title: Involvement of the D-type cyclins in germ cell proliferation and differentiation in the mouse.
abstract: Using immunohistochemistry, the expression of the D-type cyclin proteins was studied in the developing and adult mouse testis. Both during testicular development and in adult testis, cyclin D(1) is expressed only in proliferating gonocytes and spermatogonia, indicating a role for cyclin D(1) in spermatogonial proliferation, in particular during the G(1)/S phase transition. Cyclin D(2) is first expressed at the start of spermatogenesis when gonocytes produce A(1) spermatogonia. In the adult testis, cyclin D(2) is expressed in spermatogonia around stage VIII of the seminiferous epithelium when A(al) spermatogonia differentiate into A(1) spermatogonia and also in spermatocytes and spermatids. To further elucidate the role of cyclin D(2) during spermatogenesis, cyclin D(2) expression was studied in vitamin A-deficient testis. Cyclin D(2) was not expressed in the undifferentiated A spermatogonia in vitamin A-deficient testis but was strongly induced in these cells after the induction of differentiation of most of these cells into A(1) spermatogonia by administration of retinoic acid. Overall, cyclin D(2) seems to play a role at the crucial differentiation step of undifferentiated spermatogonia into A(1) spermatogonia. Cyclin D(3) is expressed in both proliferating and quiescent gonocytes during testis development. Cyclin D(3) expression was found in terminally differentiated Sertoli cells, in Leydig cells, and in spermatogonia in adult testis. Hence, although cyclin D(3) may control G(1)/S transition in spermatogonia, it probably has a different role in Sertoli and Leydig cells. In conclusion, the three D-type cyclins are differentially expressed during spermatogenesis. In spermatogonia, cyclins D(1) and D(3) seem to be involved in cell cycle regulation, whereas cyclin D(2) likely has a role in spermatogonial differentiation.
authors.affiliation: Department of Cell Biology, University Medical Center Utrecht, 3584 CX, Utrecht, The Netherlands.
authors.forename: T L
authors.initials: TL
authors.lastname: Beumer
authors.forename: H L
authors.initials: HL
authors.lastname: Roepers-Gajadien
authors.forename: I S
authors.initials: IS
authors.lastname: Gademan
authors.forename: H B
authors.initials: HB
authors.lastname: Kal
authors.forename: D G
authors.initials: DG
authors.lastname: de Rooij
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D019938:Cyclin D1 / Q000502:physiology*; D056742:Cyclin D2; D056743:Cyclin D3; D016213:Cyclins / Q000502:physiology*; D005260:Female; D005854:Germ Cells / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011247:Pregnancy; D013737:Testis / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000378:metabolism / Q000473:pathology
chemical_list: C486196:Ccnd2 protein, mouse; C534697:Ccnd3 protein, mouse; D056742:Cyclin D2; D056743:Cyclin D3; D016213:Cyclins; D019938:Cyclin D1