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1.
Immunity ; 55(3): 385-387, 2022 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-35263564

RESUMO

Some bacteria and parasites, such as Salmonella, actively disrupt germinal centers and elicit only low affinity antibodies, but the mechanisms by which microbes alter these responses is poorly understood. In this issue of Immunity, Biram et al. (2022) uncover a mechanism by which Salmonella recruits Sca-1+ monocytes to germinal centers and impairs metabolic adaptation.


Assuntos
Infecções Bacterianas , Monócitos , Centro Germinativo/imunologia , Humanos , Salmonella
2.
Nature ; 605(7909): 349-356, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35477763

RESUMO

Although circumstantial evidence supports enhanced Toll-like receptor 7 (TLR7) signalling as a mechanism of human systemic autoimmune disease1-7, evidence of lupus-causing TLR7 gene variants is lacking. Here we describe human systemic lupus erythematosus caused by a TLR7 gain-of-function variant. TLR7 is a sensor of viral RNA8,9 and binds to guanosine10-12. We identified a de novo, previously undescribed missense TLR7Y264H variant in a child with severe lupus and additional variants in other patients with lupus. The TLR7Y264H variant selectively increased sensing of guanosine and 2',3'-cGMP10-12, and was sufficient to cause lupus when introduced into mice. We show that enhanced TLR7 signalling drives aberrant survival of B cell receptor (BCR)-activated B cells, and in a cell-intrinsic manner, accumulation of CD11c+ age-associated B cells and germinal centre B cells. Follicular and extrafollicular helper T cells were also increased but these phenotypes were cell-extrinsic. Deficiency of MyD88 (an adaptor protein downstream of TLR7) rescued autoimmunity, aberrant B cell survival, and all cellular and serological phenotypes. Despite prominent spontaneous germinal-centre formation in Tlr7Y264H mice, autoimmunity was not ameliorated by germinal-centre deficiency, suggesting an extrafollicular origin of pathogenic B cells. We establish the importance of TLR7 and guanosine-containing self-ligands for human lupus pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.


Assuntos
Mutação com Ganho de Função , Lúpus Eritematoso Sistêmico , Receptor 7 Toll-Like , Animais , Autoimunidade/genética , Linfócitos B , GMP Cíclico/análogos & derivados , Guanosina , Humanos , Lúpus Eritematoso Sistêmico/genética , Camundongos , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/metabolismo
3.
Plant Cell ; 33(6): 1980-1996, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-33764452

RESUMO

MicroRNAs (miRNAs) control various biological processes by repressing target mRNAs. In plants, miRNAs mediate target gene repression via both mRNA cleavage and translational repression. However, the mechanism underlying this translational repression is poorly understood. Here, we found that Arabidopsis thaliana HYPONASTIC LEAVES1 (HYL1), a core component of the miRNA processing machinery, regulates miRNA-mediated mRNA translation but not miRNA biogenesis when it localized in the cytoplasm. Cytoplasmic HYL1 localizes to the endoplasmic reticulum and associates with ARGONAUTE1 (AGO1) and ALTERED MERISTEM PROGRAM1. In the cytoplasm, HYL1 monitors the distribution of AGO1 onto polysomes, binds to the mRNAs of target genes, represses their translation, and partially rescues the phenotype of the hyl1 null mutant. This study uncovered another function of HYL1 and provides insight into the mechanism of plant gene regulation.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas Argonautas/metabolismo , MicroRNAs/genética , Proteínas de Ligação a RNA/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas Argonautas/genética , Carboxipeptidases/genética , Carboxipeptidases/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Citoplasma/genética , Citoplasma/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas , Biossíntese de Proteínas/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Proteínas de Ligação a RNA/metabolismo
4.
Plant Cell Environ ; 46(11): 3405-3419, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37564020

