Constitutive activation of p46JNK2 is indispensable for C/EBPδ induction in the initial stage of adipogenic differentiation

2017 ◽  
Vol 474 (20) ◽  
pp. 3421-3437 ◽  
Author(s):  
Joji Kusuyama ◽  
Tomokazu Ohnishi ◽  
Kenjiro Bandow ◽  
Muhammad Subhan Amir ◽  
Kaori Shima ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Energy Homeostasis ◽  
Early Stage ◽  
Adipogenic Differentiation ◽  
Endocrine System ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Initial Stage

Adipogenic differentiation plays a vital role in energy homeostasis and endocrine system. Several transcription factors, including peroxisome proliferator-activated receptor gamma 2 and CCAAT–enhancer-binding protein (C/EBP) α, β, and δ, are important for the process, whereas the stage-specific intracellular signal transduction regulating the onset of adipogenesis remains enigmatic. Here, we explored the functional role of c-jun N-terminal kinases (JNKs) in adipogenic differentiation using in vitro differentiation models of 3T3-L1 cells and primary adipo-progenitor cells. JNK inactivation with either a pharmacological inhibitor or JNK2-specific siRNA suppressed adipogenic differentiation, characterized by decreased lipid droplet appearance and the down-regulation of Adiponectin, fatty acid protein 4 (Fabp4), Pparg2, and C/ebpa expressions. Conversely, increased adipogenesis was observed by the inducible overexpression of p46JNK2 (JNK2-1), whereas it was not observed by that of p54JNK2 (JNK2-2), indicating a distinct role of p46JNK2. The essential role of JNK appears restricted to the early stage of adipogenic differentiation, as JNK inhibition in the later stages did not influence adipogenesis. Indeed, JNK phosphorylation was significantly induced at the onset of adipogenic differentiation. As for the transcription factors involved in early adipogenesis, JNK inactivation significantly inhibited the induction of C/ebpd, but not C/ebpb, during the initial stage of adipogenic differentiation. JNK activation increased C/ebpd mRNA and protein expression through the induction and phosphorylation of activating transcription factor 2 (ATF2) that binds to a responsive element within the C/ebpd gene promoter region. Taken together, these data indicate that constitutive JNK activity is specifically required for the initial stage differentiation events of adipocytes.

scholarly journals Interferon-Stimulated Gene ISG12b1 Inhibits Adipogenic Differentiation and Mitochondrial Biogenesis in 3T3-L1 Cells

Endocrinology ◽  
2008 ◽  
Vol 150 (3) ◽  
pp. 1217-1224 ◽  
Author(s):  
Bing Li ◽  
Jonghyun Shin ◽  
Kichoon Lee
Keyword(s):  
Mitochondrial Biogenesis ◽  
Adipogenic Differentiation ◽  
Peroxisome Proliferator ◽  
Mitochondrial Transcription ◽  
Peroxisome Proliferator Activated Receptor ◽  
And Function ◽  
Adipocyte Development

