RESUMO
The ability to switch between different lifestyles allows bacterial pathogens to thrive in diverse ecological niches1,2. However, a molecular understanding of their lifestyle changes within the human host is lacking. Here, by directly examining bacterial gene expression in human-derived samples, we discover a gene that orchestrates the transition between chronic and acute infection in the opportunistic pathogen Pseudomonas aeruginosa. The expression level of this gene, here named sicX, is the highest of the P. aeruginosa genes expressed in human chronic wound and cystic fibrosis infections, but it is expressed at extremely low levels during standard laboratory growth. We show that sicX encodes a small RNA that is strongly induced by low-oxygen conditions and post-transcriptionally regulates anaerobic ubiquinone biosynthesis. Deletion of sicX causes P. aeruginosa to switch from a chronic to an acute lifestyle in multiple mammalian models of infection. Notably, sicX is also a biomarker for this chronic-to-acute transition, as it is the most downregulated gene when a chronic infection is dispersed to cause acute septicaemia. This work solves a decades-old question regarding the molecular basis underlying the chronic-to-acute switch in P. aeruginosa and suggests oxygen as a primary environmental driver of acute lethality.
Assuntos
Doença Aguda , Doença Crônica , Genes Bacterianos , Oxigênio , Infecções por Pseudomonas , Pseudomonas aeruginosa , RNA Bacteriano , Animais , Humanos , Oxigênio/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/patogenicidade , Infecções por Pseudomonas/complicações , Infecções por Pseudomonas/microbiologia , Infecções por Pseudomonas/patologia , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , Fibrose Cística/microbiologia , Ferimentos e Lesões/microbiologia , Ubiquinona/biossíntese , Anaerobiose , Genes Bacterianos/genética , Sepse/complicações , Sepse/microbiologiaRESUMO
Histone chaperone FACT (facilitates chromatin transcription) is well known to promote chromatin recovery during transcription. However, the mechanism how FACT regulates genome-wide chromatin accessibility and transcription factor binding has not been fully elucidated. Through loss-of-function studies, we show here that FACT component Ssrp1 is required for DNA replication and DNA damage repair and is also essential for progression of cell phase transition and cell proliferation in mouse embryonic fibroblast cells. On the molecular level, absence of the Ssrp1 leads to increased chromatin accessibility, enhanced CTCF binding, and a remarkable change in dynamic range of gene expression. Our study thus unequivocally uncovers a unique mechanism by which FACT complex regulates transcription by coordinating genome-wide chromatin accessibility and CTCF binding.
Assuntos
Fator de Ligação a CCCTC , Cromatina , Proteínas de Ligação a DNA , Regulação da Expressão Gênica , Proteínas de Grupo de Alta Mobilidade , Chaperonas de Histonas , Animais , Camundongos , Fator de Ligação a CCCTC/genética , Fator de Ligação a CCCTC/metabolismo , Cromatina/genética , Replicação do DNA , Chaperonas de Histonas/genética , Proteínas de Ligação a DNA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Células NIH 3T3 , Reparo do DNARESUMO
Polycystic ovary syndrome (PCOS) is a highly heterogeneous and genetically complex endocrine disorder. Although the etiology remains mostly elusive, growing evidence suggests that abnormal changes of DNA methylation correlate well with systemic and tissue-specific dysfunctions in PCOS. Herein, a dehydroepiandrosterone-induced PCOS-like mouse model which has a similar metabolic and reproductive phenotype as human patients with PCOS was generated. It was used to experimentally validate the potential role of aberrant DNA methylation in PCOS in this study. Integrated DNA methylation and transcriptome analysis revealed the potential role of genomic DNA hypomethylation in transcription regulation of PCOS and identified several key candidate genes, including BMP4, Adcy7, Tnfaip3, and Fas, which were regulated by aberrant DNA hypomethylation. Moreover, i.p. injection of S-adenosylmethionine increased the overall DNA methylation level of PCOS-like mice and restored expression of the candidate genes to similar levels as the control, alleviating reproductive and metabolic abnormalities in PCOS-like mice. These findings provide direct evidence showing the importance of normal DNA methylation in epigenetic regulation of PCOS and potential targets for diagnosis and treatment of the disease.