RESUMO

Brassica crops include various edible vegetable and plant oil crops, and their production is limited by low temperature beyond their tolerant capability. The key regulators of low-temperature resistance in Brassica remain largely unexplored. To identify posttranscriptional regulators of plant response to low temperature, we performed small RNA profiling, and found that 16 known miRNAs responded to cold treatment in Brassica rapa. The cold response of seven of those miRNAs were further confirmed by qRT-PCR and/or northern blot analyses. In parallel, a genome-wide association study of 220 accessions of Brassica napus identified four candidate MIRNA genes, all of which were cold-responsive, at the loci associated with low-temperature resistance. Specifically, these large-scale data analyses revealed a link between miR1885 and the plant response to low temperature in both B. rapa and B. napus. Using 5' rapid amplification of cDNA ends approach, we validated that miR1885 can cleave its putative target gene transcripts, Bn.TIR.A09 and Bn.TNL.A03, in B. napus. Furthermore, overexpression of miR1885 in Semiwinter type B. napus decreased the mRNA abundance of Bn.TIR.A09 and Bn.TNL.A03 and resulted in increased sensitivity to low temperature. Knocking down of miR1885 in Spring type B. napus led to increased mRNA abundance of its targets and improved rapeseed tolerance to low temperature. Together, our results suggested that the loci of miR1885 and its targets could be potential candidates for the molecular breeding of low temperature-tolerant Spring type Brassica crops.


Assuntos
Brassica napus , Brassica rapa , Brassica , MicroRNAs , Brassica napus/genética , Brassica rapa/genética , Brassica/genética , Estudo de Associação Genômica Ampla , Multiômica , Temperatura , MicroRNAs/genética , RNA Mensageiro , Regulação da Expressão Gênica de Plantas
5.
Opt Express ; 31(5): 8005-8019, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36859919

RESUMO

The accuracy of the spectral reflectance estimation approaches highly depends on the amount, coverage, and representation of valid samples in the training dataset. We present a dataset artificial augmentation approach with a small number of actual training samples by light source spectra tuning. Then, the reflectance estimation process is carried out with our augmented color samples for commonly used datasets (IES, Munsell, Macbeth, Leeds). Finally, the impact of the augmented color sample number is investigated using different augmented color sample numbers. The results show that our proposed approach can artificially augment the color samples from CCSG 140 color samples to 13791 color samples and even more. The reflectance estimation performances with augmented color samples are much higher than with the benchmark CCSG datasets for all tested datasets (IES, Munsell, Macbeth, Leeds, as well as a real-scene hyperspectral reflectance database). It indicates that the proposed dataset augmentation approach is practical for improving the reflectance estimation performances.

6.
Ecotoxicol Environ Saf ; 267: 115634, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37897978

RESUMO

Arsenic (As) is a notorious toxic contamination in marine environments, while the toxicity and health risk of As is highly dependent on As species in seafoods. In this study, we hypothesized that the species-specific As bioaccumulation and species resulted in species-specific healthy risk of As in seaweeds. To test the hypothesis, we collected 10 common edible seaweeds from the coast of Hainan Island in South China Sea. Then we comparatively quantified concentration of total As and 5 major As species [AsB, DMA, MMA, As(III), and As(V)] in seaweeds. The results revealed that the concentrations of total As varied significantly among 10 seaweed species. Specially, the highest total As concentration were found in brown seaweeds, followed by red seaweeds, and green seaweeds. Furthermore, the percentage of 5 As species to total As differed significantly among 10 seaweeds. The percentage of AsB was highest in Caulerpa lentillifera (53%) and lowest in Sargassum oligocystum (13%), while that of As(V) was lowest in Caulerpa lentillifera (21%) and highest in Sargassum oligocystum (81%). The iAs [As(III) + As(V)] exhibited highest value in brown seaweeds and least value in green seaweeds. The potential human health risk assessment indicated that the consumption of brown seaweeds of Sargassum oligocystum and Sargassum polycystum could cause a considerable carcinogenic risk and non-carcinogenic risk to residents. Overall, our findings here largely validated our hypothesis that the species-specific As bioaccumulation and As species had great significance to healthy risk of As in seaweeds.


