Many diseases such as stroke, diabetic retinopathy, atherosclerosis, restenosis, and cancer have known connections to vascular dysfunction and in particular targeted disruptions in mural cell (MC) support of blood vessels. MCs are a perivascular cell population that provides structural support to EC tube networks, and can be split into subclasses—including smooth muscle cells and pericytes. EC-MC interactions are known to be critical in stabilizing the vasculature by helping to withstand forces such as high shear stress/pulsatile pressure exerted on the vessels from blood flow coming out of the heart. MCs also promote barrier function at the blood brain barrier (BBB). Despite the critical nature of these cell-to-cell interactions, much more is known about genes regulating EC versus MC function, even though multiple vascular diseases have clear links to MC dysfunction. Therefore, understanding of how normal MCs function is critical to effectively develop specific therapeutics targeted at prevention and treatment of disorders.
The labs long-term research interests center on understanding MC biology during development and disease. We use zebrafish—a genetically accessible model system—coupled with in vitro 3D modeling assays, to study MC development and behavior. Zebrafish as a vertebrate model organism offer several advantages for the study of vascular development—including external fertilization, proper embryonic growth in the absence of functional vasculature or blood flow, and importantly optical clarity for live confocal and light sheet imaging.
The field remains largely uncharted giving us the unique opportunity to exploit newly developed tools to broaden the understanding of MC biology and the mechanisms regulating their behavior. Research in the laboratory aids in the understanding of developmental processes regulating MC function and in turn 1) provides a broader understanding of how blood vessels are assembled; 2) defines genetic pathways critical for MC function; and 3) provides a platform to assess dysfunction in EC-MC interactions during disease.
The lab has significant interest in understanding how sensing of forces—such as shear stress and axial strain—by vessels alters their development and stabilization. To this end, we study a number of genetic regulators of this process:
The lab has significant interest in how ion channels respond to mechanical inputs, and if changes in ion channel function alter mural cell association and targeting to vessels. To this end we study a series of ion channels—both independently and in collaboration—to parse apart this process. Our current focuses are on Piezo1, TRPM4/5, and SWELL channels. The goal is to understand how these channels interface with transcriptional programs in cells to alter their cell fate, differentiation, and motility choices.
We have a focus in the lab on the role of primary cilia on vascular development. We hypothesize that endothelial cilia sense blood flow to influence MC recruitment to the developing vasculature. Intriguingly, we detect endothelial cilia mainly on the abluminal side of the large vessels in early-stage zebrafish embryos, suggesting that cilia may sense blood flow at this timepoint through cyclic stretch as opposed to shear stress. Our objectives through these studies are to determine the orientation and distribution of endothelial cilia, to demonstrate how they respond to blood flow forces during development, and to define cilia linked signaling mechanisms directing cardiovascular stabilization.
The requirement of mechanical forces for cardiovascular remodeling events in both the heart and large blood vessels has been studied for decades; however, significant opportunity remains for the identification of novel signaling pathways that can integrate force with changes in cellular activity. Capitalizing on the use of ribosomal profiling tools in the zebrafish (TRAP-Seq) to isolate cell type specific translating mRNAs, we have identified CXCR3-CXCL11 as a novel candidate pathway in endothelial cells that serves this function. As a chemokine receptor-ligand pair, CXCR3-CXCL11 is typically studied for its role in promoting the adaptive immune response. However, we describe a role for this pathway in regulating endothelial cell function directly by delimiting cardiovascular outgrowth.
We recently identified a novel zebrafish mutant in the exon 12/13 splice acceptor site of dync1li1 that C-terminally truncates the protein, leading to an increase in blood vessel growth. Dynein cytoplasmic 1 light intermediate chain 1 (dync1li1) is a core member of the dynein motor complex, and defects in this gene are predicted to alter Rab binding capacity and cargo trafficking. The domain structure of Dync1li1 allows it to interact with cargo adaptors while simultaneously being integrated into the dynein motor complex. These adaptors are multifunctional proteins that serve as docking sites for other proteins to control endosome targeting. We are interested in how changes in Dync1li1 protein structure modify cargo selection and transport to alter angiogenesis and blood vessel development.