title: Critical role of calpain in spinal cord degeneration in Parkinson's disease.
abstract: While multiple molecular mechanisms contribute to midbrain nigrostriatal dopaminergic degeneration in Parkinson's disease (PD), the mechanism of damage in non-dopaminergic sites within the central nervous system, including the spinal cord, is not well-understood. Thus, to understand the comprehensive pathophysiology underlying this devastating disease, postmortem spinal cord tissue samples (cervical, thoracic, and lumbar segments) from patients with PD were analyzed compared to age-matched normal subjects or Alzheimer's disease for selective molecular markers of neurodegeneration and inflammation. Distal axonal degeneration, relative abundance of both sensory and motor neuron death, selective loss of ChAT(+) motoneurons, reactive astrogliosis, microgliosis, increased cycloxygenase-2 (Cox-2) expression, and infiltration of T cells were observed in spinal cord of PD patients compared to normal subjects. Biochemical analyses of spinal cord tissues revealed associated inflammatory and proteolytic events (elevated levels of Cox-2, expression and activity of μ- and m-calpain, degradation of axonal neurofilament protein, and concomitantly low levels of endogenous inhibitor - calpastatin) in spinal cord of PD patients. Thus, pathologically upregulated calpain activity in spinal cords of patients with PD may contribute to inflammatory response-mediated neuronal death, leading to motor dysfunction. We proposed calpain over-activation and calpain-calpastatin dysregulation driving in a cascade of inflammatory responses (microglial activation and T cell infiltration) and degenerative pathways culminating in axonal degeneration and neuronal death in spinal cord of Parkinson's disease patients. This may be one of the crucial mechanisms in the degenerative process.
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Suite 309 CSB, P.O. Box 250606, Charleston, SC, 29425, USA.
authors.forename: Supriti
authors.initials: S
authors.lastname: Samantaray
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Suite 309 CSB, P.O. Box 250606, Charleston, SC, 29425, USA.
authors.forename: Varduhi H
authors.initials: VH
authors.lastname: Knaryan
authors.affiliation: Department of Neurosurgery, The George Washington University, 2150 Pennsylvania Avenue, NW, Suite 7-420, Washington, DC, 20037, USA.
authors.forename: Donald C
authors.initials: DC
authors.lastname: Shields
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Suite 309 CSB, P.O. Box 250606, Charleston, SC, 29425, USA.
authors.forename: Naren L
authors.initials: NL
authors.lastname: Banik
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology / Q000473:pathology; D001369:Axons / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D016022:Case-Control Studies; D016923:Cell Death; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005911:Gliosis; D006801:Humans; D006816:Huntington Disease / Q000201:enzymology / Q000473:pathology; D007249:Inflammation / Q000276:immunology; D009103:Multiple Sclerosis / Q000201:enzymology / Q000473:pathology; D009410:Nerve Degeneration / Q000201:enzymology* / Q000473:pathology; D009474:Neurons / Q000473:pathology; D010300:Parkinson Disease / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D013116:Spinal Cord / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; C033668:calpastatin; D002154:Calpain
keywords: axonal degeneration; calpain; inflammation; neurodegeneration