Decreased Expression Of PPARγ Research Articles

Effects of inorganic phosphate on stem cells isolated from human exfoliated deciduous teeth

Calcium phosphate-based materials (CaP) are introduced as potential dental pulp capping materials for deciduous teeth. The present study investigated the influence of inorganic phosphate (Pi) on regulating stem cells isolated from human exfoliated deciduous teeth (SHED). SHEDs were treated with Pi. Cell cycle progression and apoptosis were examined using flow cytometry analysis. Osteo/odontogenic and adipogenic differentiation were analyzed using alizarin red S and oil red O staining, respectively. The mRNA expression profile was investigated using a high-throughput RNA sequencing technique. Pi increased the late apoptotic cell population while cell cycle progression was not altered. Pi upregulated osteo/odontoblastic gene expression and enhanced calcium deposition. Pi-induced mineralization was reversed by pretreatment of cells with Foscarnet, or p38 inhibitor. Pi treatment inhibited adipogenic differentiation as determined by decreased PPARγ expression and reduced intracellular lipid accumulation. Bioinformatic analysis of gene expression profiles demonstrated several involved pathways, including PI3K/AKT, MAPK, EGFR, and VEGF signaling. In conclusion, Pi enhanced osteo/odontogenic but inhibited adipogenic differentiation in SHED.

Impinging Flow Mediates Vascular Endothelial Cell Injury through the PKCα/ERK/PPARγ Pathway in vitro

Introduction: This study aimed to elucidate the mechanisms underlying endothelial injury in the context of intracranial aneurysm formation and development, which are associated with vascular endothelial injury caused by hemodynamic abnormalities. Specifically, we focus on the involvement of PKCα, an intracellular signaling transmitter closely linked to vascular diseases, and its role in activating MAPK. Additionally, we investigate the protective effects of PPARγ, a vasculoprotective factor known to attenuate vascular injury by mitigating the inflammatory response in the vessel wall. Methods: The study employs a modified T-chamber to replicate fluid flow conditions at the artery bifurcation, allowing us to assess wall shear stress effects on human umbilical vein endothelial cells in vitro. Through experimental manipulations involving PKCα knockdown and Ca2+ and MAPK inhibitors, we evaluated the phosphorylation status of PKCα, NF-κB, ERK5, ERK1/2, JNK1/2/3, and P38, as well as the expression levels of PPARγ, NF-κB, and MMP2 via Western blot analysis. The cellular localization of phosphorylated NF-κB was determined using immunofluorescence. Results: Our results showed that impinging flow resulted in the activation of PKCα, followed by the phosphorylation of ERK5, ERK1/2, and JNK1/2/3, leading to a decrease in PPARγ expression, an increase in the expression of NF-κB and MMP2, and the induction of apoptotic injury. Inhibition of PKCα activation or knockdown of PKCα using shRNA leads to a suppression of ERK5, ERK1/2, JNK1/2/3, and P38 phosphorylation, an elevation in PPARγ expression, and a reduction in NF-κB and MMP2 expression, alleviated apoptotic injury. Furthermore, we observe that the regulation of PPARγ, NF-κB, and MMP2 expression is influenced by ERK5 and ERK1/2 phosphorylation, and activation of PPARγ effectively counteracts the elevated expression of NF-κB and MMP2. Conclusion: Our findings suggest that the PKCα/ERK/PPARγ pathway plays a crucial role in mediating endothelial injury under conditions of impinging flow, with potential implications for vascular diseases and intracranial aneurysm development.

Suppressed Akt/GSK-3β/β-catenin signaling contributes to excessive adipogenesis of fibro-adipogenic progenitors after rotator cuff tears.

