|
|
|
|
|
|
|
||
* Department of Clinical Research, University of Berne, CH-3004 Berne, Switzerland; The molecular mechanisms regulating the
spectacular cytodifferentiation observed during spermiogenesis are poorly understood. We have recently identified a murine testis-specific serine kinase (tssk) 1, constituting a novel subfamily of serine/threonine kinases. Using low stringency screening we have isolated and
molecularly characterized a second closely related family member, tssk 2, which is probably the orthologue of
the human DGS-G gene. Expression of tssk 1 and tssk 2 was limited to the testis of sexually mature males. Immunohistochemical staining localized both kinases to the cytoplasm of late spermatids and to structures resembling residual bodies. tssk 1 and tssk 2 were absent
in released sperms in the lumen of the seminiferous tubules and the epididymis, demonstrating a tight window
of expression restricted to the last stages of spermatid
maturation. In vitro kinase assays of immunoprecipitates containing either tssk 1 or tssk 2 revealed no autophosphorylation of the kinases, however, they led to
serine phosphorylation of a coprecipitating protein of
~65 kD. A search for interacting proteins using the yeast
two-hybrid system with tssk 1 and tssk 2 cDNA as baits
and a prey cDNA library from mouse testis, led to the
isolation of a novel cDNA, interacting specifically with both tssk 1 and tssk 2, and encoding the coprecipitated
65-kD protein phosphorylated by both kinases. Interestingly, expression of the interacting clone was also
testis specific and paralleled the developmental expression observed for the kinases themselves. These results
represent the first demonstration of the involvement of
a distinct kinase family, the tssk serine/threonine kinases, together with a substrate in the cytodifferentiation of late spermatids to sperms.
Institute of Anatomy, CH-3012 Berne,
Switzerland; § Institute of Veterinary Parasitology, CH-3012 Berne, Switzerland; and Department of Urology, Inselspital,
CH-3010 Berne, Switzerland
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