Assuntos
Metilação de DNA , Síndrome do Ovário Policístico , Síndrome do Ovário Policístico/genética , Síndrome do Ovário Policístico/metabolismo , Síndrome do Ovário Policístico/patologia , Metilação de DNA/genética , Animais , Feminino , Camundongos , Modelos Animais de Doenças , Transcrição Gênica , Epigênese Genética , Regulação da Expressão Gênica , Humanos , Camundongos Endogâmicos C57BLRESUMO
A hallmark of microbial ecology is that interactions between members of a community shape community function. This includes microbial communities in human infections, such as chronic wounds, where interactions can result in more severe diseases. Staphylococcus aureus is the most common organism isolated from human chronic wound infections and has been shown to have both cooperative and competitive interactions with Pseudomonas aeruginosa. Still, despite considerable study, most interactions between these microbes have been characterized using in vitro well-mixed systems, which do not recapitulate the infection environment. Here, we characterized interactions between S. aureus and P. aeruginosa in chronic murine wounds, focusing on the role that both macro- and micro-scale spatial structures play in disease. We discovered that S. aureus and P. aeruginosa coexist at high cell densities in murine wounds. High-resolution imaging revealed that these microbes establish a patchy distribution, only occupying 5 to 25% of the wound volume. Using a quantitative framework, we identified a precise spatial structure at both the macro (mm)- and micro (µm)-scales, which was largely mediated by P. aeruginosa production of the antimicrobial 2-heptyl-4-hydroxyquinoline N-oxide, while the antimicrobial pyocyanin had no impact. Finally, we discovered that this precise spatial structure enhances S. aureus tolerance to aminoglycoside antibiotics but not vancomycin. Our results provide mechanistic insights into the biogeography of S. aureus and P. aeruginosa coinfected wounds and implicate spatial structure as a key determinant of antimicrobial tolerance in wound infections.
Assuntos
Coinfecção , Staphylococcus aureus Resistente à Meticilina , Infecções por Pseudomonas , Infecções Estafilocócicas , Infecção dos Ferimentos , Humanos , Camundongos , Animais , Staphylococcus aureus , Pseudomonas aeruginosa , Infecção dos Ferimentos/tratamento farmacológico , Infecções Estafilocócicas/tratamento farmacológico , Antibacterianos/farmacologia , Infecções por Pseudomonas/tratamento farmacológico , BiofilmesRESUMO
BACKGROUND: The global cellular landscape of the tumor microenvironment (TME) combining primary and metastatic liver tumors has not been comprehensively characterized. METHODS: Based on the scRNA-seq and spatial transcriptomic data of non-tumor liver tissues (NTs), primary liver tumors (PTs) and metastatic liver tumors (MTs), we performed the tissue preference, trajectory reconstruction, transcription factor activity inference, cell-cell interaction and cellular deconvolution analyses to construct a comprehensive cellular landscape of liver tumors. RESULTS: Our analyses depicted the heterogeneous cellular ecosystems in NTs, PTs and MTs. The activated memory B cells and effector T cells were shown to gradually shift to inhibitory B cells, regulatory or exhausted T cells in liver tumors, especially in MTs. Among them, we characterized a unique group of TCF7+ CD8+ memory T cells specifically enriched in MTs that could differentiate into exhausted T cells likely driven by the p38 MAPK signaling. With regard to myeloid cells, the liver-resident macrophages and inflammatory monocyte/macrophages were markedly replaced by tumor-associated macrophages (TAMs), with TREM2+ and UBE2C+ TAMs enriched in PTs, while SPP1+ and WDR45B+ TAMs in MTs. We further showed that the newly identified WDR45B+ TAMs exhibit an M2-like polarization and are associated with adverse prognosis in patients with liver metastases. Additionally, we addressed that endothelial cells display higher immune tolerance and angiogenesis capacity, and provided evidence for the source of the mesenchymal transformation of fibroblasts in tumors. Finally, the malignant hepatocytes and fibroblasts were prioritized as the pivotal cell populations in shaping the microenvironments of PTs and MTs, respectively. Notably, validation analyses by using spatial or bulk transcriptomic data in clinical cohorts concordantly emphasized the clinical significance of these findings. CONCLUSIONS: This study defines the ontological and functional heterogeneities in cellular ecosystems of primary and metastatic liver tumors, providing a foundation for future investigation of the underlying cellular mechanisms.
