Meeting Abstract
Missteps in formation of the embryonic heart can have drastic consequences, making cardiac malformations one of the most common human birth defects. Abnormalities in blood flow, which start before the vertebrate heart is fully formed, are just one of the factors that may contribute to these malformations. Flow is not directly encoded by genes, but has an impact on heart development via the frictional force of blood. This force, known as shear stress, acts on the endocardial cells in the developing heart. The goal of our research is to investigate how altered shear stress on endocardial cells leads to genetic responses in the heart, and to define the genes responsible. The zinc finger transcription factor Kruppel-like factor 2 (KLF2) is a potential flow response gene that may link shear stress signals to changes in gene expression in vertebrates. Here, we investigate three zebrafish genes similar in sequence to mammalian KLF2: klf2a, klf2b, and klf4. To understand how alterations in shear stress trigger altered gene expression in endocardial cells, we used comparative qPCR to investigate klf2a, klf2b, and klf4 expression levels in embryonic hearts subjected to altered shear stress conditions. Knockdown of the hematopoiesis genes gata1 and gata2 will lower hematocrit and alter blood viscosity, thereby altering shear stress within the embryonic heart in a defined manner. To discover Klf2-activated target genes, we will perform ChIP-seq on hearts of transgenic fish that express endocardial/vascular-specific Klf2a-eGFP fusion protein. Following validation, Klf2a target genes will be investigated by gene knockdown studies to define their functional roles in the heart. These studies will help identify the genes and molecular mechanisms involved in the cellular response to altered shear stress.