Assuntos
Arsênio , Sargassum , Alga Marinha , Humanos , Arsênio/toxicidade , Bioacumulação , China , Medição de Risco
7.
Int J Mol Sci ; 24(11)2023 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-37298626

RESUMO

The overuse of copper-based fertilizers and pesticides over the last few decades has resulted in detrimental risks to our environment. Nano-enabled agrichemicals with a high effective utilization ratio have shown great potential for maintaining or minimizing environmental issues in agriculture. Copper-based nanomaterials (Cu-based NMs) serve as a promising alternative to fungicides. Three types of Cu-based NMs with different morphologies were analyzed for their different antifungal effects on Alternaria alternata in this current study. Compared to commercial copper hydroxide water power (Cu(OH)2 WP), all tested Cu-based NMs, including cuprous oxide nanoparticles (Cu2O NPs), copper nanorods (Cu NRs) and copper nanowires (Cu NWs), especially Cu2O NPs and Cu NWs, showed higher antifungal activity against Alternaria alternata. Its EC50 were 104.24 and 89.40 mg L-1, respectively, achieving comparable activity using a dose approximately 1.6 and 1.9-fold lower. Cu-based NMs could introduce the downregulation of melanin production and soluble protein content. In contrast to trends in antifungal activity, Cu2O NPs showed the strongest power in regulating melanin production and protein content and similarly exhibited the highest acute toxicity to adult zebrafish compared to other Cu-based NMs. These results demonstrate that Cu-based NMs could offer great potential in plant disease management strategies.


Assuntos
Cobre , Nanoestruturas , Animais , Cobre/química , Antifúngicos/farmacologia , Peixe-Zebra/metabolismo , Melaninas , Alternaria/metabolismo
8.
J Exp Bot ; 72(10): 3540-3553, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33606883

RESUMO

MicroRNA319a (miR319a) controls cell division arrest in plant leaves by inhibiting the expression of TCP (TEOSINTE BRANCHED 1/CYCLOIDEA/PCF) family genes. However, it is unclear whether miR319a influences infection by necrotrophic pathogens and host susceptibility. In this study, we revealed that miR319a affects plant resistance to stem rot disease caused by Sclerotinia sclerotiorum. In Brassica rapa plants infected with S. sclerotiorum, miR319a levels increased while the expression levels of several BraTCP genes significantly decreased compared with those of uninfected plants. Overexpression of BraMIR319a in B. rapa increased the susceptibility of the plants to S. sclerotiorum and aggravated stem rot disease, whereas overexpression of BraTCP4-1 promoted plant resistance. RNA sequencing data revealed a potential relationship between miR319a and pathogen-related WRKY genes. Chromatin immunoprecipitation, electrophoretic mobility shift, and reporter transaction assays showed that BraTCP4-1 could bind to the promoters of WRKY75, WRKY70, and WRKY33 and directly activate these pathogen-related genes. Moreover, the expression levels of WRKY75, WRKY70, and WRKY33 in plants overexpressing BraMIR319a decreased significantly, whereas those of plants overexpressing BraTCP4-1 increased significantly, relative to the wild type. These results suggest that miR319a and its target gene BraTCP4 control stem rot resistance through pathways of WRKY genes.


Assuntos
Ascomicetos/patogenicidade , Brassica rapa/genética , Resistência à Doença , MicroRNAs , Doenças das Plantas , Brassica rapa/microbiologia , Resistência à Doença/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , RNA de Plantas
9.
Plant Physiol ; 181(1): 208-220, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31248965

RESUMO

The internal boundary between inner and outer microsporangia within anthers is essential for male fertility of vascular plants. Dehiscence zones embedded in the boundary release pollen for fertilization. However, the molecular mechanism underlying boundary formation in anthers remains poorly understood. Here, we report that microRNA166 (miR166) and its target PHABULOSA (PHB) regulate SPOROCYTELESS/NOZZLE (SPL/NZZ), which controls microsporogenesis. In developing anthers of Arabidopsis (Arabidopsis thaliana), the expression domains of miR165/6 and SPL/NZZ are overlapped and rearranged synchronously. Dominant mutation of PHB suppresses SPL/NZZ expression on the adaxial sides of stamens, resulting in a thickened boundary, whereas activation of MIR166g up-regulates SPL/NZZ expression, leading to ectopic microsporogenesis in the boundary. PHB limits the expression domains of SPL/NZZ to facilitate construction of the boundary, while miR166 preserves the expression domains of SPL/NZZ by inhibiting PHB to allow the inner microsporangia to take shape. Subsequently, PHB activates the key stem cell maintainer WUSCHEL in anthers to restrict the stomium cells to the boundary so that dehiscence zones develop and release pollen properly. These findings link adaxial/abaxial polarity to microsporogenesis in building of the internal boundary of anthers and thus advance the concepts underlying the establishment of the internal structure of male organs.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Gametogênese Vegetal/genética , Proteínas de Homeodomínio/metabolismo , MicroRNAs/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Repressoras/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Flores/genética , Flores/crescimento & desenvolvimento , Flores/fisiologia , Proteínas de Homeodomínio/genética , MicroRNAs/genética , Mutação , Proteínas Nucleares/genética , Pólen/genética , Pólen/crescimento & desenvolvimento , Pólen/fisiologia , Proteínas Repressoras/genética
10.
Plant Physiol ; 177(2): 490-503, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29686057

