CYP2U1 activity is altered by missense mutations in hereditary spastic paraplegia 56.
Human Mutation. 2017-11-11; 39(1): 140-151
DOI: 10.1002/humu.23359
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Durand CM(1), Dhers L(2), Tesson C(3)(4), Tessa A(5), Fouillen L(6), Jacqueré
S(1), Raymond L(3)(4), Coupry I(1), Benard G(1), Darios F(3), El-Hachimi
KH(3)(4), Astrea G(5), Rivier F(7), Banneau G(8), Pujol C(3), Lacombe D(1)(9),
Durr A(3)(8), Babin PJ(1), Santorelli FM(5), Pietrancosta N(2)(10), Boucher
JL(2), Mansuy D(2), Stevanin G(3)(4)(8), Goizet C(1)(9).
Author information:
(1)INSERM U1211, Laboratoire Maladies Rares: Génétique et Métabolisme. Bordeaux
University, Bordeaux, France.
(2)UMR 8601 CNRS, University Paris Descartes, Paris Sorbonne Cité, Paris, France.
(3)Institut du Cerveau et de la Moelle épinière, INSERM U1127, Sorbonne
Universités, UPMC UMR_S 1127, CNRS UMR 7225, Paris, France.
(4)Ecole Pratique des Hautes Etudes, EPHE, PSL Research University, Paris,
France.
(5)IRCCS Fondazione Stella Maris, Molecular Medicine, Calambrone, Italy.
(6)Laboratoire de Biogenèse Membranaire-UMR 5200, CNRS, Bordeaux University,
Bordeaux, France.
(7)Département de Neuropédiatrie – CR Maladies Neuromusculaires AOC, CHU de
Montpellier, U1046 INSERM UMR9214 CNRS, Montpellier University, Montpellier,
France.
(8)APHP, Department of Genetics, Pitié-Salpêtrière University Hospital, Paris,
France.
(9)Service de Génétique Médicale, CHU Pellegrin, Bordeaux, France.
(10)Team Chemistry & Biology, Modeling & Immunology for Therapy, CBMIT, 2MI
Platform, Paris, France.
Hereditary spastic paraplegia (HSP) is an inherited disorder of the central
nervous system mainly characterized by gradual spasticity and weakness of the
lower limbs. SPG56 is a rare autosomal recessive early onset complicated form of
HSP caused by mutations in CYP2U1. The CYP2U1 enzyme was shown to catalyze the
hydroxylation of arachidonic acid. Here, we report two further SPG56 families
carrying three novel CYP2U1 missense variants and the development of an in vitro
biochemical assay to determine the pathogenicity of missense variants of
uncertain clinical significance. We compared spectroscopic, enzymatic, and
structural (from a 3D model) characteristics of the over expressed wild-type or
mutated CYP2U1 in HEK293T cells. Our findings demonstrated that most of the
tested missense variants in CYP2U1 were functionally inactive because of a loss
of proper heme binding or destabilization of the protein structure. We also
showed that functional data do not necessarily correlate with in silico
predictions of variants pathogenicity, using different bioinformatic phenotype
prediction tools. Our results therefore highlight the importance to use
biological tools, such as the enzymatic test set up in this study, to evaluate
the effects of newly identified variants in clinical settings.
© 2017 Wiley Periodicals, Inc.