Downregulation Of PPARγ Expression Research Articles

PPARγ regulates osteoarthritis chondrocytes apoptosis through caspase-3 dependent mitochondrial pathway

Osteoarthritis (OA) is the most prevalent form of arthritis, characterized by a complex pathogenesis. One of the key factors contributing to its development is the apoptosis of chondrocytes triggered by oxidative stress. Involvement of peroxisome proliferator-activated receptor gamma (PPARγ) has been reported in the regulation of oxidative stress. However, there remains unclear mechanisms that through which PPARγ influences the pathogenesis of OA. The present study aims to delve into the role of PPARγ in chondrocytes apoptosis induced by oxidative stress in the context of OA. Primary human chondrocytes, both relatively normal and OA, were isolated and cultured for the following study. Various assessments were performed, including measurements of cell proliferation, viability and cytotoxicity. Additionally, we examined cell apoptosis, levels of reactive oxygen species (ROS), nitric oxide (NO), mitochondrial membrane potential (MMP) and cytochrome C release. We also evaluated the expression of related genes and proteins, such as collagen type II (Col2a1), aggrecan, inducible nitric oxide synthase (iNOS), caspase-9, caspase-3 and PPARγ. Compared with relatively normal cartilage, the expression of PPARγ in OA cartilage was down-regulated. The proliferation of OA chondrocytes decreased, accompanied by an increase in the apoptosis rate. Down-regulation of PPARγ expression in OA chondrocytes coincided with an up-regulation of iNOS expression, leading to increased secretion of NO, endogenous ROS production, and decrease of MMP levels. Furthermore, we observed the release of cytochrome C, elevated caspase-9 and caspase-3 activities, and reduction of the components of extracellular matrix (ECM) Col2a1 and aggrecan. Accordingly, utilization of GW1929 (PPARγ Agonists) or Z-DEVD-FMK (caspase-3 inhibitor) can protect chondrocytes from mitochondrial-related apoptosis and alleviate the progression of OA. During the progression of OA, excessive oxidative stress in chondrocytes leads to apoptosis and ECM degradation. Activation of PPARγ can postpone OA by down-regulating caspase-3-dependent mitochondrial apoptosis pathway.

Time-Dependent Progression of Metabolic Dysfunction in a Mouse Model of Polycystic Ovary Syndrome

Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women. PCOS is closely linked to metabolic disorders such as obesity, dyslipidemia, systemic insulin resistance (IR), adipose IR and white adipose tissue (WAT) dysfunction. Hyperandrogenism is a clinical hallmark of PCOS, and it plays a fundamental role in the development of metabolic perturbations associated with PCOS. Androgen excess is linked to metabolic dysfunction in multiple tissues, including WAT, in PCOS women. However, data on the disease onset and progression of WAT dysfunction and associated metabolic derangements in PCOS women are lacking. Therefore, we aim to test the hypothesis that the androgen dihydrotestosterone (DHT) induces time-dependent progression of metabolic dysfunction on both the molecular and functional levels in PCOS. This hypothesis will be tested using a well-characterized DHT-induced PCOS mouse model after 2, 4, 8 and 12 weeks of DHT administration. Methods: Three-week old female mice (C57BL/6N) were implanted with Silastic tubes filled with DHT (8 mg, s.c.) or vehicle (n=6/grp) for 2, 4, 8 and 12 weeks. Weekly body weight (BW, gravimetry), body composition (EchoMRI), retroperitoneal fat (RPF) mass (gravimetry) were assessed. Serum leptin, adiponectin and insulin were measured by ELISA, while cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-esterified free fatty acid (NEFA) were measured using a clinical chemistry analyzer. Adipose IR (insulin x NEFA) was calculated. RPF androgen receptor (AR), lipolytic marker adipose triglyceride lipase (ATGL), and adipogenesis marker peroxisome proliferator-activated receptor-γ (PPAR-γ) protein levels were assessed by Western blot. Results: DHT-treated mice showed significant (p<0.05) increases in BW (20.23±0.3 vs 17.63±0.1 g) and lean mass (17.77±0.5 vs 15.50±0.3 g) starting 2 weeks following DHT exposure where higher cholesterol (90.0±2.9 vs 70.0±5.8 mg/dL), insulin (0.51±0.08 vs 0.22±0.03 ng/mL) and adipo-IR (2.5-fold) as well as lower insulin-sensitizing adipokine adiponectin levels (4.9±0.2 vs 9.70±1.1 mg/mL) were also observed compared to vehicle. The increases in RPF mass (105.40±10.3 vs 32.78±1.6 mg) and total fat mass (2.43±0.5 vs 1.09±0.1 g) were only significant starting at weeks 4 and 8, respectively. DHT significantly increased NEFA (1.3- and 1.2-fold, 8- and 12-weeks post DHT, respectively) and leptin (1.5-fold, 12 weeks post DHT). Unexpectedly, DHT increased HDL-C (58.80±1.42 vs 41.40±1.2 mg/dL, 4 weeks post DHT), while decreasing triglycerides (76.17±5.4 vs 107.17±9.4 mg/mL) and LDL-C (6.5±0.8 vs 9.0±0.5 mg/mL) after 8 weeks post DHT. At the molecular level, DHT upregulated RPF AR expression (5-fold) and downregulated ATGL expression by 40% as early as 2 weeks post DHT, and downregulated PPARγ expression by 40% at 4 weeks post DHT indicating early onset of adipose tissue dysfunction. Conclusion and significance: Our findings suggest that some PCOS metabolic traits occur very early following the induction of hyperandrogenemia such as serum adiponectin, insulin and cholesterol, highlighting these markers as an early diagnosis potential biomarkers. The onset of WAT lipolysis and adipogenesis alterations as well as adipo-IR were also early events that may be drivers of disease progression. Therefore, actively screening and managing risk factors for metabolic derangements from early on in PCOS is critical for disease management. Supported by NIH-NIGMS P20GM121334 and NIH-NIMHD P50MD017338 grants and American Heart Association Predoctoral Fellowship 903804. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hypolipidemic effect of dill seed (Anethum graveolens L.) essential oil on lipid profile and peroxisome proliferator-activated receptor- γ expression in hyperlipidemic male rats

