COORDINATE EXPRESSION OF THE PRM1, PRM2, AND TNP2 MULTIGENE LOCUS IN HUMAN TESTIS

Maintenance of the transcriptionally inert state of the mature human s permatozoon requires the expression of the various members of the huma n protamine gene cluster prior to the final stages of spermatogenesis. During this process, known as spermiogenesis, round spermatids morpho logically differentiate into mature spermatozoa. The expression of the PRM1, PRM2, and TNP2 genes facilitates the compaction and condensatio n of the genetic material within the developing spermatid. To understa nd better the coordinate control governing this transformation, we hav e examined the localization and distribution of the human protamines P RM1 and PRM2 and transition protein TNP2 transcripts during human sper matogenesis. The stage-specific expression of these transcripts was de termined by in situ hybridization analysis using [alpha-S-35]-labeled cRNA probes, PRM1, PRM2, and TNP2 transcripts were abundant in associa tion with round and elongating spermatids, located in the adluminal re gion of the seminiferous epithelium. They were not observed in associa tion with spermatogonia, spermatocytes, Sertoli cells, or interstitial cells. These data indicate that the human PRM1, PRM2, and TNP2 transc ripts are expressed postmeiotically in round and elongating spermatids . The quantitative evaluation of each transcript was determined as a f unction of the relative optical density per unit area. In all cases ex amined, the relative level of each transcript was consistent with the following pattern, PRM2 > PRM1 similar or equal to TNP2.