title: The role of specific germ cell types in modulation of the secretion of androgen-regulated proteins (ARPs) by stage VI-VIII seminiferous tubules from the adult rat.
abstract: This study has assessed the role of specific germ cell types in modulating the secretion of seven previously identified androgen-regulated proteins (ARPs) as well as the increase in overall level of protein secretion by seminiferous tubules (ST) at stages VI-VIII of the spermatogenic cycle in the rat. Methoxyacetic acid (MAA) was administered at 650 mg/kg to induce 80-100% depletion of pachytene and later spermatocytes; ST at stages VI-VIII were then isolated at 4, 18 and 30 days after MAA treatment when pachytene spermatocytes (PS), round spermatids (RS) or elongate spermatids (ES), respectively, were depleted selectively. By comparison with ST isolated from controls or from rats 4 days after ethanedimethane sulphonate (EDS)-induced testosterone withdrawal, the overall level of incorporation of 35S-methionine into ST-secreted proteins was assessed after culture for 22 h at 32 degrees C as well as the relative abundance of ARPs identified by two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Depletion of PS caused a substantial decrease in abundance of ARP-6 (53-57 kDa; pI 5.7-5.8) and ARP-7 (56-59 kDa; pI 5.9-6.2) and minor and more variable decreases in ARP-3 (27-30 kDa; pI 7.4) and ARP-4 (38 kDa; pI 6.0-6.2); ARP-6 and ARP-7 are comparable in size to the A and B forms of P-Mod-S, a product of the peritubular cells. Depletion of RS resulted in the complete disappearance of ARP-2 (13-14.5 kDa; pI 7.3-7.6), a decrease in abundance of ARP-7 and variable decreases in ARP-1 (approximately 9.5 kDa; pI 6.9-7.4) and ARP-6; ARP-1 and -2 are thought to be Sertoli cell-secreted proteins. Depletion of ES had no effect on secretion of the ARPs. Depletion of PS, RS or ES resulted in significant (P less than 0.001) decreases of 26, 38 and 42% respectively in the overall level of incorporation of methionine into ST-secreted proteins, but this was significantly less than the decrease (55%) induced by EDS-induced testosterone withdrawal. These results show that the androgen-dependent changes in secretion of proteins, which occur specifically at stages VI-VIII of the normal spermatogenic cycle, are largely, if not completely, dependent on a normal germ cell complement, with each germ cell type regulating the secretion of proteins essential for its own development.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: MRC Reproductive Biology Unit, Centre for Reproductive Biology, Edinburgh, Scotland, UK.
authors.forename: C
authors.initials: C
authors.lastname: McKinnell
authors.forename: R M
authors.initials: RM
authors.lastname: Sharpe
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D046508:Culture Techniques; D015180:Electrophoresis, Gel, Two-Dimensional; D008297:Male; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012671:Seminiferous Tubules / Q000166:cytology / Q000378:metabolism*; D013087:Spermatids / Q000502:physiology*; D013090:Spermatocytes / Q000502:physiology*; D013091:Spermatogenesis; D013739:Testosterone / Q000502:physiology*
chemical_list: D000085:Acetates; D011506:Proteins; D013739:Testosterone; C013598:methoxyacetic acid