Although Sertoli cell-expressed nectin-2 is linked to actin filaments of the apical ectoplasmic specializations, this cortical actin is non-contractile, and no myosin is associated with it. It therefore appears to have a merely structural function and is unlikely to act as a force-generating entity. Although a possible link between microtubule-based transport in Sertoli cells and translocation of the Sertoli-spermatid junctional plaque together with the attached spermatid has been suggested previously, the precise mechanisms of shaping and translocating the differentiating spermatid within the seminiferous epithelium are still elusive.
In this regard, it is noteworthy that we have recently identified an interaction between Tctex-1 and CD155, the closest known human relative of nectin-2. Interestingly, Tctex-1, a subunit of the dynein motor complex, is highly expressed in testis. The dynein complexes, in turn, have been found in association with apical junctional plaques. In the future, it will be interesting to determine whether a direct link between nectins and dynein exists. Albuterol Inhaler