title: Ca(2+)/calmodulin-dependent protein kinase IV is expressed in spermatids and targeted to chromatin and the nuclear matrix.
abstract: Ca(2+)/calmodulin-dependent protein kinase IV and calspermin are two proteins encoded by the Camk4 gene. Both are highly expressed in the testis, where in situ hybridization studies in rat testes have demonstrated that CaMKIV mRNA is localized to pachytene spermatocytes, while calspermin mRNA is restricted to spermatids. We have examined the expression patterns of both CaMKIV and calspermin in mouse testis and unexpectedly find that CaMKIV is expressed in spermatogonia and spermatids but excluded from spermatocytes, while calspermin is found only in spermatids. CaMKIV and calspermin expression in the testis are stage-dependent and appear to be coordinately regulated. In germ cells, we find that CaMKIV is associated with the chromatin. We further demonstrate that a fraction of CaMKIV in spermatids is hyperphosphorylated and specifically localized to the nuclear matrix. These novel findings may implicate CaMKIV in chromatin remodeling during nuclear condensation of spermatids.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: J Y
authors.initials: JY
authors.lastname: Wu
authors.forename: A R
authors.initials: AR
authors.lastname: Means
mesh_terms: D000818:Animals; D015153:Blotting, Western; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000302:isolation & purification*; D002148:Calmodulin-Binding Proteins / Q000302:isolation & purification; D002451:Cell Compartmentation; D002843:Chromatin / Q000201:enzymology*; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D015530:Nuclear Matrix / Q000201:enzymology*; D010766:Phosphorylation; D013045:Species Specificity; D013087:Spermatids / Q000201:enzymology*; D013737:Testis / Q000033:anatomy & histology / Q000201:enzymology; D014018:Tissue Distribution
chemical_list: D002148:Calmodulin-Binding Proteins; D002843:Chromatin; C051666:calspermin; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517685:Camk4 protein, mouse; C517686:Camk4 protein, rat