Exocytosis is important for the survival, growth and functions of all eukaryotic cells, and is centrally involved in many physiological processes ranging from neurotransmission to organogenesis. Exocytosis is mediated by transport, docking and fusion of secretory vesicles carrying cargos to the plasma membrane. The exocyst is an evolutionarily conserved octameric protein complex essential for exocytosis. Malfunction of the exocyst has been linked to diabetes, Autosomal Polycystic Kidney Diseases and cancer. We have recently solved the structure of the fully assembled exocyst complex by cryo-electron microscopy and identified two four-helix bundles, termed ?CorEx?, that potentially mediate the core assembly of the exocyst complex. In this proposal, we will first study the molecular interactions and high-resolution structure of the CorEx taking a multipronged approach that combines biochemistry, biophysics, crystallography, and microscopic imaging. We will also determine the function of the exocyst complex in SNARE assembly and membrane fusion using in vitro reconstituted liposome systems. Finally, we will examine the functional implication of a newly identified interaction between the exocyst and EHD proteins, which function in the generation of tubular vesicular carriers from the endosomal compartments. We will further examine the regulation of the exocyst-EHD interaction by RalA, a small GTPase that controls endosomal recycling to the plasma membrane in response to growth factor signaling. Our work will not only help elucidate the mechanisms of exocytosis at the molecular level, but also shed light to a number of diseases such as diabetes and cancer.
Exocytosis is implicated in many physiological processes such as embryogenesis, epithelial cell polarization, and neural transmission. The exocyst, an evolutionarily conserved octameric protein complex, plays an important role in exocytosis. Studying the basic function of the exocyst complex is essential for elucidating the molecular mechanisms of exocytosis and will lay the foundation for the understanding of many human diseases such as diabetes and cancer.
| Mei, Kunrong; Li, Yan; Wang, Shaoxiao et al. (2018) Cryo-EM structure of the exocyst complex. Nat Struct Mol Biol 25:139-146 |
| Chen, Gang; Huang, Alexander C; Zhang, Wei et al. (2018) Exosomal PD-L1 contributes to immunosuppression and is associated with anti-PD-1 response. Nature 560:382-386 |
| Zeng, Jingwen; Feng, Shanshan; Wu, Bin et al. (2017) Polarized Exocytosis. Cold Spring Harb Perspect Biol 9: |
| Zhu, Yueyao; Wu, Bin; Guo, Wei (2017) The role of Exo70 in exocytosis and beyond. Small GTPases :1-5 |
| Yue, Peng; Zhang, Yubo; Mei, Kunrong et al. (2017) Sec3 promotes the initial binary t-SNARE complex assembly and membrane fusion. Nat Commun 8:14236 |
| Zhang, Chunhua; Brown, Michelle Q; van de Ven, Wilhelmina et al. (2016) Endosidin2 targets conserved exocyst complex subunit EXO70 to inhibit exocytosis. Proc Natl Acad Sci U S A 113:E41-50 |
| Wu, Bin; Wang, Juanfei; Zhao, Yuting et al. (2015) Biochemical analysis of Rabin8, the guanine nucleotide exchange factor for Rab8. Methods Cell Biol 130:59-68 |
| Feng, Shanshan; Wu, Bin; Peränen, Johan et al. (2015) Kinetic activation of Rab8 guanine nucleotide exchange factor Rabin8 by Rab11. Methods Mol Biol 1298:99-106 |
| Wang, Juanfei; Ren, Jinqi; Wu, Bin et al. (2015) Activation of Rab8 guanine nucleotide exchange factor Rabin8 by ERK1/2 in response to EGF signaling. Proc Natl Acad Sci U S A 112:148-53 |
| Wu, Bin; Guo, Wei (2015) The Exocyst at a Glance. J Cell Sci 128:2957-64 |
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