Assuntos
Células Endoteliais , Neoplasias Hepáticas , Humanos , Ecossistema , Neoplasias Hepáticas/genética , Perfilação da Expressão Gênica , Microambiente TumoralRESUMO
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer accounting for 90% of cases. It is a highly invasive and deadly cancer with a gradual onset. Polypyrimidine tract-binding protein 1 (PTBP1) is an important RNA-binding protein involved in RNA metabolism and has been linked to oncogenic splicing events. While the oncogenic role of PTBP1 in HCC cells has been established, the exact mechanism of action remains unclear. This study aimed to investigate the functional connection between PTBP1 and dysregulated splicing events in HCC. Through immunoprecipitation-mass spectrometry analyses, we discovered that the proteins bound to PTBP1 were significantly enriched in the complex responsible for the alternative splicing of FGFR2 (fibroblast growth factor receptor 2). Further RNA immunoprecipitation and quantitative PCR assays confirmed that PTBP1 down-regulated the FGFR2-IIIb isoform levels and up-regulated the FGFR2-IIIc isoform levels in HCC cells, leading to a switch from FGFR2-IIIb to FGFR2-IIIc isoforms. Subsequent functional evaluations using CCK-8, transwell, and plate clone formation assays in HCC cell lines HepG2 and Huh7 demonstrated that FGFR2-IIIb exhibited tumor-suppressive effects, while FGFR2-IIIc displayed tumor-promoting effects. In conclusion, this study provides insights into the PTBP1-mediated alternative splicing mechanism in HCC progression, offering a new theoretical basis for the prevention and treatment of this malignancy. Mechanistically, the isoform switch from FGFR2-IIIb to FGFR2-IIIc promoted epithelial-mesenchymal transformation (EMT) of HCC cells and activated the FGFR cascades ERK and AKT pathways.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/metabolismo , Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Isoformas de Proteínas/genética , Processamento Alternativo , RNA/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/genética , Ribonucleoproteínas Nucleares Heterogêneas/metabolismo , Proteína de Ligação a Regiões Ricas em Polipirimidinas/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/metabolismoRESUMO
Although emerging evidence has established the roles of miRNAs in hepatocellular carcinoma (HCC), the global functional implication of miRNAs in this malignancy remains largely uncharacterized. Here, we aim to systematically identify novel miRNAs involved in HCC and clarify the function and mechanism of specific novel candidate miRNA(s) in this malignancy. Through an integrative omics approach, we identified ten HCC-associated functional modules and a collection of candidate miRNAs. Among them, we demonstrated that miR-424-3p, exhibiting strong associations with extracellular matrix (ECM), promotes HCC cells migration and invasion in vitro and facilitates HCC metastasis in vivo. We further demonstrated that SRF is a direct functional target of miR-424-3p, and is required for the oncogenic activity of miR-424-3p. Finally, we found that miR-424-3p reduces the interferon pathway by attenuating the transactivation of SRF on STAT1/2 and IRF9 genes, which in turn enhances the matrix metalloproteinases (MMPs)-mediated ECM remodeling. This study provides comprehensive functional relevance of miRNAs in HCC by an integrative omics analysis, and further clarifies that miR-424-3p in ECM functional module plays an oncogenic role via reducing the SRF-STAT1/2 axis in this malignancy.
