THE MUSCLE-SPECIFIC PHOSPHOGLYCERATE MUTASE GENE IS SPECIFICALLY EXPRESSED IN TESTIS DURING SPERMATOGENESIS

Spermatogenesis is a dramatic differentiation process which involves v ery selective but poorly characterized gene-expression patterns. To ga in insight into this process, we have investigated the expression duri ng spermatogenesis of the genes that encode phosphoglycerate mutase, a n essential glycolytic enzyme for the spermatozoa energy supply. By us ing cDNA and genomic probes we demonstrate the presence in testis of a mRNA corresponding to the muscle-specific phosphoglycerate mutase whi ch shows a longer poly(A) tail. This muscle-specific gene is submitted to developmental regulation during testis maturation and begins to be expressed at postnatal day 22, when germ cells start to enter into me iosis. Northern blot and in situ hybridization experiments show that i n contrast to what happens during skeletal-muscle differentiation, PGA M-M gene expression during spermatogenesis is not coupled to constitut ive phosphoglycerate mutase (PGAM-B) gene repression. Thus, the muscle -specific PGAM-M gene constitutes a meiotic gene and therefore represe nts a very interesting model to study differential tissue-specific gen e expression.