RESUMEN
The cyanobacterial circadian oscillator, consisting of KaiA, KaiB, and KaiC proteins, drives global rhythms of gene expression and compaction of the chromosome and regulates the timing of cell division and natural transformation. While the KaiABC posttranslational oscillator can be reconstituted in vitro, the Kai-based oscillator is subject to several layers of regulation in vivo. Specifically, the oscillator proteins undergo changes in their subcellular localization patterns, where KaiA and KaiC are diffuse throughout the cell during the day and localized as a focus at or near the pole of the cell at night. Here, we report that the CI domain of KaiC, when in a hexameric state, is sufficient to target KaiC to the pole. Moreover, increased ATPase activity of KaiC correlates with enhanced polar localization. We identified proteins associated with KaiC in either a localized or diffuse state. We found that loss of Rbp2, found to be associated with localized KaiC, results in decreased incidence of KaiC localization and long-period circadian phenotypes. Rbp2 is an RNA-binding protein, and it appears that RNA-binding activity of Rbp2 is required to execute clock functions. These findings uncover previously unrecognized roles for Rbp2 in regulating the circadian clock and suggest that the proper localization of KaiC is required for a fully functional clock in vivo.
Asunto(s)
Relojes Circadianos , Synechococcus , Relojes Circadianos/genética , Ritmo Circadiano/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Péptidos y Proteínas de Señalización del Ritmo Circadiano , Synechococcus/genética , FosforilaciónRESUMEN
Retinol-binding protein 2 (RBP2, also known as cellular retinol-binding protein 2 (CRBP2)) is a member of the fatty acid-binding protein family and has been extensively studied for its role in facilitating dietary vitamin A (retinol) uptake and metabolism within enterocytes of the small intestine. RBP2 is present in highest concentrations in the proximal small intestine where it constitutes approximately 0.1-0.5% of soluble protein. Recent reports have established that RBP2 binds monoacylglycerols (MAGs) with high affinity, including the canonical endocannabinoid 2-arachidonoylglycerol (2-AG). Crystallographic studies reveal that retinol, 2-AG, or other long-chain MAGs alternatively can bind in the retinol-binding pocket of RBP2. It also has been demonstrated recently that Rbp2-deficient mice are more susceptible to developing obesity and associated metabolic phenotypes when exposed to a high fat diet, or as they age when fed a conventional chow diet. When subjected to an oral fat challenge, the Rbp2-deficient mice release into the circulation significantly more, compared to littermate controls, of the intestinal hormone glucose-dependent insulinotropic polypeptide (GIP). These new findings regarding RBP2 structure and actions within the intestine are the focus of this review.
Asunto(s)
Retinoides , Vitamina A , Animales , Transporte Biológico , Dieta Alta en Grasa , Ratones , Monoglicéridos/metabolismo , Retinoides/metabolismo , Proteínas Celulares de Unión al Retinol/química , Proteínas Celulares de Unión al Retinol/genética , Proteínas Celulares de Unión al Retinol/metabolismo , Vitamina A/metabolismoRESUMEN
The identification of innovative gene biomarkers with clinical efficacy is warranted for the treatment of acute myocardial infarction (AMI). The current study sought to screen potential target genes in AMI via bioinformatic analysis and analyze their effects on cardiomyocyte apoptosis. The differentially expressed long non-coding RNAs (lncRNAs) of AMI were screened, and the downstream microRNAs (miRNAs) and mRNAs of lncRNA antisense for X-inactive-specific transcript (lncRNA TSIX) were predicted accordingly. The diagnostic relationship between the 12 differentially expressed lncRNAs and AMI was analyzed by receiver operating characteristic (ROC). Next, the expressions of 12 lncRNAs, including miR-34a-5p and retinol binding protein 2 (RBP2) were all detected. The targeting relationships of miR-34a-5p with lncRNA TSIX and RBP2 were verified. AMI model was established and treated with Ad-TSIX and/or agomiR-34a-5p to evaluate the cardiac function and cardiomyocyte apoptosis of AMI mice. LncRNA TSIX was identified as the most differentially expressed lncRNA in AMI. Our findings revealed that LncRNA TSIX could function as an AMI diagnostic marker. LncRNA TSIX could target miR-34a-5p and miR-34a-5p could target RBP2. Upregulation of lncRNA TSIX could ameliorate cardiac injury inflicted by AMI and mitigate cardiomyocyte apoptosis. Upregulation of miR-34a-5p reversed the effect of lncRNA TSIX overexpression to ameliorate cardiomyocyte apoptosis in AMI mice. Overall, the overexpression of lncRNA TSIX inhibits cardiomyocyte apoptosis by competing with RBP2 to bind to miR-34a-5p and promoting RBP2.