RESUMO
Hepatocellular carcinoma(HCC) is one of the most common forms of cancer, and accounts for a high proportion of cancer-associated deaths. Growing evidences have demonstrated that non- protein-coding regions of the genome could give rise to transcripts, termed noncoding RNA (ncRNA), that form novel functional layers of the cellular activity. ncRNAs are implicated in different molecular mechanisms and functions at transcriptional, translational and post-translational levels. An increasing number of studies have demonstrated a complex array of molecular and cellular functions of ncRNAs in different stages of the HCC tumorigenesis, either in an oncogenic or tumor-suppressive manner. As a result, several pre-clinical studies have highlighted the great potentials of ncRNAs as novel biomarkers for cancer diagnosis or therapeutics in targeting HCC progression. In this review, we briefly described the characteristics of several representative ncRNAs and summarized the latest findings of their roles and mechanisms in the development of HCC, in order to better understand the cancer biology and their potential clinical applications in this malignancy.
Assuntos
Biomarcadores Tumorais/metabolismo , Carcinoma Hepatocelular/patologia , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/patologia , RNA Longo não Codificante/genética , Animais , Biomarcadores Tumorais/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismoRESUMO
The outer membrane (OM) is an essential barrier that guards Gram-negative bacteria from diverse environmental insults. Besides functioning as a chemical gatekeeper, the OM also contributes towards the strength and stiffness of cells and allows them to sustain mechanical stress. Largely influenced by studies of Escherichia coli, the OM is viewed as a rigid barrier where OM proteins and lipopolysaccharides display restricted mobility. Here the discussion is extended to other bacterial species, with a focus on Myxococcus xanthus. In contrast to the rigid OM paradigm, myxobacteria possess a relatively fluid OM. It is concluded that the fluidity of the OM varies across environmental species, which is likely linked to their evolution and adaptation to specific ecological niches. Importantly, a fluid OM can endow bacteria with distinct functions for cell-cell and cell-environment interactions.
Assuntos
Membrana Externa Bacteriana , Myxococcus xanthus , Proteínas da Membrana Bacteriana Externa , Membrana Celular , Escherichia coli , Estilo de Vida , LipopolissacarídeosRESUMO
Hepatocellular carcinoma (HCC) is a common cancer worldwide. Hypoxia is an important feature of solid tumors, including HCC, and is also an important factor involved in malignancy progression. However, the identification of hypoxia-related long non-coding RNA (lncRNAs) and their prognostic value in HCC have not been systematically investigated. The aim of this study is to identify the features based on the hypoxia-related lncRNAs and evaluate their predictive value for HCC prognosis. Based on the integrated analysis of HCC transcriptome data from The Cancer Genome Atlas (TCGA), we had identified 233 potential hypoxia-related lncRNAs. We further evaluated the prognostic value of these lncRNAs and optimally established a 12-lncRNA (AC012676.1, PRR7-AS1, AC020915.2, AC008622.2, AC026401.3, MAPKAPK5-AS1, MYG1-AS1, AC015908.3, AC009275.1, MIR210HG, CYTOR and SNHG3) prognostic risk model. The Cox proportional hazards regression analysis revealed that the hypoxia risk score is a novel independent prognostic predictor for HCC patients, which outperforms the traditional clinical pathological factors. Gene set enrichment analysis (GSEA) showed that the hypoxia risk score reflects the activation of biological features related to cell proliferation and the inactivation of lipid metabolism processes. In summary, we had constructed a risk score model based on 12 hypoxia-related lncRNAs, which might be a promising prognostic predictor for HCC patients and highlight their potential roles in the prevention and treatment of this malignancy.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , RNA Longo não Codificante , Biomarcadores Tumorais/genética , Carcinoma Hepatocelular/genética , Humanos , Hipóxia/genética , Neoplasias Hepáticas/genética , Prognóstico , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismoRESUMO
