Dof基因家族调节植物生长发育功能的研究进展

Dof（DNA binding with one finger）蛋白是一类植物特异性转录因子,通常含有200～400个氨基酸和2个主要结构域。该家族成员的N 末端为高度保守的单锌指Dof结构域,具有与DNA和蛋白质相互作用的双重功能,其C末端的氨基酸序列则较为多变,是Dof蛋白重要的特异转录调控结构域。研究表明,Dof蛋白作为转录激活物或阻遏物参与了多方面的植物生长发育过程。随着基因组测序技术的发展,已有大量的Dof基因从植物基因组数据库中鉴定出来。该文对近年来国内外有关Dof基因家族的结构特点、全基因组鉴定、蛋白互作以及生物学功能等方面的研究进展进行综述,以期为Dof转录因子的深入研究提供参考。     

植物中的Dof 蛋白和Dof转录因子家族

Dof(DNA binding with one finger)蛋白是植物所特有的一类转录因子.其N末端保守的单锌指Dof结构域是既与DNA又和蛋白相互作用的双重功能域,识别的核心序列是AAAG;其C末端氨基酸序列较为多变,是Dof蛋白的特异转录调控结构域.Dof类转录因子在植物中发挥着多种功能.拟南芥和水稻的Dof转录因子家族为Aa、Bb、Cc、Dd 4个同源基因群,同类群间可能具有相似或相反的功能.文章就这一问题的研究进展作了介绍.     

植物Dof转录因子

Dof蛋白是单锌指结构的植物转录因子,具有一个由52个氨基酸组成的保守Dof结构域,可识别一段AAAG（或CTTT）的DNA核心序列,其C末端氨基酸序列比较多变,是Dof蛋白的特异转录调控区。本文简要介绍了Dof转录因子近年来在激素响应、光反应和物质合成等多个生理过程中发挥的重要作用。     

Dof转录因子在植物中的调控作用

DNA binding with one finger(Dof)蛋白是植物中特有的一类转录因子,自1993年在玉米中发现该转录因子到如今已有26年的历史。Dof蛋白只有一个由52个氨基酸组成的单锌指保守结构域,该结构域包含4个保守的半胱氨酸残基和一个二价锌离子,这两者都是Dof转录因子重要的组成部分,二者缺一不可,若半胱氨酸发生突变,或存在其他二价离子螯合剂都将会影响锌指结构的生成,进而使Dof蛋白不能与DNA结合,导致其丧失活性。半胱氨酸残基和Zn2+可以共价结合构成CX2CX21CX2C基序,此基序能够特异识别启动子中的AAAG(或CTTT)序列,从而激活或抑制靶基因的表达。Dof蛋白C-末端氨基酸序列的多变性导致该转录因子进化的多样性,从而在植物的生长发育过程中发挥着不同且重要的功能,如种子萌发、维管的发育和叶片极性、花和花粉发育、光周期反应、参与碳和氮的代谢、合成次生代谢产物、植物的逆境响应过程等。围绕着Dof转录因子的结构、系统进化关系、motif的组成和在植物中发挥的功能展开综述,以期为后续Dof转录因子的研究奠定相应的理论基础。     

植物Dof转录因子及其生物学功能

Dof(DNA binding with one finger)蛋白是植物特有的一类转录因子,包含一个C2-C2锌指,其N-末端保守的Dof结构域是既与DNA又和蛋白相互作用的双重功能域。在过去10多年的研究中,Dof蛋白在多种单子叶和双子叶植物中被分离。Dof蛋白作为转录的激活子或抑制子在植物的生长和发育中发挥重要作用。就Dof转录因子及其生物学功能的进展进行了综述。     

