Identification of personalized treatments for Noonan syndrome via genotype-phenotype correlation in patient-specific iPSCs

• Applicant: Dr. Lukas Cyganek
• Subject Area: Cardiology, Angiology ; Developmental Biology ; Human Genetics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501985000

Infants with hypertrophic cardiomyopathy (HCM) as a symptom of Noonan syndrome (NS) display a significantly worse late survival compared with NS patients without HCM and are more likely to develop heart failure. However, treatment options are heavily limited. NS affects 1 in 1,000 to 2,500 newborns and is considered as the most common monogenetic disease associated with congenital heart defects, caused by germline mutations in genes that encode components or regulators of the RAS-MAPK signaling pathway, all leading to a hyperactivity of the signaling pathway. Although the underlying molecular mechanisms are poorly understood, a genotype-phenotype correlation in NS patients is expected. The divergence of disease-specific symptoms – such as the manifestation and severity of HCM versus no occurrence of HCM – suggest that the underlying molecular effects of genes might be overlapping but distinct. We postulate that the severity of cardiac dysfunction in NS patients depends on the level of RAS-MAPK hyperactivity, which in turn closely correlates with the underlying gene mutations. In addition, since the RAS-MAPK pathway is in constant crosstalk to other pathways – such as but not limited to the p38 MAPK, the PI3K/AKT or the NFκB signaling – the manifestation of HCM in NS could be also triggered by cross‐activation of these pathways. Our molecular and functional understanding might inform the choice (and dose) of available treatment options for NS patients.In order to gain new insights into the molecular pathology of individual NS cases in relation to their specific symptoms, we generated patient-specific as well as CRISPR-corrected induced pluripotent stem cells (iPSCs) from patients with various disease-causing gene variants along the RAS-MAPK signaling cascade that suffer from NS and comprise both patients that present with a moderate to severe form of HCM as well as patients without any HCM. Our iPSC spectrum together with the corresponding corrected isogenic controls comprises 34 different cell lines in total and will enable us to elucidate the genotype-phenotype correlation in a human model system. By characterizing the iPSC-derived cardiomyocytes on molecular, cellular, functional and 3D tissue level from the entire patient cohort, we aim to establish a correlation between the genotypes and the phenotypic profiles of the patients’ cells. By analyzing the global proteomic as well as the phospho-proteomic profiles of the patients’ cardiomyocytes, we aim to obtain a more global picture of the underlying signaling crosstalk and potential downstream targets that evoke the development of HCM, enabling clustering of patients according to their unique disease signatures. Ultimately, a preclinical drug screening approach based on selective compounds tailored to the particular genotypes and their unique disease signatures will evaluate the effects of distinct pathway inhibitors on the molecular and functional features of NS-affected cardiac cells.

• DFG Programme: Research Grants