The role of SQSTM1 (p62) in mitochondrial function and clearance in human cortical neurons, 2021, Poon et al

Highlights

• SQSTM1 is dispensable for cortical neuron differentiation, modeled with human iPSCs
• Expression of bioenergetic genes is altered in human cortical neurons lacking SQSTM1
• Loss of SQSTM1 causes aberration in mitochondrial functionality
• SQSTM1 affects mitophagic processes but is not required for mitochondrial clearance

Summary
Sequestosome-1 (SQSTM1/p62) is involved in cellular processes such as autophagy and metabolic reprogramming. Mutations resulting in the loss of function of SQSTM1 lead to neurodegenerative diseases including frontotemporal dementia. The pathogenic mechanism that contributes to SQSTM1-related neurodegeneration has been linked to its role as an autophagy adaptor, but this is poorly understood, and its precise role in mitochondrial function and clearance remains to be clarified. Here, we assessed the importance of SQSTM1 in human induced pluripotent stem cell (iPSC)-derived cortical neurons through the knockout of SQSTM1. We show that SQSTM1 depletion causes altered mitochondrial gene expression and functionality, as well as autophagy flux, in iPSC-derived neurons. However, SQSTM1 is not essential for mitophagy despite having a significant impact on early PINK1-dependent mitophagy processes including PINK1 recruitment and phosphorylation of ubiquitin on depolarized mitochondria. These findings suggest that SQSTM1 is important for mitochondrial function rather than clearance.

Open access, https://www.cell.com/stem-cell-reports/fulltext/S2213-6711(21)00161-2