HOPX regulates the development and lineage progression of human stem cell-derived outer radial glia-like cells.
TL;DR
Using CRISPR-Cas9 gene editing in human pluripotent stem cells, HOPX is identified as an important regulator of oRG-like cell maintenance and the neurogenic-gliogenic balance, providing insight into the molecular programs governing human neural progenitor expansion.
Abstract
Outer radial glia (oRG) are abundant in the human fetal cortex but rare in rodents, yet their molecular regulation remains poorly understood. Although the homeodomain-only protein X (HOPX) is a well-established oRG marker, its functional role in human cortical development remains undefined. Using CRISPR-Cas9 gene editing in human pluripotent stem cells, we show that HOPX loss impairs the expansion and lineage progression of oRG-like cells in two-dimensional neural cultures and three-dimensional cortical organoids. HOPX knockout precursors exhibit reduced proliferation, diminished neurogenesis, and premature differentiation toward astrocytic and oligodendrocytic lineages. HOPX-deficient organoids display reduced outer subventricular zone size, decreased neuronal output, and early gliogenesis. Mechanistically, HOPX loss impairs PI3K-mTOR signaling. Transcriptomic analysis identifies HOPX-regulated programs governing gliogenic competence, mTOR, and Wnt signaling. Together, these findings identify HOPX as an important regulator of oRG-like cell maintenance and the neurogenic-gliogenic balance, providing insight into the molecular programs governing human neural progenitor expansion.
