ERK-mediated phosphorylation of TFAM downregulates mitochondrial transcription: implications for Parkinson's disease

Area of Science:

• Cellular biology
• Molecular biology
• Neuroscience

Background:

• Mitochondrial transcription factor A (TFAM) is crucial for mitochondrial biogenesis.
• Extracellular signal-regulated protein kinases (ERK1/2) signaling can downregulate mitochondrial function.
• The complex I inhibitor 1-methyl-4-phenylpyridinium (MPP+) impairs mitochondrial activity.

Purpose of the Study:

• To elucidate the mechanism by which ERK1/2 affects TFAM.
• To identify specific phosphorylation sites on TFAM regulated by ERK1/2.
• To investigate the functional consequences of TFAM phosphorylation on mitochondrial transcription and respiration.

Main Methods:

• Mass spectrometry was used to identify ERK1/2-dependent phosphorylation sites on TFAM.
• Site-directed mutagenesis was employed to mimic TFAM phosphorylation at serine 177.
• The effects of wild-type and mutant TFAM on mitochondrial transcription, DNA binding, and respiratory function were assessed.

Main Results:

• ERK1/2-dependent phosphorylation sites on TFAM were identified.
• Mutation of TFAM at serine 177 to mimic phosphorylation decreased TFAM binding to the light strand promoter.
• Phosphorylated TFAM suppressed mitochondrial transcription and did not rescue MPP+-induced deficits in respiratory function.

Conclusions:

• ERK1/2 directly phosphorylates TFAM at serine 177.
• TFAM phosphorylation by ERK1/2 is a novel mechanism regulating mitochondrial biogenesis and function.
• This pathway is implicated in cellular responses to mitochondrial stress, such as that induced by MPP+.