Muscular fatty infiltration is a common and troublesome pathology after rotator cuff tears (RCT), which mainly derives from fibro-adipogenic progenitors (FAPs). Compared to the RCT, fatty infiltration is not so severe in Achilles tendon tears (ATT). The knowledge of why fatty infiltration is more likely to occur after RCT is limited. In this study, more severe fatty infiltration was verified in supraspinatus than gastrocnemius muscles after tendon injury. Additionally, we revealed higher adipogenic differentiation ability of RCT-FAPs in vitro. Activation of Akt significantly stimulated GSK-3β/β-catenin signaling and thus decreased PPARγ expression and adipogenesis of RCT-FAPs, while the inhibition effect was attenuated by β-catenin inhibitor. Furthermore, Wnt signaling activator BML-284 limited adipogenesis of RCT-FAPs, alleviated muscular fatty infiltration, and improved parameters in gait analysis and treadmill test for RCT model. In conclusion, our study demonstrated that suppressed Akt/GSK-3β/β-catenin signaling increased PPARγ expression and thus contributed to excessive adipogenesis in RCT-FAPs. Modulation of Akt/GSK-3β/β-catenin signaling ameliorated excessive fatty infiltration of rotator cuff muscles and improved shoulder function after RCT.

Mechanical stress induced EndoMT in endothelial cells through PPARγ downregulation

Portal hypertension is a group of clinical syndromes induced by increased portal system pressure due to various etiologies including cirrhosis. When portal hypertension develops, the portal vein dilates and endothelial cells (ECs) in the portal vein are subjected to mechanical stretch. In this study, elastic silicone chambers were used to simulate the effects of mechanical stretch on ECs under portal hypertension. We found that mechanical stretch decreased PPARγ expression in ECs by blocking the PI3K/AKT/CREB signaling pathway or increasing NEDD4-mediated ubiquitination and degradation of PPARγ. Moreover, PPARγ downregulation triggered Endothelial-to-mesenchymal transition (EndoMT) in ECs under stretch by promoting Smad3 phosphorylation. The PPARγ agonist rosiglitazone mitigated stretch-induced EndoMT in vitro and alleviated EndoMT of the portal vein endothelium in cirrhotic rats.

Caloric restriction increases the resistance of aged heart to myocardial ischemia/reperfusion injury via modulating AMPK–SIRT1–PGC1a energy metabolism pathway

A large number of data suggest that caloric restriction (CR) has a protective effect on myocardial ischemia/reperfusion injury (I/R) in the elderly. However, the mechanism is still unclear. In this study, we created the I/R model in vivo by ligating the mice left coronary artery for 45 min followed by reperfusion. C57BL/6J wild-type mice were randomly divided into a young group fed ad libitum (y-AL), aged fed ad libitum (a-AL) and aged calorie restriction group (a-CR, 70% diet restriction), and fed for 6 weeks. The area of myocardial infarction was measured by Evan’s blue-TTC staining, plasma cholesterol content quantified by ELISA, fatty acids and glucose measured by Langendorff working system, as well as protein expression of AMPK/SIRT1/PGC1a signaling pathway related factors in myocardial tissue detected by immunoblotting. Our results showed that CR significantly reduced infarct size in elderly mice after I/R injury, promoted glycolysis regardless of I/R injury, and restored myocardial glucose uptake in elderly mice. Compared with a-AL group, CR significantly promoted the expression of p-AMPK, SIRT1, p-PGC1a, and SOD2, but decreased PPARγ expression in aged mice. In conclusion, our results suggest that CR protects elderly mice from I/R injury by altering myocardial substrate energy metabolism via the AMPK/SIRT1/PGC1a pathway.

Lycopene Modulates Oxidative Stress and Inflammation in Hypercholesterolemic Rats

The complicated disorder of hypercholesterolemia has several underlying factors, including genetic and lifestyle factors. Low LDL cholesterol and elevated serum total cholesterol are its defining features. A carotenoid with antioxidant quality is lycopene. Examining lycopene activity in an animal model of hypercholesterolemia induced using food was the aim of this investigation. Triglycerides, LDL cholesterol, HDL cholesterol, and plasma total cholesterol were all measured. Biomarkers of renal and cardiac function were also examined. Apoptotic indicators, pro-inflammatory markers, and oxidative stress were also assessed. Additionally, the mRNA expression of paraoxonase 1 (PON-1), peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-γ coactivator 1 alpha (PGC-1α) in cardiac and renal tissues was examined. Rats showed elevated serum lipid levels, renal and cardiac dysfunction, significant oxidative stress, and pro-inflammatory and apoptotic markers at the end of the study. Treatment with lycopene significantly corrected and restored these changes. Additionally, lycopene markedly increased the mRNA expression of PGC-1α and PON-1, and decreased PPAR-γ expression. It was determined that lycopene has the capacity to modulate the PPAR-γ and PON-1 signaling pathway in order to preserve the cellular energy metabolism of the heart and kidney, which in turn reduces tissue inflammatory response and apoptosis. According to these findings, lycopene may be utilized as a medication to treat hypercholesterolemia. However, further studies should be conducted first to determine the appropriate dose and any adverse effects that may appear after lycopene usage in humans.

