A New FronTIR in Targeted Protein Degradation and Plant Development

Three papers, two in a recent issue of Nature and one in the July issue of Developmental Cell, identify a family of F box proteins as the long-sought receptors for the plant growth hormone auxin. The new studies reveal that auxin, a small molecule, regulates F box proteins, which are involved in ubiquitin-mediated protein degradation. This finding has profound implications for understanding plant physiology and development and for defining new modes of regulation of SCF ubiquitin ligase complexes

Original Article

本研究の目的は,健康な小児ががんや白血病といった病名からどのようなイメージを抱くのか,自分が大きな病気になったとしたら,病名や治療などについて教えて欲しいと思っているのかを明らかにすることである。千葉県内の小中高校に通っている小学校5年生から高校3年生までの児童生徒1964名から得られたアンケートの回答を,統計ソフトSPSSにて分析を行い以下の結果を得た。1.健康な小児が抱くがんのイメージは,「死ぬ・治らない」「重い・危険・苦しい」といった悲観的なのものが多く,全体の約65%を占めていた。「聞いたことがない・わからない」と答えたものもおり全体の約15%であり,どの学年でも同様の傾向であった。2.健康な小児が抱く白血病のイメージは「病態や特徴について」「原因や治療について」といったものが,全体の約38%を占めていた。「聞いたことがない・わからない」と答えたものは全体の約33%を占め,小学生では半数以上が「聞いたことがない・わからない」と答えていた。3.自分が病気になったときにされる説明については小学生の80%,中学生の85%,高校生の91%が真実を伝えられることを求めていた。その理由として自分の知る権利,治療に前向きに取り組めるといった姿勢の向上,知らないことが不安になる,残された命を有意義に悔いのないように過ごしたいといったものがあげられていた。The purposes of this study were to identify the images of healthy children on cancer and leukemia, and the way of thinking of truth telling with disease. The number of subjects were 1964. They belonged to between the fifth grade of primary school and the third year in high school. They answered someitem-questionnaire, and the answers were analyzed using SPSS. The results were as follows: 1. Sixty-five percent of the images of cancer were pessimistic, like death or incurable and serious or painful . About fifteen percent were having no images. 2. Thirty-eight percent of the images of leukemia were the feature and the cause or the treatment . About thirty-three percent were having no images. 3. Truth telling was desired by eighty percent of students of primary schools, eighty-five percent of junior high schools and ninety-one percent of a high school. The reasons were the rights to know , to be patient with treatments , to become more anxious without truth telling , and to live the remaining days without regrets

PIF Genes Mediate the Effect of Sucrose on Seedling Growth Dynamics

As photoautotrophs, plants can use both the form and amount of fixed carbon as a measure of the light environment. In this study, we used a variety of approaches to elucidate the role of exogenous sucrose in modifying seedling growth dynamics. In addition to its known effects on germination, high-resolution temporal analysis revealed that sucrose could extend the number of days plants exhibited rapid hypocotyl elongation, leading to dramatic increases in ultimate seedling height. In addition, sucrose changed the timing of daily growth maxima, demonstrating that diel growth dynamics are more plastic than previously suspected. Sucrose-dependent growth promotion required function of multiple phytochrome-interacting factors (PIFs), and overexpression of PIF5 led to growth dynamics similar to plants exposed to sucrose. Consistent with this result, sucrose was found to increase levels of PIF5 protein. PIFs have well-established roles as integrators of response to light levels, time of day and phytohormone signaling. Our findings strongly suggest that carbon availability can modify the known photomorphogenetic signaling network

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

Auxin plays a role in nearly every aspect of a plant's life. Signals from the developmental program, physiological status, and encounters with other organisms all converge on the auxin pathway. The molecular mechanisms facilitating these interactions are diverse; yet, common themes emerge. Auxin can be regulated by modulating rates of biosynthesis, conjugation, and transport, as well as sensitivity of a cell to the auxin signal. In this article, we describe some well-studied examples of auxin's interactions with other pathways

Bipartite Promoter Element Required for Auxin Response1[C][W][OA]

Multiple mechanisms have been described for coordination of responses to the plant hormones auxin and brassinosteroids (Zhang et al., 2009). One unexplained phenomenon is the reliance of the auxin transcriptional response on a functional brassinosteroid pathway. In this study, we used luciferase reporters to interrogate the promoter of SMALL AUXIN-UP RNA15 (SAUR15), a well-characterized auxin and brassinosteroid early response gene in Arabidopsis (Arabidopsis thaliana). After identifying a minimal region sufficient for auxin response, we targeted predicted cis-regulatory elements contained within this sequence and found a critical subset required for hormone response. Specifically, reporter sensitivity to auxin treatment required two elements: a Hormone Up at Dawn (HUD)-type E-box and an AuxRE-related TGTCT element. Reporter response to brassinosteroid treatment relied on the same two elements. Consistent with these findings, the transcription factors BRASSINOSTEROID INSENSITIVE1-EMS SUPPESSOR1 and MONOPTEROS (MP)/ AUXIN RESPONSE FACTOR5 (ARF5) showed enhanced binding to the critical promoter region containing these elements. Treatment with auxin or brassinosteroids could enhance binding of either transcription factor, and brassinosteroid enhancement of MP/ARF5 binding required an intact HUD element. Conservation of clustered HUD elements and AuxRE-related sequences in promoters of putative SAUR15 orthologs in a number of flowering plant species, in combination with evidence for statistically significant clustering of these elements across all Arabidopsis promoters, provided further evidence of the functional importance of coordinated transcription factor binding

Building a pipeline to identify and engineer constitutive and repressible promoters

To support the increasingly complex circuits needed for plant synthetic biology applications, additional constitutive promoters are essential. Reusing promoter parts can lead to difficulty in cloning, increased heterogeneity between transformants, transgene silencing and trait instability. We have developed a pipeline to identify genes that have stable expression across a wide range of Arabidopsis tissues at different developmental stages and have identified a number of promoters that are well expressed in both transient (Nicotiana benthamiana) and stable (Arabidopsis) transformation assays. We have also introduced two genome-orthogonal gRNA target sites in a subset of the screened promoters, converting them into NOR logic gates. The work here establishes a pipeline to screen for additional constitutive promoters and can form the basis of constructing more complex information processing circuits in the future

New mechanistic links between sugar and hormone signalling networks

Plant growth and development must be coordinated with metabolism, notably with the efficiency of photosynthesis and the uptake of nutrients. This coordination requires local connections between hormonal response and metabolic state, as well as long-distance connections between shoot and root tissues. Recently, several molecular mechanisms have been proposed to explain the integration of sugar signalling with hormone pathways. In this work, DELLA and PIF proteins have emerged as hubs in sugar-hormone cross-regulation networks