OLIG1 and OLIG2 are expressed exclusively within the cent...

OLIG1 and OLIG2 are expressed exclusively within the central nervous system (CNS) and, for the most part, their expression appears coordinate in both space and time (reviewed in Meijer et al. 2012). OLIG2 expression is detected early during CNS development within the radial glia of the neural tube that ultimately give rise to motor neurons and oligodendrocytes (reviewed in Meijer et al. 2012). Later in development, OLIG2 is expressed in multipotent progenitor cells of the developing forebrain (reviewed in Meijer et al. 2012). In mice, Olig1 is first expressed in the dorsal portion and Olig2 in the ventral-most portion of the p3 progenitor domain of the ventral neural tube and they become confined to the domain that contains progenitors of motor neurons by embryonic days E10.5 and E9.5, respectively (reviewed in Meijer et al. 2012). Olig1 and Olig2 expression is sustained in mouse oligodendrocyte precursor cells and mature oligodendrocytes (reviewed in Meijer et al. 2012). Expression of Olig1 and Olig2 genes in developing mouse embryos precedes the earliest known markers of oligodendrocyte lineage (Lu et al. 2000). Ectopic expression of Olig1 in cultured rat cortical progenitors promotes their differentiation into oligodendrocyte precursors (Lu et al. 2000). Mouse Olig3 is expressed in the dorsal-most domain of the developing spinal cord but also in multiple tissue outside of the CNS (reviewed in Meijer et al. 2012).

In the developing spinal cord, OLIG1 and OLIG2 have been shown to be downstream targets of the ventralizing Sonic hedgehog (SHH) signaling (reviewed in Meijer et al. 2012). In the developing mouse brain, Olig1 and Olig2 genes are first expressed at the telencephalon-diencephalon border and adjacent to the floor plate, a known source of Shh (Lu et al. 2000). Shh is both necessary and sufficient for in vivo expression of Olig1 and Olig2 in the developing mouse brain (Lu et al. 2000). Downregulation of Olig1 and Olig2 expression in mouse motor neuron lineage cells correlates with increased expression of the homeobox protein Hb9, which may be related to Hb9-mediated upregulation of miR-17-3p (reviewed in Meijer et al. 2012). In glioblastoma tumors, which frequently overexpress OLIG2, miR-17-3p is downregulated (reviewed in Kapoor et al. 2025). BMP signaling regulates expression of mouse Olig3 (reviewed in Meijer et al. 2012).