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Kitakaze K, Tasaki C, Tajima Y, Hirokawa T, Tsuji D, Sakuraba H, Itoh K. Combined replacement effects of human modified β-hexosaminidase B and GM2 activator protein on GM2 gangliosidoses fibroblasts. Biochem Biophys Rep 2016; 7:157-163. [PMID: 28955902 PMCID: PMC5613250 DOI: 10.1016/j.bbrep.2016.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/24/2016] [Accepted: 04/27/2016] [Indexed: 01/17/2023] Open
Abstract
GM2 gangliosidoses are autosomal recessive lysosomal storage diseases (LSDs) caused by mutations in the HEXA, HEXB and GM2A genes, which encode the human lysosomal β-hexosaminidase (Hex) α- and β-subunits, and GM2 activator protein (GM2A), respectively. These diseases are associated with excessive accumulation of GM2 ganglioside (GM2) in the brains of patients with neurological symptoms. Here we established a CHO cell line overexpressing human GM2A, and purified GM2A from the conditioned medium, which was taken up by fibroblasts derived from a patient with GM2A deficiency, and had the therapeutic effects of reducing the GM2 accumulated in fibroblasts when added to the culture medium. We also demonstrated for the first time that recombinant GM2A could enhance the replacement effect of human modified HexB (modB) with GM2-degrading activity, which is composed of homodimeric altered β-subunits containing a partial amino acid sequence of the α-subunit, including the GSEP loop necessary for binding to GM2A, on reduction of the GM2 accumulated in fibroblasts derived from a patient with Tay-Sachs disease, a HexA (αβ heterodimer) deficiency, caused by HEXA mutations. We predicted the same manner of binding of GM2A to the GSEP loop located in the modified HexB β-subunit to that in the native HexA α-subunit on the basis of the x-ray crystal structures. These findings suggest the effectiveness of combinational replacement therapy involving the human modified HexB and GM2A for GM2 gangliosidoses. Purification of recombinant human GM2A proteins by CHO cell line overexpressing GM2A. Reduction of GM2 accumulated in GM2A deficiency fibroblasts by GM2A replacement. Combined effects of modified HexB and GM2A for HexA deficiency fibroblasts. In silico prediction of molecular interaction between modified HexB and GM2A.
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Key Words
- CI-M6PR, cation-independent M6P receptor
- CM, conditioned medium
- ERT, enzyme replacement therapy
- Enzyme replacement therapy
- GM2, GM2 ganglioside
- GM2A, GM2 activator protein
- Gm2 activator protein
- Gm2 gangliosidosis
- Hex, β-hexosaminidase
- LAMP-1, lysosomal associated membrane protein 1
- LSD, lysosomal storage disease
- Lysosomal storage disease
- M6P, mannose-6-phosphate
- SD, Sandhoff disease
- TSD, Tay-Sachs disease
- modB, modified HexB
- β-hexosaminidase
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Affiliation(s)
- Keisuke Kitakaze
- Department of Medicinal Biotechnology, Institute of Biomedical Sciences, Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1, Tokushima 770-8505, Japan
| | - Chikako Tasaki
- Department of Medicinal Biotechnology, Institute of Biomedical Sciences, Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1, Tokushima 770-8505, Japan
| | - Youichi Tajima
- Molecular Medical Research Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Takatsugu Hirokawa
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Daisuke Tsuji
- Department of Medicinal Biotechnology, Institute of Biomedical Sciences, Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1, Tokushima 770-8505, Japan
| | - Hitoshi Sakuraba
- Department of Clinical Genetics, Meiji Pharmaceutical University, Tokyo 204-8588, Japan
| | - Kohji Itoh
- Department of Medicinal Biotechnology, Institute of Biomedical Sciences, Graduate School of Pharmaceutical Science, Tokushima University, 1-78-1, Tokushima 770-8505, Japan
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