Angelica sinensis polysaccharides prevents hematopoietic regression in D-Galactose-Induced aging model via attenuation of oxidative stress in hematopoietic microenvironment.

Extrinsic molecular mechanisms that regulate hematopoietic stem/progenitor cell (HSPC) aging are still poorly understood, and a potential protective medication needs to be explored. The senescent parameters of hematopoietic cells and bone marrow stromal cells (BMSCs) including cell cycle analysis, senescence-associated SA-β-gal staining and signals, hematopoietic factors and cellular junction were analyzed in femur and tibia of rats. Furthermore, Sca-1+ HSPCs and BMSCs co-culture system was established to evaluate the direct effects of BMSC feeder layer to HSPCs. Oxidative DNA damage indicators in Sca-1+ HSCs and senescence-associated secretory phenotype (SASP) of BMSCs, gap junction intercellular communication between BMSCs, osteogenesis/adipogenisis differentiation balance of BMSCs were detected. In the D-gal pre-administrated rats, ASP treatment rescued senescence of hematopoietic cells and BMSCs, reserved CFU-GEMM; also, ASP treatment attenuated stromal oxidative load, ameliorated SCF, CXCL12, and GM-CSF production, increased Connexin-43 (Cx43) expression. BMSCs and Sca-1+ HSPCs co-cultivation demonstrated that ASP treatment prevented oxidative DNA damage response in co-cultured Sca-1+ HSPCs induced by D-gal pre-administration of feeder layer and the underlying mechanism may be related to ASP ameliorating feeder layer dysfunction due to D-gal induced senescence via inhibiting secretion of IL-1, IL-6, TNF-α, and RANTES, enhancing Cx43-mediated intercellular communication, improving Runx2 expression whereas decreasing PPARγ expression in BMSCs. The antioxidant property of ASP may provide a stroma-mediated potential therapeutic strategy for HSPC aging.

Investigation of obesogenic effects of hexachlorobenzene, DDT and DDE in male rats

Obesity has become a very important public health problem and is increasing globally. Genetics, individual and environmental factors play roles in the etiology of this complex disorder. Recently, several environmental pollutants have been suggested to have obesogenic activities. Peroxisome proliferator activating receptor gamma (PPARγ), uncoupling protein-1 (UCP1) and their expression in white adipose tissue (WAT) and brown adipose tissue (BAT) play key roles in adipogenesis. UCP3 and irisin were reported to play roles in non-shivering thermogenesis. Our primary aim was to investigate obesogenic effects of hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in rats. In addition, thermoregulatory effects of HCB, DDT and DDE were also investigated by analyzing the levels of Ucp3 and irisin. Thirty-two adult male Sprague-Dawley rats were randomly divided into four groups as control, HCB, DDT and DDE. Animals were administered with organochlorine pesticides (OCPs; 5 mg/kg bw) by oral gavage every other day for five weeks. At the end of the experimental period, the animals were sacrificed, BAT and WAT samples were collected to analyze Pparγ, Ucp1 and Ucp3 levels. Moreover, skeletal muscle samples were collected to examine Ucp3 and irisin levels. Serum glucose, cholesterol and triglyceride levels were also determined. Body weight and core temperature of the animals were not significantly affected by any of the OCP administration. Serum glucose, cholesterol and triglyceride levels were similar among the experimental groups. Pparγ expression was significantly elevated by HCB administration only in WAT (p < 0.05). On the other hand, both Pparγ and Ucp1 expressions were diminished in WAT and BAT (p < 0.01) by DDT treatment, while in WAT, DDE significantly decreased Pparγ expression without altering its expression in BAT (p < 0.001). Ucp3 and irisin levels in skeletal muscle were not altered. Our findings show that both DDT and DDE reduce the browning of WAT by suppressing white adipocytes and thus may have obesogenic activity in male rats without altering thermoregulation. In addition, HCB, DDT and DDE-induced alterations in expression of Pparγ and Ucp1 in WAT implicates differential regulation of adipogenic processes.

