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1.
Proc Natl Acad Sci U S A ; 120(42): e2309616120, 2023 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-37824528

RESUMO

Biological patterns that emerge during the morphogenesis of multicellular organisms can display high precision at large scales, while at cellular scales, cells exhibit large fluctuations stemming from cell-cell differences in molecular copy numbers also called demographic noise. We study the conflicting interplay between high precision and demographic noise in trichome patterns on the epidermis of wild-type Arabidopsis thaliana leaves, as a two-dimensional model system. We carry out a statistical characterization of these patterns and show that their power spectra display fat tails-a signature compatible with noise-driven stochastic Turing patterns-which are absent in power spectra of patterns driven by deterministic instabilities. We then present a theoretical model that includes demographic noise stemming from birth-death processes of genetic regulators which we study analytically and by stochastic simulations. The model captures the observed experimental features of trichome patterns.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Tricomas/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Folhas de Planta/metabolismo
2.
J Exp Bot ; 2024 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-39377268

RESUMO

The balance between cell growth, proliferation and differentiation emerges from gene regulatory networks coupled to various signal transduction pathways, including reactive oxygen species (ROS) and transcription factors (TFs), enabling developmental responses to environmental cues. The Arabidopsis thaliana's primary root has become a valuable system for unraveling such networks. Recently, the role of TFs that mediate the ROS's inhibition of primary root growth has begun to be characterized. This study demonstrates that the MADS-box transcription factor XAANTAL1 (XAL1) is an essential regulator of hydrogen peroxide (H2O2) in primary root growth and root stem cell niche identity. Interestingly, our findings suggest that XAL1 acts as a positive regulator of H2O2 concentration in the root meristem by directly regulating genes involved in oxidative stress response, such as PEROXIDASE 28 (PER28). Moreover, we found that XAL1 is necessary for the H2O2-induced inhibition of primary root growth through the negative regulation of peroxidase and catalase activities. Furthermore, XAL1, in conjunction with RETINOBLASTOMA-RELATED (RBR), is essential for positively regulating the differentiation of columella stem cells and for participating in primary root growth inhibition in response to oxidative stress induced by H2O2 treatment.

3.
Mol Biol Rep ; 51(1): 763, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38874813

RESUMO

BACKGROUND: Arabidopsis thaliana primary root growth has become a model for evo-devo studies due to its simplicity and facility to record cell proliferation and differentiation. To identify new genetic components relevant to primary root growth, we used a Genome-Wide Association Studies (GWAS) meta-analysis approach using data published in the last decade. In this work, we performed intra and inter-studies analyses to discover new genetic components that could participate in primary root growth. METHODS AND RESULTS: We used 639 accessions from nine different studies under control conditions and performed different GWAS tests. We found that primary root growth changes were associated with 41 genes, of which six (14.6%) have been previously described as inhibitors or promoters of primary root growth. The knockdown lines of two genes, Suppressor of Gene Silencing (SGS3), involved in tasiRNA processing, and a gene with a Sterile Alpha Motif (SAM) motif named NOJOCH MOOTS (NOJO), confirmed their role as repressors of primary root growth, none has been shown to participate in this developmental process before. CONCLUSIONS: In summary, our GWAS analysis of different available studies identified new genes that participate in primary root growth; two of them were identified as repressors of primary root growth.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Estudo de Associação Genômica Ampla , Raízes de Plantas , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Estudo de Associação Genômica Ampla/métodos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Polimorfismo de Nucleotídeo Único/genética , Fenótipo , Genes de Plantas/genética
4.
Plant Physiol ; 188(2): 846-860, 2022 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-34791452