Microarray analysis was performed to find a new group of genes or pathways that might be important in adipocyte development and metabolism. Among them, a mouse interferon-stimulated gene 12b1 (ISG12b1) is expressed at a 400-fold higher level in adipocytes compared with stromal-vascular cells. It is predominantly expressed in adipose tissue among other tissues we tested. Developmentally, ISG12b1 mRNA expression was initially inhibited followed by a dramatic induction during both in vivo and in vitro adipogenic differentiation. Adenovirus-mediated overexpression of ISG12b1 inhibited adipogenic differentiation in 3T3-L1 cells as shown by decreased lipid staining with Oil-Red-O and reduction in adipogenic marker proteins including peroxisome proliferator-activated receptor-γ (PPARγ), and CCAAT/enhancer-binding protein-α (C/EBPα). Our bioinformatics analysis for the predicted localization of ISG12b1 protein suggested the mitochondrial localization, which was confirmed by the colocalization of hemagglutinin-tagged ISG12b1 protein with mitochondrial marker MitoTracker. In addition, ISG12b1 protein was exclusively detected in protein extract from the fractionated mitochondria by Western blot analysis. Furthermore, overexpression of ISG12b1 in adipocytes reduced mitochondrial DNA content and gene expression of mitochondrial transcription factor A (mtTFA), nuclear respiratory factor 1 (NRF1), and cytochrome oxidase II, suggesting an inhibitory role of ISG12b1 in mitochondrial biogenesis and function. Activation of mitochondrial biogenesis and function by treatment with PPARγ and PPARα agonists in 3T3-L1 cells and cold exposure in mice induced mitochondrial transcription factors and reduced ISG12 expression. These data demonstrated that mitochondrial-localized ISG12b1 protein inhibits adipocyte differentiation and mitochondrial biogenesis and function, implying the important role of mitochondrial function in adipocyte development and associated diseases. ISG12b1 is predominantly expressed in adipocytes and dramatically induced at the terminal stage of adipogenesis. Functionally, mitochondria-localized ISG12b1 inhibits adipogenic differentiation and mitochondria biogenesis.

scholarly journals Role of Osteoprotegerin (OPG) in Bone Marrow Adipogenesis

2016 ◽  
Vol 40 (3-4) ◽  
pp. 681-692 ◽  
Author(s):  
Lili Zhang ◽  
Mengmeng Liu ◽  
Xiaokang Zhou ◽  
Yi Liu ◽  
Bo Jing ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Osteogenic Differentiation ◽  
Adipogenic Differentiation ◽  
Tumor Necrosis Factor Receptor ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Marrow Cavity ◽  
Ppar Γ

Background/Aims: Bone marrow adipogenesis is one of the major characteristics of aged bone. Bone marrow mesenchymal stem cells (BMMSCs) prefer to differentiate into adipocytes instead of osteoblasts in the bone marrow cavity in aged hosts. The mechanism of formation and function of adipocytes in aged bone marrow needs further investigation. Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor (TNFR) super family, and it can inhibit the activities of osteoclasts. We found that adipocyte numbers increased in the bone marrow of Opg knockout mice. In this study, we investigated the role of OPG in the differentiation of BMMSCs and bone marrow adipogenesis. Methods: Histological analyses were performed on the bone tissues of Opg knockout (Opg-KO) and wild-type (WT) mice of different ages. BMMSCs obtained from mice were cultured in vitro to evaluate their differentiation abilities. Results: With aging, the expression of Opg in the bone marrow of WT mice markedly decreased, but that of the adipogenic specific transcription factor peroxisome proliferator-activated receptor γ (Ppar-γ) increased. Adipocytes formed in the bone marrow of Opg-KO mice at a relative young age, and the number of adipocytes increased dramatically with age. Compared with the WT control, the osteogenic differentiation of Opg-KO BMMSCs decreased, but the adipogenic differentiation increased. Moreover, exogenous OPG could inhibit the adipogenic differentiation and promote the osteogenic differentiation of Opg-KO BMMSCs in vitro. Conclusions: OPG plays an important role in regulating BMMSC differentiation and bone marrow adipogenesis.

scholarly journals The Novel Role of PGC1α in Bone Metabolism

2021 ◽  
Vol 22 (9) ◽  
pp. 4670
Author(s):  
Cinzia Buccoliero ◽  
Manuela Dicarlo ◽  
Patrizia Pignataro ◽  
Francesco Gaccione ◽  
Silvia Colucci ◽  
...  
Keyword(s):  
Bone Metabolism ◽  
Osteoblastic Differentiation ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Sirtuin 3 ◽  
Peroxisome Proliferator Activated Receptor ◽  
Increased Risk