RESUMO

Leaf traits affect plant agronomic performance; for example, leaf hair number provides a morphological indicator of drought and insect resistance. Brassica rapa crops have diverse phenotypes, and many B. rapa single-nucleotide polymorphisms (SNPs) have been identified and used as molecular markers for plant breeding. However, which SNPs are functional for leaf hair traits and, therefore, effective for breeding purposes remains unknown. Here, we identify a set of SNPs in the B. rapa ssp. pekinenesis candidate gene BrpHAIRY LEAVES1 (BrpHL1) and a number of SNPs of BrpHL1 in a natural population of 210 B. rapa accessions that have hairy, margin-only hairy, and hairless leaves. BrpHL1 genes and their orthologs and paralogs have many SNPs. By intensive mutagenesis and genetic transformation, we selected the functional SNPs for leaf hairs by the exclusion of nonfunctional SNPs and the orthologous and paralogous genes. The residue tryptophan-92 of BrpHL1a was essential for direct interaction with GLABROUS3 and, thus, necessary for the formation of leaf hairs. The accessions with the functional SNP leading to substitution of the tryptophan-92 residue had hairless leaves. The orthologous BrcHL1b from B. rapa ssp. chinensis regulates hair formation on leaf margins rather than leaf surfaces. The selected SNP for the hairy phenotype could be adopted as a molecular marker for insect resistance in Brassica spp. crops. Moreover, the procedures optimized here can be used to explain the molecular mechanisms of natural variation and to facilitate the molecular breeding of many crops.


Assuntos
Brassica rapa/genética , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Polimorfismo de Nucleotídeo Único , Alelos , Proteínas de Arabidopsis/genética , Brassica rapa/fisiologia , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Melhoramento Vegetal/métodos , Folhas de Planta/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Triptofano/genética
11.
BMC Plant Biol ; 18(1): 127, 2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-29925322

RESUMO

BACKGROUND: Numerous regulatory genes participate in plant thermotolerance. In Arabidopsis, HEAT-INDUCED TAS1 TARGET2 (HTT2) is an important thermotolerance gene that is silenced by ta-siR255, a trans-acting siRNA. ta-siR255 is absent from heading Chinese cabbage (Brassica rapa ssp. pekinensis). Our previous attempt to overexpress the endogenous BrpHTT2 gene of heading Chinese cabbage (B. rapa ssp. pekinensis) failed because of cosuppression. In theory, heading Chinese cabbage can overexpress Arabidopsis HTT2 to improve thermotolerance in the absence of ta-siR255-mediated gene silencing and the weak potential of coexpression. RESULTS: To test the potential application of HTT2 in improving crop thermotolerance, we transferred p35S::HTT2 to heading Chinese cabbage. We tested the leaf electrical conductivity, hypocotyl elongation, and survival percentage of p35S::HTT2 plants subjected to high-temperature (38 °C) and heat-shock (46 °C) treatment. The leaf electrical conductivity of p35S::HTT2 seedlings under high temperature decreased but did negligibly change under heat shock. The hypocotyl length of p35S::HTT2 seedlings increased under high temperature and heat shock. The survival rate of p35S::HTT2 seedlings increased under heat shock. BrpHsfs, a subset of heat-shock factor genes, were upregulated in p35S::HTT2 plants under high-temperature and heat shock conditions. In the field, transgenic plants with HTT2 appeared greener and formed leafy heads earlier than wild-type plants. CONCLUSIONS: Exogenous HTT2 increased the survival rates of heat-shocked heading Chinese cabbage by promoting thermotolerance through decreasing electrical conductivity and extending hypocotyl length. Our work provides a new approach to the genetic manipulation of thermotolerance in crops through the introduction of exogenous thermotolerance genes.


