短期模拟失重可引起大鼠视交叉上核中枢时钟基因的表达异常
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摘要
目的探讨1周模拟失重对大鼠生物钟中枢时钟基因表达影响。方法采用尾悬吊后肢去负荷模型模拟太空微重力环境,48只雄性SD大鼠随机均分为对照(control,CON)组和尾悬吊(tail-suspension,SUS)组。两组大鼠在相同的光照环境下(08:00～20:00)饲养。蛋白印迹实验检测大鼠视交叉上核(suprachiasmatic nucleus,SCN)内时钟基因(Per2,Bmal1)以及钙通道Cav1.2蛋白在不同时间点的表达水平,同时采用实时定量PCR技术检测不同时间点SCN中Per2,Bmal1的转录水平。结果与CON组相比,短期模拟失重引起大鼠SCN中时钟基因Per2和Bmal1 mRNA转录和蛋白表达下降(P<0. 05),且波动幅度发生显著降低。此外,与对照组相比,模拟失重使得SUS组大鼠SCN中Cav1.2蛋白表达发生了明显上升(P<0.05)。结论短期模拟失重可引起大鼠时钟基因表达异常,这可能是模拟失重引起机体发生病理性改变的机制之一,也为重力变化信号直接转化为时间节律信号提供了直接的证据。
AIM To evaluate the effects of one-week simulated microgravity on the expression of circadian rhythm in rats. METHODS The tail suspension hindlimb unloading model was used to simulate a space microgravity environment. 48 male SD rats(aged 8 weeks) were randomly assigned to a control(CON) and a tail suspension(SUS) group(24 each). Rats in both groups were housed under the same light conditions(8:00-20:00). Western blotting was used to detect the expression levels of clock genes(Per2, Bmal1) and ion channels Cav1.2 protein in the suprachiasmatic nucleus(SCN) of rats at different time points. Real-time quantitative PCR was used to detect the transcription levels of Per2 and Bmal1 in SCN at different time points. RESULTS Short-term simulated weightlessness caused a decrease in the transcription and protein expression of clock genes Per2 and Bmal1 in rat SCN(P<0.05) and the fluctuation amplitude was significantly reduced. In addition, compared with that in the control group, simulated weightlessness caused a significant increase in Cav1.2 protein expression in SCN of SUS rats. CONCLUSION Short-term simulated weightlessness can cause abnormal expression of rat clock genes, which may be one of the mechanisms that simulate pathological changes of the body caused by weightlessness. This finding provides direct evidence for the direct conversion of gravity-changing signals into time-ratio signals.
AIM To evaluate the effects of one-week simulated microgravity on the expression of circadian rhythm in rats. METHODS The tail suspension hindlimb unloading model was used to simulate a space microgravity environment. 48 male SD rats(aged 8 weeks) were randomly assigned to a control(CON) and a tail suspension(SUS) group(24 each). Rats in both groups were housed under the same light conditions(8:00-20:00). Western blotting was used to detect the expression levels of clock genes(Per2, Bmal1) and ion channels Cav1.2 protein in the suprachiasmatic nucleus(SCN) of rats at different time points. Real-time quantitative PCR was used to detect the transcription levels of Per2 and Bmal1 in SCN at different time points. RESULTS Short-term simulated weightlessness caused a decrease in the transcription and protein expression of clock genes Per2 and Bmal1 in rat SCN(P<0.05) and the fluctuation amplitude was significantly reduced. In addition, compared with that in the control group, simulated weightlessness caused a significant increase in Cav1.2 protein expression in SCN of SUS rats. CONCLUSION Short-term simulated weightlessness can cause abnormal expression of rat clock genes, which may be one of the mechanisms that simulate pathological changes of the body caused by weightlessness. This finding provides direct evidence for the direct conversion of gravity-changing signals into time-ratio signals.
引文
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[3] Karemaker JM ,Berecki-Gisolf J.24-h blood pressure in Space:The dark side of being an astronaut[J].Respir Physiol Neurobiol,2009,169(Suppl 1),S55-S58.
