Ubiquitin-like polypeptide conjugates to acceptor proteins in concanavalin A- and interferon γ-stimulated T-cells
Ubiquitin-like polypeptide conjugates to acceptor proteins in concanavalin A- and interferon γ-stimulated T-cells
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DOI：
10.1042/bj3300683
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发表时间：
1998-03-01
影响因子：
4.1
通讯作者：
Tanigawa, Y
中科院分区：
文献类型：
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作者：
Nakamura, M;Tanigawa, Y
单克隆性非特异性抑制因子(MNSF)是由小鼠T细胞杂交瘤产生的一种淋巴因子，具有多营养非特异性抑制功能。MNSFβ是MNSF的一个亚基，是一个14.5 kDa的融合蛋白，由一个与泛素和核糖体蛋白S30有36%同源性的蛋白组成。MNSFβ泛素样段(Ubi-L)是一个8 kDa的多肽，具有MNSF样活性。由于泛素化过程中关键的氨基酸在Ubi-L中是保守的，我们研究了Ubi-L是否以类似于泛素系统的方式与细胞内蛋白质结合。抗Ubi-L的兔多克隆抗体能诱导刀豆蛋白A(ConA)刺激的T细胞结合Ubi-L，但不能诱导脂多糖刺激的B细胞和巨噬细胞结合Ubi-L。在PAN-T细胞中始终存在大分子质量的偶联物。然而，并不是所有受试细胞都能观察到游离Ubi-L。ConA激活的CD8(+)T细胞，而不是CD4(+)T细胞，诱导了70 kDa的Ubi-L加合物，该加合物可被抗单核细胞生长因子的单抗识别。用干扰素-γ处理CD8(+)T细胞也能引起70 kDa Ubi-L加合物的表达，而对干扰素α和干扰素β的反应为零。经抗原和刀豆蛋白A刺激的小鼠辅助性T细胞克隆D.10 G4.1可诱导33.5 kDa的加合物，但不能诱导70 kDa的加合物。这些结果提示乌比-L结合在调节T细胞活化中起作用。
Monoclonal non-specific suppressor factor (MNSF), a lymphokine produced by a murine T-cell hybridoma, possesses pleiotrophic non-specific suppressive functions. MNSF beta (a subunit of MNSF) is a 14.5 kDa fusion protein consisting of a protein with 36% homology with ubiquitin and ribosomal protein S30. The ubiquitin-like segment of MNSF beta (Ubi-L) is an 8 kDa polypeptide with MNSF-like activity. Since the amino acids critical for the ubiquitination process are conserved in Ubi-L, we examined whether Ubi-L may conjugate with intracellular proteins in a manner similar to the ubiquitin system. Rabbit polyclonal antibodies specific for Ubi-L detected the induction of Ubi-L conjugations, including 33.5 kDa and 70 kDa molecules in concanavalin A (Con A)-stimulated T-cells, but not in lipopolysaccharide-stimulated B-cells and macrophages. High-molecular-mass conjugates were consistently present in pan-T-cells. However, free Ubi-L could not be observed in all the cells tested. Con A-activated CD8(+) T-cells, but not CD4(+) T-cells, induced the 70 kDa Ubi-L adduct, which was recognized by an anti-MNSF monoclonal antibody. Treatment of CD8(+) T-cells with interferon (IFN) gamma also caused the expression of the 70 kDa Ubi-L adduct, whereas the responses to IFN alpha and IFN beta were nil. Antigen-and Con A-stimulated D.10 G4.1, a murine T helper clone type 2, induced the 33.5 kDa, but not the 70 kDa, adduct. These results suggest a role for Ubi-L conjugation in the regulation of T-cell activation.