Which molecule assists transcriptional activators that promote mitochondrial biogenesis in skeletal muscle following endurance training?

• A. NRF1
• B. AMPK
• C. PGC-1a
• D. TFAM

Answer: (C)

PGC-1α acts as the transcriptional coactivator that enables transcription factors to drive mitochondrial biogenesis in skeletal muscle after endurance exercise. It doesn’t bind DNA on its own, but it partners with factors like NRF-1 to ramp up the expression of nuclear-encoded mitochondrial genes, fueling the growth of the mitochondrial network. This coactivator also helps coordinate the rise of TFAM, which then promotes transcription and replication of mitochondrial DNA. While AMPK can activate PGC-1α, and NRF-1 is a transcription factor that relies on coactivators, the molecule that directly assists the transcriptional activators is PGC-1α.