Herbal medicines have been suggested for the treatment of hyperlipidemic disorders. The hypolipidemic activities of dill essential oil on lipid profile and peroxisome proliferator-activated receptor-γ (PPARγ) expression in adipose tissue were studied in male rats with hyperlipidemia. The effects were studied and compared of dill essential oil and atorvastatin on serum lipid profile and aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, histopathological damage of liver and PPARγ gene expression in the adipose tissue of male rats with hyperlipidemia. The treatment with dill decreased body weight, serum cholesterol, triglyceride, LDL-C, ALT and AST levels, histopathological damage to the liver and PPARγ expression of adipose tissue, and increased serum HDL-C levels in experimental hyperlipidemic rats compared to the hyperlipidemic control rats, both significantly. The plant and atorvastatin improved hyperlipidemia, attenuated liver tissue damage and down-regulated PPARγ expression. So, dill could be defined as an excellent candidate for treatment of hyperlipidemia.

Effect of the Pulsed Electromagnetic Field Treatment in a Rat Model of Senile Osteoporosis In Vivo.

This study assessed the effects of pulsed electromagnetic fields (PEMF) in a rat model of senile osteoporosis and the underlying molecular events. 24-month-old male Sprague-Dawley (SD) rats were randomly divided into control and PEMF groups (n = 8 per group) using a random digit table, while 3-month-old male SD rats were set as the young-age control group. Rats in the PEMF group were treated by PEMF for 40 min/day for 5 days/week. Bone mineral density/microarchitecture, level of serum bone-specific alkaline phosphatase (BALP), tartrate-resistant acid phosphatase 5b (TRACP5b), and Wnt/β-catenin signaling genes in rat bone marrow cells were then analyzed. The 12-week PEMF intervention showed a significant effect on inhibition of age-induced bone density loss and deterioration of trabecular bone structures in the PEMF group rats versus control rats, that is, the treatment enhanced bone mineral density of the proximal femoral metaphysis and the fifth lumbar (L5) vertebral body and improved the proximal tibia and L4 vertebral body parameters using bone histomorphometry analysis. Furthermore, the BALP level in the bones was significantly increased, but the TRACP5b level was reduced in the PEMF group of rats versus control rats. PEMF also dramatically upregulated expression of Wnt3a, LRP5, β-catenin, and Runx2 but downregulated PPAR-γ expression in the aged rats. The results demonstrated that PEMF could prevent bone loss and architectural deterioration due to the improvement of bone marrow mesenchymal stromal cell differentiation and proliferation abilities and activating the Wnt signaling pathway. Future clinical studies are needed to validate these findings. © 2022 Bioelectromagnetics Society.

