[NRH2 induces cell apoptosis of cerebral tissues around hematomas after intracerebral hemorrhage through up-regulating proNGF, sortilin and p75NTR expressions].
[NRH2 induces cell apoptosis of cerebral tissues around hematomas after intracerebral hemorrhage through up-regulating proNGF, sortilin and p75NTR expressions].
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发表时间：
2015-04
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通讯作者：
Zhiqing Zeng;Hong Liu;D. Jiang
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作者：
Zhiqing Zeng;Hong Liu;D. Jiang
目的观察脑出血后不同时期血肿周围脑组织中神经营养素受体同源物2（NRH 2）、神经生长因子前体（proNGF）、分拣蛋白（sortilin）和神经营养素受体p75（p75 NTR）的表达，探讨其与细胞凋亡的关系。方法收集脑出血血肿清除术患者血肿周围脑组织标本。根据脑出血至标本采集的时间分为≤ 6 h、6-24 h（含24 h）、24-72 h（含72 h）和> 72 h 4组。同时取术中脱落的10例远离出血部位的脑组织作为对照组。采用末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记法（TUNEL）检测脑细胞凋亡指数（AI）。采用实时荧光定量PCR和Western blotting方法分别检测脑组织中NRH 2、proNGF、sortilin和p75 NTR mRNA和蛋白的表达。Western blotting检测脑组织Bcl-2和Bax的表达。体外培养大鼠皮层星形胶质细胞，转染NRH 2 siRNA和scramble siRNA。Western blotting检测proNGF、sortilin和p75 NTR蛋白的表达。结果脑出血6 h及以上各组AI均高于对照组和≤ 6 h组，以出血后24-72 h组AI最高。而≤ 6 h组AI与对照组相比差异无统计学意义。随着脑出血时间的延长，proNGF和p75 NTR mRNA及蛋白表达水平逐渐升高，在24-72 h达到高峰，72 h后仍维持较高水平，而≤ 6 h组与对照组相比上述指标无显著性差异。与对照组和≤ 6 h组相比，NRH 2、sortilin mRNA和蛋白表达水平及Bax表达水平在6-24 h开始升高，24-72 h达到高峰，72 h后维持较高水平，而≤ 6 h组与对照组相比上述指标无显著性差异。Bcl-2表达水平在≤ 6 h组与对照组比较无明显变化。脑出血后6 h以上各组Bcl-2水平均下降，24-72 h达最低值。转染NRH 2 siRNA的星形胶质细胞proNGF、sortilin和p75 NTR蛋白表达水平较scramble siRNA组和空白对照组显著降低。结论脑出血后血肿周围脑组织中NRH 2表达增加。NRH 2可能通过促进proNGF、sortilin和p75 NTR的表达，提高Bax/Bcl-2比值，从而诱导脑细胞凋亡。
OBJECTIVE To observe the expressions of neurotrophin receptor homolog 2 (NRH2), nerve growth factor precursor (proNGF), sortilin and neurotrophin receptor p75 (p75NTR) in cerebral tissues around hematomas in the different periods after intracerebral hemorrhage, and explore their relationships to cell apoptosis. METHODS The specimens of cerebral tissues around hematomas were collected from the patients undergoing hematoma removal operation after intracerebral hemorrhage. These specimens were divided into four groups, namely ≤ 6 hours, 6-24 hours(including 24 hours), 24-72 hours (including 72 hours) and over 72 hours according to the time from intracerebral hemorrhage to specimen collection. At the same time, 10 brain tissues distant to hemorrhage that dropped in the operative process were collected as a control group. Apoptosis index (AI) was examined in brain cells by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL). The expressions of NRH2, proNGF, sortilin and p75NTR mRNAs and proteins in brain tissues were detected through real-time quantitative PCR and Western blotting, respectively. Also, the expressions of Bcl-2 and Bax in brain tissues were analyzed using Western blotting. In vitro cultured astrocytes of rat cortex were transfected by NRH2 siRNA or scramble siRNA. The expressions of proNGF, sortilin and p75NTR proteins were detected using Western blotting. RESULTS AI was higher in all groups of hemorrhage for 6 hours or longer than that in control and ≤ 6 hours groups, and AI in the group of 24-72 hours after intracerebral hemorrhage was the highest. However, there was no significant difference in AI between ≤ 6 hours group and control group. With the extension of intracerebral hemorrhage time, the expression levels of proNGF and p75NTR mRNAs and proteins were gradually elevated, reached the peak in 24-72 hours, and maintained a higher level after 72 hours, whereas there were no significant differences in the above indicators between ≤ 6 hours group and control group. In comparison with control group and ≤ 6 hours group, the expression levels of NRH2 and sortilin mRNAs and proteins and Bax expression started to increase in 6-24 hours, reached the peak in 24-72 hours, and then stayed a higher level after 72 hours, whereas there were no significant differences in the above indicators between ≤ 6 hours group and control group. There was no obvious change in Bcl-2 expression level between ≤ 6 hours group and control group. The level of Bcl-2 decreased in all groups of intracerebral hemorrhage for over 6 hours, and reached the nadir in 24-72 hours. Astrocytes transfected with NRH2 siRNA displayed a significant decrease in proNGF, sortilin and p75NTR protein levels as compared with scramble siRNA or blank control groups. CONCLUSION The expression of NRH2 would increase in the cerebral tissues around hematomas after intracerebral hemorrhage. NRH2 might enhance the ratio of Bax/Bcl-2 by promoting the expressions of proNGF, sortilin and p75NTR, thereby inducing brain cell apoptosis.