Human Biliverdin Reductase, a Previously Unknown Activator of Protein Kinase C βII*
Human Biliverdin Reductase, a Previously Unknown Activator of Protein Kinase C βII*
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人胆绿素还原酶，一种以前未知的蛋白激酶 C βII* 激活剂
DOI：
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发表时间：
2007
影响因子：
4.8
通讯作者：
P. E. Gibbs
中科院分区：
文献类型：
--
作者：
M. Maines;T. Miralem;N. Lerner‐Marmarosh;Jenny Shen;P. E. Gibbs
人胆绿素还原酶(HBVR)是一种由胰岛素和自由基(Miralem，T.，Hu，Z.，Torno，M.D.，Lelli，K.M.和Maines，M.D.，Lelli，K.M.和Maines，M.D.(2005)J.Biol)激活的双特异性蛋白激酶，如蛋白激酶C(PKC)βII。化学。17084-17092；Lerner-Marmarosh，N.，Shen.J.，Torno，M.D.，Kravets，A.，Hu，Z.和Maines，M.D.(2005年)Proc.娜塔莉。阿卡德。SCI。美国102,7109-7114)。在此，我们利用共转染293A细胞的pc DNA3-hBVR和PKCβII，我们报道了谷胱甘肽S转移酶下拉实验中两种蛋白的免疫共沉淀和共纯化。HBVR和PKCβII，而不是还原酶和PKCζ，在只支持其中一种酶活性的检测系统中被转磷酸化。PKCβII K371R突变蛋白(“KK-DEAD”)也是hBVR的底物。该还原酶增加了髓鞘碱性蛋白PKCβII的Vmax，但不增加表观Km值；激活不依赖于磷脂，并延伸到PKC特异性底物S2的磷酸化。底物磷酸化的增加可被常规PKC的特异性抑制剂阻断，并被sihBVR减弱。后者的作用可以通过随后hBVR的过表达来挽救。在很大程度上，这种激活是由hBVR的Valine N-末端链、完整的ATP结合位点和富含半胱氨酸的C-末端片段决定的。钴原卟啉激活的hBVR磷酸化了人PKCβII激活环中与Thr500相对应的多肽中的一个苏氨酸。与PKCβII的其他磷酸化位点对应的多肽中的丝氨酸和苏氨酸残基都不是底物，也不是PKCζ激活环源性多肽的底物。HBVR·PKCβII免疫复合物免疫印迹证实Thr500被磷酸化。HBVR激活PKCβII的潜在生物学意义在于，在转染PKCβII的细胞中，hBVR增强了佛波酯介导的c-fos表达，而感染sihBVR则减弱了这一反应。此外，在高表达hBVR和PKCβII的细胞中，以及在未转染的细胞中，经佛波酯处理后，PKC移位到质膜并与hBVR共定位。HBVR激活PKCβII突显了其在通过PKC传递的信号传播中的潜在功能。
Human biliverdin reductase (hBVR), a dual specificity kinase (Ser/Thr/Tyr) is, as protein kinase C (PKC) βII, activated by insulin and free radicals (Miralem, T., Hu, Z., Torno, M. D., Lelli, K. M., and Maines, M. D. (2005) J. Biol. Chem. 280, 17084–17092; Lerner-Marmarosh, N., Shen, J., Torno, M. D., Kravets, A., Hu, Z., and Maines, M. D. (2005) Proc. Natl. Acad. Sci. U. S. A. 102, 7109–7114). Here, by using 293A cells co-transfected with pcDNA3-hBVR and PKC βII plasmids, we report the co-immunoprecipitation of the proteins and co-purification in the glutathione S-transferase (GST) pulldown assay. hBVR and PKC βII, but not the reductase and PKC ζ, transphosphorylated in assay systems supportive of activity of only one of the kinases. PKC βII K371R mutant protein (“kinase-dead”) was also a substrate for hBVR. The reductase increased the Vmax but not the apparent Km values of PKC βII for myelin basic protein; activation was independent of phospholipids and extended to the phosphorylation of S2, a PKC-specific substrate. The increase in substrate phosphorylation was blocked by specific inhibitors of conventional PKCs and attenuated by sihBVR. The effect of the latter could be rescued by subsequent overexpression of hBVR. To a large extent, the activation was a function of the hBVR N-terminal chain of valines and intact ATP-binding site and the cysteine-rich C-terminal segment. The cobalt protoporphyrin-activated hBVR phosphorylated a threonine in a peptide corresponding to the Thr500 in the human PKC βII activation loop. Neither serine nor threonine residues in peptides corresponding to other phosphorylation sites of the PKC βII nor PKC ζ activation loop-derived peptides were substrates. The phosphorylation of Thr500 was confirmed by immunoblotting of hBVR·PKC βII immunocomplex. The potential biological relevance of the hBVR activation of PKC βII was suggested by the finding that in cells transfected with the PKC βII, hBVR augmented phorbol myristate acetate-mediated c-fos expression, and infection with sihBVR attenuated the response. Also, in cells overexpressing hBVR and PKC βII, as well as in untransfected cells, upon treatment with phorbol myristate acetate, the PKC translocated to the plasma membrane and co-localized with hBVR. hBVR activation of PKC βII underscores its potential function in propagation of signals relayed through PKCs.
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DOI：
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发表时间：
2001
期刊：
The Journal of pharmacology and experimental therapeutics
影响因子：
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影响因子：
56.9
作者：
MOCHLYROSEN, D
通讯作者：
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DOI：
10.1111/j.1432-1033.1996.00372.x
发表时间：
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期刊：
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影响因子：
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DOI：
10.1073/pnas.0502173102
发表时间：
2005-05-17
影响因子：
11.1
作者：
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通讯作者：
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