Signaling mechanisms in the regulation of cardiomyocyte cohesion in arrhythmogenic cardiomyopathy

Shoykhet, Maria (2023): Signaling mechanisms in the regulation of cardiomyocyte cohesion in arrhythmogenic cardiomyopathy. Dissertation, LMU München: Fakultät für Biologie

Abstract

Arrhythmogenic cardiomyopathy (AC) is a genetic disease, leading to fibro-fatty replacement of the myocardium, which untreated can lead to sudden cardiac death. One of the underlying mechanisms of AC is loss of cardiomyocyte cohesion due to mutations in genes coding for proteins of the intercalated disc (ICD), such as plakoglobin (PG), desmoplakin (DP), plakophilin 2 (PKP2) or desmoglein 2 (DSG2). In this work, several, in part interdependent mechanisms that stabilize cardiomyocyte cohesion were investigated. The Jup-/- murine AC model (Jup being the gene coding for PG), which shows arrhythmia and fibrosis was used in this work. Jup-/- mice had increased epidermal growth factor receptor (EGFR) levels and p38 mitogen activated protein kinase (p38MAPK) activation. EGFR levels were also increased in heart lysates obtained from Pkp2-/- mice, representing another AC model. Furthermore, EGFR levels were increased in AC patients’ hearts compared to dilated cardiomyopathy hearts, and EGFR localization at the ICD was found in AC patients’ hearts. Adrenergic signaling, protein kinase C (PKC) activation, p38MAPK, EGFR, SRC or A Disintegrin and Metalloprotease 17 (ADAM17) inhibition led to positive adhesiotropy in HL-1 cardiomyocytes and wildtype mice, and (apart from adrenergic signaling) also in Jup-/- mice. Positive adhesiotropy in HL-1 cardiomyocytes upon adrenergic signaling, PKC activation or p38MAPK inhibition was extracellular signal regulated kinase 1/2 (ERK1/2)-dependent under basal conditions but not upon hyperadhesion. In all cases but PKC activation, positive adhesiotropy in HL-1 cardiomyocytes was paralleled by an ERK1/2-dependent enhanced DSG2 localization at the membrane. DP localization at the membrane was enhanced upon inhibition of EGFR, SRC or ADAM17. In wildtype hearts, enhanced DSG2 and DP staining width at the ICD upon EGFR or SRC inhibition was observed, whereas in Jup-/- hearts, only DSG2 was enhanced at the ICD upon EGFR or SRC inhibition. Adrenergic signaling, PKC activation or p38MAPK inhibition-mediated positive adhesiotropy was dependent on the expression of PG, DP and DSG2 as well as ERK1/2 activity. Positive adhesiotropy upon EGFR or SRC inhibition was dependent on the expression of DP, but still effective upon Dsg2 knockdown. In contrast, positive adhesiotropy upon ADAM17 inhibition was dependent on the expression of Dsg2. EGFR inhibition activated the Rho associated kinase (ROCK), and positive adhesiotropy upon EGFR inhibition was achieved through ROCK-mediated enhanced desmosomal assembly. Together, these findings might not only pave the way to find new treatment options for AC by stabilizing cardiomyocyte cohesion, but could also be suited for other diseases with dysfunctional desmosomes.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
• Fakultäten: Fakultät für Biologie
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 1. Juni 2023
• 1. Bericht­erstatter:in: Leonhardt, Heinrich