RESUMEN
BACKGROUND: Chronic myeloid leukemia (CML) is a malignant clonal proliferative disease. Once it progresses into the phase of blast crisis (CML-BP), the curative effect is poor, and the fatality rate is extremely high. Therefore, it is urgent to explore the molecular mechanisms of blast crisis and identify new therapeutic targets. METHODS: The expression levels of miR-181d, RBP2 and NF-κB p65 were assessed in 42 newly diagnosed CML-CP patients and 15 CML-BP patients. Quantitative real-time PCR, Western blots, and cell proliferation assay were used to characterize the changes induced by overexpression or inhibition of miR-181d, RBP2 or p65. Luciferase reporter assay and ChIP assay was conducted to establish functional association between miR-181d, RBP2 and p65. Inhibition of miR-181d expression and its consequences in tumor growth was demonstrated in vivo models. RESULTS: We found that miR-181d was overexpressed in CML-BP, which promoted leukemia cell proliferation. Histone demethylase RBP2 was identified as a direct target of miR-181d which downregulated RBP2 expression. Moreover, RBP2 inhibited transcriptional expression of NF-κB subunit, p65 by binding to its promoter and demethylating the tri/dimethylated H3K4 region in the p65 promoter locus. In turn, p65 directly bound to miR-181d promoter and upregulated its expression. Therefore, RBP2 inhibition resulting from miR-181d overexpression led to p65 upregulation which further forwarded miR-181d expression. This miR-181d/RBP2/p65 feedback regulation caused sustained NF-κB activation, which contributed to the development of CML-BP. CONCLUSIONS: Taken together, the miR-181d/RBP2/p65 feedback regulation promoted CML-BP and miR-181d may serve as a potential therapeutic target of CML-BP.
RESUMEN
Present in the small intestine, cellular retinol binding protein 2 (CRBP2) plays an important role in the uptake, transport, and metabolism of dietary retinoids. However, the recent discovery of the interactions of CRBP2 with 2-arachidonoylglycerol and other monoacylglycerols (MAGs) suggests the broader involvement of this protein in lipid metabolism and signaling. To better understand the physiological role of CRBP2, we determined its protein-lipid interactome using a fluorescence-based retinol replacement assay adapted for a high-throughput screening format. By examining chemical libraries of bioactive lipids, we provided evidence for the selective interaction of CRBP2 with a subset of nonretinoid ligands with the highest affinity for sn-1 and sn-2 MAGs that contain polyunsaturated C18-C20 acyl chains. We also elucidated the structure-affinity relationship for nonretinoid ligands of this protein. We further dissect the molecular basis for this ligand's specificity by analyzing high-resolution crystal structures of CRBP2 in complex with selected derivatives of MAGs. Finally, we identify T51 and V62 as key amino acids that enable the broadening of ligand selectivity to MAGs in CRBP2 as compared with retinoid-specific CRBP1. Thus, our study provides the molecular framework for understanding the lipid selectivity and diverse functions of CRBPs in controlling lipid homeostasis.
