The C. elegans homolog of human panic-disorder risk gene TMEM132D orchestrates neuronal morphogenesis through the WAVE-regulatory complex

Xin Wang,Wei Jiang,Dengke K Ma,Shuo Luo,Yin Shen,Xiaoyu Yang,Yongjun Dang,Changnan Wang,Bingying Wang

doi:10.1186/s13041-021-00767-w

Abstract

TMEM132D is a human gene identified with multiple risk alleles for panic disorders, anxiety and major depressive disorders. Defining a conserved family of transmembrane proteins, TMEM132D and its homologs are still of unknown molecular functions. By generating loss-of-function mutants of the sole TMEM132 ortholog in C. elegans, we identify abnormal morphologic phenotypes in the dopaminergic PDE neurons. Using a yeast two-hybrid screen, we find that NAP1 directly interacts with the cytoplasmic domain of human TMEM132D, and mutations in C. elegans tmem-132 that disrupt interaction with NAP1 cause similar morphologic defects in the PDE neurons. NAP1 is a component of the WAVE regulatory complex (WRC) that controls F-actin cytoskeletal dynamics. Decreasing activity of WRC rescues the PDE defects in tmem-132 mutants, whereas gain-of-function of TMEM132D in mammalian cells inhibits WRC, leading to decreased abundance of select WRC components, impaired actin nucleation and cell motility. We propose that metazoan TMEM132 family proteins play evolutionarily conserved roles in regulating NAP1 protein homologs to restrict inappropriate WRC activity, cytoskeletal and morphologic changes in the cell.

Highlights

Despite decades of genetic and molecular analyses, the genome of the common model organism C. elegans still comprises many functionally uncharacterized genes [1,2,3,4]
We used CRISPR-Cas9 techniques to generate a series of C. elegans mutants, including multiple independentlyderived deletions, an early stop-codon mutant and a genetic P784T knock-in mutant, in which the highly conserved proline residue became threonine, corresponding to the human disease risk allele for anxiety and panic disorders (Fig. 1e, f )
WAVE-regulatory complex (WRC) acts downstream of TMEM‐132 to regulate morphology of the PDE neurons Since C. elegans TMEM-132 binds to GEX-3 as human TMEM132D binds to NAP1, we addressed whether TMEM-132 regulates neuronal morphology via WRC in C. elegans

Summary

Introduction

Despite decades of genetic and molecular analyses, the genome of the common model organism C. elegans still comprises many functionally uncharacterized genes [1,2,3,4] One such example is the C. elegans gene Y71H2AM., an ortholog of the evolutionarily conserved TMEM132 gene family [1, 5]. Whether NAP1 directly interacts with any neuronal membrane receptors to affect WRC signaling and actin cytoskeletal changes has not been reported. It has been unclear how WRC abundance is regulated in cell compartments where actin nucleation needs to be limited in morphologically complex cells, including neurons

Methods

Results

Conclusion