scholarly journals Homeostatic levels of SRC-2 and SRC-3 promote early human adipogenesis

2011 ◽  
Vol 192 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Sean M. Hartig ◽  
Bin He ◽  
Weiwen Long ◽  
Benjamin M. Buehrer ◽  
Michael A. Mancini
Keyword(s):  
Transcriptional Activity ◽  
Adipocyte Differentiation ◽  
Cellular Heterogeneity ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Human Adipocyte ◽  
Lipogenic Gene ◽  
Protein Levels ◽  
High Content Analysis ◽  
Early Human

The related coactivators SRC-2 and SRC-3 interact with peroxisome proliferator activated receptor γ (PPARγ) to coordinate transcriptional circuits to promote adipogenesis. To identify potential coactivator redundancy during human adipogenesis at single cell resolution, we used high content analysis to quantify links between PPARγ, SRC-2, SRC-3, and lipogenesis. Because we detected robust increases and significant cell–cell heterogeneity in PPARγ and lipogenesis, without changes in SRC-2 or SRC-3, we hypothesized that permissive coregulator levels comprise a necessary adipogenic equilibrium. We probed this equilibrium by down-regulating SRC-2 and SRC-3 while simultaneously quantifying PPARγ. Individual or joint knockdown equally inhibits lipid accumulation by preventing lipogenic gene engagement, without affecting PPARγ protein levels. Supporting dominant, pro-adipogenic roles for SRC-2 and SRC-3, SRC-1 knockdown does not affect adipogenesis. SRC-2 and SRC-3 knockdown increases the proportion of cells in a PPARγhi/lipidlo state while increasing phospho-PPARγ–S114, an inhibitor of PPARγ transcriptional activity and adipogenesis. Together, we demonstrate that SRC-2 and SRC-3 concomitantly promote human adipocyte differentiation by attenuating phospho-PPARγ–S114 and modulating PPARγ cellular heterogeneity.

Role of intracellular calcium in human adipocyte differentiation

2000 ◽  
Vol 3 (2) ◽  
pp. 75-82 ◽  
Author(s):  
HANG SHI ◽  
YUAN-DI HALVORSEN ◽  
PAMELA N. ELLIS ◽  
WILLIAM O. WILKISON ◽  
MICHAEL B. ZEMEL
Keyword(s):  
Intracellular Calcium ◽  
Adipocyte Differentiation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Human Adipocyte ◽  
Gpdh Activity ◽  
Early Stages ◽  
Triglyceride Accumulation ◽  
Mild Stimulation

Shi, Hang, Yuan-Di Halvorsen, Pamela N. Ellis, William O. Wilkison, and Michael B. Zemel. Role of intracellular calcium in human adipocyte differentiation. Physiol Genomics 3: 75–82, 2000.—Intracellular calcium ([Ca2+]i) modulates adipocyte lipid metabolism and inhibits the early stages of murine adipogenesis. Consequently, we evaluated effects of increasing [Ca2+]i in early and late stages of human adipocyte differentiation. Increasing [Ca2+]i with either thapsigargin or A23187 at 0–1 h of differentiation markedly suppressed differentiation, with a 40–70% decrease in triglyceride accumulation and glycerol-3 phosphate dehydrogenase (GPDH) activity ( P < 0.005). However, a 1-h pulse of either agent at 47–48 h only modestly inhibited differentiation. Sustained, mild stimulation of Ca2+ influx with either agouti protein or 10 mM KCl-induced depolarization during 0–48 h of differentiation inhibited triglyceride accumulation and GPDH activity by 20–70% ( P < 0.05) and markedly suppressed peroxisome proliferator-activated receptor gamma (PPARγ) expression. These effects were reversed by Ca2+ channel antagonism. In contrast, Ca2+ pulses late in differentiation (71–72 h or 48–72 h) markedly increased these markers of differentiation. Thus increasing [Ca2+]i appears to exert a biphasic regulatory role in human adipocyte differentiation, inhibiting the early stages while promoting the late stage of differentiation and lipid filling.

Regulation of adipocyte differentiation of 3T3-L1 cells by PDZRN3

2013 ◽  
Vol 304 (11) ◽  
pp. C1091-C1097 ◽  
Author(s):  
Takeshi Honda ◽  
Aiko Ishii ◽  
Makoto Inui
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Adipocyte Differentiation ◽  
Early Stage ◽  
Adipogenic Differentiation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Upstream Regulator ◽  
Pparγ Expression

