THE MEF2B HOMOLOG DIFFERENTIALLY EXPRESSED IN MOUSE EMBRYONAL CARCINOMA-CELLS

The MEF2 gene family encodes a MADS-box transcription factor which reg ulates expression of many muscle-specific genes. We examined the expre ssion of the MEF2 genes in mouse embryonal carcinoma P19 cells before and after in vitro muscle differentiation induced by dimethyl sulfoxid e (DMSO). At least three different MADS/MEF2 domains (MEF2A, 2B and 2D ) were isolated from P19 cells with the MOPAC technique (mixed oligonu cleotides primed amplification of cDNA). Although two of the MADS/MEF2 domain sequences were identical to those of human MEF2A and MEF2D, an other domain sequence was similar but not identical to that of human M EF2B. While the transcription of MEF2A and MEF2D was up-regulated duri ng differentiation of P19 cells, the MEF2B homologue was abundantly tr anscribed in undifferentiated P19, F9 and ES cells and down-regulated in adult heart, skeletal muscle or brain, suggesting that the murine M EF2B homologue might have a function distinct from other members of th e MEF2 gene family in embryogenesis and development. (C) 1995 Academic Press, Inc.