Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8258842 | Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease | 2017 | 28 Pages |
Abstract
The neuron-restricted isoform 3 of the plasma membrane Ca2Â + ATPase plays a major role in the regulation of Ca2Â + homeostasis in the brain, where the precise control of Ca2Â + signaling is a necessity. Several function-affecting genetic mutations in the PMCA3 pump associated to X-linked congenital cerebellar ataxias have indeed been described. Interestingly, the presence of co-occurring mutations in additional genes suggest their synergistic action in generating the neurological phenotype as digenic modulators of the role of PMCA3 in the pathologies. Here we report a novel PMCA3 mutation (G733R substitution) in the catalytic P-domain of the pump in a patient affected by non-progressive ataxia, muscular hypotonia, dysmetria and nystagmus. Biochemical studies of the pump have revealed impaired ability to control cellular Ca2Â + handling both under basal and under stimulated conditions. A combined analysis by homology modeling and molecular dynamics have revealed a role for the mutated residue in maintaining the correct 3D configuration of the local structure of the pump. Mutation analysis in the patient has revealed two additional function-impairing compound heterozygous missense mutations (R123Q and G214S substitution) in phosphomannomutase 2 (PMM2), a protein that catalyzes the isomerization of mannose 6-phosphate to mannose 1-phosphate. These mutations are known to be associated with Type Ia congenital disorder of glycosylation (PMM2-CDG), the most common group of disorders of N-glycosylation. The findings highlight the association of PMCA3 mutations to cerebellar ataxia and strengthen the possibility that PMCAs act as digenic modulators in Ca2Â +-linked pathologies.
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Authors
Mattia Vicario, Tito Calì, Domenico Cieri, Francesca Vallese, Raissa Bortolotto, Raffaele Lopreiato, Francesco Zonta, Marta Nardella, Alessia Micalizzi, Dirk J. Lefeber, Enza Maria Valente, Enrico Bertini, Giuseppe Zanotti, Ginevra Zanni, Marisa Brini,