Developmental distribution of the polyadenylation protein CstF-64 and the variant tauCstF-64 in mouse and rat testis

Messenger RNA polyadenylation is one of the processes that control gene expression in all eukaryotic cells and tissues. In mice, there are two forms of the regulatory polyadenylation protein, CstF-64. The gene Cstf2 on the X chromosome encodes this form, and it is expressed in all somatic tissues. The second form, τCstF-64 (encoded by the autosomal gene Cstf2t), is expressed in a more limited set of tissues and cell types, largely in meiotic and postmeiotic male germ cells, and to a smaller extent in brain. We report here that, while CstF-64 and τCstF-64 expression in rat tissues resembles their expression in mouse tissues, there are also significant differences. First, unlike in mice where CstF-64 was expressed in postmeiotic round and elongating spermatids, rat CstF-64 was absent in those cell types. Second, unlike in mice, τCstF-64 was expressed at significant levels in rat liver. These differences in expression suggest interesting differences in X chromosomal gene expression between these two rodent species.