Chang Alice Y W, Chan Julie Y H, Chou Jimmy L J, Li Faith C H, Dai Kuang-Yu, Chan Samuel H H
Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, Taiwan, Republic of China.
J Physiol. 2006 Jul 15;574(Pt 2):547-64. doi: 10.1113/jphysiol.2006.110890. Epub 2006 May 4.
The rostral ventrolateral medulla (RVLM) is the origin of a 'life-and-death' signal that reflects central cardiovascular regulatory failure during brain stem death. Using an experimental endotoxaemia model, we evaluated the hypothesis that the 60 kDa heat shock protein 60 (HSP60) reduces cardiovascular fatality during brain stem death via an anti-apoptotic action in the RVLM. In Sprague-Dawley rats maintained under propofol anaesthesia, proteomic or Western blot analysis revealed a progressive augmentation of HSP60 expression in the RVLM after intravenous administration of Escherichia coli lipopolysaccharide (30 mg kg(-1)). Pretreatment with a microinjection of actinomycin D or cycloheximide into bilateral RVLM significantly blunted this HSP60 increase, whereas real-time PCR showed progressive augmentation of hsp60 mRNA. Intriguingly, superimposed on the augmented expression was a progressive decline in mitochondrial, or elevation in cytosolic, HSP60 in ventrolateral medulla. Loss-of-function manipulations in the RVLM using anti-HSP60 antiserum or antisense hsp60 oligonucleotide exacerbated mortality by potentiating the cardiovascular depression during experimental endotoxaemia, alongside intensified nucleosomal DNA fragmentation, elevated cytoplasmic histone-associated DNA fragments or augmented cytochromec-caspase-3 cascade of apoptotic signalling in the RVLM. Immunoprecipitation coupled with immunoblot analysis further revealed a progressive increase in the complex formed between HSP60 and mitochondrial or cytosolic Bax or mitochondrial Bcl-2 during endotoxaemia, alongside a dissociation of the cytosolic HSP60-Bcl-2 complex. We conclude that HSP60 redistributed from mitochondrion to cytosol in the RVLM confers neuroprotection against fatal cardiovascular depression during endotoxaemia via reduced activation of the cytochrome c-caspase-3 cascade of apoptotic signalling through enhanced interactions with mitochondrial or cytosolic Bax or Bcl-2.
延髓头端腹外侧区（RVLM）是一种“生死”信号的起源，该信号反映脑干死亡期间的中枢心血管调节功能衰竭。我们使用实验性内毒素血症模型，评估了60 kDa热休克蛋白60（HSP60）通过在RVLM中的抗凋亡作用降低脑干死亡期间心血管死亡风险的假说。在丙泊酚麻醉下的Sprague-Dawley大鼠中，蛋白质组学或蛋白质印迹分析显示，静脉注射大肠杆菌脂多糖（30 mg kg⁻¹）后，RVLM中HSP60的表达逐渐增加。向双侧RVLM微量注射放线菌素D或环己酰亚胺进行预处理可显著抑制这种HSP60的增加，而实时PCR显示hsp60 mRNA逐渐增加。有趣的是，在表达增加的同时，腹外侧延髓中线粒体HSP60逐渐减少或胞质HSP60升高。使用抗HSP60抗血清或反义hsp60寡核苷酸对RVLM进行功能丧失操作，通过增强实验性内毒素血症期间的心血管抑制作用，加剧了死亡率，同时RVLM中核小体DNA片段化加剧、细胞质组蛋白相关DNA片段升高或凋亡信号的细胞色素c-半胱天冬酶-3级联增强。免疫沉淀结合免疫印迹分析进一步显示，内毒素血症期间HSP60与线粒体或胞质Bax或线粒体Bcl-2之间形成的复合物逐渐增加，同时胞质HSP60-Bcl-2复合物解离。我们得出结论，RVLM中HSP60从线粒体重新分布到细胞质，通过增强与线粒体或胞质Bax或Bcl-2的相互作用，减少凋亡信号的细胞色素c-半胱天冬酶-3级联的激活，从而对内毒素血症期间致命的心血管抑制提供神经保护。
