Project Details
Projekt
Modelling proteostasis in dilated cardiomyopathy - the role of BAG3 and the HSP70 system
Subject Area
Cardiology, Angiology
Term
from 2018 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 402866991
Studying genetically determined, primary cardiomyopathies is an auspicious approach for establishing basic disease mechanisms and novel therapeutic options in myocardial disease. One such potential molecular target is Bcl-2-associated athanogene 3 (BAG3) that is mutated in primary dilated cardiomyopathy (DCM). BAG3 serves as nucleotide exchange factor (NEF) for heat shock protein 70 family members (HSP70s), which regulate protein folding and degradation pathways.In this proposal we aim to explore the molecular mechanism how mutation of the BAG3 BAG domain affect the biochemical function of constitutive HSPA8, perturb protein homeostasis (proteostasis) in cardiomyocytes, and finally lead to DCM. We hypothesize that DCM missense mutations within the BAG3 BAG domain specifically disturb the NEF function of BAG3. Thus, we will explore biochemically the activity of the BAG3/HSPA8 complex using in vitro chaperone assays. Specifically, we will model a novel missense mutation from a large DCM family in isogenic induced pluripotent stem cells (iPSC). Using these iPSCs we will differentiate cardiomyocytes that we further analyze for protein aggregate formation, proteostasis, autophagy, and proteasome activity. The molecular network of co-chaperones associated with HSPA8 is not well understood in cardiomyocytes. We will use proteome data from iPSC derived cardiomyocytes and in vitro chaperone assays to characterize the composition as well as activity of the cardiac specific HSPA8 complex. As we observe a considerable phenotypic variability in patients of this DCM family, we will utilize iPSCs from patients and control individuals in proteome and RNAseq expression studies to search for cardio protective factors. Lastly, we aim to characterize the BAG3 associated heart phenotype on pathophysiological and molecular level in a transgenic zebrafish model. The analysis of specific BAG3 missense mutations will help to explore the molecular mechanism how BAG3 affects proteostasis in post-mitotic cardiomyocytes and consequently induces DCM. Our long-term goal is to translate our mechanistic findings and technical toolbox into therapeutic approaches targeting DCM.
DFG Programme
Research Grants
