Cell biology, organelle biogenesis and intracellular trafficking as a basis of infectious disease
I. Phagosomal biogenesis and maturation is an area of dual biological significance: 1) It is a fundamental cell biology phenomenon dependent upon intracellular trafficking of membranes, membrane proteins, and lumenal cargo proteins. 2) Phagocytosis of the majority of microorganisms by immune phagocytic cells results in the control of the microbe and processing of its antigens for presentation; in contrast, intracellular pathogens such as Mycobacterium tuberculosis have evolved mechanisms of interfering with phagosomal maturation into phagolysosomes. Our interests are focusing on both aspects of phagosomal biogenesis related to fundamental trafficking processes and pathogenesis of infectious disease. We have recently developed technologies to study phagosomal maturation based on fluorescence microscopy using Green Fluorescent Protein (GFP), and biochemical analyses using purified phagosomes and other intracellular organelles. We have recently linked the arrest of Mycobacterium tuberculosis phagosome maturation to alterations in Rabs, small GTP-binding proteins that regulate membrane trafficking in eucaryotic cells. We are currently narrowing down the precise target for this block by investigating additional factors controlling membrane fusion and trafficking: Rab effectors, PI3 kinases, and SNAREs. Also, we are identifying bacterial products (toxins) which interfere with these targets.
II. Cystic Fibrosis (CF) is the most common inheritable lethal disease among Caucasians. It is caused by mutations in a gene encoding CFTR, a chloride channel that has additional, pleiotropic regulatory effects on other ion conductances in epithelial cells. CF is lethal due to continuous decline in respiratory function caused by chronic infections and inflammation. Despite several concurrent proposals, there is presently no consensus on how the defect in CFTR leads to the pathology in the CF lung. We have recently found, using a ratiometric pH-sensitive GFP variant, that intracellular organelles are hyperacidified in CF lung epithelial cells. We are now investigating the mechanism of hyperacidification and the consequences on protein glycosylation and trafficking in CF cells. We believe that these changes lead to the chronic infections and inflammation in the CF lung.
Fratti, R. A., J. M. BackerJ. Gruenberg, S. Corvera, and V. Deretic. 2001. Role of phosphatidylinositol 3-kinase and Rab5 effectors in phagosomal biogenesis and mycobacterial phagosome maturation arrest. J. Cell Biol. 154:631-644.
Poschet, J.F., J. C. Boucher, L. E. Tatterson, J. Skidmore, R. W. Van Dyke and V. Deretic. 2001. Molecular basis for defective glycosylation and Pseudomonas pathogenesis in cystic fibrosis lung. Proc. Natl. Acad. Sci. USA 98:13972-13977.
Poschet, J. F., J. Skidmore, J. C. Boucher, R. W. Van Dyke and V. Deretic. 2002. Hyperacidification of cellubrevin endocytic compartments and defective endosomal recycling in cystic fibrosis respiratory epithelial cells. J. Biol. Chem, Papers in press on JBC web site; accesion # 11809765.
Fratti, R., J. Chua, and V. Deretic. 2002. Cellubrevin alterations and mycobacterial phagosome maturation arrest. J. Biol. Chem., Papers in press on JBC web site; accession # 11825909.
Dr. Vojo Deretic
Professor
BMSB 353
University of New Mexico Health Sciences Center
915 Camino de Salud, NE
Albuquerque, NM 87131
U.S.A.
(505) 272-0291
FAX 505-272-5309
