Work

SANS ankyrin repeats mediate non‐classical nuclear import and dictate distinct pathogenic mechanisms

Year: 2026

Type: article

Abstract: Mutations in the USH1G gene, which encodes the scaffold protein SANS, cause type-I Usher syndrome, a severe inherited disorder involving both hearing and vision loss. Although SANS has been implicated in nuclear pre-mRNA splicing, the molecular determinants of its nuclear import and their relevance to USH1G pathogenesis remain incompletely understood. Here, we report high-resolution crystal structures of the N-terminal ankyrin repeat regions of SANS and its homolog ANKS4B. We show that SANS_AR functions as a self-sufficient module that promotes nuclear localization, whereas ANKS4B_AR lacks this property. Structure-guided analysis of USH1G-associated variants suggests two distinct classes of effects: core hydrophobic mutations such as L48P, L84P impair SANS_AR solubility and are predicted to destabilize the domain, whereas surface-exposed substitutions such as R10W, S119P, and R146C remain compatible with soluble expression but reduce SANS nuclear localization. Together, these findings provide a molecular framework for understanding how impaired SANS_AR stability and defective nuclear localization may contribute to USH1G pathogenesis.

Source: FEBS Journal

DOI: 10.1111/febs.70708

Authors: Wenxia Yan, Guanhao Chen, Liping Wang, Jianchao Li

Institutions: Shanxi Medical University, Shanxi Academy of Medical Sciences, South China University of Technology

Language: English

Topic: RNA Research and Splicing

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: National Natural Science Foundation of China, Southern University of Science and Technology, Special Project for Research and Development in Key areas of Guangdong Province, Basic and Applied Basic Research Foundation of Guangdong Province