Search Results (108)

Thyroid hormone (TH) plays a vital role in ovarian follicle development, and glucose-regulated protein 78 (GRP78) is involved in these processes, which is regulated by TH. However, the mechanisms are still unclear. To evaluate the possible mechanism of TH on the regulation of GRP78 expression, Cleavage Under Targets and Tagmentation (CUT & Tag) sequencing, luciferase assays, and Electrophoretic Mobility Shift Assays (EMSA) were employed to delineate the binding sites of thyroid hormone receptor β (TRβ) on the GRP78 promoter and to confirm the interactions. Additionally, Co-Immunoprecipitation (Co-IP) and Immunofluorescence (IF) assays were used to investigate the interactions between TRβ and the coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) after triiodothyronine (T₃) treatment with different concentrations. Our findings identified a thyroid hormone response element (TRE) on the GRP78 promoter and demonstrated that TRβ can activate GRP78 expression by interacting with PGC-1α. In order to simulate the condition of hyperthyroidism, granulosa cells (GCs) extracted from rats were treated by T₃ with high concentrations, which decreased the expression of PGC-1α, resulting in decreased expressions of GRP78 and other ferroptosis-related markers such as glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11, xCT), thereby inducing ferroptosis in GCs. Taken together, the present study demonstrates that T₃ induces cellular ferroptosis by binding TRE of the GRP78 promoter in ovarian GCs via TRβ. As a switcher, PGC-1α is also involved in these processes. Full article

Peroxisome proliferator-activated receptors (PPARs), composed of the α/δ/γ subtypes, are ligand-activated nuclear receptors/transcription factors that sense endogenous fatty acids or therapeutic drugs to regulate lipid/glucose metabolism and oxidative stress. PPAR forms a multiprotein complex with a retinoid X receptor and corepressor complex in an unliganded/inactive state, and ligand binding induces the replacement of the corepressor complex with the coactivator complex to initiate the transcription of various genes, including the metabolic and antioxidant ones. We investigated the processes by which the corepressor is replaced with the coactivator or in which two coactivators compete for the PPARα/δ/γ-ligand-binding domains (LBDs) using single- and dual-emission fluorescence resonance energy transfer (FRET) assays. Single-FRET revealed that the respective PPARα/δ/γ-selective agonists (pemafibrate, seladelpar, and pioglitazone) induced the dissociation of the two corepressor peptides, NCoR1 and NCoR2, from the PPARα/δ/γ-LBDs and the recruitment of the two coactivator peptides, CBP and TRAP220. Meanwhile, dual-FRET demonstrated that these processes are simultaneous and that the four coactivator peptides, CBP, TRAP220, PGC1α, and SRC1, were competitively recruited to the PPARα/δ/γ-LBDs with different preferences upon ligand activation. Furthermore, the five newly obtained cocrystal structures using X-ray diffraction, PPARα-LBDs–NCoR2/CBP/TRAP220/PGC1α and PPARγ-LBD–NCoR2, were co-analyzed with those from our previous studies. This illustrates that these coactivators bound to the same PPARα-LBD loci via their consensus LXXLL motifs in the liganded state; that NCoR1/NCoR2 corepressors bound to the same loci via the IXXXL sequences within their consensus LXXXIXXXL motifs in the unliganded state; and that ligand activation induced AF-2 helix 12 formation that interfered with corepressor binding and created a binding space for the coactivator. These PPARα/γ-related biochemical and physicochemical findings highlight the coregulator dynamics on limited PPARα/δ/γ-LBDs loci. Full article

