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Molecular Medicine |
From the Department of Cell Biology and Anatomy (L.S.R., K.M.H., P.B.A.); Department of Pharmacology and Toxicology (L.S.R., S.L., X.X., D.B., T.D.C.), College of Pharmacy; Steele Childrens Research Center (T.D.C.); and Bio5 Institute (T.D.C.), The University of Arizona, Tucson.
Correspondence to Todd D. Camenisch, PhD, University of Arizona, Department of Pharmacology and Toxicology, College of Pharmacy, 1703 E Mabel St, Tucson, AZ 85721. E-mail camenisch{at}pharmacy.arizona.edu
Cardiac malformations constitute the most common birth defects, of which heart septal and valve defects are the most frequent forms diagnosed in infancy. These cardiac structures arise from the endocardial cushions through dynamic interactions between cells and the extracellular matrix (cardiac jelly). Targeted deletion of the hyaluronan synthase-2 (Has2) gene in mice results in an absence of hyaluronan (HA), cardiac jelly, and endocardial cushions, a loss of vascular integrity, and death at embryonic day 9.5. Despite the requirements for Has2 and its product, HA, in the developing heart, little is known about the normal processing and removal of HA during development. Cell culture studies show that HA obtains new bioactivity after depolymerization into small oligosaccharides. We previously showed reduction in Has2 expression and diminished presence of HA at later stages of heart development as tissue remodeling formed the leaflets of the cardiac valves. Here we show that small oligosaccharide forms of HA (o-HA) act antagonistically to developmental epithelial-to-mesenchymal transformation (EMT), which is required to generate the progenitor cells that populate the endocardial cushions. We further show that o-HA induces vascular endothelial growth factor (VEGF), which acts as a negative regulator of EMT. This is the first report illustrating a functional link between oligosaccharide HA and VEGF. Collectively, our data indicate that following endocardial cell EMT, native HA is likely processed to o-HA, which stimulates VEGF activity to attenuate cardiac developmental EMT.
Key Words: epithelial-to-mesenchymal transformation VEGF hyaluronan endocardial cushion
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N. Itano Simple Primary Structure, Complex Turnover Regulation and Multiple Roles of Hyaluronan J. Biochem., August 1, 2008; 144(2): 131 - 137. [Abstract] [Full Text] [PDF] |
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