Cx30.2 deletion causes imbalances in testicular Cx43, Cx46, and Cx50 and insulin receptors. Reciprocally, diabetes/obesity alters Cx30.2 in mouse testis

Abstract

Cx30.2 protein content and localization were assessed during development. An account of Cx30.2, Cx43, Cx46, and Cx50, and insulin receptor (IR) responses to Cx30.2, Cx46, or Cx50 deficiency in mouse interstitial tissue (ITf)- and seminiferous tubule-enriched fractions (STf) is given. The impact of high glucose/insulin on Cx30.2 was investigated in spontaneously diabetic and obese db/db and ob/ob mouse testis and anterior pituitary (AP). Cx30.2 labeled contacts in vascular endothelial and Leydig cells and Sertoli cell junctions in stage V–VII. Cx30.2 expression is regulated differently in the interstitium and tubules. Cx30.2 at 30-kDa levels peaked by 28 days in ITf and by 14 days in STf. In STf, deleting Cx30.2 decreased Cx43 and Cx50, whereas deleting Cx50 downregulated Cx30.2. The opposite occurred in ITf. In STf, deleting Cx30.2 upregulated Cx46 except the full-length reciprocally, deleting Cx46 upregulated Cx30.2. In ITf, Cx30.2 deficiency upregulated full-length and phosphorylated Cx46, whereas deleting Cx46 downregulated 48- to 50-kDa Cx30.2. The db/db and ob/ob mouse ITf, STf, and AP showed imbalanced Cx30.2 levels. IRα levels at 135 kDa declined in Cx30.2−/− and Cx50−/− mouse ITf and Cx46−/− and Cx50−/− STf. IRβ at 98 to 110 kDa dropped in Cx30.2−/− and Cx46−/− mice STf suggesting that Cx30.2 deficiency decreases active IR sites. The results show the connexins interdependence and interaction and that altering a single connexin changes the remaining connexins expression, which can modify gap junction-mediated glucose exchanges in contacting cells. Data suggest that glucose/insulin influences Cx30.2 turnover in testis and AP and, reciprocally, that connexins modulate testis glucose uptake and response to insulin.

PCSK9 Contributes to the Cholesterol, Glucose, and Insulin2 Homeostasis in Seminiferous Tubules and Maintenance of Immunotolerance in Testis

“…The mouse interstitial tissue contains both insulinT and insulin2 whereas tubules contain chiefly insulin 2 ( Pelletier et al, 2020a ). The drop in glucose in presence of elevated insulin2 concentrations evidences a normal response to insulin in tubules in contrast to the interstitial tissue-fractions in which the elevated insulin2 levels were not accompanied by a decrease in glucose in Pcsk9 −/− mice.…”

“…Studies on postnatal development were carried out on the same 7- to >60-day-old male mice or >60 days adult of BALB/cJ background that we used and described earlier ( Pelletier et al, 2015 ; Pelletier et al, 2018 ; Pelletier et al, 2020a ; Pelletier et al, 2020b ). Three animals were used per age group.…”

“…To identify the consequences of diabetes and obesity on PCSK9 protein expression we used the same spontaneously diabetic and obese ob/ob and db/db as the ones we used and described in our earlier studies ( Pelletier et al, 2018 ; Pelletier et al, 2020a ; Pelletier et al, 2020b ). Ten male mice aged of 10 weeks with the leptin receptor (B6.BKS(D)- Leprdb /J homozygotes ( db / db ) Stock Number (00697) mutation, ten male mice aged of 10 weeks with the leptin (B6.Cg- Lepob /J homozygotes ( ob/ob ) Stock Number (00632) mutation both experimental group on the C57BL/6J genetic background and three WT mice were used.…”

“…Serum and tissue fraction insulin concentrations were measured with commercially available ELISAs as we described earlier ( Pelletier et al, 2020a ). Briefly, STf and ITf were homogenized with a tissue grinder in an acid ethanol solution (180 mM HCl in 70% ethanol; 0.01 ml/mg tissue) on ice ( Vijay et al, 2008 ).…”

What do we know about blood-testis barrier? current understanding of its structure and physiology

“…Both TEM and permeability assay showed that BTB integrity was compromised in this model ( Fan et al, 2015 ). In the mouse testis, IF localization of Cx43, Cx46 and Cx50 was analyzed using models of diabetes and obesity ( Pelletier et al, 2018 ; Pelletier et al, 2020 ). 10.…”