Assuntos
Proteínas de Arabidopsis/genética , Brassica rapa/fisiologia , Genes de Plantas , Proteínas Nucleares/fisiologia , Proteínas de Plantas/genética , Termotolerância/genética , Arabidopsis , Proteínas de Arabidopsis/fisiologia , Brassica rapa/genética , Resposta ao Choque Térmico , Temperatura Alta , Hipocótilo/crescimento & desenvolvimento , Proteínas Nucleares/genética , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase em Tempo Real , Plântula/genética , Plântula/fisiologia , Termotolerância/fisiologia
12.
J Autoimmun ; 81: 1-12, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28438433

RESUMO

Engagement of inhibitory receptors by cognate host MHC-I molecules triggers NK cell education, resulting in functional maturation and allowing NK cells to sense missing-self. However, NK cells also express inhibitory receptors for non-MHC-I ligands and their role in NK cell education is poorly understood. TIGIT is a recently identified inhibitory receptor that recognizes a non-MHC-I ligand CD155. Here, we demonstrated that TIGIT+ NK cells from wild-type mice exerted augmented responsiveness to various stimuli, including targets that lacked expression of CD155 ligand. TIGIT+ NK cells derived from CD155-deficient hosts, however, exhibited functional impairment, indicating that the engagement of TIGIT receptor by host CD155 promoted NK cell functional maturation. Furthermore, TIGIT deficiency impaired NK cell-mediated missing-self recognition and rejection of CD155- targets, such as allogenic splenocytes and certain tumor cells, in an MHC-I-independent and CD226-unrelated manner. Thus, TIGIT-CD155 pathway is also involved in the acquisition of optimal NK cell effector function, representing a novel MHC-I-independent education mechanism for NK cell tolerance and activation.


Assuntos
Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Receptores Imunológicos/metabolismo , Animais , Antígenos de Diferenciação de Linfócitos T/metabolismo , Biomarcadores , Citotoxicidade Imunológica/genética , Citotoxicidade Imunológica/imunologia , Expressão Gênica , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Camundongos , Camundongos Knockout , Ligação Proteica , Receptores Imunológicos/genética , Receptores Virais/genética , Receptores Virais/metabolismo , Transdução de Sinais
13.
Plant Cell ; 26(4): 1764-1780, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24728648

RESUMO

Many heat stress transcription factors (Hsfs) and heat shock proteins (Hsps) have been identified to play important roles in the heat tolerance of plants. However, many of the key factors mediating the heat response pathways remain unknown. Here, we report that two genes, which are targets of TAS1 (trans-acting siRNA precursor 1)-derived small interfering RNAs that we named HEAT-INDUCED TAS1 TARGET1 (HTT1) and HTT2, are involved in thermotolerance. Microarray analysis revealed that the HTT1 and HTT2 genes were highly upregulated in Arabidopsis thaliana seedlings in response to heat shock. Overexpression of TAS1a, whose trans-acting small interfering RNAs target the HTT genes, elevated accumulation of TAS1-siRNAs and reduced expression levels of the HTT genes, causing weaker thermotolerance. By contrast, overexpression of HTT1 and HTT2 upregulated several Hsf genes, leading to stronger thermotolerance. In heat-tolerant plants overexpressing HsfA1a, the HTT genes were upregulated, especially at high temperatures. Meanwhile, HsfA1a directly activated HTT1 and HTT2 through binding to their promoters. HTT1 interacted with the heat shock proteins Hsp70-14 and Hsp40 and NUCLEAR FACTOR Y, SUBUNIT C2. Taken together, these results suggest that HTT1 mediates thermotolerance pathways because it is targeted by TAS1a, mainly activated by HsfA1a, and acts as cofactor of Hsp70-14 complexes.

