当前位置: X-MOL 学术BBA Gen. Subj. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Radiation activates myeloperoxidase (MPO) to generate active chlorine species (ACS) via a dephosphorylation mechanism - inhibitory effect of LGM2605.
Biochimica et Biophysica Acta (BBA) - General Subjects ( IF 2.8 ) Pub Date : 2020-02-05 , DOI: 10.1016/j.bbagen.2020.129548
Om P Mishra 1 , Anatoliy V Popov 2 , Ralph A Pietrofesa 1 , Wei-Ting Hwang 3 , Mark Andrake 4 , Eiko Nakamaru-Ogiso 5 , Melpo Christofidou-Solomidou 1
Affiliation  

BACKGROUND Radiation exposure of tissues is associated with inflammatory cell influx. Myeloperoxidase (MPO) is an enzyme expressed in granulocytes, such as neutrophils (PMN) and macrophages, responsible for active chlorine species (ACS) generation. The present study aimed to: 1) determine whether exposure to γ-irradiation induces MPO-dependent ACS generation in murine PMN; 2) elucidate the mechanism of radiation-induced ACS generation; and 3) evaluate the effect of the synthetic lignan LGM2605, known for ACS scavenging properties. METHODS MPO-dependent ACS generation was determined by using hypochlorite-specific 3'-(p-aminophenyl) fluorescein (APF) and a highly potent MPO inhibitor, 4-aminobenzoic acid hydrazide (ABAH), and confirmed in PMN derived from MPO-/- mice. Radiation-induced MPO activation was determined by EPR spectroscopy and computational analysis identified tyrosine, serine, and threonine residues near MPO's active site. RESULTS γ-radiation increased MPO-dependent ACS generation dose-dependently in human MPO and in wild-type murine PMN, but not in PMN from MPO-/- mice. LGM2605 decreased radiation-induced, MPO-dependent ACS. Protein tyrosine phosphatase (PTP) and protein serine/threonine phosphatase (PSTP) inhibitors decreased the radiation-induced increase in ACS. Peroxidase cycle results demonstrate that tyrosine phosphorylation blocks MPO Compound I formation by preventing catalysis on H2O2 in the active site of MPO. EPR data demonstrate that γ-radiation increased tyrosyl radical species formation in a dose-dependent manner. CONCLUSIONS We demonstrate that γ-radiation induces MPO-dependent generation of ACS, which is dependent, at least in part, by protein tyrosine and Ser/Thr dephosphorylation and is reduced by LGM2605. This study identified for the first time a novel protein dephosphorylation-dependent mechanism of radiation-induced MPO activation.

中文翻译:


辐射通过去磷酸化机制(LGM2605 的抑制作用)激活髓过氧化物酶 (MPO) 产生活性氯物质 (ACS)。



背景技术组织的辐射暴露与炎症细胞流入相关。髓过氧化物酶 (MPO) 是一种在中性粒细胞 (PMN) 和巨噬细胞等粒细胞中表达的酶,负责活性氯物种 (ACS) 的生成。本研究的目的是: 1) 确定暴露于 γ 辐射是否会诱导小鼠 PMN 中 MPO 依赖性 ACS 的产生; 2)阐明辐射诱发ACS产生的机制; 3) 评估以 ACS 清除特性而闻名的合成木脂素 LGM2605 的效果。方法 通过使用次氯酸盐特异性 3'-(对氨基苯基) 荧光素 (APF) 和高效 MPO 抑制剂 4-氨基苯甲酰肼 (ABAH) 来确定 MPO 依赖性 ACS 的生成,并在源自 MPO-/ 的 PMN 中得到证实。 - 老鼠。通过 EPR 光谱和计算分析确定了辐射诱导的 MPO 活化,确定了 MPO 活性位点附近的酪氨酸、丝氨酸和苏氨酸残基。结果 γ 辐射在人 MPO 和野生型鼠 PMN 中以剂量依赖性方式增加 MPO 依赖性 ACS 的产生,但在 MPO-/- 小鼠的 PMN 中则不然。 LGM2605 降低了辐射诱导的 MPO 依赖性 ACS。蛋白酪氨酸磷酸酶 (PTP) 和蛋白丝氨酸/苏氨酸磷酸酶 (PSTP) 抑制剂可减少辐射诱导的 ACS 增加。过氧化物酶循环结果表明,酪氨酸磷酸化通过阻止 MPO 活性位点中 H2O2 的催化来阻止 MPO 化合物 I 的形成。 EPR 数据表明,γ 辐射以剂量依赖性方式增加酪氨酰自由基的形成。结论 我们证明 γ 辐射诱导 MPO 依赖性 ACS 的产生,这至少部分依赖于蛋白质酪氨酸和 Ser/Thr 去磷酸化,并被 LGM2605 减少。 这项研究首次确定了辐射诱导 MPO 激活的一种新的蛋白质去磷酸化依赖性机制。
更新日期:2020-03-19
down
wechat
bug