Deciphering the Molecular Basis for ShcA ROS Production and Function
Franklin A. Hays1* and Jennifer M. Johnson1
1Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
Src homologous-collagen homologue family A, or ShcA, proteins mediate phosphotyrosine-dependent signaling complex assembly at the cell membrane1. The p66Shc ShcA isoform is also associated with producing ~30% of mitochondrial-derived reactive oxygen species (ROS) in mammalian cells2 and is directly implicated in human disease onset and progression3,4. Previous studies suggest that p66Shc ROS activity is dependent upon functional interactions with cytochrome c (cyt c) and respiring mitochondria. These interactions were thought to be mediated by the N-terminal collagen homology 2 (CH2) and cyt c binding (CB) domains of human p66Shc. However, it remains unclear how this protein functions at the molecular level2 and no full-length structures have been determined. Using purified protein and in vitro assays, we are focused on defining the molecular basis for ShcA function - inclusive of enzymatic ROS activity, structure, and deciphering functional interactions with, and cellular implications of, the mitochondrial electron transport chain. Current results have redefined the type of ROS produced by p66Shc, molecular basis for enzymatic function, and the functional relationship between the ETC and p66Shc-mediated electron flow and function. Our results provide fundamental insights into ShcA function as a molecular rheostat that drives either pro-survival or pro-apoptotic response pathways. Developing a mechanistic model for ShcA enzymatic function is relevant to the downstream development of ShcA isoform-specific catalytic antioxidants for treating human disease.
1 Zheng, Y. et al. Nature 499, 166-171, doi:10.1038/nature12308 (2013).
2 Giorgio, M. et al. Cell 122, 221-233, doi:10.1016/j.cell.2005.05.011 (2005).
3 Fadini, G. P. et al. Diabetes 59, 2306-2314, doi:10.2337/db09-1727 (2010).
4 Spescha, R. D. et al. Eur Heart J, doi:10.1093/eurheartj/ehv140 (2015).
Research supported by the National Institute of General Medical Sciences of the National Institutes of Health under grant number R01GM118599.