Research Projects

Cardiomyopathies (CMs) are a heterogeneous group of pathologies characterized by structural and functional abnormalities in heart muscle1. Dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) are the two major types of CMs seen in humans, with an estimated prevalence of 1:500 individuals and 5-7 cases per 100,000 people, respectively1 2. Individuals with CM show impaired contractility and early mortality. Hence, identifying the genetic, molecular, and cellular processes that are the underlying cause of CM may help to develop pharmacological therapeutics to manage CM and improve the quality of life and increase the life span. Mutations in the genes that encode actin-binding proteins (ABPs) have been reported to be associated with the development of CM. The functions of ABPs are nucleation, regulation of polymerization and depolymerization, cross-link filaments, and anchoring of actin to other cellular components3. The nucleating protein formin homology-2 domain containing 3 (FHOD3) is one of the ABPs4. Recent studies in the Chinese5 and European6 populations identified that mutation in the FHOD leads to CMs. However, the underlying causes of the development of CMs due to the mutations in FHOD3 remained to be explored. To investigate the altered cellular and molecular processes leading to the development of CM pathogenesis due to the mutations in FHOD3, an animal model that closely mimics the cardiomyopathies seen in humans is required. Published evidence showed Fhod3 knockout mice are embryonic lethal7, hence, Fhod3 knockout mice model is not a suitable model for the above purposes. Our preliminary work on zebrafish showed that in contrast to mice and similar to humans, fhod3a mutants are adult viable and develop CM around 3 months post fertilization (mpf), visible by a pericardial protrusion (Figure 4). Hence, we propose to explore the underlying cellular and molecular mechanisms leading to the development of CM due to the mutation in the FHOD3 using fhod3a zebrafish mutants. To explore the spatiotemporal expression pattern of fhod3a and Fhod3a protein localization, mRNA in situ hybridization and immunohistochemistry will be performed, respectively. Tissue-specific transgenic fluorescence reporter lines will be employed to identify the cardiac phenotype. Live imaging, immunohistochemical analysis, and TEM will be performed to detect the onset and progression of CM. To understand the underlying molecular mechanism, comparative gene expression analysis will be performed between the wild-type and fhod3a-/- hearts at the earliest onset of the cardiac phenotype. Further, to establish the link between the identified altered signaling cascade(s) and cellular phenotype pharmacological and genetic tools will be utilized. Altogether, the proposed work will find the earliest alteration of signaling cascade(s) that perturbs the cardiac tissue structure and heart function progressively leading to CM in fhod3a mutants.