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Deficiency in the Omega-3 Fatty Acid Pathway Results in Failure of Acrosome Biogenesis in Mice.
MedLine Citation:
PMID:  21653892     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
An omega-3 fatty acid, docosahexaenoic acid (DHA) is enriched in testicular membrane phospholipids, but its function is not well understood. The Fads2 gene encodes an enzyme required for the endogenous synthesis of DHA. Using Fads2-null mice (Fads2-/-), we found in our preceding studies that DHA deficiency caused the arrest of spermiogenesis and male infertility, both of which were reversed by dietary DHA. In this study, we investigated a cellular mechanism underlying the DHA essentiality in spermiogenesis. Periodic-acid-Schiff staining and acrosin immunohistochemistry revealed the absence of acrosomes in Fads2-/- round spermatids. Acrosin, an acrosomal marker, was scattered throughout the cytoplasm of the Fads2-/- spermatids, and electron microscopy showed that proacrosomal granules were formed on the trans-face of the Golgi. However, excessive endoplasmic reticulum and vesicles were present on the cis-face of the Golgi in Fads2-/- spermatids. The presence of proacrosomal vesicles but lack of a developed acrosome in Fads2-/- spermatids suggested failed vesicle fusion. Syntaxin 2, a protein involved in vesicle fusion, colocalized with acrosin in the acrosome of wild-type mice. In contrast, syntaxin 2 remained scattered in reticular structures and showed no extensive colocalization with acrosin in the Fads2-/- spermatids, suggesting failed fusion with acrosin-containing vesicles or failed transport and release of syntaxin 2 vesicles from Golgi. Dietary supplementation of DHA in Fads2-/- mice restored an intact acrosome. In conclusion, acrosome biogenesis under DHA deficiency is halted after release of proacrosomal granules. Misplaced syntaxin2 suggests an essential role of DHA in proper delivery of membrane proteins required for proacrosomal vesicle fusion.
Authors:
Manuel Roqueta-Rivera; Timothy L Abbott; Mayandi Sivaguru; Rex A Hess; Manabu T Nakamura
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-8
Journal Detail:
Title:  Biology of reproduction     Volume:  -     ISSN:  1529-7268     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-6-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0207224     Medline TA:  Biol Reprod     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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