HSC70 blockade by the therapeutic peptide P140 affects autophagic processes and endogenous MHCII presentation in murine lupus
HSC70 blockade by the therapeutic peptide P140 affects autophagic processes and endogenous MHCII presentation in murine lupus
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DOI：
10.1136/ard.2010.139832
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发表时间：
2011-05-01
影响因子：
27.4
通讯作者：
Muller, Sylviane
中科院分区：
文献类型：
--
作者：
Page, Nicolas;Gros, Frederic;Muller, Sylviane
P140磷酸肽来源于剪接体U1- 70 K小核核糖核蛋白，在MRL/lpr狼疮易感小鼠中显示出保护特性。它结合主要组织相容性II类（MHCII）和HSC 70/Hsp 73分子。目的探讨P140肽对HSC 70+抗原提呈细胞的作用机制。方法应用图像分析系统、荧光显微镜和电子显微镜对P140在HSC 70+抗原提呈细胞中的分布进行真实的实时监测。采用荧光激活细胞分选和Western blotting方法检测P140对自噬通量的影响。在正常小鼠中，P140肽减少外周和脾T和B细胞的数量，而不影响这些细胞。剩余的MRL/lpr B细胞对有丝分裂原反应正常。P140肽降低了MRL/lpr脾B细胞中HSC 70/Hsp 73分子伴侣和稳定的MHCII二聚体的表达水平。它损害了分子伴侣HSC 70的重折叠特性。在MRL/lpr B细胞中，自噬标志物p62/SQSTM 1和LC 3-II的积累增加，与自噬流过程中溶酶体降解的下调一致。结论P140肽与HSC 70结合后，MRL/lpr抗原提呈B细胞的内源性（自身）抗原加工可能受到很大影响。导致观察到的自身反应性T细胞引发和通过涉及溶酶体降解途径的机制的信号传导的减少。这种意想不到的机制可能解释了P140肽在治疗的MRL/lpr小鼠中的有益作用。
Background The P140 phosphopeptide issued from the spliceosomal U1-70K small nuclear ribonucleoprotein protein displays protective properties in MRL/lpr lupus-prone mice. It binds both major histocompatibility class II (MHCII) and HSC70/Hsp73 molecules. P140 peptide increases MRL/lpr peripheral blood lymphocyte apoptosis and decreases autoepitope recognition by T cells.Objective To explore further the mode of action of P140 peptide on HSC70+ antigen-presenting cells.Methods P140 biodistribution was monitored in real time using an imaging system and by fluorescence and electron microscopy. Fluorescence activated cell sorting and Western blotting experiments were used to evaluate the P140 effects on autophagic flux markers.Results P140 fluorescence accumulated especially in the lungs and spleen. P140 peptide reduced the number of peripheral and splenic T and B cells without affecting these cells in normal mice. Remaining MRL/lpr B cells responded normally to mitogens. P140 peptide decreased the expression levels of HSC70/Hsp73 chaperone and stable MHCII dimers, which are both increased in MRL/lpr splenic B cells. It impaired refolding properties of chaperone HSC70. In MRL/lpr B cells, it increased the accumulation of the autophagy markers p62/SQSTM1 and LC3-II, consistent with a downregulated lysosomal degradation during autophagic flux.Conclusion The study results suggest that after P140 peptide binding to HSC70, the endogenous (auto) antigen processing might be greatly affected in MRL/lpr antigen-presenting B cells, leading to the observed decrease of autoreactive T-cell priming and signalling via a mechanism involving a lysosomal degradation pathway. This unexpected mechanism might explain the beneficial effect of P140 peptide in treated MRL/lpr mice.