October 9 - 12, 2012
Building 10 & Natcher Conference Center
- General Schedule of Events
- Opening Plenary Session
- Concurrent Symposia Sessions
- Poster Sessions
- National Graduate Student Research Conference
- FARE Award Ceremony
- Special Exhibits on Resources for Intramural Research
- TSA Research Festival Exhibit Show
- Clinical Center Tours
- Research Festival Committees
- Past Research Festivals
Evolving paradigms in gamete recognition and induction of sperm acrosome exocytosis during mice and human fertilization
| Friday, November 08, 2013 — Poster Session IV | |||
|---|---|---|---|
2:00 p.m. – 4:00 p.m. |
FAES Academic Center (Upper-Level Terrace) |
NIDDK |
DEVBIO-2 |
Authors
- M.A. Avella
- B. Baibakov
- J. Dean
Abstract
The recent observation that human sperm bind to the mouse zona pellucida only when huZP2 replaces the endogenous mouse protein contradicts long-standing models of ZP3 acting as the primary mediator of gametes recognition and inducer of sperm acrosome exocytosis. We now establish loss-of-function assays in transgenic mice that express huZP4 to supplement the structural integrity of the zona matrix. We document that human and mouse sperm do not bind to a zona pellucida lacking huZP2 and moZP2, respectively, and female mice are sterile. Using chimeric human-mouse ZP2 proteins expressed in transgenic mice, we localize the sperm binding domain to the N-terminus. Sperm from transgenic mice in which nuclear protamines are tagged with EGFP and soluble mCherry is released upon acrosome exocytosis were imaged by time-lapse microscopy. Only acrosome-intact sperm bind to the surface of the zona pellucida and only acrosome-reacted sperm are present in the perivitelline space after penetration of the zona pellucida. Intriguingly, in the absence of ZP1, a looser zona matrix is formed to which acrosome-intact sperm bind and penetrate, but remain acrosome-intact. We conclude that the N-terminus of ZP2 is the ligand for gamete recognition and acrosome exocytosis is induced by the zona matrix during sperm penetration.
