Expression of Fer testis (FerT) tyrosine kinase transcript variants and distribution sites of FerT during the development of the acrosome-acroplaxome-manchette complex in rat spermatids.

We report the association of testicular Fer, a non-receptor tyrosine kinase, with acrosome development and remodeling of the acrosome-associated acroplaxome plate during spermatid head shaping. A single gene expresses two forms of Fer tyrosine kinases in testis: a somatic form (FerS) and a truncated testis-type form (FerT). FerT transcript variants are seen in spermatocytes and spermatids. FerS transcripts are not detected in round spermatids but are moderately transcribed in spermatocytes. FerT protein is associated with the spermatid medial/trans-Golgi region, proacrosomal vesicles, the cytosolic side of the outer acrosome membrane and adjacent to the inner acrosome membrane facing the acroplaxome. FerT coexist in the acroplaxome with phosphorylated cortactin, a regulator of F-actin dynamics. We propose that FerT participates in acrosome development and that phosphorylated cortactin may contribute to structural changes in F-actin in the acroplaxome during spermatid head shaping. (c) 2008 Wiley-Liss, Inc.