Increased expression of apoptosis-linked gene 2 (ALG2) in the rat brain after temporary focal cerebral ischemia

Calcium is an important mediator of programmed cell death induced by transi ent cerebral ischemia, and calcium-binding proteins have been implicated in calcium-regulated signal transduction. Apoptosis-linked gene 2 is a calciu m-binding protein required for cell death induced by different apoptotic st imuli. By Western blot analysis, we found that apoptosis-linked gene 2 prot ein was expressed in normal brains, and that expression increased in ischem ic brains after 20 or 90 min of transient focal cerebral ischemia. Immunocy tochemistry showed increased apoptosis-linked gene 2 protein expression in frontal cortex, a region where neurons underwent ischemic stress but still survived, after 20 or 90 min of focal cerebral ischemia. Apoptosis-linked g ene 2 protein was also up-regulated in the ischemic border-zone of parietal cortex 24 h after 20 min of focal ischemia, and was remarkably over-expres sed in the caudate-putamen and parietal cortex, (where cells are destined t o die) 24 h after 90 min of ischemia. The expression pattern of apoptosis-l inked gene 2 protein was similar to that of deoxyribonucleic acid damage de tected by Klenow labeling assay. Our results suggest that apoptosis-linked gene 2 may be involved in the reg ulation of cell death after transient focal cerebral ischemia. (C) 2000 IBR O. Published by Elsevier Science Ltd.