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) is a protein that promotes transcription of numerous genes, particularly those responsible for the regulation of mitochondrial biogenesis. Evidence for a key role of PGC1α in bone metabolism is very recent. In vivo studies showed that PGC1α deletion negatively affects cortical thickness, trabecular organization and resistance to flexion, resulting in increased risk of fracture. Furthermore, in a mouse model of bone disease, PGC1α activation stimulates osteoblastic gene expression and inhibits atrogene transcription. PGC1α overexpression positively affects the activity of Sirtuin 3, a mitochondrial nicotinammide adenina dinucleotide (NAD)-dependent deacetylase, on osteoblastic differentiation. In vitro, PGC1α overexpression prevents the reduction of mitochondrial density, membrane potential and alkaline phosphatase activity caused by Sirtuin 3 knockdown in osteoblasts. Moreover, PGC1α influences the commitment of skeletal stem cells towards an osteogenic lineage, while negatively affects marrow adipose tissue accumulation. In this review, we will focus on recent findings about PGC1α action on bone metabolism, in vivo and in vitro, and in pathologies that cause bone loss, such as osteoporosis and type 2 diabetes.

Sirtuin 1 is involved in oleic acid-induced calf hepatocyte steatosis via alterations in lipid metabolism-related proteins

2021 ◽  
Vol 99 (10) ◽  
Author(s):  
Hongyan Ding ◽  
Yu Li ◽  
Leihong Liu ◽  
Ning Hao ◽  
Suping Zou ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Mrna Abundance ◽  
Sirtuin 1 ◽  
Peroxisome Proliferator ◽  
Acetyl Coa Carboxylase ◽  
Peroxisome Proliferator Activated Receptor ◽  
Lower Protein ◽  
Tag Accumulation

Abstract Sirtuin 1 (SIRT1), an NAD-dependent protein deacetylase, plays a central role in the control of lipid metabolism in nonruminants. However, the role of SIRT1 in hepatic lipid metabolism in dairy cows with fatty liver is not well known. Thus, we used isolated primary bovine hepatocytes to determine the role of SIRT1 in protecting cells against oleic acid (OA)-induced steatosis. Recombinant adenoviruses to overexpress (AD-GFP-SIRT1-E) or knockdown (AD-GFP-SIRT1-N) SIRT1 were used for transduction of hepatocytes. Calf hepatocytes isolated from five female calves (1 d old, 30 to 40 kg) were used to determine both time required and the lowest dose of OA that could induce triacylglycerol (TAG) accumulation. Analyses indicated that 0.25 mM OA for 24 h was suitable to induce TAG accumulation. In addition, OA not only led to an increase in TAG, but also upregulated mRNA and protein abundance of sterol regulatory element-binding transcription factor 1 (SREBF1) and downregulated SIRT1 and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PPARGC1A). Thus, these in vitro conditions were deemed optimal for subsequent experiments. Calf hepatocytes were cultured and incubated with OA (0.25 mM) for 24 h, followed by adenoviral AD-GFP-SIRT1-E or AD-GFP-SIRT1-N transduction for 48 h. Overexpression of SIRT1 led to greater protein and mRNA abundance of SIRT1 along with fatty acid oxidation-related genes including PPARGC1A, peroxisome proliferator-activated receptor alpha (PPARA), retinoid X receptor α (RXRA), and ratio of phospho-acetyl-CoA carboxylase alpha (p-ACACA)/total acetyl-CoA carboxylase alpha (ACACA). In contrast, it resulted in lower protein and mRNA abundance of genes related to lipid synthesis including SREBF1, fatty acid synthase (FASN), apolipoprotein E (APOE), and low-density lipoprotein receptor (LDLR). The concentration of TAG decreased due to SIRT1 overexpression. In contrast, silencing SIRT1 led to lower protein and mRNA abundance of SIRT1, PPARGC1A, PPARA, RXRA, and greater protein and mRNA abundance of SREBF1, FASN, APOE, and LDLR. Further, those responses were accompanied by greater content of cellular TAG and total cholesterol (TC). Overall, data from these in vitro studies indicated that SIRT1 is involved in the regulation of lipid metabolism in calf hepatocytes subjected to an increase in the supply of OA. Thus, it is possible that alterations in SIRT1 abundance and activity in vivo contribute to development of fatty liver in dairy cows.

