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  3. A potential therapeutic target at Connexin 43 serine phosphorylation against ischaemia/reperfusion arrhythmia

A potential therapeutic target at Connexin 43 serine phosphorylation against ischaemia/reperfusion arrhythmia

  • Br J Pharmacol. 2025 Jun 9. doi: 10.1111/bph.70090.
Zhiping Fu 1,  Shuanglei Li 2,  Jingyi Xue 1,  Qiang Li 1,  Tianhui Jiang 1,  Lulin Wu 1,  Luqi Wang 1,  Hanying Zhang 1,  Xin Geng 1,  Xintong Guo 1,  Xinxin Yan 1,  Hongjie You 1,  Lingxi Zhang 1,  Yimeng Zhang 1,  Tao Song 3,  Yongquan Wu 4,  Xiaofeng Yu 5,  Yunlong Hou 2,  Dali Luo 1
Affiliations

Affiliations

  • 1 Department of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, China.
  • 2 Division of Adult Cardiac Surgery, Senior Department of Cardiology, The Sixth Medical Center of PLA General Hospital, Beijing, China.
  • 3 National Key Laboratories for Innovation and Transformation of Luobing Theory, and State of Administration of TCM (Cardio-Cerebral Vessel Collateral Disease), Shijiazhuang Yiling Pharmaceutical Co., Ltd, Shijiazhuang, China.
  • 4 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
  • 5 Cyagen Biosciences, Taicang City, China.
PMID: 40490933 DOI: 10.1111/bph.70090
Abstract

Background and purpose: Dephosphorylation of several phosphor residues in connexin 43 (Cx43) is critically involved in ischaemia/reperfusion (I/R) arrhythmias. Here, we sought to identify constitutive Cx43-serine 282 (S282) dephosphorylation as an independent and targetable substrate to delineate reperfusion arrhythmogenesis.

Experimental approach: Reperfusion arrhythmias were induced by rat I/R (15/45 min), identified in heterozygous knock-in mice with S282 to alanine (Cx43-S282A/+) and rescued by LB100, a specific protein Phosphatase 2A (PP2A) inhibitor, via surface electrocardiogram and epicardial mapping detections. TAT-HA-L2, a mimic of Cx43-cytoplasmic-loop domain (L2), was assessed in mitigating Cx43-S282 dephosphorylation-associated arrhythmogenicity.

Key results: Upon I/R, rats exeperienced myocardium injury, ventricular tachycardia/fibrillation, increased PP2A activity and Cx43-S282 hypophosphorylation, whereas Cx43-S282A/+ mice had spontaneous ventricular arrhythmias with normal cardiac function/morphology. LB100 significantly attenuated these arrhythmias by restoring PP2A-C and Cx43-S282 phosphorylation. Slow and irregular electrical conduction, premature CA2+ transients and afterdepolarisations were found and normalised by LB100, or Gap19 peptide treatment (Cx43 hemichannel inhibitor), in Cx43-S282A/+ ventricles. Mechanistically, serine 282 locates within SH3-binding domain of the Cx43-carboxyl-terminus. TAT-HA-L2 bound with Cx43-S282 dephosphorylated proteins in S282A-expressed HeLa cells, as well as in S282A/+ and I/R isolated cardiomyocytes, more than in their counterpart controls. LB100 can prevent their enhanced binding and ATP release because of S282 dephosphorylation.

Conclusions and implications: Cx43-S282 dephosphorylation can trigger reperfusion arrhythmias by impairing gap junction intercellular communication while favouring hemichannel permeability. An up-regulated intramolecular interaction between L2 and Cx43-carboxyl-terminus is associated with this arrhythmogenicity, providing a novel and targetable mechanism to preserve the heart from ischaemia/reperfusion arrhythmias.

Keywords

Connexin 43 phosphorylation; LB100; SH3‐binding domain; arrhythmia; ischaemia/reperfusion; protein phosphatase 2A.

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