Liu Heling, Nowak Rebecca, Chao Wei, Bloch Kenneth D
Cardiovascular Research Center of the Department of Medicine, Harvard Medical School, Charlestown, Massachusetts, USA.
J Neurochem. 2003 Sep;86(6):1553-63. doi: 10.1046/j.1471-4159.2003.01978.x.
Nerve growth factor (NGF) and heme oxygenases (HOs) both exert neuroprotective effects. To characterize the role of HOs in the prevention of apoptosis by NGF, we investigated the effect of NGF on the expression of HOs in serum-deprived PC12 cells. Serum deprivation (SD) led to a rapid decrease in HO-1 gene expression followed by induction of apoptosis. Incubation of serum-deprived PC12 cells with NGF prevented apoptosis and increased HO-1 mRNA and protein levels, as well as HO enzyme activity. HO-2 gene expression was unaffected by SD or NGF. Incubation of cells with mitogen-activated protein kinase kinase (MEK) inhibitors (PD98059 or U0126) attenuated the ability of NGF to increase HO-1 expression and to protect PC12 cells against SD-induced apoptosis. NGF augmented HO-1 gene transcription but did not alter HO-1 mRNA stability. HO inhibitors or antisense HO-1 RNA decreased the ability of NGF to prevent cell apoptosis. Inhibition of HO activity enhanced intracellular reactive oxygen species (ROS) production and attenuated NGF-induced reduction of ROS in serum-deprived PC12 cells. These results demonstrate that NGF enhances HO-1 gene transcription via MEK activation and that the induction of HO-1 plays an important role in the antioxidative and antiapoptotic effects of NGF in serum-deprived PC12 cells.
神经生长因子（NGF）和血红素加氧酶（HOs）均具有神经保护作用。为了阐明HOs在NGF预防细胞凋亡中的作用，我们研究了NGF对血清剥夺的PC12细胞中HOs表达的影响。血清剥夺（SD）导致HO-1基因表达迅速下降，随后诱导细胞凋亡。用NGF孵育血清剥夺的PC12细胞可预防细胞凋亡，并增加HO-1 mRNA和蛋白水平以及HO酶活性。HO-2基因表达不受SD或NGF的影响。用丝裂原活化蛋白激酶激酶（MEK）抑制剂（PD98059或U0126）孵育细胞可减弱NGF增加HO-1表达以及保护PC12细胞免受SD诱导的细胞凋亡的能力。NGF增强了HO-1基因转录，但未改变HO-1 mRNA的稳定性。HO抑制剂或反义HO-1 RNA降低了NGF预防细胞凋亡的能力。抑制HO活性可增强血清剥夺的PC12细胞内活性氧（ROS）的产生，并减弱NGF诱导的ROS减少。这些结果表明，NGF通过MEK激活增强HO-1基因转录，并且HO-1的诱导在血清剥夺的PC12细胞中NGF的抗氧化和抗凋亡作用中起重要作用。