The metabolic poise, or balance, between glycolysis and fatty acid oxidation (FAO) has recently been found to play a critical role in osteogenic differentiation and homeostasis. While simulated microgravity (SMG) is known to impede osteoblast differentiation (OBD) by inhibiting the Wnt/β-catenin pathway, how it affects osteoblast metabolism in this context remains unclear. We previously analyzed the effect of SMG on the differentiation of pre-osteoblast MC3T3-E1 cells and found that it reduced focal adhesion kinase (FAK) activity. This, in turn, downregulated Wnt/β-catenin and two of its downstream targets critical for OBD bone morphogenic protein-2 (BMP2) and type-1 collagen (COL1) formation, leading to a reduction in alkaline phosphatase (ALP) activity and cell matrix mineralization. In this study, we further analyzed how SMG-induced alterations in energy metabolism contribute to the inhibition of OBD in MC3T3-E1 cells. Consistent with our earlier findings, we demonstrated that SMG inhibits OBD by downregulating the collective activity of FAK and the Wnt/β-catenin-BMP2-COL1 transcriptional pathway. Interestingly, we observed that SMG also reduces the abundance of sirtuin-1 (SIRT1), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and carnitine palmitoyl transferase-1α (CPT1A), which are all key metabolic factors regulating mitochondrial number and FAO capacity. Accordingly, we found that the mitochondrial content and FAO potential of MC3T3-E1 cells were lower upon exposure to SMG but were both rescued upon administration of the FAK activator cytotoxic necrotizing factor-1 (CNF1), thereby allowing cells to overcome SMG-induced inhibition of OBD. Taken together, our study indicates that the metabolic regulator SIRT1 may be a new target for reversing SMG-induced bone loss. Full article

Background/Objectives: Type 2 diabetes mellitus (T2DM) is considered a serious risk to public health since its prevalence is rapidly increasing worldwide despite numerous therapeutics. Insulin resistance in T2DM contributes to chronic inflammation and other metabolic abnormalities that generate fat accumulation in the liver, eventually leading to the progression of metabolic dysfunction-associated fatty liver disease (MAFLD). Recently, the possibility that microbial-derived metabolites may alleviate MAFLD through enterohepatic circulation has emerged, but the underlying mechanism remains unclear. In this research, we utilized metabolites obtained from the fermentation of guava leaf extract, which is well-known for its antidiabetic activity, to investigate their effects and mechanisms on MAFLD. Methods: Diabetes was induced by a high-fat diet and streptozotocin injection (80 mg/kg body weight) twice in mice. Subsequently, mice whose fasting blood glucose levels were measured higher than 300 mg/dL were administered with metabolites of Limosilactobacillus fermentum (LF) (50 mg/kg/day) or guava leaf extract fermented by L. fermentum (GFL) (50 mg/kg/day) by gavage for 15 weeks. Results: GFL supplementation mitigated hyperglycemia and hepatic insulin resistance. Moreover, GFL regulated abnormal hepatic histological changes and lipid profiles in diabetic mice. Furthermore, GFL enhanced energy metabolism by activating the sirtuin1 (SIRT1)/proliferator-activated receptor γ coactivator 1α (PGC1α)/peroxisome proliferator-activated receptor (PPAR)-α pathway in diabetic mice. Meanwhile, GFL supplementation suppressed hepatic inflammation in diabetic mice. Conclusions: Taken together, the current study elucidated that GFL could be a potential therapeutic to ameliorate hyperglycemia and hepatic steatosis by improving SIRT1/PGC-1α/ PPAR-α-related energy metabolism in T2DM. Full article

Ubiquitin-specific protease 2 (USP2) maintains mitochondrial integrity in culture myoblasts. In this study, we investigated the molecular mechanisms underlying the protective role of USP2 in mitochondria. The knockout (KO) of the Usp2 gene or the chemical inhibition of USP2 induced a robust accumulation of mitochondrial reactive oxygen species (ROS), accompanied by defects in mitochondrial membrane potential, in C2C12 myoblasts. ROS removal by N-acetyl-L-cysteine restored the mitochondrial dysfunction induced by USP2 deficiency. Comprehensive RT-qPCR screening and following protein analysis indicated that both the genetic and chemical inhibition of USP2 elicited a decrease in uncoupling protein 2 (UCP2) at mRNA and protein levels. Accordingly, the introduction of a Ucp2-expressing construct effectively recovered the mitochondrial membrane potential, entailing an increment in the intracellular ATP level in Usp2KO C2C12 cells. In contrast, USP2 deficiency also decreased peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) protein in C2C12 cells, while it upregulated Ppargc1a mRNA. Overexpression studies indicated that USP2 potentially stabilizes PGC1α in an isopeptidase-dependent manner. Given that PGC1α is an inducer of UCP2 in C2C12 cells, USP2 might ameliorate mitochondrial ROS by maintaining the PGC1α–UCP2 axis in myoblasts. Full article

