Project description:We identified several hub genes and key pathways associated with GAC initiation and progression by analysising the microarray data on DEGs, whcih provided a detailed molecular mechanism underlying GAC occurrence and progression.
Project description:Dysregulated transcription due to disruption in histone lysine methylation dynamics is an established contributor to tumorigenesis. However, whether analogous pathologic epigenetic mechanisms act directly on the ribosome to advance oncogenesis is unclear. Here we find that trimethylation of the core ribosomal protein L40 at lysine 22 (rpL40K22me3) by the lysine methyltransferase (KMT) SMYD5 regulates mRNA translation output to promote gastric adenocarcinoma (GAC) malignant progression with lethal peritoneal ascites. A biochemical-proteomic strategy identifies the mono-ubiquitin fusion protein partner rpL40 as the principal physiologic substrate of SMYD5 across diverse samples. Inhibiting the SMYD5-rpL40K22me3 axis in GAC cell lines reprograms protein synthesis to attenuate oncogenic gene expression signatures. SMYD5 and rpL40K22me3 are upregulated in GAC patient samples and negatively correlate with clinical outcomes. SMYD5 ablation in vivo in familial and sporadic mouse models of malignant GAC blocks metastatic disease including peritoneal carcinomatosis (PC). Suppressing SMYD5 methylation of rpL40 inhibits human cancer cell and patient-derived GAC xenograft growth and renders them hypersensitive to PI3K/mTOR inhibitors. Finally, combining SMYD5 depletion with PI3K/mTOR inhibition and CAR-T administration cures an otherwise lethal in vivo mouse model of aggressive GAC-derived PC. Together, our work uncovers a ribosome-based epigenetic mechanism that facilitates evolution of malignant GAC and nominates SMYD5 targeting as part of a potential cornerstone combination therapy to treat a deadly cancer.
Project description:The gene GLS generates the phosphate activated glutaminase C (GAC) isoform by alternative splicing. GAC, compared to the other isoform, kidney-type glutaminase (KGA), has been characterized as more active and particularly important for cancer cell growth. Very little is known about post-translational modifications regulating GAC function. Hereby we describe the identification of a phosphorylation on the serine 95, located at the GLS N-terminus, a domain shared by both isoforms. A GAC phosphomimetic mutant (S95D) ectopically expressed in breast cancer cells presented decreased enzymatic activity, and its expression impacted on cell’s glutamine uptake, glutamate release and intracellular glutamate levels (compared to expressing wild type GAC) without changing GAC sub-cellular localization. Curiously, replacing S95 by an alanine in the ectopically expressed GAC (S95A) increased cell proliferation and migration. Taken together, these results reveal that GAC is post-translationally regulated by phosphorylation, which impacts on cancer phenotype.
Project description:The phylum of Apicomplexa groups intracellular parasites that employ substrate-dependent gliding motility to invade host cells, egress from the infected cells and cross biological barriers. The glideosome associated connector (GAC) is a conserved protein essential to this process. GAC facilitates the association of actin filaments with surface transmembrane adhesins and the efficient transmission of the force generated by myosin translocation of actin to the cell surface substrate. Here, we present the crystal structure of Toxoplasma gondii GAC and reveal a unique, supercoiled armadillo repeat region that adopts a closed ring conformation. Characterisation of the membrane binding interface within the C-terminal PH domain as well as an N-terminal fragment necessary for association with F-actin suggest that GAC adopts multiple conformations. A multi-conformational model for assembly of GAC within the glideosome is proposed
Project description:Lymph node metastasis is one of the main causes for the low survival rate of gastric cancer patients. Exploring key proteins players in the progression of gastric adenocarcinoma (GAC) may provide new prognostic parkers and therapeutic strategies. we applied proteomic analysis to compare tumor tissues from GAC patients with or without lymph node metastasis, and captured unique molecular features of GAC patients with LNM. Analysis of the phosphoproteome provided a snapshot of abnormal phosphorylation signaling pathways and abnormal kinases activities. Furthermore, we found that TNXB and SPON1, two ECM proteins are associated with LNM status in GAC patients. Thus, our study suggests a number of proteins and kinases that has the potential to serve as prognosis markers to predict patient outcome.
Project description:Chip-seq experiment used to identify the binding sites of alternative σ factor σE in Streptomyces coelicolor. We access the binding sites with and without EtOH stress condition (see methods). To capture the binding of σE, the σE gene was tagged on genome by HA (Human Influenza hemagglutinin derived) epitope (TAC CCA TAC GAC GTC CCA GAC TAC GCT) on its C-terminus, wild type strain without tagged σE served as negative control.
Project description:The GacS/GacA two component regulatory system globally activates the production of secondary metabolites including phenazines in Pseudomonas chlororaphis 30-84. To better understand the regulatory role of the Gac system, we conducted RNA-seq analyses to determine the regulon of the response regulator GacA. Transcriptome analyses identified over 700 genes differentially regulated by GacA. Consistent with our previous findings, phenazine biosynthetic genes were significantly down-regulated in a gacA mutant. The expression levels of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS and pip were also decreased. Moreover, the expression of three none-coding RNAs (ncRNAs) including rsmX, rsmY and rsmZ was significantly decreased by gacA mutation consistent with the presence of GacA binding sites in their promoters. Our results also demonstrated that over-expression of rsmZ from a non-gac regulated promoter resulted in the restoration of AHL and phenazine production as well as the expression of other secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production was also investigated. Over-expression of rsmE, but not rsmA, resulted in decreased AHL production and phenazine gene expression in P. chlororaphis. Consistently, a mutation in rsmE bypassed the requirement of GacA in phenazine gene expression. On the contrary, constitutive expression of the phzI/phzR quorum sensing system was not able to rescue phenazine production in the gacA mutant indicating the direct impact of Gac system on the transcript stability of phenazine biosynthetic genes. Together, these results indicate that the Gac system regulates phenazine production at multiple levels and exerts its positive effect on AHL and phenazine biosynthesis via RsmZ and RsmE. A model is proposed to illustrate the GacA regulon in P. chlororaphis 30-84. A total of 6 samples were analyzed in AB medium + 2% casamino acids, Pseudomonas chlororaphis wild type strain (3 replicates); Pseudomonas chlororaphis gacA mutant (3 replicates).