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Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos
Published on: June 6, 2016
Normal fertilization occurs with eggs lacking the integrin alpha6beta1 and is CD9-dependent.
B J Miller1, E Georges-Labouesse, P Primakoff
1Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616, USA.
The Journal of Cell Biology
|June 13, 2000
Summary
The alpha6beta1 integrin is not essential for mouse sperm-egg fusion. Instead, the tetraspanin CD9 plays a crucial role, potentially acting independently or with other proteins in this process.
Area of Science:
- Reproductive Biology
- Cellular Biology
- Molecular Biology
Background:
- Previous studies suggested alpha6beta1 integrin on mouse eggs acts as the sperm receptor.
- Egg surface tetraspanin CD9 is essential for gamete fusion and known to associate with integrins.
- Models proposed CD9 functions with alpha6beta1 integrin in sperm-egg fusion.
Purpose of the Study:
- To investigate the role of alpha6beta1 integrin in mouse sperm-egg fusion.
- To re-evaluate the necessity of alpha6beta1 integrin and the function of CD9 in gamete fusion.
Main Methods:
- Utilized eggs from cultured ovaries of mice genetically deficient in the alpha6 integrin subunit.
- Assessed fertilization rate, fertilization index, and sperm binding in alpha6 integrin-deficient eggs compared to controls.
- Re-examined antibody inhibition of fertilization using an assay simulating in vivo conditions.
- Tested the effect of anti-CD9 monoclonal antibody (mAb) on sperm fusion with wild-type and alpha6beta1-deficient eggs.
Main Results:
- Fertilization rate, fertilization index, and sperm binding were not impaired in eggs lacking alpha6 integrin.
- Re-evaluation showed no inhibition of sperm-egg fusion by the anti-alpha6 integrin mAb (GoH3) under simulated in vivo conditions.
- An anti-CD9 mAb completely blocked sperm fusion with both wild-type eggs and eggs lacking alpha6beta1.
Conclusions:
- The alpha6beta1 integrin is not essential for mouse sperm-egg fusion.
- CD9 is critical for sperm-egg fusion and may function independently or with other egg proteins besides alpha6beta1.
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