Significance and molecular targets of protein kinase A during cAMP-mediated protection of cold stored liver grafts
Significance and molecular targets of protein kinase A during cAMP-mediated protection of cold stored liver grafts
复制标题
DOI：
10.1007/pl00000808
复制
发表时间：
2001-10-01
影响因子：
8
通讯作者：
Minor, T
中科院分区：
文献类型：
--
作者：
Akbar, S;Minor, T
使用边缘供体肝脏后，移植后原发性功能障碍或无功能发生率较高。为验证激活cAMP第二信使信号通路可能保护肝脏免受缺血性损伤的假说，本研究着重于蛋白激酶A介导的信号转导作用。肝脏的完整性进行了评估，此后使用无血再灌注model.Supplementation的保存液与二丁酰-cAMP（db-cAMP）促进磷酸化的BAD在Ser 112，并伴随着减轻线粒体释放细胞色素c到胞质溶胶。凋亡细胞转化是明显的再灌注肝脏阳性TUNEL染色的窦衬里细胞和切割的聚（ADP-核糖）聚合酶（PAR-P）的组织匀浆中的检测，通过Western分析。用db-cAMP治疗有效地最大限度地减少TUNEL染色和PARP裂解，并将丙氨酸氨基转移酶的缺血后酶泄漏显著减少至一半，而与未治疗的肝脏相比，肝脏胆汁产生增加了约60%。这种功能改善伴随着门静脉血管传导性的净改善。抑制A激酶锚定蛋白与HT 31完全逆转任何所观察到的效果获得DB-cAMP。我们得出结论，增强细胞cAMP信号保持肝脏的完整性，在缺血保存期间和之后，这可能是由于蛋白激酶A依赖磷酸化BAD在随后的抑制BAD启动的细胞凋亡的窦状隙衬里细胞。
The use of marginal donor livers is followed by a higher frequency of primary dys- or nonfunction after transplantation. The present study was designed to test the hypothesis that stimulation of the cAMP second-messenger signal pathway might protect the liver from ischemic injury, laying emphasis on the role of protein kinase A-mediated signal transduction.Rat livers were harvested after 45 min of cardiac arrest and preserved in HTK solution for 24 h. Hepatic integrity was assessed thereafter using a blood-free reperfusion model.Supplementation of the preservation solution with dibutyryl-cAMP (db-cAMP) promoted phosphorylation of BAD at Ser 112 and concomitantly mitigated mitochondrial release of cytochrome c into the cytosol. Apoptotic cell transformation was evident in reperfused livers by positive TUNEL-staining of sinusoidal lining cells and the detection of cleaved poly(ADP-ribose) polymerase (PAR-P) in tissue homogenates, by western analysis. Treatment with db-cAMP was effective in minimizing both TUNEL staining and PARP cleavage and significantly reduced postischemic enzyme leakage of alanine aminotransferase to one half, while hepatic bile production was enhanced by approximately 60% when compared to untreated livers. This functional improvement was accompanied by a net amelioration of portal vascular conductivity. Inhibition of A kinase-anchoring protein with HT31 completely reversed any of the observed effects obtained by db-cAMP.We conclude that enhancement of cellular cAMP signal maintains hepatic integrity during and after ischemic preservation which may be attributed to protein kinase A dependent phosphorylation of BAD in line with subsequent inhibition of mitochondria-initiated apoptosis of sinusoidal lining cells.