Asunto(s)
Proteínas Celulares de Unión al RetinolRESUMEN
PURPOSE: The retinoblastoma binding protein RBP2 (KDM5A) is a histone demethylase that promotes cell growth in many human cancers. A series of functional experiments were conducted to explore the role of miR-421/KDM5A in ovarian cancer cells and their underlying molecular mechanisms. MATERIALS AND METHODS: Public microarray databases were analyzed to assess KDM5A and miR-421 expression in ovarian cancer. KDM5A was predicted to be a target of miR-421 using software analysis. The expression of the miR-421/KDM5A regulatory axis in ovarian cancer and the mechanisms of its effects on proliferation, migration, and invasion of ovarian cancer cell lines were investigated. RESULTS: Compared with normal ovarian tissues, the expression of KDM5A mRNA and protein was elevated (P<0.05), and miR-421 expression was reduced in ovarian cancer tissue (P<0.05). miR-421 was found to bind specifically to the KDM5A gene. Silencing KDM5A or overexpressing miR-421 significantly inhibited proliferation, migration, and invasion of OVCAR-8 and SKOV-3 cells. Similarly, compared with nude mice injected with cells transfected with empty capsids, the in vivo proliferation rate of OVCAR-8 cells after miR-421 overexpression was reduced significantly. CONCLUSION: The miR-421/KDM5A regulatory axis plays an important role in the development and progression of ovarian cancer cells.
RESUMEN
Rare genetic variants in LDLR, APOB and PCSK9 are known causes of familial hypercholesterolaemia and it is expected that rare variants in other genes will also have effects on hyperlipidaemia risk although such genes remain to be identified. The UK Biobank consists of a sample of 500,000 volunteers and exome sequence data is available for 50,000 of them. 11,490 of these were classified as hyperlipidaemia cases on the basis of having a relevant diagnosis recorded and/or taking lipid-lowering medication while the remaining 38,463 were treated as controls. Variants in each gene were assigned weights according to rarity and predicted impact and overall weighted burden scores were compared between cases and controls, including population principal components as covariates. One biologically plausible gene, HUWE1, produced statistically significant evidence for association after correction for testing 22,028 genes with a signed log10 p value (SLP) of -6.15, suggesting a protective effect of variants in this gene. Other genes with uncorrected p < .001 are arguably also of interest, including LDLR (SLP = 3.67), RBP2 (SLP = 3.14), NPFFR1 (SLP = 3.02) and ACOT9 (SLP = -3.19). Gene set analysis indicated that rare variants in genes involved in metabolism and energy can influence hyperlipidaemia risk. Overall, the results provide some leads which might be followed up with functional studies and which could be tested in additional data sets as these become available. This research has been conducted using the UK Biobank Resource.
Asunto(s)
Hiperlipidemias/genética , Hiperlipoproteinemia Tipo II/genética , Proproteína Convertasa 9/genética , Receptores de LDL/genética , Proteínas Supresoras de Tumor/genética , Ubiquitina-Proteína Ligasas/genética , Apolipoproteína B-100/genética , Bancos de Muestras Biológicas , LDL-Colesterol/genética , Exoma/genética , Femenino , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Humanos , Hiperlipidemias/patología , Hiperlipoproteinemia Tipo II/diagnóstico , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple/genética , Proteínas Celulares de Unión al Retinol/genética , Factores de Riesgo , Reino Unido , Secuenciación del ExomaRESUMEN
More than 90% of small cell lung cancers (SCLCs) harbor loss-of-function mutations in the tumor suppressor gene RB1 The canonical function of the RB1 gene product, pRB, is to repress the E2F transcription factor family, but pRB also functions to regulate cellular differentiation in part through its binding to the histone demethylase KDM5A (also known as RBP2 or JARID1A). We show that KDM5A promotes SCLC proliferation and SCLC's neuroendocrine differentiation phenotype in part by sustaining expression of the neuroendocrine transcription factor ASCL1. Mechanistically, we found that KDM5A sustains ASCL1 levels and neuroendocrine differentiation by repressing NOTCH2 and NOTCH target genes. To test the role of KDM5A in SCLC tumorigenesis in vivo, we developed a CRISPR/Cas9-based mouse model of SCLC by delivering an adenovirus (or an adeno-associated virus [AAV]) that expresses Cre recombinase and sgRNAs targeting Rb1, Tp53, and Rbl2 into the lungs of Lox-Stop-Lox Cas9 mice. Coinclusion of a KDM5A sgRNA decreased SCLC tumorigenesis and metastasis, and the SCLCs that formed despite the absence of KDM5A had higher NOTCH activity compared to KDM5A+/+ SCLCs. This work establishes a role for KDM5A in SCLC tumorigenesis and suggests that KDM5 inhibitors should be explored as treatments for SCLC.