Somatic copy number alterations (CNAs) are a genomic hallmark of cancers. Among them, the chromosome 17p13.1 deletions are recurrent in hepatocellular carcinoma (HCC). Here, utilizing an integrative omics analysis, we screened out a novel tumour suppressor gene within 17p13.1, myosin heavy chain 10 (MYH10). We observed frequent deletions (~38%) and significant down-regulation of MYH10 in primary HCC tissues. Deletion or decreased expression of MYH10 was a potential indicator of poor outcomes in HCC patients. Knockdown of MYH10 significantly promotes HCC cell migration and invasion in vitro, and overexpression of MYH10 exhibits opposite effects. Further, inhibition of MYH10 markedly potentiates HCC metastasis in vivo. We preliminarily elucidated the mechanism by which loss of MYH10 promotes HCC metastasis by facilitating EGFR pathway activation. In conclusion, our study suggests that MYH10, a candidate target gene for 17p13 deletion, acts as a tumour suppressor and may serve as a potential prognostic indicator for HCC patients.
Assuntos
Carcinoma Hepatocelular/etiologia , Deleção Cromossômica , Cromossomos Humanos Par 17 , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/etiologia , Cadeias Pesadas de Miosina/genética , Miosina não Muscular Tipo IIB/genética , Transdução de Sinais , Animais , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/mortalidade , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Biologia Computacional , Modelos Animais de Doenças , Suscetibilidade a Doenças , Receptores ErbB/metabolismo , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/patologia , Camundongos , Prognóstico , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Cells interact with their surrounding environment through surface proteins. However, knowledge gaps remain in understanding how these important types of proteins are transported and anchored on the cell surface. In the Gram-negative social bacterium, Myxococcus xanthus, a putative C-terminal sorting tag (MYXO-CTERM) is predicted to help direct 34 different proteins onto the cell surface. Here we investigate the sorting pathway for MYXO-CTERM proteins by using the TraA cell surface receptor as a paradigm. Deleting this motif from TraA abolishes the cell surface anchoring and results in extracellular secretion. Our findings indicate that conserved cysteines within the MYXO-CTERM are posttranslationally modified and are required for TraA cell surface localization and function. A region immediately upstream of these residues is predicted to be disordered and removing this motif caused a secretion defect and blocked cell surface anchoring. We further show that the type II secretion system is required for translocation across the outer membrane and that a cysteine-rich region directs TraA to the T2SS. Similar results were found with another MYXO-CTERM protein indicating our findings can be generalized. Further, we show the universal distribution of MXYO-CTERM motif across the Myxococcales order and provide a working model for sorting of these proteins.
Assuntos
Proteínas da Membrana Bacteriana Externa/fisiologia , Membrana Celular/fisiologia , Myxococcus xanthus/fisiologia , Transporte Proteico , Receptores de Superfície Celular/fisiologia , Sistemas de Secreção Tipo II/fisiologia , Domínios e Motivos de Interação entre Proteínas , Processamento de Proteína Pós-TraducionalRESUMO
To identify hepatocellular carcinoma (HCC)-implicated long noncoding RNAs (lncRNAs), we performed an integrative omics analysis by integrating mRNA and lncRNA expression profiles in HCC tissues. We identified a collection of candidate HCC-implicated lncRNAs. Among them, we demonstrated that an lncRNA, which is named as p53-stabilizing and activating RNA (PSTAR), inhibits HCC cell proliferation and tumorigenicity through inducing p53-mediated cell cycle arrest. We further revealed that PSTAR can bind to heterogeneous nuclear ribonucleoprotein K (hnRNP K) and enhance its SUMOylation and thereby strengthen the interaction between hnRNP K and p53, which ultimately leads to the accumulation and transactivation of p53. PSTAR is down-regulated in HCC tissues, and the low PSTAR expression predicts poor prognosis in patients with HCC, especially those with wild-type p53. Conclusion: This study sheds light on the tumor suppressor role of lncRNA PSTAR, a modulator of the p53 pathway, in HCC.