Sorghum (<i>Sorghum bicolor</i>) Extract-Induced Adipogenesis Is Independent of PPARγ Ser273 Phosphorylation in 3T3-L1 Adipocytes

Previously we showed that the water-soluble fraction of sorghum extract (SE) improves adipogenesis in 3-isobutyl-1-methylxanthine (IBMX)/dexamethasone/insulin (MDI)/thiazolidinedione (TZD)-induced 3T3-L1 preadipocytes but downregulates genes related to peroxisome proliferator-activated receptor γ (PPARγ) and adipogenesis in both MDI- and MDI/TZD-induced 3T3-L1 adipocytes. In this study, we showed that SE treatment altered the accumulation of stained lipids in 3T3-L1 adipocytes induced by MDI/troglitazone (Tro). Immunoblot analyses indicated that SE treatment reduced adipocyte protein 2 (aP2) expression and induced peroxisome proliferator-activated receptor α (PPARα) protein expression in the presence of Tro in 3T3-L1 adipocytes. MDI/Tro treatment, but not MDI treatment, of 3T3-L1 cells induced PPARγ phosphorylation at Ser273. SE downregulated PPARγ expression in MDI-induced 3T3-L1 adipocytes and did not affect its phosphorylation at Ser273 in MDI- and MDI/Tro-induced 3T3-L1 adipocytes. Therefore, SE likely promotes adipogenesis and lipid metabolism in 3T3-L1 preadipocytes by cooperating with Tro independent of PPARγ Ser273 phosphorylation.

Expression and immunolocalisation of PPARγ in reproductive tissues of rabbits fed n-3 PUFA-enriched diets

Background: Since fatty acids are natural ligands of peroxisome proliferator-activated receptors (PPARs), involved in a wide spectrum of metabolic activities, we explored the protein expression and localisation of PPARγ, as well as susceptibility to lipoperoxidation (LPO), in reproductive tissues of rabbits fed n-3 polyunsaturated fatty acid (PUFA)-enriched diets. Methods: Nine rabbit bucks were divided into three groups and fed different diets: FLAX diet supplemented with 10% extruded flaxseed, FISH diet containing 3.5% fish oil and standard diet as control. Protein expression by western blot analysis, localisation of PPARγ by immunofluorescence and susceptibility to LPO by measuring F2-Isoprostanes (F2-IsoPs) were explored. Results: Down-regulation of PPARγ expression was observed in control rabbit testes compared with FLAX (p < 0.01) and FISH (p < 0.05) dietary groups. On the contrary, an up-regulation in rabbit epididymis was observed in both n-3 PUFAs dietary groups compared with the control (p < 0.001). Immunofluorescent staining of PPARγ showed a strong expression in the interstitial tissue and seminiferous tubules of testes from groups fed n-3 PUFA-enriched diets compared to controls; the PPARγ signal was brighter in the epididymis of controls than in those of rabbits fed n-3 PUFA-enriched diets. Interestingly, F2-IsoP levels were significantly higher in testis and epididymal tissue of control compared to n-3 PUFAs dietary groups (p < 0.001). Conclusion: PPARγ is present in male reproductive tissues, in particular in the epididymis and interstitial testicular tissue. PPARγ expression appears to be influenced by n-3 PUFAs dietary sources and to play a role in supporting sperm maturation. n-3 PUFAs diets, reducing F2-IsoP levels, commonly considered proinflammatory molecules linked to oxidative injuries, may also support PPARγ activity.

Hydroxysafflor yellow A inhibits the proliferation, migration, and invasion of colorectal cancer cells through the PPARγ/PTEN/Akt signaling pathway

ABSTRACT The natural compound Hydroxysafflor yellow A (HSYA) has been demonstrated to exert anti-cancer effect on multiple cancers. This study aimed to clarify the role of HSYA in inhibiting colorectal cancer (CRC) in vitro and the underlying mechanisms. Different concentrations of HSYA (0, 25, 50, and 100 μM) was exposed to HCT116 CRC cells, then cell proliferation, apoptosis, migration, and invasion were estimated by colony formation assay, TUNEL staining, wound-healing, and transwell assays, respectively. Western blotting assay was utilized to observe the expression of proteins involved in cell apoptosis, migration, and peroxisome proliferator-activated receptor γ (PPARγ)/PTEN/Akt signaling, including PCNA, Bax, Bcl-2, cleaved-caspase3, E-cadherin, N-cadherin, vimentin, PPARγ, and phosphorylated (p)-Akt. HCT116 cells that treated with 100 μM HSYA were also pre-treated with PPARγ antagonist, GW9662, or knockdown with PPARγ using short hairpin (sh)-RNA, to down-regulate PPARγ expression. Then, the above functional analysis was repeated. Results demonstrated that HSYA (25, 50 and 100 μM) significantly reduced HCT116 cell viability, but had no effect on the cell viability of human normal intestinal epithelial cell HIEC. HSYA also inhibited colony formation, migration, and invasion but promoted apoptosis of HCT116 cell in a concentration-dependent manner. Besides, the PPARγ/PTEN/Akt signaling was activated upon HSYA treatment. Finally, GW9662 and PPARγ knockdown blocked all the effects of HSYA on HCT116 cells. In conclusion, HSYA could exhibit anti-cancer effect on CRC via activating PPARγ/PTEN/Akt signaling, thereby inhibiting cells proliferation, migration, and invasion in vitro.