Asunto(s)
Diferenciación Celular/genética , Células Neuroendocrinas/citología , Receptores Notch/fisiología , Proteína 2 de Unión a Retinoblastoma/metabolismo , Transducción de Señal/genética , Carcinoma Pulmonar de Células Pequeñas/enzimología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Línea Celular , Transformación Celular Neoplásica/genética , Modelos Animales de Enfermedad , Regulación Neoplásica de la Expresión Génica/genética , Histona Demetilasas/metabolismo , Humanos , Técnicas In Vitro , Ratones , Células Neuroendocrinas/patología , Carcinoma Pulmonar de Células Pequeñas/fisiopatologíaRESUMEN
Epigenetic disorders play a key role in tumorigenesis and development, among which histone methylation abnormalities are common. While patients living with chronic myeloid leukemia in the chronic phase (CML-CP) have a good response to TKI, blastic phase (CML-BP) patients demonstrate poor efficacy and high fatality rates. However, while the mechanism of blast crisis of chronic myeloid leukemia remains unclear, high expression and activation of BCR-ABL are usually related to CML blast crisis transition. We found that histone H3 lysine 4 (H3K4) demethylase RBP2 expression is negatively correlated with BCR-ABL expression, which suggests a regulatory link between these two genes. We also discovered that RBP2 mediates the dephosphorylation of BCR-ABL by directly downregulating PTEN expression, depending on histone demethylase activity, while PTEN targets protein phosphatase activity of BCR-ABL, a phosphatase which directly dephosphorylates BCR-ABL. In clinical specimens, the mRNA expression of RBP2 was found to be positively correlated with that of PTEN. These data suggest that the under-expression of RBP2 promotes blast crisis transition by activating an RBP2/PTEN/BCR-ABL cascade.
Asunto(s)
Crisis Blástica/metabolismo , Proteínas de Fusión bcr-abl/metabolismo , Fosfohidrolasa PTEN/metabolismo , Proteína 2 de Unión a Retinoblastoma/fisiología , Adulto , Anciano , Femenino , Células HEK293 , Humanos , Células K562 , Masculino , Persona de Mediana EdadRESUMEN
BACKGROUND: Histone demethylase JARID1B plays several context dependent roles in epigenetic regulation of cellular differentiation in normal development and is highly expressed in multiple human cancers. The protein is a strong transcriptional repressor capable of downregulating numerous genes. There are three splicing isoforms of JARID1B, however the links between the protein structure and function are not clear. The expression pattern of JARID1B in human melanoma seems to be different from observed in other cancers. Moreover, up to now no data on the impact of JARID1B expression in cutaneous melanoma on the patients' prognosis have been reported. METHODS: We investigated immunohistochemically the association of intratumoral expression of total JARID1B protein and its RBP2-H1 isoform in primary and metastatic melanomas with prognosis for the patients. RESULTS: Expression of both total JARID1B protein and its RBP2-H1 variant was found in all the melanomas investigated. Our results indicate, however, that only high (above 90% of the cells) intratumoral expression of RBP2-H1 can be considered prognostic factor associated with worse overall survival of the patients. CONCLUSIONS: Such results if considered together with data demonstrating a switch to enhanced expression of RBP2-H1 at early stages of malignant transformation of melanocytes are in agreement with hypothetical crucial role of JARID1B in the course of melanoma development and progression and suggest that altered splicing of JARID1B may be important factor increasing melanoma aggressiveness.
