(886.2) The combination of NRF1 and Nrf2 activators in myoblasts stimulate mechanisms of proteostasis without changes in mitochondrial respiration

Poster Board Number: E311

Maureen Walsh (Colorado State University), Qian Zhang (Colorado State University), Robert Musci (Loyola Marymount University), Karyn Hamilton (Colorado State University, Colorado State University)

Persistent oxidative stress contributes to hallmarks of aging, including impaired proteostasis and mitochondrial dysfunction, while acute oxidative challenges resolved swiftly contribute to beneficial adaptations. Adaptive homeostasis is where acute exposures to sub-toxic stimuli kindle transient expansion of responses necessary to reestablish homeostasis. Elucidating mechanisms underlying adaptive homeostasis will provide novel targets for healthspan extension. Nrf2 is a key regulator of cytoprotective gene transcription for redox homeostasis; NRF1 is a transcription factor that regulates expression of genes necessary for mitochondrial function. Regulation of both is compromised with advancing age. We hypothesized that NRF1 (NRF1a) and Nrf2 (Nrf2a) activators might improve adaptive homeostasis in response to an oxidative challenge by promoting mitochondrial proteome maintenance and function in C2C12 myoblasts. Using deuterium stable isotope tracing, we assessed protein synthesis over a 16-hr treatment with a CON (DMSO), NRF1a, Nrf2a, or both, with and without a hydrogen peroxide (H2O2) stress. We assessed mitochondrial function using high-resolution respirometry. Co-treatment of NRF1a and Nrf2a under H2O2 stress favored proteostatic maintenance (plt;0.05) through maintained protein synthesis (pgt;0.05), but a decrease in cell proliferation (plt;0.05). H2O2 stress significantly decreased mitochondrial maximal respiration, but this decrease was not rescued by NRF1a/Nrf2a co-treatment indicating the same ATP availability. Interestingly, there were no differences in submaximal ADP stimulated respiration or ADP sensitivity between CON, H2O2, or the NRF1a/Nrf2a co-treatment (pgt;0.05). Further, there were no differences in endogenous redox capacity or mitochondrial protein content between treatment groups. These results suggest that simultaneously targeting NRF1 and Nrf2 may be a viable approach for reestablishing mitochondrial protein homeostasis following a stress, but that this adaptation may not improve respiratory capacity.

Support or Funding Information

LifeVantage Corporation and American College of Sports Medicine NASA Space Physiology Award