of CD36 attenuates adipogenesis via the P2X7 pathway in 3T3-L1 cells.

Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis.

BACKGROUND: Fish oil supplementation has been shown to be associated with a lower risk of metabolic syndrome and benefit a wide range of chronic diseases, such as cardiovascular disease, type 2 diabetes and several types of cancers. However, the evidence of fish oil supplementation on glucose metabolism and insulin sensitivity is still controversial. This meta-analysis summarized the exist evidence of the relationship between fish oil supplementation and insulin sensitivity and aimed to evaluate whether fish oil supplementation could improve insulin sensitivity. METHODS: We searched the Cochrane Library, PubMed, Embase database for the relevant studies update to Dec 2016. Two researchers screened the literature independently by the selection and exclusion criteria. Studies were pooled using random effect models to estimate a pooled SMD and corresponding 95% CI. This meta-analysis was performed by Stata 13.1 software. RESULTS: A total of 17 studies with 672 participants were included in this meta-analysis study after screening from 498 published articles found after the initial search. In a pooled analysis, fish oil supplementation had no effects on insulin sensitivity compared with the placebo (SMD 0.17, 95%CI -0.15 to 0.48, p = 0.292). In subgroup analysis, fish oil supplementation could benefit insulin sensitivity among people who were experiencing at least one symptom of metabolic disorders (SMD 0.53, 95% CI 0.17 to 0.88, p < 0.001). Similarly, there were no significant differences between subgroups of methods of insulin sensitivity, doses of omega-3 polyunsaturated fatty acids (n-3 PUFA) of fish oil supplementation or duration of the intervention. The sensitivity analysis indicated that the results were robust. CONCLUSIONS: Short-term fish oil supplementation is associated with increasing the insulin sensitivity among those people with metabolic disorders.

Pip5k1c expression in osteocytes regulates bone remodeling in mice.

Research background: The role of osteocytes in maintaining bone mass has been progressively emphasized. Pip5k1c is the most critical isoform among PIP5KIs, which can regulate cytoskeleton, biomembrane, and Ca2+ release of cells and participate in many processes, such as cell adhesion, differentiation, and apoptosis. However, its expression and function in osteocytes are still unclear. Materials and methods: To determine the function of Pip5k1c in osteocytes, the expression of Pip5k1c in osteocytes was deleted by breeding the 10-kb mouse Dmp1-Cre transgenic mice with the Pip5k1cfl/fl mice. Bone histomorphometry, micro-computerized tomography analysis, immunofluorescence staining and western blotting were used to determine the effects of Pip5k1c loss on bone mass. In vitro, we explored the mechanism by siRNA knockdown of Pip5k1c in MLO-Y4 cells. Results: Pip5k1c expression was decreased in osteocytes in senescent and osteoporotic tissues both in humans and mice. Loss of Pip5k1c in osteocytes led to a low bone mass in long bones and spines and impaired biomechanical properties in femur, without changes in calvariae. The loss of Pip5k1c resulted in the reduction of the protein level of type 1 collagen in tibiae and MLO-Y4 cells. Osteocyte Pip5k1c loss reduced the osteoblast and bone formation rate with high expression of sclerostin, impacting the osteoclast activities at the same time. Moreover, Pip5k1c loss in osteocytes reduced expression of focal adhesion proteins and promoted apoptosis. Conclusion: Our studies demonstrate the critical role and mechanism of Pip5k1c in osteocytes in regulating bone remodeling. The translational potential of this article: Osteocyte has been considered to a key role in regulating bone homeostasis. The present study has demonstrated that the significance of Pip5k1c in bone homeostasis by regulating the expression of collagen, sclerostin and focal adhesion expression, which provided a possible therapeutic target against human metabolic bone disease.

Relationship Between Control of Cardiovascular Risk Factors and Chronic Kidney Disease Progression, Cardiovascular Disease Events, and Mortality in Chinese Adults.

