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Spermiogenesis requires the transcription factor CREM (cyclic AMP-response element modulator)
in European Journal of EndocrinologyTranscriptional regulation by cyclic AMP (cAMP) of numerous eukaryotic genes is mediated through a consensus sequence present in the proximal part of their promoter (cis-elements) and termed cAMP-response element (CRE). Three transcription factors (transacting factors) that bind the CRE and are phosphorylated by protein kinase A (PKA) after activation of the cAMP signal transduction pathway have been identified: CRE binding protein (CREB), CRE modulator (CREM) and activating transcription factor 1 (ATF-1). They belong to the bZIP protein superfamily of transcription factors. Both CREB and ATF-1 are considered as transcriptional activators. The CREM gene generates numerous proteins by alternative splicing, promoter usage and translational initiation. Some of the products of the CREM gene are activators, while others are transcriptional repressors. A differential regulation of expression of the CREM gene has been observed in the testis during spermiogenesis. Premeiotic germ cells express the repressor isoforms of CREM at low level,
