RESUMEN
The coordinated movement of germ layer progenitor cells reaches its peak at the dorsal side, where the Bmp signaling gradient is low, and minimum at the ventral side, where the Bmp gradient is high. This dynamic cell movement is regulated by the interplay of various signaling pathways. The noncanonical Wnt signaling cascade serves as a pivotal regulator of convergence and extension cell movement, facilitated by the activation of small GTPases such as Rho, Rab, and Rac. However, the underlying cause of limited cell movement at the ventral side remains elusive. To explore the functional role of a key regulator in constraining gastrulation cell movement at the ventral side, we investigated the Bmp4-direct target gene, sizzled (szl), to assess its potential role in inhibiting noncanonical Wnt signaling. In our current study, we demonstrated that ectopic expression of szl led to gastrulation defects in a dose-dependent manner without altering cell fate specification. Overexpression of szl resulted in decreased elongation of Activin-treated animal cap and Keller explants. Furthermore, our immunoprecipitation assay unveiled the physical interaction of Szl with noncanonical Wnt ligand proteins (Wnt5 and Wnt11). Additionally, the activation of small GTPases involved in Wnt signaling mediation (RhoA and Rac1) was diminished upon szl overexpression. In summary, our findings suggest that Bmp4 signaling negatively modulates cell movement from the ventral side of the embryo by inducing szl expression during early Xenopus gastrulation.
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Proteína Morfogenética Ósea 4 , Movimiento Celular , Gastrulación , Proteínas de Xenopus , Xenopus laevis , Animales , Proteína Morfogenética Ósea 4/metabolismo , Ligandos , Proteínas Wnt/metabolismo , Vía de Señalización Wnt , Xenopus laevis/embriología , Xenopus laevis/metabolismo , Proteínas de Xenopus/metabolismo , Proteínas de Xenopus/genéticaRESUMEN
The Bmp/Smad1 pathway plays a crucial role in developmental processes and tissue homeostasis. Mitogen-activated protein kinase (Mapk)/Erk mediated phosphorylation of Smad1 in the linker region leads to Smad1 degradation, cytoplasmic retention and inhibition of Bmp/Smad1 signaling. While Fgf/Erk pathway has been documented to inhibit Bmp/Smad1 signaling, several studies also suggests the cooperative interaction between these two pathways in different context. However, the precise role and molecular pathway of this collaborative interaction remain obscure. Here, we identified Xbra induced by Fgf/Erk signaling as a factor in a protective mechanism for Smad1. Xbra physically interacted with the linker region phosphorylated Smad1 to make Xbra/Smad1/Smad4 trimeric complex, leading to Smad1 nuclear localization and protecting it from ubiquitin-mediated proteasomal degradation. This interaction of Xbra/Smad1/Smad4 led to sustained nuclear localization of Smad1 and the upregulation of lateral mesoderm genes, while concurrently suppression of neural and blood forming genes. Taken together, the results suggests Xbra-dependent cooperative interplays between Fgf/Erk and Bmp/Smad1 signaling during lateral mesoderm specification in Xenopus embryos.
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Proteínas Quinasas Activadas por Mitógenos , Transducción de Señal , Animales , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Sistema Nervioso/metabolismo , Fosforilación , Proteína Smad1/genética , Proteína Smad1/metabolismo , Xenopus laevis/metabolismo , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismoRESUMEN
Parkinson's disease (PD) is a complex neurodegenerative disorder with an unclear etiology. Despite significant research efforts, developing disease-modifying treatments for PD remains a major unmet medical need. Notably, drug repositioning is becoming an increasingly attractive direction in drug discovery, and computational approaches offer a relatively quick and resource-saving method for identifying testable hypotheses that promote drug repositioning. We used an artificial intelligence (AI)-based drug repositioning strategy to screen an extensive compound library and identify potential therapeutic agents for PD. Our AI-driven analysis revealed that efavirenz and nevirapine, approved for treating human immunodeficiency virus infection, had distinct profiles, suggesting their potential effects on PD pathophysiology. Among these, efavirenz attenuated α-synuclein (α-syn) propagation and associated neuroinflammation in the brain of preformed α-syn fibrils-injected A53T α-syn Tg mice and α-syn propagation and associated behavioral changes in the C. elegans BiFC model. Through in-depth molecular investigations, we found that efavirenz can modulate cholesterol metabolism and mitigate α-syn propagation, a key pathological feature implicated in PD progression by regulating CYP46A1. This study opens new avenues for further investigation into the mechanisms underlying PD pathology and the exploration of additional drug candidates using advanced computational methodologies.
