Villa A, Sironi M, Macchi P, Matteucci C, Notarangelo L D, Vezzoni P, Mantovani A
Istituto di Tecnologie Biomediche Avanzate, Consiglio Nazionale delle Ricerche, Milano, Italy.
Blood. 1996 Aug 1;88(3):817-23.
Janus kinase-3 (Jak3) is a nonreceptor tyrosine kinase functionally coupled to cytokine receptors which share a "common" gamma chain (gamma c). Mutations in gamma c and Jak3 genes have been identified in X-linked and autosomal severe combined immuno deficiency (SCID), respectively. Jak3 is expressed and activated in myelomonocytic cells. The present study was designed to define the structural alteration responsible for lack of Jak3 in a patient with autosomal SCID and to characterize monocyte function in the absence of this signal transduction element, as well as to establish the whole exon-intron structure. Polymerase chain reaction analysis, performed with primers designed on exon sequences, identified 20 exons spanning approximately 15 kb. These primers, or others designed on the flanking sequences provided in the present report, can be used to amplify the whole gene, allowing the definition of the molecular defects in all cases, including prenatal diagnosis, in which transcript analysis is not possible. On this basis, the deletion transcript found at the homozygous state in patient CM, with both his consanguineous parents being heterozygous for the deletion, was associated with mutation (T to C) of a splice donor site of intron 16 that was also detected in his mother's DNA. Monocytes from Jak3-SCID showed normal cytokine production in response to interleukin-4 (IL-4) (release of IL-1 receptor antagonist) and IL-2 (release of tumor necrosis factor-alpha and IL-8). Lipopolysaccharide-induced cytokine production was also normal and was blocked by IL-4 in Jak3- SCID monocytes. Interferon-gamma induced augmented expression of major histocompatibility class II in Jak3-SCID monocytes. These data indicate that Jak3, expressed and activated in myelomonocytic cells, is dispensable for monocyte differentiation and responsiveness to cytokines that interact with gamma c receptors as well as to other regulatory signals.
Janus激酶3（Jak3）是一种非受体酪氨酸激酶，在功能上与共享“共同”γ链（γc）的细胞因子受体偶联。γc和Jak3基因的突变分别在X连锁和常染色体严重联合免疫缺陷（SCID）中被发现。Jak3在骨髓单核细胞中表达并被激活。本研究旨在确定一名常染色体SCID患者中导致Jak3缺失的结构改变，表征在缺乏这种信号转导元件的情况下单核细胞的功能，并确定整个外显子-内含子结构。使用根据外显子序列设计的引物进行聚合酶链反应分析，鉴定出20个外显子，跨度约为15 kb。这些引物或根据本报告提供的侧翼序列设计的其他引物，可用于扩增整个基因，从而在所有情况下（包括无法进行转录本分析的产前诊断）确定分子缺陷。在此基础上，患者CM纯合状态下发现的缺失转录本，其近亲父母均为该缺失的杂合子，与内含子16剪接供体位点的突变（T到C）相关，该突变也在其母亲的DNA中被检测到。来自Jak3-SCID的单核细胞在对白介素-4（IL-4）（IL-1受体拮抗剂的释放）和IL-2（肿瘤坏死因子-α和IL-8的释放）的反应中显示出正常的细胞因子产生。脂多糖诱导的细胞因子产生也正常，并且在Jak3-SCID单核细胞中被IL-4阻断。干扰素-γ诱导Jak3-SCID单核细胞中主要组织相容性复合体II类的表达增加。这些数据表明，在骨髓单核细胞中表达并被激活的Jak3对于单核细胞分化以及对与γc受体相互作用的细胞因子以及其他调节信号的反应性而言并非必需。
