The Inflammatory Bowel Disease-Associated Autophagy Gene Atg16L1T300A Acts as a Dominant Negative Variant in Mice
The Inflammatory Bowel Disease-Associated Autophagy Gene Atg16L1T300A Acts as a Dominant Negative Variant in Mice
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炎症性肠病 - 相关自噬基因 Atg16L1T300A 在小鼠中充当显性阴性变异
DOI：
10.4049/jimmunol.1502652
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发表时间：
2017-03-15
影响因子：
4.4
通讯作者：
Zhang, Fuping
中科院分区：
文献类型：
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作者：
Gao, Ping;Liu, Hongtao;Zhang, Fuping
Atg16L1T300A多态性导致克罗恩病风险增加的原因尚不完全清楚。最近的一项重要研究表明，Atg16L1T300A的小鼠等效物（Atg16L1T316A）对caspase 3介导的裂解表现出更高的敏感性，并导致巨噬细胞中全长Atg16L1的水平下降。然而，尽管这一发现表明这种多态性是一种功能缺失的异常，但它并没有解决这种多态性也影响杂合小鼠正常Atg16L1等位基因功能的可能性。因此，我们评估了Atg16L1T300A多态性杂合子和纯合子在敲入（KI）小鼠中的功能。令人惊讶的是，我们发现两种KI小鼠的巨噬细胞都表现出缺陷的自噬诱导；因此，两种类型的小鼠都表现出细菌清除缺陷，同时炎症小体细胞因子（IL-1 β）反应增加。此外，来自两种KI小鼠的巨噬细胞在tnf α诱导的Atg16L1T300A切割中表现出缺陷，细菌滞留增加，细菌传播增加，沙门氏菌诱导的结肠炎。这些研究表明，携带Atg16L1T300A多态性的染色体可以干扰野生型（WT） Atg16L1等位基因的功能，因此，克罗恩病风险多态性是一种显性阴性变异，即使只存在于一条染色体上，也有可能作为一种疾病因素。携带WT Atg16L1等位基因和空等位基因的小鼠（Atg16L1（KO/+）小鼠）表现出与WT小鼠相当的正常自噬功能，这一发现支持了这一结论。
The basis of the increased risk for Crohn's disease conferred by the Atg16L1T300A polymorphism is incompletely understood. An important step forward came from the recent demonstration that the murine equivalent of Atg16L1T300A (Atg16L1T316A) exhibits increased susceptibility to caspase 3-mediated cleavage and resulting decreased levels of full-length Atg16L1 in macrophages. However, although this finding showed that this polymorphism is a loss-of-function abnormality, it did not address the possibility that this polymorphism also affects the function of a normal Atg16L1 allele in heterozygous mice. Therefore, we evaluated the function of the Atg16L1T300A polymorphism heterozygote and homozygote in knock-in (KI) mice. Surprisingly, we found that macrophages from both types of KI mice exhibit defective autophagic induction; accordingly, both types of mice exhibit defects in bacterial clearance coupled with increased inflammasome cytokine (IL-1 beta) responses. Furthermore, macrophages from both types of KI mice displayed defects in TNF-alpha-induced Atg16L1T300A cleavage, increased retention of bacteria, bacterial dissemination, and Salmonella-induced colitis. These studies suggested that chromosomes bearing the Atg16L1T300A polymorphism can interfere with the function of the wild-type (WT) Atg16L1 allele and, thus, that the Crohn's disease risk polymorphism is a dominant-negative variant with the potential to act as a disease factor, even when present on only one chromosome. This conclusion was supported by the finding that mice bearing a WT Atg16L1 allele and a null allele (Atg16L1(KO/+) mice) exhibit normal autophagic function equivalent to that of WT mice.