| Abstrakt: |
Few transcription factors in somatic cells of the testis and epididymis that could potentially regulate androgen-dependent developmental events during male gametogenesis have been identified. In this study we examined the regulation and expression of an orphan homeobox gene,Pem,which encodes a homeodomain related to those in thePrd/Paxgene family. RNase protection,in situhybridization, and Northern blot analyses of wild-type and germ-cell-deficient mutant mice (Wv/Wv) localized Pem transcripts to Sertoli cells of the testis. During prepubertal testicular development,Pemexpression was dramatically induced on Day 9, approximately when germ cells are known to enter meiotic prophase. In adult mice,Pemtranscripts were preferentially expressed in stages VII–VIII seminiferous epithelium, the androgen-dependent stages during which germ cells undergo the first step of meiosis.Pemgene expression depended on androgens and gonadotrophins, as demonstrated by a lack of expression in hypophysectomized mice, gonadotrophin-deficient hypogonadal (hpg) mutant mice, and androgen receptor-deficient (tfm) mutant mice. Injection of either testosterone or luteinizing hormone (LH) into hypophysectomized andhpg/hpgmice restoredPemexpression in the testes to normal levels. ThePemgene was also shown to be specifically expressed in the proximal cauda and distal corpus regions of the epididymis, the regions where spermatozoa gain forward motility and fertilization competence.Pemexpression in the epididymis did not depend on spermatozoa in the lumen of the testis, as shown in quaking (qk/qk) mutant mice, however, unlike in the testes, epididymalPemexpression required germ-cell-induced factors. Our results show that discrete cell types in male reproductive tissues transcribe and independently regulate thePemhomeobox gene. To our knowledge no transcription factors have previously been shown to depend on testosterone or LH for expression in Sertoli cellsin vivo.Collectively, the data implicatePemas a candidate to regulate a subset of androgen-dependent genes in the male reproductive system. |
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