No abstract

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disease causing neural cell degeneration and brain atrophy and is considered to be the most common form of dementia. We previously generated an induced pluripotent stem cell (iPSC) line from an AD patient carrying an A79V mutation in PSEN1 as an in vitro disease model. Here we generated a gene-corrected version from this hiPSC line by substituting the point mutation with the wild-type sequence. The reported A79V-GC-iPSCs line is a very useful resource in combination with the A79V-iPSC line in order to study pathological cellular phenotypes related to this particular mutation.

Human induced pluripotent stem cells (hiPSCs) hold great hopes for application in regenerative medicine due to their inherent capacity to self-renew and differentiate into cells from the three embryonic germ layers. For clinical applications, a large quantity of hiPSCs produced in standardized and scalable culture processes is required. Several groups, including ours, have developed methodologies for scaled-up hiPSC production in stirred bioreactors in chemically defined medium. In this study, we optimized the critical steps and factors that affect hiPSC expansion and yield in stirred-suspension cultures, including inoculation conditions, seeding density, aggregate size, agitation rate, and cell passaging method. After multiple passages in stirred-suspension bioreactors, hiPSCs remained pluripotent, karyotypically normal, and capable of differentiating into all three germ layers.

Mutations in the presenilin 1 (PSEN1) gene lead to the most aggressive form of familial Alzheimer's disease (AD). Human induced pluripotent stem cells (hiPSCs) derived from AD patients and subsequently differentiated can be used for disease modeling. We have previously generated a hiPSC line from a familial AD patient carrying a L150P point mutation in PSEN1. Here we used CRISPR/Cas9 gene editing to correct for the single base pair mutation. This gene-corrected line, L150P-GC-hiPSC, serves as an isogenic control to the mutant line for future investigation of mechanisms and cellular phenotypes altered by this specific PSEN1 mutation.

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.