BACKGROUND: Patients with chronic kidney disease (CKD) are at an elevated risk of cardiovascular disease (CVD) and premature mortality compared to the general population. OBJECTIVES: This study aimed to investigate whether the excess risk of CVD events and death among patients with CKD could be reduced or eliminated through strict control of blood pressure (systolic blood pressure: <130 mm Hg), lipids (low-density lipoprotein cholesterol: <2.6 mmol/L), and glucose (fasting blood glucose: <6.1 mmol/L). METHODS: The authors included 20,254 patients with CKD who were free of CVD or end-stage renal disease and matched them with 35,236 control individuals based on age (±2 years) and sex from the Kailuan study. RESULTS: During a median follow-up period of 12.2 to 12.8 years, 3,875 deaths, 1,888 cases of stroke, 513 cases of myocardial infarction, and 4,825 cases of CKD progression were documented. Among patients with CKD, risk factor controls showed an association with a reduction in myocardial infarction, stroke, CKD progression, and all-cause mortality risk in a dose-dependent manner. Moreover, compared to the non-CKD control individuals, having all 3 risk factors within the target ranges could theoretically eliminate the excess risk of CVD and mortality associated with CKD. Among patients with CKD who had all 3 risk factors controlled, the HRs were 0.80 (95% CI: 0.56-1.14) for myocardial infarction, 0.93 (95% CI: 0.78-1.12) for stroke, and 1.10 (95% CI: 0.98-1.24) for all-cause mortality compared to the non-CKD control individuals. CONCLUSIONS: Patients with CKD who had controlled blood pressure, lipids, and glucose showed no excess risk of death, myocardial infarction, or stroke compared to the general population.

Association between different stages of cardiovascular-kidney-metabolic syndrome and the risk of all-cause mortality.

BACKGROUND AND AIMS: Poor cardiovascular-kidney-metabolic (CKM) health is a major determinant of all-cause mortality, which poses a significant burden on global public health systems and socio-economics. However, the association between different stages of CKM syndrome and the risk of all-cause mortality remains unclear. This study aimed to evaluate the association between different stages of CKM syndrome and risk of all-cause mortality. METHODS: A total of 97,777 adults from the Kailuan Study were included. Cox proportional hazards regression models were applied to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) of all-cause mortality according to different stages of CKM syndrome. RESULTS: Over a median follow-up of 15.0 (14.7-15.2) years, we identified 14,805 all-cause mortality cases. The stage of CKM syndrome was positively associated with the risk of all-cause mortality (p-trend <0.001). Compared with Stage 0, the multivariable-adjusted HRs (95 % CIs) of all-cause mortality were 1.24 (1.06-1.45) for Stage 1, 1.72 (1.48-2.00) for Stage 2, 2.58 (2.22-3.01) for Stage 3 and 3.73 (3.19-4.37) for Stage 4. Moreover, the observed associations were more pronounced in younger adults (aged <60 years) compared with older adults (p for interaction <0.001). CONCLUSIONS: Our data showed that a higher stage of CKM syndrome was associated with a higher risk of all-cause mortality, with a particularly pronounced association observed in younger adults. The study emphasized the need for targeted public health strategies and clinical management tailored to the stages of CKM syndrome, aiming to alleviate its burden on individuals and healthcare systems.

Associations of uric acid with the risk of cardiovascular disease and all-cause mortality among individuals with chronic kidney disease: the Kailuan Study.

