8 - Control of Cardiac Development by the MEF2 Family of Transcription Factors

Abstract

Recent studies in fruit flies and mice have demonstrated that members of the myocyte enhancer factor-2 (MEF2) family of transcription factors play multiple roles in cardiac myogenesis and morphogenesis. This chapter discusses the multiple functions of MEF2 factors in heart development and speculates about the potential mechanisms whereby these transcription factors control different sets of target genes at multiple steps in the cardiogenic pathway. It is found that diversity of MEF2 proteins in vertebrates is likely to account for the numerous potential roles played by MEF2 factors in the differentiation of muscle, heart, and neural lineages. In addition to the role of MEF2 factors in tissue-specific differentiation, certain splice variants of MEF2 may be important in cell proliferation. Recently, a ubiquitous isoform of MEF2D was shown to regulate the serum inducibility of the c-jun promoter. Likewise, MEF2 protein expression was shown to be up regulated upon proliferation of vascular smooth muscle cells following balloon injury. Thus, the presence of four reef2 genes with numerous splice variants and the possibility of heterodimerization among MEF2 factors creates multiple different mef2 products with numerous potential roles in the transcriptional control of genes important in a variety of cellular processes.