Knockout of Raptor destabilizes ornithine decarboxylase mRNA and decreases binding of HuR to the ODC transcript in cells exposed to ultraviolet-B irradiation.
Knockout of Raptor destabilizes ornithine decarboxylase mRNA and decreases binding of HuR to the ODC transcript in cells exposed to ultraviolet-B irradiation.
复制标题
在暴露于紫外线-B 辐射的细胞中，敲除 Raptor 会破坏鸟氨酸脱羧酶 mRNA 的稳定性，并减少 HuR 与 ODC 转录物的结合。
DOI：
10.1016/j.bbrc.2018.10.019
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发表时间：
2018
影响因子：
3.1
通讯作者：
Shantz,LisaM
中科院分区：
文献类型：
--
作者：
Nowotarski,ShannonL;Feehan,RobertP;Presloid,Christopher;Shantz,LisaM
非黑色素瘤皮肤癌 (NMSC) 是美国最常诊断的癌症。紫外线 B (UVB) 照射是刺激 NMSC 发育的主要致癌物。鸟氨酸脱羧酶 (ODC) 是多胺合成中的第一个限速酶，它会因各种增殖刺激（包括 UVB 暴露）而上调。我们之前的研究表明，在致癌 Ras 转化的细胞中，哺乳动物雷帕霉素复合物靶标 1 (mTORC1) 对 ODC 合成的调节。这些研究的目的是更好地了解经 UVB 处理的非转化细胞中 mTORC1 和 ODC 之间的联系。我们发现，通过条件性敲除 mTORC1 的基本成分 Raptor 来消除 mTORC1 活性，导致在暴露于 10mJ/cm2UVB 之前和之后 ODC 蛋白水平下降。此外，在没有 Raptor 的情况下，ODC mRNA 不稳定，表明转录后调控。我们之前已经表明，ODC 转录物通过 RNA 结合蛋白 (RBP) 人类抗原 R (HuR) 进行稳定，并且 HuR 的细胞内定位对 mTORC1 活性的变化做出反应。为了扩展这些研究，我们研究了 HuR 在 UVB 暴露后是否具有调节 ODC mRNA 稳定性的功能。我们的结果显示，与 Raptor 敲除细胞相比，野生型细胞在 UVB 暴露后 HuR 定位于细胞质的增加，并且伴随着 HuR 与 ODC 转录物的更大关联。这些数据表明，HuR 响应 UVB 的定位至少部分受到 mTORC1 的影响，并且 HuR 可以在 UVB 暴露后以 mTORC1 依赖性方式结合并稳定 ODC mRNA。
Non-melanoma skin cancer (NMSC) is the most commonly diagnosed cancer in the United States. Ultraviolet-B (UVB) irradiation is the primary carcinogen responsible for stimulating NMSC development. Ornithine Decarboxylase (ODC), the first rate-limiting enzyme in the synthesis of polyamines, is upregulated in response to a variety of proliferation stimuli, including UVB exposure. Our previous studies have demonstrated regulation of ODC synthesis by the mammalian target of rapamycin complex 1 (mTORC1) in cells transformed by oncogenic Ras. The goal of these studies was to better understand the link between mTORC1 and ODC in nontransformed cells treated with UVB. We show that the ablation of mTORC1 activity by conditional knockout of its essential component Raptor led to decreased levels of ODC protein both before and after exposure to 10 mJ/cm2UVB. Moreover, ODC mRNA was destabilized in the absence of Raptor, suggesting post-transcriptional regulation. We have previously shown that the ODC transcript is stabilized by the RNA binding protein (RBP) human antigen R (HuR), and the intracellular localization of HuR responds to changes in mTORC1 activity. To expand these studies, we investigated whether HuR functions to regulate ODC mRNA stability after UVB exposure. Our results show an increased localization of HuR to the cytoplasm after UVB exposure in wild-type cells compared to Raptor knockout cells, and this is accompanied by greater association of HuR with the ODC transcript. These data suggest that the localization of HuR in response to UVB is influenced, at least in part, by mTORC1 and that HuR can bind to and stabilize ODC mRNA after UVB exposure in an mTORC1-dependent manner.