Susan L. Bellis, PhD
Professor of Cell, Developmental and Integrative Biology
|Address:||Mccallum Building, 982A
Birmingham, AL 35294
Ph.D. (Biochemistry), University of Rhode Island
Post-doctoral Fellow, SUNY Health Science Center in Syracuse, NY
My research interests center on the role that integrin adhesion receptors play in the maintenance of normal cellular behavior, as well as in the development of diseases such as arthritis and cancer. There are two principal projects that we are currently pursuing:
Role of sialylation in regulating integrin-mediated cell adhesion, motility and cell survival. Our laboratory has shown that the expression of variantly-glycosylated b1 integrins is induced by signal transduction cascades, particularly those involving the ras family of small G proteins. One of the major modifications in glycosylation involves a change in the level of sialic acid, a negatively-charged sugar. Altered integrin sialylation occurs during monocyte/macrophage differentiation, T cell activation and epithelial cell transformation, suggesting that variant sialylation is a fundamental mechanism for integrin regulation. Differential sialylation is due to ras-dependent changes in expression of the ST6Gal I sialyltransferase, an enzyme that targets b1, but not b3 or b5, integrin subunits. Most importantly, variant integrin sialylation has a marked effect on several integrin-dependent events including cell adhesion to matrix, cell motility and invasion, and cell resistance to galectin-mediated apoptosis. We hypothesize that sialylation-dependent regulation of integrins contributes to both tumor progression, and monocyte/macrophage trafficking.
Development of biomimetic biomaterials for orthopaedic applications. The osseointegration and stability of an orthopaedic implant requires mesenchymal stem cell (MSC) attachment to the implant, followed by osteoblastic differentiation of these cells, and finally, new bone synthesis at the implant surface. To better understand the molecular mechanisms that regulate this process, we are defining the adhesion molecules and extracellular matrix components that direct attachment of MSCs to selected implant biomaterials. We are also using electrospinning technology to synthesize novel biomimetic biomaterials for bone tissue engineering applications. These porous, biodegradable materials are composed of molecules normally found within the bone matrix, for example, collagen I and hydroxyapatite. The goal of these studies is to create a resorbable material that, upon placement in the body, will be completely replaced with native bone over time.