Biochemical Characterization of the GBA2 c.1780G>C Missense Mutation in Lymphoblastoid Cells from Patients with Spastic Ataxia

Int J Mol Sci. 2018 Oct 10;19(10):3099. doi: 10.3390/ijms19103099.

Anna Malekkou ¹ ², Maura Samarani ³, Anthi Drousiotou ⁴ ⁵, Christina Votsi ⁶ ⁷, Sandro Sonnino ⁸, Marios Pantzaris ⁹ ¹⁰, Elena Chiricozzi ¹¹, Eleni Zamba-Papanicolaou ¹² ¹³, Massimo Aureli ¹⁴, Nicoletta Loberto ¹⁵, Kyproula Christodoulou ¹⁶ ¹⁷

Affiliations

1 Biochemical Genetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. annama@cing.ac.cy.
2 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. annama@cing.ac.cy.
3 Department of Medical Biotechnology and Translational Medicine, University of Milano, 20122 Milano, Italy. maura.samarani@unimi.it.
4 Biochemical Genetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. anthidr@cing.ac.cy.
5 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. anthidr@cing.ac.cy.
6 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. votsi@cing.ac.cy.
7 Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. votsi@cing.ac.cy.
8 Department of Medical Biotechnology and Translational Medicine, University of Milano, 20122 Milano, Italy. sandro.sonnino@unimi.it.
9 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. pantzari@cing.ac.cy.
10 Neurology Clinic C, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. pantzari@cing.ac.cy.
11 Department of Medical Biotechnology and Translational Medicine, University of Milano, 20122 Milano, Italy. elena.chiricozzi@unimi.it.
12 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. ezamba@cing.ac.cy.
13 Neurology Clinic D, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. ezamba@cing.ac.cy.
14 Department of Medical Biotechnology and Translational Medicine, University of Milano, 20122 Milano, Italy. massimo.aureli@unimi.it.
15 Department of Medical Biotechnology and Translational Medicine, University of Milano, 20122 Milano, Italy. nicoletta.loberto@unimi.it.
16 Cyprus School of Molecular Medicine, Nicosia 1683, Cyprus. roula@cing.ac.cy.
17 Neurogenetics Department, The Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus. roula@cing.ac.cy.

PMID: 30308956 DOI: 10.3390/ijms19103099

Abstract

The GBA2 gene encodes the non-lysosomal glucosylceramidase (NLGase), an Enzyme that catalyzes the conversion of glucosylceramide (GlcCer) to ceramide and glucose. Mutations in GBA2 have been associated with the development of neurological disorders such as autosomal recessive cerebellar ataxia, hereditary spastic paraplegia, and Marinesco-Sjogren-Like Syndrome. Our group has previously identified the GBA2 c.1780G>C [p.Asp594His] missense mutation, in a Cypriot consanguineous family with spastic ataxia. In this study, we carried out a biochemical characterization of lymphoblastoid cell lines (LCLs) derived from three patients of this family. We found that the mutation strongly reduce NLGase activity both intracellularly and at the plasma membrane level. Additionally, we observed a two-fold increase of GlcCer content in LCLs derived from patients compared to controls, with the C₁₆ lipid being the most abundant GlcCer species. Moreover, we showed that there is an apparent compensatory effect between NLGase and the lysosomal glucosylceramidase (GCase), since we found that the activity of GCase was three-fold higher in LCLs derived from patients compared to controls. We conclude that the c.1780G>C mutation results in NLGase loss of function with abolishment of the enzymatic activity and accumulation of GlcCer accompanied by a compensatory increase in GCase.

Keywords

GBA2; glucosylceramide; lymphoblastoid cell lines; non-lysosomal β-glucosylceramidase; plasma membrane; spastic ataxia; β-glucocerebrosidase.

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