The PPARγ-dependent effect of flavonoid luteolin against damage induced by the chemotherapeutic irinotecan in human intestinal cells

Irinotecan (CPT-11) is one of the main agents used to treat colorectal cancer; unfortunately, it is associated with increased intestinal mucositis developing. Luteolin has been shown to prevent damage induced by this chemotherapeutic in mice; thus, in this research, we have investigated luteolin's action mechanism in human intestinal epithelial cells. The potential of luteolin in reducing inflammation and oxidative stress induced by irinotecan in Caco-2 cells was evaluated by PCR through mRNA expression of inflammatory and oxidative genes and by ELISA at the protein level. To assess whether luteolin's ability to control irinotecan-induced damage occurs in a PPARγ dependent manner, experiments were performed on PPARγ downregulated cells. Irinotecan downregulated PPARγ expression and upregulated inflammatory and oxidative genes, while luteolin upregulated PPARγ, HO-1, SOD and decreased expression of IL-1β and iNOS. Interestingly, when the cells were co-stimulated with luteolin and irinotecan, the flavonoid reversed the inflammation and oxidative imbalance evoked by the chemotherapeutic. However, when these experiments were performed in cells downregulated for PPARγ, luteolin lost the capacity to increase PPARγ and reverse the effect of irinotecan in all tested genes, except by IL-1β. The present study showed that the protective effect of luteolin against irinotecan is PPARγ dependent.

Human milk derived peptide AOPDM1 attenuates obesity by restricting adipogenic differentiation through MAPK signalling

BackgroundEmerging evidence revealed peptides within breast milk may be an abundant source of potential candidates for metabolism regulation. Our previous work identified numerous peptides existed in breast milk, but its function has not been validated. Thus, our study aims to screen for novel peptides that have the potential to antagonize obesity and diabetes. MethodsA function screen was designed to identify the candidate peptide and then the peptide effect was validated by assessing lipid storage. Afterwards, the in vivo study was performed in two obese models: high-fat diet (HFD)-induced obese mice and obese ob/ob mice. For mechanism study, a RNA-seq analysis was conducted to explore the pathway that account for the biological function of peptide. ResultsBy performing a small scale screening, a peptide (AVPVQALLLNQ) termed AOPDM1 (anti-obesity peptide derived from breast milk 1) was identified to reduce lipid storage in adipocytes. Further study showed AOPDM1 suppressed adipocyte differentiation by sustaining ERK activity at later stage of differentiation which down-regulated PPARγ expression. In vivo, AOPDM1 effectively reduced fat mass and improved glucose metabolism in high-fat diet (HFD)-induced obese mice and obese ob/ob mice. ConclusionsWe identified a novel peptide AOPDM1 derived from breast milk could restrict adipocyte differentiation and ameliorate obesity through regulating MAPK pathway. General significanceOur findings may provide a potential candidate for the discovery of therapeutic drugs for obesity and type 2 diabetes.

Hypoglycemic Activity of Curcuma mangga Val. Extract via Modulation of GLUT4 and PPAR-γ mRNA Expression in 3T3-L1 Adipocytes.

