RESUMEN
Ataxia-telangiectasia (A-T) is a disease caused by mutations in the ATM gene (11q22.3-23.1) that induce neurodegeneration Sasihuseyinoglu AS et al. Pediatr Allergy Immunol Pulmonol 31(1):9-14, 2018, Teive HAG et al. Parkinsonism Relat Disord 46:3-8, 2018. Clinically, A-T is characterized by ataxia, mucocutaneous telangiectasia, immunodeficiency, and malignancy. Movement disorders have been the most described and well-studied symptoms of A-T. Other studies have reported visuospatial processing disorders, executive function disorders and emotional regulation disorders, which are clinical manifestations that characterize cerebellar cognitive affective syndrome (CCAS) Choy KR et al. Dev Dyn 247(1):33-46, 2018. To describe the neurocognitive and emotional state of pediatric patients with ataxia-telangiectasia and to discuss whether they have cerebellar cognitive affective syndrome. This observational, cross-sectional, and descriptive study included 9 patients with A-T from May 2019 to May 2021. A complete medical history was retrieved, and tests were applied to assess executive functions, visual-motor integration and abilities, language, psychological disorders, and ataxia. Six girls and 3 boys agreed to participate. The age range was 6 to 14 years. The participants included five schoolchildren and four teenagers. Eight patients presented impaired executive functioning. All patients showed some type of error in copying and tracing (distortion) in the performance of visual perceptual abilities. Emotional disorders such as anxiety and depression were observed in six patients. Eight patients presented with dyslalia and impairments in word articulation, all patients presented with ataxia, and seven patients used a wheelchair. All patients presented symptoms consistent with CCAS and had variable cognitive performance.
Asunto(s)
Ataxia Telangiectasia , Ataxia Cerebelosa , Enfermedades Cerebelosas , Masculino , Femenino , Adolescente , Humanos , Niño , Ataxia Telangiectasia/complicaciones , Estudios Transversales , Ataxia Cerebelosa/genética , Cognición/fisiologíaRESUMEN
The methylerythritol 4-phosphate (MEP) pathway is of paramount importance for generating plastidial isoprenoids. The first enzyme of the MEP pathway, 1-deoxy-D-xylulose-5-phosphate synthase (DXS), catalyzes a flux-controlling step. In plants the DXS gene family is composed of three distinct classes with non-redundant functions. Although the DXS1 and DXS2 subfamilies have been well characterized, the DXS3 subfamily has been considerably understudied. Here, we carried out in silico and functional analyses to better understand the DXS3 class. Our phylogenetic analysis showed high variation in copy number among the different DXS classes, with the apparent absence of DXS1 class in some species. We found that DXS3 subfamily emerged later than DXS1 and DXS2 and it is under less intense purifying selection. Furthermore, in the DXS3 subfamily critical amino acids positions in the thiamine pyrophosphate binding pocket are not conserved. We demonstrated that the DXS3 proteins from Arabidopsis, Maize, and Rice lack functional DXS activity. Moreover, the Arabidopsis DXS3 protein displayed distinctive sub-organellar chloroplast localization not observed in any DXS1 or DXS2 proteins. Co-expression analysis of the DXS3 from Arabidopsis showed that, unlike DXS1 and DXS2 proteins, it co-expresses with genes related to post-embryonic development and reproduction and not with primary metabolism and isoprenoid synthesis.
Asunto(s)
Plantas Modificadas Genéticamente/metabolismo , Plastidios/metabolismo , Transferasas/metabolismo , Evolución Molecular , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/fisiología , Filogenia , Plantas Modificadas Genéticamente/genética , Plastidios/genética , Transferasas/genéticaRESUMEN
Signals originating within plastids modulate organelle differentiation by transcriptionally regulating nuclear-encoded genes. These retrograde signals are also integral regulators of plant development, including leaf morphology. The clb5 mutant displays severe leaf morphology defects due to Apocarotenoid Signal 1 (ACS1) accumulation in the developmentally arrested plastid. Transcriptomic analysis of clb5 validates that ACS1 accumulation deregulates hundreds of nuclear genes, including the suppression of most genes encoding plastid ribosomal proteins. Herein, we order the molecular events causing the leaf phenotype associated with the accumulation of ACS1, which includes two consecutive retrograde signaling cascades. Firstly, ACS1 originating in the plastid drives inhibition of plastid translation (IPT) via nuclear transcriptome remodeling of chlororibosomal proteins, requiring light as an essential component. Subsequently, IPT results in leaf morphological defects via a GUN1-dependent pathway shared with seedlings undergoing chemical IPT treatments and is restricted to an early window of the leaf development. Collectively, this work advances our understanding of the complexity within plastid retrograde signaling exemplified by sequential signal exchange and consequences that in a particular temporal and spatial context contribute to the modulation of leaf development.
Asunto(s)
Carotenoides/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Plastidios/metabolismo , Transducción de Señal , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Perfilación de la Expresión Génica , Hojas de la Planta/metabolismo , Plantones/crecimiento & desarrolloRESUMEN
In addition to acting as photoprotective compounds, carotenoids also serve as precursors in the biosynthesis of several phytohormones and proposed regulatory signals. Here, we report a signaling process derived from carotenoids that regulates early chloroplast and leaf development. Biosynthesis of the signal depends on ζ-carotene desaturase activity encoded by the ζ-CAROTENE DESATURASE (ZDS)/CHLOROPLAST BIOGENESIS5 (CLB5) gene in Arabidopsis thaliana. Unlike other carotenoid-deficient plants, zds/clb5 mutant alleles display profound alterations in leaf morphology and cellular differentiation as well as altered expression of many plastid- and nucleus-encoded genes. The leaf developmental phenotypes and gene expression alterations of zds/clb5/spc1/pde181 plants are rescued by inhibitors or mutations of phytoene desaturase, demonstrating that phytofluene and/or ζ-carotene are substrates for an unidentified signaling molecule. Our work further demonstrates that this signal is an apocarotenoid whose synthesis requires the activity of the carotenoid cleavage dioxygenase CCD4.
