RAB13 participates in ectoplasmic specialization dynamics in the rat testis (PDF)
Mruk,Dolores D.; Lau,Ann S.N.
Biology of Reproduction 80(3): 590-601
Publication date: 2009
During spermatogenesis, leptotene spermatocytes residing inthe basal compartment of the seminiferous epithelium must traversethe blood-testis barrier (BTB) to gain entry into the adluminalcompartment for further development. At the same time, theseas well as other germ cell types in the epithelium must retaintheir close association with Sertoli cells via specialized celljunctions. In this study, we demonstrate that RAB13-aguanosine triphosphatase (GTPase) known to participate in tightjunction function in other epithelia-also participatesin the dynamics of the ectoplasmic specialization, a testis-specifictype of anchoring junction. By immunohistochemistry microscopy,RAB13 localized to the ectoplasmic specialization. Moreover,RAB13 was found to associate with vinculin (VCL) and espin (ESPN),two putative ectoplasmic specialization actin (ACT)-bindingproteins, by coimmunoprecipitation and immunofluorescence microscopyexperiments. To address the role of RAB13 in ectoplasmic specializationdynamics, an in vivo model was used in which administrationof Adjudin induced the disassembly of Sertoli-germ cell anchoringjunctions. Following administration of this drug, the RAB13level decreased steadily when the loss in testicular weightwas taken into account. Similarly, the association of RAB13with VCL decreased but was not completely lost during Adjudin-mediatedectoplasmic specialization restructuring. Taken collectively,these results suggest that RAB13 functions in ectoplasmic specializationdynamics in the testis.
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