Arsenite inhibits M2a polarization of macrophages through downregulation of peroxisome proliferator-activated receptor gamma

Arsenite (As+3) is a group one human carcinogen, which has been associated with many diseases. Previous studies indicated that As+3 could inhibit wound healing and repair. M2a cells are known as tissue remodeling macrophages, which play an important role in wound repair process. Peroxisome proliferator-activated receptor gamma (PPAR-γ), a key regulator of lipid and glucose metabolism, was found to mediate the IL-4-dependent M2a polarization of macrophages. In the present study, As+3 induced dose-dependent inhibition of M2a polarization starting from 0.1 μM in THP-1-derived macrophages stimulated with 20 ng/mL IL-4. Increased lipid accumulation and decreased PPAR-γ expression were also observed in As+3-treated M2a macrophages. Rosiglitazone (RSG), a potent PPAR-γ agonist, alleviated the suppressions of PPAR-γ and M2a polarization induced by 2 μM As+3. Collectively, these results not only demonstrated that As+3 was able to inhibit polarization of M2a cells through PPAR-γ suppression, but also indicated that PPAR-γ could be utilized as a target for the prevention and treatment of As+3-induced immunotoxicity.

Functional characterization of a novel p.Ser76Thr variant in IGFBP4 that associates with body mass index in American Indians.

Insulin-like growth factor binding protein 4 (IGFBP4) is involved in adipogenesis, and IGFBP4 null mice have decreased body fat through decreased PPAR-γ expression. In the current study, we assessed whether variation in the IGFBP4 coding region influences body mass index (BMI) in American Indians who are disproportionately affected by obesity. Whole exome sequence data from a population-based sample of 6779 American Indians with longitudinal measures of BMI were used to identify variation in IGFBP4 that associated with BMI. A novel variant that predicts a p.Ser76Thr in IGFBP4 (Thr-allele frequency = 0.02) was identified which associated with the maximum BMI measured during adulthood (BMI 39.8 kg/m2 for Thr-allele homozygotes combined with heterozygotes vs. 36.2 kg/m2 for Ser-allele homozygotes, β = 6.7% per Thr-allele, p = 8.0 × 10-5, adjusted for age, sex, birth-year and the first five genetic principal components) and the maximum age- and sex-adjusted BMI z-score measured during childhood/adolescence (z-score 0.70 SD for Thr-allele heterozygotes vs. 0.32 SD for Ser-allele homozygotes, β = 0.37 SD per Thr-allele, p = 8.8 × 10-6). In vitro functional studies showed that IGFBP4 with the Thr-allele (BMI-increasing) had a 55% decrease (p = 0.0007) in FOXO-induced transcriptional activity, reflecting increased activation of the PI3K/AKT pathway mediated through increased IGF signaling. Over-expression and knock-down of IGFBP4 in OP9 cells during differentiation showed that IGFBP4 upregulates adipogenesis through PPARγ, CEBPα, AGPAT2 and SREBP1 expression. We propose that this American Indian specific variant in IGFBP4 affects obesity via an increase of IGF signaling.

Nano SIM@ZIF-8 modified injectable High-intensity biohydrogel with bidirectional regulation of osteogenesis and Anti-adipogenesis for bone repair

Hyperlipidemia negatively affects osteogenesis, thereby impairing bone healing. However, few biomaterials have been developed for bone tissue engineering to solve this problem. Herein, the preparation of specific biomaterials that can promote osteogenesis and suppress adipogenesis holds great promise for reconstructive bone defect treatment. In this study, we propose the construction of a nano simvastatin-laden zeolitic imidazolate framework-8 (nano SIM@ZIF-8) modified injectable high-intensity biohydrogel, composed of poly (ethylene glycol) diacrylate (PEGDA) and sodium alginate (SA) to form nano SIM@ZIF-8/PEGDA/SA (defined as nSZPS), which can stimulate osteogenic differentiation and inhibit adipogenic differentiation. The characterization and drug loading efficiency of the nanoparticles were examined to confirm the successful synthesis of nano SIM@ZIF-8. Within the PEGDA/SA delivery platform, nSZPS showed excellent injectability and mechanical strength through rheological and mechanical tests. Moreover, owing to the sustained release of SIM and bioactive Zn ions, nSZPS not only possessed excellent biocompatibility but also significantly enhanced the osteogenic differentiation ability and inhibited the adipogenic efficacy of BMSCs in vitro. Furthermore, nSZPS showed excellent osseointegration and lipid-lowering abilities in healing bone defects of hyperlipidemic rats by decreasing PPARγ expression and increasing RUNX2 expression in vivo. In addition, the bidirectional regulatory mechanisms of nSZPS in bone defects may be closely related to the mutual regulation of the PPARγ and Wnt/β-CATENIN pathways. In summary, this nano SIM@ZIF-8 modified injectable high-intensity biohydrogel might be a promising strategy for complex bone regeneration, especially in hyperlipidemic microenvironments.