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Alquinos , Inteligencia Artificial , Benzoxazinas , Ciclopropanos , Reposicionamiento de Medicamentos , Enfermedad de Parkinson , alfa-Sinucleína , Ciclopropanos/farmacología , Ciclopropanos/uso terapéutico , Alquinos/farmacología , Benzoxazinas/farmacología , Reposicionamiento de Medicamentos/métodos , Animales , alfa-Sinucleína/metabolismo , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , Ratones , Caenorhabditis elegans/efectos de los fármacos , Ratones Transgénicos , Humanos , Nevirapina/farmacología , Modelos Animales de Enfermedad , Ratones Endogámicos C57BLRESUMEN
A comprehensive regulatory network of transcription factors controls the dorsoventral patterning of the body axis in developing vertebrate embryos. Bone morphogenetic protein signaling is essential for activating the Ventx family of homeodomain transcription factors, which regulates embryonic patterning and germ layer identity during Xenopus gastrulation. Although Ventx1.1 and Ventx2.1 of the Xenopus Ventx family have been extensively investigated, Ventx3.2 remains largely understudied. Therefore, this study aimed to investigate the transcriptional regulation of ventx3.2 during the embryonic development of Xenopus. We used goosecoid (Gsc) genome-wide chromatin immunoprecipitation-sequencing data to isolate and replicate the promoter region of ventx3.2. Serial deletion and site-directed mutagenesis were used to identify the cis-acting elements for Gsc and caudal type homeobox 1 (Cdx1) within the ventx3.2 promoter. Cdx1 and Gsc differentially regulated ventx3.2 transcription in this study. Additionally, positive cis-acting and negative response elements were observed for Cdx1 and Gsc, respectively, within the 5' flanking region of the ventx3.2 promoter. This result was corroborated by mapping the active Cdx1 response element (CRE) and Gsc response element (GRE). Moreover, a point mutation within the CRE and GRE completely abolished the activator and repressive activities of Cdx1 and Gsc, respectively. Furthermore, the chromatin immunoprecipitation-polymerase chain reaction confirmed the direct binding of Cdx1 and Gsc to the CRE and GRE, respectively. Inhibition of Cdx1 and Gsc activities at their respective functional regions, namely, the ventral marginal zone and dorsal marginal zone, reversed their effects on ventx3.2 transcription. These results indicate that Cdx1 and Gsc modulate ventx3.2 transcription in the ventral marginal zone and dorsal marginal zone by directly binding to the promoter region during Xenopus gastrulation.
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Gástrula , Proteínas de Homeodominio , Regiones Promotoras Genéticas , Proteínas de Xenopus , Xenopus laevis , Animales , Proteína Morfogenética Ósea 4/metabolismo , Proteína Morfogenética Ósea 4/genética , Gástrula/metabolismo , Regulación del Desarrollo de la Expresión Génica , Proteína Goosecoide/genética , Proteína Goosecoide/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Regiones Promotoras Genéticas/genética , Unión Proteica , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Transcripción Genética , Xenopus laevis/genética , Xenopus laevis/metabolismo , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismoRESUMEN
BACKGROUND: Parkinson's disease (PD) is a common and costly progressive neurodegenerative disease of unclear etiology. A disease-modifying approach that can directly stop or slow its progression remains a major unmet need in the treatment of PD. A clinical pharmacology-based drug repositioning strategy is a useful approach for identifying new drugs for PD. METHODS: We analyzed claims data obtained from the National Health Insurance Service (NHIS), which covers a significant portion of the South Korean population, to investigate the association between antihistamines, a class of drugs commonly used to treat allergic symptoms by blocking H1 receptor, and PD in a real-world setting. Additionally, we validated this model using various animal models of PD such as the 6-hydroxydopmaine (6-OHDA), α-synuclein preformed fibrils (PFF) injection, and Caenorhabditis elegans (C. elegans) models. Finally, whole transcriptome data and Ingenuity Pathway Analysis (IPA) were used to elucidate drug mechanism pathways. RESULTS: We identified fexofenadine as the most promising candidate using National Health Insurance claims data in the real world. In several animal models, including the 6-OHDA, PFF injection, and C. elegans models, fexofenadine ameliorated PD-related pathologies. RNA-seq analysis and the subsequent experiments suggested that fexofenadine is effective in PD via inhibition of peripheral immune cell infiltration into the brain. CONCLUSION: Fexofenadine shows promise for the treatment of PD, identified through clinical data and validated in diverse animal models. This combined clinical and preclinical approach offers valuable insights for developing novel PD therapeutics.
