Heat shock protein 27 rescues motor neurons following nerve injury and preserves muscle function.
Heat shock proteins (HSPs) are a family of ubiquitously expressed proteins that are up-regulated in response to a range of stresses and play an important role in cellular defence mechanisms. In previous studies, we demonstrated that overexpression of heat shock protein 27 (HSP27) in transgenic mice has significant cytoprotective properties in vivo, reducing caspase-3-mediated cell death in the hippocampus associated with limbic seizures and reducing infarct size in cardiac ischaemia. In motor neurons, HSP27 is also implicated as a survival promoting factor; however, it remains to be established whether HSP27 is able to exert long-term neuroprotective effects following neonatal nerve injury. We now show that, following neonatal nerve crush, HSP27 overexpression in vivo provides a substantial rescue of motor neurons 5-6 months following nerve injury. Furthermore, in vivo isometric tension recordings demonstrate that surviving motor neurons were able to regenerate, resulting in a 90% improvement (P < 0.0005) in motor unit number in HSP27 mice. Moreover, this increase in motor unit number was associated with improved muscle weight, muscle force, contractile speeds, and histochemical markers of muscle activity. These properties of HSP27 therefore have considerable potential for improving long-term muscle function in motor neuron disorders.
Sharp
Paul
P
Department of Cellular and Molecular Neuroscience, Division of Neuroscience and Mental Health, Faculty of Medicine, Imperial College London, Charing Cross Hospital Campus, Fulham Palace Road, London W6 8RF, UK.
Krishnan
Michelle
M
Pullar
Oliver
O
Navarrete
Roberto
R
Wells
Dominic
D
de Belleroche
Jacqueline
J
D000818:Animals; D000831:Animals, Newborn; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000235:genetics; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000254:growth & development / Q000503:physiopathology; D009409:Nerve Crush / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D020127:Recovery of Function / Q000235:genetics*; D020426:Sciatic Neuropathy / Q000473:pathology / Q000503:physiopathology*
D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486699:Hspb2 protein, mouse; D002795:Choline O-Acetyltransferase