Lack of Acrosome Formation in Hrb-Deficient Mice
Ningling Kang-Decker,1
George T. Mantchev,1
Subhash C. Juneja,1
Mark A. McNiven,23
Jan M. A. van Deursen1*
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.
1 Department of Pediatrics and Adolescent
Medicine,
2 Department of Biochemistry and Molecular
Biology,
3 Department of Gastroenterology and
Hepatology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
*
To whom correspondence should be addressed. E-mail:
vandeursen.jan{at}mayo.edu