Allium victorialis L. Extracts Promote Activity of FXR to Ameliorate Alcoholic Liver Disease: Targeting Liver Lipid Deposition and Inflammation

Allium victorialis L. (AVL) is a traditional medicinal plant recorded in the Compendium of Materia Medica (the Ming Dynasty). In general, it is used for hemostasis, analgesia, anti-inflammation, antioxidation, and to especially facilitate hepatoprotective effect. In recent years, it has received more and more attention due to its special nutritional and medicinal value. The present study investigates the effect and potential mechanism of AVL against alcoholic liver disease (ALD). C57BL/6 mice were fed Lieber–DeCarli liquid diet containing 5% ethanol plus a single ethanol gavage (5 g/kg), and followed up with the administration of AVL or silymarin. AML12 cells were stimulated with ethanol and incubated with AVL. AVL significantly reduced serum transaminase and triglycerides in the liver and attenuated histopathological changes caused by ethanol. AVL significantly inhibited SREBP1 and its target genes, regulated lipin 1/2, increased PPARα and its target genes, and decreased PPARγ expression caused by ethanol. In addition, AVL significantly enhanced FXR, LXRs, Sirt1, and AMPK expressions compared with the EtOH group. AVL also inhibited inflammatory factors, NLRP3, and F4/80 and MPO, macrophage and neutrophil markers. In vitro, AVL significantly reduced lipid droplets, lipid metabolism enzymes, and inflammatory factors depending on FXR activation. AVL could ameliorate alcoholic steatohepatitis, lipid deposition and inflammation in ALD by targeting FXR activation.

Dispersion and utilization of lipid droplets mediates respiratory syncytial virus-induced airway hyperresponsiveness.

Respiratory viral infections (RSV) can induce acute asthma attacks, thereby destroying lung function and accelerating the progression of the disease. However, medications in the stable phase of asthma are often not effective for acute attacks induced by viral infections. We aimed to clarify the possible mechanism of viral infection-induced asthma through fatty acid metabolism. The airway resistances, inflammatory injuries, and oxidative stress in the RSV-induced animal models were significantly higher than those in the control group at acute phase (7 days) and chronic phase (28 days). Moreover, the concentrations of the medium- and long-chain fatty acids in lung tissue at (28 days) were significantly increased, including 14:0 (myristic acid), 16:0 (palmitic acid, PA), 18:1 (oleic acid, OA), and 18:2 (linoleic acid, LA) using non-targeted metabonomics. Airway epithelial cells treated with RSV showed the reduced expression of FSP27, RAB8A, and PLIN5, which caused the fusion and growth of lipid droplet (LD), and increased expression of the LD dispersion gene perilipin 2. There was also a decrease in PPARγ expression and an increase in the fatty acid catabolism gene PPARα, causing lipid oxidation, free fatty acid releases, and an upsurge in IL-1, IL-2, IL-4, and IL-6 expression, which could be abrogated by GPR40 inhibitor. Treated mice or epithelial cells with C18 fatty acid exhibited inhibition of epithelial proliferation, increases of inflammation, and oxidative damage. RSV promoted lipid dispersion and utilization, causing enlarged oxidative injuries and an upsurge in the pro-inflammatory cytokines, leading to the progression of airway hyperresponsiveness (AHR).

Insulin signaling establishes a developmental trajectory of adipose regulatory T cells.

