TGF-? drives the fibroinflammatory processes that leads to lung and airway fibrosis. The long-term goal of this project is to acquire a deep understanding of the regulation of TGF-? activity to develop new strategies and treatments for fibrosing lung disease. There are few effective therapies to treat chronic fibrosing and inflammatory diseases of the lung. The cytokine TGF-? is a central mediator of fibrosis and pathologic inflammation and is a potential therapeutic target in fibrosing lung disease. However, the practical utility of targeting TGF-? itself or its receptors is limited by risk of toxicities seen in rodents, primates and humans. More specific methods to target the fibroinflammatory effects of TGF-? are highly desirable. A promising method to more specifically target local effects of TGF-? is to target its ?activation? since it is always produced in a latent form (L-TGF-?) that must be activated in order to function. Another feature of L-TGF-? that could facilitate more specific targeting is that it is covalently bound to specific cell surfaces by GARP. L-TGF-? binding to the integrin ?v?8 is essential for TGF-? activation in vivo. For the ?v?8 activation mechanism, as well as all others, it has long been assumed that TGF-? must be released from LAP so that free TGF-? can diffuse and bind its receptors on target cells. Based on recent structural data obtained using single particle electron cryomicroscopy (cryo-EM), we have recently proposed a new model whereby ?v?8 can bind to L- TGF-? on cells presenting the L-TGF-?/GARP complex and induce signaling without release and diffusion of TGF-?. Here in three aims, we address three critical questions concerning this new model of L-TGF-? activation. (1) Which flexible domains of L-TGF-? of the ?v?8/L-TGF-?/GARP ternary complex shield TGF-? from its receptors? (2) Is flexibility of L-TGF-? induced by binding to ?v?8 necessary to mediate TGF-? activation? (3) Do TGF-? receptors (TGF-?Rs) bind to TGF-? within the ?v?8/L-TGF-?/GARP complex? To answer these questions, we will use cryo-EM to determine the structure of the ?v?8/L-TGF-?/GARP complex to determine how flexibility of L-TGF-? contributes to TGF-? activation, and finally we will capture the multimeric complex of TGF-?Rs with ?v?8/LTGF-?/GARP. These studies will improve mechanistic understanding of TGF-? activation and therapeutic targeting strategies to inhibit it.
There are currently few to no effective therapies to treat the airway and lung fibrosis in chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. The multifunctional cytokine transforming growth factor-? (TGF-?) is at the apex of a series of pathologic inflammatory and fibrotic events that culminate in fibroinflammatory pathology. The far-reaching goals of this project are to improve mechanistic understanding so that TGF-? can be effectively and selectively targeted to treat fibrosing and chronic inflammatory lung disease.
| Cormier, Anthony; Campbell, Melody G; Ito, Saburo et al. (2018) Cryo-EM structure of the ?v?8 integrin reveals a mechanism for stabilizing integrin extension. Nat Struct Mol Biol 25:698-704 |
| Takasaka, Naoki; Seed, Robert I; Cormier, Anthony et al. (2018) Integrin ?v?8-expressing tumor cells evade host immunity by regulating TGF-? activation in immune cells. JCI Insight 3: |
| Cheng, Yifan (2018) Single-particle cryo-EM-How did it get here and where will it go. Science 361:876-880 |
| Cheng, Yifan (2018) Membrane protein structural biology in the era of single particle cryo-EM. Curr Opin Struct Biol 52:58-63 |
| Palovcak, Eugene; Wang, Feng; Zheng, Shawn Q et al. (2018) A simple and robust procedure for preparing graphene-oxide cryo-EM grids. J Struct Biol 204:80-84 |
