目的:探究清除Vγ4T细胞在小鼠皮肤紫外线损伤后表皮组织修复中的作用及其机制。方法:该研究为实验研究。将54只6~8周龄雌性C57BL/6J野生型小鼠按照随机数字表法分为Vγ4T细胞清除组和对照组（每组27只），分别腹腔注射亚美尼亚仓鼠抗小鼠Vγ4T细胞受体（TCR）单克隆抗体200 μg、等量同型对照IgG抗体。注射后1周（之后均在此时间点取小鼠），每组取3只小鼠（之后均从这2组另取小鼠），从背部皮肤组织和腋窝、腹股沟淋巴结中分别提取真皮细胞和淋巴结细胞，行流式细胞术检测真皮细胞和淋巴结细胞中Vγ4T细胞比例；每组取5只小鼠，观察背部皮肤情况，之后行苏木精-伊红（HE）染色观察皮肤组织结构并测量表皮组织厚度；每组取5只小鼠，提取表皮细胞后行流式细胞术检测表皮细胞中树突状表皮T细胞（DETC）比例。每组取3只小鼠，分别设为Vγ4T细胞清除+5次紫外线辐射（UVR）组和对照+5次UVR组，每日1次共行5次UVR，每日照射后即刻观察背部皮肤情况；每组取5只小鼠，分别设为Vγ4T细胞清除+1次UVR组和对照+1次UVR组，均行1次UVR后即刻行HE染色后测量表皮组织厚度。每组取3只小鼠，分别设为单纯Vγ4T细胞清除组、单纯对照组；再另取3只小鼠，分别设为Vγ4T细胞清除+1次UVR组和对照+1次UVR组；均同前处理后，采用实时荧光定量反转录PCR法检测表皮组织中胰岛素样生长因子Ⅰ（IGF-Ⅰ）、角质形成细胞生长因子（KGF）、Vγ5TCR、白细胞介素15（IL-15）、IL-1β、IL-23、自然杀伤细胞2族成员D（NKG2D）、组织相容性抗原60（H60）、小鼠UL16结合蛋白样转录子1（Mult1）、维甲酸早期诱导蛋白1（Rae1）的mRNA表达。结果:注射后1周，Vγ4T细胞清除组小鼠真皮细胞、淋巴结细胞中Vγ4T细胞比例均明显低于对照组（ t值分别为27.99、13.12， P<0.05）；Vγ4T细胞清除组和对照组小鼠皮肤大体情况和组织结构无明显区别，表皮组织厚度相近（ P>0.05）；Vγ4T细胞清除组小鼠表皮细胞中DETC比例为（3.9±0.8）%，明显高于对照组的（1.6±0.5）%（ t=4.84， P<0.05）。与对照+5次UVR组相比，Vγ4T细胞清除+5次UVR组小鼠进行1次UVR后皮肤鳞屑增多，照射2次出现鳞屑样痂皮，照射3~5次鳞屑样痂皮明显增多。行UVR后即刻，Vγ4T细胞清除+1次UVR组小鼠表皮组织厚度较对照+1次UVR组明显增加（ t=11.50， P<0.05）。与单纯对照组相比，单纯Vγ4T细胞清除组小鼠表皮组织中Vγ5TCR的mRNA表达明显上调（ t=41.16， P<0.05），IL-23的mRNA表达明显下调（ t=6.52， P<0.05）；与单纯对照组相比，对照+1次UVR组小鼠表皮组织中Vγ5TCR、KGF的mRNA表达均明显上调（ t值分别为15.22、13.22， P<0.05），IGF-Ⅰ、IL-23的mRNA表达均明显下调（ t值分别为3.71、4.95， P<0.05）；与单纯Vγ4T细胞清除组相比，Vγ4T细胞清除+1次UVR组小鼠表皮组织中IGF-Ⅰ、KGF的mRNA表达均明显上调（ t值分别为11.40、18.88， P<0.05），IL-1β的mRNA表达明显下调（ t=4.42， P<0.05）；与对照+1次UVR组相比，Vγ4T细胞清除+1次UVR组小鼠表皮组织中Vγ5TCR、IGF-Ⅰ、KGF的mRNA表达均明显上调（ t值分别为4.52、15.24、9.43， P<0.05）；4组小鼠表皮组织中IL-15的mRNA表达总体相近（ P>0.05）。与单纯对照组相比，单纯Vγ4T细胞清除组表皮组织中NKG2D、Rae1的mRNA表达均明显上调（ t值分别为3.67、47.40， P<0.05），对照+1次UVR组小鼠表皮组织中NKG2D、Mult1、Rae1的mRNA表达均明显上调（ t值分别为5.30、6.50、9.16， P<0.05）；与单纯Vγ4T细胞清除组相比，Vγ4T细胞清除+1次UVR组小鼠表皮组织中NKG2D、H60、Mult1、Rae1的mRNA表达均明显下调（ t值分别为4.57、4.13、4.67、27.36， P<0.05）；与对照+1次UVR组相比，Vγ4T细胞清除+1次UVR组小鼠表皮组织中NKG2D、H60、Mult1、Rae1的mRNA表达均明显下调（ t值分别为5.77、8.18、12.90、8.08， P<0.05）。 结论:清除Vγ4T细胞有利于DETC增殖和毒性下调，可能促进UVR后小鼠表皮损伤修复 。

