In cardiomyocyte hypoxia, insulin-like growth factor-I-induced antiapoptotic signaling requires phosphatidylinositol-3-OH-kinase-dependent and mitogen-activated protein kinase-dependent activation of the transcription factor cAMP response element-binding protein.

Journal Article (Journal Article)

BACKGROUND: A variety of pathologic stimuli lead to apoptosis of cardiomyocytes. Survival factors like insulin-like growth factor-I (IGF-I) exert anti-apoptotic effects in the heart. Yet the underlying signaling pathways are poorly understood. METHODS AND RESULTS: In a model of hypoxia-induced apoptosis of cultured neonatal cardiomyocytes, IGF-I prevented cell death in a dose-dependent manner. Antiapoptotic signals induced by IGF-I are mediated by more than one signaling pathway, because pharmacological inhibition of the phosphatidylinositol-3-OH-kinase (PI3K) or the mitogen-activated protein kinase kinase (MEK1) signaling pathway both antagonize the protective effect of IGF-I in an additive manner. IGF-I-stimulation was followed by a PI3K-dependent phosphorylation of AKT and BAD and an MEK1-dependent phosphorylation of extracellular signal-regulated kinase (ERK) 1 and ERK2. IGF-I also induced phosphorylation of cAMP response element-binding protein (CREB) in a PI3K- and MEK1-dependent manner. Ectopic overexpression of a dominant-negative mutant of CREB abolished the antiapoptotic effect of IGF-I. Protein levels of the antiapoptotic factor bcl-2 increased after longer periods of IGF-I-stimulation, which could be reversed by pharmacological inhibition of PI3K as well as MEK1 and also by overexpression of dominant-negative CREB. CONCLUSIONS: In summary, our data demonstrate that in cardiomyocytes, the antiapoptotic effect of IGF-I requires both PI3K- and MEK1-dependent pathways leading to the activation of the transcription factor CREB, which then induces the expression of the antiapoptotic factor bcl-2.

Full Text

Duke Authors

Cited Authors

  • Mehrhof, FB; Müller, FU; Bergmann, MW; Li, P; Wang, Y; Schmitz, W; Dietz, R; von Harsdorf, R

Published Date

  • October 23, 2001

Published In

Volume / Issue

  • 104 / 17

Start / End Page

  • 2088 - 2094

PubMed ID

  • 11673351

Electronic International Standard Serial Number (EISSN)

  • 1524-4539

Digital Object Identifier (DOI)

  • 10.1161/hc4201.097133

Language

  • eng

Conference Location

  • United States