title: Insulin-like growth factor-II/cation-independent mannose 6-phosphate receptor mediates paracrine interactions during spermatogonial development.
abstract: The insulin-like growth factor-II/cation-independent mannose 6-phosphate (IGF-II/M6P) receptor transduces signals after binding IGF-II or M6P-bearing growth factors. We hypothesized that this receptor relays paracrine signals between Sertoli cells and spermatogonia in the basal compartment of the seminiferous epithelium. For these studies spermatogonia were isolated from 8-day-old mice with purity >95% and viability >85% after overnight culture. The IGF-II/M6P receptors were present on the surface of spermatogonia, as detected by indirect immunofluorescence. We determined that both IGF-II and M6P-glycoproteins in Sertoli cell conditioned medium (SCM) modulate gene expression in isolated spermatogonia. The IGF-II produced dose-dependent increases in both rRNA and c-fos mRNA. These effects were mediated specifically by IGF-II/M6P receptors, as shown by studies using IGF-II analogues that are specific agonists for either IGF-I or IGF-II receptors. The SCM treatment also induced dose-dependent increases in rRNA levels, and M6P competition showed that this response required interaction with IGF-II/M6P receptors. The M6P-glycoproteins isolated from SCM by IGF-II/M6P receptor affinity chromatography increased spermatogonial rRNA levels at much lower concentrations than required by SCM treatment, providing further evidence for the paracrine activity of Sertoli M6P-glycoproteins. These results demonstrate that Sertoli cells secrete paracrine factors that modulate spermatogonial gene expression after interacting with cell-surface IGF-II/M6P receptors.
authors.affiliation: The Laboratories for Reproductive Biology, Departments of Pediatrics and Cell Biology & Anatomy, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Tsuruta
authors.forename: E M
authors.initials: EM
authors.lastname: Eddy
authors.forename: D A
authors.initials: DA
authors.lastname: O'Brien
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016762:Genes, fos; D007335:Insulin-Like Growth Factor II / Q000031:analogs & derivatives / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008360:Mannosephosphates / Q000378:metabolism; D051379:Mice; D019899:Paracrine Communication; D012335:RNA, Ribosomal / Q000187:drug effects; D017527:Receptor, IGF Type 2 / Q000378:metabolism*; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D013093:Spermatogonia / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; D007476:Ionophores; D008360:Mannosephosphates; D012335:RNA, Ribosomal; D017527:Receptor, IGF Type 2; C027693:mannose-6-phosphate; D000001:Calcimycin; D007335:Insulin-Like Growth Factor II