Mitophagy-driven mitochondrial rejuvenation regulates stem cell fate

Area of Science:

• Cell Biology
• Stem Cell Biology
• Mitochondrial Biology

Background:

• Selective mitochondrial autophagy, or mitophagy, is essential for maintaining cellular homeostasis and function.
• PTEN-induced putative kinase 1 (PINK1) is a key regulator of mitophagy, involved in clearing damaged mitochondria.
• The precise role of mitophagy in sustaining stem cell pluripotency and reprogramming efficiency remains incompletely understood.

Purpose of the Study:

• To investigate the causal role of PINK1-dependent mitophagy in controlling cell-fate plasticity and pluripotency maintenance.
• To evaluate the impact of mitophagy deficiency on induced pluripotent stem cell (iPSC) reprogramming and cellular characteristics.
• To elucidate the bioenergetic and metabolic consequences of impaired mitophagy in iPSCs.

Main Methods:

• Utilized embryonic fibroblasts from PINK1 gene-knockout (KO) mice to assess mitophagy's role.
• Performed induced pluripotent stem cell (iPSC) reprogramming experiments with mitophagy-deficient cells.
• Analyzed mitochondrial morphology, pluripotency marker expression, cellular bioenergetics, and targeted metabolomics (glycolysis and TCA cycle metabolites).
• Assessed teratoma-initiating capacity and in vivo differentiation potential of mitophagy-deficient iPSCs.

Main Results:

• Loss of PINK1-dependent mitophagy significantly reduced the speed and efficiency of iPSC reprogramming.
• Mitophagy-deficient iPSCs exhibited unstable colonies with a tendency for spontaneous differentiation and heterogeneous cell populations.
• Impaired mitophagy led to attenuated glycolysis, altered TCA cycle metabolites (notably decreased α-ketoglutarate), and a mixture of mature and immature mitochondria.
• Mitophagy-deficient iPSCs showed reduced teratoma-forming capacity but retained pluripotency and in vivo differentiation potential.

Conclusions:

• The PINK1-dependent mitophagy pathway acts as a critical mitochondrial regulator for efficient and high-quality somatic cell reprogramming.
• Mitophagy-driven mitochondrial rejuvenation is likely involved in suppressing iPSC differentiation by remodeling bioenergetics and metabolomics.
• These findings offer novel insights into mitophagy's influence on stem cell fate decisions relevant to tissue regeneration, aging, and regenerative medicine.