Vesicle trafficking and subcellular signal transduction in epithelial cells; gastric cancer.
Our laboratory studies a number of subjects that apply broadly to epithelial biology. We pursue three distinct programmatic areas. First, we are investigating the protein machinery required for the regulation of the recycling to the plasma membrane of receptors, ion transporters and ion channels. These studies focus on the ability of the Rab11 family of small GTPases (Rab11a, Rab11b and Rab25) to initiate and coordinate the assembly of multiprotein complexes regulating vesicle trafficking. Over the past several years, we have identified myosin Vb as the molecular motor involved in movement towards the plasma membrane. We have also identified a family of at least 8 other Rab11 family interacting proteins (Rab11-FIPs) that also participate in the regulation of plasma membrane recycling. Present investigations center on understanding the assembly of endogenous complexes, the regulation of recycling by novel protein kinase activities and the characterization of novel Rab11-FIP proteins. In addition, we have immunoisolated human parietal cell tubulovesicular recycling membrane vesicles and are performing a total proteomic analysis of the vesicle components. These proteomic studies are revealing unrecognized components of the membrane recycling pathways. Second, we have a long commitment to the study of cAMP-dependent protein kinase anchoring proteins (AKAP). Our present investigations focus on a multiply spliced family of 350-450 kDa AKAPs which we have designated AKAP350. We and others have found that AKAP350 is present at the Golgi apparatus and the centrosome and scaffolds a number of kinases and phosphatases including Type II A kinase, PKN, PKC-epsilon, CK1, phosphatase 1 and phosphatase 2a. In addition we have found that AKAP350 scaffolds Transforming acidic coiled-coil protein 3 and 4 at the centrosome, and a Chloride intracellular channel protein (CLIC5B) as well as cdc42-interacting protein 4 (CIP4) at the Golgi. Our present investigations center on both the investigation of the role of AKAP350 in regulating centrosome dynamics and the elucidation of AKAP350 function in regulating Golgi structure and function. Third, we have had a long-standing interest in gastritis, oxyntic atrophy and gastric cancer. We have identified a previously unrecognized metaplastic lineage associated with loss of gastric parietal cells. This lineage, designated Spasmolytic polypeptide expressing metaplasia (SPEM) is associated with gastric cancer in both humans as well as in mouse models of Helicobacter infection. Our present studies are using gene microarray and 2D-DIGE proteomics to analyze metaplastic lineages isoalted by laser capture microdissection. These studies seek to assemble a cohort of putative markers of the SPEM lineage. We will be using these markers to examine the relationship of SPEM with neoplastic transformation in humans.
We have had a long-standing interest in gastritis, oxyntic atrophy and gastric cancer. We have identified a previously unrecognized metaplastic lineage associated with loss of gastric parietal cells. This lineage, designated Spasmolytic polypeptide expressing metaplasia (SPEM) is associated with gastric cancer in both humans as well as in mouse models of Helicobacter infection. Our present studies are using gene microarray and laser capture microdissection to assemble a cohort of putative markers of the SPEM lineage. We will be using these markers to examine the relationship of SPEM with neoplastic transformation. In addition, we will be testing these new markers for their utility in identifying preneoplastic lesions in patients at risk for gastric cancer.
Postdoctoral Positions Available
1) Postdoctoral Associate Position Available
Research in an NIH-funded program to investigate the roles of A-kinase Anchoring Protein 350 (AKAP350), a large multi-functional scaffolding protein, in regulation of RNA trafficking. RNA trafficking studies seek to examine the role of AKAP350 and its associated proteins CCAR1 and caprin-1 in microtubule dependent RNA movement in cells under both baseline physiology and stress. Studies involve a range of cell biological techniques including subcellular fractionation, live cell microscopy and confocal fluorescence microscopy. Biochemical techniques include yeast two-hybrid approaches (both conventional and split ubiquitin), direct protein interaction studies and analysis of 3''''-untranslated region interactions with protein including live cell imaging of RNA movement. Studies will also seek to evaluate the role of AKAP350 in speciific tissues using a newly developed knockout mouse modelSalary commensurate with experience.
2) Postdoctoral Associate Positions Available
Research in an NIH-funded program to investigate the Roles of class V myosin motors in regulating membrane trafficking. Projects are focused on determining the structural basis of myosin Vb interaction with Rab proteins and their effectors using recombinant proteins co-expressed in bacteria as a substrate fo r structure determinations by crystallography and/or cryo-EM. Salary commensurate with experience.