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Enfermedades Neurodegenerativas , Enfermedad de Parkinson , Terfenadina/análogos & derivados , Animales , Enfermedad de Parkinson/patología , Caenorhabditis elegans/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Oxidopamina , Modelos Animales de Enfermedad , alfa-Sinucleína/metabolismo , Neuronas DopaminérgicasRESUMEN
A recent study revealed that the loss of Deup1 expression does not affect either centriole amplification or multicilia formation. Therefore, the deuterosome per se is not a platform for amplification of centrioles. In this study, we examine whether gain-of-function of Deup1 affects the development of multiciliated ependymal cells. Our time-lapse study reveals that deuterosomes with an average diameter of 300 nm have two different fates during ependymal differentiation. In the first instance, deuterosomes are scattered and gradually disappear as cells become multiciliated. In the second instance, deuterosomes self-organize into a larger aggregate, called a deuterosome cluster (DC). Unlike scattered deuterosomes, DCs possess centriole components primarily within their large structure. A characteristic of DC-containing cells is that they tend to become primary ciliated rather than multiciliated. Our in utero electroporation study shows that DCs in ependymal tissue are mostly observed at early postnatal stages, but are scarce at late postnatal stages, suggesting the presence of DC antagonists within the differentiating cells. Importantly, from our bead flow assay, ectopic expression of Deup1 significantly impairs cerebrospinal fluid flow. Furthermore, we show that expression of mouse Deup1 in Xenopus embryos has an inhibitory effect on differentiation of multiciliated cells in the epidermis. Taken together, we conclude that the DC formation of Deup1 in multiciliated cells inhibits production of multiple centrioles.
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Centriolos , Cilios , Animales , Ratones , Diferenciación Celular , Células Cultivadas , Centriolos/metabolismo , Cilios/metabolismo , Xenopus laevisRESUMEN
Viral myocarditis is an inflammatory disease of the myocardium, often leads to cardiac dysfunction and death. PARKIN (PRKN) and PINK1, well known as Parkinson's disease-associated genes, have been reported to be involved in innate immunity and mitochondrial damage control. Therefore, we investigated the role of parkin and PINK1 in coxsackievirus B3 (CVB3)-induced viral myocarditis because the etiology of myocarditis is related to abnormal immune response to viral infection and mitochondrial damage. After viral infection, the survival was significantly lower and myocardial damage was more severe in parkin knockout (KO) and PINK1 KO mice compared to wild-type (WT) mice. Parkin KO and PINK1 KO showed defective immune cell recruitment and impaired production of antiviral cytokines such as interferon-gamma, allowing increased viral replication. In addition, parkin KO and PINK1 KO mice were more susceptible to CVB3-induced mitochondrial damage than WT mice, resulting in susceptibility to viral-induced cardiac damage. Finally, using publicly available RNA-seq data, we found that pathogenic mutants of the PRKN gene are more common in patients with dilated cardiomyopathy and myocarditis than in controls or the general population. This study will help elucidate the molecular mechanism of CVB3-induced viral myocarditis.