Asunto(s)
Empalme Alternativo/genética , Biomarcadores de Tumor/genética , Histona Demetilasas con Dominio de Jumonji/genética , Melanoma/genética , Proteínas Nucleares/genética , Proteínas Represoras/genética , Neoplasias Cutáneas/genética , Biomarcadores de Tumor/metabolismo , Progresión de la Enfermedad , Epigénesis Genética/genética , Regulación Neoplásica de la Expresión Génica , Humanos , Inmunohistoquímica , Histona Demetilasas con Dominio de Jumonji/metabolismo , Estimación de Kaplan-Meier , Metástasis Linfática , Melanoma/mortalidad , Melanoma/patología , Melanoma/cirugía , Proteínas Nucleares/metabolismo , Pronóstico , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Represoras/metabolismo , Neoplasias Cutáneas/mortalidad , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/cirugíaRESUMEN
Eukaryotic chromosome segregation requires a protein complex known as the kinetochore that mediates attachment between mitotic spindle microtubules and centromere-specific nucleosomes composed of the widely conserved histone variant CENP-A. Mutations in kinetochore proteins of the fission yeast Schizosaccharomyces pombe lead to chromosome missegregation such that daughter cells emerge from mitosis with unequal DNA content. We find that multiple copies of Msc1-a fission yeast homolog of the KDM5 family of proteins-suppresses the temperature-sensitive growth defect of several kinetochore mutants, including mis16 and mis18, as well as mis6, mis15, and mis17, components of the Constitutive Centromere Associated Network (CCAN). On the other hand, deletion of msc1 exacerbates both the growth defect and chromosome missegregation phenotype of each of these mutants. The C-terminal PHD domains of Msc1, previously shown to associate with a histone deacetylase activity, are necessary for Msc1 function when kinetochore mutants are compromised. We also demonstrate that, in the absence of Msc1, the frequency of localization to the kinetochore of Mis16 and Mis15 is altered from wild-type cells. As we show here for msc1, others have shown that elevating cnp1 levels acts similarly to promote survival of the CCAN mutants. The rescue of mis15 and mis17 by cnp1 is, however, independent of msc1 Thus, Msc1 appears to contribute to the chromatin environment at the centromere: the absence of Msc1 sensitizes cells to perturbations in kinetochore function, while elevating Msc1 overcomes loss of function of critical components of the kinetochore and centromere.
Asunto(s)
Cromatina/genética , Proteínas de Unión al ADN/metabolismo , Cinetocoros/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Centrómero/genética , Centrómero/metabolismo , Cromatina/metabolismo , Ensamble y Desensamble de Cromatina , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Segregación Cromosómica , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Dominios Proteicos , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/genéticaRESUMEN
Malaria in humans is caused by six species of Plasmodium parasites, of which the nuclear genome sequences for the two Plasmodium ovale spp., P. ovale curtisi and P. ovale wallikeri, and Plasmodium malariae have not yet been analyzed. Here we present an analysis of the nuclear genome sequences of these three parasites, and describe gene family expansions therein. Plasmodium ovale curtisi and P. ovale wallikeri are genetically distinct but morphologically indistinguishable and have sympatric ranges through the tropics of Africa, Asia and Oceania. Both P. ovale spp. show expansion of the surfin variant gene family, and an amplification of the Plasmodium interspersed repeat (pir) superfamily which results in an approximately 30% increase in genome size. For comparison, we have also analyzed the draft nuclear genome of P. malariae, a malaria parasite causing mild malaria symptoms with a quartan life cycle, long-term chronic infections, and wide geographic distribution. Plasmodium malariae shows only a moderate level of expansion of pir genes, and unique expansions of a highly diverged transmembrane protein family with over 550 members and the gamete P25/27 gene family. The observed diversity in the P. ovale wallikeri and P. ovale curtisi surface antigens, combined with their phylogenetic separation, supports consideration that the two parasites be given species status.