Assuntos
Carcinoma Hepatocelular/etiologia , Ribonucleoproteínas Nucleares Heterogêneas Grupo K/fisiologia , Neoplasias Hepáticas/etiologia , RNA Longo não Codificante/fisiologia , Sumoilação/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Humanos , Células Tumorais CultivadasRESUMO
The ability to recognize close kin confers survival benefits on single-celled microbes that live in complex and changing environments. Microbial kinship detection relies on perceptible cues that reflect relatedness between individuals, although the mechanisms underlying recognition in natural populations remain poorly understood. In myxobacteria, cells identify related individuals through a polymorphic cell surface receptor, TraA. Recognition of compatible receptors leads to outer membrane exchange among clonemates and fitness consequences. Here, we investigated how a single receptor creates a diversity in recognition across myxobacterial populations. We first show that TraA requires its partner protein TraB to function in cell-cell adhesion. Recognition is shown to be traA allele-specific, where polymorphisms within TraA dictate binding selectivity. We reveal the malleability of TraA recognition, and seemingly minor changes to its variable region reprogram recognition outcomes. Strikingly, we identify a single residue (A/P205) as a molecular switch for TraA recognition. Substitutions at this position change the specificity of a diverse panel of environmental TraA receptors. In addition, we engineered a receptor with unique specificity by simply creating an A205P substitution, suggesting that modest changes in TraA can lead to diversification of new recognition groups in nature. We hypothesize that the malleable property of TraA has allowed it to evolve and create social barriers between myxobacterial populations and in turn avoid adverse interactions with relatives.
Assuntos
Proteínas de Bactérias/metabolismo , Myxococcus xanthus/fisiologia , Receptores de Superfície Celular/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Aderência Bacteriana , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sítios de Ligação , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína , Receptores de Superfície Celular/química , Receptores de Superfície Celular/genética , Especificidade da EspécieRESUMO
Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Genomic copy number deletion at chromosome 14q31.1-32.13 was frequently observed in HCC; however, the relevant functional target(s) at that locus is not well determined. Here, we performed integrative genomic analyses and identified zinc finger CCCH-type containing 14 (ZC3H14) as a promising candidate at 14q31.1-32.13. We observed frequent copy number deletion (17.1%) and downregulation of ZC3H14 in primary HCC tissues. Downregulation of ZC3H14 was significantly associated with poor outcomes of patients with HCC. Overexpression of ZC3H14 in HCC cell lines significantly suppressed HCC cells growth in vitro and metastasis in vivo. In contrast, RNA interference silencing of ZC3H14 inhibited its tumor-suppressive function. Mechanismly, through combing bioinformatics analyses and experimental investigation, we demonstrated that loss of ZC3H14 promotes HCC progression through enhancing integrin pathway. This study suggests that ZC3H14 functions as a novel tumor suppressor and is a candidate prognostic biomarker for HCC patients.