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Infecciones por Coxsackievirus , Miocarditis , Virosis , Animales , Humanos , Ratones , Infecciones por Coxsackievirus/genética , Infecciones por Coxsackievirus/patología , Modelos Animales de Enfermedad , Enterovirus Humano B/genética , Ratones Noqueados , Miocarditis/genética , Miocarditis/patología , Proteínas Quinasas/genética , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Fibroblast growth factors (FGFs) encode a large family of growth factor proteins that activate several intracellular signaling pathways to control diverse physiological functions. The human genome encodes 22 FGFs that share a high sequence and structural homology with those of other vertebrates. FGFs orchestrate diverse biological functions by regulating cellular differentiation, proliferation, and migration. Dysregulated FGF signaling may contribute to several pathological conditions, including cancer. Notably, FGFs exhibit wide functional diversity among different vertebrates spatiotemporally. A comparative study of FGF receptor ligands and their diverse roles in vertebrates ranging from embryonic development to pathological conditions may expand our understanding of FGF. Moreover, targeting diverse FGF signals requires knowledge regarding their structural and functional heterogeneity among vertebrates. This study summarizes the current understanding of human FGF signals and correlates them with those in mouse and Xenopus models, thereby facilitating the identification of therapeutic targets for various human disorders.
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Factores de Crecimiento de Fibroblastos , Neoplasias , Humanos , Animales , Ratones , Xenopus laevis/metabolismo , Ligandos , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Receptores de Factores de Crecimiento de Fibroblastos/genética , Receptores de Factores de Crecimiento de Fibroblastos/metabolismo , Desarrollo Embrionario/genética , Neoplasias/genéticaRESUMEN
Cellular aging is the most severe risk factor for neurodegenerative disease. Simultaneously, oxidative stress (OS) is a critical factor in the aging process, resulting from an imbalance between reactive oxygen and nitrogen species and the antioxidant defense system. Emerging evidence indicates that OS is a common cause of several age-related brain pathologies, including cerebrovascular diseases. Elevated OS disrupts endothelial functional ability by diminishing the bioavailability of nitric oxide (a vascular dilator), induces atherosclerosis, and impairs vasculature, which are all common characteristics of cerebrovascular disease. In this review, we summarize evidence supporting an active role of OS in cerebrovascular disease progression, focusing primarily on stroke pathogenesis. We briefly discuss hypertension, diabetes, heart disease, and genetic factors that are often linked to OS and are considered associated factors influencing stroke pathology. Finally, we discuss the current pharmaceutics/therapeutics available for treating several cerebrovascular diseases.
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Trastornos Cerebrovasculares , Hipertensión , Enfermedades Neurodegenerativas , Accidente Cerebrovascular , Humanos , Estrés OxidativoRESUMEN
The reciprocal inhibition between two signaling centers, the Spemann organizer (dorsal mesoderm) and ventral region (mesoderm and ectoderm), collectively regulate the overall development of vertebrate embryos. Each center expresses key homeobox transcription factors (TFs) that directly control target gene transcription. Goosecoid (Gsc) is an organizer (dorsal mesoderm)-specific TF known to induce dorsal fate and inhibit ventral/ectodermal specification. Ventx1.1 (downstream of Bmp signaling) induces the epidermal lineage and inhibits dorsal organizer-specific genes from the ventral region. Chordin (Chrd) is an organizer-specific secreted Bmp antagonist whose expression is primarily activated by Gsc. Alternatively, chrd expression is repressed by Bmp/Ventx1.1 in the ventral/epidermal region. However, the regulatory mechanisms underlying the transcription mediated by Gsc and Ventx1.1 remain elusive. Here, we found that the chrd promoter contained two cis-acting response elements that responded negatively to Ventx1.1 and positively to Gsc. In the ventral/ectodermal region, Ventx1.1 was directly bound to the Ventx1.1 response element (VRE) and inhibited chrd transcription. In the organizer region, Gsc was bound to the Gsc response elements (GRE) to activate chrd transcription. The Gsc-mediated positive response on the chrd promoter completely depended on another adjacent Wnt response cis-acting element (WRE), which was the TCF7 (also known as Tcf1) binding element. Site-directed mutagenesis of VRE, GRE, or WRE completely abolished the repressive or activator activity of Ventx1.1 and Gsc, respectively. The ChIP-PCR results confirmed the direct binding of Ventx1.1 and Gsc/Tcf7 to VRE and GRE/WRE, respectively. These results demonstrated that chrd expression is oppositely modulated by homeobox TFs, Ventx1.1, and Gsc/Tcf7 during the embryonic patterning of Xenopus gastrula.
