Dysregulation of voltage-gated sodium channels (VGSC) is a prominent risk factor for autism spectrum disorder (ASD). Perturbations of VGSC and their interactors often lead to critical impairments in axonal and synaptic functions that eventually contribute to atypical neurobiology in ASD. Meanwhile, modulation of these interactions may also provide new opportunities to ameliorate phenotypes associated with different genetic predispositions. Despite this vital importance, our understanding of these VGSC-linked functional interactions remains limited.

To address this bottleneck, Yudong Gao developed a new method to map endogenous proximity proteomes in vivo using a combination of gene editing and proximity labeling approaches during his recent postdoctoral training at Duke University with Scott Soderling ¹. By targeting prominent ASD-risk proteins (e.g., NaV1.2, NaV1.6, and Ankyrin-G), Gao and his colleagues identified networks of protein interactions that may inform previously unrecognized molecular mechanisms of ASD. In particular, Dr. Gao identified a cluster of proteins in the proximity proteomes of VGSC that are involved in endosomal trafficking (e.g. Rab11fip5, Cc2d1a, Itsn1). All of these proteins are encoded by candidate ASD risk genes themselves. Their association with VGSC proteomes elicits a new hypothesis that these candidate proteins may contribute to ASD risk via a common mechanism in regulating VGSC membrane trafficking.

In his newly established laboratory at Baylor College of Medicine, Gao’s team is investigating the molecular and functional convergence of these candidates in VGSC regulation through multimodal proteomic, electrophysiological, and pharmacological interrogations Localization of ASD risk proteins in mouse neurons will be assessed using internal V5 epitope tags and their proximity proteomes will be identified with proximity labeling (TurboID). The impact on VGSC membrane presentation and function after CRISPR-knockout (KO) of Rab11fip5, Cc2d1a and Itsn1 in mice will be assessed with surface biotinylation and mass spectrometry (LC-MS/MS). To assess what effects changes in VGSC expression and cellular localization may have on neural activity, primary neurons from mice subjected to CRISPR-KO will be electrophysiologically characterized using MEA recordings. The research is expected to uncover underlying mechanisms of ASD associated with VGSC membrane trafficking and shine a light on potential therapeutic strategies targeting VGSC and their proximity interactors.

1. Gao Y. et al. Nat. Commun. 15, 6801 (2024) PubMed