The broad goal of this research project is to elucidate the mechanisms by which proteins and lipids in the endosome are packaged into transport carriers that bud from the endosome and ferry cargo to the Golgi apparatus and other organelles. These trafficking pathways, collectively termed 'endosomal retrograde transport,'are vital for cell physiology and homeostasis, metazoan development and they counter poorly understood processes that contribute to lysosomal storage diseases, cancer, Alzheimer's disease, and other diseases. In previous funding cycles we discovered that retrograde pathways are used to modulate the composition of the plasma membrane in response to environmental and nutritional cues, and we established roles for a soluble protein sorting complex called 'retromer'and three effectors of Phosphatidylinositol 3-kinase (PI3K) called sorting nexin (SNX) proteins. These components assemble on the endosome membrane where they capture and package cargo into budding transport carriers but the underlying mechanisms are unknown. With the principle cellular function of retromer now well established, the major challenge for the field is to elucidate the mechanisms by which it functions. Biochemical approaches will be used to dissect the mechanism of retromer assembly with cargo on the endosome membrane. These experiments will complemented with live cell imaging of retrograde transport that will place the assembly reactions in a physiological context. In recognition that the retromer sorting nexins are members of a much larger SNX protein family for which the functions of all but a few have been described, unbiased, proteome scale experiments will be used to elucidate the functions of each sorting nexin and to assess their specific contributions to cell physiology.
The cell contains a set of internal compartments (called organelles) that exchange molecules. The proposed research addresses how protein and lipid molecules are trafficked between organelles. Defects in these pathways lead to cancer, Alzheimer's and other neurological diseases, and cardiovascular disease.
|Ma, Mengxiao; Burd, Christopher G; Chi, Richard J (2016) Distinct complexes of yeast Snx4 family SNX-BARs mediate retrograde trafficking of Snc1 and Atg27. Traffic :|
|Deng, Yongqiang; Rivera-Molina, Felix E; Toomre, Derek K et al. (2016) Sphingomyelin is sorted at the trans Golgi network into a distinct class of secretory vesicle. Proc Natl Acad Sci U S A 113:6677-82|
|Popa, Andreea; Zhang, Wei; Harrison, Megan S et al. (2015) Direct binding of retromer to human papillomavirus type 16 minor capsid protein L2 mediates endosome exit during viral infection. PLoS Pathog 11:e1004699|
|Chi, Richard J; Harrison, Megan S; Burd, Christopher G (2015) Biogenesis of endosome-derived transport carriers. Cell Mol Life Sci 72:3441-55|
|DiMaio, Daniel; Burd, Christopher G; Goodner, Kylia (2015) Riding the R Train into the Cell. PLoS Pathog 11:e1005036|
|Chi, Richard J; Liu, Jingxuan; West, Matthew et al. (2014) Fission of SNX-BAR-coated endosomal retrograde transport carriers is promoted by the dynamin-related protein Vps1. J Cell Biol 204:793-806|
|Burd, Christopher; Cullen, Peter J (2014) Retromer: a master conductor of endosome sorting. Cold Spring Harb Perspect Biol 6:|
|Harrison, Megan S; Hung, Chia-Sui; Liu, Ting-ting et al. (2014) A mechanism for retromer endosomal coat complex assembly with cargo. Proc Natl Acad Sci U S A 111:267-72|
|Xu, Peng; Baldridge, Ryan D; Chi, Richard J et al. (2013) Phosphatidylserine flipping enhances membrane curvature and negative charge required for vesicular transport. J Cell Biol 202:875-86|
|Liu, Ting-Ting; Gomez, Timothy S; Sackey, Bridget K et al. (2012) Rab GTPase regulation of retromer-mediated cargo export during endosome maturation. Mol Biol Cell 23:2505-15|
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