Age-dependent fate and lineage restriction of single NG2 cells

TLDR

NG2-expressing glia appear during embryogenesis, expand perinatally, and persist throughout gray and white matter of the mature CNS. The study aimed to examine how NG2 cell fate changes over time by creating tamoxifen‑inducible NG2creER™BAC transgenic mice. Using these mice, the authors performed lineage tracing and live imaging of single NG2 cells in brain slices to follow division patterns and differentiation. They found that embryonic NG2 cells generate astrocytes, oligodendrocytes, and NG2 cells, whereas postnatal NG2 cells produce only oligodendrocytes or NG2 cells; at P2 most cells become oligodendrocytes, while at P60 most remain NG2 or form mixed clusters, and live imaging showed symmetric division followed by oligodendrocyte differentiation after 2–3 days.

Abstract

NG2-expressing glia (NG2 cells, polydendrocytes) appear in the embryonic brain, expand perinatally, and persist widely throughout the gray and white matter of the mature central nervous system. We have previously reported that NG2 cells generate oligodendrocytes in both gray and white matter and a subset of protoplasmic astrocytes in the gray matter of the ventral forebrain and spinal cord. To investigate the temporal changes in NG2 cell fate, we generated NG2creER™BAC transgenic mice, in which tamoxifen-inducible Cre is expressed in NG2 cells. Cre induction at embryonic day 16.5, postnatal day (P) 2, P30 and P60 in mice that were double transgenic for NG2creER™BAC and the Cre reporter revealed that NG2 cells in the postnatal brain generate only NG2 cells or oligodendrocytes, whereas NG2 cells in the embryonic brain generate protoplasmic astrocytes in the gray matter of the ventral forebrain in addition to oligodendrocytes and NG2 cells. Analysis of cell clusters from single NG2 cells revealed that more than 80% of the NG2 cells in the P2 brain give rise to clusters consisting exclusively of oligodendrocytes, whereas the majority of the NG2 cells in the P60 brain generate clusters that contain only NG2 cells or a mixture of oligodendrocytes and NG2 cells. Furthermore, live cell imaging of single NG2 cells from early postnatal brain slices revealed that NG2 cells initially divide symmetrically to produce two daughter NG2 cells and that differentiation into oligodendrocytes occurred after 2-3 days.