RESUMO

Arabidopsis (Arabidopsis thaliana) primary and lateral roots (LRs) are well suited for 3D and 4D microscopy, and their development provides an ideal system for studying morphogenesis and cell proliferation dynamics. With fast-advancing microscopy techniques used for live-imaging, whole tissue data are increasingly available, yet present the great challenge of analyzing complex interactions within cell populations. We developed a plugin "Live Plant Cell Tracking" (LiPlaCeT) coupled to the publicly available ImageJ image analysis program and generated a pipeline that allows, with the aid of LiPlaCeT, 4D cell tracking and lineage analysis of populations of dividing and growing cells. The LiPlaCeT plugin contains ad hoc ergonomic curating tools, making it very simple to use for manual cell tracking, especially when the signal-to-noise ratio of images is low or variable in time or 3D space and when automated methods may fail. Performing time-lapse experiments and using cell-tracking data extracted with the assistance of LiPlaCeT, we accomplished deep analyses of cell proliferation and clonal relations in the whole developing LR primordia and constructed genealogical trees. We also used cell-tracking data for endodermis cells of the root apical meristem (RAM) and performed automated analyses of cell population dynamics using ParaView software (also publicly available). Using the RAM as an example, we also showed how LiPlaCeT can be used to generate information at the whole-tissue level regarding cell length, cell position, cell growth rate, cell displacement rate, and proliferation activity. The pipeline will be useful in live-imaging studies of roots and other plant organs to understand complex interactions within proliferating and growing cell populations. The plugin includes a step-by-step user manual and a dataset example that are available at https://www.ibt.unam.mx/documentos/diversos/LiPlaCeT.zip.


Assuntos
Arabidopsis/fisiologia , Proliferação de Células , Rastreamento de Células/instrumentação , Células Vegetais/fisiologia , Desenvolvimento Vegetal , Arabidopsis/crescimento & desenvolvimento
5.
Int J Mol Sci ; 24(16)2023 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-37628953

RESUMO

Light and photoperiod are environmental signals that regulate flowering transition. In plants like Arabidopsis thaliana, this regulation relies on CONSTANS, a transcription factor that is negatively posttranslational regulated by phytochrome B during the morning, while it is stabilized by PHYA and cryptochromes 1/2 at the end of daylight hours. CO induces the expression of FT, whose protein travels from the leaves to the apical meristem, where it binds to FD to regulate some flowering genes. Although PHYB delays flowering, we show that light and PHYB positively regulate XAANTAL1 and other flowering genes in the shoot apices. Also, the genetic data indicate that XAL1 and FD participate in the same signaling pathway in flowering promotion when plants are grown under a long-day photoperiod at 22 °C. By contrast, XAL1 functions independently of FD or PIF4 to induce flowering at higher temperatures (27 °C), even under long days. Furthermore, XAL1 directly binds to FD, SOC1, LFY, and AP1 promoters. Our findings lead us to propose that light and temperature influence the floral network at the meristem level in a partially independent way of the signaling generated from the leaves.


Assuntos
Arabidopsis , Arabidopsis/genética , Febre , Meristema/genética , Fitocromo B , Temperatura , Fatores de Transcrição/genética
6.
J Exp Bot ; 73(1): 38-49, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34518884

RESUMO

Asymmetric cell divisions are essential to generate different cellular lineages. In plants, asymmetric cell divisions regulate the correct formation of the embryo, stomatal cells, apical and root meristems, and lateral roots. Current knowledge of regulation of asymmetric cell divisions suggests that, in addition to the function of key transcription factor networks, epigenetic mechanisms play crucial roles. Therefore, we highlight the importance of epigenetic regulation and chromatin dynamics for integration of signals and specification of cells that undergo asymmetric cell divisions, as well as for cell maintenance and cell fate establishment of both progenitor and daughter cells. We also discuss the polarization and segregation of cell components to ensure correct epigenetic memory or resetting of epigenetic marks during asymmetric cell divisions.


Assuntos
Divisão Celular Assimétrica , Epigênese Genética , Diferenciação Celular , Linhagem da Célula , Desenvolvimento Vegetal/genética
7.
Medicina (Kaunas) ; 58(4)2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-35454388

