This is a competitive renew of a grant that has uncovered the essential roles of a heat shock protein (HSP) gp96 (also known as grp94 and HSP90b1) in chaperoning multiple TLRs in the endoplasmic reticulum. TLRs are critical sensors for pathogens in the initiation of innate immunity and for subsequent activation of adaptive immunity. Until recently, research in TLR biology has been focused primarily on downstream signaling events. It is increasingly appreciated that TLR biogenesis and trafficking are also tightly regulated to prevent inflammation and autoimmunity. My laboratory is at the forefront to address the function of gp96 using genetic approaches. We have discovered and published in the last funding period that: (i) gp96 is a master chaperone for both cell surface and intracellular TLRs;(ii) gp96 is not required for the assembly of immunoglobulin but it plays critical roles in the proper compartmentalization of B1 cells and marginal zone B cells due to its ability to also chaperone integrins;(iii) the Drosophila gp93 is the gp96 ortholog in that it can rescue the expression of both TLRs and integrins in gp96 KO murine cells;(iv) gp96 is critical for T and B lymphopoiesis but not myelopoiesis;(v) the folding of TLRs by gp96 is dependent on a substrate (TLR)-specific co-chaperone, CNPY3 (also known as PRAT4A). Unexpectedly, we have made two additional novel observations. First, gp96 plays critical roles in canonical Wnt signaling such that when gp96 is deleted from the gut, mice develop a profound and lethal enterocolitis. Second, when gp96 was selectively knocked down from macrophages, we observed a significant attenuation of inflammation-associated colon cancer and a concurrent reduction of IL23 and IL17. We thus hypothesize that gp96 provide a crucial link for multiple processes including inflammation, tissue homeostasis and cancer. We will tackle our hypothesis with the following three specific aims: (1) Determine the molecular mechanisms of gp96 in folding TLRs with specific focus on the roles of co-chaperones. (2) Establish the roles and mechanisms of gp96 in gut homeostasis. (3) Dissect the macrophage-intrinsic roles and mechanisms of gp96 in inflammation-associated colon cancer. Successful execution of our proposal shall significantly advance the field of chaperone biology, innate immunity, inflammation and tumor immunology.

Public Health Relevance

Proteins need to be folded into proper three-dimensional structure in order to have their biological function, which is often carried out by proteins called molecular chaperones. This project addresses the function and mechanism of one such chaperone that is particularly important in folding immune sensors to regulate inflammation and cancer. Knowledge learnt from this proposal should facilitate the development of novel drugs for the treatment of a variety of diseases such as sepsis, cancer and autoimmune disease.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Transplantation, Tolerance, and Tumor Immunology (TTT)
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Palker, Thomas J
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Medical University of South Carolina
Schools of Medicine
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Thaxton, Jessica E; Liu, Bei; Zheng, Pan et al. (2014) Deletion of CD24 impairs development of heat shock protein gp96-driven autoimmune disease through expansion of myeloid-derived suppressor cells. J Immunol 192:5679-86
Morales, Crystal; Rachidi, Saleh; Hong, Feng et al. (2014) Immune chaperone gp96 drives the contributions of macrophages to inflammatory colon tumorigenesis. Cancer Res 74:446-59
Zhang, Yongliang; Helke, Kristi L; Coelho, Sergio G et al. (2014) Essential role of the molecular chaperone gp96 in regulating melanogenesis. Pigment Cell Melanoma Res 27:82-9
Hua, Yunpeng; White-Gilbertson, Shai; Kellner, Joshua et al. (2013) Molecular chaperone gp96 is a novel therapeutic target of multiple myeloma. Clin Cancer Res 19:6242-51
Rachidi, Saleh M; Qin, Tingting; Sun, Shaoli et al. (2013) Molecular profiling of multiple human cancers defines an inflammatory cancer-associated molecular pattern and uncovers KPNA2 as a uniform poor prognostic cancer marker. PLoS One 8:e57911
Hong, Feng; Liu, Bei; Chiosis, Gabriela et al. (2013) *7 helix region of *I domain is crucial for integrin binding to endoplasmic reticulum chaperone gp96: a potential therapeutic target for cancer metastasis. J Biol Chem 288:18243-8
Wu, Shuang; Hong, Feng; Gewirth, Daniel et al. (2012) The molecular chaperone gp96/GRP94 interacts with Toll-like receptors and integrins via its C-terminal hydrophobic domain. J Biol Chem 287:6735-42
Wu, Shuang; Dole, Krystal; Hong, Feng et al. (2012) Chaperone gp96-independent inhibition of endotoxin response by chaperone-based peptide inhibitors. J Biol Chem 287:19896-903
Staron, Matthew; Wu, Shuang; Hong, Feng et al. (2011) Heat-shock protein gp96/grp94 is an essential chaperone for the platelet glycoprotein Ib-IX-V complex. Blood 117:7136-44
Audouard, Christophe; Le Masson, Florent; Charry, Colette et al. (2011) Oocyte-targeted deletion reveals that hsp90b1 is needed for the completion of first mitosis in mouse zygotes. PLoS One 6:e17109

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