Profiling Project





Plectin - Mouse AortaOne major focus of study in the Gimbrone laboratory has been the molecular mechanisms that mediate the localized interactions of leukocytes with the vascular endothelium at sites of acute and chronic inflammatory responses, and vascular injury and repair. Our working concept has been that endothelium-dependent mechanisms (in particular, inducible cell surface adhesion molecules and secreted cytokines/chemokines, such as IL-8 and MCP-1) are important local determinants of the spatial and temporal patterns of leukocyte-vessel wall interactions. Research accomplishments in this area include: 1) the demonstration in the early-mid 1980's, with colleagues in the Vascular Research Division, of the phenomenon of "endothelial activation" by proinflammatory cytokines and bacterial products (e.g., Gram-negative endotoxins); 2) the discovery of cytokine-inducible endothelial-leukocyte adhesions molecules (ELAMs), and the molecular cloning of ELAM-1 (E-selectin), the index member of a novel family of intercellular adhesion molecules called the "Selectins"; 3) the molecular cloning of a novel endothelial isoform of IL-8 and the demonstration of its role, in vitro and in vivo, as an endothelium-derived soluble inhibitor of leukocyte adhesion; 4) the discovery and molecular cloning of "ATHERO-ELAM", a mononuclear leukocyte-selective adhesion molecule that is expressed by the endothelium in the earliest atherosclerotic lesions in hypercholesterolemic preclinical models, and the demonstration of its homology with human VCAM-1 (vascular cell adhesion molecule-1); 5) the engineering (in collaboration with Dr. David Milstone in the Vascular Research Division) of an E-selectin-deficit mouse, which has been useful for various pathophysiological studies; 6) the development of techniques (in collaboration with the Vascular Research Division Cell Biology Core) for isolation and culture of microvascular endothelial cells from the lungs of genetically modified mice, for use in in vitro studies. Ongoing projects include: 1) detailed structure-function studies of the cytoplasmic domain of E-selectin and its role in transmembrane signalling during inflammatory leukocyte recruitment; 2) downstream consequences of E-selectin-mediated, leukocyte-adhesion-dependent signalling, in particular the modulation of endothelial phenotype, at the transcriptional level; 3) immunotargeting to cell surface endothelial activation antigens, such as E-selectin and VCAM-1, for diagnostic and therapeutic applications including vascular imaging and gene transfer.

EC and SMCA second major focus of activity in the Gimbrone Laboratory (which has evolved from a long-standing collaboration with Prof. C.F. Dewey and colleagues in the Fluid Mechanics Laboratory at the Massachusetts Institute of Technology) is the study of hemodynamic forces, such as wall shear stress, as modulators of vascular endothelial structure and function. Specially designed in vitro flow devices are used to expose cultured endothelial monolayers to defined laminar, disturbed laminar, and turbulent flow regimens, and the resultant morphological, biochemical and molecular genetic changes are studied in the context of vascular adaptation, and also the pathogenesis of vascular diseases, in particular atherosclerosis. Research contributions in this area include: 1) the demonstration that shear stresses can differentially regulate important aspects of endothelial cell biology, including cell shape and cytoskeletal organization, cell growth and apoptosis, cell endocytosis and secretion, and gene expression; 2) the discovery and characterization of "shear stress response elements (SSREs)" in the promoters of certain biologically important, endothelial-expressed genes, that mediate their induction by biomechanical forces; 3) the demonstration, by high-through-put genomic strategies (such as differential display of expressed transcripts and cDNA microarrays), that endothelial gene expression can be profoundly influenced by different types of biomechanical input stimuli; 4) the demonstration that the biomechanical milieu of so-called atherosclerosis-resistant arterial geometries may favor the sustained upregulation of critical "athero-protective genes" in the endothelium (the "Athero-protective Gene Hypothesis"); 5) the discovery of several novel genes (e.g., Smad 6, Smad 7) whose expression in endothelium is biomechanically regulated and potentially relevant to vascular homeostasis. Ongoing studies include: 1) in vitro modeling of the effects of dynamic (arterial waveform) flow patterns on endothelial functional phenotype; 2) in-depth analyses of the patterns of gene expression induced by different biomechanical forces in cultured endothelial cells, utilizing genome-wide transcriptional profiling strategies; 3) extension of these studies to the endothelial lining of vessels in vivo, in both animal models and human vascular specimens (normal and diseased).

Transcriptional ProfilingFinally, the Gimbrone Laboratory has undertaken a systematic approach to defining phenotypic modulation of vascular endothelium, in health and disease, utilizing state-of-the-art techniques for transcriptional profiling of endothelial gene expression, in vitro and in vivo. It is our intent that the experimental databases resulting from these studies will be made available via this website for use by the vascular biology community.






home | projects | members | publications | links
transcriptional profiling project | vascular research division



Visitors since December 2, 2005