RESUMO

Background and Objectives: The commissural nucleus of the tractus solitarius (cNTS) not only responds to glucose levels directly, but also receives afferent signals from the liver, and from the carotid chemoreceptors (CChR). In addition, leptin, through its receptors in the cNTS, regulates food intake, body weight, blood glucose levels, and brain glucose retention (BGR). These leptin effects on cNTS are thought to be mediated through the sympathetic-adrenal system. How these different sources of information converging in the NTS regulate blood glucose levels and brain glucose retention remains largely unknown. The goal of the present study was to determine whether the local administration of leptin in cNTS alone, or after local anoxic stimulation using sodium cyanide (NaCN) in the carotid sinus, modifies the expression of leptin Ob-Rb and of c-Fos mRNA. We also investigated how leptin, alone, or in combination with carotid sinus stimulation, affected brain glucose retention. Materials and Methods: The experiments were carried out in anesthetized male Wistar rats artificially ventilated to maintain homeostatic values for pO2, pCO2, and pH. We had four groups: (a) experimental 1, leptin infusion in cNTS and NaCN in the isolated carotid sinus (ICS; n = 10); (b) experimental 2, leptin infusion in cNTS and saline in the ICS (n = 10); (c) control 1, artificial cerebrospinal fluid (aCSF) in cNTS and NaCN in the ICS (n = 10); (d) control 2, aCSF in cNTS and saline in the ICS (n = 10). Results: Leptin in cNTS, preceded by NaCN in the ICS increased BGR and leptin Ob-Rb mRNA receptor expression, with no significant increases in c-Fos mRNA in the NTSc. Conclusions: Leptin in the cNTS enhances brain glucose retention induced by an anoxic stimulus in the carotid chemoreceptors, through an increase in Ob-Rb receptors, without persistent changes in neuronal activation.


Assuntos
Corpo Carotídeo , Leptina , Receptores para Leptina , Núcleo Solitário , Animais , Glicemia/metabolismo , Corpo Carotídeo/metabolismo , Glucose/metabolismo , Hipóxia , Leptina/metabolismo , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores para Leptina/metabolismo , Núcleo Solitário/metabolismo
8.
Int J Mol Sci ; 22(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34071961

RESUMO

Flowering is one of the most critical developmental transitions in plants' life. The irreversible change from the vegetative to the reproductive stage is strictly controlled to ensure the progeny's success. In Arabidopsis thaliana, seven flowering genetic pathways have been described under specific growth conditions. However, the evidence condensed here suggest that these pathways are tightly interconnected in a complex multilevel regulatory network. In this review, we pursue an integrative approach emphasizing the molecular interactions among the flowering regulatory network components. We also consider that the same regulatory network prevents or induces flowering phase change in response to internal cues modulated by environmental signals. In this sense, we describe how during the vegetative phase of development it is essential to prevent the expression of flowering promoting genes until they are required. Then, we mention flowering regulation under suboptimal growing temperatures, such as those in autumn and winter. We next expose the requirement of endogenous signals in flowering, and finally, the acceleration of this transition by long-day photoperiod and temperature rise signals allowing A. thaliana to bloom in spring and summer seasons. With this approach, we aim to provide an initial systemic view to help the reader integrate this complex developmental process.


Assuntos
Arabidopsis/fisiologia , Flores/fisiologia , Regulação da Expressão Gênica de Plantas , Transdução de Sinais , Biomarcadores , Redes Reguladoras de Genes , Fotoperíodo , Desenvolvimento Vegetal/genética , Estações do Ano , Temperatura
9.
New Phytol ; 225(3): 1261-1272, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31545512

RESUMO

During plant development, morphogenetic processes rely on the activity of meristems. Meristem homeostasis depends on a complex regulatory network constituted by different factors and hormone signaling that regulate gene expression to coordinate the correct balance between cell proliferation and differentiation. ULTRAPETALA1, a transcriptional regulatory protein described as an Arabidopsis Trithorax group factor, has been characterized as a regulator of the shoot and floral meristems activity. Here, we highlight the role of ULTRAPETALA1 in root stem cell niche maintenance. We found that ULTRAPETALA1 is required to regulate both the quiescent center cell division rate and auxin signaling at the root tip. Furthermore, ULTRAPETALA1 regulates columella stem cell differentiation. These roles are independent of the ARABIDOPSIS TRITHORAX1, suggesting a different mechanism by which ULTRAPETALA1 can act in the root apical meristem of Arabidopsis. This work introduces a new component of the regulatory network needed for the root stem cell niche maintenance.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Raízes de Plantas/citologia , Nicho de Células-Tronco , Células-Tronco/citologia , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Ciclo Celular , Divisão Celular , Regulação da Expressão Gênica de Plantas , Histona-Lisina N-Metiltransferase , Ácidos Indolacéticos/metabolismo , Meristema/citologia , Meristema/genética , Raízes de Plantas/genética , Transdução de Sinais , Nicho de Células-Tronco/genética , Células-Tronco/metabolismo , Fatores de Transcrição/genética
10.
Int J Mol Sci ; 21(14)2020 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-32664691