Systematic characterizations of adipose regulatory T (Treg) cell subsets and their phenotypes remain uncommon. Using single-cell ATAC-sequencing and paired single-cell RNA and T cell receptor (TCR) sequencing to map mouse adipose Treg cells, we identified CD73hiST2lo and CD73loST2hi subsets with distinct clonal expansion patterns. Analysis of TCR-sharing data implied a state transition between CD73hiST2lo and CD73loST2hi subsets. Mechanistically, we revealed that insulin signaling occurs through a HIF-1α-Med23-PPAR-γ axis to drive the transition of CD73hiST2lo into a CD73loST2hi adipose Treg cell subset. Treg cells deficient in insulin receptor, HIF-1α or Med23 have decreased PPAR-γ expression that in turn promotes accumulation of CD73hiST2lo adipose Treg cells and physiological adenosine production to activate beige fat biogenesis. We therefore unveiled a developmental trajectory of adipose Treg cells and its dependence on insulin signaling. Our findings have implications for understanding the dynamics of adipose Treg cell subsets in aged and obese contexts.

TRIM27-mediated ubiquitination of PPARγ promotes glutamate-induced cell apoptosis and inflammation

Neurotoxicity induced by glutamate (Glu) is often used to study the signaling mechanism of neurological disorders. The identification of specific genetic factors that cause Glu-induced neurotoxicity provides evidence for the common pathways of neuronal apoptosis and inflammation. TRIM27 has been found to induce apoptosis and inflammation. Nevertheless, there is little evidence that TRIM27 is associated with Glu-induced neurotoxicity. We found that TRIM27 expression was increased in epilepsy patients and in HT22 cells following Glu treatment. Glu-mediated cell apoptosis, decreased PPARγ expression, and increased levels of cleaved Caspase-3 and IL-1β expression in HT22 cells were significantly inhibited by TRIM27 knockdown. TRIM27 overexpression significantly induced cell apoptosis and expression of cleaved Caspase-3 and IL-1β, but inhibited PPARγ expression in HT22 cells, which were reversed by ROZ, suggesting the involvement of PPARγ in TRIM27-mediated cell apoptosis and inflammation in HT22 cells. Mechanically, TRIM27 ubiquitinates and degrades PPARγ, following induces cleaved Caspase-3 and IL-1β expression. Clinically, increased expression of TRIM27 in epilepsy patients was associated with decreased PPARγ expression. Taken together, our study suggests that TRIM27-mediated ubiquitination of PPARγ promotes Glu-induced HT22 cell apoptosis and IL-1β release.

Altered PPARγ Expression Promotes Myelin-Induced Foam Cell Formation in Macrophages in Multiple Sclerosis.

Macrophages play a crucial role during the pathogenesis of multiple sclerosis (MS), a neuroinflammatory autoimmune disorder of the central nervous system. Important regulators of the metabolic and inflammatory phenotype of macrophages are liver X receptors (LXRs) and peroxisome proliferator-activated receptors (PPARs). Previously, it has been reported that PPARγ expression is decreased in peripheral blood mononuclear cells of MS patients. The goal of the present study was to determine to what extent PPARγ, as well as the closely related nuclear receptors PPARα and β and LXRα and β, are differentially expressed in monocytes from MS patients and how this change in expression affects the function of monocyte-derived macrophages. We demonstrate that monocytes of relapsing-remitting MS patients display a marked decrease in PPARγ expression, while the expression of PPARα and LXRα/β is not altered. Interestingly, exposure of monocyte-derived macrophages from healthy donors to MS-associated proinflammatory cytokines mimicked this reduction in PPARγ expression. While a reduced PPARγ expression did not affect the inflammatory and phagocytic properties of myelin-loaded macrophages, it did impact myelin processing by increasing the intracellular cholesterol load of myelin-phagocytosing macrophages. Collectively, our findings indicate that an inflammation-induced reduction in PPARγ expression promotes myelin-induced foam cell formation in macrophages in MS.

Regulation of peroxisome proliferator-activated receptor-gamma activity affects the hepatic stellate cell activation and the progression of NASH via TGF-β1/Smad signaling pathway.

