Lack of acrosome formation in Hrb-deficient mice

N Kang-Decker, GT Mantchev, SC Juneja, MA McNiven… - Science, 2001 - science.org
N Kang-Decker, GT Mantchev, SC Juneja, MA McNiven, JMA van Deursen
Science, 2001science.org
The sperm acrosome is essential for sperm-egg fusion and is often defective in men with
nonobstructive infertility. Here we report that male mice with a null mutation in Hrb are
infertile and display round-headed spermatozoa that lack an acrosome. In wild-type
spermatids, Hrb is associated with the cytosolic surface of proacrosomic transport vesicles
that fuse to create a single large acrosomic vesicle at step 3 of spermiogenesis. Although
proacrosomic vesicles form in spermatids that lack Hrb, the vesicles are unable to fuse …
The sperm acrosome is essential for sperm-egg fusion and is often defective in men with nonobstructive infertility. Here we report that male mice with a null mutation in Hrb are infertile and display round-headed spermatozoa that lack an acrosome. In wild-type spermatids, Hrb is associated with the cytosolic surface of proacrosomic transport vesicles that fuse to create a single large acrosomic vesicle at step 3 of spermiogenesis. Although proacrosomic vesicles form in spermatids that lack Hrb, the vesicles are unable to fuse, blocking acrosome development at step 2. We conclude that Hrb is required for docking and/or fusion of proacrosomic vesicles during acrosome biogenesis.
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