Astn

Astn is a term used to refer to the astrotactin gene family in vertebrates, principally the genes ASTN1 and ASTN2. The proteins encoded by these genes are large transmembrane glycoproteins with substantial extracellular domains and relatively short cytoplasmic tails. ASTN1 and ASTN2 share structural features and are expressed in the developing brain, with ASTN1 being more closely tied to migratory processes and ASTN2 contributing to additional cellular functions.

In terms of expression, ASTN1 and ASTN2 are observed in neural tissue during embryonic development and persist into later stages in specific brain regions. Their spatial and temporal patterns support roles in the formation and maturation of neural circuits, with ASTN1 more prominently associated with early neuronal migration and ASTN2 implicated in broader aspects of membrane protein trafficking and neuron–glia interactions.

Biological function centers on the guidance of neuronal migration along radial glial fibers, a critical process for proper cortical and cerebellar lamination. ASTN1 has been studied as a mediator of neuron–glia adhesion during migration, while ASTN2 is thought to influence the trafficking and surface expression of other membrane proteins, thereby impacting synapse formation and neuronal maturation. The precise mechanisms and extent of their contributions continue to be investigated.

Clinical significance is most clearly linked to ASTN2, where variants and copy-number changes have been associated with neurodevelopmental conditions such as autism spectrum disorder and intellectual disability in multiple studies. The relationship between ASTN1 alterations and disease is less consistently reported. Animal models with disrupted astrotactin genes show migration defects, underscoring the developmental importance of this gene family.

See also: ASTN1, ASTN2, astrotactin.