OLIG genes encode members of the basic helix-loop-helix (...

OLIG genes encode members of the basic helix-loop-helix (bHLH) family of transcription factors OLIG1, OLIG2, and OLIG3 (reviewed in Szu et al. 2023). OLIG genes are expressed in both the developing and mature central nervous system (CNS) and regulate cellular specification and differentiation (reviewed in Meijer et al. 2012, Szu et al. 2023). OLIG2 and SOX10 jointly define oligodendroglial identity and due to their continuous presence during development and in the differentiated state they shape the oligodendroglial regulatory network at all times (reviewed in Sock and Wegner 2021). Levels of OLIG1 and OLIG2 increase during the differentiation of NG2 cells, highly proliferative glial cells that can self-renew or differentiate into oligodendrocytes, promoting remyelination (reviewed in Li et al. 2017). OLIG1 and OLIG2 play important roles in the development and repair of oligodendrocytes, while NOTCH signaling negatively regulates oligodendrocyte differentiation (reviewed in Li et al. 2017).

Neurons and glial cells in the central nervous system (CNS) are generated from neuroepithelial cells in the ventricular zone that surrounds the embryonic neural tube (reviewed in Liu et al. 2021). OLIG family members are involved in the regulation of proliferation and distinct differentiation of neural precursors that leads to the generation of neuronal and glial cell subtypes (reviewed in Liu et al. 2021). Olig2-deficient mice exhibit large elimination of oligodendrocyte precursor cells and a decreased number of astrocyte progenitors in the dorsal cortex, whereas no reduction in the number of GABAergic neurons is observed (reviewed in Ono et al. 2009). OLIG1 and OLIG2 are thought to have played a seminal role during the evolution of the genetic programme leading to myelination in the CNS which, by increasing the conduction velocity of axons, allowed for increased body size, rapid movement, and a large and complex brain (reviewed in Li and Richardson 2008). Vertebrate homologs of the myelin basic protein (MBP) gene harbor OLIG1/OLIG2 and SOX10 binding sites (reviewed in Li and Richardson 2008). Besides being involved in the development of oligodendrocytes, OLIG2 is also implicated in the development of somatic motor neurons (reviewed in Rowitch et al. 2002).

OLIG2 overexpression is implicated in neurodevelopmental disorders such as Down syndrome (DS) and autism spectrum disorder (ASD) (reviewed in Szu et al. 2021). OLIG2 overexpression drives glioma proliferation and confers resistance to radiation and chemotherapy (reviewed in Szu et al. 2023). OLIG2 deletion or knockdown in glioblastoma reduces tumor growth and causes an oligodendrocytic to astrocytic phenotype shift, with PDGFRA downregulation and reciprocal EGFR signaling upregulation (reviewed in Kosty et al. 2019). Post-translational modifications regulate OLIG2 activity in glioma cell growth and invasive behaviors (reviewed in Kosty et al. 2017). Overexpression of OLIG2 in glioblastoma correlates with high expression of KDM6B, BRG1, DNMT1, and HDAC2, all associated with decreased survival glioblastoma patients (reviewed in Kapoor et al. 2025).

In addition to OLIG2 function in the developing cortex and cancer, OLIG2 is also reported to be important for glial scar formation after injury (reviewed in Ono et al. 2009). OLIG2 acts as a repressor of neurogenesis in cells reacting to brain injury (reviewed in Buffo et al. 2007).