| Co-Investigator(Kenkyū-buntansha) |
KASHIWABARA Shin-ichi KASHIWABARA,Shin-ichi, 応用生物化学系, 助教授 (00254318)
TAKAHASHI Satoru TAKAHASHI,Satoru, 基礎医学系, 教授 (50271896)
OKAMURA Naomichi OKAMURA,Naomichi, 基礎医学系, 教授 (30134224)
NISHIMURA Hitoshi NISHIMURA,Hitoshi, 応用生物化学系, 講師 (80241347)
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| Research Abstract |
To elucidate the functional regulation of mouse male gamete by other somatic cells and eggs, we have examined the cell interaction in spermatogenesis, sperm maturation, sperm transit from uterus to oviduct, and fertilization in mouse. The following experimental results have been obtained
(1)cDNA clones encoding a testis-specific poly(A) polymerase, TPAP, a candidate molecule responsible for cytoplasmic polyadenylation of pre-existing mRNAs in spermatogenic cells have been identified from a mouse testis cDNA library. Male mice lacking TPAP resulted in the arrest of spermatogenesis and in the increase of apoptosis in spermatogenic cells. The increased apoptosis before the stage of haploid round spermatids may be due not to direct effects of the spermatogenic arrest, but to a transduction of the spoptotic signals to the earlier stages of spermatogenic cells through Sertoli cells.
(2)In mouse, two different isoforms of ADAM1. ADAM1a and ADAM1b, are produced in the testis. ADAM1a is restricte
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dly localized within the endoplasmic reticulum of testicular germ cells, whereas epididymal sperm contain only ADAM1b on the plasma membrane. The loss of mouse ADAM1a resulted in the male infertility because of the severely impaired ability of sperm to migrate from the uterus into oviduct through the uterotubal junction. However, epididymal sperm of ADAM1a-deficient mice were capable of fertilizing the cumulus-intact, zona pellucida-intact eggs in vitro, despite the delayed dispersal of cumulus cells and the reduced adhesion/binding to the zona pellucida. These results suggest that the ADAM1a/ADAM2 fertilin complex may regulate the selective transport of specific sperm proteins including ADAM3, which are involved in the migration into the oviduct, in the dispersal of cumulus cells, and in the binding to the zona pellucida, from the endoplasmic reticulum of testicular germ cells onto the cell surface.
(3)Male mice lacking sperm PH-20 were still fertile, in spite of a reduced ability to disperse cumulus cells from the cumulus mass. Western blot analysis of sperm extracts revealed the presence of other hyaluronidase(s), except PH-20, presumably within the sperm acrosome. These data provide evidence that PH-20 is not essential for fertilization at least in the mouse, and suggest that the other hyaluronidase(s) may play an important role in the sperm penetration through the cumulus cell layer and/or the egg zona pellucida, possibly in cooperation with PH-20. Less
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