TI - Sertoli-germ cell anchoring junction dynamics in the testis are regulated by an interplay of lipid and protein kinases . AB - When Sertoli and germ cells were co-cultured in vitro in chemically defined medium , functional anchoring junctions such as cell - cell intermediate filament -based desmosome-like junctions and cell - cell actin-based adherens junctions ( e.g. ectoplasmic specialization ( ES ) ) were formed within 1-2 days . This event was marked by the induction of several protein kinases such as phosphatidylinositol 3-kinase ( PI3K ) , phosphorylated protein kinase B ( PKB ; also known as Akt ) , p21-activated kinase-2 ( PAK-2 ) , and their downstream effector ( ERK ) as well as an increase in PKB intrinsic activity . PI3K , phospho (p) -PKB , and PAK were co-localized to the site of apical ES in the seminiferous epithelium of the rat testis in immunohistochemistry studies . Furthermore , PI3K also co-localized with p-PKB to the same site in the epithelium as determined by fluorescence microscopy , consistent with their localization at the ES . These kinases were shown to associate with ES-associated proteins such as beta1-integrin , phosphorylated focal adhesion kinase , and c-Src by co-immunoprecipitation , suggesting that the integrin.laminin protein complex at the apical ES likely utilizes these protein kinases as regulatory proteins to modulate Sertoli-germ cell adherens junction dynamics via the ERK signaling pathway . To validate this hypothesis further , an in vivo model using AF-2364 (1- ( 2,4-dichlorobenzyl ) -1H-indazole-3-carbohydrazide) to perturb Sertoli-germ cell anchoring junction function , inducing germ cell loss from the epithelium in adult rats , was used in conjunction with specific inhibitors . Interestingly , the event of germ cell loss induced by AF-2364 in vivo was also associated with induction of PI3K , p-PKB , PAK-2 , and p-ERK as well as a surge in intrinsic PKB activity . Perhaps the most important of all , pretreatment of rats with wortmannin ( a PI3K inhibitor ) or anti-beta1-integrin antibody via intratesticular injection indeed delayed AF-2364 -induced spermatid loss from the epithelium . In summary , these results illustrate that Sertoli-germ cell anchoring junction dynamics in the testis are regulated , atleast in part , via the beta1-integrin/PI3K/PKB/ERK signaling pathway .