A Heterozygous RAB27A Mutation Associated with Delayed Cytolytic Granule Polarization and Hemophagocytic Lymphohistiocytosis.
A Heterozygous RAB27A Mutation Associated with Delayed Cytolytic Granule Polarization and Hemophagocytic Lymphohistiocytosis.
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DOI：
10.4049/jimmunol.1501284
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发表时间：
2016-03-15
期刊：
影响因子：
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通讯作者：
Cron RQ
中科院分区：
文献类型：
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作者：
Zhang M;Bracaglia C;Prencipe G;Bemrich-Stolz CJ;Beukelman T;Dimmitt RA;Chatham WW;Zhang K;Li H;Walter MR;De Benedetti F;Grom AA;Cron RQ
由于自然杀伤细胞(NK)和CD8 T细胞溶解途径基因的纯合子突变，婴儿时期经常发生致命的原发噬血细胞淋巴组织细胞增多症(HLH)。继发性高促黄体生成素出现在婴儿时期，可能与高促黄体激素基因杂合突变有关。我们报告2例无血缘关系的青少年HLH和一个相同的杂合子RAB27A突变(C.259G>；C)。我们在将此Rab27A错义突变(p.A87P)导入人NK-92细胞系之前，通过将其克隆到慢病毒表达载体中来探讨其对NK细胞杀伤功能的贡献。比较突变型和野生型转导的NK-92细胞的NK细胞脱颗粒(CD107a表达)、靶细胞结合和K562靶细胞裂解。用共聚焦显微镜观察颗粒酶B对免疫突触的极化以及突变体Rab27A(p.A87P)与Munc13-4的相互作用。RAB27A突变过表达对NK细胞与靶细胞之间的结合没有影响，但降低了NK细胞的杀伤活性和脱颗粒。此外，突变的Rab27A蛋白减少了与Munc13-4的结合，并延迟了颗粒酶B对免疫突触的极化。这种RAB27A杂合子突变通过部分显性-负效应导致HLH，从而模糊了原发和继发HLH之间的遗传差异。
Frequently fatal, primary hemophagocytic lymphohistiocytosis (HLH) occurs in infancy resulting from homozygous mutations in natural killer (NK) and CD8 T cell cytolytic pathway genes. Secondary HLH presents after infancy and may be associated with heterozygous mutations in HLH genes. We report 2 unrelated teenagers with HLH and an identical heterozygous RAB27A mutation (c.259G>C). We explore the contribution of this Rab27A missense (p.A87P) mutation on NK cell cytolytic function by cloning it into a lentiviral expression vector prior to introduction into the human NK-92 cell line. NK cell degranulation (CD107a expression), target cell conjugation, and K562 target cell lysis was compared between mutant and wild-type transduced NK-92 cells. Polarization of granzyme B to the immunologic synapse and interaction of mutant Rab27A (p.A87P) with Munc13-4 were explored by confocal microscopy and proximity ligation assay, respectively. Over-expression of the RAB27A mutation had no effect on cell conjugate formation between the NK and target cells but decreased NK cell cytolytic activity and degranulation. Moreover, the mutant Rab27A protein decreased binding to Munc13-4 and delayed granzyme B polarization towards the immunologic synapse. This heterozygous RAB27A mutation blurs the genetic distinction between primary and secondary HLH by contributing to HLH via a partial dominant-negative effect.