RESUMO

The Retinoblastoma protein (pRb) is a key cell cycle regulator conserved in a wide variety of organisms. Experimental analysis of pRb's functions in animals and plants has revealed that this protein participates in cell proliferation and differentiation processes. In addition, pRb in animals and its orthologs in plants (RBR), are part of highly conserved protein complexes which suggest the possibility that analogies exist not only between functions carried out by pRb orthologs themselves, but also in the structure and roles of the protein networks where these proteins are involved. Here, we present examples of pRb/RBR participation in cell cycle control, cell differentiation, and in the regulation of epigenetic changes and chromatin remodeling machinery, highlighting the similarities that exist between the composition of such networks in plants and animals.


Assuntos
Proteínas de Ciclo Celular/fisiologia , Montagem e Desmontagem da Cromatina , Epigênese Genética , Proteínas de Plantas/fisiologia , Proteína do Retinoblastoma/fisiologia , Animais , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/fisiologia , Ciclo Celular/genética , Proteínas de Ciclo Celular/química , Diferenciação Celular/genética , Dano ao DNA , Genes de Plantas , Genes do Retinoblastoma , Homeostase , Mamíferos/genética , Mamíferos/metabolismo , Modelos Moleculares , Família Multigênica , Complexos Multiproteicos , Proteínas de Neoplasias/química , Proteínas de Neoplasias/fisiologia , Proteínas de Plantas/química , Plantas/genética , Plantas/metabolismo , Conformação Proteica , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Proteína do Retinoblastoma/química , Especificidade da Espécie , Células-Tronco/metabolismo
11.
New Phytol ; 223(3): 1143-1158, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30883818

RESUMO

Plant growth is largely post-embryonic and depends on meristems that are active throughout the lifespan of an individual. Developmental patterns rely on the coordinated spatio-temporal expression of different genes, and the activity of transcription factors is particularly important during most morphogenetic processes. MADS-box genes constitute a transcription factor family in eukaryotes. In Arabidopsis, their proteins participate in all major aspects of shoot development, but their role in root development is still not well characterized. In this review we synthetize current knowledge pertaining to the function of MADS-box genes highly expressed in roots: XAL1, XAL2, ANR1 and AGL21, as well as available data for other MADS-box genes expressed in this organ. The role of Trithorax group and Polycomb group complexes on MADS-box genes' epigenetic regulation is also discussed. We argue that understanding the role of MADS-box genes in root development of species with contrasting architectures is still a challenge. Finally, we propose that MADS-box genes are key components of the gene regulatory networks that underlie various gene expression patterns, each one associated with the distinct developmental fates observed in the root. In the case of XAL1 and XAL2, their role within these networks could be mediated by regulatory feedbacks with auxin.


Assuntos
Genes de Plantas , Proteínas de Domínio MADS/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/genética , Epigênese Genética , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/metabolismo , Filogenia
12.
J Musculoskelet Neuronal Interact ; 19(3): 354-361, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31475943