作为太阳光的固有成分,UV-B对植物生长发育有重要影响.随着对UV-B研究的深入,人们认识到UV-B不仅是环境胁迫因子,还是植物生长过程中的重要信号分子,适度的UV-B辐射对植物生长具有促进作用.UVR8是UV-B特有的光感受器,在植物响应UV-B过程中发挥不可替代的作用,且其功能受上、下游转录因子调节.目前,已知BBX、WRKY、MYB和PIF等多种转录因子参与调控UV-B辐射下的下胚轴伸长、主根长度、叶片大小及形态、开花周期和花青素合成等过程.该文主要综述了UVR8在UV-B信号通路中的分子机制,并对转录因子在UV-B辐射过程中的调控机理进行总结,以期为相关研究提供参考.

在植物响应紫外线B(ultraviolet-B,UV-B)的过程中,UV-B光受体UVR8(UV Resistance Locus 8)对植物的光形态建成和生长代谢等过程具有重要调控作用.为探究罗布麻属植物UV-B光受体信息,该研究通过罗布麻(Apocynum venetumn)和大麻状罗布麻(A.cannabinum)全基因组数据进行UV-B光受体UVR8的筛选与生物信息学分析,同时利用转录组数据分析UV-B胁迫处理下的UVR8基因表达模式.结果表明:(1)罗布麻有6个UVR8基因,大麻状罗布麻有5个UVR8基因,前者分布在1、7、9和11号染色体上,后者分布在1、8和9号染色体上.(2)UVR8蛋白为亲水性稳定蛋白,定位在细胞核,不存在跨膜结构和信号肽,二级结构主要由延伸链、无规则卷曲、α-螺旋和β-转角构成.AvUVR8b和AcUVR8a蛋白三级结构与拟南芥UVR8(AtUVR8)最为类似,并且与小粒咖啡(CaUVR8)和伊德斯种咖啡(CeUVR8)的亲缘关系最近.同时发现罗布麻AvUVR8b和大麻状罗布麻AcUVR8a基因和蛋白结构与AtUVR8基因及蛋白高度相似.(3)当以一定剂量UV-B(17.52 kJ·m-2·d-1)处理两种罗布麻植株时,AvUVR8b和AcUVR8a的表达量上调.据此推测在响应UV-B时,AvUVR8b基因在罗布麻中起主要作用,AeUVR8a基因在大麻状罗布麻中起主要作用.(4)顺式作用元件分析结果表明,UVR8的表达受光照、温度、水分、氧气和激素等因素的调控.该研究将为进一步研究罗布麻属UVR8的基因功能奠定基础,同时为解析罗布麻属植物适应UV-B的分子机制提供线索.

