Rab4A GTPase-catenin interactions are involved in cell junction dynamics in the testis
Mruk,Dolores D.; Lau,Ann S.N.; Sarkar,Oli; Xia,Weiliang
Journal of Andrology 28(5): 742-754
Publication date: 2007
A plethora of evidence has recently accumulated to suggest thatRab guanosine triphosphates (GTPases) may have functions otherthan those originally proposed in vesicle formation, movement,docking, and fusion. Studies have shown, for example, thatRab proteins interact with actin filaments and microtubules,illustrating cross-talk between intracellular transport andcytoskeletal dynamics. In this report, we show that Rab4A associateswith adherens junction signaling proteins in the testis. Byimmunoprecipitation, Rab4A was found to interact with - andß-catenin as well as with actin, vimentin, - andß-tubulin, and protein kinase C (PKC)- and -. Additionally,administration of Adjudin to adult rats up-regulated the Rab4Alevel, which coincided with the loss of spermatocytes, roundand elongating/elongated spermatids from the seminiferous epithelium.More importantly, the ability of Rab4A to associate with -and ß-catenin increased during Adjudin-induced junctionrestructuring in the testis, illustrating that Rab4A-catenininteractions are likely to be involved in the disassembly ofSertoli-germ cell contacts. Taken collectively, theseresults suggest that Rab4A participates in adherens junctiondynamics.