# An Automated Imaging-Based Screen for Genetic Modulators of ER Organisation in Cultured Human Cells

## TL;DR

This paper introduces a new automated method to study how genes affect the structure of the endoplasmic reticulum in human cells, focusing on genes linked to a neurological disorder.

## Contribution

The study presents the first automated, high-content image-based screen for genetic modulators of ER organization in mammalian cells.

## Key findings

- siRNA knockdown of HSP genes ATL1 and RTN2 caused significant changes in tubular and dense sheet ER organization.
- The screen enables quantitative analysis of ER morphology, overcoming previous reliance on qualitative observations.

## Abstract

Hereditary spastic paraplegias (HSPs) are a heterogeneous group of mono-genetic inherited neurological disorders, whose primary manifestation is the disruption of the pyramidal system, observed as a progressive impaired gait and leg spasticity in patients. Despite the large list of genes linked to this group, which exceeds 80 loci, the number of cellular functions which the gene products engage is relatively limited, among which endoplasmic reticulum (ER) morphogenesis appears central. Mutations in genes encoding ER-shaping proteins are the most common cause of HSP, highlighting the importance of correct ER organisation for long motor neuron survival. However, a major bottleneck in the study of ER morphology is the current lack of quantitative methods, with most studies to date reporting, instead, on qualitative changes. Here, we describe and apply a quantitative image-based screen to identify genetic modifiers of ER organisation using a mammalian cell culture system. An analysis reveals significant quantitative changes in tubular ER and dense sheet ER organisation caused by the siRNA-mediated knockdown of HSP-causing genes ATL1 and RTN2. This screen constitutes the first attempt to examine ER distribution in cells in an automated and high-content manner and to detect genes which impact ER organisation.