CREM: A master-switch regulating the balance between differentiation and apoptosis in male germ cells

Cyclic AMP-responsive element modulator (CREM) is a transcription factor hi ghly expressed in the post-meiotic germ cells of the testis. its pivotal ro le is to regulate the expression of several germ cell-specific genes, a cru cial function as demonstrated by the severe phenotype of mice whose CREM ge ne was mutated by homologous recombination. CREM-deficient male animals are sterile and display a ten-fold increase in the apoptosis of germ cells. Re cent results have shown that CREM needs a tissue-specific co-activator, ACT (activator of CREM in testis) to elicit its regulatory function in testis. (C) 2000 Wiley-Liss, Inc.