BackgroundThere would be over 600 million people living with diabetes by 2040 as predicted by the World Health Organization. Diabetes is characterized by raised blood sugar and insulin resistance. Insulin regulates the influx of glucose into the cell by upregulating the glucose transporter type 4 (GLUT4) expression on the plasma membrane. Besides, PPAR-γ also controls the metabolism of glucose in adipose tissues. Curcuma mangga Val., denoted as C. mangga, is a native Indonesian medicinal plant that has many beneficial effects, including an antidiabetic potential.PurposeIn this research, we aimed to disclose the hypoglycemic activity of ethanol extract of C. mangga (EECM) in 3T3-L1 fibroblasts-derived adipocyte cells in regulating glucose uptake as confirmed by the GLUT4 and PPAR-γ gene expression.MethodsThe uptake of glucose was determined using radioactive glucose, while the gene expression of GLUT4, PPAR-γ, and β-actin was quantified using mRNA segregation and real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR).ResultsWe discovered that EECM interventions (200 and 50 μg/mL) increased glucose uptake in lipid-laden 3T3-L1 cells by 14.75 and 8.86 fold compared to the control non-insulin, respectively (p < 0.05). At the same doses, they also increased GLUT4 mRNA expression by 8.41 and 11.18 fold compared to the control non-insulin, respectively (p < 0.05). In contrast, EECM interventions (200 and 50 μg/mL) showed lower levels of PPAR-γ mRNA expression compared to the control metformin, indicating the anti-adipogenic potentials of EECM.ConclusionEECM showed hypoglycemic activity in lipid-laden 3T3-L1 cells by improving glucose ingestion into the cells, which was mediated by increased GLUT4 expression and downregulated PPAR-γ expression.

ALK7 Acts as a Positive Regulator of Macrophage Activation through Down-Regulation of PPARγ Expression.

Aim: Activin receptor-like kinase 7 (ALK7) acts as a key receptor for TGF-β family members, which play important roles in regulating cardiovascular activity. However, ALK7's potential role, and underlying mechanism, in the macrophage activation involved in atherogenesis remain unexplored.Methods: ALK7 expression in macrophages was tested by RT-PCR, western blot, and immunofluorescence co-staining. The loss-of-function strategy using AdshALK7 was performed for functional study. Oil Red O staining was used to observe the foam cell formation, while inflammatory mediators and genes related to cholesterol efflux and influx were determined by RT-PCR and western blot. A PPARγ inhibitor (G3335) was used to reveal whether PPARγ was required for ALK7 to affect macrophage activation.Results: The results exhibited upregulated ALK7 expression in oxidized low-density lipoprotein (Ox-LDL) induced bone marrow derived macrophages (BMDMs) and mouse peritoneal macrophages (MPMs), isolated from ApoE-deficient mice, while ALK7's strong immunoreactivity in BMDMs was observed. ALK7 knockdown significantly attenuated pro-inflammatory, but promoted anti-inflammatory, macrophage markers expression. Additionally, ALK7 silencing decreased foam cell formation, accompanied by the up-regulation of ABCA1 and ABCG1 involved in cholesterol efflux but the down-regulation of CD36 and SR-A implicated in cholesterol influx. Mechanistically, ALK7 knockdown upregulated PPARγ expression, which was required for the ameliorated effect of ALK7 silencing macrophage activation.Conclusions: Our study demonstrated that ALK7 was a positive regulator for macrophage activation, partially through down-regulation of PPARγ expression, which suggested that neutralizing ALK7 might be promising therapeutic strategy for treating atherosclerosis.

Activation of PPARγ reduces N-acetyl-cysteine -induced hypercorticoidism by down-regulating MC2R expression into adrenal glands

We previously demonstrated that oral supplementation with antioxidants induced hyperactivity of hypothalamus-pituitary-adrenal (HPA) axis, attested by hypercorticoidism, through an up-regulation of adrenocorticotrophic hormone (ACTH) receptors (MC2R) in adrenal. This study analyzed the role of peroxisome proliferator-activated receptor (PPAR)-γ on HPA axis hyperactivity induced by N-acetyl-cysteine (NAC). Male Swiss-Webster mice were orally treated with NAC for 1, 3, 5, 10, 15, or 18 consecutive days. The PPAR-γ agonist rosiglitazone and/or antagonist GW9662 were daily-injected i.p. for 5 consecutive days, starting concomitantly with NAC treatment. Rosiglitazone treatment inhibited NAC-induced adrenal hypertrophy and hypercorticoidism. Rosiglitazone also significantly reversed the NAC-induced increase in the MC2R expression in adrenal, but not steroidogenic acute regulatory protein (StAR). NAC treatment reduces the expression of PPARγ in the adrenals, but rosiglitazone did not restore the expression of this cytoprotective gene. In addition, GW9662 blocked the ability of rosiglitazone to decrease plasma corticosterone levels in NAC-treated mice. In conclusion, our findings showed that antioxidant supplementation induced a state of hypercorticoidism through down-regulation of PPARγ expression in the adrenals, in a mechanism probably related to a down-regulation of ACTH receptor expression.

