Institute of Development, Aging and Cancer, Tohoku University


Seminars and Symposia

IDAC Seminar, 12 June 2015

Secretariat, Alumni Association, IDAC
Date Friday,12 June 2015, 16:00~
Room Seminar-shitsu 1, IDAC Research building 7F
Title Retinoic acid cyclically induces germ cell differentiation and meiosis during spermatogenesis
Speaker Tsutomu Endo, Ph.D.
Affiliation Whitehead Institute for Biomedical Research
Person-in-charge Kentaro Mochizukii Cell Resource Center for Biomedical Research (ext. 8572)
Abstract Mouse spermatogenesis is complex and highly coordinated process in which spermatogonia differentiate and spermatocytes initiate meiosis at the same time, every 8.6 days, resulting in the spatiotemporal associations of germ cells (1). Both spermatogonial differentiation and meiotic initiation require an extrinsic signal, retinoic acid (RA). We has found that Stra8, an RA-responsive gene expressed in germ cells, regulate these two events (2, 3, 4).
Here, using mice in vivo, we show that the timing of two events is determined by local RA levels in testes and the intrinsic competence of germ cells to express STRA8. We conclude that a very simple regulatory mechanism, cyclical RA-STRA8 signaling with germ cell competence, is sufficient for the cycle of spermatogenesis. The complex organization of spermatogenesis such as cell-cell associations, which has been thought to be rigid since 1956 (1), is a flexible by-product and dispensable for germ cell development.

(1) Oakberg (1956) Am. J. Anat., 99(3):507-516.
(2) Baltus et al. (2006) Nat. Genet., 38(12):1430-1434.
(3) Anderson et al. (2008) PNAS, 105(39):14976-14980.
(4) Endo et al., (2015) PNAS, in press.