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Cited by 1Genetic and Kidney Cyst DiseasesCystic Fibrosis Research AdvancesHereditary Neurological Disorders

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Intraflagellar transport protein IFT172 contains a C-terminal ubiquitin-binding U-box-like domain involved in ciliary signaling

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Zacharia, Nevin K, Kuhns, Stefanie, Boegholm, Niels, Christensen, Anni, Wang, Jiaolong, Petriman, Narcis A, Lorentzen, Anna, Fialova, Jindriska L, Menguy, Lucie, Saunier, Sophie, Christensen, Søren Tvorup, Andersen, Jens S, Bhogaraju, Sagar, Lorentzen, Esben·2026·eLife
DOI 10.7554/elife.104906.3

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Abstract

Intraflagellar transport (IFT) is a fundamental process driving ciliogenesis in most eukaryotic organisms. IFT172, the largest protein of the IFT complex, plays a crucial role in cilium formation, and several disease-causing IFT172 variants have been identified in ciliopathy patients. While IFT172 is tethered to the IFT-B complex via its N-terminal domains, the function of its C-terminal domains has remained elusive. Here, using both human and Chlamydomonas reinhardtii IFT172, we reveal that the C-terminal part of IFT172 interacts with IFT-A complex subunits, providing a molecular basis for the role of IFT172 in bridging IFT-A and IFT-B complexes. We determine the crystal structure of the C-terminal part of IFT172, uncovering a conserved U-box-like domain often found in E3 ubiquitin ligases. This domain exhibits ubiquitin-binding properties, and IFT172 undergoes ubiquitin conjugation in vitro, an activity that is reduced in the C1727R patient ciliopathy variant. We use CRISPR-engineered RPE-1 cells to demonstrate that the U-box-like domain is essential for IFT172 protein stability and proper cilium formation. Notably, RPE-1 cells with heterozygous deletion of the U-box domain show altered TGF-β signaling responses, particularly in SMAD2 phosphorylation levels and AKT activation. Our findings suggest that IFT172, beyond its structural role in bridging IFT-A and IFT-B complexes within IFT trains, harbors a conserved U-box-like domain with potential involvement in ciliary ubiquitination processes and signaling, providing new insights into the molecular mechanisms underlying IFT172-related ciliopathies.

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Metadata

Authors
Zacharia, N. K., Kuhns, S., Boegholm, N., Christensen, A., Wang, J., Petriman, N. A., Lorentzen, A., Fialova, J. L., Menguy, L., Saunier, S., Christensen, S. T., Andersen, J. S., Bhogaraju, S., & Lorentzen, E.
Affiliations
  • Aarhus University (DK)
  • University of Southern Denmark (DK)
  • University of Copenhagen (DK)
  • Department of Biology, University of Copenhagen, Universitetsparken
  • Institut des Maladies Génétiques Imagine (FR)
  • European Molecular Biology Laboratory (FR)
Corresponding author
Lorentzen, Esben
ORCID
Venue
eLife
Publisher
eLife Sciences Publications, Ltd
Published
2026-06-23
Volume
14
ISSN
2050-084X (ISSN-L)
DOI
10.7554/elife.104906.3
OpenAlex
W4404059670
Cited by
1
References
8
Citations by year
2026: 1
FWCI
4.05
Type
journal article
Language
en
Open access
Licence
Locations
  • eLife (publishedVersion, cc-by)
  • eLife (acceptedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
Funders
  • Novo Nordisk Fonden (NNF23OC0085823, NNF15OC00114164, NNF18SA0032928)
  • Horizon 2020 Framework Programme (10.3030/861329)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic and Kidney Cyst Diseases
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Cystic Fibrosis Research Advances
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Hereditary Neurological Disorders
Keywords
IFT172, intraflagellar transport, ubiquitin binding, ubiquitination, ciliopathies, IFT-A complex, IFT-B complex, ciliary signaling, TGF-beta signaling, Smad2 phosphorylation, Akt activation, protein stability, ciliogenesis, RPE1 cells

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