RESUMO

OBJECTIVE: This study aimed to examine the effects of moderate (MIT) and high-intensity training (HIT) chronic exercise on plasma tumor necrosis factor alpha (TNF-α) level and its impact on Langerhans islet morphology in healthy rats. METHODS: Two-month old normal male Wistar rats were divided into three groups: control (C, n=6), MIT (n=6), and HIT (n=4). The training protocol consisted in 24 sessions of running on a treadmill at 60-80% maximal oxygen consumption (VO2max) for MIT, and >80% VO2max for HIT. TNF-α and insulin were measured with ELISA tests. Duodenal pancreas was dissected to analyze the Langerhans islets by immunohistochemistry, a correlation analysis was performed with the nuclei/total islet area. Results: HIT and MIT rats showed lower TNF-α plasma levels than controls. Plasma insulin level decreased significantly in HIT compared with C and MIT. In addition, the islet area and nuclei density per islet were higher in the exercise groups compared with C. However, none of the groups showed PD1 immunoreactivity. CONCLUSIONS: Under healthy conditions, the chronic exercise reduced plasmatic TNF-α level, and in the same sense, increased the size of the Langerhans islets, depending to the exercise intensity.


Assuntos
Ilhotas Pancreáticas , Condicionamento Físico Animal/fisiologia , Fator de Necrose Tumoral alfa/sangue , Animais , Masculino , Ratos , Ratos Wistar
13.
J Theor Biol ; 454: 30-40, 2018 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-29857084

RESUMO

Understanding the emergence of biological structures and their changes is a complex problem. On a biochemical level, it is based on gene regulatory networks (GRN) consisting on interactions between the genes responsible for cell differentiation and coupled in a greater scale with external factors. In this work we provide a systematic methodological framework to construct Waddington's epigenetic landscape of the GRN involved in cellular determination during the early stages of development of angiosperms. As a specific example we consider the flower of the plant Arabidopsis thaliana. Our model, which is based on experimental data, recovers accurately the spatial configuration of the flower during cell fate determination, not only for the wild type, but for its homeotic mutants as well. The method developed in this project is general enough to be used in the study of the relationship between genotype-phenotype in other living organisms.


Assuntos
Flores/embriologia , Flores/genética , Modelos Genéticos , Modelos Teóricos , Organogênese Vegetal , Arabidopsis/embriologia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Padronização Corporal/genética , Diferenciação Celular/genética , Epigênese Genética , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Estudos de Associação Genética , Organogênese Vegetal/genética , Análise Espaço-Temporal
14.
PLoS Comput Biol ; 13(4): e1005488, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28426669

RESUMO

The study of the concerted action of hormones and transcription factors is fundamental to understand cell differentiation and pattern formation during organ development. The root apical meristem of Arabidopsis thaliana is a useful model to address this. It has a stem cell niche near its tip conformed of a quiescent organizer and stem or initial cells around it, then a proliferation domain followed by a transition domain, where cells diminish division rate before transiting to the elongation zone; here, cells grow anisotropically prior to their final differentiation towards the plant base. A minimal model of the gene regulatory network that underlies cell-fate specification and patterning at the root stem cell niche was proposed before. In this study, we update and couple such network with both the auxin and cytokinin hormone signaling pathways to address how they collectively give rise to attractors that correspond to the genetic and hormonal activity profiles that are characteristic of different cell types along A. thaliana root apical meristem. We used a Boolean model of the genetic-hormonal regulatory network to integrate known and predicted regulatory interactions into alternative models. Our analyses show that, after adding some putative missing interactions, the model includes the necessary and sufficient components and regulatory interactions to recover attractors characteristic of the root cell types, including the auxin and cytokinin activity profiles that correlate with different cellular behaviors along the root apical meristem. Furthermore, the model predicts the existence of activity configurations that could correspond to the transition domain. The model also provides a possible explanation for apparently paradoxical cellular behaviors in the root meristem. For example, how auxin may induce and at the same time inhibit WOX5 expression. According to the model proposed here the hormonal regulation of WOX5 might depend on the cell type. Our results illustrate how non-linear multi-stable qualitative network models can aid at understanding how transcriptional regulators and hormonal signaling pathways are dynamically coupled and may underlie both the acquisition of cell fate and the emergence of hormonal activity profiles that arise during complex organ development.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Redes Reguladoras de Genes/genética , Meristema/crescimento & desenvolvimento , Meristema/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Diferenciação Celular/genética , Diferenciação Celular/fisiologia , Biologia Computacional , Citocininas/metabolismo , Ácidos Indolacéticos/metabolismo , Meristema/citologia , Meristema/metabolismo , Modelos Biológicos , Transdução de Sinais/genética
16.
Adv Exp Med Biol ; 1071: 143-149, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30357745

