
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.04.611229
preprint
1
Article
Two functional forms of the Meckel-Gruber syndrome protein TMEM67 generated by proteolytic cleavage by ADAMTS9 mediate Wnt signaling and ciliogenesis
Ahmed Manu http://orcid.org/0000-0002-2841-1624

Fischer Sydney http://orcid.org/0000-0001-7366-7605

Robert Karyn L. http://orcid.org/0009-0006-1805-3989

Lange Karen I. http://orcid.org/0000-0002-2414-5277

Stuck Michael W. http://orcid.org/0000-0003-3387-5850

Best Sunayna http://orcid.org/0000-0002-8685-7800

Johnson Colin A.
Pazour Gregory J. http://orcid.org/0000-0002-6285-8796

Blacque Oliver E. http://orcid.org/0000-0003-1598-2695

Nandadasa Sumeda http://orcid.org/0000-0002-4954-6376

05 9 2024
2024.09.04.611229https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.09.04.611229
nihpp-2024.09.04.611229.pdf
ABSTRACT

TMEM67 mutations are the major cause of Meckel-Gruber syndrome. TMEM67 is involved in both ciliary transition zone assembly, and non-canonical Wnt signaling mediated by its extracellular domain. How TMEM67 performs these two separate functions is not known. We identify a novel cleavage motif in the extracellular domain of TMEM67 cleaved by the extracellular matrix metalloproteinase ADAMTS9. This cleavage regulates the abundance of two functional forms: A C-terminal portion which localizes to the ciliary transition zone regulating ciliogenesis, and a non- cleaved form which regulates Wnt signaling. By characterizing three TMEM67 ciliopathy patient variants within the cleavage motif utilizing mammalian cell culture and C. elegans, we show the cleavage motif is essential for cilia structure and function, highlighting its clinical significance. We generated a novel non-cleavable TMEM67 mouse model which develop severe ciliopathies phenocopying Tmem67 -/- mice, but in contrast, undergo normal Wnt signaling, substantiating the existence of two functional forms of TMEM67.
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