Magdalena Chrzanowska, PhD, FAHA
Magdalena Chrzanowska, PhD, FAHA
Senior Investigator and Program Leader
Transfusion Medicine, Vascular Biology and Cell Therapy
Associate Professor
Department of Pharmacology & Toxicology
Medical College of Wisconsin
Research Member
Medical College of Wisconsin Cancer Center
Medical College of Wisconsin Cardiovascular Center
Senior Investigator and Program Leader
Versiti Blood Research Institute
Education and training
MSc, Jagiellonian University, Krakow, Poland
PhD, University of North Carolina at Chapel Hill
Thrombosis, Hemostasis and Vascular Biology
My laboratory studies the function of small G proteins in the cardiovascular system. We use transgenic mouse and zebrafish models for in vivo studies and a variety of biochemical, molecular and microscopy approaches to interrogate signaling by small GTPases in vascular cells ex vivo.
Small G protein Rap1 has been the main focus of research in my laboratory over the past few years. Rap1, evolutionarily conserved and ubiquitously expressed, is activated downstream from multiple cell surface receptors and regulates several basic cellular functions: adhesion, migration, polarity, differentiation and growth.
Over the last decade, using total and conditional Rap1 knockout mice, my laboratory has discovered several key physiological functions of this small GTPase in the vasculature.
Angiogenesis and Regulation of VEGF Responses
Using Rap1-knockout mice, my laboratory discovered a novel role of Rap1 in vivo: regulation of angiogenesis. In an in vivo neonatal retinal model, and a Matrigel plugEndothelial Cell model, we demonstrated that Rap1-deficiency leads to a defect in angiogenesis; and through ex vivo and in vitro studies, we localized the defect to endothelial cells. We have shown that endothelial proliferation, migration, sprouting and permeability are affected by Rap1-deficiency. At the molecular level, the underlying mechanism involves defective activation and signaling downstream from Vascular Endothelial Growth Factor (VEGF) Receptor 2. Current research in my laboratory is focused on elucidating molecular mechanisms through which Rap1 regulates endothelial cell responses to VEGF promoting angiogenesis and investigating the role of Rap1 in pathological angiogenesis in vivo.
Vascular Homeostasis in Health and Disease
Studies from our laboratory, and others, have implicated Rap1 in the control of multiple stem cell, leukocyte and vascular cell functions. Mostly through in vitro studies, Rap1 has been implicated in maintaining epithelial and endothelial cell junction integrity and linked with cerebral cavernous malformations, a prevalent neurovascular syndrome that leads to seizures and lethal stroke. Through studies with endothelial-specific knockout mice, we determined that Rap1 in endothelial cells is required for vessel formation. Beyond development, Rap1 regulates vascular tone by promoting nitric oxide-dependent vasodilation and is required for maintenance of normal blood pressure. The significance of our findings is underscored by the phenotype of endothelial-specific Rap1 knockout mice, which develop endothelial dysfunction, hypertension and cardiac hypertrophy in vivo and die suddenly at 4-6 months old (males). Current research in my laboratory is focused on understanding molecular mechanisms through which Rap1 regulated endothelial homeostasis and on physiological consequences of Rap1-deficiency on endothelial dysfunction, in particular, progression of atherosclerosis.
Integration of Adhesion, Chemical and Mechanical Signals
In vitro studies of Rap1 function in endothelial cells have shown its importance in promoting integrin- and cadherin-mediated adhesion. Our in vivo analysis of endothelium-restricted Rap1-deficient mice demonstrates that Rap1 is particularly important for regulation of signaling by the adhesion molecules, rather than their adhesive functions. Furthermore, our recent studies of the role of Rap1 in endothelial cell response to shear stress demonstrate important function of Rap1 in transmission of mechanical signals. In response to shear stress, Rap1 promotes assembly of endothelial junctional mechanosensing complex, involving adhesion receptors PECAM-1 and VE-cadherin and VEGFR2, and downstream signaling required for normal nitric oxide release and endothelial function. Our current studies are focused on molecular mechanisms through which Rap1 promotes shear stress signaling under laminar, vaso-protective flow, and disturbed flow of blood that is associated with development of pro-inflammatory states and progression of atherosclerosis.