No evidence for immunoproteasomes in chicken lymphoid organs and activated lymphocytes
No evidence for immunoproteasomes in chicken lymphoid organs and activated lymphocytes
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DOI：
10.1007/s00251-014-0814-1
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发表时间：
2015-01-01
期刊：
影响因子：
3.2
通讯作者：
Groettrup, Marcus
中科院分区：
文献类型：
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作者：
Erath, Sonja;Groettrup, Marcus
蛋白酶体是细胞内主要的蛋白质降解机器，为MHC I类分子生产配体。它是一种圆柱形的多催化蛋白酶复合物，催化活性由β 1、β 2和β 5三个亚基介导，它们分别具有半胱天冬酶-、胰蛋白酶-和凝乳胰蛋白酶样活性。通过干扰素(IFN)- γ刺激，诱导β 1i、β 2i和β 5i取代这些亚基，从而形成具有改变的蛋白水解和抗原处理特性的免疫蛋白酶体。编码这些免疫亚基的基因仅限于有颌脊椎动物，但迄今尚未在鸟类基因组中发现，例如鸡、火鸡、鹌鹑、黑松鸡和斑胸草雀。然而，鸡的基因组序列并没有完全确定；因此，我们在蛋白水平上研究了免疫蛋白酶体的存在。从鸡脑、血、脾和法氏囊中纯化20S蛋白酶体，并进行二维凝胶电泳分离。我们用质谱法分析了来自脾脏和大脑的蛋白质斑点，并可以识别所有14个蛋白酶体亚基，但斑点模式没有检测到差异。此外，我们用phorbol 12-肉豆酸13-乙酸酯（PMA）和离子霉素刺激鸡脾脏细胞，目的是诱导免疫蛋白酶体的产生，但尽管诱导了增殖和ifn - γ，但在鸡体内没有发现免疫蛋白酶体形成的证据。从免疫组织和非免疫组织中分离的20S蛋白酶体具有非常相似的肽解活性，这一结果得到了证实。综上所述，我们的结果表明鸡在蛋白质水平上也缺乏免疫蛋白酶体。
The proteasome is the main protein-degrading machine within the cell, producing ligands for MHC class I molecules. It is a cylindrical multicatalytic protease complex, and the catalytic activity is mediated by the three subunits beta 1, beta 2, and beta 5 which possess caspase-, trypsin-, and chymotrypsin-like activities, respectively. By stimulation with interferon (IFN)-gamma the replacement of these subunits by beta 1i, beta 2i, and beta 5i is induced leading to formation of immunoproteasomes with altered proteolytic and antigen processing properties. The genes coding for these immunosubunits are restricted to jawed vertebrates but have so far not been found in the genomes of birds, e.g., chicken, turkey, quail, black grouse and zebra finch. However, the chicken genome sequences are not completely assigned; therefore, we investigated the presence of immunoproteasome on protein level. 20S proteasome was purified from the chicken brain, blood, spleen, and bursa of Fabricius, followed by separation via two-dimensional (2D) gel electrophoresis. We analyzed the protein spots derived from the spleen and brain by mass spectrometry and could identify all 14 proteasomal subunits, but there were no differences detectable in the spot patterns. Moreover, we stimulated the chicken spleen cells with phorbol 12-myristate 13-acetate (PMA) and ionomycin aiming at the induction of immunoproteasome, but in spite of the induction of proliferation and IFN-gamma, no evidence for immunoproteasome formation in chicken could be obtained. This result was substantiated by the finding that 20S proteasomes isolated from immune and non-immune tissues showed very similar peptidolytic activities. Taken together, our results indicate that chicken lack immunoproteasomes also on protein level.