14.
Plant Biotechnol J ; 14(3): 905-14, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26250982

RESUMO

Several oilseed and vegetable crops of Brassica are biennials that require a prolonged winter cold for flowering, a process called vernalization. FLOWERING LOCUS C (FLC) is a central repressor of flowering. Here, we report that the overexpression of natural antisense transcripts (NATs) of Brassica rapa FLC (BrFLC) greatly shortens plant growth cycles. In rapid-, medium- and slow-cycling crop types, there are four copies of the BrFLC genes, which show extensive variation in sequences and expression levels. In Bre, a biennial crop type that requires vernalization, five NATs derived from the BrFLC2 locus are rapidly induced under cold conditions, while all four BrFLC genes are gradually down-regulated. The transgenic Bre lines overexpressing a long NAT of BrFLC2 do not require vernalization, resulting in a gradient of shortened growth cycles. Among them, a subset of lines both flower and set seeds as early as Yellow sarson, an annual crop type in which all four BrFLC genes have non-sense mutations and are nonfunctional in flowering repression. Our results demonstrate that the growth cycles of biennial crops of Brassica can be altered by changing the expression levels of BrFLC2 NATs. Thus, BrFLC2 NATs and their transgenic lines are useful for the genetic manipulation of crop growth cycles.


Assuntos
Brassica/crescimento & desenvolvimento , Brassica/genética , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/genética , Genes de Plantas , Proteínas de Plantas/genética , RNA Antissenso/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Temperatura Baixa , Regulação para Baixo/genética , Flores/fisiologia , Regulação da Expressão Gênica de Plantas , Família Multigênica , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , RNA Antissenso/metabolismo , Regulação para Cima/genética
15.
Nucleic Acids Res ; 42(19): 12224-36, 2014 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-25294831

RESUMO

MicroRNA (miRNA) plays an important role in the control of gene expression. HYPONASTIC LEAVES1 (HYL1) is a double-stranded RNA-binding protein that forms a complex with DICER-LIKE1 (DCL1) and SERRATE (SE) to process primary miRNA (pri-miRNA) into mature miRNA. Although HYL1 has been shown to partner with DCL1 to enhance miRNA accuracy, the mechanism by which HYL1 selects the DCL1-targeted cleavage sites in pri-miRNA has remained unknown. By mutagenesis of HYL1 and analysis of in vivo pri-miRNA processing, we investigated the role of HYL1 in pri-miRNA cleavage. HYL1 forms homodimers in which the residues Gly147 and Leu165 in the dsRBD2 domain are shown to be critical. Disruption of HYL1 homodimerization causes incorrect cleavage at sites in pri-miRNA without interrupting the interaction of HYL1 with DCL1 and accumulation of pri-miRNAs in HYL1/pri-miRNA complexes, leading to a reduction in the efficiency and accuracy of miRNAs that results in strong mutant phenotypes of the plants. HYL1 homodimers may function as a molecular anchor for DCL1 to cleave at a distance from the ssRNA-dsRNA junction in pri-miRNA. These results suggest that HYL1 ensures the correct selection of pri-miRNA cleavage sites through homodimerization and thus contributes to gene silencing and plant development.


Assuntos
Proteínas de Arabidopsis/química , MicroRNAs/metabolismo , Processamento Pós-Transcricional do RNA , Proteínas de Ligação a RNA/química , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Dimerização , Inativação Gênica , Glicina/química , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Leucina/química , Proteínas de Membrana/metabolismo , Multimerização Proteica , Estrutura Terciária de Proteína , Clivagem do RNA , Proteínas de Ligação a RNA/metabolismo , Ribonuclease III/metabolismo , Proteínas Serrate-Jagged
16.
Plant Physiol ; 164(2): 710-20, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24351684