Knockout of E2F1 Inhibits Adipose Stem Cell Proliferation and Differentiation in Fat Transplantation by Repressing Peroxisome Proliferator–Activated Receptor Gamma Expression

Adipose-derived stem cells (ADSCs) possess pluripotent differentiation potential and self-replication ability, which is highly significant in the field of tissue engineering. Cell-assisted lipotransfer (CAL) with ADSCs benefits fat survival. In this study, we focus on the effect of transcription factor E2F1 during CAL. The wild-type (WT) ADSCs were mixed with WT adipocytes, and the E2F1–/– ADSCs were mixed with E2F1–/– adipocytes. Then 2 cell mixtures were inoculated on the back 2 sides of E2F1–/– mice, respectively denoted as the WT group (WT ADSCs + WT adipose cells) and E2F1–/– group (E2F1–/– ADSCs + E2F1–/– adipose cells). At week 4, the fat graft was heavier in the WT group, with less necrotic area, more survival of mature adipocytes, and more proliferating ADSCs, compared with the E2F1–/– group. More capillaries were transformed from ADSCs in the WT group than in the E2F1–/– group. The in vitro protein levels of peroxisome proliferator–activated receptor gamma (PPAR-γ) were higher in WT ADSCs than in E2F1–/– ADSCs. Therefore, these findings suggest that knockout of E2F1 could affect ADSCs to inhibit the survival of fat grafts by downregulating PPAR-γ expression.

An in vitro approach to evaluate the anti-adipogenic effect of Myrica nagi Thunb. Fruit extract on 3T3-L1 adipocyte cell line

BackgroundObesity involves excess accumulation of body fat, leading to metabolic disorders. Although genetic factors involved in obesity have been identified, the influence of phytochemicals on the genes remains to be elucidated. AimsWe aimed to (1) screen extracts of Myrica nagi Thunb. (Myricaceae) by estimating flavonoid, phenol, and tanin content; (2) evaluate enzyme inhibitory activities of the extracts; and (3) analyze the anti-adipogenic activity of the extracts in 3T3L1 cells. MethodsWe evaluated five extracts of M. nagi for their anti-obesity effect by phytochemical screening and enzyme inhibition assays. Furthermore, the extract with the highest inhibitory effect was characterized for its role in adipogenesis using 3T3-L1 cells. ResultsThe methanolic extract of M. nagi (MEMN) showed the highest inhibitory activity against lipase, α-amylase, and α-glucosidase (IC50 values = 91 ± 1.0, 60 ± 4.25, and 100 ± 0.74 μg/mL, respectively). The flavonoid, phenol, and tanin content was highest in the MEMN, with 22.85 ± 1.20, 139.7 ± 11.53, and 1.79 ± 0.12 μg/mL, respectively. The extract also showed anti-oxidant activity with IC50 of 162.22 ± 0.65 μg/mL. Additionally, MEMN did not exert cytotoxicity against 3T3-L1cells; it inhibited adipogenesis and promoted lipolysis of 3T3-L1cells. MEMN at 160 μg/mL concentration reduced triglyceride accumulation in 3T3-L1 cells. Moreover, the extract downregulated PPAR-γ expression. ConclusionsOverall, MEMN possesses potent anti-adipogenic and anti-obesity effects, and thus, can be an alternative herbal treatment for obesity.

MicroRNA-337-3p suppresses cell viability, apoptosis, and autophagy by modulating PPARγ expression in androgen-dependent human prostate cancer

We proposed that autophagy activated through PPARγ in prostate cancer could protect cancer against androgen deprivation. Our MTT and western blotting assay results showed that mimics of miR-337-3p repressed autophagy flux under androgen deprivation, whereas inhibitors had the opposite effect. Neither mimics nor inhibitors influenced cell motility and invasion. miR-337-3p downregulated PPARγ expression in dual luciferase reporter assays and promoted AMPK phosphorylation. The overexpression of PPARγ or AMPK agonists partly diminished the adverse influence of mimics on proliferation and cell autophagy. In a mouse xenograft model, tumors transplanted with LNCap cells having a miR-337-3p deficiency had a significantly larger volume and lower rate of apoptosis than in controls after orchidectomy. Our findings showed that the negative effects of miR-337-3p on cell survival after androgen deprivation through PPARγ degeneration and modulated autophagy could serve as a novel therapeutic target for androgen-dependent prostate cancer and provide a strategy against resistance to anti-androgen therapy.

