Congenital Heart Disease (CHD) is the most common birth defect affecting approximately 1% of all live births in the US and is one of the leading causes of infant mortality. A severe form of CHD can result from Heterotaxy (Htx), a disorder of the left-right (LR) patterning during embryonic development. A recent genetic analysis of heterotaxy patients identified a novel CHD candidate gene, mink1. Mink1 encodes a serine-threonine germinal-center kinase with known functions in the JNK and PCP/Wnt signaling pathways. However, it has no known role in LR patterning or cardiac development. Using CRISPR knockout strategies in the high-throughput human disease model, Xenopus, loss of mink1 leads to cardiac and LR patterning defects, and defects in motile cilia formation and resulting fluid flow. The overall goal of this proposal is to investigate the molecular mechanism by which mink1 affects LR patterning, heart development, and cilia formation in the Xenopus (frog) model system.
The first aim will use loss of function experiments to determine the required role for mink1 during the LR patterning cascade b testing molecular markers. Mechanistic hypotheses will be guided by an analysis of temporal and spatial expression of mink1 in the whole embryo and the left-right organizer.
The second aim will use loss of function experiments to determine the requirement for mink1 during formation of motile cilia on the multi-ciliated cells of the Xenopus epidermis, which recapitulates a common mucociliary defect found in CHD patients. Hypotheses will be directed by a review of relevant literature including a role in regulation of multi-ciliated cell fate specification through Notch signaling or a requirement for Mink1 during basal body docking and/or establishment of polarity.
The third aim will determine the role of each mink1 domain in the context of cilia formation on multi-ciliated cells and LR patterning/cardiac development. Then it will be determined if the patient mutation in the kinase-encoding domain is determination to function using multiple functional assays in Xenopus. Altogether, these experiments will improve our understanding of cardiac development and the role of mink1 in the pathogenesis of CHD. In the future, this will benefit genetic testing and counseling, as well as improve outcomes in CHD because treatments can be tailored to genotype rather than solely on CHD phenotype. In addition, this application details the applicant's training plan including research mentorship, advanced coursework, training in new techniques, and the development of skills in scientific professionalism, writing, and presentation of data. The research and training outlined in this application will prepare the applicant to pursue a career performing patient-driven research as an independent research scientist.
Congenital Heart Disease (CHD) is one of the leading causes of infant mortality, affecting approximately 1% of all live births in the US. Studying the function of candidate genes identified in patients with CHD will improve our understanding of cardiac development and the pathogenesis of CHD, as well as bolster the evidence that a candidate gene may be disease causing. In the future, this will benefit genetic testing and counseling, as well as improve outcomes in CHD because treatments can be tailored to genotype rather than solely on CHD phenotype.