TY - JOUR
T1 - Expression of poly(C)-binding proteins is differentially regulated by hypoxia and ischemia in cortical neurons
AU - Zhu, Y.
AU - Sun, Y.
AU - Mao, X. O.
AU - Jin, K. L.
AU - Greenberg, D. A.
N1 - Funding Information:
We thank R. Andino for providing anti-PCBP1 and anti-PCBP2 antibodies. This work was supported by National Institutes of Health Grant NS35965.
PY - 2002/3/12
Y1 - 2002/3/12
N2 - Hypoxia and ischemia regulate the expression of several important genes at the level of transcription and of mRNA stability. Two isoforms of a 40-kDa poly(C)-binding protein, previously identified as RNA-binding proteins, bind to a hypoxia-inducible protein-binding site in the 3′-untranslated region of erythropoietin and tyrosine hydroxylase mRNAs and regulate mRNA stability. To determine if poly(C)-binding proteins show changes in expression - which might regulate mRNA stability - in hypoxic or ischemic neuronal cells, we examined poly(C)-binding protein 1 and poly(C)-binding protein 2 expression in hypoxic cortical neuron cultures and in rat cerebral cortex after focal ischemia. Reverse transcription-polymerase chain reaction and western blotting showed hypoxic up-regulation of poly(C)-binding protein 1, and down-regulation of poly(C)-binding protein 2, mRNA and protein expression. Hypoxia-inducible expression of poly(C)-binding protein 1 was mediated by p38 mitogen-activated protein kinase, while hypoxia-reducible expression of poly(C)-binding protein 2 was mediated by protein kinase C. Immunostaining showed that poly(C)-binding protein 1, but not poly(C)-binding protein 2, expression was increased in the ischemic boundary zone (penumbra) of the frontal cortex after 90 min of ischemia, and persisted for at least 72 h after reperfusion. These results demonstrate that poly(C)-binding protein 1 and poly(C)-binding protein 2 in cortical neurons are differentially affected by hypoxic/ischemic insults, suggesting that there are functional differences between poly(C)-binding protein isoforms. Since we observed no poly(C)-binding protein expression in astroglia, alternative mRNA stability mechanisms may exist in these cells.
AB - Hypoxia and ischemia regulate the expression of several important genes at the level of transcription and of mRNA stability. Two isoforms of a 40-kDa poly(C)-binding protein, previously identified as RNA-binding proteins, bind to a hypoxia-inducible protein-binding site in the 3′-untranslated region of erythropoietin and tyrosine hydroxylase mRNAs and regulate mRNA stability. To determine if poly(C)-binding proteins show changes in expression - which might regulate mRNA stability - in hypoxic or ischemic neuronal cells, we examined poly(C)-binding protein 1 and poly(C)-binding protein 2 expression in hypoxic cortical neuron cultures and in rat cerebral cortex after focal ischemia. Reverse transcription-polymerase chain reaction and western blotting showed hypoxic up-regulation of poly(C)-binding protein 1, and down-regulation of poly(C)-binding protein 2, mRNA and protein expression. Hypoxia-inducible expression of poly(C)-binding protein 1 was mediated by p38 mitogen-activated protein kinase, while hypoxia-reducible expression of poly(C)-binding protein 2 was mediated by protein kinase C. Immunostaining showed that poly(C)-binding protein 1, but not poly(C)-binding protein 2, expression was increased in the ischemic boundary zone (penumbra) of the frontal cortex after 90 min of ischemia, and persisted for at least 72 h after reperfusion. These results demonstrate that poly(C)-binding protein 1 and poly(C)-binding protein 2 in cortical neurons are differentially affected by hypoxic/ischemic insults, suggesting that there are functional differences between poly(C)-binding protein isoforms. Since we observed no poly(C)-binding protein expression in astroglia, alternative mRNA stability mechanisms may exist in these cells.
UR - http://www.scopus.com/inward/record.url?scp=0037066071&partnerID=8YFLogxK
U2 - 10.1016/S0306-4522(01)00522-X
DO - 10.1016/S0306-4522(01)00522-X
M3 - Article
C2 - 11958862
AN - SCOPUS:0037066071
SN - 0306-4522
VL - 110
SP - 191
EP - 198
JO - Neuroscience
JF - Neuroscience
IS - 2
ER -