Knocking down raptor in human keratinocytes affects ornithine decarboxylase in a post-transcriptional Manner following ultraviolet B exposure.
Knocking down raptor in human keratinocytes affects ornithine decarboxylase in a post-transcriptional Manner following ultraviolet B exposure.
复制标题
在紫外线 B 暴露后，敲低人类角质形成细胞中的 raptor 以转录后方式影响鸟氨酸脱羧酶。
DOI：
10.1007/s00726-019-02732-3
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发表时间：
2020
期刊：
影响因子：
3.5
通讯作者：
Nowotarski,ShannonL
中科院分区：
文献类型：
--
作者：
Stump,CorynL;Feehan,RobertP;Jordan,Torey;Shantz,LisaM;Nowotarski,ShannonL
非黑色素瘤皮肤癌(NMSC)是最常见的癌症。紫外线-B(UVB)辐射在NMSC的发展过程中是一种完全的致癌物。雷帕霉素复合体1(MTORC1)的哺乳动物靶点被UVB上调。鸟氨酸脱羧酶(ODC)是多胺生物合成途径中的第一个酶，也是对UVB的响应上调。然而，UVB暴露后这两条通路之间的相互作用仍不清楚。本研究比较了正常人角质形成细胞(HaCaT细胞)和低水平Raptor的HaCaT细胞的mRNA稳定性，以探讨UVB诱导ODC是否依赖mTORC1。我们发现，mTORC1活性的下调导致了20 mJ/cm2UVB照射前后ODC蛋白水平的下降。在mTORC1活性降低的细胞中，ODC mRNA的稳定性较差。多聚体图谱显示，经UVB处理的细胞中，ODC mRNA翻译的起始没有改变。我们已经证明ODC转录本是由RNA结合蛋白人类抗原R(HUR)稳定的。为了扩展这些研究，我们调查了HUR是否在UVB暴露的人角质形成细胞中调节ODC mRNA的稳定性。我们发现在UVB照射后，野生型细胞中HUR的胞质定位增加。通过CRISPR/Cas9消融HUR并没有改变ODC信息的稳定性，这表明其他反式作用因子参与其中。这些数据表明，在人角质形成细胞中，ODC mRNA的稳定性在一定程度上受到UVB照射后mTORC1依赖的机制的调节。
Non-melanoma skin cancer (NMSC) is the most common form of cancer. Ultraviolet-B (UVB) radiation has been shown to be a complete carcinogen in the development of NMSC. The mammalian target of rapamycin complex 1 (mTORC1) is upregulated by UVB. Ornithine decarboxylase (ODC), the first enzyme of the polyamine biosynthetic pathway, is also upregulated in response to UVB. However, the interplay between these two pathways after UVB exposure remains unclear. The studies described here compare mRNA stability between normal human keratinocytes (HaCaT cells) and HaCaT cells with low levels of raptor to investigate whether the induction of ODC by UVB is dependent on mTORC1. We show that the knockdown of mTORC1 activity led to decreased levels of ODC protein both before and after exposure to 20 mJ/cm2UVB. ODC mRNA was less stable in cells with decreased mTORC1 activity. Polysome profiles revealed that the initiation of ODC mRNA translation did not change in UVB-treated cells. We have shown that the ODC transcript is stabilized by the RNA-binding protein human antigen R (HuR). To expand these studies, we investigated whether HuR functions to regulate ODC mRNA stability in human keratinocytes exposed to UVB. We show an increased cytoplasmic localization of HuR after UVB exposure in wild-type cells. The ablation of HuR via CRISPR/Cas9 did not alter the stability of the ODC message, suggesting the involvement of other trans-acting factors. These data suggest that in human keratinocytes, ODC mRNA stability is regulated, in part, by an mTORC1-dependent mechanism after UVB exposure.