scholarly journals Role of Hyaluronan in Human Adipogenesis: Evidence from in-Vitro and in-Vivo Studies

2019 ◽  
Vol 20 (11) ◽  
pp. 2675 ◽  
Author(s):  
Nicholas Wilson ◽  
Robert Steadman ◽  
Ilaria Muller ◽  
Mohd Draman ◽  
D. Aled Rees ◽  
...  
Keyword(s):  
Stem Cell Differentiation ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Synthesis Inhibitor ◽  
Peroxisome Proliferator Activated Receptor ◽  
Inhibitory Role ◽  
The Impact

Hyaluronan (HA), an extra-cellular matrix glycosaminoglycan, may play a role in mesenchymal stem cell differentiation to fat but results using murine models and cell lines are conflicting. Our previous data, illustrating decreased HA production during human adipogenesis, suggested an inhibitory role. We have investigated the role of HA in adipogenesis and fat accumulation using human primary subcutaneous preadipocyte/fibroblasts (PFs, n = 12) and subjects of varying body mass index (BMI). The impact of HA on peroxisome proliferator-activated receptor gamma (PPARγ) expression was analysed following siRNA knockdown or HA synthase (HAS)1 and HAS2 overexpression. PFs were cultured in complete or adipogenic medium (ADM) with/without 4-methylumbelliferone (4-MU = HA synthesis inhibitor). Adipogenesis was evaluated using oil red O (ORO), counting adipogenic foci, and measurement of a terminal differentiation marker. Modulating HA production by HAS2 knockdown or overexpression increased (16%, p < 0.04) or decreased (30%, p = 0.01) PPARγ transcripts respectively. The inhibition of HA by 4-MU significantly enhanced ADM-induced adipogenesis with 1.52 ± 0.18- (ORO), 4.09 ± 0.63- (foci) and 2.6 ± 0.21-(marker)-fold increases compared with the controls, also increased PPARγ protein expression (40%, (p < 0.04)). In human subjects, circulating HA correlated negatively with BMI and triglycerides (r = −0.396 (p = 0.002), r = −0.269 (p = 0.038), respectively), confirming an inhibitory role of HA in human adipogenesis. Thus, enhancing HA action may provide a therapeutic target in obesity.

scholarly journals Peroxisome Proliferator-Activated Receptor γ and PGC-1α in Cancer: Dual Actions as Tumor Promoter and Suppressor

PPAR Research ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Seong-Hoon Yun ◽  
Sang-Heum Han ◽  
Joo-In Park
Keyword(s):  
Metabolic Pathways ◽  
Energy Homeostasis ◽  
Tumor Promoter ◽  
Clinical Implications ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Interacting Protein ◽  
Action Mechanisms ◽  
Important Regulator

Peroxisome proliferator-activated receptor γ (PPARγ) is part of a nuclear receptor superfamily that regulates gene expression involved in cell differentiation, proliferation, immune/inflammation response, and lipid metabolism. PPARγ coactivator-1α (PGC-1α), initially identified as a PPARγ-interacting protein, is an important regulator of diverse metabolic pathways, such as oxidative metabolism and energy homeostasis. The role of PGC-1α in diabetes, neurodegeneration, and cardiovascular disease is particularly well known. PGC-1α is also now known to play important roles in cancer, independent of the role of PPARγ in cancer. Though many researchers have studied the expression and clinical implications of PPARγ and PGC-1α in cancer, there are still many controversies about the role of PPARγ and PGC-1α in cancer. This review examines and summarizes some recent data on the role and action mechanisms of PPARγ and PGC-1α in cancer, respectively, particularly the recent progress in understanding the role of PPARγ in several cancers since our review was published in 2012.

scholarly journals Natural and Synthetic PPARγ Ligands in Tumor Microenvironment: A New Potential Strategy against Breast Cancer