PDZRN3, a member of the PDZRN (or LNX) family of proteins, is essential for the differentiation of mesenchymal stem cells into myotubes, but it plays an inhibitory role in the differentiation of these cells into osteoblasts. Given that mesenchymal stem cells also differentiate into adipocytes, we examined the possible role of PDZRN3 in adipogenesis in mouse 3T3-L1 preadipocytes. The expression of PDZRN3 decreased at both the mRNA and protein levels during adipogenic differentiation. RNAi-mediated depletion of PDZRN3 enhanced the differentiation of 3T3-L1 cells into adipocytes as assessed on the basis of lipid accumulation. The upregulation of aP2 and CCAAT/enhancer-binding protein (C/EBP)-β during adipocyte differentiation was also enhanced in the PDZRN3-depleted cells, as was the induction of peroxisome proliferator-activated receptor-γ (PPARγ), an upstream regulator of aP2 and C/EBPα, at both the mRNA and protein levels. Among transcription factors that control the expression of PPARγ, we found that STAT5b, but not STAT5a, was upregulated in PDZRN3-depleted cells at both mRNA and protein levels. Tyrosine phosphorylation of STAT5b, but not that of STAT5a, was also enhanced at an early stage of differentiation by PDZRN3 depletion. In addition, the expression of C/EBPβ during the induction of differentiation was enhanced at the mRNA and protein levels in PDZRN3-depleted cells. Our results thus suggest that PDZRN3 negatively regulates adipogenesis in 3T3-L1 cells through downregulation of STAT5b and C/EBPβ and consequent suppression of PPARγ expression.

scholarly journals Transcription Suppression of Peroxisome Proliferator-Activated Receptor γ2 Gene Expression by Tumor Necrosis Factor α via an Inhibition of CCAAT/ Enhancer-binding Protein δ during the Early Stage of Adipocyte Differentiation

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4948-4956 ◽  
Author(s):  
Masataka Kudo ◽  
Akira Sugawara ◽  
Akira Uruno ◽  
Kazuhisa Takeuchi ◽  
Sadayoshi Ito
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Gene Transcription ◽  
Adipocyte Differentiation ◽  
Early Stage ◽  
Binding Protein ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Enhancer Binding Protein

Abstract TNFα is known to inhibit adipocyte differentiation and induce insulin resistance. Moreover, TNFα is known to down-regulate peroxisome proliferator-activated receptor (PPAR)γ2, an adipocyte-specific nuclear receptor of insulin-sensitizer thiazolidinediones. To clarify molecular mechanisms of TNFα- mediated PPARγ2 down-regulation, we here examined the effect of TNFα on transcription regulation of PPARγ2 gene expression during the early stage of adipocyte differentiation. 3T3-L1 preadipocytes (2 d after 100% confluent) were incubated in a differentiation mixture (dexamethasone, insulin, 3-isobutyl-1-methlxanthine), with or without 50 ng/ml TNFα, for 24 h. TNFα significantly decreased PPARγ2 expression both at mRNA and protein levels (to ∼40%), as well as aP2 mRNA expression. The mouse PPARγ2 gene promoter region (2.2-kb) was isolated and was used for luciferase reporter assays by transient transfection. TNFα significantly suppressed PPARγ2 gene transcription (to ∼50%), and deletion analyses demonstrated that the suppression was mediated via CCAAT/enhancer-binding protein (C/EBP) binding elements at the −320/−340 region of the promoter. Moreover, TNFα significantly decreased expression of C/EBPδ mRNA and protein levels (to ∼40%). EMSA, using 3T3-L1 cells nuclear extracts with the −320/−340 region as a probe, demonstrated the binding of C/EBPδ to the element, which was significantly decreased by TNFα treatment. Overexpression of CEBP/δ prevented the TNFα-mediated suppression of PPARγ2 transactivation. Taken together, TNFα suppresses PPARγ2 gene transcription by the inhibition of C/EBPδ expression and its DNA binding during the early stage of adipocyte differentiation, which may contribute to the inhibition of adipocyte differentiation, as well as the induction of insulin resistance.

scholarly journals Statins Activate Human PPAR Promoter and Increase PPAR mRNA Expression and Activation in HepG2 Cells

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-11 ◽  
Author(s):  
Makoto Seo ◽  
Ikuo Inoue ◽  
Masaaki Ikeda ◽  
Takanari Nakano ◽  
Seiichiro Takahashi ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Hepg2 Cells ◽  
Promoter Activity ◽  
Transcriptional Activity ◽  
Statin Treatment ◽  
Expression Vectors ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

Statins increase peroxisome proliferator-activated receptor (PPAR) mRNA expression, but the mechanism of this increased PPAR production remains elusive. To examine the regulation of PPAR production, we examined the effect of 7 statins (atorvastatin, cerivastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin) on human PPAR promoter activity, mRNA expression, nuclear protein levels, and transcriptional activity. The main results are as follows. (1) Majority of statins enhanced PPAR promoter activity in a dose-dependent manner in HepG2 cells transfected with the human PPAR promoter. This enhancement may be mediated by statin-induced HNF-4. (2) PPAR mRNA expression was increased by statin treatment. (3) The PPAR levels in nuclear fractions were increased by statin treatment. (4) Simvastatin, pravastatin, and cerivastatin markedly enhanced transcriptional activity in 293T cells cotransfected with acyl-coenzyme A oxidase promoter and PPAR/RXR expression vectors. In summary, these data demonstrate that PPAR production and activation are upregulated through the PPAR promoter activity by statin treatment.