RESUMO

Leptin is a protein hormone that plays a key role in the regulation of energy balance and glucose homeostasis. Leptin and all leptin receptor isoforms are present in the carotid bodies, but its precise function in glucose regulation and metabolism is not yet known. The aim of this study was to determine whether exogenous leptin, microinjected into the commissural nucleus tractus solitarii (cNTS), preceding sodium cyanide (NaCN) injection into the circulatory isolated carotid sinus (ICS), in vivo, modifies hyperglycemic reflex (HR) and brain glucose retention (BGR). In anesthetized Wistar rats (sodium pentobarbital, i.p. 3.3 mg/100 g/saline, Pfizer, Mex), arterial and venous blood samples were collected from silastic catheters implanted in the abdominal aorta and jugular sinus. Exogenous leptin (50 ng/20 nL of aCSF) or leptin vehicle (20 nL of aCSF) microinjected (stereotaxically) into the cNTS 4 min before NaCN (5 µg/100 g/50 µL saline into ICS) (experimental 1 [E1] and control 1[C1] groups, respectively) significantly increased HR and BGR compared with their basal values, but the increase was bigger in the E1 group. When leptin or aCSF were injected into the cNTS before saline (E2 and C2 groups, respectively) glucose responses did not vary when compared with their basal levels. Leptin and its receptors in the cNTS cells probably contribute to their sensitization during hypoxia.


Assuntos
Corpo Carotídeo , Células Quimiorreceptoras/metabolismo , Cianetos/efeitos adversos , Glucose/metabolismo , Leptina/farmacologia , Núcleo Solitário/metabolismo , Animais , Ratos , Ratos Wistar
17.
EMBO J ; 32(21): 2884-95, 2013 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-24121311

RESUMO

Elucidating molecular links between cell-fate regulatory networks and dynamic patterning modules is a key for understanding development. Auxin is important for plant patterning, particularly in roots, where it establishes positional information for cell-fate decisions. PIN genes encode plasma membrane proteins that serve as auxin efflux transporters; mutations in members of this gene family exhibit smaller roots with altered root meristems and stem-cell patterning. Direct regulators of PIN transcription have remained elusive. Here, we establish that a MADS-box gene (XAANTAL2, XAL2/AGL14) controls auxin transport via PIN transcriptional regulation during Arabidopsis root development; mutations in this gene exhibit altered stem-cell patterning, root meristem size, and root growth. XAL2 is necessary for normal shootward and rootward auxin transport, as well as for maintaining normal auxin distribution within the root. Furthermore, this MADS-domain transcription factor upregulates PIN1 and PIN4 by direct binding to regulatory regions and it is required for PIN4-dependent auxin response. In turn, XAL2 expression is regulated by auxin levels thus establishing a positive feedback loop between auxin levels and PIN regulation that is likely to be important for robust root patterning.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Ácidos Indolacéticos/metabolismo , Proteínas de Domínio MADS/metabolismo , Proteínas de Membrana Transportadoras/genética , Proteínas de Arabidopsis/genética , Proteínas de Domínio MADS/genética , Proteínas de Membrana Transportadoras/metabolismo , Raízes de Plantas/fisiologia
18.
Muscle Nerve ; 53(3): 446-51, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26148339

RESUMO

INTRODUCTION: Brain-derived neurotrophic factor (BDNF) protein expression is sensitive to cellular activity. In the sedentary state, BDNF expression is affected by the muscle phenotype. METHODS: Eighteen Wistar rats were divided into the following 3 groups: sedentary (S); moderate-intensity training (MIT); and high-intensity training (HIT). The training protocol lasted 8 weeks. Forty-eight hours after training, total RNA and protein levels in the soleus and plantaris muscles were obtained. RESULTS: In the plantaris, the BDNF protein level was lower in the HIT than in the S group (P < 0.05). A similar effect was found in the soleus (without significant difference). In the soleus, higher Bdnf mRNA levels were found in the HIT group (P < 0.001 vs. S and MIT groups). In the plantaris muscle, similar Bdnf mRNA levels were found in all groups. CONCLUSIONS: These results indicate that high-intensity chronic exercise reduces BDNF protein level in fast muscles and increases Bdnf mRNA levels in slow muscles.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Regulação da Expressão Gênica/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Condicionamento Físico Animal , Resistência Física/fisiologia , Análise de Variância , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar
19.
J Theor Biol ; 410: 77-106, 2016 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-27524647

