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TNF-alpha inhibits 3T3-L1 adipocyte differentiation without downregulating the expression of C/EBPbeta and delta
S Kurebayashi1, S Sumitani, S Kasayama
1Department of Molecular Medicine, Osaka University Medical School, Suita, Japan.
Abstract:
Tumor necrosis factor-alpha (TNF-alpha) has been reported to inhibit adipocyte differentiation in which multiple transcription factors including CCAAT enhancer binding proteins (C/EBPs) and peroxisome proliferator-activated receptor (PPAR) gamma play an important role. Induction of C/EBPalpha and PPARgamma, which regulate the expression of many adipocyte-related genes, is dependent on the expression of C/EBPbeta and C/EBPdelta at the early phase of adipocyte differentiation. To elucidate the mechanism by which TNF-alpha inhibits adipocyte differentiation, we examined the effect of TNF-alpha on the expression of these transcription factors in mouse 3T3-L1 preadipocytes. TNF-alpha did not abrogate the induction of C/EBPbeta and C/EBPdelta in response to differentiation stimuli. In fully differentiated adipocytes, TNF-alpha rapidly induced C/EBPbeta and C/EBPdelta, whereas it downregulated the expression of C/EBPalpha and PPARgamma. Our results suggest that TNF-alpha inhibits adipocyte differentiation independently of the downregulation of C/EBPbeta and C/EBPdelta.
Insights
Tumor necrosis factor-alpha (TNF-alpha) inhibits adipocyte differentiation by downregulating key transcription factors like C/EBPalpha and PPARgamma. This occurs independently of early-phase factors C/EBPbeta and C/EBPdelta.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Adipocyte differentiation is crucial for energy homeostasis.
- Tumor necrosis factor-alpha (TNF-alpha) is known to inhibit adipocyte differentiation.
- Transcription factors like CCAAT enhancer binding proteins (C/EBPs) and peroxisome proliferator-activated receptor (PPAR) gamma are critical regulators.
Purpose of the Study:
- To investigate the precise mechanism by which TNF-alpha inhibits adipocyte differentiation.
- To examine the effect of TNF-alpha on the expression of key transcription factors (C/EBPbeta, C/EBPdelta, C/EBPalpha, PPARgamma) during adipogenesis.
- To determine if TNF-alpha's inhibitory effect is mediated by the downregulation of early-phase transcription factors.
Main Methods:
- Utilized mouse 3T3-L1 preadipocytes.
- Induced adipocyte differentiation using standard stimuli.
- Administered TNF-alpha to preadipocytes and differentiated adipocytes.
- Analyzed the expression levels of C/EBPbeta, C/EBPdelta, C/EBPalpha, and PPARgamma via quantitative methods.
Main Results:
- TNF-alpha did not prevent the induction of C/EBPbeta and C/EBPdelta during the early stages of differentiation.
- In fully differentiated adipocytes, TNF-alpha rapidly increased the expression of C/EBPbeta and C/EBPdelta.
- Conversely, TNF-alpha significantly decreased the expression of C/EBPalpha and PPARgamma in differentiated adipocytes.
Conclusions:
- TNF-alpha inhibits adipocyte differentiation through mechanisms that do not involve the downregulation of C/EBPbeta and C/EBPdelta.
- The observed downregulation of C/EBPalpha and PPARgamma by TNF-alpha in differentiated adipocytes is a key finding.
- These results provide insights into the molecular pathways targeted by TNF-alpha during adipogenesis.