CERT1 mutations perturb human development by disrupting sphingolipid homeostasis
Charlotte Gehin, et al.
Charlotte Gehin, et al.
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Research Article Cell biology Genetics

CERT1 mutations perturb human development by disrupting sphingolipid homeostasis

Abstract

Neural differentiation, synaptic transmission, and action potential propagation depend on membrane sphingolipids, whose metabolism is tightly regulated. Mutations in the ceramide transporter CERT (CERT1), which is involved in sphingolipid biosynthesis, are associated with intellectual disability, but the pathogenic mechanism remains obscure. Here, we characterize 31 individuals with de novo missense variants in CERT1. Several variants fall into a previously uncharacterized dimeric helical domain that enables CERT homeostatic inactivation, without which sphingolipid production goes unchecked. The clinical severity reflects the degree to which CERT autoregulation is disrupted, and inhibiting CERT pharmacologically corrects morphological and motor abnormalities in a Drosophila model of the disease, which we call ceramide transporter (CerTra) syndrome. These findings uncover a central role for CERT autoregulation in the control of sphingolipid biosynthetic flux, provide unexpected insight into the structural organization of CERT, and suggest a possible therapeutic approach for patients with CerTra syndrome.

Authors

Charlotte Gehin, Museer A. Lone, Winston Lee, Laura Capolupo, Sylvia Ho, Adekemi M. Adeyemi, Erica H. Gerkes, Alexander P.A. Stegmann, Estrella López-Martín, Eva Bermejo-Sánchez, Beatriz Martínez-Delgado, Christiane Zweier, Cornelia Kraus, Bernt Popp, Vincent Strehlow, Daniel Gräfe, Ina Knerr, Eppie R. Jones, Stefano Zamuner, Luciano A. Abriata, Vidya Kunnathully, Brandon E. Moeller, Anthony Vocat, Samuel Rommelaere, Jean-Philippe Bocquete, Evelyne Ruchti, Greta Limoni, Marine Van Campenhoudt, Samuel Bourgeat, Petra Henklein, Christian Gilissen, Bregje W. van Bon, Rolph Pfundt, Marjolein H. Willemsen, Jolanda H. Schieving, Emanuela Leonardi, Fiorenza Soli, Alessandra Murgia, Hui Guo, Qiumeng Zhang, Kun Xia, Christina R. Fagerberg, Christoph P. Beier, Martin J. Larsen, Irene Valenzuela, Paula Fernández-Álvarez, Shiyi Xiong, Robert Śmigiel, Vanesa López-González, Lluís Armengol, Manuela Morleo, Angelo Selicorni, Annalaura Torella, Moira Blyth, Nicola S. Cooper, Valerie Wilson, Renske Oegema, Yvan Herenger, Aurore Garde, Ange-Line Bruel, Frederic Tran Mau-Them, Alexis B.R. Maddocks, Jennifer M. Bain, Musadiq A. Bhat, Gregory Costain, Peter Kannu, Ashish Marwaha, Neena L. Champaigne, Michael J. Friez, Ellen B. Richardson, Vykuntaraju K. Gowda, Varunvenkat M. Srinivasan, Yask Gupta, Tze Y. Lim, Simone Sanna-Cherchi, Bruno Lemaitre, Toshiyuki Yamaji, Kentaro Hanada, John E. Burke, Ana Marija Jakšić, Brian D. McCabe, Paolo De Los Rios, Thorsten Hornemann, Giovanni D’Angelo, Vincenzo A. Gennarino

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Figure 5

Disease-causing CERT1 mutations affect the central core structure of CERT.

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Disease-causing CERT1 mutations affect the central core structure of CER...
(A) Domain organization of CERT with its CCD and the predicted H1 and H2 helices. The global percentage of HDX is shown for all peptides graphed according to their central residue number. The mean of 3 experiments is shown. (B) Deuterium incorporation over time of 4 selected peptides (highlighted with arrows on the HDX profile). Data are from Supplemental Tables 5 and 6. (C) Molecular model of CERT’s CCD based on contact prediction. Helix H1 is shown in yellow and H2 in red. (D) Thermostability of intervening regions showing a difference in HDX by circular dichroism: the samples were heated from 4°C to 94°C; the percentage indicates the helicity of each construct at 20°C. (E) Deconvoluted mass spectrum of purified recombinant CERT 151-309 WT. The value 18.5 kDa represents the molecular weight of the monomer, 37 kDa a dimer, and 71.5 kDa a tetramer. (F) Molecular model of CERT 151-309 WT as an antiparallel dimer. (G) Model showing the location of aa mutated in CerTra syndrome. The areas differentially exposed to deuterium exchange are indicated according to the color scale. (H) Molecular model of CERT WT as an antiparallel dimer. (I) Molecular model of CERT WT at the ER-TGN membrane contact site in its active and inactive conformations. (J) Thermostability of CERT 154-187 WT and p.T166A and CERT 151-309 WT and p.G243R by circular dichroism. (K) Peptide in the CCD displaying decreases in exchange in the p.G243R mutant compared with WT. These changes are mapped on the hypothetical CCD structure.