Analyses of alveolar epithelial injury via lipid-related stress in mammalian target of rapamycin inhibitor-induced lung disease

Although mammalian target of rapamycin inhibitors (mTORi) are used to treat various malignancies, they frequently induce active alveolitis and dyslipidemia. Abnormal lipid metabolism affects alveolar surfactant function and results in pulmonary disorders; however, the pathophysiology of lung injury and its relationship with lipid metabolism remain unknown. We investigated the relationship between lipid metabolism and alveolar epithelial injury, focusing on peroxisome proliferator-activated receptor-γ (PPAR-γ) as a lipid stress-related factor in mTORi-induced lung injury. We clinicopathologically examined three patients with mTORi-induced lung injury. We constructed an mTORi injury mouse model using temsirolimus in mice (30 mg/kg/day), with the vehicle control and bleomycin injury groups. We also constructed a cultured alveolar epithelial cell injury model using temsirolimus (0–40 μM) in the mouse lung epithelial cell line MLE-12 and performed analysis with or without pioglitazone (PPAR-γ agonist) treatment. All three patients had dyslipidemia and lung lesions of hyperplastic pneumocytes with foamy and enlarged changes. In the mouse model, temsirolimus induced significantly higher levels of total cholesterol and free fatty acids in serum and higher levels of surfactant protein D in serum and BAL fluid with an increase in inflammatory cytokines in the lung compared to control. Temsirolimus also induced hyperplastic foamy pneumocytes with increased lipid-associated spots and larger round electron-lucent bodies compared to the control or bleomycin groups in microscopic analyses. Multiple lipid-associated spots within the cytoplasm were also induced by temsirolimus administration in MLE-12 cells. Temsirolimus downregulated PPAR-γ expression in mouse lung and MLE-12 cells but upregulated cleaved caspase-3 in MLE-12 cells. Pioglitazone blocked the upregulated cleaved caspase-3 expression in MLE-12 cells. The pathogenesis of mTORi-induced lung disease may be involved in alveolar epithelial injury, via lipid metabolic stress associated with downregulated PPAR-γ expression. Focusing on the relationship between lipid metabolic stress and alveolar epithelial injury represents a potentially novel approach to the study of pulmonary damage.

Icariin Attenuates M1 Activation of Microglia and Aβ Plaque Accumulation in the Hippocampus and Prefrontal Cortex by Up-Regulating PPARγ in Restraint/Isolation-Stressed APP/PS1 Mice.

BackgroundStudies have shown that psychosocial stress is involved in Alzheimer’s disease (AD) pathogenesis; it induces M1 microglia polarization and production of pro-inflammatory cytokines, leading to neurotoxic outcomes and decreased β-amyloid (Aβ) clearance. Icariin has been proven to be an effective anti-inflammatory agent and to activate peroxisome proliferator-activated receptors gamma (PPARγ) which induces the M2 phenotype in the microglia. However, whether restraint/isolation stress reduces the clearance ability of microglia by priming and polarizing microglia to the M1 phenotype, and the effects of icariin in attenuating the inflammatory response and relieving the pathological changes of AD are still unclear.MethodsAPP/PS1 mice (male, aged 3 months) were randomly divided into a control group, a restraint/isolation stress group, and a restraint/isolation stress + icariin group. The restraint/isolation stress group was subjected to a paradigm to build a depressive animal model. Sucrose preference, open field, elevated plus maze, and Y maze test were used to assess the stress paradigm. The Morris water maze test was performed to evaluate spatial reference learning and memory. Enzyme-linked immunosorbent assay and immunohistochemistry were used to identify the microglia phenotype and Aβ accumulation. Western blotting was used to detect the expression of PPARγ in the hippocampus and prefrontal cortex (PFC).ResultsRestraint/isolation stress induced significant depressive-like behaviors in APP/PS1 mice at 4 months of age and memory impairment at 10 months of age, while 6 months of icariin administration relieved the memory damage. Restraint/isolation stressed mice had elevated pro-inflammatory cytokines, decreased anti-inflammatory cytokines, increased Aβ plaque accumulation and more M1 phenotype microglia in the hippocampus and PFC at 10 months of age, while 6 months of icariin administration relieved these changes. Moreover, restraint/isolation stressed mice had down-regulated PPARγ expression in the hippocampus and PFC at 10 months of age, while 6 months of icariin administration reversed the alteration, especially in the hippocampus.ConclusionRestraint/isolation stress induced depressive-like behaviors and spatial memory damage, over-expression of M1 microglia markers and more severe Aβ accumulation by suppressing PPARγ in APP/PS1 mice. Icariin can be considered a new treatment option as it induces the switch of the microglia phenotype by activating PPARγ.

A single-stranded DNA aptamer against mannose-capped lipoarabinomannan enhances anti-tuberculosis activity of macrophages through downregulation of lipid-sensing nuclear receptor peroxisome proliferator-activated receptor γ expression.