[4] Morey-Holton ER,Globus RK.Hindlimb unloading rodent model:technical aspects[J].J Appl Physiol (1985),2002,92(4):1367-1377.
[5] Colwell CS.Linking neural activity and molecular oscillations in the SCN[J].Nature Reviews Neuroscience,2011,12(10):553-569.
[6] Schmutz I,Chavan R,Ripperger JA,et al.A specific role for the REV-ERBα-controlled L-Type Voltage-Gated Calcium Channel CaV1.2 in resetting the circadian clock in the late night[J].J Biol Rhythms,2014,29(4):288-298.
[7] Dibner C,Schibler U,Albrecht U.The mammalian circadian timing system:organization and coordination of central and peripheral clocks[J].Annu Rev Physiol,2010,72:517-549.
[8] Stephan FK.The “Other” Circadian System:Food as a Zeitgeber[J].J Biol Rhythms,2002,17(4):284-292.
[9] Frigeri A,Iacobas DA,Iacobas S,et al.Effect of microgravity on gene expression in mouse brain[J].Exp Brain Res,2008,191(3):289-300.
[10]Fuller CA,Hobanhiggins TM,Griffin DW,et al.Influence of gravity on the circadian timing system[J].Adv Space Res,1994,14(8):399-408.
[11]Biao Y ,Tianyuan HU.Study and analysis of microgravity environment onboard manned space station[J].Manned Spaceflight,2014(2):178-183.
[12]Legan SJ,Peng X,Yun C,et al.Effect of arousing stimuli on circulating corticosterone and the circadian rhythms of luteinizing hormone (LH) surges and locomotor activity in estradiol-treated ovariectomized (ovx+EB) Syrian hamsters[J].Horm Behav,2015,72:28-38.
[13]Yang S,Liu Y,Yang Y,et al.Simulated microgravity influences circadian rhythm of NIH3T3 cells[J].J Interdiscipl Cycle Res,2016,47(6):897-907.
[14]Partch CL,Green CB,Takahashi JS.Molecular architecture of the mammalian circadian clock[J].Trends Cell Biol,2014,24(2):90-99.
[15]Koike N,Yoo SH,Huang HC,et al.Transcriptional Architecture and Chromatin Landscape of the Core Circadian Clock in Mammals[J].Science,2012,338(6105):349-354.
[16]Rey G,Cesbron F,Rougemont J,et al.Genome-wide and phase-specific DNA-binding rhythms of BMAL1 control circadian output functions in mouse liver[J].PLoS Biology,2011,9(2):e1000595.
[17]Lee C,Etchegaray JP,Cagampang FRA,et al.Posttranslational mechanisms regulate the mammalian circadian clock[J].Cell,2001,107(7):855-867.
[18]Dunlap JC .Molecular bases for circadian clocks[J].Cell,1999,96(2):271-290.
[19]Kondratov RV,Kondratova AA,Gorbacheva VY,et al.Early aging and age-related pathologies in mice deficient in BMAL1,the core componentof the circadian clock[J].Genes Dev,2006,20(14):1868-1873.
[20]Mcdearmon EL,Patel KN,Ko CH,et al.Dissecting the functions of the mammalian clock protein BMAL1 by tissue-specific rescue in mice[J].Science,2006,314(5803):1304-1308.
[21]Miyazaki K,Wakabayashi M,Chikahisa S,et al.PER2 controls circadian periods through nuclear localization in the suprachiasmatic nucleus[J].Genes Cells,2007,12(11):1225-1234.
[22]Chen R,Schirmer A,Lee Y,et al.Rhythmic PER abundance defines a critical nodal point for negative feedback within the circadian clock mechanism[J].Molecular Cell,2009,36(3):417-430.
[23]Zheng B,Larkin DW,Albrecht U,et al.The mPer2 gene encodes a functional component of the mammalian circadian clock[J].Nature,1999,400(6740):169-173.