Tumor promoter benzoyl peroxide induces sulfhydryl oxidation in protein kinase C: its reversibility is related to the cellular resistance to peroxide-induced cytotoxicity.
Tumor promoter benzoyl peroxide induces sulfhydryl oxidation in protein kinase C: its reversibility is related to the cellular resistance to peroxide-induced cytotoxicity.
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肿瘤促进剂过氧化苯甲酰诱导蛋白激酶C中的巯基氧化：其可逆性与细胞对过氧化物诱导的细胞毒性的抵抗力有关。
DOI：
10.1006/abbi.1999.1100
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Slaga,TJ
中科院分区：
文献类型：
--
作者：
Gopalakrishna,R;Gundimeda,U;Anderson,WB;Colburn,NH;Slaga,TJ
由于肿瘤促进剂过氧化苯甲酰（BPO）在某些方面模拟佛波醇酯，因此先前研究了其对蛋白激酶C（PKC）的影响。然而，在这些研究中，由于在PKC制剂中存在巯基试剂，未观察到BPO与PKC中氧化还原活性半胱氨酸残基的敏感反应。在这项研究中，通过排除纯化的PKC制剂中存在的硫醇试剂，低浓度的BPO修饰了PKC，导致激酶活性和佛波酯结合的丧失（IC 50 = 0.2至0.5 μM）。这种不依赖于过渡金属的修饰完全被包括GSH在内的各种巯基试剂所阻断，所述巯基试剂直接与BPO反应。亚化学计量量的BPO（0.4 mol/mol的PKC）氧化PKC中的两个巯基并使酶失活，该酶很容易被二硫苏糖醇逆转。具有支持膜插入区的硫醇锌结构的调节结构域提供了PKC与BPO反应的特异性，BPO分配到膜中。与H_2O_2不同，BPO不诱导产生不依赖于Ca ~（2+）/脂质的PKC活化形式。其他氧化还原敏感酶，如蛋白激酶A，磷酸化酶激酶和蛋白磷酸酶2A需要近25至100倍的BPO浓度灭活。BPO还使多种细胞类型中的PKC失活。在JB 6（30 P−）非促进细胞系和其他正常细胞系中，BPO的细胞毒性更强，由于细胞的失活可逆性缓慢，它很容易使PKC失活。然而，在JB 6（41 P+）可促进的细胞系，C3 H10 T1/2和B16黑色素瘤细胞，其中BPO的细胞毒性较低，它不容易使PKC由于这种失活的内源性机制的快速可逆性。然而，BPO在所有这些细胞类型制备的匀浆中以相同的速率灭活PKC。包括NADPH逆转这种失活的匀浆在不同程度上，大概是由于分布的蛋白质二硫键还原酶，逆转这种氧化修饰的差异。BPO诱导的PKC修饰发生的GSH的细胞状态无关。然而，外部添加的GSH和细胞不可渗透的巯基剂阻止了BPO诱导的PKC修饰。由于BPO易于分配到膜中，其与膜蛋白（如PKC）的氧化还原循环硫醇的反应可能引发表观遗传事件以防止细胞毒性，但有利于肿瘤促进。
Since tumor promoter benzoyl peroxide (BPO) mimics phorbol esters in some aspects, its effects on protein kinase C (PKC) were previously studied. However, in those studies due to the presence of thiol agents in the PKC preparations, the sensitive reaction of BPO with redox-active cysteine residues in PKC was not observed. In this study, by excluding thiol agents present in the purified PKC preparation, low concentrations of BPO modified PKC, resulting in the loss of both kinase activity and phorbol ester binding (IC50= 0.2 to 0.5 μM). This modification, which was not dependent on transition metals, was totally blocked by a variety of thiol agents including GSH, which directly reacted with BPO. Substoichiometric amounts of BPO (0.4 mol/mol of PKC) oxidized two sulfhydryls in PKC and inactivated the enzyme which was readily reversed by dithiothreitol. The regulatory domain having zinc thiolate structures supporting the membrane-inserting region provided the specificity for PKC reaction with BPO, which partitioned into the membrane. Unlike H2O2, BPO did not induce the generation of the Ca2+/lipid-independent activated form of PKC. Other redox-sensitive enzymes such as protein kinase A, phosphorylase kinase, and protein phosphatase 2A required nearly 25- to 100-fold higher concentrations of BPO for inactivation. BPO also inactivated PKC in a variety of cell types. In the JB6 (30 P−) nonpromotable cell line and other normal cell lines, where BPO was more cytotoxic, it readily inactivated PKC due to a slow reversibility of this inactivation by the cell. However, in the JB6 (41 P+) promotable cell line, C3H10T1/2 and B16 melanoma cells, where BPO was less cytotoxic, it did not readily inactivate PKC due to a rapid reversibility of this inactivation by an endogenous mechanism. Nevertheless, BPO inactivated PKC at an equal rate in the homogenates prepared from all these cell types. Inclusion of NADPH reversed this inactivation in the homogenates to a different extent, presumably due to a difference in distribution of a protein disulfide reductase, which reverses this oxidative modification. BPO-induced modification of PKC occurred independent of the cellular status of GSH. However, externally added GSH and cell-impermeable thiol agents prevented the BPO-induced modification of PKC. Since BPO readily partitions into membranes, its reaction with redox-cycling thiols of membrane proteins such as PKC may trigger epigenetic events to prevent cytotoxicity, but favor tumor promotion.
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影响因子：
3.6
作者：
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DOI：
--
发表时间：
1992
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Quest,AF;Bloomenthal,J;Bardes,ES;Bell,RM
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影响因子：
11.2
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DOI：
10.1042/bj2600499
发表时间：
1989
期刊：
The Biochemical journal
影响因子：
--
作者：
Kass,GE;Duddy,SK;Orrenius,S
通讯作者：
Orrenius,S