RESUMO

Leafy heads of cabbage (Brassica oleracea), Chinese cabbage (Brassica rapa), and lettuce (Lactuca sativa) are composed of extremely incurved leaves. The shape of these heads often dictates the quality, and thus the commercial value, of these crops. Using quantitative trait locus mapping of head traits within a population of 150 recombinant inbred lines of Chinese cabbage, we investigated the relationship between expression levels of microRNA-targeted Brassica rapa ssp. pekinensis TEOSINTE BRANCHED1, cycloidea, and PCF transcription factor4 (BrpTCP4) genes and head shape. Here, we demonstrate that a cylindrical head shape is associated with relatively low BrpTCP4-1 expression, whereas a round head shape is associated with high BrpTCP4-1 expression. In the round-type Chinese cabbage, microRNA319 (miR319) accumulation and BrpTCP4-1 expression decrease from the apical to central regions of leaves. Overexpression of BrpMIR319a2 reduced the expression levels of BrpTCP4 and resulted in an even distribution of BrpTCP4 transcripts within all leaf regions. Changes in temporal and spatial patterns of BrpTCP4 expression appear to be associated with excess growth of both apical and interveinal regions, straightened leaf tips, and a transition from the round to the cylindrical head shape. These results suggest that the miR319a-targeted BrpTCP gene regulates the round shape of leafy heads via differential cell division arrest in leaf regions. Therefore, the manipulation of miR319a and BrpTCP4 genes is a potentially important tool for use in the genetic improvement of head shape in these crops.


Assuntos
Brassica/anatomia & histologia , Brassica/genética , Divisão Celular/genética , Genes de Plantas/genética , MicroRNAs/genética , Folhas de Planta/citologia , Folhas de Planta/genética , Sequência de Bases , Brassica/citologia , Brassica/ultraestrutura , Tamanho Celular , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Endogamia , MicroRNAs/metabolismo , Dados de Sequência Molecular , Tamanho do Órgão , Fenótipo , Filogenia , Epiderme Vegetal/citologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/ultraestrutura , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Recombinação Genética/genética , Fatores de Tempo
17.
Plant Biotechnol J ; 12(3): 312-21, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24237584

RESUMO

The leafy heads of cabbage (Brassica oleracea), Chinese cabbage (Brassica rapa ssp. pekinensis), Brussels sprouts (B. oleracea ssp. gemmifera) and lettuce (Lactuca sativa) comprise extremely incurved leaves that are edible vegetable products. The heading time is important for high quality and yield of these crops. Here, we report that BrpSPL9-2 (B. rapa ssp. pekinensis SQUAMOSA PROMOTER BINDING-LIKE 9-2), a target gene of microRNA brp-miR156, controls the heading time of Chinese cabbage. Quantitative measurements of leaf shapes, sizes, colour and curvature indicated that heading is a late adult phase of vegetative growth. During the vegetative period, miR156 levels gradually decreased from the seedling stage to the heading one, whereas BrpSPL9-2 and BrpSPL15-1 mRNAs increased progressively and reached the highest levels at the heading stage. Overexpression of a mutated miR156-resistant form of BrpSPL9-2 caused the significant earliness of heading, concurrent with shortening of the seedling and rosette stages. By contrast, overexpression of miR156 delayed the folding time, concomitant with prolongation of the seedling and rosette stages. Morphological analysis reveals that the significant earliness of heading in the transgenic plants overexpressing BrpSPL9-2 gene was produced because the juvenile phase was absent and the early adult phase shortened, whereas the significant delay of folding in the transgenic plants overexpressing Brp-MIR156a was due to prolongation of the juvenile and early adult phases. Thus, miR156 and BrpSPL9 genes are potentially important for genetic improvement of earliness of Chinese cabbage and other crops.


Assuntos
Brassica rapa/genética , Regulação da Expressão Gênica no Desenvolvimento , MicroRNAs/genética , Proteínas de Plantas/genética , Brassica rapa/crescimento & desenvolvimento , Brassica rapa/metabolismo , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Plantas Geneticamente Modificadas , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Fatores de Tempo
18.
Adv Immunol ; 162: 109-133, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38866437

RESUMO

Spontaneously formed germinal centers (GCs) have been reported in most mouse models of human autoimmune disease and autoimmune patients, and have long been considered a source of somatically-mutated and thus high affinity autoantibodies, but their role in autoimmunity is becoming increasingly controversial, particularly in the context of systemic autoimmune diseases like lupus. On the one hand, there is good evidence that some pathogenic lupus antibodies have acquired somatic mutations that increase affinity for self-antigens. On the other hand, recent studies that have genetically prevented GC formation, suggest that GCs are dispensable for systemic autoimmunity, pointing instead to pathogenic extrafollicular (EF) B-cell responses. Furthermore, several lines of evidence suggest germinal centers may in fact be somewhat protective in the context of autoimmunity. Here we review how some of the conflicting evidence arose, and current views on the role of GCs in autoimmunity, outlining mechanisms by which GC may eliminate self-reactivity. We also discuss recent advances in understanding extrafollicular B cell subsets that participate in autoimmunity.