AIMS: The relationship between uric acid (UA) concentrations and the risk of cardiovascular disease (CVD), especially for subtypes of CVD among individuals with chronic kidney disease (CKD) is not well understood. This study aimed to investigate whether uric acid concentration was associated with subtypes of CVD and all-cause mortality among individuals with CKD. METHODS: A total of 27,707 individuals with CKD, free of CVD at recruitment from the Kailuan Study, were included. Cox proportional hazards regression models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Over a median follow-up of 11-12 years, we documented 674 myocardial infarctions, 1197 heart failures, 2406 strokes, and 5676 total deaths. Among participants with CKD, compared with those in the lowest tertile of UA, the HRs (95% CIs) of participants in the highest UA tertile were 1.38 (1.13-1.67) for myocardial infarction, 1.60 (1.38-1.85) for heart failure, 1.01 (0.91-1.12) for stroke, and 1.29 (1.21-1.38) for all-cause mortality. Subgroup analyses showed that the associations between UA and heart failure and all-cause mortality were stronger in individuals with eGFR <45 mL/min/1.73m2 compared to their counterparts (Pinteraction<0.05). Additionally, the association between UA and all-cause mortality was stronger among individuals without diabetes than those with diabetes (Pinteraction<0.05). CONCLUSIONS: In individuals with CKD, a higher concentration of UA was associated with a higher risk of myocardial infarction, heart failure, and all-cause mortality, following a dose-response relationship. Our data underscore the importance of UA screening among individuals with CKD for CVD and premature death prevention.

This study investigated the relationship between uric acid (UA) concentrations and the risk of cardiovascular disease and all-cause mortality in individuals with chronic kidney disease (CKD) using the Kailuan Study. A higher concentration of UA was associated with a higher risk of myocardial infarction, heart failure, and all-cause mortality among individuals with CKD, following a dose-response manner.The associations between concentrations of UA and the risk of heart failure and all-cause mortality were more pronounced in individuals with severe kidney impairment (estimated glomerular filtration rate <45 mL/min/1.73m2). Furthermore, the association between UA and all-cause mortality was stronger among individuals without diabetes compared to those with the condition.

Myostatin regulates energy homeostasis through autocrine- and paracrine-mediated microenvironment communication.

Myostatin (MSTN) has long been recognized as a critical regulator of muscle mass. Recently, there has been increasing interest in its role in metabolism. In our study, we specifically knocked out MSTN in brown adipose tissue (BAT) from mice (MSTNΔUCP1) and found that the mice gained more weight than did controls when fed a high-fat diet, with progressive hepatosteatosis and impaired skeletal muscle activity. RNA-Seq analysis indicated signatures of mitochondrial dysfunction and inflammation in the MSTN-ablated BAT. Further studies demonstrated that Kruppel-like factor 4 (KLF4) was responsible for the metabolic phenotypes observed, whereas fibroblast growth factor 21 (FGF21) contributed to the microenvironment communication between adipocytes and macrophages induced by the loss of MSTN. Moreover, the MSTN/SMAD2/3-p38 signaling pathway mediated the expression of KLF4 and FGF21 in adipocytes. In summary, our findings suggest that brown adipocyte-derived MSTN regulated BAT thermogenesis via autocrine and paracrine effects on adipocytes or macrophages, ultimately regulating systemic energy homeostasis.

Targeting Kindlin-2 in adipocytes increases bone mass through inhibiting FAS/PPARγ/FABP4 signaling in mice.

Osteoporosis (OP) is a systemic skeletal disease that primarily affects the elderly population, which greatly increases the risk of fractures. Here we report that Kindlin-2 expression in adipose tissue increases during aging and high-fat diet fed and is accompanied by decreased bone mass. Kindlin-2 specific deletion (K2KO) controlled by Adipoq-Cre mice or adipose tissue-targeting AAV (AAV-Rec2-CasRx-sgK2) significantly increases bone mass. Mechanistically, Kindlin-2 promotes peroxisome proliferator-activated receptor gamma (PPARγ) activation and downstream fatty acid binding protein 4 (FABP4) expression through stabilizing fatty acid synthase (FAS), and increased FABP4 inhibits insulin expression and decreases bone mass. Kindlin-2 inhibition results in accelerated FAS degradation, decreased PPARγ activation and FABP4 expression, and therefore increased insulin expression and bone mass. Interestingly, we find that FABP4 is increased while insulin is decreased in serum of OP patients. Increased FABP4 expression through PPARγ activation by rosiglitazone reverses the high bone mass phenotype of K2KO mice. Inhibition of FAS by C75 phenocopies the high bone mass phenotype of K2KO mice. Collectively, our study establishes a novel Kindlin-2/FAS/PPARγ/FABP4/insulin axis in adipose tissue modulating bone mass and strongly indicates that FAS and Kindlin-2 are new potential targets and C75 or AAV-Rec2-CasRx-sgK2 treatment are potential strategies for OP treatment.