Sarcopenia, a condition caused by an imbalance between muscle growth and loss, can severely affect the quality of life of elderly patients with metabolic, inflammatory, and cancer diseases. Vigeo, a nuruk-fermented extract of three plants (Eleutherococcus senticosus Maxim (ESM), Achyranthes japonica (Miq.) Nakai (AJN), and Atractylodes japonica Koidzumi (AJK)) has been reported to have anti-osteoporotic effects. However, evidence of the effects of Vigeo on muscle atrophy is not available. Here, in the in vivo model of dexamethasone (Dex)-induced muscle atrophy, Vigeo treatment significantly reversed Dex-induced decreases in calf muscle volume, gastrocnemius (GA) muscle weight, and histological cross-section area. In addition, in mRNA and protein analyses isolated from GA muscle, we observed that Vigeo significantly protected against Dex-induced mouse muscle atrophy by inhibiting protein degradation regulated by atrogin and MuRF-1. Moreover, we demonstrated that Vigeo significantly promoted C2C12 cell line differentiation, as evidenced by the increased width and length of myotubes, and the increased number of fused myotubes with three or more nuclei. Vigeo alleviated the formation of myotubes compared to the control group. Vigeo also significantly increased the mRNA and protein expression of myosin heavy chain (MyHC), MyoD, and myogenin compared to that in the control. Vigeo treatment significantly reduced the mRNA and protein expression of muscle degradation markers atrogin-1 and muscle RING Finger 1 (MuRF-1) in the C2C12 cell line in vitro. Vigeo also activated the AMP-activated protein kinase (AMPK)/silent information regulator 1 (Sirt-1)/peroxisome proliferator-activated receptor-γ co-activator-1α (PGC1α) mitochondrial biogenesis pathway and the Akt/mTOR protein synthesis signaling pathway in Dex-induced myotube atrophy. These findings suggest that Vigeo may have protective effects against Dex-induced muscle atrophy. Therefore, we propose Vigeo as a supplement or potential therapeutic agent to prevent or treat sarcopenia accompanied by muscle atrophy and degeneration. Full article

Skin provides a physical and immune barrier to protect the body from foreign substances, microbial invasion, and desiccation. Aging reduces the barrier function of skin and its rate of repair. Aged skin exhibits decreased mitochondrial function and prolonged low-level inflammation that can be seen in other organs with aging. Peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), an important transcriptional coactivator, plays a central role in modulating mitochondrial function and antioxidant production. Mitochondrial function and inflammation have been linked to epidermal function, but the mechanisms are unclear. The aim of this review is to discuss the mechanisms by which PGC-1α might exert a positive effect on aged skin barrier function. Initially, we provide an overview of the function of skin under physiological and aging conditions, focusing on the epidermis. We then discuss mitochondrial function, oxidative stress, cellular senescence, and inflamm-aging, the chronic low-level inflammation observed in aging individuals. Finally, we discuss the effects of PGC-1α on mitochondrial function, as well as the regulation and role of PGC-1α in the aging epidermis. Full article

