Research
There are three main research areas in the Mosher lab.
Thrombospondin
There are five described thrombospondin genes in vertebrates and one in flies. Thrombospondins are large multi-modular extracellular matrix glycometalloproteins, with many diverse functions and binding 90 calcium ions or perhaps more. We are interested in the communication among the different modules within thrombospondins and how the protein is regulated by calcium concentration. In addition, single nucleotide polymorphisms (SNPs) of the genes for human thrombospondin-1, -2, and -4 have been linked to premature coronary artery disease and over 100 mutations of thrombospondin-5 cause skeletal malformations. We are using recombinant baculoviruses to express multi-modular segments of thrombospondins and carry out pioneering studies that give insight into the structural oraganization of thrombospondins and how the genetic alterations may cause pathophysiology. We are currently using antibody-mapping experiments, genetic manipulation of Drosophila melanogaster, NMR, X-ray crystallography, differential scanning calorimetry, isothermal titration calorimetry, intrinsic fluorescence, circular dichroism, mass spectroscopy, and other biochemical and biophysical techniques to examine the structure of thrombospondin and also its role in disease.
Please refer to the individual lab member pages for specific projects.
Model of a thrombospondin trimer, based on crystal and NMR structures from various labs.
Fibronectin
Accumulation of platelets leading to thrombosis and embolization at sites of vascular or tissue injury is crucial for formation of the hemostatic plug and arrest of bleeding. Excess thrombosis and embolization also contributes to and can be a cause of heart attack or stroke. Fibronectin (FN), an abundant extracellular matrix (ECM) and plasma glycoprotein, has been found to play an essential role in these processes and has been suspected of playing a role in platelet biology for nearly three decades. It contains a variety of known cell receptor and protein binding domains important for incorporation into thrombi and adhesive events during thrombosis. The involvement of FN assembly in clotting at sites of injury promotes cell and platelet attachment via surface receptors leading to a variety of signaling events. Our research is focused on elucidating the requirements for FN assembly by platelets, as well as fibroblasts, and the roles that FN assembly plays in homeostasis and thrombosis.
Please refer to the individal lab member pages for specific projects.
Assembly of exogenous FITC-Fibronectin (green) by FN-/- fibroblasts adherent to (A.) fibronectin or (B.) vitronectin. Vinculin staining is red.
Eosinophils in Asthma
Eosinophils are a type of white blood cell believed to have roles in asthma. Several lines of evidence indicate that movement of eosinophils from blood to the airway contributes to both asthma exacerbations and to the chronic character of the disease. Cell adhesion receptors of the integrin family are involved in several steps of this movement, including rolling and arrest on activated lung endothelial cells, extravasation and migration through endothelium and tissue to the airway. We are particularly interested in some phenomena that we believe are important in this process: 1) Activation of alpha4beta1 integrin (which is a receptor for vascular adhesion molecule-1 or VCAM-1 expressed on activated lung endothelium in asthmatics) on circulating blood eosinophils and the role of such activation for selective movement of eosinophils to the airway; and 2) Activation of alphaMbeta2 integrin (which is a receptor for diverse protein ligands), which occurs en route from blood to airway and formation of transient adhesive structures, called podosomes, which contain the metalloproteinase ADAM8, appear to mediate proteolysis of adhesive or extracellular matrix proteins, and likely are important for eosinophil movement through endothelium and tissue. We span the spectrum from basic cell-biological research to analyses of clinical samples in collaboration with the UW Hospital, and use various scientific methods and assays, including flow cytometry, immunofluorescence microscopy, cell adhesion assays under static and physiological flow conditions, and in vitro assays for activities of recombinant proteins
Please refer to the individual lab member pages for specific projects.
An eosinophil with podosomes on a substrate coated with VCAM-1. B: Eosinophils on a substrate coated with VCAM-1, to the left the clearance of the VCAM layer, to the right a phase contrast photo of the eosinophils.