Elevated mitochondrial metabolism in Down syndrome iPSCs reduces commitment to neuroectoderm

A key feature of Down syndrome (DS) is reduced neurogenesis. Here, we provide evidence that increased mitochondrial metabolism in DS stem cells reduces their ability to commit to neuroectoderm (NE), one of the earliest steps in the development of the nervous system. We show that mitochondria in induced pluripotent stem cells derived from individuals with DS (3S-iPSCs) have a higher membrane potential and increased capacity for calcium uptake via the mitochondrial calcium uniporter (MCU) compared to isogenic, euploid controls. Consequently, 3S-iPSCs proliferate faster and spend less time in G₁ of the cell cycle. This reduces the opportunity for growth of a primary cilium, an important developmental signaling hub. Inhibiting MCU or slowing proliferation of 3S-iPSCs is sufficient to increase ciliation and improve commitment to NE. In summary, we provide evidence that a mitochondria-to-cilia signaling axis important during the earliest steps of neurogenesis is dysregulated in DS iPSCs.