Phosphatase-Resistant Gap Junctions Inhibit Pathological Remodeling and Prevent Arrhythmias

Abstract

Rationale Post-translational phosphorylation of connexin43 (Cx43) has been proposed as a key regulatory event in normal cardiac gap junction expression and pathologic gap junction remodeling. Nonetheless, the role of Cx43 phosphorylation in the context of the intact organism is poorly understood. Objective To establish whether specific connexin43 phosphorylation events influence gap junction expression and pathologic remodeling. Methods and Results We generated Cx43 germline knock-in mice in which serines 325/328/330 were replaced with phosphomimetic glutamic acids (S3E) or non-phosphorylatable alanines (S3A). The S3E mice were resistant to acute and chronic pathologic gap junction remodeling (GJR) and displayed diminished susceptibility to the induction of ventricular arrhythmias. Conversely, the S3A mice showed deleterious effects on cardiac gap junction formation and function, developed electrical remodeling and were highly susceptible to inducible arrhythmias. Conclusions These data demonstrate a mechanistic link between post-translational phosphorylation of Cx43 and gap junction formation, remodeling and arrhythmic susceptibility.

Effect of Carbenoxolone on Arrhythmogenesis in Rat Ventricular Muscle

“…As shown in Figure 1 Experimental Protocol With Trabeculae Non-uniform muscle contraction was produced with a 2,3-butanedione monoxime (BDM) jet as previously reported. 3, 28 The equivalent diffusion coefficient for fura-2 was first calculated without electrical stimulation before, just after, and 1 h after superfusion with 5 …”

Connexins as Substrates for Protein Kinases and Phosphoprotein Phosphatases

“…The only available report to date using this approach showed that mice in which Cx43 was replaced by a Cx43 mutant at the CK1 sites in which serines 325/328/330 were replaced with phosphomimetic glutamic acids (S3E) were resistant to gap junction remodeling and less susceptible to the induction of arrhythmias. In contrast, mice in which a Cx43 mutant with serines 325/328/330 mutated to non-phosphorylatable alanines (S3A) was knocked-in in place of Cx43 had severe alterations in gap junction formation and function, and had a proarrhythmic phenotype (Remo et al, 2011). This report shows a mechanistic link between the phosphorylation state of Cx43 and arrhythmic susceptibility (Remo et al, 2011).…”

“…In contrast, mice in which a Cx43 mutant with serines 325/328/330 mutated to non-phosphorylatable alanines (S3A) was knocked-in in place of Cx43 had severe alterations in gap junction formation and function, and had a proarrhythmic phenotype (Remo et al, 2011). This report shows a mechanistic link between the phosphorylation state of Cx43 and arrhythmic susceptibility (Remo et al, 2011).…”

“…Mutagenesis of the identified phosphorylation sites has been used to determine the functional consequences of their phosphorylation/dephosphorylation in cultured cells as well as in vivo after transfection or knock-in of a phosphosite-directed mutant Cx (Lampe et al, 1998;Remo et al, 2011).…”

MicroRNAs as regulators of connexin-43 expression

“…In recent years the role of miRNAs in cancer has been demonstrated in many types of tumors including glioblastomas where they can control processes such as proliferation, invasion, angiogenesis and apoptosis [12] . Interestingly, some miRNAs involved in gliomagenesis downregulate Cx43 expression.…”