Functions of molecular chaperones in modulating cell surface receptors and secreted proteins
Chaperones, BiP, GRP94, HSP90, calreticulin, Amyloid, Light Chain, Heavy Chain, B Cell Receptor, Insulin-like growth factors, Peptide, Stress Response, Development.
Description of Research
Communication among cells through secreted ligands and their receptors underlies the organization of tissues. The proper expression of receptors and secretion of protein ligands are dependent on accessory proteins, molecular chaperones, which regulate their biosynthesis and minimize their misfolding. Our work focuses on the molecular chaperones in the endoplasmic reticulum, where membrane and secreted proteins are synthesized.
BiP is a peptide binding protein that controls folding of antigen receptors by binding selectively to some peptides in the newly synthesized proteins. Because of this ability, BiP provides an important quality control function in screening somatically mutated molecules. One project in the lab concerns how BiP recognizes normal Ig sequences and distinguishes them from aggregation-prone somatic mutants. A second project examines the use of BiP as an inhibitor of the pathologic polymerization of antibodies into amyloid fibers.
GRP94 has a different mode of action and therefore biological activity. Although it binds peptides, its specificity is different from BiP. We use combinatorial genetic and biochemical techniques to characterize its preferred binder peptides and identify the features that it recognizes in client proteins. We developed the first cell-based assay for the chaperone function of GRP94, relying on the discovery that GRP94 is needed for production of Insulin-like growth factors, which are needed for cultured cells to cope with stress. We assay variants of GRP94 by expressing them in stressed chaperone-deficient cells. The more functional the variant chaperone, the higher the level of growth factor that is produced and the higher the survival of the cells under stress. This assay enables us to dissect the biochemical mode of action of GRP94.
Another project explores the GRP94-IGF axis in muscle physiology, using mice with targeted deletion of GRP94 in skeletal muscle. We use this model to understand what are the major client proteins of the chaperone in myocytes and to ask how modulation of GRP94 expression affect the recovery of muscle from injury.
A third project utilizes proteomic approaches to identify the interactions among ER chaperones as well as their co-factors, to understand the dynamic nature of the chaperone network and the changes in it during physiological ER stress.
1. Structure-function analysis of chaperones using cell-based assays
2. Analysis of GRP94-deficient mice
3. Proteomic analyses of chaperone-deficient cells
4. Analysis of an amyloid LC-expressing transgenic mouse
5. The GRP94-IGF axis in growth control
6. Genetic analysis of chaperone action in C. elegans
Ostrovsky, O - Research Associate
Eletto, D - Postdoctoral Fellow
Dersh, D - Graduate Student
James, J - Technician
Ostrovsky O, Makarewich CA, Snapp EL, Argon Y.: An essential role for ATP binding and hydrolysis in the chaperone activity of GRP94 in cells. Proc. Nat. Acad. Sci 106(28): 11600-5, 2009 PMCID: PMC2710619.
Ostrovsky O, Ahmed NT, Argon Y: The chaperone activity of GRP94 toward insulin-like growth factor II is necessary for the stress response to serum deprivation. Mol. Biol. Cell 20(6): 1855-64, 2009 PMCID: PMC2655248.
Biswas C, Ostrovsky O, Makarewich CA, Wanderling S, Gidalevitz T, Argon Y.: The peptide binding activity of GRP94 is regulated by calcium Biochem. J 405(2): 233-41, 2007.
Wanderling S, Simen BB, Ostrovsky O, Ahmed NT, Vogen SM, Gidalevitz T, Argon Y.: GRP94 is essential for mesoderm induction and muscle development because it regulates IGF-II. Mol. Biol. Cell 18(10): 3764-75, 2007.
Elkabetz Y, Argon Y, Bar-Nun S.: Cysteines in the CH1 domain underlie retention of unassembled Ig heavy chains. J. Biol. Chem 280(15): 14402-12, 2005.
Davis PD, Raffen R, Dul LJ, Vogen MS, Williamson KE, Stevens JF, Argon Y.: Inhibition of amyloid fiber assembly by both BiP and its target peptide. Immunity 13(4): 433-442, 2000.
Dul JL1, Davis DP, Williamson EK, Stevens FJ, Argon Y.: Hsp70 and antifibrillogenic peptides promote degradation and inhibit intracellular aggregation of amyloidogenic light chains. J. Cell. Biol 152(4): 705-16, 2001.
Davis DP1, Gallo G, Vogen SM, Dul JL, Sciarretta KL, Kumar A, Raffen R, Stevens FJ, Argon Y.: Both the environment and somatic mutations govern the aggregation pathway of pathogenic immunoglobulin light chain. J. Mol. Biol 313(5): 1023-1036, 2001.
Vogen S, Gidalevitz T, Biswas C, Simen BB, Stein E, Gulmen F, Argon Y.: Radicicol-sensitive peptide binding to the N-terminal portion of GRP94. J. Biol. Chem 277(43): 40742-50, 2002.
Gidalevitz T, Biswas C, Ding H, Schneidman-Duhovny D, Wolfson HJ, Stevens F, Radford S, Argon Y.: Identification of the N-terminal peptide binding site of glucose-regulated protein 94. J. Biol. Chem. 279(16): 16543-52, 2004.
back to top
Last updated: 06/02/2021
The Trustees of the University of Pennsylvania