Characterization of New Transgenic Mouse Models for Two Charcot-Marie-Tooth-Causing HspB1 Mutations using the Rosa26 Locus

Article type: Research Article

Authors: Bouhy, Delphine^a | Geuens, Thomas^a | De Winter, Vicky^a | Almeida-Souza, Leonardo^{a; 1} | Katona, Istvan^b | Weis, Joachim^b | Hochepied, Tino^{c; d} | Goossens, Steven^{d; e} | Haigh, Jody J.^{d; 2} | Janssens, Sophie^{a; f; g} | Timmerman, Vincent^{a; *}

Affiliations: [a] Peripheral Neuropathy Group, VIB Department of Molecular Genetics and Institute Born Bunge, University of Antwerp, Antwerpen, Belgium | [b] Institute of Neuropathology, University Hospital, RWTH Aachen University, Aachen, Germany | [c] Transgenic Mouse Core Facility, VIB Inflammation Research Center, Ghent University, Gent, Belgium | [d] Department for Biomedical Molecular Biology, Ghent University, Gent, Belgium | [e] Unit for Molecular and Cellular Oncology, VIB Inflammation Research Center, Ghent University, Gent, Belgium | [f] Laboratory for Mucosal Immunology and Immunoregulation, VIB Inflammation Research Centre, Ghent University, Gent, Belgium | [g] Department of Internal Medicine, Ghent University, Gent, Belgium

Correspondence: [*] Correspondence to: Prof. Dr. Vincent Timmerman, PhD, Peripheral Neuropathy Group, VIB-DMG, University of Antwerp, Campus Drie Eiken, building V, Universiteitsplein 1, B-2610 Antwerp, Belgium. Tel.: +32 3 265 10 23; Fax: +32 3 265 11 13; E-mail: [email protected].

Note: [1] Present address: MRC Laboratory of Molecular Biology, Cambridge, UK.

Note: [2] Present address: Mammalian Functional Genetics Laboratory, Division of Blood Cancers, Australian Centre for Blood Diseases, Monash University, Melbourne, VIC 3004, Australia.

Abstract: Background: Charcot-Marie-Tooth (CMT) and associated neuropathies, the most common inherited diseases of the peripheral nervous system, remain so far incurable. Three existing murine models of Charcot-Marie-Tooth type 2F (CMT2F) and/or distal hereditary motor neuropathy type IIb (dHMNIIb), caused by mutations in the small heat shock protein B1 gene (HSPB1/HSP27), partially recapitulate the hallmarks of peripheral neuropathy. Because these models overexpress the HSPB1 mutant proteins they differ from the patients’ situation. Objective: To overcome the possible bias induced by overexpression, we generated and characterized a transgenic model in which the wild type or mutant HSPB1 protein was expressed at a moderate, more physiologically relevant level. Methods: We generated a new transgenic mouse model in which a human wild type (hHSPB1WT) or mutant (hHSPB1R127W; hHSPB1P182L) HSPB1 transgene was integrated in the mouse ROSA26 locus. The motor and sensory functions of the mice was assessed at 3, 6, 9, 12 and 18 month. Results: However, the mice expressing the mutant hHSPB1 do not develop motor or sensory deficits and do not show any sign of axonal degeneration, even at late age. Quantitative PCR analyses reveal contrasting tissue-specific expression pattern for the endogenous mouse and exogenous human HSPB1 and show that the ratio of human HSPB1 to the endogenous mouse HspB1 is lower in the sciatic nerve and spinal cord compared to the brain. Conclusion: These results suggest that expressing the transgene at a physiological level using the ROSA26 locus may not be sufficient to model inherited peripheral neuropathies caused by mutation in HSPB1.

Keywords: Peripheral nervous system disease, HSPB1, transgenic mice, ROSA26 locus

DOI: 10.3233/JND-150144

Journal: Journal of Neuromuscular Diseases, vol. 3, no. 2, pp. 183-200, 2016