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Human Mpv17-like protein with a mitigating effect on mtDNA damage is involved in cAMP/PKA signaling in the

Reiko Iida1, Misuzu Ueki2, Toshihiro Yasuda3

  • 1Life Science Unit, School of Medical Sciences, University of Fukui, Fukui 910-1193, Japan; Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.

Biochimica Et Biophysica Acta. Molecular Cell Research
|July 5, 2020
PubMed

Insights

Human Mpv17-like protein (M-LPH) may function as a novel phosphodiesterase (PDE) in mitochondria. M-LPH deficiency disrupts cAMP/PKA signaling, impacting mitochondrial DNA maintenance and potentially leading to dysfunction.

Area of Science:

  • Mitochondrial biology
  • Molecular cell biology
  • Biochemistry

Background:

  • Human Mpv17-like protein (M-LPH) is implicated in mitigating mitochondrial dysfunction from DNA damage.
  • Mitochondrial dysfunction involves mitochondrial DNA (mtDNA) damage and reduced levels of transcription factor A (TFAM).
  • TFAM reduction is linked to increased phosphorylation, suggesting involvement of the cAMP/protein kinase A (PKA) pathway.

Purpose of the Study:

  • To investigate the role of M-LPH in the cAMP/PKA signaling pathway within HepG2 cells.
  • To determine if M-LPH possesses phosphodiesterase (PDE) activity.
  • To elucidate the mechanism by which M-LPH influences TFAM stability and mitochondrial function.

Main Methods:

  • Generating M-LPH-knockout (M-LPH-KO) HepG2 cells.
  • Measuring mitochondrial cAMP levels and cellular PDE activity.
  • Assessing TFAM protein levels and phosphorylation status.
  • Performing in vitro PDE activity assays with synthesized M-LPH.
  • Analyzing PKA-dependent phosphorylation of mitochondrial proteins.

Main Results:

  • M-LPH-KO HepG2 cells exhibited increased mitochondrial cAMP and decreased total cellular PDE activity.
  • In vitro assays demonstrated that synthesized M-LPH possesses PDE activity, inhibited by IBMX.
  • M-LPH-KO led to enhanced PKA-dependent phosphorylation of several mitochondrial proteins.
  • These changes correlate with reduced TFAM protein levels and increased mtDNA damage.

Conclusions:

  • M-LPH may function as a novel mitochondrial phosphodiesterase (PDE) regulating the cAMP/PKA pathway.
  • M-LPH's PDE activity influences TFAM phosphorylation and stability, crucial for mtDNA maintenance.
  • M-LPH deficiency disrupts mitochondrial homeostasis, highlighting its role in preventing mitochondrial dysfunction.
Keywords:
Cyclic nucleotide phosphodiesteraseMitochondrial matrixMpv17-like proteincAMP/PKA signaling

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