Development of liver fibrosis is associated with activation of quiescent hepatic stellate cells (HSCs) into myofibroblasts (activated HSCs), which produce excessive extracellular matrix. Peroxisome proliferator-activated receptor-gamma (PPAR-γ) exerts protective effects on hepatic inflammation and fibrosis. The current study was to explore the function of PPAR-γ on HSC activation and progression of nonalcoholic steatohepatitis (NASH). Our study found that HSCs were gradually activated during the progression of methionine-choline-deficient (MCD) diet-induced NASH, accompanied by decreased PPAR-γ expression and activated TGF-β1/Smad signaling pathway in the liver. PPAR-γ agonist was found to inhibit primary HSCs and NIH/3T3 fibroblast activation and reverted their phenotypical morphology induced by TGF-β1 in vitro. In addition to this, PPAR-γ agonist decreased expression of TGF-β1 and phosphorylation of Smad2/3 while increased expression of Smad7. In vivo, rosiglitazone, a PPAR-γ agonist, inhibited HSC activation and alleviated liver fibrosis and inflammation similarly via inhibiting the activation of TGF-β1/Smad signaling pathway. In parallel, rosiglitazone alleviated hepatic lipid accumulation and peroxidation, beneficial to reverse of NASH. From these findings, it can be concluded that the gradual activation of HSCs is crucial to the progression of NASH and modulating PPAR-γ expression can affect HSC activation via TGF-β1/Smad signaling pathway and thereby influence hepatic fibrogenesis.

CRTC1 Maintains Metabolic Homeostasis and Protects Against Partial Lipodystrophy &amp; Insulin Resistance by Regulating Diet‐Responsive White Adipose Tissue Remodeling

Humans evolved the ability to store lipid in specialized tissue called adipose to support survival. Adipose provides an energy depot that can be quickly mobilized in response to acute stress (fight‐or‐flight), for reproduction and during extended fasting. Defects in white adipose tissue (WAT) function, and inability of the WAT depots to expand in the context of overnutrition, will lead to ectopic lipid accumulation in the muscle and liver triggering serious metabolic diseases such as type 2 diabetes (T2D).Our data demonstrate that CREB Regulated Transcription Coactivator 1 (CRTC1) gene function is important in maintaining metabolic fitness. CRTC1 is expressed primarily in the hypothalamus where it controls satiety in response to cAMP and Ca2+ signals. Recent studies identified small nucleotide polymorphisms (SNPs) in the human gene locus CRTC1 that correlate with decreased adiposity in the context of obesity, indicating that CRTC1 may play an important role in adipose function. Here, we describe a previously unknown role of CRTC1 in the regulation of epididymal WAT (eWAT) expansion in response to high fat diet (HFD).Basal CRTC1 protein expression in eWAT is low compared to that in the brain, yet specifically increased in eWAT in response to HFD. Loss of CRTC1 by whole‐body germline knockout (CRTC1 KO mice), acute antisense oligonucleotide knockdown in WAT (CRTC1 ASO mice), and tissue‐specific germline knockout in adipose tissue (CRTC1 AKO mice) results in impaired HFD‐responsive eWAT expansion, observed as a ~50% decrease in eWAT size. Diminished capacity for eWAT expansion coincides with elevated lipid accumulation in liver and muscle, hyperglycemia, hyperinsulinemia and glucose intolerance in these animals relative to wildtype or control.CRTC1 knockdown by adenoviral shRNA decreased glucose uptake, increased lipolysis and impeded expression of the key adipogenesis marker PPARγ in differentiated 3T3‐L1 adipocytes. Animal models with decreased CRTC1 expression (CRTC1 KO, ASO and AKO) also exhibited decreased PPARγ expression in eWAT but only on HFD, suggesting that CRTC1 is required for diet‐responsive eWAT remodeling and for maintaining a differentiated state in adipocytes. Supportive of this hypothesis, we observed significantly decreased eWAT FGF1 mRNA expression, plasma FGF1 and WAT FGF1 levels in HFD‐fed animal models of CRTC1 loss relative to control. FGF1 plays a major role in eWAT remodeling and expansion in response to diet: our data indicate that CRTC1 is required for HFD‐mediated upregulation of FGF1. Together, our findings reveal a regulatory axis that is essential for eWAT remodeling and expansion, and that leads to ectopic lipid deposition and insulin resistance when perturbed. Understanding how CRTC1 regulates FGF1 and impacts the PPARγ pathway in eWAT will provide important insights into adipocyte function and into how eWAT expansion is modulated to maintain metabolic homeostasis, allowing identification of new potential targets to treat diseases such as T2D.Support or Funding InformationLife Science Research Foundation Fellowship, Sponsor: Gilead Sciences Inc.; R01 DK083834, PI: Marc Montminy

Suppression of adipocyte differentiation by low-intensity pulsed ultrasound via inhibition of insulin signaling and promotion of CCN family protein 2.

