
DNA分子模型(圖)
在過去幾年中,許多研究報道顯示長期壓力會引起染色體損傷,但具體仍然機制不明。美國杜克大學醫(yī)學院的科學家們最新的研究發(fā)現(xiàn)了壓力導致DNA損傷的分子機制。
這項研究的論文發(fā)表在了最新一期的《Nature》雜志上。
論文的通訊作者,Robert J. Lefkowitz教授說道:“我們證實了長期壓力會通過一種特定的機制上調(diào)人體內(nèi)的腎上腺素,并最終導致DNA受損。”
在研究中,小鼠被注射入一種腎上腺素類似化合物,它可通過一種名為β-腎上腺素能受體發(fā)揮作用(Lefkowitz研究該受體已有數(shù)年)。科學家們發(fā)現(xiàn)在這種使用藥物建立的慢性壓力小鼠模型中,體內(nèi)會啟動特定的一些生物學通路,誘導DNA的損傷并積累。
Lefkowitz教授說道:“這可以解釋為何長期的壓力會導致人體內(nèi)環(huán)境的一系列改變和失調(diào)!
P53是人體內(nèi)的抑癌基因,被認為是基因組的“守護者”,它能阻止基因組發(fā)生異常。
Lefkowitz的實驗室的一位博士后Makoto Hara說道:“研究顯示長期的壓力會導致體內(nèi)P53表達水平一直較低,我們推測這是染色體變得無規(guī)律的根本原因!
β-腎上腺素能受體是一種G蛋白偶聯(lián)受體(GPCRs),這些受體通常表達于細胞的表面,是目前市面上一半以上藥物的作用靶點。
該研究小組一直在研究起源于GPCRs的一條名為β-阻滯的信號通路。起初,他們推斷β-阻滯蛋白能通過關(guān)閉或降低敏感性對G蛋白通路進行抑制,但證據(jù)顯示這些蛋白的積累也會最終引發(fā)一些它們自身的生物活力。
在該研究中,腎上腺素類似化合物通過G蛋白通路和β-阻滯通路共同作用影響P53的正常表達,誘導DNA損傷。小鼠在注射該化合物的四周后,體內(nèi)P53表達水平顯著降低。同時科學家們還發(fā)現(xiàn),在缺乏β-阻滯蛋白1的情況下,小鼠DNA不會受損。因為β-阻滯蛋白1表達缺失可有效穩(wěn)定胸腺細胞內(nèi)的P53表達水平(胸腺和急性、慢性壓力反應相關(guān))。(生物探索 Jun譯)
生物探索推進英文論文原文摘要:
A stress response pathway regulates DNA damage through β2-adrenoreceptors and β-arrestin-1
The human mind and body respond to stress1, a state of perceived threat to homeostasis, by activating the sympathetic nervous system and secreting the catecholamines adrenaline and noradrenaline in the ‘fight-or-flight’ response. The stress response is generally transient because its accompanying effects (for example, immunosuppression, growth inhibition and enhanced catabolism) can be harmful in the long term. When chronic, the stress response can be associated with disease symptoms such as peptic ulcers or cardiovascular disorders, and epidemiological studies strongly indicate that chronic stress leads to DNA damage. This stress-induced DNA damage may promote ageing, tumorigenesis, neuropsychiatric conditions and miscarriages. However, the mechanisms by which these DNA-damage events occur in response to stress are unknown. The stress hormone adrenaline stimulates β2-adrenoreceptors that are expressed throughout the body, including in germline cells and zygotic embryos. Activated β2-adrenoreceptors promote Gs-protein-dependent activation of protein kinase A (PKA), followed by the recruitment of β-arrestins, which desensitize G-protein signalling and function as signal transducers in their own right. Here we elucidate a molecular mechanism by which β-adrenergic catecholamines, acting through both Gs–PKA and β-arrestin-mediated signalling pathways, trigger DNA damage and suppress p53 levels respectively, thus synergistically leading to the accumulation of DNA damage. In mice and in human cell lines, β-arrestin-1 (ARRB1), activated via β2-adrenoreceptors, facilitates AKT-mediated activation of MDM2 and also promotes MDM2 binding to, and degradation of, p53, by acting as a molecular scaffold. Catecholamine-induced DNA damage is abrogated in Arrb1-knockout (Arrb1−/− mice, which show preserved p53 levels in both the thymus, an organ that responds prominently to acute or chronic stress1, and in the testes, in which paternal stress may affect the offspring’s genome. Our results highlight the emerging role of ARRB1 as an E3-ligase adaptor in the nucleus, and reveal how DNA damage may accumulate in response to chronic stress. |