POLG mutations lead to abnormal mitochondrial remodeling during neural differentiation of human pluripotent stem cells via SIRT3/AMPK pathway inhibition

Cell Cycle. 2022 Jun;21(11):1178-1193. doi: 10.1080/15384101.2022.2044136. Epub 2022 Mar 17.

Abstract

We showed previously that POLG mutations cause major changes in mitochondrial function, including loss of mitochondrial respiratory chain (MRC) complex I, mitochondrial DNA (mtDNA) depletion and an abnormal NAD+/NADH ratio in both neural stem cells (NSCs) and astrocytes differentiated from induced pluripotent stem cells (iPSCs). In the current study, we looked at mitochondrial remodeling as stem cells transit pluripotency and during differentiation from NSCs to both dopaminergic (DA) neurons and astrocytes comparing the process in POLG-mutated and control stem cells. We saw that mitochondrial membrane potential (MMP), mitochondrial volume, ATP production and reactive oxygen species (ROS) changed in similar ways in POLG and control NSCs, but mtDNA replication, MRC complex I and NAD+ metabolism failed to remodel normally. In DA neurons differentiated from NSCs, we saw that POLG mutations caused failure to increase MMP and ATP production and blunted the increase in mtDNA and complex I. Interestingly, mitochondrial remodeling during astrocyte differentiation from NSCs was similar in both POLG-mutated and control NSCs. Further, we showed downregulation of the SIRT3/AMPK pathways in POLG-mutated cells, suggesting that POLG mutations lead to abnormal mitochondrial remodeling in early neural development due to the downregulation of these pathways. [Figure: see text].

Keywords: DA neurons; Mitochondrial remodeling; NSCs; POLG; astrocytes; iPSCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases
  • Adenosine Triphosphate
  • Astrocytes / cytology
  • Cell Differentiation
  • DNA Polymerase gamma* / genetics
  • DNA, Mitochondrial / genetics
  • Electron Transport Complex I / genetics
  • Humans
  • Mitochondria / genetics
  • Mutation / genetics
  • NAD
  • Neural Stem Cells / cytology
  • Pluripotent Stem Cells*
  • Sirtuin 3* / genetics

Substances

  • Adenosine Triphosphate
  • AMP-Activated Protein Kinases
  • DNA Polymerase gamma
  • DNA, Mitochondrial
  • Electron Transport Complex I
  • NAD
  • POLG protein, human
  • SIRT3 protein, human
  • Sirtuin 3

Grants and funding

This work was supported by funding from the Norwegian Research Council (project number: 229652), Rakel og Otto Kr.Bruuns legat. G.J.S was partly supported by the Norwegian Research Council through its Centres of Excellence funding scheme (project number: 262613). A.C was supported by the Chinese Government Funding: Department of Science & Technology of Shandong Province (project number: ZR2019ZD33 and 2020CXGC010903), the Special Foundation for Taishan Scholars (project number: ts20110814), Jinan Microecological Biomedicine Shandong Laboratory (project number: JNL-2022003A) and the China Scholarship Council (project number: the China scholarship council 201906220275). J.W was supported by the Special Foundation for Taishan Scholars (project number: ts20110814 and tshw201502056).