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Dysferlin stabilizes membrane nanodomains of cardiomyocytes after myocardial infarction

ABSTRACT: BACKGROUND: Despite significant advances in acute care medicine, myocardial infarction (MI) remains a predominant cause of premature death and heart failure. In the infarct border zone, cardiomyocytes are exposed to high biomechanical stress that impairs the integrity of the sarcolemmal membrane. Here, we hypothesized that the Ca2+-sensitive membrane repair protein dysferlin is key to preserving sarcolemmal nanodomains like the transverse-axial tubule (TAT) endomembrane network and the intercalated disc (ICD) membrane folds in the infarct border zone. METHODS: We employed permanent left anterior descending artery ligation to induce MI in mice, and used data-independent acquisition mass spectrometry (DIA-MS) to analyze the spatial proteomic profile in wild-type versus dysferlin-knockout hearts post-MI. Stimulated emission depletion (STED) nanoscopy and electron tomography were applied to study membrane nanodomain remodeling and dissect the role of dysferlin in local membrane protection and repair in cardiomyocytes of the infarct border zone. Co-immunoprecipitation-based DIA-MS and complexome profiling were used to further decode the cardiac interactome of dysferlin. RESULTS: DIA-MS quantitatively analyzed 5,700 proteins, segregating the proteomic profiles of the left-ventricular infarct zone, border zone and remote zone in wild-type versus dysferlin-knockout mice one week post-MI. While dysferlin protein expression was significantly upregulated in the MI border and remote zone, dysferlin-knockout mice presented larger infarct sizes and reduced left-ventricular systolic function post-MI. In cardiomyocytes of the WT infarct border zone, STED nanoscopy visualized severely disrupted TAT membranes and enlarged ICD membrane folds. Importantly, extensive dysferlin signals clustered in nanometric proximity to residual TAT structures and connexin-43 plaques at the ICD, stabilizing functional nanodomain organization for preserved excitation-contraction coupling and intercellular communication. Interactomic analyses revealed connexin-43 as a novel dysferlin interaction partner.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Heart, Left Ventricle

DISEASE(S): Myocardial Infarction

SUBMITTER: Christof Lenz

LAB HEAD: Christof Lenz

PROVIDER: PXD060259 | Pride | 2026-04-06

REPOSITORIES: Pride

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			Action	DRS
	20230520_102135_2023_22_S_Brandenburg_310323_Dysferlin.sne	Other
	2023_22_S_Brandenburg_SDRF.tsv	Tabular
	S_Brandenburg_310323_110423_DIA_A_02_BC2_1_9974.d.zip	Other
	S_Brandenburg_310323_110423_DIA_A_03_BC3_1_9975.d.zip	Other
	S_Brandenburg_310323_110423_DIA_A_04_BC4_1_9976.d.zip	Other

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Project description:BACKGROUND: Despite significant advances in acute care medicine, myocardial infarction (MI) remains a predominant cause of premature death and heart failure. In the infarct border zone, cardiomyocytes are exposed to high biomechanical stress that impairs the integrity of the sarcolemmal membrane. Here, we hypothesized that the Ca2+-sensitive membrane repair protein dysferlin is key to preserving sarcolemmal nanodomains like the transverse-axial tubule (TAT) endomembrane network and the intercalated disc (ICD) membrane folds in the infarct border zone. METHODS: We employed permanent left anterior descending artery ligation to induce MI in mice, and used data-independent acquisition mass spectrometry (DIA-MS) to analyze the spatial proteomic profile in wild-type versus dysferlin-knockout hearts post-MI. Stimulated emission depletion (STED) nanoscopy and electron tomography were applied to study membrane nanodomain remodeling and dissect the role of dysferlin in local membrane protection and repair in cardiomyocytes of the infarct border zone. Co-immunoprecipitation-based DIA-MS and complexome profiling were used to further decode the cardiac interactome of dysferlin. RESULTS: DIA-MS quantitatively analyzed 5,700 proteins, segregating the proteomic profiles of the left-ventricular infarct zone, border zone and remote zone in wild-type versus dysferlin-knockout mice one week post-MI. While dysferlin protein expression was significantly upregulated in the MI border and remote zone, dysferlin-knockout mice presented larger infarct sizes and reduced left-ventricular systolic function post-MI. In cardiomyocytes of the WT infarct border zone, STED nanoscopy visualized severely disrupted TAT membranes and enlarged ICD membrane folds. Importantly, extensive dysferlin signals clustered in nanometric proximity to residual TAT structures and connexin-43 plaques at the ICD, stabilizing functional nanodomain organization for preserved excitation-contraction coupling and intercellular communication. Interactomic analyses revealed connexin-43 as a novel dysferlin interaction partner.

Project description:BACKGROUND: Cardiac hypertrophy compensates for increased biomechanical stress of the heart induced by prevalent cardiovascular pathologies, but can result in cardiac failure if left untreated. We hypothesized that the tail-anchored protein Dysferlin with multiple Ca2+-binding C2-domains is critical for the integrity of the transverse-axial tubule (TAT) network inside cardiomyocytes, and contributes to the proliferation of TAT endomembranes during pressure overload-induced cardiac hypertrophy. OBJECTIVE: To reveal the impact of the membrane fusion and repair protein Dysferlin on TAT network stabilization and proliferation necessary for the hypertrophic growth of cardiomyocytes. METHODS AND RESULTS: Super-resolution light and electron microscopy of mouse cardiomyocytes identified a specific localization of Dysferlin in a vesicular compartment in nanometric proximity to contact sites of the TAT network with the sarcoplasmic reticulum (SR), a.k.a. junctional complexes for Ca2+-induced Ca2+ release. Mass spectrometry was used to characterize the cardiac Dysferlin interactome, thereby identifying a novel protein interaction with the membrane-tethering SR protein Juncophilin-2, a known interactor of L-type Ca2+ channels and Ryanodine Receptor Ca2+ release channels in junctional complexes. While the Dysferlin knockout caused a mild progressive phenotype of dilated cardiomyopathy in the mouse heart, global proteome analysis revealed changes preceding systolic failure. Following transverse aortic constriction (TAC), Dysferlin protein expression was significantly increased in hypertrophied wild-type myocardium, while Dysferlin knockout animals presented markedly reduced left-ventricular hypertrophy. Live-cell membrane imaging demonstrated a profound reorganization of the TAT network in wild-type left-ventricular myocytes post-TAC with robust proliferation of axial tubules, which critically depended on the increased expression of Dysferlin within newly-emerging tubule components. CONCLUSIONS: Dysferlin represents a new molecular target in cardiac disease that protects the integrity of tubule-SR junctional complexes for regulated excitation-contraction coupling, and controls TAT network reorganization and tubular membrane proliferation in cardiomyocyte hypertrophy induced by pressure-overload.

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Dysferlin stabilizes membrane nanodomains of cardiomyocytes after myocardial infarction

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