Faculty Opinions recommendation of Repression of miR156 by miR159 Regulates the Timing of the Juvenile-to-Adult Transition in Arabidopsis.

Arabidopsis TEMPRANILLO 1 (TEM1) is a transcriptional repressor that participates in multiple flowering pathways and negatively regulates the juvenile-to-adult transition and the flowering transition. To understand the molecular basis for the site-specific regulation of FLOWERING LOCUS T (FT) by TEM1, we determined the structures of the two plant-specific DNA-binding domains in TEM1, AP2 and B3, in complex with their target DNA sequences from the FT gene 5′-untranslated region (5′-UTR), revealing the molecular basis for TEM1 specificity for its DNA targets. In vitro binding assays revealed that the combination of the AP2 and B3 binding sites greatly enhanced the overall binding of TEM1 to the FT 5′-UTR, indicating TEM1 combinatorically recognizes the FT gene 5′-UTR. We further showed that TEM1 recruits the Polycomb repressive complex 2 (PRC2) to the FT 5′-UTR. The simultaneous binding of the TEM1 AP2 and B3 domains to FT is necessary for deposition of H3K27me3 at the FT 5′-UTR and for the flowering repressor function of TEM1. Overall, our data suggest that the combinatorial recognition of FT 5′-UTR by TEM1 ensures H3K27me3 deposition to precisely regulate the floral transition.

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Characterization of E93 in neometabolous thrips Frankliniella occidentalis and Haplothrips brevitubus

PLoS ONE ◽

10.1371/journal.pone.0254963 ◽

2021 ◽

Vol 16 (7) ◽

pp. e0254963

Author(s):

Youhei Suzuki ◽

Takahiro Shiotsuki ◽

Akiya Jouraku ◽

Ken Miura ◽

Chieka Minakuchi

Keyword(s):

Larval Stage ◽

Hormonal Regulation ◽

Frankliniella Occidentalis ◽

Expression Profiles ◽

Mrna Levels ◽

Transcript Levels ◽

Adult Transition ◽

Thrips Species ◽

Insect Metamorphosis ◽

Krüppel Homolog 1

Insect metamorphosis into an adult occurs after the juvenile hormone (JH) titer decreases at the end of the juvenile stage. This generally coincides with decreased transcript levels of JH-response transcription factors Krüppel homolog 1 (Kr-h1) and broad (br), and increased transcript levels of the adult specifier E93. Thrips (Thysanoptera) develop through inactive and non-feeding stages referred to as “propupa” and “pupa”, and this type of distinctive metamorphosis is called neometaboly. To understand the mechanisms of hormonal regulation in thrips metamorphosis, we previously analyzed the transcript levels of Kr-h1 and br in two thrips species, Frankliniella occidentalis (Thripidae) and Haplothrips brevitubus (Phlaeothripidae). In both species, the transcript levels of Kr-h1 and br decreased in the “propupal” and “pupal” stages, and their transcription was upregulated by exogenous JH mimic treatment. Here we analyzed the developmental profiles of E93 in these two thrips species. Quantitative RT-PCR revealed that E93 expression started to increase at the end of the larval stage in F. occidentalis and in the “propupal” stage of H. brevitubus, as Kr-h1 and br mRNA levels decreased. Treatment with an exogenous JH mimic at the onset of metamorphosis prevented pupal-adult transition and caused repression of E93. These results indicated that E93 is involved in adult differentiation after JH titer decreases at the end of the larval stage of thrips. By comparing the expression profiles of Kr-h1, br, and E93 among insect species, we propose that the “propupal” and “pupal” stages of thrips have some similarities with the holometabolous prepupal and pupal stages, respectively.

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AstA signaling functions as an evolutionary conserved mechanism timing juvenile to adult transition

Yearbook of Paediatric Endocrinology ◽

10.1530/ey.16.1.3 ◽

2019 ◽

Author(s):

Deveci D ◽

Martin FA ◽

Leopold P ◽

Romero NM

Keyword(s):

Adult Transition

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Sugar promotes vegetative phase change in Arabidopsis thaliana by repressing the expression of MIR156A and MIR156C

eLife ◽

10.7554/elife.00260 ◽

2013 ◽

Vol 2 ◽

Cited By ~ 137

Author(s):

Li Yang ◽

Mingli Xu ◽

Yeonjong Koo ◽

Jia He ◽

R Scott Poethig

Keyword(s):

Arabidopsis Thaliana ◽

Phase Change ◽

Nutrient Availability ◽

Developmental Timing ◽

Vegetative Phase ◽

Adult Transition ◽

Vegetative Phase Change ◽

Exogenous Glucose ◽

Exogenous Sugar ◽

Signaling Activity

Nutrients shape the growth, maturation, and aging of plants and animals. In plants, the juvenile to adult transition (vegetative phase change) is initiated by a decrease in miR156. In Arabidopsis, we found that exogenous sugar decreased the abundance of miR156, whereas reduced photosynthesis increased the level of this miRNA. This effect was correlated with a change in the timing of vegetative phase change, and was primarily attributable to a change in the expression of two genes, MIR156A and MIR156C, which were found to play dominant roles in this transition. The glucose-induced repression of miR156 was dependent on the signaling activity of HEXOKINASE1. We also show that the defoliation-induced increase in miR156 levels can be suppressed by exogenous glucose. These results provide a molecular link between nutrient availability and developmental timing in plants, and suggest that sugar is a component of the leaf signal that mediates vegetative phase change.

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Age-Related Changes in Thymic Central Tolerance

Frontiers in Immunology ◽

10.3389/fimmu.2021.676236 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jayashree Srinivasan ◽

Jessica N. Lancaster ◽

Nandini Singarapu ◽

Laura P. Hale ◽

Lauren I. R. Ehrlich ◽

...

Keyword(s):

T Cells ◽

Negative Selection ◽

Thymic Epithelial Cells ◽

Central Tolerance ◽

Adult Transition ◽

Treg Function ◽

Age Related ◽

And Function ◽

Antigen Presenting ◽

Age Related Changes

Thymic epithelial cells (TECs) and hematopoietic antigen presenting cells (HAPCs) in the thymus microenvironment provide essential signals to self-reactive thymocytes that induce either negative selection or generation of regulatory T cells (Treg), both of which are required to establish and maintain central tolerance throughout life. HAPCs and TECs are comprised of multiple subsets that play distinct and overlapping roles in central tolerance. Changes that occur in the composition and function of TEC and HAPC subsets across the lifespan have potential consequences for central tolerance. In keeping with this possibility, there are age-associated changes in the cellular composition and function of T cells and Treg. This review summarizes changes in T cell and Treg function during the perinatal to adult transition and in the course of normal aging, and relates these changes to age-associated alterations in thymic HAPC and TEC subsets.

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