CHARACTERIZATION AND DEVELOPMENTAL EXPRESSION OF A TESTIS-SPECIFIC ADENOSINE-DEAMINASE MESSENGER-RNA IN THE MOUSE

Adenosine is able to alter intracellular cAMP levels and to affect the physiological functions of sperm. It also modulates FSH action throug h its Gi protein coupled receptors. Adenosine deaminase (ADA), an enzy me regulating adenosine levels, exists in the plasma membrane of the s perm, but little is known about its action on testicular function. The present study investigates the expression of a testis-specific ADA mR NA with development and in comparison to several other tissues in the mouse. In addition, the sequence of a testis-specific ADA cDNA was det ermined from an adult mouse testis library. We demonstrate for the fir st time the presence of a major 1,350 bp testis-specific ADA mRNA and a weaker 1,200 bp ADA transcript whose developmental expression starts on day 28 of life. Sequence analysis of the testis-specific ADA cDNA indicated that exons 1 and 2, as well as the first 8 nucleotides of ex on 3 of the somatic cell ADA cDNA, were absent in the testicular ADA c DNA. The deduced open reading frame of the testis-specific ADA cDNA in dicates absence of the first 51 amino acids at the 5' end that are pre sent in the somatic cell ADA protein. The developmental onset of expre ssion of the testis-specific ADA mRNA may be related to specific proli feration/differentiation events of spermatogenesis.