TY - JOUR
T1 - Temporal dependence of cysteine protease activation following excitotoxic hippocampal injury
AU - Berry, J. N.
AU - Sharrett-Field, L. J.
AU - Butler, T. R.
AU - Prendergast, M. A.
PY - 2012/10/11
Y1 - 2012/10/11
N2 - Excitotoxic insults can lead to intracellular signaling cascades that contribute to cell death, in part by activation of proteases, phospholipases, and endonucleases. Cysteine proteases, such as calpains, are calcium (Ca2+)-activated enzymes which degrade cytoskeletal proteins, including microtubule-associated proteins, tubulin, and spectrin, among others. The current study used the organotypic hippocampal slice culture model to examine whether pharmacologic inhibition of cysteine protease activity inhibits N-methyl-D-aspartate- (NMDA-) induced excitotoxic (20μM NMDA) cell death and changes in synaptophysin immunoreactivity. Significant NMDA-induced cytotoxicity (as measured by propidium iodide [PI] uptake) was found in the CA1 region of the hippocampus at all timepoints examined (24, 72, 120h), an effect significantly attenuated by co-exposure to the selective NMDA receptor antagonist DL-2-Amino-5-phosphonopentanoic acid (APV), but not MDL-28170, a potent cysteine protease inhibitor. Results indicated sparing of NMDA-induced loss of the synaptic vesicular protein synaptophysin in all regions of the hippocampus by MDL-28170, though only at early timepoints after injury. These results suggest Ca2+-dependent recruitment of cysteine proteases within 24h of excitotoxic insult, but activation of alternative cellular degrading mechanisms after 24h. Further, these data suggest that synaptophysin may be a substrate for calpains and related proteases.
AB - Excitotoxic insults can lead to intracellular signaling cascades that contribute to cell death, in part by activation of proteases, phospholipases, and endonucleases. Cysteine proteases, such as calpains, are calcium (Ca2+)-activated enzymes which degrade cytoskeletal proteins, including microtubule-associated proteins, tubulin, and spectrin, among others. The current study used the organotypic hippocampal slice culture model to examine whether pharmacologic inhibition of cysteine protease activity inhibits N-methyl-D-aspartate- (NMDA-) induced excitotoxic (20μM NMDA) cell death and changes in synaptophysin immunoreactivity. Significant NMDA-induced cytotoxicity (as measured by propidium iodide [PI] uptake) was found in the CA1 region of the hippocampus at all timepoints examined (24, 72, 120h), an effect significantly attenuated by co-exposure to the selective NMDA receptor antagonist DL-2-Amino-5-phosphonopentanoic acid (APV), but not MDL-28170, a potent cysteine protease inhibitor. Results indicated sparing of NMDA-induced loss of the synaptic vesicular protein synaptophysin in all regions of the hippocampus by MDL-28170, though only at early timepoints after injury. These results suggest Ca2+-dependent recruitment of cysteine proteases within 24h of excitotoxic insult, but activation of alternative cellular degrading mechanisms after 24h. Further, these data suggest that synaptophysin may be a substrate for calpains and related proteases.
KW - Calpain
KW - Cysteine protease
KW - Excitotoxicity
KW - NMDA receptors
KW - Synaptophysin
UR - http://www.scopus.com/inward/record.url?scp=84865644720&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84865644720&partnerID=8YFLogxK
U2 - 10.1016/j.neuroscience.2012.07.033
DO - 10.1016/j.neuroscience.2012.07.033
M3 - Article
C2 - 22842515
AN - SCOPUS:84865644720
SN - 0306-4522
VL - 222
SP - 147
EP - 158
JO - Neuroscience
JF - Neuroscience
ER -