Metabolic crosstalk between skeletal muscle cells and liver through IRF4-FSTL1 in nonalcoholic steatohepatitis.

Inter-organ crosstalk has gained increasing attention in recent times; however, the underlying mechanisms remain unclear. In this study, we elucidate an endocrine pathway that is regulated by skeletal muscle interferon regulatory factor (IRF) 4, which manipulates liver pathology. Skeletal muscle specific IRF4 knockout (F4MKO) mice exhibited ameliorated hepatic steatosis, inflammation, and fibrosis, without changes in body weight, when put on a nonalcoholic steatohepatitis (NASH) diet. Proteomics analysis results suggested that follistatin-like protein 1 (FSTL1) may constitute a link between muscles and the liver. Dual luciferase assays showed that IRF4 can transcriptionally regulate FSTL1. Further, inducing FSTL1 expression in the muscles of F4MKO mice is sufficient to restore liver pathology. In addition, co-culture experiments confirmed that FSTL1 plays a distinct role in various liver cell types via different receptors. Finally, we observed that the serum FSTL1 level is positively correlated with NASH progression in humans. These data indicate a signaling pathway involving IRF4-FSTL1-DIP2A/CD14, that links skeletal muscle cells to the liver in the pathogenesis of NASH.

Kindlin-2 inhibits TNF/NF-κB-Caspase 8 pathway in hepatocytes to maintain liver development and function.

Inflammatory liver diseases are a major cause of morbidity and mortality worldwide; however, underlying mechanisms are incompletely understood. Here we show that deleting the focal adhesion protein Kindlin-2 expression in hepatocytes using the Alb-Cre transgenic mice causes a severe inflammation, resulting in premature death. Kindlin-2 loss accelerates hepatocyte apoptosis with subsequent compensatory cell proliferation and accumulation of the collagenous extracellular matrix, leading to massive liver fibrosis and dysfunction. Mechanistically, Kindlin-2 loss abnormally activates the tumor necrosis factor (TNF) pathway. Blocking activation of the TNF signaling pathway by deleting TNF receptor or deletion of Caspase 8 expression in hepatocytes essentially restores liver function and prevents premature death caused by Kindlin-2 loss. Finally, of translational significance, adeno-associated virus mediated overexpression of Kindlin-2 in hepatocytes attenuates the D-galactosamine and lipopolysaccharide-induced liver injury and death in mice. Collectively, we establish that Kindlin-2 acts as a novel intrinsic inhibitor of the TNF pathway to maintain liver homeostasis and may define a useful therapeutic target for liver diseases.

Transcriptomics Dissection of Calorie Restriction and Exercise Training in Brown Adipose Tissue and Skeletal Muscle.

Calorie restriction (CR) and exercise training (EX) are two critical lifestyle interventions for the prevention and treatment of metabolic diseases, such as obesity and diabetes. Brown adipose tissue (BAT) and skeletal muscle are two important organs for the generation of heat. Here, we undertook detailed transcriptional profiling of these two thermogenic tissues from mice treated subjected to CR and/or EX. We found transcriptional reprogramming of BAT and skeletal muscle as a result of CR but little from EX. Consistent with this, CR induced alterations in the expression of genes encoding adipokines and myokines in BAT and skeletal muscle, respectively. Deconvolution analysis showed differences in the subpopulations of myogenic cells, mesothelial cells and endogenic cells in BAT and in the subpopulations of satellite cells, immune cells and endothelial cells in skeletal muscle as a result of CR or EX. NicheNet analysis, exploring potential inter-organ communication, indicated that BAT and skeletal muscle could mutually regulate their fatty acid metabolism and thermogenesis through ligands and receptors. These data comprise an extensive resource for the study of thermogenic tissue molecular responses to CR and/or EX in a healthy state.