Asunto(s)
Gástrula , Glicoproteínas , Proteína Goosecoide , Factores de Transcripción , Proteínas de Xenopus , Xenopus laevis , Animales , Gástrula/metabolismo , Genes Homeobox , Proteína Goosecoide/genética , Proteína Goosecoide/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Xenopus laevis/embriología , Xenopus laevis/metabolismo , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismo , Glicoproteínas/metabolismoRESUMEN
To test whether homologous recombination repair (HRR) depends on FOXO3a, a cellular aging model of human dermal fibroblast (HDF) and tet-on flag-h-FOXO3a transgenic mice were studied. HDF cells transfected with over-expression of wt-h-FOXO3a increased the protein levels of MRE11, BRCA1, BRIP1, and RAD50, while knock-down with siFOXO3a decreased them. The protein levels of MRE11, BRCA1, BRIP1, RAD50, and RAD51 decreased during cellular aging. Chromatin immunoprecipitation (ChIP) assay was performed on FOXO3a binding accessibility to FOXO consensus sites in human MRE11, BRCA1, BRIP1, and RAD50 promoters; the results showed FOXO3a binding decreased during cellular aging. When the tet-on flag-h-FOXO3a mice were administered doxycycline orally, the protein and mRNA levels of flag-h-FOXO3a, MRE11, BRCA1, BRIP1, and RAD50 increased in a doxycycline-dose-dependent manner. In vitro HRR assays were performed by transfection with an HR vector and I-SceI vector. The mRNA levels of the recombined GFP increased after doxycycline treatment in MEF but not in wt-MEF, and increased in young HDF comparing to old HDF, indicating that FOXO3a activates HRR. Overall, these results demonstrate that MRE11, BRCA1, BRIP1, and RAD50 are transcriptional target genes for FOXO3a, and HRR activity is increased via transcriptional activation of MRE11, BRCA1, BRIP1, and RAD50 by FOXO3a.
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Reparación del ADN , Reparación del ADN por Recombinación , Humanos , Ratones , Animales , Activación Transcripcional , ADN Helicasas/genética , ARN Mensajero , Proteínas de Unión al ADN/genética , Ácido Anhídrido Hidrolasas/genética , Proteína BRCA1/genéticaRESUMEN
Sizzled (Szl) is a secreted frizzled protein, having a sequence homology with the extracellular cysteine-rich domain (CRD) of the Wnt receptor, 'Frizzled'. Contrary to the other secreted frizzled like proteins (Sfrps), szl belongs to the bone morphogenetic protein 4 (Bmp4) synexpression group and is tightly coexpressed with Bmp4. What is not known is how the szl transcription achieves its Bmp4 synexpression pattern. To address the molecular details of szl transcription control, we cloned a promoter of size 1566 base pairs for szl (bps) from the Xenopus laevis genomic DNA. Luciferase and eGFP reporter gene results of this szl promoter (-1566 bp) in its activation and repression patterns by Bmp4/Smad1 and a dominant negative Bmp4 receptor (DNBR) were similar to those of the endogenous szl expression. Reporter gene assays and site-directed mutagenesis of the szl promoter mapped an active Bmp4/Smad1 response element (BRE) and a cis-acting element, which competitively share a direct binding site for Ventx1.1 and Ventx2.1 (a Ventx response element, VRE). Smad1 and ventx2.1 alone increased szl promoter activity; in addition, the binding of each protein component was enhanced with their coexpression. Interestingly, Ventx1.1 repressed this reporter gene activity; however, Ventx1.1 and Ventx2.1 together positively regulated the szl promoter activity. From our analysis, Ventx2.1 binding was enhanced by Ventx1.1, but Ventx1.1 inhibitory binding was inhibited by co-injection of Ventx2.1 for the VRE site. The inhibitory Ventx1.1 co-injection decreased Smad1 binding on the szl promoter. In a triple combination of overexpressed Smad1/Ventx1.1/Ventx2.1, the reduced binding of Smad1 from Ventx1.1 was recovered to that of the Smad1/Ventx2 combination. Collectively, this study provides evidence of Bmp4/Smad1 signaling for a primary immediate early response and its two oppositely behaving target transcription factors, Ventx1.1 and Ventx2.1, for a secondary response, as they together upregulate the szl promoter's activity to achieve szl expression in a Bmp4 synexpression manner.
