HSP60 is required for stemness and proper differentiation of mouse embryonic stem cells

High levels of Heat Shock Protein 60 (HSP60) in mitochondria are required for self-renewal of mouse embryonic stem cells (mESCs). Myung-Kwan Han and colleagues at the National University Medical School in Jeonju, Korea, carried out a detailed comparison of these energy-producing organelles in mESCs and in a specialized, differentiated cell type: mouse embryonic fibroblasts (MEFs). Both the function and weight of mitochondria in mESCs were reduced compared to MEFs. Analyses of the mitochondrial protein composition in both cell types revealed significantly higher levels of HSP60 in mESCs. Depletion of HSP60 in mESCs not only prevented proliferation and self-renewal, but also led to cell death during differentiation. These findings highlight an important role for mitochondrial HSP60 in maintaining the ability of stem cells to self-renew and survive the differentiation process.