F5-Peptide and mTORC1/rpS6 Effectively Enhance BTB Transport Function in the Testis - Lesson from the Adjudin Model

Baiping Mao, Linxi Li, Ming Yan, Chris K C Wong, Bruno Silvestrini, Chao Li, Renshan Ge, Qingquan Lian, C. Yan Cheng*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

15 Citations (Scopus)


During spermatogenesis, the blood-testis barrier (BTB) undergoes cyclic remodeling that is crucial to support the transport of preleptotene spermatocytes across the immunological barrier at stage VIII to IX of the epithelial cycle. Studies have shown that this timely remodeling of the BTB is supported by several endogenously produced barrier modifiers across the seminiferous epithelium, which include the F5-peptide and the ribosomal protein S6 [rpS6; a downstream signaling molecule of the mammalian target of rapamycin complex 1 (mTORC1)] signaling protein. Herein, F5-peptide and a quadruple phosphomimetic (and constitutively active) mutant of rpS6 [i.e., phosphorylated (p-)rpS6-MT] that are capable of inducing reversible immunological barrier remodeling, by making the barrier "leaky" transiently, were used for their overexpression in the testis to induce BTB opening. We sought to examine whether this facilitated the crossing of the nonhormonal male contraceptive adjudin at the BTB when administered by oral gavage, thereby effectively improving its BTB transport to induce germ cell adhesion and aspermatogenesis. Indeed, it was shown that combined overexpression of F5-peptide and p-rpS6-MT and a low dose of adjudin, which by itself had no noticeable effects on spermatogenesis, was capable of perturbing the organization of actin- and microtubule (MT)-based cytoskeletons through changes in the spatial expression of actin- and MT-binding/regulatory proteins to the corresponding cytoskeleton. These findings thus illustrate the possibility of delivering drugs to any target organ behind a blood-tissue barrier by modifying the tight junction permeability barrier using endogenously produced barrier modifiers based on findings from this adjudin animal model.

Original languageEnglish
Article number201900308
Pages (from-to)1832-1853
Number of pages22
Issue number8
Publication statusPublished - 4 Jul 2019

Scopus Subject Areas

  • Endocrinology


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