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Factores de Transcripción , Proteínas de Xenopus , Animales , Xenopus laevis/genética , Xenopus laevis/metabolismo , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismo , Factores de Transcripción/metabolismo , Regiones Promotoras Genéticas , Sitios de Unión , Proteína Morfogenética Ósea 4/genética , Proteína Morfogenética Ósea 4/metabolismo , Proteína Smad1/genética , Proteína Smad1/metabolismoRESUMEN
The presence of protein inclusions, called Lewy bodies (LBs) and Lewy neurites (LNs), in the brain is the main feature of Parkinson's disease (PD). Recent evidence that the prion-like propagation of α-synuclein (α-syn), as a major component of LBs and LNs, plays an important role in the progression of PD has gained much attention, although the molecular mechanism remains unclear. In this study, we evaluated whether neuronal ApoE regulates the cell-to-cell transmission of α-syn and explored its molecular mechanism using in vitro and in vivo model systems. We demonstrate that neuronal ApoE deficiency attenuates both α-syn uptake and release by downregulating LRP-1 and LDLR expression and enhancing chaperone-mediated autophagy activity, respectively, thereby contributing to α-syn propagation. In addition, we observed that α-syn propagation was attenuated in ApoE knockout mice injected with pre-formed mouse α-syn fibrils. This study will help our understanding of the molecular mechanisms underlying α-syn propagation.
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Apolipoproteínas E/metabolismo , Enfermedad de Parkinson , alfa-Sinucleína/metabolismo , Animales , Apolipoproteínas E/genética , Cuerpos de Lewy/metabolismo , Ratones , Neuronas/metabolismo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/metabolismo , alfa-Sinucleína/genéticaRESUMEN
In MYCN-amplified neuroblastoma (NB), we noticed that the single compound treatment with the HDAC inhibitor vorinostat led to a reprogramming of the glycolytic pathway in these cells. This reprogramming was upregulation of fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS), allowing the cells to generate ATP, albeit at a reduced rate. This behavior was dependent on reduced levels of MYCN and a corresponding increase in the levels of PPARD transcription factors. By integrating metabolic and functional studies in NB cells and mouse xenografts, we demonstrate a compensatory upregulation of FAO/OXPHOS metabolism that promotes resistance to HDAC inhibitors. From the additional compounds that could reverse this metabolic reprogramming, the mTORC1 inhibitor sirolimus was selected. Besides both a block of glycolysis and OXPHOS, the HDAC/mTORC1 inhibitor combination produced significantly higher levels of reactive oxygen species (ROS) in the treated cells and in xenograft tumor samples, also a consequence of increased glycolytic block. The lead compounds were also tested for changes in the message levels of the glycolytic enzymes and their pathway activity, and HK2 and GPI glycolytic enzymes were most affected at their RNA message level. This combination was seen with no overall toxicity in treated mice in terms of weight loss or liver/kidney function.
Asunto(s)
Inhibidores de Histona Desacetilasas , Neuroblastoma , Animales , Línea Celular Tumoral , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Proteína Proto-Oncogénica N-Myc/genética , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/genética , Neuroblastoma/metabolismoRESUMEN
The Ventx family is one of the subfamilies of the ANTP (antennapedia) superfamily and belongs to the NK-like (NKL) subclass. Ventx is a homeobox transcription factor and has a DNA-interacting domain that is evolutionarily conserved throughout vertebrates. It has been extensively studied in Xenopus, zebrafish, and humans. The Ventx family contains transcriptional repressors widely involved in embryonic development and tumorigenesis in vertebrates. Several studies have documented that the Ventx family inhibited dorsal mesodermal formation, neural induction, and head formation in Xenopus and zebrafish. Moreover, Ventx2.2 showed functional similarities to Nanog and Barx1, leading to pluripotency and neural-crest migration in vertebrates. Among them, Ventx protein is an orthologue of the Ventx family in humans. Studies have demonstrated that human Ventx was strongly associated with myeloid-cell differentiation and acute myeloid leukemia. The therapeutic potential of Ventx family inhibition in combating cancer progression in humans is discussed. Additionally, we briefly discuss genome evolution, gene duplication, pseudo-allotetraploidy, and the homeobox family in Xenopus.