Assuntos
Carcinoma Hepatocelular/patologia , Deleção Cromossômica , Cromossomos Humanos Par 14 , Regulação para Baixo , Integrinas/metabolismo , Neoplasias Hepáticas/patologia , Proteínas de Ligação a Poli(A)/genética , Transdução de Sinais , Animais , Carcinoma Hepatocelular/metabolismo , Feminino , Genes Supressores de Tumor , Xenoenxertos , Humanos , Neoplasias Hepáticas/metabolismo , Camundongos , Camundongos NusRESUMO
BACKGROUND & AIMS: Single nucleotide polymorphisms could affect risk for hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). We performed a germline copy number variation (CNV)-based genome-wide association study (GWAS) in populations of Chinese ancestry to search for germline CNVs that increase risk of HCC. METHODS: We conducted a CNV-based GWAS of 1583 HCC cases (persons with chronic HBV infection and HCC) and 1540 controls (persons with chronic HBV infection without HCC) in Chinese populations. Identified candidates were expressed in L-02, HepG2, or TP53-/- or wild-type HCT116 cells, and knocked down with short hairpin RNAs in HepG2, Bel-7402, and SMMC-7721 cells; proliferation, colony formation, and apoptosis were measured. Formation of xenograft tumors from cell lines was monitored in nude mice. Subcellular localization of ribosome proteins and levels or activity of p53 were investigated by co-immunoprecipitation, immunofluorescence, and immunoblot analyses. Levels of small nucleolar RNA H/ACA box 18-like 5 (SNORA18L5) were quantified by quantitative reverse transcription polymerase chain reaction. RESULTS: We identified a low-frequency duplication at chromosome 15q13.3 strongly associated with risk of HBV-related HCC (overall P = 3.17 × 10-8; odds ratio, 12.02). Copy numbers of the 15q13.3 duplication correlated with the expression of SNORA18L5 in liver tissues. Overexpression of SNORA18L5 increased HCC cell proliferation and growth of xenograft tumors in mice; knockdown reduced HCC proliferation and tumor growth. SNORA18L5 overexpression in HepG2 and SMMC-7721 cells inhibited p53-dependent cell cycle arrest and apoptosis. Overexpression of SNORA18L5 led to hyperactive ribosome biogenesis, increasing levels of mature 18S and 28S ribosomal RNAs and causing the ribosomal proteins RPL5 and RPL11 to stay in the nucleolus, which kept them from binding to MDM2. This resulted in increased MDM2-mediated ubiquitination and degradation of p53. Levels of SNORA18L5 were increased in HCC tissues compared with nontumor liver tissues and associated with shorter survival times of patients. CONCLUSIONS: In a CNV-based GWAS, we associated duplication at 15q13.3 with increased risk of HBV-related HCC. We found SNORA18L5 at this location to promote HCC cell proliferation and tumor growth in mice. SNORA18L5 increases ribosome biogenesis, facilitates ribosomal RNA maturation, and alters localization of RPL5 and RPL11, allowing for increased MDM2-mediated proteolysis of p53 and cell cycle arrest.
Assuntos
Carcinoma Hepatocelular/genética , Cromossomos Humanos Par 15/genética , Hepatite B Crônica/genética , Neoplasias Hepáticas/genética , RNA Nucleolar Pequeno/genética , Proteínas Ribossômicas/metabolismo , Proteína Supressora de Tumor p53/genética , Adulto , Animais , Povo Asiático/genética , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/virologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Variações do Número de Cópias de DNA/genética , Feminino , Duplicação Gênica , Regulação Neoplásica da Expressão Gênica/genética , Técnicas de Silenciamento de Genes , Estudo de Associação Genômica Ampla , Vírus da Hepatite B/isolamento & purificação , Hepatite B Crônica/patologia , Hepatite B Crônica/virologia , Humanos , Fígado/patologia , Fígado/virologia , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/virologia , Masculino , Camundongos , Camundongos Nus , Pessoa de Meia-Idade , RNA Interferente Pequeno/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The ability to recognize self and to recognize partnering cells allows microorganisms to build social networks that perform functions beyond the capabilities of the individual. In bacteria, recognition typically involves genetic determinants that provide cell surface receptors or diffusible signalling chemicals to identify proximal cells at the molecular level that can participate in cooperative processes. Social networks also rely on discriminating mechanisms to exclude competing cells from joining and exploiting their groups. In addition to their appropriate genotypes, cell-cell recognition also requires compatible phenotypes, which vary according to environmental cues or exposures as well as stochastic processes that lead to heterogeneity and potential disharmony in the population. Understanding how bacteria identify their social partners and how they synchronize their behaviours to conduct multicellular functions is an expanding field of research. Here, we review recent progress in the field and contrast the various strategies used in recognition and behavioural networking.
