EVC-EVC2 complex stability and ciliary targeting are regulated by modification with ubiquitin and SUMO

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Ellis van Creveld syndrome and Weyers acrofacial dysostosis are rare genetic ciliopathies impacting skeletal development.
• These conditions stem from defects in the EVC-EVC2 complex, crucial for Hedgehog signaling in primary cilia during skeletal morphogenesis.
• The precise mechanisms governing the stability, targeting, and function of the EVC-EVC2 complex remain poorly understood.

Purpose of the Study:

• To elucidate the regulatory mechanisms of the EVC-EVC2 complex.
• To identify novel interactors and post-translational modifications affecting EVC-EVC2 complex function.
• To understand the implications of these regulatory mechanisms for ciliopathies.

Main Methods:

• Proteomic analysis to characterize the endogenous EVC protein interactome in control and Evc-null cells.
• Investigation of EVC-EVC2 complex ubiquitination and SUMOylation.
• Mapping of EFCAB7-binding motifs within EVC2 for EvC zone targeting.

Main Results:

• Confirmed known EVC interactors and identified USP7 as a novel interactor.
• Demonstrated that EVC-EVC2 complex ubiquitination, independent of USP7, reduces protein levels, while SUMOylation enhances complex accumulation at the EvC zone.
• Mapped a second EFCAB7-binding motif in EVC2 essential for EvC zone targeting.

Conclusions:

• Post-translational modifications, specifically ubiquitination and SUMOylation, play critical roles in regulating EVC-EVC2 complex stability and localization.
• The findings provide new insights into the molecular mechanisms underlying Ellis van Creveld syndrome and Weyers acrofacial dysostosis.
• This research advances our understanding of ciliopathy pathogenesis and potential therapeutic targets.