Assuntos
Autoantígenos , Autoimunidade , Centro Germinativo , Centro Germinativo/imunologia , Humanos , Animais , Autoantígenos/imunologia , Autoanticorpos/imunologia , Linfócitos B/imunologia , Camundongos , Lúpus Eritematoso Sistêmico/imunologia , Doenças Autoimunes/imunologia , Subpopulações de Linfócitos B/imunologia
19.
Foods ; 13(4)2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38397502

RESUMO

Salting pretreatment is an effective method to improve the quality of frozen fish. This study investigated the quality changes and proteomic profile differences of frozen yellowfin tuna fillets pretreated with ultrasound-assisted salting (UAS) and static salting (SS). This study was centered on three aspects: physicochemical indicators' determination, histological observation, and proteomic analysis. The results showed that UAS significantly increased yield, salt content, and water-holding capacity (WHC), decreased total volatile base nitrogen (TVBN) compared to SS (p < 0.05), and significantly increased water in the protein matrix within myofibrils. Histological observations showed that the tissue cells in the UAS group were less affected by frozen damage, with a more swollen structure and rougher surface of myofibrils observed. Furthermore, 4D label-free proteomics revealed 56 differentially abundant proteins (DAPs) in UAS vs. NT comparison, mainly structural proteins, metabolic enzymes, proteasomes, and their subunits, which are associated with metabolic pathways such as calcium signaling pathway, gap junction, actin cytoskeletal regulation, and necroptosis, which are intimately associated with quality changes in freeze-stored tuna fillets. In brief, UAS enhances the potential for the application of salting pretreatment to improve frozen meat quality, and 4D label-free proteomics provides knowledge to reveal the potential links between quality and molecular changes in processed frozen meat to optimize future UAS meat processing.

20.
Science ; 383(6681): 413-421, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38271512

RESUMO

Age-associated B cells (ABCs) accumulate during infection, aging, and autoimmunity, contributing to lupus pathogenesis. In this study, we screened for transcription factors driving ABC formation and found that zinc finger E-box binding homeobox 2 (ZEB2) is required for human and mouse ABC differentiation in vitro. ABCs are reduced in ZEB2 haploinsufficient individuals and in mice lacking Zeb2 in B cells. In mice with toll-like receptor 7 (TLR7)-driven lupus, ZEB2 is essential for ABC formation and autoimmune pathology. ZEB2 binds to +20-kb myocyte enhancer factor 2b (Mef2b)'s intronic enhancer, repressing MEF2B-mediated germinal center B cell differentiation and promoting ABC formation. ZEB2 also targets genes important for ABC specification and function, including Itgax. ZEB2-driven ABC differentiation requires JAK-STAT (Janus kinase-signal transducer and activator of transcription), and treatment with JAK1/3 inhibitor reduces ABC accumulation in autoimmune mice and patients. Thus, ZEB2 emerges as a driver of B cell autoimmunity.


Assuntos
Autoimunidade , Linfócitos B , Diferenciação Celular , Regulação da Expressão Gênica , Lúpus Eritematoso Sistêmico , Homeobox 2 de Ligação a E-box com Dedos de Zinco , Animais , Humanos , Camundongos , Autoimunidade/genética , Linfócitos B/citologia , Linfócitos B/metabolismo , Diferenciação Celular/genética , Linhagem da Célula/genética , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Fatores de Transcrição MEF2/genética , Fatores de Transcrição MEF2/metabolismo , Homeobox 2 de Ligação a E-box com Dedos de Zinco/genética , Homeobox 2 de Ligação a E-box com Dedos de Zinco/metabolismo , Haploinsuficiência , Envelhecimento/imunologia , Modelos Animais de Doenças , Feminino
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