Skeletal muscle-specific DJ-1 ablation-induced atrogenes expression and mitochondrial dysfunction contributing to muscular atrophy.

BACKGROUND: DJ-1 is a causative gene for Parkinson's disease. DJ-1-deficient mice develop gait-associated progressive behavioural abnormalities and hypoactive forearm grip strength. However, underlying activity mechanisms are not fully explored. METHODS: Western blotting and quantitative real-time polymerase chain reaction approaches were adopted to analyse DJ-1 expression in skeletal muscle from aged humans or mice and compared with young subjects. Skeletal muscle-specific-DJ-1 knockout (MDKO) mice were generated, followed by an assessment of the physical activity phenotypes (grip strength, maximal load capacity, and hanging, rotarod, and exercise capacity tests) of the MDKO and control mice on the chow diet. Muscular atrophy phenotypes (cross-sectional area and fibre types) were determined by imaging and quantitative real-time polymerase chain reaction. Mitochondrial function and skeletal muscle morphology were evaluated by oxygen consumption rate and electron microscopy, respectively. Tail suspension was applied to address disuse atrophy. RNA-seq analysis was performed to indicate molecular changes in muscles with DJ-1 ablation. Dual-luciferase reporter assays were employed to identify the promoter region of Trim63 and Fbxo32 genes, which were indirectly regulated by DJ-1 via the FoxO1 pathway. Cytoplasmic and nuclear fractions of DJ-1-deleted muscle cells were analysed by western blotting. Compound 23 was administered into the gastrocnemius muscle to mimic the of DJ-1 deletion effects. RESULTS: DJ-1 expression decreased in atrophied muscles of aged human (young men, n = 2; old with aged men, n = 2; young women, n = 2; old with aged women, n = 2) and immobilization mice (n = 6, P < 0.01). MDKO mice exhibited no body weight difference compared with control mice on the chow diet (Flox, n = 8; MDKO, n = 9). DJ-1-deficient muscles were slightly dystrophic (Flox, n = 7; MDKO, n = 8; P < 0.05), with impaired physical activities and oxidative capacity (n = 8, P < 0.01). In disuse-atrophic conditions, MDKO mice showed smaller cross-sectional area (n = 5, P < 0.01) and more central nuclei than control mice (Flox, n = 7; MDKO, n = 6; P < 0.05), without alteration in muscle fibre types (Flox, n = 6; MDKO, n = 7). Biochemical analysis indicated that reduced mitochondrial function and upregulated of atrogenes induced these changes. Furthermore, RNA-seq analysis revealed enhanced activity of the FoxO1 signalling pathway in DJ-1-ablated muscles, which was responsible for the induction of atrogenes. Finally, compound 23 (an inhibitor of DJ-1) could mimic the effects of DJ-1 ablation in vivo. CONCLUSIONS: Our results illuminate the crucial of skeletal muscle DJ-1 in the regulation of catabolic signals from mechanical stimulation, providing a therapeutic target for muscle wasting diseases.

Treatment with ginger ameliorates fructose-induced Fatty liver and hypertriglyceridemia in rats: modulation of the hepatic carbohydrate response element-binding protein-mediated pathway.

Ginger has been demonstrated to improve lipid derangements. However, its underlying triglyceride-lowering mechanisms remain unclear. Fructose overconsumption is associated with increase in hepatic de novo lipogenesis, thereby resulting in lipid derangements. Here we found that coadministration of the alcoholic extract of ginger (50 mg/kg/day, oral gavage, once daily) over 5 weeks reversed liquid fructose-induced increase in plasma triglyceride and glucose concentrations and hepatic triglyceride content in rats. Plasma nonesterified fatty acid concentration was also decreased. Attenuation of the increased vacuolization and Oil Red O staining area was evident on histological examination of liver in ginger-treated rats. However, ginger treatment did not affect chow intake and body weight. Further, ginger treatment suppressed fructose-stimulated overexpression of carbohydrate response element-binding protein (ChREBP) at the mRNA and protein levels in the liver. Consequently, hepatic expression of the ChREBP-targeted lipogenic genes responsible for fatty acid biosynthesis was also downregulated. In contrast, expression of neither peroxisome proliferator-activated receptor- (PPAR-) alpha and its downstream genes, nor PPAR-gamma and sterol regulatory element-binding protein 1c was altered. Thus the present findings suggest that in rats, amelioration of fructose-induced fatty liver and hypertriglyceridemia by ginger treatment involves modulation of the hepatic ChREBP-mediated pathway.

