Mitophagy is Required for Proper Mitochondrial Network Remodeling during Cardiac Progenitor Cell Differentiation

Abstract

Cell based therapies represent a very promising strategy to repair and regenerate the injured heart to prevent progression to heart failure. To date, cell based therapies have had limited success due to a lack of survival and retention of the infused cells. Therefore, it is important to increase our understanding of the biology of these cells and utilize this information to enhance their survival and function in the unfavorable environment of the injured heart. Mitochondria are critical for progenitor cell function and survival. Here we demonstrate the importance of mitochondrial autophagy, or mitophagy, in the differentiation process in adult cardiac progenitor cells (CPCs). We found that mitophagy is rapidly induced upon initiation of differentiation in CPCs. We also found that mitophagy was mediated by the mitophagy receptors pathway, rather than the PINK1/Parkin pathway. Mitophagy receptors Nix and Fundc1, but not Bnip3, were upregulated during differentiation. Mitophagy mediated by Nix and Fundc1 was not involved in regulating progenitor cell fate determination, mitochondrial biogenesis, or reprogramming. Instead, mitophagy facilitated the CPCs to undergo proper mitochondrial network reorganization during differentiation. Abrogating Nix/Fundc1‐mediated mitophagy during differentiation led to mitochondrial fragmentation and failure to form an interconnected mitochondrial network. It also led to increased susceptibility to hydrogen peroxide mediated cell death during differentiation. Finally, aging is associated with accumulation of mtDNA mutations in cells and we found that acquiring mtDNA mutations selectively disrupted the differentiation‐activated mitophagy program in CPCs. These findings demonstrate the importance of Nix/Fundc1‐mediated mitophagy as a critical regulator of mitochondrial network formation in differentiating progenitor cells, as well as the consequences of accumulating mtDNA mutations.Support or Funding InformationA.B. Gustafsson is supported by an AHA Established Investigator Award, and by NIH R21AG052280, R01HL087023, R01HL132300 and P01HL085577. M.A. Lampert is supported by the UCSD Graduate Training Program in Cellular and Molecular Pharmacology grant T32GM007752. A.M. Orogo is supported in part by the UCSD Graduate Training Program in Cellular and Molecular Pharmacology through an institutional training grant from the National Institute of General Medical Sciences T32GM007752, and National Institutes of Health NRSA Predoctoral Fellowship F31HL123309.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.