Perrotta Lara, Giordo Roberta, Francis Dennis, Rogers Hilary J, Albani Diego
Department of Agricultural Sciences, University of Sassari, Sassari, Italy.
School of Biosciences, Cardiff University, Cardiff, United Kingdom.
Front Plant Sci. 2021 Mar 12;12:652570. doi: 10.3389/fpls.2021.652570. eCollection 2021.
E2F transcription factors are key components of the RB/E2F pathway that, through the action of cyclin-dependent kinases, regulates cell cycle progression in both plants and animals. Moreover, plant and animal E2Fs have also been shown to regulate other cellular functions in addition to cell proliferation. Based on structural and functional features, they can be divided into different classes that have been shown to act as activators or repressors of E2F-dependent genes. Among the first plant E2F factors to be reported, we previously described DcE2F1, an activating E2F which is expressed in cycling carrot () cells. In this study, we describe the identification of the additional members of the E2F/DP family of , which includes four typical E2Fs, three atypical E2F/DEL genes, and three related DP genes. Expression analyses of the carrot and genes reveal distinctive patterns and suggest that the functions of some of them are not necessarily linked to cell proliferation. DcE2F1 was previously shown to transactivate an E2F-responsive promoter in transient assays but the functional role of this protein was not defined. Sequence comparisons indicate that DcE2F1 could be an ortholog of the AtE2FA factor of . Moreover, ectopic expression of the cDNA in transgenic Arabidopsis plants is able to upregulate and promotes cell proliferation, giving rise to polycotyly with low frequency, effects that are highly similar to those observed when over-expressing . These results indicate that DcE2F1 is involved in the control of cell proliferation and plays important roles in the regulation of embryo and plant development.
E2F转录因子是RB/E2F通路的关键组成部分，通过细胞周期蛋白依赖性激酶的作用，调节植物和动物的细胞周期进程。此外，植物和动物的E2F蛋白除了调节细胞增殖外，还被证明可以调节其他细胞功能。基于结构和功能特征，它们可分为不同类别，这些类别已被证明可作为E2F依赖性基因的激活剂或抑制剂。在最早报道的植物E2F因子中，我们之前描述了DcE2F1，一种在循环的胡萝卜细胞中表达的激活型E2F。在本研究中，我们描述了胡萝卜E2F/DP家族其他成员的鉴定，该家族包括四个典型的E2F、三个非典型的E2F/DEL基因和三个相关的DP基因。胡萝卜E2F和DP基因的表达分析揭示了独特的模式，并表明其中一些基因的功能不一定与细胞增殖相关。DcE2F1之前在瞬时分析中被证明可反式激活E2F反应性启动子，但该蛋白的功能作用尚未明确。序列比较表明，DcE2F1可能是拟南芥AtE2FA因子的直系同源物。此外，在转基因拟南芥植物中异位表达胡萝卜cDNA能够上调基因表达并促进细胞增殖，低频产生多子叶现象，这些效应与过表达AtE2FA时观察到的效应高度相似。这些结果表明，DcE2F1参与细胞增殖的调控，并在胚胎和植物发育的调节中发挥重要作用。
