Transcription factor that binds a palindromic (canonical) core consensus DNA sequence 5'-CANNTG- 3' known as an E-box element, possibly as a heterodimer with other bHLH proteins (By similarity). Regulates endothelial cell proliferation, migration and tube-like structures formation (By similarity). Modulates endothelial cell differentiation through NOS3 (By similarity). May be implicated in specification and differentiation of neuronal cell lineages in the brain (PubMed:11733035). May participate in kidney development and may be involved in podocyte differentiation (PubMed:16937370). During early embryonic development is involved in tissue-specific differentiation processes that are dependent on class II bHLH factors and namely modulates the differentiation program initiated by the pro-endocrine factor NEUROG3 (PubMed:18560595). During myogenesis, may play a role during the transition of myoblasts from the proliferative phase to the differentiation phase (PubMed:24186058). Positively regulates HAMP transcription in two ways, firstly by acting directly on the HAMP promoter via E-boxes binding and indirectly through increased phosphorylation of SMAD protein complex (By similarity). Repress NEUROG3-dependent gene activation in a gene-specific manner through at least two mechanisms; requires only either the sequestering of a general partner such as TCF3 through heterodimerization, either also requires binding of the bHLH domain to DNA via a basic motif (PubMed:23938248). Efficient DNA binding requires dimerization with another bHLH protein. Interacts with NEUROG3 AND NEUROD1. Interacts with ZFPM2; mediates indirect interaction with GATA4. Forms a heterodimer with TCF3; repress transcription of TCF3 and TCF3/NEUROG3 dimer-induced transactivation of E box-dependent promoters. Expressed by subsets of mature neurons (PubMed:11733035). Expressed in kidney (podocytes) (PubMed:16937370). Expression is restricted to the atria, lung mesenchyme, and vascular smooth muscle (PubMed:23836893). Expressed at high levels at 8.5 dpc and its expression level gradually decreases during embryogenesis. At 12.5 dpc, is expressed throughout the developing nervous system. It is expressed in both the ventricular zone and the mantle layer of the developing brain. At 14.5 dpc, expressed in the cortical plate as well as in other regions of the brain. Also expressed at a high level in the spinal cord and dorsal root ganglia. Expressed by almost all cells in the spinal cord and dorsal root ganglia at this stage. At later stages, expression is gradually restricted to several regions such as the hippocampus, cerebellum and retina. In the hippocampus, a high level of expression continues during embryogenesis until adulthood. Expressed in the CA1-CA3 regions and the dentate gyrus. At 18.5 dpc, expressed in cerebellum by Purkinje cells and granule cell precursors in the external granular layer (EGL). By postnatal day 4, expressed by aligned Purkinje cells and by the EGL and internal granular layer (IGL) cells. In the adult cerebellum, expressed at a high level by Purkinje cells and weakly by granule cells in the IGL. In developing retina, expressed in both the ganglion cell layer and the ventricular zone at 11.5 dpc and 17.5 dpc. Expression becomes very weak in the adult retina. Early in metanephric development, expressed in metanephric mesenchyme but not ureteric bud-derived cells, with overall expression being most abundant in the nephrogenic zone. From 14.5 dpc to birth, expressed at constant levels. By day 13, corresponding to the end of new nephron induction, expression levels begin to decline. By day 19, expression returned to fetal levels, and by day 40, the low level of expression that persisted into adulthood is established. In adult kidney, expression is restricted to podocytes. Expressed in pancreatic tissue from 12.5 dpc until 17.5 dpc. Is still detectable at low level,at postnatal day 1 and in isolated pancreatic islets in adult (PubMed:18560595). Specifically activated by bHLH factors. The bHLH domain mediates transcriptional repression by inhibiting TCF3 transcriptional activity through heterodimerization. Mice heterozygous survive to adulthood and present no phenotype (PubMed:18560595). The homozygous knockout of Atoh8 is embryonic lethal (PubMed:18560595). Contains a degenerate basic motif not likely to bind DNA.