TY - JOUR
T1 - Loss of surface EWI-2 on CD9 null oocytes
AU - He, Zhi Yong
AU - Gupta, Surabhi
AU - Myles, Diana
AU - Primakoff, Paul
N1 - Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/7
Y1 - 2009/7
N2 - CD9, a member of the tetraspanin family, associates with a variety of other proteins to form the tetraspanin web. CD9 forms direct and relatively stable associations with the immunoglobulin superfamily proteins EWI-2 and EWI-F. Deletion of the Cd9 gene results in female infertility since Cd9 null mice produce oocytes that fail to fuse. It is thought that the absence of CD9 causes the inability of the oocytes to fuse. In this study, we report that the expression level of EWI-2 on the Cd9-/- oocyte surface is <10% of the wild-type level. Hence, the severe reduction in EWI-2 activity may be responsible for the loss of fusion ability. An entirely different mutant of CD9, not a deletion but a depalmitoylated construct, does not affect in vivo female fertility suggesting that the palmitate modification of CD9 is not essential for its putative fusion function. Additionally, the level of EWI-2 on the surface of the oocytes from these females was comparable to the EWI-2 level on wild-type oocytes. We also found that soluble, recombinant EWI-2 binds preferentially to acrosome-reacted sperm but the bound EWI-2 does not inhibit sperm-oocyte fusion. Overall, the results indicate that deletion of CD9, which is known to have multiple associations, may have pleiotropic effects on function that will require further dissection.
AB - CD9, a member of the tetraspanin family, associates with a variety of other proteins to form the tetraspanin web. CD9 forms direct and relatively stable associations with the immunoglobulin superfamily proteins EWI-2 and EWI-F. Deletion of the Cd9 gene results in female infertility since Cd9 null mice produce oocytes that fail to fuse. It is thought that the absence of CD9 causes the inability of the oocytes to fuse. In this study, we report that the expression level of EWI-2 on the Cd9-/- oocyte surface is <10% of the wild-type level. Hence, the severe reduction in EWI-2 activity may be responsible for the loss of fusion ability. An entirely different mutant of CD9, not a deletion but a depalmitoylated construct, does not affect in vivo female fertility suggesting that the palmitate modification of CD9 is not essential for its putative fusion function. Additionally, the level of EWI-2 on the surface of the oocytes from these females was comparable to the EWI-2 level on wild-type oocytes. We also found that soluble, recombinant EWI-2 binds preferentially to acrosome-reacted sperm but the bound EWI-2 does not inhibit sperm-oocyte fusion. Overall, the results indicate that deletion of CD9, which is known to have multiple associations, may have pleiotropic effects on function that will require further dissection.
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U2 - 10.1002/mrd.20991
DO - 10.1002/mrd.20991
M3 - Article
C2 - 19107828
AN - SCOPUS:67449097659
SN - 1040-452X
VL - 76
SP - 629
EP - 636
JO - Molecular Reproduction and Development
JF - Molecular Reproduction and Development
IS - 7
ER -