Asunto(s)
Genoma de Protozoos , Familia de Multigenes , Plasmodium malariae/genética , Plasmodium ovale/genética , Adulto , África Occidental , Animales , Antígenos de Protozoos/genética , Antígenos de Superficie/genética , China , Homólogo de la Proteína Chromobox 5 , Variación Genética , Humanos , Secuencias Repetitivas Esparcidas/genética , Masculino , Proteínas de la Membrana/genética , Familia de Multigenes/genética , Filogenia , Plasmodium falciparum/clasificación , Plasmodium falciparum/genética , Plasmodium knowlesi/clasificación , Plasmodium knowlesi/genética , Plasmodium malariae/clasificación , Plasmodium ovale/clasificación , Plasmodium vivax/clasificación , Plasmodium vivax/genética , Adulto JovenRESUMEN
Accurate chromosome segregation is necessary to ensure genomic integrity. Segregation depends on the proper functioning of the centromere, kinetochore, and mitotic spindle microtubules and is monitored by the spindle assembly checkpoint (SAC). In the fission yeast Schizosaccharomyces pombe, defects in Dis1, a microtubule-associated protein that influences microtubule dynamics, lead to mitotic arrest as a result of an active SAC and consequent failure to grow at low temperature. In a mutant dis1 background (dis1-288), loss of function of Msc1, a fission yeast homolog of the KDM5 family of proteins, suppresses the growth defect and promotes normal mitosis. Genetic analysis implicates a histone deacetylase (HDAC)-linked pathway in suppression because HDAC mutants clr6-1, clr3∆, and sir2∆, though not hos2∆, also promote normal mitosis in the dis1-288 mutant. Suppression of the dis phenotype through loss of msc1 function requires the spindle checkpoint protein Mad2 and is limited by the presence of the heterochromatin-associated HP1 protein homolog Swi6. We speculate that alterations in histone acetylation promote a centromeric chromatin environment that compensates for compromised dis1 function by allowing for successful kinetochore-microtubule interactions that can satisfy the SAC. In cells arrested in mitosis by mutation of dis1, loss of function of epigenetic determinants such as Msc1 or specific HDACs can promote cell survival. Because the KDM5 family of proteins has been implicated in human cancers, an appreciation of the potential role of this family of proteins in chromosome segregation is warranted.
Asunto(s)
Centrómero , Cromatina/fisiología , Epigénesis Genética , Microtúbulos/fisiología , Mitosis , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/fisiología , Mutación , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/fisiologíaRESUMEN
The retinoblastoma tumor suppressor protein pRb restricts cell growth through inhibition of cell cycle progression. Increasing evidence suggests that pRb also promotes differentiation, but the mechanisms are poorly understood, and the key question remains as to how differentiation in tumor cells can be enhanced in order to diminish their aggressive potential. Previously, we identified the histone demethylase KDM5A (lysine [K]-specific demethylase 5A), which demethylates histone H3 on Lys4 (H3K4), as a pRB-interacting protein counteracting pRB's role in promoting differentiation. Here we show that loss of Kdm5a restores differentiation through increasing mitochondrial respiration. This metabolic effect is both necessary and sufficient to induce the expression of a network of cell type-specific signaling and structural genes. Importantly, the regulatory functions of pRB in the cell cycle and differentiation are distinct because although restoring differentiation requires intact mitochondrial function, it does not necessitate cell cycle exit. Cells lacking Rb1 exhibit defective mitochondria and decreased oxygen consumption. Kdm5a is a direct repressor of metabolic regulatory genes, thus explaining the compensatory role of Kdm5a deletion in restoring mitochondrial function and differentiation. Significantly, activation of mitochondrial function by the mitochondrial biogenesis regulator Pgc-1α (peroxisome proliferator-activated receptor γ-coactivator 1α; also called PPARGC1A) a coactivator of the Kdm5a target genes, is sufficient to override the differentiation block. Overexpression of Pgc-1α, like KDM5A deletion, inhibits cell growth in RB-negative human cancer cell lines. The rescue of differentiation by loss of KDM5A or by activation of mitochondrial biogenesis reveals the switch to oxidative phosphorylation as an essential step in restoring differentiation and a less aggressive cancer phenotype.
Asunto(s)
Diferenciación Celular/genética , Regulación del Desarrollo de la Expresión Génica/genética , Mitocondrias/enzimología , Mitocondrias/genética , Proteína de Retinoblastoma/genética , Proteína 2 de Unión a Retinoblastoma/metabolismo , Animales , Ciclo Celular , Línea Celular Tumoral , Células Cultivadas , Femenino , Fibroblastos/citología , Fibroblastos/enzimología , Humanos , Ratones , Proteínas Mitocondriales/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Proteína de Retinoblastoma/metabolismo , Proteína 2 de Unión a Retinoblastoma/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Some feedback pathways are critical in the process of tumor development or malignant progression. However the mechanisms through which these pathways are epigenetically regulated have not been fully elucidated. Here, we demonstrated that the histone demethylase RBP2 was crucial for TGF-ß1-(p-Smad3)-RBP2-E-cadherin-Smad3 feedback circuit that was implicated in malignant progression of tumors and its knockdown significantly inhibited gastric cancer (GC) metastasis both in vitro and in vivo. Mechanistically, RBP2 can directly bind to E-cadherin promoter and suppress its expression, facilitating EMT and distant metastasis of GC. RBP2 can also be induced by TGF-ß1, a key inducer of EMT, through phosphorylated Smad3 (p-Smad3) pathway in GC. The upregulated RBP2 can be recruited by p-smad3 to E-cadherin promoter and enhance its suppression, contributing to the promotion of metastasis of GC. In addition, the suppression of E-cadherin by RBP2 attenuated inhibition of Smad3 phosphorylation (exerted by E-cadherin), resulting further induction of RBP2 expression, and thus constituting positive feedback regulation during GC malignant progression. This TGF-ß1-(p-Smad3)-RBP2-E-cadherin-Smad3 feedback circuit may be a novel mechanism for GC malignant progression and suppression of RBP2 expression may serve as a new strategy for the prevention of tumor distant metastasis.