Assuntos
Bactérias/genética , Receptores de Superfície Celular/metabolismo , Bactérias/classificação , Fenômenos Fisiológicos Bacterianos , Biofilmes , Percepção de Quorum , Transdução de SinaisRESUMO
Bacterial cells in their native environments must cope with factors that compromise the integrity of the cell. The mechanisms of coping with damage in a social or multicellular context are poorly understood. Here we investigated how a model social bacterium, Myxococcus xanthus, approaches this problem. We focused on the social behavior of outer membrane exchange (OME), in which cells transiently fuse and exchange their outer membrane (OM) contents. This behavior requires TraA, a homophilic cell surface receptor that identifies kin based on similarities in a polymorphic region, and the TraB cohort protein. As observed by electron microscopy, TraAB overexpression catalyzed a prefusion OM junction between cells. We then showed that damage sustained by the OM of one population was repaired by OME with a healthy population. Specifically, LPS mutants that were defective in motility and sporulation were rescued by OME with healthy donors. In addition, a mutant with a conditional lethal mutation in lpxC, an essential gene required for lipid A biosynthesis, was rescued by Tra-dependent interactions with a healthy population. Furthermore, lpxC cells with damaged OMs, which were more susceptible to antibiotics, had resistance conferred to them by OME with healthy donors. We also show that OME has beneficial fitness consequences to all cells. Here, in merged populations of damaged and healthy cells, OME catalyzed a dilution of OM damage, increasing developmental sporulation outcomes of the combined population by allowing it to reach a threshold density. We propose that OME is a mechanism that myxobacteria use to overcome cell damage and to transition to a multicellular organism.
Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Lipopolissacarídeos/metabolismo , Interações Microbianas/fisiologia , Myxococcus xanthus/fisiologia , Primers do DNA/genética , Aptidão Genética/fisiologia , Microscopia Eletrônica , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Mutagênese , Myxococcus xanthus/ultraestrutura , Reação em Cadeia da PolimeraseRESUMO
Genomic polymorphisms come in various forms including single nucleotide variations, translocations, insertions and copy number variations (CNVs). As a form of structural variation, the CNVs comprise common and rare forms based on their populational frequencies. Studies have demonstrated that certain CNVs are associated with risks for neuro-developmental diseases, viral infections, chronic inflammations, and cancers. With the development of high-resolution genome typing technologies such as microarrays and whole genome sequencing, the human genomic CNVs map has been continuously improved and refined. In-depth study of CNVs not only can provide comprehensive understanding for their structural variations and genetic evolution, but also provide new insights into genetic factors contributing to such diseases. In this paper, the general characteristics, pathogenesis and detection methods for the CNVs, as well as their association with human diseases are reviewed.
Assuntos
Variações do Número de Cópias de DNA , Predisposição Genética para Doença , HumanosRESUMO
Steady progress has been achieved in the medical genetics in China in 2015, as numerous original researches were published in the world's leading journals. Chinese scientists have made significant contributions to various fields of medical genetics, such as pathogenicity of rare diseases, predisposition of common diseases, somatic mutations of cancer, new technologies and methods, disease-related microRNAs (miRNAs), disease-related long non-coding RNAs (lncRNAs), disease-related competing endogenous RNAs (ceRNAs), disease-related RNA splicing and molecular evolution. In these fields, Chinese scientists have gradually formed the tendency, from common variants to rare variants, from single omic analyses to multipleomics integration analyses, from genetic discovery to functional confirmation, from basic research to clinical application. Meanwhile, the findings of Chinese scientists have been drawn great attentions of international peers. This review aims to provide an overall picture of the front in Chinese medical genetics, and highlights the important findings and their research strategy.