Basement Membrane Laminin α2 Regulation of BTB Dynamics via Its Effects on F-Actin and Microtubule Cytoskeletons Is Mediated Through mTORC1 Signaling.
A local axis connects the apical ectoplasmic specialization (ES) at the Sertoli-spermatid interface, the basal ES at the blood-testis barrier (BTB), and the basement membrane across the seminiferous epithelium functionally in rat testes. As such, cellular events that take place simultaneously across the epithelium such as spermiation and BTB remodeling that occur at the apical ES and the basal ES, respectively, at stage VIII of the cycle are coordinated. Herein, laminin α2, a structural component of the basement membrane, was found to regulate BTB dynamics. Sertoli cells were cultured in vitro to allow the establishment of a tight junction (TJ) barrier that mimicked the BTB in vivo. Knockdown of laminin α2 by transfecting Sertoli cells with laminin α2-specific short hairpin RNA vs the nontargeting negative control was shown to perturb the Sertoli cell TJ barrier, illustrating laminin α2 was involved in regulating BTB dynamics. This regulatory effect was mediated through mammalian target of rapamycin complex 1 (mTORC1) signaling because the two mTORC1 downstream signaling molecules ribosomal protein S6 and Akt1/2 were activated and inactivated, respectively, consistent with earlier findings that mTORC1 is involved in promoting BTB remodeling. Also, laminin α2 knockdown induced F-actin and microtubule (MT) disorganization through changes in the spatial expression of F-actin regulators actin-related protein 3 and epidermal growth factor receptor pathway substrate 8 vs end-binding protein 1 (a MT plus-end tracking protein, +TIP). These laminin α2 knockdown-mediated effects on F-actin and MT organization was blocked by exposing Sertoli cells to rapamycin, an inhibitor of mTORC1 signaling, and also SC79, an activator of Akt. In summary, laminin α2-mediated regulation on Sertoli cell BTB dynamics is through mTORC1 signaling.
The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York.
Ying
Y
Gao
The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York.
Haiqi
H
Chen
School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
Wing-Yee
WY
Lui
School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
Will M
WM
Lee
The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York.
C Yan
CY
Cheng
D000085:Acetates / Q000494:pharmacology; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D001814:Blood-Testis Barrier / Q000187:drug effects / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism*; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
C000614067:AKT activator SC79; D000085:Acetates; D000199:Actins; D001578:Benzopyrans; D007797:Laminin; D046912:Multiprotein Complexes; D047428:Protein Kinase Inhibitors; C102645:laminin alpha 2; D000076222:Mechanistic Target of Rapamycin Complex 1; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus