Dermal fibroblasts from long-lived Ames dwarf mice maintain their in vivo resistance to mitochondrial generated reactive oxygen species (ROS).

Activation of p38 MAPK by ROS involves dissociation of an inactive, reduced thioredoxin-ASK1 complex [(SH)(2)Trx-ASK1]. Release of ASK1 activates its kinase activity thus stimulating the p38 MAPK pathway. The level of p38 MAPK activity is, therefore, regulated by the balance of free vs. bound ASK1. Longevity of Ames dwarf mice is attributed to their resistance to oxidative stress. The levels of (SH)(2) Trx-ASK1 are more abundant in young and old dwarf mice compared to their age-matched controls suggesting that the levels of this complex may play a role in their resistance to oxidative stress. In these studies we demonstrate that dermal fibroblasts from these long-lived mice exhibit (a) higher levels of (SH)(2)Trx-ASK1 that correlate with their resistance to ROS generated by inhibitors of electron transport chain complexes CI (rotenone), CII (3-nitropropionic acid), CIII, (antimycin A), and H(2)O(2)-mediated activation of p38 MAPK, and (b) maintain their in vivo resistance to ROS generated by 3NPA. We propose that elevated levels of (SH)(2)Trx-ASK1 play a role in conferring resistance to mitochondrial generated oxidative stress and decreased endogenous ROS which are characteristics of longevity determination.