2020 ◽  
Vol 21 (24) ◽  
pp. 9721
Author(s):  
Giuseppina Augimeri ◽  
Luca Gelsomino ◽  
Pierluigi Plastina ◽  
Cinzia Giordano ◽  
Ines Barone ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Microenvironment ◽  
Complex Disease ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Extracellular Matrix Components ◽  
Potential Strategy

Multiple lines of evidence indicate that activation of the peroxisome proliferator-activated receptor γ (PPARγ) by natural or synthetic ligands exerts tumor suppressive effects in different types of cancer, including breast carcinoma. Over the past decades a new picture of breast cancer as a complex disease consisting of neoplastic epithelial cells and surrounding stroma named the tumor microenvironment (TME) has emerged. Indeed, TME is now recognized as a pivotal element for breast cancer development and progression. Novel strategies targeting both epithelial and stromal components are under development or undergoing clinical trials. In this context, the aim of the present review is to summarize PPARγ activity in breast TME focusing on the role of this receptor on both epithelial/stromal cells and extracellular matrix components of the breast cancer microenvironment. The information provided from the in vitro and in vivo research indicates PPARγ ligands as potential agents with regards to the battle against breast cancer.

scholarly journals Identification of a Functional Peroxisome Proliferator-Activated Receptor Response Element in the Rat Catalase Promoter

2002 ◽  
Vol 16 (12) ◽  
pp. 2793-2801 ◽  
Author(s):  
Geoffrey D. Girnun ◽  
Frederick E. Domann ◽  
Steven A. Moore ◽  
Mike E. C. Robbins
Keyword(s):  
Reactive Oxygen Species ◽  
Transcription Factors ◽  
Inflammatory Response ◽  
Reactive Oxygen ◽  
Peroxisome Proliferator ◽  
Oxygen Species ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Promoter Deletion Analysis

Abstract Peroxisomal proliferator-activated receptor (PPAR)γ has been shown to decrease the inflammatory response via transrepression of proinflammatory transcription factors. However, the identity of PPARγ responsive genes that decrease the inflammatory response has remained elusive. Because generation of the reactive oxygen species hydrogen peroxide (H2O2) plays a role in the inflammatory process and activation of proinflammatory transcription factors, we wanted to determine whether the antioxidant enzyme catalase might be a PPARγ target gene. We identified a putative PPAR response element (PPRE) containing the canonical direct repeat 1 motif, AGGTGA-A-AGTTGA, in the rat catalase promoter. In vitro translated PPARγ and retinoic X receptor-α proteins were able to bind to the catalase PPRE. Promoter deletion analysis revealed that the PPRE was functional, and a heterologous promoter construct containing a multimerized catalase PPRE demonstrated that the PPRE was necessary and sufficient for PPARγ-mediated activation. Treatment of microvascular endothelial cells with PPARγ ligands led to increases in catalase mRNA and activity. These results demonstrate that PPARγ can alter catalase expression; this occurs via a PPRE in the rat catalase promoter. Thus, in addition to transrepression of proinflammatory transcription factors, PPARγ may also be modulating catalase expression, and hence down-regulating the inflammatory response via scavenging of reactive oxygen species.

scholarly journals LKB1 signalling attenuates early events of adipogenesis and responds to adipogenic cues

2014 ◽  
Vol 53 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Amélie Gormand ◽  
Christine Berggreen ◽  
Lahouari Amar ◽  
Emma Henriksson ◽  
Ingrid Lund ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Histone Deacetylases ◽  
Fatty Acid Synthase ◽  
Nuclear Translocation ◽  
Adipogenic Differentiation ◽  
Camp Response Element Binding ◽  
Dominant Negative ◽  
Hormone Sensitive Lipase ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

