Overexpression of PKM2 promotes mitochondrial fusion through attenuated p53 stability

Area of Science:

• Cell Biology
• Mitochondrial Biology
• Cancer Metabolism

Background:

• Pyruvate kinase M2 (PKM2) is known to promote the Warburg effect in cancer.
• The impact of PKM2 on mitochondrial function remains largely unexplored.

Purpose of the Study:

• To investigate the role of PKM2 in regulating mitochondrial function.
• To elucidate the molecular mechanisms linking PKM2 to mitochondrial dynamics and cellular metabolism.

Main Methods:

• Overexpression and knockdown of PKM2 in cellular models.
• Analysis of mitochondrial morphology, ATP production, mtDNA copy number, and electron transport chain (ETC) complex expression.
• Western blotting and co-immunoprecipitation to assess protein levels and interactions (p53, MDM2, Drp1).
• Analysis of clinical samples to confirm PKM2-Drp1 relationship.

Main Results:

• PKM2 overexpression led to mitochondrial fusion, decreased ATP production, elevated mtDNA copy number, and reduced ETC complex expression.
• PKM2 overexpression suppressed p53 levels and half-life by promoting MDM2-mediated ubiquitination.
• PKM2 directly binds to p53 and MDM2, with dimeric PKM2 showing stronger suppression of p53.
• A negative correlation between PKM2 and Drp1 expression was observed in clinical samples.

Conclusions:

• PKM2 inhibits mitochondrial function through the downregulation of the p53-Drp1 axis.
• This study reveals a novel mechanism connecting PKM2 to mitochondrial dysfunction.
• The PKM2-p53-Drp1 pathway represents a potential therapeutic target for diseases involving mitochondrial abnormalities.