Mannose-capped lipoarabinomannan (ManLAM) is an immunomodulatory epitope of Mycobacterium tuberculosis (Mtb). An aptamer (ZXL1) that specifically binds to ManLAM from the virulent Mtb H37Rv strain was previously generated and it was found that ZXL1 functions as an antagonist, inhibiting the ManLAM-induced immunosuppression of DCs. In the present study, it was found that ZXL1 inhibits Mtb entry into murine macrophages and that ZXL1 enhances IL-1β and IL-12 mRNA expression and cytokine production in ManLAM-treated macrophages but decreases IL-10 production. Inducible nitric oxide synthase expression in macrophages was upregulated in the presence of ZXL1 after stimulation with ManLAM. ZXL1 was also found to inhibit expression of lipid-sensing nuclear receptor peroxisome proliferator-activated receptor γ (PPAR-γ). These results suggest that ZXL1 promotes anti-tuberculosis activity through downregulation of PPAR-γ expression, which may contribute to M1 macrophage polarization and Mtb killing by macrophages.

Inhibition of Adipogenesis Is Involved in the Protective Effects of 1,25-Dihydroxy Vitamin D3 on the Radiation-Injured Bone Marrow Microenvironment in Mice.

To explore the protective effects of 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3) on the bone marrow microenvironment in mice after irradiation and the underlying molecular mechanisms, a total of 150 7-wk-old male BALB/c mice were randomly divided into a normal group, an irradiation (IR) group and an irradiation+1,25-(OH)2D3 (IR+VD3) group. The mice in the IR+VD3 group were treated with 6.0 Gy 60Coγ rays, and 1,25-(OH)2D3 (dissolved in DMSO, 2.5 μg/kg) was administered once per day from 2 d before to 8 d after irradiation. Mice in the IR group were treated with the same dose of γ rays and an equal volume of DMSO. Subsequently, the body weights and the numbers of peripheral white blood cells (WBCs) were measured. Histological analysis of femur bone marrow was conducted to determine the proportion of adipose area as well. Finally, the expression of peroxisome proliferator-activated receptor-gamma (PPARγ) in bone marrow was detected by immunohistochemistry. After irradiation, the percentage of adipose area in the bone marrow was significantly increased, and the WBC number and body weight were markedly reduced. Compared with irradiation alone, the co-administration of 1,25-(OH)2D3 with irradiation markedly attenuated radiation-induced adipogenesis in bone marrow, resulted in fewer bone marrow stromal cells expressing PPARγ and enhanced the recovery of body weight and WBCs. These results indicate that 1,25-(OH)2D3 could accelerate the recovery of body weight and WBCs in irradiated mice and protect the bone marrow by inhibiting radiation-induced adipogenesis via the down-regulation of PPARγ expression.

Activation of peroxisome proliferator-activated receptor gamma in mammary epithelial cells upregulates the expression of tumor suppressor Cyld to mediate growth inhibition and anti-inflammatory effects

Several studies have implicated the downregulation of the tumor suppressor Cyld expression in breast cancer development. However, the mechanisms that regulate Cyld expression in mammary epithelial cells are largely unknown. In order to investigate them, a bioinformatic analysis of the promoter region of Cyld was performed and identified putative nuclear hormone receptor response elements that included peroxisome proliferator-activated receptor gamma (PPAR-γ)-responsive elements. In the present study, we showed that upon activation of the nuclear hormone receptor PPAR-γ by the agonist troglitazone (TZD), there was a significant increase in Cyld mRNA in human mammary epithelial cell lines. The effect of TZD could be attributed to the transactivation of the Cyld promoter as indicated by the upregulation of a luciferase reporter that was driven by the −1995 to +95 region of the human Cyld gene. Furthermore, the upregulation of Cyld expression by TZD was dependent on PPAR-γ since downregulation of PPAR-γ expression by RNAi compromised the induction of Cyld expression by TZD. CYLD induction mediated, at least in part, the TZD-mediated downregulation of tumor necrosis factor α (TNFα)-induced interleukin 8 (IL-8). In addition, downregulation of CYLD compromised the cytotoxic effects of TZD in immortalized mammary epithelial cells. Our results demonstrated that PPAR-γ is a novel regulator of Cyld transcription and identified CYLD as a mediator of the PPAR-γ-dependent anti-inflammatory and anti-proliferative activity in mammary epithelial cells, which underscores its potential to be used as a target for the development of breast cancer therapeutic approaches.