Osteocyte ß1 integrin loss causes low bone mass and impairs bone mechanotransduction in mice.

Background: The key focal adhesion protein ß1 integrin plays an essential role in early skeletal development. However, roles of ß1 integrin expression in osteocytes during the regulation of bone homeostasis and mechanotransduction are incompletely understood. Materials and methods: To study the in vivo function of osteocyte ß1 integrin in bone, we utilized the 10-kb Dmp1 (Dentin matrix acidic phosphoprotein 1)-Cre to generate mice with ß1 integrin deletion in this cell type. Micro-computerized tomography, bone histomorphometry and immunohistochemistry were performed to determine the effects of osteocyte ß1 integrin loss on bone mass accrual and biomechanical properties. In vivo tibial loading model was applied to study the possible involvement of osteocyte ß1 integrin in bone mechanotransduction. Results: Loss of ß1 integrin expression in osteocytes resulted in a severe low bone mass and impaired biomechanical properties in load-bearing long bones and spines, but not in non-weight-bearing calvariae, in mice. The loss of ß1 integrin led to enlarged size of lacunar-canalicular system, abnormal cell morphology, and disorientated nuclei in osteocytes. Furthermore, ß1 integrin loss caused shortening and disorientated collagen I fibers in long bones. Osteocyte ß1 integrin loss did not impact the osteoclast activities, but significantly reduced the osteoblast bone formation rate and, in the meantime, enhanced the adipogenic differentiation of the bone marrow stromal cells in the bone microenvironment. In addition, tibial loading failed to accelerate the anabolic bone formation and improve collagen I fiber integrity in mutant mice. Conclusions: Our studies demonstrate an essential role of osteocyte ß1 integrin in regulating bone homeostasis and mechanotransduction. The transnational potential of this article : This study reveals the regulatory roles of osteocyte ß1 integrin in vivo for the maintenance of bone mass accrual, biomechanical properties, extracellular matrix integrity as well as bone mechanobiology, which defines ß1 integrin a potential therapeutic target for skeletal diseases, such as osteoporosis.

Kindlin-2 haploinsufficiency protects against fatty liver by targeting Foxo1 in mice.

Nonalcoholic fatty liver disease (NAFLD) affects a large population with incompletely defined mechanism(s). Here we report that Kindlin-2 is dramatically up-regulated in livers in obese mice and patients with NAFLD. Kindlin-2 haploinsufficiency in hepatocytes ameliorates high-fat diet (HFD)-induced NAFLD and glucose intolerance without affecting energy metabolism in mice. In contrast, Kindlin-2 overexpression in liver exacerbates NAFLD and promotes lipid metabolism disorder and inflammation in hepatocytes. A C-terminal region (aa 570-680) of Kindlin-2 binds to and stabilizes Foxo1 by inhibiting its ubiquitination and degradation through the Skp2 E3 ligase. Kindlin-2 deficiency increases Foxo1 phosphorylation at Ser256, which favors its ubiquitination by Skp2. Thus, Kindllin-2 loss down-regulates Foxo1 protein in hepatocytes. Foxo1 overexpression in liver abrogates the ameliorating effect of Kindlin-2 haploinsufficiency on NAFLD in mice. Finally, AAV8-mediated shRNA knockdown of Kindlin-2 in liver alleviates NAFLD in obese mice. Collectively, we demonstrate that Kindlin-2 insufficiency protects against fatty liver by promoting Foxo1 degradation.