TY - JOUR
T1 - Specific inhibitors of p38 mitogen-activated protein kinase block 3T3- L1 adipogenesis
AU - Engelman, Jeffrey A.
AU - Lisanti, Michael P.
AU - Scherer, Philipp E.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1999/11/27
Y1 - 1999/11/27
N2 - SB203580 and SB202190, pyridinyl imidazoles that selectively inhibit p38 mitogen-activated protein (MAP) kinase, are widely utilized to assess the physiological roles of p38. Here, we demonstrate that treatment of 3T3-L1 fibroblasts with these p38 MAP kinase inhibitors prevents their differentiation into adipocytes as judged by an absence of lipid accumulation, a lack of expression of adipocyte-specific genes, and a fibroblastic morphological appearance. In 3T3-L1 fibroblasts and developing adipocytes, p38 is active, p38 activity decreases dramatically during later stages of differentiation. In accordance with the time course of p38 activity, p38 inhibitor treatment during only the early stages of differentiation is sufficient to block adipogenesis. In addition, we constructed a 3T3-L1 cell line harboring an inducible dominant negative p38 mutant. The induction of this dominant negative mutant of p38 prevents adipocyte differentiation. Thus, it is likely that the antiadipogenic activity of SB203580 and 8B202190 is indeed due to inhibition of p38 MAP kinase. This study points out that CCAAT/enhancer-binding protein β (C/EBPβ), a transcription factor critical for the initial stages of 3T3-L1 adipogenesis, bears a consensus site for p38 phosphorylation and serves as a substrate for p38 MAP kinase in vitro. Although the induction of C/EBPβ is not significantly altered in the presence of the p38 inhibitor, the amount of in vivo phosphorylated C/EBPβ is reduced by SB203580. The transcriptional induction of PPARγ, a gene whose expression is induced by C/EBPβ, and a factor critically involved in terminal differentiation of adipocytes, is impaired in the presence of p38 inhibitors. Thus, transcription factors such as C/EBPβ that promote adipocyte differentiation may be p38 targets during adipogenesis. Collectively, the data in this study suggest that p38 MAP kinase activity is important for proper 3T3-L1 differentiation.
AB - SB203580 and SB202190, pyridinyl imidazoles that selectively inhibit p38 mitogen-activated protein (MAP) kinase, are widely utilized to assess the physiological roles of p38. Here, we demonstrate that treatment of 3T3-L1 fibroblasts with these p38 MAP kinase inhibitors prevents their differentiation into adipocytes as judged by an absence of lipid accumulation, a lack of expression of adipocyte-specific genes, and a fibroblastic morphological appearance. In 3T3-L1 fibroblasts and developing adipocytes, p38 is active, p38 activity decreases dramatically during later stages of differentiation. In accordance with the time course of p38 activity, p38 inhibitor treatment during only the early stages of differentiation is sufficient to block adipogenesis. In addition, we constructed a 3T3-L1 cell line harboring an inducible dominant negative p38 mutant. The induction of this dominant negative mutant of p38 prevents adipocyte differentiation. Thus, it is likely that the antiadipogenic activity of SB203580 and 8B202190 is indeed due to inhibition of p38 MAP kinase. This study points out that CCAAT/enhancer-binding protein β (C/EBPβ), a transcription factor critical for the initial stages of 3T3-L1 adipogenesis, bears a consensus site for p38 phosphorylation and serves as a substrate for p38 MAP kinase in vitro. Although the induction of C/EBPβ is not significantly altered in the presence of the p38 inhibitor, the amount of in vivo phosphorylated C/EBPβ is reduced by SB203580. The transcriptional induction of PPARγ, a gene whose expression is induced by C/EBPβ, and a factor critically involved in terminal differentiation of adipocytes, is impaired in the presence of p38 inhibitors. Thus, transcription factors such as C/EBPβ that promote adipocyte differentiation may be p38 targets during adipogenesis. Collectively, the data in this study suggest that p38 MAP kinase activity is important for proper 3T3-L1 differentiation.
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U2 - 10.1074/jbc.273.48.32111
DO - 10.1074/jbc.273.48.32111
M3 - Article
C2 - 9822687
AN - SCOPUS:0033610788
SN - 0021-9258
VL - 273
SP - 32111
EP - 32120
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 48
ER -