# Coordination of IFT20 With Other IFT Components Is Required for Ciliogenesis

## TL;DR

This study shows that IFT20 is crucial for forming cell structures called cilia by coordinating with other transport proteins, and its absence leads to ciliary defects.

## Contribution

The study reveals that IFT20 regulates ciliogenesis by coordinating with other IFT proteins, which was previously unknown.

## Key findings

- IFT20 deficiency impairs ciliogenesis and reduces cilium length.
- IFT20 interacts with IFT88 and IFT140, affecting their levels and localization.
- IFT20 knockout does not affect CP110 removal or MKS3 recruitment.

## Abstract

Primary cilia are organelles formed on the cell surface. They can act as cellular antennae to sense signals and play important roles in various biological processes. Abnormalities in primary cilia lead to a variety of diseases collectively known as ciliopathies. Intraflagellar transport protein 20 (IFT20) has been implicated in ciliogenesis.

IFT20 knockout cell lines were established using the CRISPR‐Cas9 gene editing technology. The GFP‐IFT20 plasmid was constructed with the Gateway cloning system. Protein levels were detected via immunoblotting, and the localization of IFT20, acetylated α‐tubulin, ARL13B, CP110, MKS3, IFT88, and IFT140 in wild‐type and IFT20 knockout cells was examined by immunofluorescence microscopy. The fluorescence intensities were analyzed using ImageJ. Data quantifications and mass spectrometry results were analyzed using GraphPad Prism and Metascape.

The IFT20 deficiency impaired ciliogenesis and reduced cilium length. IFT20 depletion did not affect the removal of centriolar coiled‐coil protein 110 (CP110) from the mother centriole or the recruitment of Meckel–Gruber syndrome type 3 (MKS3) to the transition zone. Mass spectrometry analysis revealed that proteins interacting with IFT20 were mainly IFT components. IFT20 knockout decreased the levels of both IFT88 and IFT140, and abrogated IFT88 localization at the basal body and ciliary axoneme. IFT20 knockout also impaired IFT140 localization at the ciliary axoneme but did not affect its localization at the basal body.

IFT20 is involved in ciliogenesis by regulating the level and localization of other IFT proteins and may have important implications in ciliopathies and related diseases.

Intraflagellar transport is a bidirectional transport system essential for ciliogenesis. Using the IFT20 knockout cell lines established in this study, we found that IFT20 deficiency significantly impaired ciliogenesis and reduced cilium length. Further investigation revealed that IFT20 interacted with other IFT proteins and regulated their levels and localization to function in ciliogenesis.