The decline in the function and mass of skeletal muscle during aging or other pathological conditions increases the incidence of aging-related secondary diseases, ultimately contributing to a decreased lifespan and quality of life. Much effort has been made to surmise the molecular mechanisms underlying muscle atrophy and develop tools for improving muscle function. Enhancing mitochondrial function is considered critical for increasing muscle function and health. This study is aimed at evaluating the effect of an aqueous extract of Gloiopeltis tenax (GTAE) on myogenesis and muscle atrophy caused by dexamethasone (DEX). The GTAE promoted myogenic differentiation, accompanied by an increase in peroxisome proliferator-activated receptor γ coactivator α (PGC-1α) expression and mitochondrial content in myoblast cell culture. In addition, the GTAE alleviated the DEX-mediated myotube atrophy that is attributable to the Akt-mediated inhibition of the Atrogin/MuRF1 pathway. Furthermore, an in vivo study using a DEX-induced muscle atrophy mouse model demonstrated the efficacy of GTAE in protecting muscles from atrophy and enhancing mitochondrial biogenesis and function, even under conditions of atrophy. Taken together, this study suggests that the GTAE shows propitious potential as a nutraceutical for enhancing muscle function and preventing muscle wasting. Full article

The present study aimed to investigate the impacts of dietary standardized ileal digestible lysine to net energy (SID Lys:NE) ratio on lipid metabolism in pigs fed high-wheat diets. Thirty-six crossbred growing barrows (65.20 ± 0.38 kg) were blocked into two treatment groups, fed high-wheat diets with either a high SID Lys:NE ratio (HR) or a low SID Lys:NE ratio (LR). Each treatment group consisted of three replicates, with six pigs per pen in each replicate. The diminishing dietary SID Lys:NE ratio exhibited no adverse impacts on the carcass trait (p > 0.05) but increased the marbling score of the longissimus dorsi muscle (p < 0.05). Meanwhile, LR diets tended to increase the serum triglyceride concentration (p < 0.1). LR diets upregulated fatty acid transport protein 4 and acetyl-coA carboxylase α expression levels and downregulated the expression level of adipose triglyceride lipase (p < 0.05). LR diets improved energy metabolism via decreasing the expression levels of AMP-activated protein kinase (AMPK) α1, sirtuin 1 (SIRT1), and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) (p < 0.05). Additionally, LR diets stimulated hepatic bile acid synthesis via upregulating the expression levels of cytochrome P450 family 7 subfamily A member 1 and cytochrome P450 family 27 subfamily A member 1, and downregulating farnesol X receptor (FXR) and small heterodimer partner (SHP) expression levels (p < 0.05). A lowered SID Lys:NE ratio affected the colonic microbial composition, characterized by increased relative abundances of YRC22, Parabacteroides, Sphaerochaeta, and Bacteroides, alongside a decreased in the proportion of Roseburia, f_Lachnospiraceae_g_Clostridium, Enterococcus, Shuttleworthia, Exiguobacterium, Corynebacterium, Subdoligranulum, Sulfurospirillum, and Marinobacter (p < 0.05). The alterations in microbial composition were accompanied by a decrease in colonic butyrate concentration (p < 0.1). The metabolomic analysis revealed that LR diets affected primary bile acid synthesis and AMPK signaling pathway (p < 0.05). And the mantel analysis indicated that Parabacteroides, Sphaerochaeta, f_Lachnospiraceae_g_Clostridium, Shuttleworthia, and Marinobacter contributed to the alterations in body metabolism. A reduced dietary SID Lys:NE ratio improves energy metabolism, stimulates lipogenesis, and inhibits lipolysis in finishing pigs by regulating the AMPKα/SIRT1/PGC-1α pathway and the FXR/SHP pathway. Parabacteroides and Sphaerochaeta benefited bile acids synthesis, whereas f_Lachnospiraceae_g_Clostridium, Shuttleworthia, and Marinobacter may contribute to the activation of the AMPK signaling pathway. Overall, body metabolism and colonic microbiota collectively controlled the lipid metabolism in finishing pigs. Full article

