# Lateral Motor Column specific expression of Sonic Hedgehog contributes to maintenance and scaling of pMN progenitor cell populations during oligodendrogenesis

## TL;DR

This study shows that Sonic Hedgehog signaling from lateral motor column neurons helps maintain and scale OPC production in the spinal cord during development.

## Contribution

The study reveals a novel role for Sonic Hedgehog signaling in regulating OPC production based on MN development.

## Key findings

- Sonic Hedgehog signaling from lateral motor column neurons maintains a larger pMN domain at limb levels.
- Reduced Shh signaling leads to a significant decrease in OPC production in the spinal cord.
- OPC production at limb levels depends on the completion of MN production.

## Abstract

Motor neurons (MNs) and oligodendrocyte precursor cells (OPCs) emerge sequentially from the pMN precursor domain during spinal cord development. MNs diversify into muscle specific subtypes and settle in stereotypic locations in the ventral horns. In contrast, OPCs are mobile and appear to evenly populate the parenchyma. Whether earlier born MNs influence OPC production is controversial. We found that Sonic Hedgehog signaling emanating from nascent MNs of the lateral motor column is critical for maintaining a larger and more yielding pMN domain at limb levels compared to trunk levels during OPC production. Reduced Shh signaling resulted in unrecoverable diminishment of pMN domain based OPC production leaving the spinal cord impoverished of OPC. Our results suggest that production of OPC at limb levels is contingent on completion of MN production.