CPP Tat_(49-57)促进外源CTL表位进入MHC-Ⅰ类抗原呈递途径的机制研究  

Mechanisms of the MHC class I-associated presentation of exogenous CTL epitope fused with cell-penetrating peptides

作　　者：王莉[1] 孟刚[2] 牛微[1] 杨空明 徐文岳[1] 赵婷婷[1] 唐艳[1] 赵建平[1] 吴玉章[1] 

机构地区：[1]第三军医大学基础医学部全军免疫学研究所 [2]第三军医大学西南医院病理学研究所,重庆400038

出　　处：《免疫学杂志》2006年第3期247-251,共5页Immunological Journal

基　　金：国家自然科学基金资助项目(30371329;30400437)

摘　　要：目的研究穿膜肽(cell-penetrating peptides,CPP)促进外源CTL表位进入抗原呈递细胞(antigen-presenting cell,APC)内MHC-Ⅰ类抗原呈递途径的效应及呈递机制。方法应用多肽固相合成技术,将源于HIV-Tat的穿膜序列Tat49-57连接在H-2Kb限制性CTL表位OVA257-264的氨基端形成融合肽即Tat49-57-CTL257-264,同时合成该表位和氨基端自然延伸的对照肽NH2 extended-OVA257-264。采用流式细胞仪(FACS)分析技术,检测APC对各肽的MHC-Ⅰ类抗原呈递动力学,并进行MHC-Ⅰ类抗原呈递阻断和TAP依赖性实验。结果在所测时间点,APC对于Tat49-57-CTL257-264的呈递强度均明显高于NH2 extended-OVA257-264;氨基肽酶抑制剂Bestatin可部分抑制APC对于Tat49-57-CTL257-264的MHC-Ⅰ类抗原呈递,而蛋白酶体抑制剂Lactacystin则无抑制效应;Tat49-57-OVA257-264可被TAP缺陷细胞RMA-S内MHC-Ⅰ类分子有效呈递,其呈递强度远超过RMA-S细胞对NH2extended-OVA257-264的呈递。此外,RMAS固定后则丧失对Tat49-57-OVA257-264和NH2 extended-OVA257-264的MHC-Ⅰ类限制性呈递能力,但其表面的“空”MHC-Ⅰ类分子仍可呈递单纯表位肽OVA257-264。结论CPP Tat49-57可有效促进与之融合的CTL表位肽被细胞内MHC-Ⅰ类分子提呈,表现为动力学显著增强,且该过程表现为蛋白酶体/TAP非依赖、氨基肽酶依赖。Objective To study the time-dependent kinesics and mechanisms of MHC class Ⅰ antigen presentation of CTL epitopes peptides fused with cell-penetrating peptides （CPP）. Methods Peptides termed Tat49-57-OVA257-264, which contains a HIV Tat-derived CPP （Tat49-57） and a H-2K^b-restricted CTL epitope （OVA257-264）, were synthesized with solid-phase synthesis method. An N-termini extended epitope （NH2 extended-OVA257-264） and an epitope peptide （OVA257-264） were used as controls. Flow cytometric analysis was used to detect the time-dependent kinetics of MHC class Ⅰ -associated antigen presentation by APC fed with these peptides. In addition, inhibition and TAP-dependence of MHC class Ⅰ-associated presentation were also explored. Results Tat49-57-OVA257-264 could be more efficiently processed for MHC class Ⅰ molecules presentation than control peptides. Bestatin （a kind of aminopeptidase inhibitor）, not Lactacystin （a kind of proteasome inhibitor）, could partly impair MHC class Ⅰ -associated presentation of Tat49-57-OVA257-264. MHC class Ⅰ -associated presentation of Tat49-57-OVA257-264 was much stronger than that of NH2 extended-OVA257-264 in RMA-S, a TAP-deficient cell. Except the minimal peptide, both two extended peptides failed to be presented by surface class I molecules in fixed cells. Conclusion CPP Tat49-57 can effectively promote the MHC class Ⅰ -associated antigen presentation of CTL epitope, and this course is TAP/proteasome independent as well as aminopeptidase dependent, and need intracellular processing.

关 键 词：穿膜肽 Tat49-57 CTL表位 MHC-Ⅰ类抗原呈递 

分 类 号：R392[医药卫生—免疫学]