Light serves as the source of energy as well as an information signal for photosynthetic plants.During evolution,plants have acquired the ability to monitor environmental light radiation and adjust their developmental patterns to optimally utilize light energy for photosynthesis.The mechanisms of light perception and signal transduction have been comprehensively studied in past decades,mostly in a few model plants,including Arabidopsis thaliana.However,systematic analyses of the origin and evolution of core components involved in light perception and signaling are still lacking.In this study,we took advantage of the recently sequenced genomes and transcriptomes covering all the main Archaeplastida clades in the public domain to identify orthologous genes of core components involved in light perception and signaling and to reconstruct their evolutionary history.Our analyses suggested that acclimation to different distribution of light quality in new environments led to the origination of specific light signaling pathways in plants.The UVR8 (UV Resistance Locus 8) signaling pathway originated during the movement of plants from the deeper sea to shallow water and enabled plants to deal with ultraviolet B light (UV-B).After acquisition of UV-B adaptation,origination of the phytochrome signaling pathway helped plants to colonize water surface where red light became the prominent light energy source.The seedling emergence pathway,which is mediated by a combination of light and phytohormone signals that orchestrate plant growth pattern transitions,originated before the emergence of seed plants.Although cryptochromes and some key components of E3 ubiquitin ligase systems already existed before the divergence of the plant and animal kingdoms,the coevolution and optimization of light perception and downstream signal transduction components,including key transcription factors and E3 ubiquitin ligase systems,are evident during plant terrestrialization.

黄酮类物质代谢在植物抵御和适应紫外线B(UV-B)辐射变化过程中扮演重要角色.花青素作为类黄酮的一种,具有重要的药用价值和营养价值,UV-B辐射增强会诱导其合成.本文总结了近年来UV-B辐射诱导植物花青素合成的研究结果,对UV-B辐射对花青素合成的苯丙氨酸代谢、类黄酮代谢和花青素代谢阶段的影响进行归纳,发现UV-B辐射通过诱导植物结构基因和调节基因的表达调控花青素的合成.在UVR8受体接收UV-B信号后,转录因子MYB、bHLH、WD40激活PAL、CHI、CHS、F3H、DFR、ANS、UFGT等结构基因的表达.UV-B诱导拟南芥、甘蓝、水稻、红砂、莴苣、茄子、葡萄等植物中结构基因和调节基因的表达上升,促进花青素苷合成.通过研究UV-B辐射对植物花青素含量以及代谢途径的影响,为花色素的研究和开发提供新思路.

紫外线(UVR)照射可引起表皮黑素细胞数增加。曾报道小鼠在UVR照射后遮盖部位的黑素细胞亦有增生。这认为是由于UVR照射皮肤后释放一种致有丝分裂因子所致。本文作者首次在人体证实UVR引起照射和遮盖部位黑素细胞均增加。21名健康志愿者(男8,女13,年龄26～39岁),接受UVB照射。根据Melski分类,其中10例为Ⅱ型皮肤,11例为Ⅲ型或Ⅳ型皮肤。女性志愿者中无妊娠或服用避孕药者。UVB全身照射,17天内每周3次,剂量以Ⅱ型皮肤出现轻度红斑为度。照射时左臀部以不透光的黑色塑料遮盖15×15cm区域。

