One perspective
oRG are acutally astrocyte progenitors beacuse before the birth a lot of majority of astrocyte cells are expressing HOPX geens and share the gene signature to the oRGs.
But kriegstein claims that, when astrocyte matures, they turn down the oRG canonical genes, so the phenomenon above is just a transient event. oRG links the transition between RG and astrocyte.
Here is one interesting hyptoehsis related to such transition. oRG are enriched with three clusters gene: ECM production, EMT (believed to be the mechanism of oRG foramtion), stem cell maintenance. Also, the same three clusters is also be detected as the signature of glioblastoma multiforme (untreatable severe tumor). Astrocyte mutate and revert to the oRG fate, even in the adult brain those 'oRG' like cells heavily dividing and spread (since they jump and divide, MST). oRG may turn out to be the initial reason for the tumorgenesis? If it indeed takes the role of swith between RG and astrocytes.
Another thing is the adult genesis. In mouse hippocampus (thought to be major source for adult neurogenesis), they express high level of HOPX. Maybe they are actually the oRG like cells? But why human doesn't have adult neurogenesis despite the huge number of oRG cells during development? Still no answer.
