Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Christina Sisliyan - University of Southern California
Co-Author(s): Sarah Wong, University of Southern California, Los Angeles, CA; Laura Corrales-Diaz Pomatto, University of Southern California, Los Angeles, CA; John Tower, University of Southern California, Los Angeles, CA; Kelvin J.A. Davies, University of Southern California, Los Angeles, CA
The 20S proteasome is a stress-responsive enzyme that is up-regulated during oxidative stress. The 20S proteasome exhibits caspase-like (β1), trypsin-like (β2), and chymotrypsin-like (β5) proteolytic activity to degrade oxidized proteins and prevent the toxic aggregation and cross-linking of damaged proteins. The proteolytic activity of the 20S proteasome is a result of the interactions between the different subunits, β1, β2, and β5. One objective of this study is to explore the indirect impact of changes in β5 protein levels upon the other 20S proteasome subunits: β1 and β2. This study also investigates the adaptive role of the 20S proteasome’s β5 subunit in response to oxidative stress by measuring β5 amount and proteolytic activity in two fly strains: β5 RNAi and β5 overexpression strains. The goal of our study is to identify the role of the β5 subunit in an intact eukaryotic organism and determine how β5 modulation affects the overall 20S proteasome activity. We found that inhibiting the induction of the 20S proteasome β5 subunit led to a decline in the homeostatic adaptive response in female RNAi samples. Specifically, we found that females without the β5 subunit, lost the adaptive change in the catalytic activities of the 20S proteasome. The β5 RNAi also blocked the adaptive response in females following H2O2 pretreatment and subsequent challenge exposure. Conversely, overexpression of the β5 subunit promoted increased survival. Thus, the 20S proteasome β5 subunit is implicated in female adaptive survival. Males exhibit no adaptive change in the proteolytic activity, no adaptive increase in proteasome expression, and no adaptive response to H2O2, although they did adapt to redox cycling quinones (to be discussed elsewhere). Our exploration of the importance of the 20S proteasome β5 subunit in adaptive homeostasis, highlights the interconnection between signal transduction pathways and regulated gene expression in sexually divergent responses to oxidative stress.Sisliyan_Christina_ERN_2018_abstract.docx
Funder Acknowledgement(s): grant #DGE-1418060 of the USA National Science Foundation to LCDP; grant #ES003598 from the National Institute of Environmental Health Sciences of the US National Institutes of Health to KJAD; grant #AG052374 from the National Institute on Aging of the US National Institutes of Health to KJAD
Faculty Advisor: Kelvin J.A. Davies, firstname.lastname@example.org
Role: I measured the amount of the 20S proteasome by western blotting to evaluate protein expression. I also ran proteolytic activity assays to assess the activity of the 20S proteasome in two fly strains: β5 RNAi and direct β5 overexpression. I also recorded and analyzed kill curves via fly counts to measure adaptive survival in response to the sub-lethal dosages of oxidative stress.