DEOXYRIBONUCLEIC-ACID PROTEIN INTERACTIONS AND EXPRESSION OF THE HUMAN TESTIS-SPECIFIC LACTATE-DEHYDROGENASE PROMOTER - TRANSCRIPTION FACTOR SP1 PLAYS A MAJOR ROLE

The human testis-specific lactate dehydrogenase c gene (Idh-C) shows a n exceptionally large window of expression throughout pre-and postmeio tic stages of the male germ cell lineage, In order to characterize the multiple stage-specific transcription factors necessary for Idh-c exp ression, we previously characterized the human Idh-c core promoter, He re, we used a combination of gel retardation assays and an in vitro tr anscription system derived from human tissues to better define the ele ments that govern Idh-c transcription, Three classes of transcriptiona l regulators were defined by these experiments, 1) The Spl transcripti on factor is a testis-''enriched'' protein that is absent from most so matic tissues and that appears to play a major role in determining Idh -c expression in the testis, Highest levels of Sp1 during spermatogene sis correlate with maxima of Idh-c expression, 2) The testis-specific cAMP response element modulator (CREMt) transcription factor binds a c AMP response element (CRE)-like sequence located at position -433, Thi s transcriptional activator might contribute to postmeiotic transcript ion of Idh-c, 3) Factors present in tissues negative for Idh-c express ion appear to bind both the CRE-like sequence and an adjacent hormone response element, The presence of this element could be involved in re gulating Idh-c through the glucocorticoid/androgen pathways at the ear ly stages of Idh-c expression.