Asunto(s)
Proteínas Celulares de Unión al Retinol/metabolismo , Transducción de Señal/fisiología , Neoplasias Gástricas/patología , Animales , Cadherinas/metabolismo , Progresión de la Enfermedad , Transición Epitelial-Mesenquimal/fisiología , Retroalimentación Fisiológica/fisiología , Femenino , Técnicas de Silenciamiento del Gen , Xenoinjertos , Humanos , Masculino , Ratones , Ratones Desnudos , Fosforilación , Proteína smad3/metabolismo , Neoplasias Gástricas/metabolismo , Factor de Crecimiento Transformador beta1/metabolismoRESUMEN
Liver cirrhosis is one of the most common diseases of Chinese patients. Herein, we report the high expression of a newly identified histone 3 lysine 4 demethylase, retinoblastoma binding protein 2 (RBP2), and its role in liver cirrhosis in humans. The siRNA knockdown of RBP2 expression in hepatic stellate cells (HSCs) reduced levels of α-smooth muscle actin (α-SMA) and vimentin and decreased the proliferation of HSCs; and overexpression of RBP2 increased α-SMA and vimentin levels. Treatment with transforming growth factor β (TGF-β) upregulated the expression of RBP2, α-SMA, and vimentin, and the siRNA knockdown of RBP2 expression attenuated TGF-β-mediated upregulation of α-SMA and vimentin expression and HSC proliferation. Furthermore, RBP2 was highly expressed in cirrhotic rat livers. Therefore, RBP2 may participate in the pathogenesis of liver cirrhosis by regulating the expression of α-SMA and vimentin. RBP2 may be a useful marker for the diagnosis and treatment of liver cirrhosis.
Asunto(s)
Animales , Humanos , Masculino , Actinas/metabolismo , Células Estrelladas Hepáticas/metabolismo , Histona Demetilasas/metabolismo , Cirrosis Hepática/metabolismo , /metabolismo , Vimentina/metabolismo , Western Blotting , Proliferación Celular , Modelos Animales de Enfermedad , Expresión Génica , Técnicas de Silenciamiento del Gen , Ratas Wistar , ARN Interferente Pequeño/metabolismo , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Retinoblastoma binding protein 2 (RBP2), a newly found histone demethylase, is overexpressed in gastric cancer. We examined the upstream regulatory mechanism of RBP2 at the microRNA (miRNA) level and the role in gastric carcinogenesis. We used bioinformatics to predict that microRNA-212 (miR-212) might be a direct upstream regulator of RBP2 and verified the regulation in gastric epithelial-derived cell lines. Overexpression of miR-212 significantly inhibited the expression levels of RBP2, whereas knockdown of miR-212 promoted RBP2 expression. Furthermore, we identified the putative miR-212 targeting sequence in the RBP2 3' UTR by luciferase assay. MiR-212 inhibited the colony formation ability of cells by repressing RBP2 expression and increasing that of P21(CIP1) and P27(kip1), both critical in cell cycle arrest. In addition, the expression of RBP2 and miR-212 in tumor tissue and matched normal tissue from 18 patients further supported the results in vivo. MiR-212 directly regulates the expression of RBP2 and inhibits cell growth in gastric cancer, which may provide new clues to treatment.