Adipocyte differentiation of 3T3-L1 preadipocytes is dependent on lipoxygenase activity during the initial stages of the differentiation process

2003 ◽  
Vol 375 (3) ◽  
pp. 539-549 ◽  
Author(s):  
Lise MADSEN ◽  
Rasmus K. PETERSEN ◽  
Morten B. SØRENSEN ◽  
Claus JØRGENSEN ◽  
Philip HALLENBORG ◽  
...  
Keyword(s):  
Adipocyte Differentiation ◽  
Critical Evaluation ◽  
Nordihydroguaiaretic Acid ◽  
Whole Body ◽  
Transcriptional Networks ◽  
Peroxisome Proliferator ◽  
The Novel ◽  
Differentiation Process ◽  
Peroxisome Proliferator Activated Receptor ◽  
Brown Adipose

Adipocytes play a central role in whole-body energy homoeostasis. Complex regulatory transcriptional networks control adipogensis, with ligand-dependent activation of PPARγ (peroxisome proliferator-activated receptor γ) being a decisive factor. Yet the identity of endogenous ligands promoting adipocyte differentiation has not been established. Here we present a critical evaluation of the role of LOXs (lipoxygenases) during adipocyte differentiation of 3T3-L1 cells. We show that adipocyte differentiation of 3T3-L1 preadipocytes is inhibited by the general LOX inhibitor NDGA (nordihydroguaiaretic acid) and the 12/15-LOX selective inhibitor baicalein. Baicalein-mediated inhibition of adipocyte differentiation was rescued by administration of rosiglitazone. Treatment with baicalein during the first 4 days of the differentiation process prevented adipocyte differentiation; supplementation with rosiglitazone during the same period was sufficient to rescue adipogenesis. Accordingly, we demonstrate that adipogenic conversion of 3T3-L1 cells requires PPARγ ligands only during the first 4 days of the differentiation process. We show that the baicalein-sensitive synthesis of endogenous PPARγ ligand(s) increases rapidly upon induction of differentiation and reaches a maximum on days 3–4 of the adipocyte differentiation programme. The conventional platelet- and leucocyte-type 12(S)-LOXs and the novel eLOX-3 (epidermis-type LOX-3) are expressed in white and brown adipose tissue, whereas only eLOX-3 is clearly expressed in 3T3-L1 cells. We suggest that endogenous PPARγ ligand(s) promoting adipocyte differentiation are generated via a baicalein-sensitive pathway involving the novel eLOX-3.

scholarly journals Evidence for the Regulatory Role of Lipocalin 2 in High-Fat Diet-Induced Adipose Tissue Remodeling in Male Mice

Endocrinology ◽  
2013 ◽  
Vol 154 (10) ◽  
pp. 3525-3538 ◽  
Author(s):  
Hong Guo ◽  
Merlijn Bazuine ◽  
Daozhong Jin ◽  
Merry M. Huang ◽  
Samuel W. Cushman ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
High Fat Diet ◽  
Adipocyte Differentiation ◽  
Tissue Remodeling ◽  
Peroxisome Proliferator ◽  
Lipocalin 2 ◽  
Peroxisome Proliferator Activated Receptor ◽  
Adipose Tissue Remodeling ◽  
Fat Depot

Lipocalin 2 (Lcn2) has previously been characterized as an adipokine/cytokine playing a role in glucose and lipid homeostasis. In this study, we investigate the role of Lcn2 in adipose tissue remodeling during high-fat diet (HFD)-induced obesity. We find that Lcn2 protein is highly abundant selectively in inguinal adipose tissue. During 16 weeks of HFD feeding, the inguinal fat depot expanded continuously, whereas the expansion of the epididymal fat depot was reduced in both wild-type (WT) and Lcn2−/− mice. Interestingly, the depot-specific effect of HFD on fat mass was exacerbated and appeared more pronounced and faster in Lcn2−/− mice than in WT mice. In Lcn2−/− mice, adipocyte hypertrophy in both inguinal and epididymal adipose tissue was more profoundly induced by age and HFD when compared with WT mice. The expression of peroxisome proliferator-activated receptor-γ protein was significantly down-regulated, whereas the gene expression of extracellular matrix proteins was up-regulated selectively in epididymal adipocytes of Lcn2−/− mice. Consistent with these observations, collagen deposition was selectively higher in the epididymal, but not in the inguinal adipose depot of Lcn2−/− mice. Administration of the peroxisome proliferator-activated receptor-γ agonist rosiglitazone (Rosi) restored adipogenic gene expression. However, Lcn2 deficiency did not alter the responsiveness of adipose tissue to Rosi effects on the extracellular matrix expression. Rosi treatment led to the further enlargement of adipocytes with improved metabolic activity in Lcn2−/− mice, which may be associated with a more pronounced effect of Rosi treatment in reducing TGF-β in Lcn2−/− adipose tissue. Consistent with these in vivo observations, Lcn2 deficiency reduces the adipocyte differentiation capacity of stromal-vascular cells isolated from HFD-fed mice in these cells. Herein Rosi treatment was again able to stimulate adipocyte differentiation to a similar extent in WT and Lcn2−/− inguinal and epididymal stromal-vascular cells. Thus, combined, our data indicate that Lcn2 has a depot-specific role in HFD-induced adipose tissue remodeling.

Sign in / Sign up

Export Citation Format

Share Document