J Biol Chem, Vol. 274, Issue 40, 28674-28681, October 1, 1999
Rat B2 Sequences Are Induced in the Hippocampal CA1
Region After Transient Global Cerebral Ischemia
Xiaodong
Liu,
James A.
Clemens,
Tinggui
Yin,
Diane T.
Stephenson,
Edward M.
Johnstone,
Yansheng
Du,
Jill A.
Panetta,
Steven
M.
Paul, and
Sheila P.
Little
From the Neuroscience Research Division, Eli Lilly and Company,
Indianapolis, Indiana 46285
Global brain ischemia causes cell death in the
CA1 region of the hippocampus 3-5 days after reperfusion. The
biological pathway leading to such delayed neuronal damage has not been
established. By using differential display analysis, we examined
expression levels of poly(A) RNAs isolated from hippocampal extracts
prepared from rats exposed to global ischemia and found an up-regulated transcript, clone 17a. Northern blot analysis of clone 17a showed an
approximately 35-fold increase in the ischemic brain at 24 h after
four-vessel occlusion. Rapid amplification of cDNA ends of clone
17a revealed a family of genes (160-540 base pairs) that had the
characteristics of rodent B2 sequences. In
situ hybridization demonstrated that the elevated expression of
this gene was localized predominantly in the CA1 pyramidal neurons. The
level of expression in the CA1 region decreased dramatically between 24 and 72 h after ischemia. The elevated expression of clone 17a was
not observed in four-vessel occlusion rats treated with the compound
LY231617, an antioxidant known to exert neuroprotection in rats
subjected to global ischemia. Since delayed neuronal death has the
characteristics of apoptosis, we speculate that clone 17a may be
involved in apoptosis. We examined the expression level of clone 17a in
in vitro models of apoptosis using cerebellar granule
neurons that were subjected to potassium removal, glutamate toxicity,
or 6-hydroxydopamine treatment and found that clone 17a transcripts
were induced in cerebellar granule neurons by glutamate or
6-hydroxydopamine stimulation but not potassium withdrawal.
Copyright © 1999 by The American Society for Biochemistry and Molecular Biology, Inc.