Neurogenin

Neurogenin refers to two closely related basic helix-loop-helix transcription factors in vertebrates, Neurogenin1 (Neurog1) and Neurogenin2 (Neurog2). They belong to the proneural class of transcription factors and act as key regulators of neurogenesis during embryonic development.

Mechanism and action: Neurog1 and Neurog2 bind E-box motifs in DNA to activate gene programs that drive neuronal differentiation. They promote the expression of neuron-specific genes and tend to reduce progenitor proliferation as cells commit to a neuronal fate. Their activity is coordinated with other proneural factors and is modulated by signaling pathways such as Notch, which mediates lateral inhibition to balance progenitor maintenance with differentiation.

Expression patterns and roles: Neurog1 is expressed in neural progenitors across several regions, including the olfactory epithelium and certain cranial placodes, and is important for the development of olfactory and other sensory neurons. Neurog2 is expressed in developing cortical and other forebrain progenitors and supports the genesis of specific glutamatergic neurons, contributing to cortical neuron formation and regional neuronal identity.

Functional relationships: There is partial redundancy between Neurog1 and Neurog2 in many contexts, reflecting overlapping roles in promoting neuronal differentiation. Loss-of-function studies in model organisms show reduced neurogenesis or altered neuronal subtype formation, while overexpression can drive premature neuronal differentiation.

Clinical and research relevance: Neurogenin genes are central to vertebrate brain development and are widely studied in mammalian and other vertebrate models to understand how neural circuits are established, how neurogenesis is regulated, and how neuronal diversity is generated during development.