Talk:Fertilization

2010

The role and regulation of sperm gelsolin prior to fertilization

J Biol Chem. 2010 Oct 11.

Finkelstein M, Etkovitz N, Breitbart H.

Bar-Ilan University, Israel. Abstract In order to acquire fertilization competence, spermatozoa should undergo several biochemical changes in the female reproductive tract, known as capacitation. The capacitated spermatozoon can interact with the egg zona-pellucida resulting in the occurrence of the acrosome reaction, a process which allowed its penetration into the egg and fertilize it. Sperm capacitation requires actin polymerization, while F-actin must disperse prior to the acrosome reaction. Here we suggest that the actin severing protein, gelsolin, is inactive during capacitation and is activated prior to the acrosome reaction. The release of bound gelsolin from phosphatidylinositol 4,5-bisphosphate (PIP(2)) by PBP10, a peptide containing the PIP2-binding domain of gelsolin, or by activation of PLC which hydrolyses PIP(2), caused rapid Ca(2+)-dependent F-actin depolymerization as well as enhanced acrosome reaction. Using immunoprecipitation assays, we showed that the tyrosine kinase SRC and gelsolin coimmunoprecipitate, and activating SRC by adding 8Br-cAMP enhanced the amount of gelsolin in this precipitate. Moreover, 8Br-cAMP enhanced tyrosine phosphorylation of gelsolin and its binding to PIP(2(4,5)), both of which inactivated gelsolin, allowing actin polymerization during capacitation. This actin polymerization was blocked by inhibiting the Src-family-kinases, suggesting that gelsolin is activated under these conditions. These results are further supported by our finding that PBP10 was unable to cause complete F-actin breakdown in the presence of 8Br-cAMP or vanadate. In conclusion, inactivation of gelsolin during capacitation occurs by its binding to PIP(2) and tyrosine phosphorylation by SRC. The release of gelsolin from PIP(2) together with its dephosphorylation enables gelsolin activation, resulting in the acrosome reaction.

PMID: 20937821 http://www.ncbi.nlm.nih.gov/pubmed/20937821

Sperm head binding to epithelium of the oviduct isthmus is not an essential preliminary to mammalian fertilization - review

Zygote. 2010 Jul 21:1-5.

Hunter RH.

Institute for Reproductive Medicine, Hannover Veterinary University, Bünteweg 15, D-30559 Hannover, Germany. Abstract SummaryIn endeavouring to understand the nature of sperm-oviduct interactions in mammals, attention was focused on experimental models in which fertilization can occur without a preliminary phase of sperm head binding to the isthmus epithelium. The ovarian endocrine milieu imposed on the oviduct tissues plays an important role in the binding phenomenon, although less so after the time of ovulation. Nonetheless, a sperm suspension introduced into the peritoneal cavity or surgical insemination directly into the oviduct ampulla before ovulation can result in fertilization, as can a surgical model in which the isthmus has been resected and the remaining portions of the duct reanastomosed. Mating or artificial insemination after ovulation in pigs permits rapid sperm transport to the site of fertilization, and the frequency of polyspermic penetration increases with the post-ovulatory age of eggs.Strategies underlying sperm binding were considered, especially in terms of preovulatory sperm storage and suppression of full membranous maturation. These, in turn, raised the problem of how sperm binding in vitro to oviduct cells from prepuberal animals or to cells harvested during the luteal phase of the estrous cycle, or to cells from the ampulla or even the tracheal epithelium, can act to regulate sperm storage and maturation with precision. In an evolutionary perspective, preovulatory binding of diverse populations of cells to the endosalpinx may have developed as a form of fine tuning to assist in sperm selection, to synchronize completion of capacitation with the events of ovulation, and to promote monospermic fertilization by a controlled release of competent gametes.

PMID: 20663263 http://www.ncbi.nlm.nih.gov/pubmed/20663263

2009

Etiology of sperm immunity in women

Fertil Steril. 2009 Feb;91(2):639-43. Epub 2008 Feb 20.

Clarke GN.

Andrology Unit, Royal Women's Hospital, Melbourne, Victoria, Australia. gary.clarke@rch.org.au

Abstract Sperm immunity in females can reduce the likelihood of natural conception, and sperm antibodies from female sera have been shown to inhibit IVF in humans and in several animal models. The etiology of sperm immunity in human females is unknown, but several possible mechanisms have been proposed, including cross-reactivity with microbial antigens and interferon gamma-mediated potentiation of the antisperm immune response in women whose male partners have sperm autoantibodies in their semen. This article reviews these ideas and postulates a novel hypothesis based on the potential for the generation of anti-idiotype antibodies in women whose partners have sperm antibodies in their semen.

PMID: 18281044

http://www.ncbi.nlm.nih.gov/pubmed/18281044

Egg coat proteins activate calcium entry into mouse sperm via CATSPER channels

Xia J, Ren D. Biol Reprod. 2009 Jun;80(6):1092-8. Epub 2009 Feb 11. PMID: 19211808

2008

IJDB

Vol. 52 Nos. 5/6 (2008) Fertilization

http://www.ijdb.ehu.es/web/contents.php?vol=52&issue=5-6

Sperm binding to the zona pellucida is not sufficient to induce acrosome exocytosis.

Baibakov B, Gauthier L, Talbot P, Rankin TL, Dean J. Development. 2007 Mar;134(5):933-43. PMID: 17293534

ZP2 and ZP3 traffic independently within oocytes prior to assembly into the extracellular zona pellucida

Hoodbhoy T, Avilés M, Baibakov B, Epifano O, Jiménez-Movilla M, Gauthier L, Dean J. Mol Cell Biol. 2006 Nov;26(21):7991-8. PMID: 17047254

inactive X chromosome

Cell cycle-dependent localization of macroH2A in chromatin of the inactive X chromosome. Chadwick BP, Willard HF. J Cell Biol. 2002 Jun 24;157(7):1113-23. Epub 2002 Jun 24. PMID: 12082075 \ JCB

Histone modifications and nuclear architecture: a review.

Bártová E, Krejcí J, Harnicarová A, Galiová G, Kozubek S.

J Histochem Cytochem. 2008 Aug;56(8):711-21. Epub 2008 May 12. Review.PMID: 18474937