Adipocyte differentiation is regulated by several transcription factors such as the CCAAT/enhancer-binding proteins (C/EBPs) and peroxisome proliferator-activated receptor-γ (PPARγ). Here, we demonstrate that low-intensity pulsed ultrasound (LIPUS) suppressed differentiation into mature adipocytes via multiple signaling pathways. When C3H10T1/2, a mesenchymal stem cell line, was treated with LIPUS (3.0 MHz, 60 mW/cm2 ) for 20 minutes once a day for 4 days during adipogenesis, and both the number of lipid droplets and the gene expression of PPARγ and C/EBPα were significantly decreased. Furthermore, LIPUS treatment decreased the phosphorylation of the insulin receptor and also that of Akt and ERK1/2, which are located downstream of this receptor. Next, we showed that LIPUS suppressed the gene expression of angiotensinogen (AGT), which is an adipokine produced by mature adipocytes, as well as that of angiotensin-converting enzyme1 (ACE1) and angiotensin receptor type 1 (AT1 R) during adipogenesis of pre-adipogenic 3T3-L1 cells. Next, the translocation of Yes-associated protein (YAP) into the nucleus of 3T3-L1 cells was promoted by LIPUS, leading to upregulation of CCN family protein 2 (CCN2), a cellular communication network factor. Moreover, forced expression of CCN2 in 3T3-L1 cells decreased PPARγ gene expression, but it did not increase alkaline phosphatase and osterix gene expression. Finally, gene silencing of CCN2 in C3H10T1/2 cells diminished the effect of LIPUS on the gene expression of PPARγ and C/EBPα. These findings suggest that LIPUS suppressed adipogenesis through inhibition of insulin signaling and decreased PPARγ expression via increased CCN2 production, resulting in a possible decrease of mature adipocytes.

Effect of resveratrol on body composition in adult catch-up growth rats and its mechanism

To observe the effects of resveratrol on body composition in adult catch-up growth rats and to explore the possible mechanism. Eight-week-old male SD rats were randomly divided into 6 groups: normal controls for 4 weeks (NC4) group, caloric restriction for 4 weeks (R4) group, calorie restriction meanwhile resveratrol treatment for 4 weeks (R4E) group, normal controls for 12 weeks (NC12) group, catch-up growth (CUG) group and catch-up growth meanwhile resveratrol treatment for 8 weeks (CUGE) group. At the end of the four-week and twelve-week experimental period, the body weight, muscle and fat content of trunk and whole body, the ratio of trunk to whole body fat were detected, and at the end of twelve-week experimental period, the expression of SIRT1 in skeletal muscle and epididymal adipose tissue, and the expression of PPARγ in epididymal adipose tissue were detected. Compared with NC12 group, the fat content of trunk and whole body and trunk to whole body fat ratio in CUG group were increased significantly, along with the expression of PPARγ in epididymal adipose tissue was increased significantly (P＜0.05), while the muscle content of trunk and whole body, the expression of SIRT1 in skeletal muscle and epididymal adipose tissue in CUG group were decreased significantly compared with NC12 group (P＜0.05 or P＜0.01); compared with CUG group, oral administration of resveratrol distinctly reduced the body fat content and trunk to whole body fat ratio in the CUGE groups, and the expression of PPARγ in epididymal adipose tissue of CUGE group was also significantly decreased (P＜0.05). Meanwhile, the muscle content and the expression of SIRT1 in skeletal muscle and epididymal adipose tissue in CUGE group were significantly increased compared with the CUG group (P＜0.05). Resveratrol can decrease body fat content, increase muscle content and improve abdominal fat accumulation in adult catch-up growth rats, and its mechanism may be associated with increasing SIRT1 expression in skeletal muscle and visceral adipose tissue, decreasing PPARγ expression in visceral adipose tissue.