The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules

Abstract Most eukaryotic cells have cilia that serve vital functions in sensing, signalling, motility. The core architecture of cilia is an array of microtubule doublets, which consist of a complete A-tubule and an incomplete B-tubule. How these structures assemble remains poorly understood. Using t...

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Main Authors: Dharshini Gopal, Juliette Wu, Julie Delaroche, Christophe Bosc, Manon De Andrade, Eric Denarier, Gregory Effantin, Annie Andrieux, Sylvie Gory-Fauré, Laurence Serre, Isabelle Arnal
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-61679-0
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author Dharshini Gopal
Juliette Wu
Julie Delaroche
Christophe Bosc
Manon De Andrade
Eric Denarier
Gregory Effantin
Annie Andrieux
Sylvie Gory-Fauré
Laurence Serre
Isabelle Arnal
author_facet Dharshini Gopal
Juliette Wu
Julie Delaroche
Christophe Bosc
Manon De Andrade
Eric Denarier
Gregory Effantin
Annie Andrieux
Sylvie Gory-Fauré
Laurence Serre
Isabelle Arnal
author_sort Dharshini Gopal
collection DOAJ
description Abstract Most eukaryotic cells have cilia that serve vital functions in sensing, signalling, motility. The core architecture of cilia is an array of microtubule doublets, which consist of a complete A-tubule and an incomplete B-tubule. How these structures assemble remains poorly understood. Using total internal reflection fluorescence microscopy and cryo-electron tomography, we investigate the role of MAP6d1, a brain-specific protein containing microtubule lumen-targeting Mn-motifs. We show that MAP6d1 assembles stable microtubule doublets by recruiting tubulin dimers onto the A-tubule lattice to initiate B-tubule nucleation. MAP6d1 also promotes the formation of luminal protofilaments in singlet and doublet microtubules, a previously undescribed phenomenon that likely enhances microtubule stability. In neurons, MAP6d1 localises to the proximal part of primary cilia via its Mn-motif, with its loss resulting in shortened cilia, a characteristic of ciliopathies. MAP6d1 is thus a neuronal Mn-motif protein with a specific role in assembling microtubule doublets and regulating ciliary length.
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spelling doaj-art-076dee8a5b674a2682f7b49937e489ae2025-08-20T03:03:33ZengNature PortfolioNature Communications2041-17232025-07-0116111510.1038/s41467-025-61679-0The Mn-motif protein MAP6d1 assembles ciliary doublet microtubulesDharshini Gopal0Juliette Wu1Julie Delaroche2Christophe Bosc3Manon De Andrade4Eric Denarier5Gregory Effantin6Annie Andrieux7Sylvie Gory-Fauré8Laurence Serre9Isabelle Arnal10Grenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesInstitut de Biologie Structurale (IBS), CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesGrenoble Institut Neurosciences (GIN), INSERM, U1216, CNRS, CEA, Université Grenoble AlpesAbstract Most eukaryotic cells have cilia that serve vital functions in sensing, signalling, motility. The core architecture of cilia is an array of microtubule doublets, which consist of a complete A-tubule and an incomplete B-tubule. How these structures assemble remains poorly understood. Using total internal reflection fluorescence microscopy and cryo-electron tomography, we investigate the role of MAP6d1, a brain-specific protein containing microtubule lumen-targeting Mn-motifs. We show that MAP6d1 assembles stable microtubule doublets by recruiting tubulin dimers onto the A-tubule lattice to initiate B-tubule nucleation. MAP6d1 also promotes the formation of luminal protofilaments in singlet and doublet microtubules, a previously undescribed phenomenon that likely enhances microtubule stability. In neurons, MAP6d1 localises to the proximal part of primary cilia via its Mn-motif, with its loss resulting in shortened cilia, a characteristic of ciliopathies. MAP6d1 is thus a neuronal Mn-motif protein with a specific role in assembling microtubule doublets and regulating ciliary length.https://doi.org/10.1038/s41467-025-61679-0
spellingShingle Dharshini Gopal
Juliette Wu
Julie Delaroche
Christophe Bosc
Manon De Andrade
Eric Denarier
Gregory Effantin
Annie Andrieux
Sylvie Gory-Fauré
Laurence Serre
Isabelle Arnal
The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
Nature Communications
title The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
title_full The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
title_fullStr The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
title_full_unstemmed The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
title_short The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules
title_sort mn motif protein map6d1 assembles ciliary doublet microtubules
url https://doi.org/10.1038/s41467-025-61679-0
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