EN1s

EN1s denotes the Engrailed-1 transcription factor family, referring to the EN1 gene and related orthologs across species. The EN1 gene encodes Engrailed-1, a homeobox-containing transcription factor that functions in developmental patterning. EN1 proteins act as transcriptional regulators that influence the expression of downstream genes during early neural development. They are typically expressed in the midbrain–hindbrain boundary region and in adjacent neural progenitors, where they interact with signaling pathways such as FGF and Wnt to establish regional identity. In vertebrates, EN1 works in concert with EN2, and the two genes can have overlapping and distinct roles.

In development, EN1 is essential for proper patterning of the midbrain and cerebellum. Loss-of-function mutations in model organisms produce defects in brain regionalization and cerebellar structure, underscoring EN1’s role in specifying neural progenitor fates. While much of the detailed mechanism comes from animal studies, these findings inform expectations about EN1's functions in humans, where EN1 is expressed in select brain regions, and its postnatal roles are less clearly defined. Abnormal EN1 expression has been examined in various model systems to understand neurodevelopmental processes, though direct causal links to human disease remain an area of ongoing research.

EN1 is part of the wider engrailed gene family, with EN2 as a closely related paralog. Together with other homeobox genes, EN1 contributes to the regulation of regional identity along the anterior–posterior axis in the developing brain.