β2M Signals Monocytes Through Non-Canonical TGFβ Receptor Signal Transduction.
β2M Signals Monocytes Through Non-Canonical TGFβ Receptor Signal Transduction.
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DOI：
10.1161/circresaha.120.317119
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发表时间：
2021-03-05
影响因子：
20.1
通讯作者：
Morrell CN
中科院分区：
文献类型：
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作者：
Hilt ZT;Maurya P;Tesoro L;Pariser DN;Ture SK;Cleary SJ;Looney MR;McGrath KE;Morrell CN
循环中的单核细胞可以有促炎或修复的表型。体内调节单核细胞极化的内源性信号分子和通路知之甚少。我们发现，血小板衍生的β-2微球蛋白(β-2M)和转化生长因子-β(β)分别通过诱导炎症和修复表型对单核细胞产生相反的作用，但它们都通过相同的受体结合和传递信号。我们现在定义涉及的信号通路。目的：探讨转化生长因子2m和转化生长因子β在体内外调节单核细胞反应的分子机制和信号转导途径。野生型(WT)和血小板特异性β2M基因敲除(PLT-β2M−/−)小鼠静脉注射β2M或转化生长因子β，以提高心血管疾病小鼠的血药浓度。血浆β-2M升高可使促炎性单核细胞增多，而血浆β升高可使促修复单核细胞增多。转化生长因子β受体(βR)在体内抑制单核细胞对β2M和转化生长因子β的钝化反应。流式细胞仪检测发现，β-2M降低单核细胞Smad2/3的核定位，而β促进Smad2/3的核定位，但减少非规范/炎症(JNK和NF-κB的核定位)。这一点在体外得到了成像、流式细胞仪和免疫印迹的证实。β2M，而不是转化生长因子β，促进了Smad3和Smad4的泛素化，从而抑制了它们的核交易。泛素连接酶活性的抑制阻止了非规范的SMAD依赖的单核细胞信号转导，并使单核细胞向有利于修复的单核细胞反应倾斜。我们的结果表明，血浆β-2M和β的升高使单核细胞两极化。此外，这些免疫分子共享一个共同的受体，但以泛素连接酶依赖的方式诱导依赖于sMAD的典型信号(转化生长因子β)和非典型的sMAD不依赖的信号(β2M)。这项工作具有广泛的意义，因为β2M在几种炎症条件下增加，而转化生长因子β在纤维化疾病中增加。单核细胞既可以是促炎的，也可以是修复的，但体内的分子机制还没有很好的描述。我们现在发现，转化生长因子β通过典型的信号转导促进修复前的单核细胞表型，而β2M通过非典型的信号转导途径促进促炎的单核细胞表型。血小板衍生的SMAD2M介导的分子信号通路依赖于β蛋白的泛素化，以防止其移位到细胞核内。这些对信号转导途径的分子控制的新见解可能会导致在疾病状态下调节单核细胞表型的新方法。
Circulating monocytes can have pro-inflammatory or pro-reparative phenotypes. The endogenous signaling molecules and pathways that regulate monocyte polarization in vivo are poorly understood. We have shown that platelet derived beta-2 microglobulin (β2M) and transforming growth factor beta (TGFβ) have opposing effects on monocytes by inducing inflammatory and reparative phenotypes respectively, but each bind and signal through the same receptor. We now define the signaling pathways involved. To determine the molecular mechanisms and signal transduction pathways by which β2M and TGFβ regulate monocyte responses both in vitro and in vivo. Wild-type (WT) and platelet specific β2M knockout (Plt-β2M−/−) mice were treated intravenously with either β2M or TGFβ to increase plasma concentrations to those in cardiovascular diseases. Elevated plasma β2M increased pro-inflammatory monocytes, while increased plasma TGFβ increased pro-reparative monocytes. TGFβ receptor (TGFβR) inhibition blunted monocyte responses to both β2M and TGFβ in vivo. Using imaging flow cytometry, we found that β2M decreased monocyte SMAD2/3 nuclear localization, while TGFβ promoted SMAD nuclear translocation, but decreased non-canonical/inflammatory (JNK and NFκB nuclear localization). This was confirmed in vitro using both imaging flow cytometry and immunoblots. β2M, but not TGFβ, promoted ubiquitination of SMAD3 and SMAD4, that inhibited their nuclear trafficking. Inhibition of ubiquitin ligase activity blocked non-canonical SMAD-independent monocyte signaling and skewed monocytes towards a pro-reparative monocyte response. Our findings indicate that elevated plasma β2M and TGFβ dichotomously polarize monocytes. Furthermore, these immune molecules share a common receptor, but induce SMAD-dependent canonical signaling (TGFβ) versus non-canonical SMAD-independent signaling (β2M) in a ubiquitin ligase dependent manner. This work has broad implications as β2M is increased in several inflammatory conditions, while TGFβ is increased in fibrotic diseases. Monocytes can be polarized as either pro-inflammatory or pro-reparative, but the in vivo molecular mechanisms are not well described. We now show that TGFβ promotes a pro-reparative monocyte phenotype through canonical signal transduction, while β2M promotes a pro-inflammatory monocyte phenotype through a non-canonical signal transduction pathway. Platelet-derived β2M-mediated molecular signaling pathways are dependent on the ubiquitination of SMAD proteins that prevents their translocation into the nucleus. These new insights into the molecular control of the signal transduction pathways may lead to novel means to modulate monocyte phenotype in disease states.