Non-damaging ultraviolet B (UV-B) light promotes photomorphogenic development and stress acclimation through UV-B-specific signal transduction in Arabidopsis.UV-B irradiation induces monomerization and nuclear translocation of the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8).However,it is not clear how the nuclear localization of UVR8 leads to changes in global gene expression.Here,we reveal that nuclear UVR8 governs UV-B-responsive transcriptional networks in concert with several previously known transcription factors,including ELONGATED HYPOCOTYL 5 (HY5) and PHYTOCHROME INTERACTING FACTOR 4 (PIF4).Based on the transcriptomic analysis,we identify MYB13 as a novel positive regulator in UV-B-induced cotyledon expansion and stress acclimation.MYB13 is UV-B inducible and is predominantly expressed in the cotyledons.Our results demonstrate that MYB13 protein functions as a transcription factor to regulate the expression of genes involved in auxin response and flavonoid biosynthesis through direct binding with their promoters.In addition,photoactivated UVR8 interacts with MYB13 in a UV-B-dependent manner and differentially modulates the affinity of MYB13 with its targets.Taken together,our results elucidate the cooperative function of the UV-B photoreceptor UVR8 with various transcription factors in the nucleus to orchestrate the expression of specific sets of downstream genes and,ultimately,mediate plant responses to UV-B light.

Plant UV-B responses are mediated by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8). In re-sponse to UV-B irradiation, UVR8 homodimers dissociate into monomers that bind to the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1). The in-teraction of the C27 domain in the C-terminal tail of UVR8 with the WD40 domain of COP1 is critical for UV-B sig-naling. However, the function of the last 17 amino acids (C17) of the C-terminus of UVR8, which are adjacent to C27, is unknown, although they are largely conserved in land plants. In this study, we established that Arabidopsis thaliana UVR8 C17 binds to full-length UVR8, but not to COP1, and reduces COP1 binding to the remaining portion of UVR8, including C27. We hypothesized that overexpression of C17 in a wild-type background would have a dominant negative effect on UVR8 activity;however, C17 overexpression caused strong silencing of endogenous UVR8, precluding a detailed analysis. We therefore generated YFP-UVR8N423 transgenic lines, in which C17 was deleted, to examine C17 function in-directly. YFP-UVR8N423 was more active than YFP-UVR8, suggesting that C17 inhibits UV-B signaling by attenuating binding between C27 and COP1. Our study reveals an inhibitory role for UVR8 C17 in fine-tuning UVR8–COP1 interactions during UV-B signaling.

Plants detect and respond to the proximity of competitors using light signals perceived by photoreceptor proteins.A low ratio of red to far-red radiation (R:FR ratio) is a key signal of competition that is sensed by the photoreceptor phytochrome B (phyB).Low R:FR ratios increase the synthesis of growth-related hormones,including auxin and gibberellins,promoting stem elongation and other shade-avoidance responses.Other photoreceptors that help plants to optimize their developmental configuration and resource allocation patterns in the canopy include blue light photoreceptors,such as cryptochromes and phototropins,and UV receptors,such as UVR8.All photoreceptors act by directly or indirectly controlling the activity of two major regulatory nodes for growth and development: the COP1/SPA ubiquitin E3 ligase complex and the PIF transcription factors.phyB is also an important modulator of hormonal pathways that regulate plant defense against herbivores and pathogens,including the jasmonic acid signaling pathway.In this Perspective,we discuss recent advances on the studies of the mechanisms that link photoreceptors with growth and defense.Understanding these mechanisms is important to provide a functional platform for breeding programs aimed at improving plant productivity,stress tolerance,and crop health in species of agronomic interest,and to manipulate the light environments in protected agriculture.

Light has a multitude of effects at all stages of the life cycle.It con-trols seed germination,seedling de-etiolation,flowering,and tropic movements,among others,through an array of complex signaling events.Several wavelength-specific photoreceptors perceive light:far-red/red by phytochromes(phyA-phyE);blue by cryptochromes(cry1 and cry2),phototropins(phot1 and phot2),and Zeitlupe family proteins(ZTL,FKF1,and LKP1);and UV-BbyUV RESISTANCE LO-CUS8(UVR8)(Paik and Huq,2019).