RESUMEN
In recent years, the transcription factor ABI4 has emerged as an important node of integration for external and internal signals such as nutrient status and hormone signaling that modulates critical transitions during the growth and development of plants. For this reason, understanding the mechanism of action and regulation of this protein represents an important step towards the elucidation of crosstalk mechanisms in plants. However, this understanding has been hindered due to the negligible levels of this protein as a result of multiple posttranscriptional regulations. To better understand the function and regulation of the ABI4 protein in this work, we performed a functional analysis of several evolutionarily conserved motifs. Based on these conserved motifs, we identified ortholog genes of ABI4 in different plant species. The functionality of the putative ortholog from Theobroma cacao was demonstrated in transient expression assays and in complementation studies in plants. The function of the highly conserved motifs was analyzed after their deletion or mutagenesis in the Arabidopsis ABI4 sequence using mesophyll protoplasts. This approach permitted us to immunologically detect the ABI4 protein and identify some of the mechanisms involved in its regulation. We identified sequences required for the nuclear localization (AP2-associated motif) as well as those for transcriptional activation function (LRP motif). Moreover, this approach showed that the protein stability of this transcription factor is controlled through protein degradation and subcellular localization and involves the AP2-associated and the PEST motifs. We demonstrated that the degradation of ABI4 protein through the PEST motif is mediated by the 26S proteasome in response to changes in the sugar levels.
Asunto(s)
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Evolución Molecular , Plantas/genética , Factores de Transcripción/química , Factores de Transcripción/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Arabidopsis/química , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Núcleo Celular/genética , Núcleo Celular/metabolismo , Secuencia Conservada , Regulación de la Expresión Génica de las Plantas , Datos de Secuencia Molecular , Plantas/química , Plantas/clasificación , Plantas/metabolismo , Estabilidad Proteica , Transporte de Proteínas , Proteolisis , Factores de Transcripción/genéticaRESUMEN
Cry toxins produced by Bacillus thuringiensis bacteria are insecticidal proteins used worldwide in the control of different insect pests. Alterations in toxin-receptor interaction represent the most common mechanism to induce resistance to Cry toxins in lepidopteran insects. Cry toxins bind with high affinity to the cadherin protein present in the midgut cells and this interaction facilitates the proteolytic removal of helix α-1 and pre-pore oligomer formation. Resistance to Cry toxins has been linked with mutations in the cadherin gene. One strategy effective to overcome larval resistance to Cry1A toxins is the production of Cry1AMod toxins that lack helix α-1. Cry1AMod are able to form oligomeric structures without binding to cadherin receptor and were shown to be toxic to cadherin-silenced Manduca sexta larvae and Pectinophora gossypiella strain with resistance linked to mutations in a cadherin gene. We developed Cry1AbMod tobacco transgenic plants to analyze if Cry1AMod toxins can be expressed in transgenic crops, do not affect plant development and are able to control insect pests. Our results show that production of the Cry1AbMod toxin in transgenic plants does not affect plant development, since these plants exhibited healthy growth, produced abundant seeds, and were virtually undistinguishable from control plants. Most importantly, Cry1AbMod protein produced in tobacco plants retains its functional toxic activity against susceptible and tolerant M. sexta larvae due to the silencing of cadherin receptor by RNAi. These results suggest that CryMod toxins could potentially be expressed in other transgenic crops to protect them against both toxin-susceptible and resistant lepidopteran larvae affected in cadherin gene.
Asunto(s)
Proteínas Bacterianas , Cadherinas/antagonistas & inhibidores , Endotoxinas , Proteínas Hemolisinas , Larva/efectos de los fármacos , Manduca/efectos de los fármacos , Nicotiana/toxicidad , Control Biológico de Vectores/métodos , Hojas de la Planta/toxicidad , Plantas Modificadas Genéticamente/toxicidad , ARN Interferente Pequeño/farmacología , Animales , Bacillus thuringiensis/química , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/toxicidad , Cadherinas/metabolismo , Endotoxinas/química , Endotoxinas/genética , Endotoxinas/metabolismo , Endotoxinas/toxicidad , Expresión Génica , Silenciador del Gen , Genes Sintéticos , Proteínas Hemolisinas/química , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/toxicidad , Insecticidas/metabolismo , Insecticidas/toxicidad , Larva/fisiología , Manduca/fisiología , Mutación , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Unión Proteica , Estructura Secundaria de Proteína , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Nicotiana/genética , Nicotiana/metabolismoRESUMEN
The 1-deoxy-D-xylulose 5-phosphate synthase (DXS) enzyme catalyses the first biosynthetic step of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. In plants the MEP pathway is involved in the synthesis of the common precursors to the plastidic isoprenoids, isopentenyl diphosphate and dimethylallyl diphosphate, in plastids. DXS is recognized as limiting this pathway and is a potential target for manipulation to increase various isoprenoids such as carotenoids. In Zea mays three dxs genes exist that encode plastid-targeted functional enzymes. Evidence is provided that these genes represent phylogenetically distinctive clades conserved among plants preceding monocot-dicot divergence. There is differential accumulation for each dxs gene transcript, during development and in response to external signals such as light. At the protein level, the analysis demonstrates that in Z. mays, DXS protein is feedback regulated in response to the inhibition of the pathway flow. The results support that the multilevel regulation of DXS activity is conserved in evolution.