title: Rictor/mTORC2 regulates blood-testis barrier dynamics via its effects on gap junction communications and actin filament network.
abstract: In the mammalian testis, coexisting tight junctions (TJs), basal ectoplasmic specializations, and gap junctions (GJs), together with desmosomes near the basement membrane, constitute the blood-testis barrier (BTB). The most notable feature of the BTB, however, is the extensive network of actin filament bundles, which makes it one of the tightest blood-tissue barriers. The BTB undergoes restructuring to facilitate the transit of preleptotene spermatocytes at stage VIII-IX of the epithelial cycle. Thus, the F-actin network at the BTB undergoes cyclic reorganization via a yet-to-be explored mechanism. Rictor, the key component of mTORC2 that is known to regulate actin cytoskeleton, was shown to express stage-specifically at the BTB in the seminiferous epithelium. Its expression was down-regulated at the BTB in stage VIII-IX tubules, coinciding with BTB restructuring at these stages. Using an in vivo model, a down-regulation of rictor at the BTB was also detected during adjudin-induced BTB disruption, illustrating rictor expression is positively correlated with the status of the BTB integrity. Indeed, the knockdown of rictor by RNAi was found to perturb the Sertoli cell TJ-barrier function in vitro and the BTB integrity in vivo. This loss of barrier function was accompanied by changes in F-actin organization at the Sertoli cell BTB in vitro and in vivo, associated with a loss of interaction between actin and α-catenin or ZO-1. Rictor knockdown by RNAi was also found to impede Sertoli cell-cell GJ communication, disrupting protein distribution (e.g., occludin, ZO-1) at the BTB, illustrating that rictor is a crucial BTB regulator.
authors.affiliation: Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065, USA.
authors.forename: Ka-Wai
authors.initials: KW
authors.lastname: Mok
authors.forename: Dolores D
authors.initials: DD
authors.lastname: Mruk
authors.forename: Will M
authors.initials: WM
authors.lastname: Lee
authors.forename: C Yan
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001814:Blood-Testis Barrier / Q000166:cytology / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006834:Hydrazines / Q000494:pharmacology; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D051381:Rats; D017207:Rats, Sprague-Dawley; D012670:Seminiferous Epithelium / Q000166:cytology / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D022502:Stress Fibers / Q000235:genetics / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C432482:1-(2,4-dichlorobenzyl)indazole-3-carbohydrazide; D000199:Actins; D002352:Carrier Proteins; D006834:Hydrazines; D007191:Indazoles; D046912:Multiprotein Complexes; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; C550254:rictor protein, rat; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases