# Endoplasmic reticulum patterns insect cuticle nanostructure

## TL;DR

This paper reveals how the endoplasmic reticulum helps form nanoscale structures in insect cuticles, using a protein called Gore-tex in fruit flies.

## Contribution

The study identifies a novel ER-to-plasma membrane trafficking pathway involving Gore-tex and ER-phagy in nanopore formation.

## Key findings

- Gore-tex (Gox) regulates ER-phagy and endocytosis to form cuticular nanopores.
- ER and plasma membrane bidirectional interactions are essential for nanopatterning.
- ER-phagy is repurposed for plasma membrane remodeling and ECM structure fabrication.

## Abstract

An extensive ER network develops in the olfactory hair cells of Drosophila. Inagaki et al. report that the transmembrane protein Gore-tex controls a novel ER to the plasma membrane trafficking pathway essential for the cuticular nanopore formation.

Insect cuticles with nano-level structures exhibit functional surface properties such as the photonic nanocrystal of the butterfly wing scale with structural color and the corneal nipple arrays of superhydrophobic compound eye lens. Despite the enormous influence the cuticle has had on biomimetic industrial applications, cellular mechanisms of cuticular nanopatterning remain poorly understood. Drosophila gore-tex/Osiris23 (gox) controls the formation of nanopores, with a molecular filtering function, on the olfactory organs. Here we used 3D electron microscopy imaging of entire hair structures to show that nanopore is formed through a novel process of bidirectional interaction of the ER and the plasma membrane trafficking. ER-resident protein Gox stimulates ER-phagy through regulation of Ref(2)P, the fly counterpart of the autophagy protein p62/SQSTM1, and initiates endocytosis. Dynamin on the plasma membrane completes endocytosis and sustains ER-phagy. The repurposing of ER-phagy for plasma membrane remodeling and the fabrication of nanoscale ECM structures sheds light on the nanopatterning mechanism of insect cuticles and their genetic control.