1. N-Terminomic Changes in Neurons During Excitotoxicity Reveal Proteolytic Events Associated With Synaptic Dysfunctions and Potential Targets for Neuroprotection
- Author
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S. Sadia Ameen, Nane Griem-Krey, Antoine Dufour, M. Iqbal Hossain, Ashfaqul Hoque, Sharelle Sturgeon, Harshal Nandurkar, Dominik F. Draxler, Robert L. Medcalf, Mohd Aizuddin Kamaruddin, Isabelle S. Lucet, Michael G. Leeming, Dazhi Liu, Amardeep Dhillon, Jet Phey Lim, Faiza Basheer, Hong-Jian Zhu, Laita Bokhari, Carli L. Roulston, Prasad N. Paradkar, Oded Kleifeld, Andrew N. Clarkson, Petrine Wellendorph, Giuseppe D. Ciccotosto, Nicholas A. Williamson, Ching-Seng Ang, and Heung-Chin Cheng
- Subjects
Biochemistry & Molecular Biology ,Cells ,1.1 Normal biological development and functioning ,Glutamic Acid ,Biochemistry ,Analytical Chemistry ,Mice ,Underpinning research ,Genetics ,Animals ,2.1 Biological and endogenous factors ,CaM kinase IIa ,CaM kinase IIb ,Aetiology ,Molecular Biology ,Neurons ,Cultured ,Calpain ,Neurosciences ,neuronal death ,synaptic damage ,Rats ,Brain Disorders ,Stroke ,CRMP2 ,proteolytic processing ,Proteolysis ,Neurological ,neuroprotection ,Nervous System Diseases ,calpains ,excitotoxicity ,Src - Abstract
Excitotoxicity, a neuronal death process in neurological disorders such as stroke, is initiated by the overstimulation of ionotropic glutamate receptors. Although dysregulation of proteolytic signaling networks is critical for excitotoxicity, the identity of affected proteins and mechanisms by which they induce neuronal cell death remain unclear. To address this, we used quantitative N-terminomics to identify proteins modified by proteolysis in neurons undergoing excitotoxic cell death. We found that most proteolytically processed proteins in excitotoxic neurons are likely substrates of calpains, including key synaptic regulatory proteins such as CRMP2, doublecortin-like kinase I, Src tyrosine kinase and calmodulin-dependent protein kinase IIβ (CaMKIIβ). Critically, calpain-catalyzed proteolytic processing of these proteins generates stable truncated fragments with altered activities that potentially contribute to neuronal death by perturbing synaptic organization and function. Blocking calpain-mediated proteolysis of one of these proteins, Src, protected against neuronal loss in a rat model of neurotoxicity. Extrapolation of our N-terminomic results led to the discovery that CaMKIIα, an isoform of CaMKIIβ, undergoes differential processing in mouse brains under physiological conditions and during ischemic stroke. In summary, by identifying the neuronal proteins undergoing proteolysis during excitotoxicity, our findings offer new insights into excitotoxic neuronal death mechanisms and reveal potential neuroprotective targets for neurological disorders.
- Published
- 2023