Rescue of perfluorooctanesulfonate (PFOS)-mediated Sertoli cell injury by overexpression of gap junction protein connexin 43

Abstract

Perfluorooctanesulfonate (PFOS) is an environmental toxicant used in developing countries, including China, as a stain repellent for clothing, carpets and draperies, but it has been banned in the U.S. and Canada since the late 2000s. PFOS perturbed the Sertoli cell tight junction (TJ)-permeability barrier, causing disruption of actin microfilaments in cell cytosol, perturbing the localization of cell junction proteins (e.g., occluden-ZO-1, N-cadherin-ß-catenin). These changes destabilized Sertoli cell blood-testis barrier (BTB) integrity. These findings suggest that human exposure to PFOS might induce BTB dysfunction and infertility. Interestingly, PFOS-induced Sertoli cell injury associated with a down-regulation of the gap junction (GJ) protein connexin43 (Cx43). We next investigated if overexpression of Cx43 in Sertoli cells could rescue the PFOS-induced cell injury. Indeed, overexpression of Cx43 in Sertoli cells with an established TJ-barrier blocked the disruption in PFOS-induced GJ-intercellular communication, resulting in the re-organization of actin microfilaments, which rendered them similar to those in control cells. Furthermore, cell adhesion proteins that utilized F-actin for attachment became properly distributed at the cell-cell interface, resealing the disrupted TJ-barrier. In summary, Cx43 is a good target that might be used to manage PFOS-induced reproductive dysfunction.

Perfluorooctanesulfonate (PFOS)-induced Sertoli cell injury through a disruption of F-actin and microtubule organization is mediated by Akt1/2

“…These observations thus suggest that there are other proteins and/or signaling pathways involved in modulating the SC79-mediated rescue efforts following PFOS exposure regarding re-organization of the actin- and MT-based cytoskeletons. This notion is supported by studies demonstrating that overexpression of connexin 43 (Cx43, a gap junction protein highly expressed in the testis 66 , 67 and a target of environmental toxicant 67 ) also intercepts the PFOS-induced BTB disruption and capable of rescuing PFOS-mediated F-actin disorganization 36 . For instance, in the absence of PFOS, Cx43 per se that is known to maintain the Sertoli cell TJ-permeability barrier function 68 , 69 might have conferred the TJ-barrier function to its maximal, thus, the presence of SC79, including the activation of p-Akt1-T308 and p-Akt1-S473 could no longer enhance the immunological barrier to make it “tighter”.…”

“…Lysates from Sertoli cells at specified time points were then obtained for immunoblotting using corresponding specific antibodies which were characterized earlier in our laboratory (Table 1 ) 35 , 36 . The steady-state levels of TJ-proteins occludin and CAR, and basal ES-proteins N-cadherin and ß-catenin, branched actin polymerization protein Arp3, barbed end capping and bundling protein Eps8, and actin nucleation protein formin 1 were not perturbed following PFOS treatment, but TJ-adaptor protein ZO-1 and actin bundling proteins palladin and plastin 3 were down-regulated (Fig.…”

Food‐grade titanium dioxide (E171) by solid or liquid matrix administration induces inflammation, germ cells sloughing in seminiferous tubules and blood‐testis barrier disruption in mice

“…Moreover, integral membrane proteins such as claudins and occludin in tight junctions are tied to the actin cytoskeleton by adaptor proteins, such as ZO‐1, ZO‐2 and ZO‐3, which distribution could be affected (Xu et al, ). For instance, ZO‐1, N‐cadherin and β‐catenin distribution was perturbed by perfluorooctanesulfonate, also causing disruption of actin microfilaments in cell cytosol and the tight junctions (Li et al, ).…”

Rescue of PFOS-induced human Sertoli cell injury by overexpressing a p-FAK-Y407E phosphomimetic mutant

“…the same amount of DMSO alone (vehicle control) for 24 hr. The selected concentrations of PFOS used in our experiments were based on pilot experiments and earlier reported 26 , 49 .…”

“…A short pulse of current (20 µA) for ~2 sec was sent through the cell epithelium and the resistance (in ohm) was recorded, which thus quantified the TJ-permeability barrier as described 51 . The electrode was placed on the two opposite ends of a bicameral unit, and these 4 TER readings were averaged as earlier described 49 . Blanks were obtained from fibronectin-coated bicameral units containing equal amount of culture medium without human Sertoli cells.…”