Gliomas are the most common primary brain tumors in adults. Despite multidisciplinary treatment approaches, the survival rates for patients with malignant glioma have only improved marginally, and few prognostic biomarkers have been identified. Peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) is a crucial regulator of cancer metabolism, playing a vital role in cancer cell adaptation to fluctuating energy demands. In this study, the clinicopathological roles of PGC-1α in gliomas were evaluated. Employing immunohistochemistry, cell culture, siRNA transfection, cell viability assays, western blot analyses, and in vitro and in vivo invasion and migration assays, we explored the functions of PGC-1α in glioma progression. High PGC-1α expression was significantly associated with an advanced pathological stage in patients with glioma and with poorer overall survival. The downregulation of PGC-1α inhibited glioma cell proliferation, invasion, and migration and altered the expression of oncogenic markers. These results conclusively demonstrated that PGC-1α plays a critical role in maintaining the malignant phenotype of glioma cells and indicated that targeting PGC-1α could be an effective strategy to curb glioma progression and improve patient survival outcomes. Full article

Adipose tissue plays an important role in regulating body temperature and metabolism, with white adipocytes serving as storage units for energy. Recent research focused on the browning of white adipocytes (beige adipocytes), causing thermogenesis and lipolysis. The process of browning is linked to the activation of uncoupling protein (UCP) expression, which can be mediated by the β3 adrenergic receptor pathway. Transcriptional factors, such as peroxisome proliferator activated receptor γ (PPARγ) and PPARγ coactivator 1 alpha, play vital roles in cell fate determination for fat cells. Beige adipocytes have metabolic therapeutic potential to combat diseases such as obesity, diabetes mellitus, and dyslipidemia, owing to their significant impact on metabolic functions. However, the molecular mechanisms that cause the induction of browning are unclear. Therefore, research using animal models and primary culture is essential to provide an understanding of browning for further application in human metabolic studies. Pigs have physiological similarities to humans; hence, they are valuable models for research on adipose tissue. This study demonstrates the browning potential of pig white adipocytes through primary culture experiments. The results show that upregulation of UCP3 gene expression and fragmentation of lipid droplets into smaller particles occur due to isoproterenol stimulation, which activates beta-adrenergic receptor signaling. Furthermore, PPARγ and PGC-1α were found to activate the UCP3 promoter region, similar to that of UCP1. These findings suggest that pigs undergo metabolic changes that induce browning in white adipocytes, providing a promising approach for metabolic research with potential implications for human health. This study offers valuable insights into the mechanism of adipocyte browning using pig primary culture that can enhance our understanding of human metabolism, leading to cures for commonly occurring diseases. Full article

Our study aimed to explore the potential positive effects of cold water exercise on mitochondrial biogenesis and muscle energy metabolism in aging rats. The study involved 32 male and 32 female rats aged 15 months, randomly assigned to control sedentary animals, animals training in cold water at 5 ± 2 °C, or animals training in water at thermal comfort temperature (36 ± 2 °C). The rats underwent swimming training for nine weeks, gradually increasing the duration of the sessions from 2 min to 4 min per day, five days a week. The results demonstrated that swimming in thermally comfortable water improved the energy metabolism of aging rat muscles (increased metabolic rates expressed as increased ATP, ADP concentration, TAN (total adenine nucleotide) and AEC (adenylate energy charge value)) and increased mRNA and protein expression of fusion regulatory proteins. Similarly, cold-water swimming improved muscle energy metabolism in aging rats, as shown by an increase in muscle energy metabolites and enhanced mitochondrial biogenesis and dynamics. It can be concluded that the additive effect of daily activity in cold water influenced both an increase in the rate of energy metabolism in the muscles of the studied animals and an intensification of mitochondrial biogenesis and dynamics (related to fusion and fragmentation processes). Daily activity in warm water also resulted in an increase in the rate of energy metabolism in muscles, but at the same time did not cause significant changes in mitochondrial dynamics. Full article

