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Mol Endocrinol. 2001 Nov;15(11):2037-49.

Activation of extracellular signal-regulated kinases and CREB/ATF-1 mediate the expression of CCAAT/enhancer binding proteins beta and -delta in preadipocytes.

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1
Institute of Signaling, Development Biology and Cancer Research, UMR 6543 Centre Nationale de la Recherche Scientifique, Centre de Biochimie 06108 Nice Cedex 2, France.

Abstract

The essential role of CCAAT/enhancer binding proteins (C/EBPs) beta and delta for adipocyte differentiation has been clearly established. In preadipocytes, their expression is up-regulated by the activation of leukemia inhibitory factor receptor (LIF-R) and prostacyclin receptor (IP-R) via the extracellular signal-regulated kinase (ERK) pathway and cAMP production, respectively. However, the molecular mechanisms by which LIF and prostacyclin-induced signals are propagated to the nucleus and the transcription factors mediating ERK and cAMP-induced C/EBP gene expression were unknown. Here we report that both pathways share cAMP responsive element binding protein/activation transcription factor 1 (CREB/ATF-1) as common downstream effectors. LIF-R and IP-R activation induced binding of CREB and/or ATF-1 to C/EBP promoters and CREB-dependent transcription. Expression of dominant negative forms of CREB dramatically reduced the LIF- and prostacyclin-stimulated C/EBP beta and C/EBP delta expression. Upon stimulation of the IP-R, the ERK pathway was activated in a PKA-dependent manner. ERK activation by the PKA pathway was not required for CREB/ATF-1 phosphorylation but rather was necessary for CREB-dependent up-regulation of C/EBPs expression. Our findings suggest that ERK activation is required for CREB transcriptional activity, possibly by recruitment of a coactivator.

PMID:
11682632
DOI:
10.1210/mend.15.11.0721
[Indexed for MEDLINE]

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