胡萝卜中DcDofD1转录因子的克隆及其对非生物逆境胁迫的响应分析

Dof(DNA-binding with one finger)转录因子是植物特有的一类转录因子,该类转录因子在植物生长发育过程中起重要作用。本试验以胡萝卜黑田五寸和君川红为试验材料,分别从中克隆获得Dc Dof D1转录因子基因。采用生物信息学方法对Dc Dof D1转录因子氨基酸组成、理化性质、进化关系进行了分析。并利用实时定量PCR方法对Dc Dof D1基因在非生物胁迫下的表达量进行了分析。结果表明,黑田五寸和君川红中的Dc Dof D1转录因子具有明显的单锌指结构,保守域的氨基酸序列比较保守。进化分析显示,Dc Dof D1属于Dof家族的D1亚族。在胡萝卜黑田五寸和君川红中,Dc Dof D1基因对高温、低温、干旱、盐等非生物胁迫有响应。而不同胡萝卜材料中,Dc Dof D1基因对非生物逆境响应的强度和速度不同。     

胡萝卜中DcDofD1转录因子基因的克隆及其对非生物逆境胁迫的响应分析

Dof (DNA-binding with one finger)转录因子是植物特有的一类转录因子,该类转录因子在植物生长发育过程中起重要作用。本实验以胡萝卜‘黑田五寸’和‘君川红’为实验材料,分别从中克隆得到DcDofD1转录因子基因。采用生物信息学方法对DcDofD1转录因子氨基酸组成、理化性质、进化关系进行了分析。并利用实时定量PCR方法对DcDofD1基因在非生物胁迫下的表达量进行了分析。结果表明‘黑田五寸’和‘君川红’中的DcDofD1转录因子具有明显的单锌指结构,保守域的氨基酸序列比较保守,进化分析显示,DcDofD1属于Dof家族的D1亚族。在胡萝卜‘黑田五寸’和‘君川红’中,DcDofD1基因对高温、低温、干旱、盐等非生物胁迫响应。而不同胡萝卜材料中,DcDofD1基因对非生物逆境响应的强度和速度不同。     

转基因PnDof30拟南芥非生物胁迫下的抗性分析

Dof(DNA-binding with one finger)转录因子是植物中特有的一类转录因子,是锌指蛋白家族中的一个具有众多成员的家族,氨基酸长度一般在200~400,含有非常保守的N端和较为多变的C端。已有研究表明,Dof转录因子家族在参与植物发育的多种生理途径和调节碳氮代谢、增加氮素的吸收与利用,提高植株抗逆能力中起着重要作用。为了探究小黑杨(Populus simonii×P.nigra)中Dof30基因的抗逆能力,本研究以转基因PnDof30拟南芥为研究对象,对干旱、盐和渗透胁迫后过表达PnDof30拟南芥株系L2和野生型拟南芥WT的生理指标进行比较。发现胁迫后拟南芥株系L2的种子萌发率、根长和鲜重等指标均高于WT;同时SOD、POD、脯氨酸含量高于WT,叶绿素和MDA含量下降;胁迫后L2中的PnDof30基因表达量显著提高。这些结果表明了PnDof30基因具有抗旱、耐盐和渗透胁迫的能力,对全面了解Dof转录因子的抗逆胁迫功能具有重要的意义。     

植物WRKY转录因子结构特点及其生物学功能

WRKY转录因子是近年来在植物中发现的N-端含有WRKYGQK高度保守氨基酸序列的新型转录调控因子, 它能够与(T)(T)TGAC(C/T)序列(W-box)发生特异性作用, 调节启动子中含W-box元件的调节基因和/或功能基因的表达, 从而参与植物的各种防卫反应, 调节植物的生长发育等。文章主要论述了植物WRKY转录因子的基本结构及其生物学功能。     

水稻WRKY转录调控因子研究进展

WRKY转录调控因子是植物中最大的转录调控因子家族之一,包含1或2个大约由60个氨基酸残基组成的高度保守的WRKY结构域。WRKY结构域的N端有严格保守的WRKYGQK氨基酸序列,其C端有锌指结构模型Cys(2)-His(2)或Cys(2)-His Cys。WRKY转录调控因子与靶基因启动子区域的DNA序列(T)TGAC(C/T)(W盒)特异性结合,调节目的基因的表达,在调控植物生长发育、物质代谢、抗病耐逆及氧化衰老过程中起重要作用。我们就有关水稻WRKY转录调控因子的结构分类及其生物学功能的研究进展做简要综述。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.