How cardiac fibroblasts react to cardiomyocyte signaling – focus on epigenetic signal integration

• Applicant: Privatdozent Dr. Justus Stenzig
• Subject Area: Pharmacology ; Cardiology, Angiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 528380599

Fibrosis is an almost universal feature of heart disease. To limit exaggerated fibrosis is clearly beneficial, but not sufficiently possible. The role of the cardiomyocytes in cardiac fibrosis is poorly defined. Identification of novel signaling pathways from cardiomyocytes to fibroblasts could lead to improved, heart-specific anti-fibrotic therapy. The aim of this project is to identify pathways of cardiac fibroblast activation which can be therapeutically harnessed in a heart-specific manner. We will study transcriptional regulation in cardiac fibroblasts with a focus on signals to the epigenome in order to i) advance the search for cardiac-specific anti-fibrotic therapies, ii) gain deeper insight into the role of epigenetics for cardiac fibroblast activation and iii) provide mechanistic insight with regard to previous findings arguing for a beneficial effect of DNMT inhibition in fibrosis-associated heart disease. The core experiment aims to identify co-regulated gene expression modules and epigenetic signatures for which both i) fibroblast activation and ii) the presence of cardiomyocytes are required. The combined transcriptional and epigenetic information will then guide the search for affected signaling pathways and their extracellular effectors, which are potentially accessible for therapeutic interventions. One epigenetic mechanism we aim to investigate in particular is DNA methylation. We and others have previously studied DNA methylation in heart disease and have observed anti-fibrotic properties of DNA methylation inhibition, which are currently unexplained. We will therefore extend our experiments and use the same experimental setup in the presence or absence of the DNA methylation machinery, to resolve the mechanism behind this observation. The work will be based on a novel model of 2-cell-type human engineered heart tissue containing both cardiac fibroblasts and cardiomyocytes (CF-EHT). In different models of both fibroblast and cardiomyocyte stress and activation, we will analyze gene expression and chromatin states with the idea to harness the information flow converging on the chromatin, in a reverse order, thus identifying peripheral signals which are integrated and stored as chromatin-based information. CF-EHT will be derived from human induced pluripotent stem cells (hiPSC) from both wild-type and DNA methyltransferase 3A (DNMT3A) knock-out cell-lines. Together with in silico-analysis of existing transcriptome data from other tissues, this will allow us to identify activation pathways specific to the physiological tissue context. Mass-spectrometry metabolome and proteome data from both EHT matrix and culture media will then serve to confirm the presence of upstream extracellular signaling molecules of potentially important pathways. We will then return to our initial model and use it for direct mechanistic validation of candidate pathways, which we will address by inhibiting compounds or by genetic interventions.

• DFG Programme: Research Grants