Proteomic screening of TMEM43 binding partners identifies VDAC leading to mitochondrial dysfunction

Area of Science:

• Molecular Biology
• Cardiovascular Research
• Cell Biology

Background:

• The transmembrane protein 43 (TMEM43) S358L mutation is prevalent in arrhythmogenic right ventricular cardiomyopathy type 5 (ARVC5).
• Understanding TMEM43 mutant interacting proteins is crucial for elucidating ARVC5 pathogenesis.

Purpose of the Study:

• To identify and characterize differential binding partners of TMEM43 and its S358L mutant.
• To investigate the functional consequences of altered protein interactions, particularly concerning mitochondrial function.

Main Methods:

• Quantitative immunoprecipitation (IP)-mass spectrometry (MS) was employed to screen for TMEM43 binding partners.
• Immunofluorescence (IF) staining and TurboID proximity-labeling were used for validation.
• Mitochondrial function assays were performed in cardiac myoblast H9c2 cells.

Main Results:

• 166 differential protein binding candidates were identified for TMEM43 p.S358L.
• Enrichment analysis revealed involvement in calcium signaling, lipid metabolism, and cardiovascular diseases.
• A significant decrease in voltage-dependent anion-selective channel proteins (VDAC1 and VDAC2) binding to the TMEM43 mutant was observed.
• Reduced VDAC binding correlated with mitochondrial dysfunction in cardiac cells expressing TMEM43 p.S358L.

Conclusions:

• This study provides a comprehensive interactome of TMEM43 p.S358L.
• The findings suggest TMEM43 plays a critical role in mitochondrial regulation.
• Altered VDAC binding by TMEM43 mutants contributes to the pathogenesis of ARVC5.