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Proteínas de Homeodominio , Leucemia Mieloide Aguda , Animales , Desarrollo Embrionario/genética , Genes Homeobox , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Leucemia Mieloide Aguda/metabolismo , Proteína Homeótica Nanog/genética , Proteína Homeótica Nanog/metabolismo , Factores de Transcripción/metabolismo , Xenopus laevis/metabolismo , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
Germ layer specification and axis formation are crucial events in embryonic development. The Spemann organizer regulates the early developmental processes by multiple regulatory mechanisms. This review focuses on the responsive signaling in organizer formation and how the organizer orchestrates the germ layer specification in vertebrates. Accumulated evidence indicates that the organizer influences embryonic development by dual signaling. Two parallel processes, the migration of the organizer's cells, followed by the transcriptional activation/deactivation of target genes, and the diffusion of secreting molecules, collectively direct the early development. Finally, we take an in-depth look at active signaling that originates from the organizer and involves germ layer specification and patterning.
RESUMEN
Spemann organizer is a center of dorsal mesoderm and itself retains the mesoderm character, but it has a stimulatory role for neighboring ectoderm cells in becoming neuroectoderm in gastrula embryos. Goosecoid (Gsc) overexpression in ventral region promotes secondary axis formation including neural tissues, but the role of gsc in neural specification could be indirect. We examined the neural inhibitory and stimulatory roles of gsc in the same cell and neighboring cells contexts. In the animal cap explant system, Gsc overexpression inhibited expression of neural specific genes including foxd4l1.1, zic3, ncam, and neurod. Genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) and promoter analysis of early neural genes of foxd4l1.1 and zic3 were performed to show that the neural inhibitory mode of gsc was direct. Site-directed mutagenesis and serially deleted construct studies of foxd4l1.1 promoter revealed that Gsc directly binds within the foxd4l1.1 promoter to repress its expression. Conjugation assay of animal cap explants was also performed to demonstrate an indirect neural stimulatory role for gsc. The genes for secretory molecules, Chordin and Noggin, were up-regulated in gsc injected cells with the neural fate only achieved in gsc uninjected neighboring cells. These experiments suggested that gsc regulates neuroectoderm formation negatively when expressed in the same cell and positively in neighboring cells via soluble factors. One is a direct suppressive circuit of neural genes in gsc expressing mesoderm cells and the other is an indirect stimulatory circuit for neurogenesis in neighboring ectoderm cells via secreted BMP antagonizers.
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Proteína Goosecoide/metabolismo , Placa Neural/embriología , Proteínas de Xenopus/metabolismo , Xenopus laevis/embriología , AnimalesRESUMEN
Inhibition of the bone morphogenetic proteins (BMPs) is the primary step toward neuroectoderm formation in vertebrates. In this process, the Spemann organizer of the dorsal mesoderm plays a decisive role by secreting several extracellular BMP inhibitors such as Chordin (Chrd). Chrd physically interacts with BMP proteins and inhibits BMP signaling, which triggers the expression of neural-specific transcription factors (TFs), including Foxd4l1.1. Thus, Chrd induces in a BMP-inhibited manner and promotes neuroectoderm formation. However, the regulatory feedback mechanism of Foxd4l1.1 on mesodermal genes expression during germ-layer specification has not been fully elucidated. In this study, we investigated the regulatory mechanism of Foxd4l1.1 on chrd (a mesodermal gene). We demonstrate that Foxd4l1.1 inhibits chrd expression during neuroectoderm formation in two ways: First, Foxd4l1.1 directly binds to FRE (Foxd4l1.1 response elements) within the chrd promoter region to inhibit transcription. Second, Foxd4l1.1 physically interacts with Smad2 and Smad3, and this interaction blocks Smad2 and Smad3 binding to activin response elements (AREs) within the chrd promoter. Site-directed mutagenesis of FRE within the chrd(-2250) promoter completely abolished repressor activity of the Foxd4l1.1. RT-PCR and reporter gene assay results indicate that Foxd4l1.1 strongly inhibits mesoderm- and ectoderm-specific marker genes to maintain neural fate. Altogether, these results suggest that Foxd4l1.1 negatively regulates chrd transcription by dual mechanism. Thus, our study demonstrates the existence of precise reciprocal regulation of chrd transcription during neuroectoderm and mesoderm germ-layer specification in Xenopus embryos.