Regulation of hypoxia-inducible genes by PGC-1 alpha.

Atmospheric oxygen appeared approximately 2.3 billion years ago and sustains most complex life on earth. As mitochondria evolved to harness the energy in oxygen, systems developed to sense and respond to local oxygen concentrations and metabolic conditions. For more than a decade, research has focused on hypoxia-inducible factor 1 (HIF1), a key component of the eukaryotic oxygen-response system. Recently, evidence for other systems has also surfaced. One of these systems involves the PGC-1 alpha coactivator, a powerful transcriptional regulator of mitochondria and oxidative metabolic programs. This brief review will focus on this burgeoning role for PGC-1 alpha and will highlight the many questions that remain unanswered.