cAMP-response element-binding protein (CREB) is required for the induction of adipogenic transcription factors such as CCAAT/enhancer-binding proteins (C/EBPs). Interestingly, it is known from studies in other tissues that LKB1 and its substrates AMP-activated protein kinase (AMPK) and salt-inducible kinases (SIKs) negatively regulate gene expression by phosphorylating the CREB co-activator CRTC2 and class IIa histone deacetylases (HDACs), which results in their exclusion from the nucleus where they co-activate or inhibit their targets. In this study, we show that AMPK/SIK signalling is acutely attenuated during adipogenic differentiation of 3T3-L1 preadipocytes, which coincides with the dephosphorylation and nuclear translocation of CRTC2 and HDAC4. When subjected to differentiation, 3T3-L1 preadipocytes in which the expression of LKB1 was stably reduced using shRNA (Lkb1-shRNA), as well as Lkb1-knockout mouse embryonic fibroblasts (Lkb1−/− MEFs), differentiated more readily into adipocyte-like cells and accumulated more triglycerides compared with scrambled-shRNA-expressing 3T3-L1 cells or Wt MEFs. In addition, the phosphorylation of CRTC2 and HDAC4 was reduced, and the mRNA expression of adipogenic transcription factors Cebpa, peroxisome proliferator-activated receptor γ (Pparg) and adipocyte-specific proteins such as hormone-sensitive lipase (HSL), fatty acid synthase (FAS), aP2, GLUT4 and adiponectin was increased in the absence of LKB1. The mRNA and protein expression of Ddit3/CHOP10, a dominant-negative member of the C/EBP family, was reduced in Lkb1-shRNA-expressing cells, providing a potential mechanism for the up-regulation of Pparg and Cebpa expression. These results support the hypothesis that LKB1 signalling keeps preadipocytes in their non-differentiated form.

scholarly journals The PPARγ ligand rosiglitazone attenuates hypoxia-induced endothelin signaling in vitro and in vivo

2011 ◽  
Vol 301 (6) ◽  
pp. L881-L891 ◽  
Author(s):  
Bum-Yong Kang ◽  
Jennifer M. Kleinhenz ◽  
Tamara C. Murphy ◽  
C. Michael Hart
Keyword(s):  
Transcription Factors ◽  
Hypoxia Inducible Factor ◽  
Cell Counting ◽  
Mouse Lung ◽  
Therapeutic Effects ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

Peroxisome proliferator-activated receptor (PPAR) γ activation attenuates hypoxia-induced pulmonary hypertension (PH) in mice. The current study examined the hypothesis that PPARγ attenuates hypoxia-induced endothelin-1 (ET-1) signaling to mediate these therapeutic effects. To test this hypothesis, human pulmonary artery endothelial cells (HPAECs) were exposed to normoxia or hypoxia (1% O2) for 72 h and treated with or without the PPARγ ligand rosiglitazone (RSG, 10 μM) during the final 24 h of exposure. HPAEC proliferation was measured with MTT assays or cell counting, and mRNA and protein levels of ET-1 signaling components were determined. To explore the role of hypoxia-activated transcription factors, selected HPAECs were treated with inhibitors of hypoxia-inducible factor (HIF)-1α (chetomin) or nuclear factor (NF)-κB (caffeic acid phenethyl ester, CAPE). In parallel studies, male C57BL/6 mice were exposed to normoxia (21% O2) or hypoxia (10% O2) for 3 wk with or without gavage with RSG (10 mg·kg−1·day−1) for the final 10 days of exposure. Hypoxia increased ET-1, endothelin-converting enzyme-1, and endothelin receptor A and B levels in mouse lung and in HPAECs and increased HPAEC proliferation. Treatment with RSG attenuated hypoxia-induced activation of HIF-1α, NF-κB activation, and ET-1 signaling pathway components. Similarly, treatment with chetomin or CAPE prevented hypoxia-induced increases in HPAEC ET-1 mRNA and protein levels. These findings indicate that PPARγ activation attenuates a program of hypoxia-induced ET-1 signaling by inhibiting activation of hypoxia-responsive transcription factors. Targeting PPARγ represents a novel therapeutic strategy to inhibit enhanced ET-1 signaling in PH pathogenesis.

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