Involvement of the D-Type Cyclins in Germ Cell Proliferation and Differentiation in the Mouse

• Published in: Biology of reproduction 2000-12, Vol.63 (6), p.1893-1898
• Main Authors: BEUMER, Tim L, ROEPERS-GAJADIEN, Hermien L, GADEMAN, Iris S, KAL, Henk B, DE ROOIJ, Dirk G
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cell Differentiation - physiology; Cell Division - physiology; Cyclin D1 - physiology; Cyclin D2; Cyclin D3; Cyclins - physiology; Female; Fundamental and applied biological sciences. Psychology; Germ Cells - physiology; Immunohistochemistry; Male; Mammalian male genital system; Medical sciences; Metabolic diseases; Mice; Mice, Inbred Strains; Morphology. Physiology; Other nutritional diseases (malnutrition, nutritional and vitamin deficiencies...); Pregnancy; Testis - cytology; Testis - growth & development; Testis - metabolism; Vertebrates: reproduction; Vitamin A Deficiency - metabolism; Vitamin A Deficiency - pathology
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod63.6.1893

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.