Complementary expression and phosphorylation of Cx46 and Cx50 during development and following gene deletion in mouse and in normal and orchitic mink testes

Abstract

Gap junction-mediated communication helps synchronize interconnected Sertoli cell activities. Besides, coordination of germ cell and Sertoli cell activities depends on gap junction-mediated Sertoli cell-germ cell communication. This report assesses mechanisms underlying the regulation of connexin 46 (Cx46) and Cx50 in mouse testis and those accompanying a "natural" seasonal and a pathological arrest of spermatogenesis, resulting from autoimmune orchitis (AIO) in mink. Furthermore, the impact of deleting Cx46 or Cx50 on the expression, phosphorylation of junction proteins, and spermatogenesis is evaluated. Cx46 mRNA and protein expression increased, whereas Cx50 decreased with adulthood in normal mice and mink. Cx46 mRNA and protein expression increased, whereas Cx50 decreased with adulthood in normal mice and mink. During the mink active spermatogenic phase, Cx50 became phosphorylated and localized to the site of the blood-testis barrier. By contrast, Cx46 was dephosphorylated and associated with annular junctions, suggesting phosphorylation/dephosphorylation of Cx46 and Cx50 involvement in the barrier dynamics. Cx46-positive annular junctions in contact with lipid droplets were found. Cx46 and Cx50 expression and localization were altered in mink with AIO. The deletion of Cx46 or Cx50 impacted on other connexin expression and phosphorylation and differently affected tight and adhering junction protein expression. The level of apoptosis, determined by ELISA, and a number of Apostain-labeled spermatocytes and spermatids/tubules were higher in mice lacking Cx46 (Cx46-/-) than wild-type and Cx50-/- mice, arguing for life-sustaining Cx46 gap junction-mediated exchanges in late-stage germ cells secluded from the blood by the barrier. The data show that expression and phosphorylation of Cx46 and Cx50 are complementary in seminiferous tubules.

Glucose, insulin, insulin receptor subunits α and β in normal and spontaneously diabetic and obese ob/ob and db/db infertile mouse testis and hypophysis

“…Studies on development were carried out on the same male mice of BALB/cJ background that we used and described in our earlier study [15]. Five animals were used per age group.…”

“…These studies were carried out on the same mice as the ones we used and described in our earlier study [15]. Twenty male mice aged of 10 weeks with the leptin receptor (B6.BKS(D)-Leprdb/J homozygote (db/db) Stock Number 00697) mutation, 25 male mice aged of 10 weeks with the leptin (B6.Cg-Lepob/J homozygote (ob/ob) Stock Number 00632) mutation both experimental group on the C57BL/6 J genetic background and ten wild type (wt) mice were used to identify the consequences of diabetes and obesity resulting from distinct mutations of specific genes on selected testicular functions.…”

“…In humans, the serum leptin concentration is inversely proportional to androgen levels [14]. The db/db and ob/ob mice exhibit low testosterone levels [15]. The leptin's inhibiting action on food intake has been ascribed to fat stores and obesity [8].…”

Blood–testis barrier and Sertoli cell function: lessons from SCCx43KO mice

“…CX26, CX32, CX33, CX46, and CX50 (Brehm & Steger 2005, Pelletier et al 2015. Like all CX, CX43's name originates from its molecular weight of 43 kDa (Kumar & Gilula 1996).…”

Benzo[a]pyrene‐decreased gap junctional intercellular communication via calcium/calmodulin signaling increases apoptosis in TM4 cells

“…Several connexins (Cx26, 32, 33, 36, 45, 46 and 50) have been found to locate in specific compartments of the testis in various mammals, and are play different important roles in the testis and spermatogenesis (Kidder & Cyr, ). For example, Cx46 is not only very important for the survival of germ cells and the maintenance of the blood–testis barrier, but along with Cx50 it can regulate levels of Cx43 (Pelletier, Akpovi, Chen, Kumar, & Vitale, ). Cx43, the predominant constitutive proteins of gap junction in Sertoli cells, has been fully studied (Pointis & Segretain, ).…”