Calpain cleavage of collapsin response mediator proteins in ischemic mouse brain

Authors

  • Susan X. Jiang,

    1. Experimental NeuroTherapeutics Laboratory and NRC Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Building M54, Ottawa, ON, Canada, K1A 0R6
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  • Joachim Kappler,

    1. Institut für Physiologische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
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  • Bogdan Zurakowski,

    1. Animal Facility, NRC Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON, Canada
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  • Angele Desbois,

    1. Experimental NeuroTherapeutics Laboratory and NRC Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Building M54, Ottawa, ON, Canada, K1A 0R6
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  • Amy Aylsworth,

    1. Experimental NeuroTherapeutics Laboratory and NRC Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Building M54, Ottawa, ON, Canada, K1A 0R6
    2. Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON, Canada
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  • Sheng T. Hou

    1. Experimental NeuroTherapeutics Laboratory and NRC Institute for Biological Sciences, National Research Council of Canada, 1200 Montreal Road, Building M54, Ottawa, ON, Canada, K1A 0R6
    2. Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON, Canada
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Dr Sheng T. Hou, 1Experimental NeuroTherapeutics Laboratory, as above.
E-mail: sheng.hou@nrc-cnrc.gc.ca

Abstract

Collapsin response mediator proteins (CRMPs) are important brain-specific proteins with distinct functions in modulating growth cone collapse and axonal guidance during brain development. Our previous studies have shown that calpain cleaves CRMP3 in the adult mouse brain during cerebral ischemia [S.T. Hou et al. (2006) J. Neurosci., 26, 2241–2249]. Here, the expression of all CRMP family members (1–5) was examined in mouse brains that were subjected to middle cerebral artery occlusion. Among the five CRMPs, the expressions of CRMP1, CRMP3 and CRMP5 were the most abundant in the cerebral cortex and all CRMPs were targeted for cleavage by ischemia-activated calpain. Sub-cellular fractionation analysis showed that cleavage of CRMPs by calpain occurred not only in the cytoplasm but also in the synaptosomes isolated from ischemic brains. Moreover, synaptosomal CRMPs appeared to be at least one-fold more sensitive to cleavage compared with those isolated from the cytosolic fraction in an in-vitro experiment, suggesting that synaptosomal CRMPs are critical targets during cerebral ischemia-induced neuronal injury. Finally, the expression of all CRMPs was colocalized with TUNEL-positive neurons in the ischemic mouse brain, which further supports the notion that CRMPs may play an important role in neuronal death following cerebral ischemia. Collectively, these studies demonstrated that CRMPs are targets of calpains during cerebral ischemia and they also highlighted an important potential role that CRMPs may play in modulating ischemic neuronal death.

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