The serine biosynthetic pathway as a novel therapeutic target for familial dilated cardiomyopathy.

• Applicant: Dr. Timon Seeger
• Subject Area: Cardiology, Angiology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462241601

Dilated cardiomyopathy (DCM) is a common cause of heart failure and is characterized by an enlargement of the left heart as well as a severe reduction of the pumping function. Genetic mutations are increasingly being identified as causal for DCM, however, the exact molecular and cellular mechanisms of how the genotype leads to the phenotype are only rudimentary known, not at last because of insufficient research models. Induced pluripotent stem cells (iPSCs) can be generated from any human individual by reprogramming of body cells (e.g. skin cells or blood cells). Subsequently, iPSCs can be differentiated into any body cell, including cardiomyocytes (iPSC-CMs). In preliminary data, iPSC-CMs from patients with DCM mutation in the gene troponin T showed a significantly reduced contractility compared to iPSC-CMs after correction of the mutation by genome editing (isogenic comparisons). Kinases regulate entire signaling cascades and thus influence complex cellular functions. We have established our in vitro DCM model as a screening tool, and investigated 160 kinase inhibitors with respect to their effects on contractility in DCM in order to identify novel therapeutic approaches. We identified dual inhibition (PPi) of protein kinase C (PKC) and p38 mitogen-activated protein kinase (MAPK) as contraction enhancing. In preliminary studies we identified a significant activation of the serine biosynthesis pathway in DCM iPSC-CMs in the context of PPi treatment, as well as an upregulation of the serine metabolism regulator activating transcription factor 4 (ATF4) and module of tribbles homologue 3 (TRIB3). In this research project, the roles of serine metabolism and the ATF4/TRIB3 signaling cascade in the regulation of contraction of human cardiomyocytes will be investigated. In particular, the direct link between PPi treatment and serine metabolism will be identified, especially with regard to the regulation of contractility. Furthermore, ATF4 and TRIB3 will be investigated as significant regulators in this interaction. On the other hand, serine biosynthesis pathway and ATF4/TRIB3 will be investigated as new therapeutic approaches in genetic DCM. For this purpose, 10 additional patients with genetic DCM as well as 3 healthy controls will be included and iPSCs will be generated. In this "clinical trial in a dish" the PPi treatment will be investigated with regard to contractility and activation of serine metabolism. In addition, the combination of specific drugs for the inhibition of PKC and MAPK, which are already individually being tested in clinical trials, will be evaluated. Finally, the results will be reproduced in vivo in a DCM mouse model with a TNNT2 mutation.

• DFG Programme: Research Grants
• International Connection: USA
• Cooperation Partner: Professor Ioannis Karakikes