RESUMO

Downstream connection effects on transcription are caused by retroactivity. When biomolecular dynamical systems interconnect retroactivity is a property that becomes important. The biological functional meaning of these effects is increasingly becoming an area of interest. Downstream targets, which are operator binding sites in transcriptional networks, may induce behaviors such as ultrasensitive responses or even represent an undesired issue in regulation. To the best of our knowledge, the role of the binding mechanisms of transcription factors in relation to minimizing - or enhancing - retroactivity effects has not been previously addressed. Our aim is to evaluate retroactivity effects considering how the binding mechanism impacts the number of free functional transcription factor (FFTF) molecules using a simple model via deterministic and stochastic simulations. We study four transcription factor binding mechanisms (BM): simple monomer binding (SMB), dimer binding (DB), cooperative sequential binding (CSB) and cooperative sequential binding with dimerization (CSB_D). We consider weak and strong binding regimes for each mechanism, where we contrast the cases when the FFTF is bound or unbound to the downstream loads. Upon interconnection, the number of FFTF molecules changed less for the SMB mechanism while for DB they changed the most. Our results show that for the chosen mechanisms (in terms of the corresponding described dynamics), retroactivity effects depend on transcription binding mechanisms. This contributes to the understanding of how the transcription factor regulatory function-such as decision making-and its dynamic needs for the response, may determine the nature of the selected binding mechanism.


Assuntos
Modelos Biológicos , Multimerização Proteica/fisiologia , Fatores de Transcrição/metabolismo , Transcrição Gênica/fisiologia , Animais , Humanos , Ligação Proteica/fisiologia , Processos Estocásticos , Fatores de Transcrição/química
20.
PLoS Comput Biol ; 11(6): e1004324, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26090929

RESUMO

CD4+ T cells orchestrate the adaptive immune response in vertebrates. While both experimental and modeling work has been conducted to understand the molecular genetic mechanisms involved in CD4+ T cell responses and fate attainment, the dynamic role of intrinsic (produced by CD4+ T lymphocytes) versus extrinsic (produced by other cells) components remains unclear, and the mechanistic and dynamic understanding of the plastic responses of these cells remains incomplete. In this work, we studied a regulatory network for the core transcription factors involved in CD4+ T cell-fate attainment. We first show that this core is not sufficient to recover common CD4+ T phenotypes. We thus postulate a minimal Boolean regulatory network model derived from a larger and more comprehensive network that is based on experimental data. The minimal network integrates transcriptional regulation, signaling pathways and the micro-environment. This network model recovers reported configurations of most of the characterized cell types (Th0, Th1, Th2, Th17, Tfh, Th9, iTreg, and Foxp3-independent T regulatory cells). This transcriptional-signaling regulatory network is robust and recovers mutant configurations that have been reported experimentally. Additionally, this model recovers many of the plasticity patterns documented for different T CD4+ cell types, as summarized in a cell-fate map. We tested the effects of various micro-environments and transient perturbations on such transitions among CD4+ T cell types. Interestingly, most cell-fate transitions were induced by transient activations, with the opposite behavior associated with transient inhibitions. Finally, we used a novel methodology was used to establish that T-bet, TGF-ß and suppressors of cytokine signaling proteins are keys to recovering observed CD4+ T cell plastic responses. In conclusion, the observed CD4+ T cell-types and transition patterns emerge from the feedback between the intrinsic or intracellular regulatory core and the micro-environment. We discuss the broader use of this approach for other plastic systems and possible therapeutic interventions.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular/imunologia , Plasticidade Celular/imunologia , Modelos Imunológicos , Transdução de Sinais/imunologia , Microambiente Celular , Biologia Computacional , Citocinas/metabolismo
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