Obesity is a global health concern. Recent research has suggested that the development of anti-obesity ingredients and functional foods should focus on natural products without side effects. We examined the effectiveness and underlying mechanisms of Brassica juncea extract (BJE) in combating obesity via experiments conducted in both in vitro and in vivo obesity models. In in vitro experiments conducted in a controlled environment, the application of BJE demonstrated the ability to suppress the accumulation of lipids induced by MDI in 3T3-L1 adipocytes. Additionally, it downregulated adipogenic-related proteins peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-α (C/EBP-α), adipocyte protein 2 (aP2), and lipid synthesis-related protein acetyl-CoA carboxylase (ACC). It also upregulated the heat generation protein peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and fatty acid oxidation protein carnitine palmitoyltransferase-1 (CPT-1). The oral administration of BJE decreased body weight, alleviated liver damage, and inhibited the accumulation of lipids in mice with diet-induced obesity resulting from a high-fat diet. The inhibition of lipid accumulation by BJE in vivo was associated with a decreased expression of adipogenic and lipid synthesis proteins and an increased expression of heat generation and fatty acid oxidation proteins. BJE administration improved obesity by decreasing adipogenesis and activating heat generation and fatty acid oxidation in 3T3-L1 cells and in HFD-induced obese C57BL/6J mice. These results suggest that BJE shows potential as a natural method for preventing metabolic diseases associated with obesity. Full article

Three peroxisome proliferator-activated receptor subtypes, PPARα, PPAR(ß/)δ, and PPARγ, exert ligand-dependent transcriptional control in concert with retinoid X receptors (RXRs) on various gene sets harboring PPAR response elements (PPREs) in their promoter regions. Ligand-bound PPAR/RXR complexes do not directly regulate transcription; instead, they recruit multiprotein coactivator complexes to specific genomic regulatory loci to cooperatively activate gene transcription. Several coactivators are expressed in a single cell; however, a ligand-bound PPAR can be associated with only one coactivator through a consensus LXXLL motif. Therefore, altered gene transcription induced by PPAR subtypes/agonists may be attributed to the recruitment of various coactivator species. Using a time-resolved fluorescence resonance energy transfer assay, we analyzed the recruitment of four coactivator peptides (PGC1α, CBP, SRC1, and TRAP220) to human PPARα/δ/γ-ligand-binding domains (LBDs) using eight PPAR dual/pan agonists (bezafibrate, fenofibric acid, pemafibrate, pioglitazone, elafibranor, lanifibranor, saroglitazar, and seladelpar) that are/were anticipated to treat nonalcoholic fatty liver disease. These agonists all recruited four coactivators to PPARα/γ-LBD with varying potencies and efficacy. Only five agonists (bezafibrate, pemafibrate, elafibranor, lanifibranor, and seladelpar) recruited all four coactivators to PPARδ-LBD, and their concentration-dependent responses differed from those of PPARα/γ-LBD. These results indicate that altered gene expression through consensus PPREs by different PPAR subtypes/agonists may be caused, in part, by different coactivators, which may be responsible for the unique pharmacological properties of these PPAR agonists. Full article

High-fat-diet (HFD)-induced obesity parallels hypothalamic inflammation and oxidative stress, but the correlations between them are not well-defined. Here, with mouse models targeting the antioxidant gene LanCL1 in the hypothalamus, we demonstrate that impaired hypothalamic antioxidant defense aggravates HFD-induced hypothalamic inflammation and obesity progress, and these could be improved in mice with elevated hypothalamic antioxidant defense. We also show that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a critical transcriptional coactivator, is implicated in regulating hypothalamic LanCL1 transcription, in collaboration with SP1 through a direct interaction, in response to HFD-induced palmitic acid (PA) accumulation. According to our results, when exposed to HFD, mice undergo a process of overwhelming hypothalamic antioxidant defense; short-time HFD exposure induces ROS production to activate PGC-1α and elevate LanCL1-mediated antioxidant defense, while long-time exposure promotes ubiquitin-mediated PGC-1α degradation and suppresses LanCL1 expression. Our findings show the critical importance of the hypothalamic PGC-1α-SP1-LanCL1 axis in regulating HFD-induced obesity, and provide new insights describing the correlations of hypothalamic inflammation and oxidative stress during this process. Full article