Qiu Lian-Qun, Abey Sarah, Harris Shawn, Shah Ruchir, Gerrish Kevin E, Blackshear Perry J
Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA.
Environ Health Perspect. 2015 Apr;123(4):324-30. doi: 10.1289/ehp.1408626. Epub 2014 Nov 21.
Inorganic arsenic species are potent environmental toxins and causes of numerous health problems. Most studies have assumed that arsenic-induced changes in mRNA levels result from effects on gene transcription.
We evaluated the prevalence of changes in mRNA stability in response to sodium arsenite in human fibroblasts.
We used microarray analyses to determine changes in steady-state mRNA levels and mRNA decay rates following 24-hr exposure to noncytotoxic concentrations of sodium arsenite, and we confirmed some of these changes using real-time reverse-transcription polymerase chain reaction (RT-PCR).
In arsenite-exposed cells, 186 probe set-identified transcripts were significantly increased and 167 were significantly decreased. When decay rates were analyzed after actinomycin D treatment, only 4,992 (9.1%) of probe set-identified transcripts decayed by > 25% after 4 hr. Of these, 70 were among the 353 whose steady-state levels were altered by arsenite, and of these, only 4 exhibited significantly different decay rates between arsenite and control treatment. Real-time RT-PCR confirmed a major, significant arsenite-induced stabilization of the mRNA encoding δ aminolevulinate synthase 1 (ALAS1), the rate-limiting enzyme in heme biosynthesis. This change presumably accounted for at least part of the 2.7-fold increase in steady-state ALAS1 mRNA levels seen after arsenite treatment. This could reflect decreases in cellular heme caused by the massive induction by arsenite of heme oxygenase mRNA (HMOX1; 68-fold increase), the rate-limiting enzyme in heme catabolism.
We conclude that arsenite modification of mRNA stability is relatively uncommon, but in some instances can result in significant changes in gene expression.
无机砷是强效环境毒素，可引发众多健康问题。多数研究认为，砷诱导的mRNA水平变化源于对基因转录的影响。
我们评估了人成纤维细胞中响应亚砷酸钠时mRNA稳定性变化的发生率。
我们使用微阵列分析来确定在暴露于非细胞毒性浓度的亚砷酸钠24小时后稳态mRNA水平和mRNA降解速率的变化，并使用实时逆转录聚合酶链反应（RT-PCR）确认了其中一些变化。
在暴露于亚砷酸盐的细胞中，186个探针集鉴定的转录本显著增加，167个显著减少。在用放线菌素D处理后分析降解速率时，在4小时后只有4992个（9.1%）探针集鉴定的转录本降解超过25%。其中，70个在353个稳态水平因亚砷酸盐而改变的转录本之中，而在这些转录本中，只有4个在亚砷酸盐和对照处理之间表现出显著不同的降解速率。实时RT-PCR证实，亚砷酸盐可显著诱导编码δ氨基乙酰丙酸合酶1（ALAS1）的mRNA稳定性增加，ALAS1是血红素生物合成中的限速酶。这一变化可能至少部分解释了亚砷酸盐处理后稳态ALAS1 mRNA水平2.7倍的增加。这可能反映了亚砷酸盐大量诱导血红素加氧酶mRNA（HMOX1；增加68倍），即血红素分解代谢中的限速酶，从而导致细胞血红素减少。
我们得出结论，亚砷酸盐对mRNA稳定性的修饰相对不常见，但在某些情况下可导致基因表达的显著变化。
