Hyperthermia differently affects connexin43 expression and gap junction permeability in skeletal myoblasts and HeLa cells.

Ieva Antanavičiūtė,Edgaras Stankevičius,Thomas Herdegen,Vida Mildažienė,Vytenis Arvydas Skeberdis

doi:10.1155/2014/748290

Abstract

Stress kinases can be activated by hyperthermia and modify the expression level and properties of membranous and intercellular channels. We examined the role of c-Jun NH2-terminal kinase (JNK) in hyperthermia-induced changes of connexin43 (Cx43) expression and permeability of Cx43 gap junctions (GJs) in the rabbit skeletal myoblasts (SkMs) and Cx43-EGFP transfected HeLa cells. Hyperthermia (42°C for 6 h) enhanced the activity of JNK and its target, the transcription factor c-Jun, in both SkMs and HeLa cells. In SkMs, hyperthermia caused a 3.2-fold increase in the total Cx43 protein level and enhanced the efficacy of GJ intercellular communication (GJIC). In striking contrast, hyperthermia reduced the total amount of Cx43 protein, the number of Cx43 channels in GJ plaques, the density of hemichannels in the cell membranes, and the efficiency of GJIC in HeLa cells. Both in SkMs and HeLa cells, these changes could be prevented by XG-102, a JNK inhibitor. In HeLa cells, the changes in Cx43 expression and GJIC under hyperthermic conditions were accompanied by JNK-dependent disorganization of actin cytoskeleton stress fibers while in SkMs, the actin cytoskeleton remained intact. These findings provide an attractive model to identify the regulatory players within signalosomes, which determine the cell-dependent outcomes of hyperthermia.

Highlights

Skeletal myoblasts (SkMs) have been investigated during the last decade for their potential in several fields of regenerative medicine
We examined the role of c-Jun NH2-terminal kinase (JNK) in hyperthermia-induced changes of connexin43 (Cx43) expression and permeability of Cx43 gap junctions (GJs) in the rabbit skeletal myoblasts (SkMs) and Cx43-EGFP transfected HeLa cells
The present study demonstrates that (i) in SkMs, hyperthermia induced the expression of Cx43 and enhanced the efficiency of GJ intercellular communication (GJIC) but did not affect the actin cytoskeleton; (ii) in Cx43-EGFP-transfected HeLa cells, hyperthermia reduced the Cx43-EGFP expression and the efficiency of GJIC and disrupted the actin cytoskeleton

Summary

Introduction

Skeletal myoblasts (SkMs) have been investigated during the last decade for their potential in several fields of regenerative medicine. SkMs are considered to be appropriate candidates for stem cell therapy due to their high proliferative potential, resistance to ischemia, simple isolation from muscular biopsy, and absence of tumorigenicity as well as of immunological and ethical concerns. Animal studies have shown positive effects of autologous SkM transplantation on the cardiac function [1, 6,7,8], but controversial data were obtained from phase I clinical trials, which failed to demonstrate the functionally effective postinfarctional heart regeneration with SkMs [9]. A number of issues need to be resolved concerning stem cell transplantation. Suzuki et al have shown that only 7.4% of SkMs survived in mice hearts 72 h after injection [10]. For the proper excitation of the heart, engrafted cells need to establish

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Conclusion