Mitohormesis in muscle cells: a morphological, molecular, and proteomic approach

Low-level oxidative stress induces an adaptive response commonly defined as hormesis; this type of stress is often related to reactive oxygen species (ROS) originating from the mitochondrial respiratory chain (mitochondrial hormesis or mitohormesis). The accumulation of transient low doses of ROS either through chronic physical activity or caloric restriction influences signaling from the mitochondrial compartment to the cell, reduces glucose metabolism, induces mitochondrial metabolism, increases stress resistance and ultimately, increases lifespan. Mitochondrial formation of presumably harmful levels (chronic and/or excessive) of ROS within skeletal muscle has been observed in insulin resistance of obese subjects, type 2 diabetes mellitus, as well as in impaired muscle function associated with normal aging. Advances in mitochondrial bioimaging combined with mitochondrial biochemistry and proteome research have broadened our knowledge of specific cellular signaling and other related functions of the mitochondrial behavior. In this review, we describe mitochondrial remodeling in response to different degrees of oxidative insults induced in vitro in myocytes and in vivo in skeletal muscle, focusing on the potential application of a combined morphological and biochemical approach. The use of such technologies could yield benefits for our overall understanding of physiology for biotechnological research related to drug design, physical activity prescription and significant lifestyle changes.