DIAPH1 Summary

Protein diaphanous homolog 1 (DIAPH1) is an actin nucleation and elongation factor that regulates the assembly of F-actin structures including actin cables and stress fibers (UniProt: O60610). The protein functions as a molecular scaffold coupling Rho and Src tyrosine kinase signaling to control actin dynamics and microtubule stability; it also promotes neurite outgrowth and plays a role in brain development. DIAPH1 participates in the MEMO1-RHOA-DIAPH1 signaling pathway, which stabilizes microtubules at the cell cortex and regulates cell morphology through interactions with APC and other cytoskeletal regulators (UniProt: O60610).

DIAPH1 mutations are associated with Mendelian neurodevelopmental and hearing disorders, including autosomal dominant deafness (DFNA1) and seizures, cortical blindness, and microcephaly syndrome (SCBMS) (UniProt: O60610). The protein's involvement in neuronal morphogenesis and cytoskeletal organization suggests broader relevance to nervous system function.

In Alzheimer's disease, DIAPH1 is significantly downregulated in post-mortem human brain tissue relative to age-matched controls (mean log2 fold-change −1.02; Chaparral AD proteomics). This reduction in an actin-regulatory protein implicated in neuronal structural integrity may contribute to the synaptic and cytoskeletal dysfunction characteristic of AD pathology.