Alteration of gene expression profiles during mycoplasma-induced malignant cell transformation

BACKGROUND: Mycoplasmas are the smallest microorganisms capable of self-replication. Our previous studies show that some mycoplasmas are able to induce malignant transformation of host mammalian cells. This malignant transformation is a multistage process with the early infection, reversible and irreversible stages, and similar to human tumor development in nature. The purpose of this study is to explore mechanisms for this malignant transformation. METHODS: To better understand mechanisms for this unique process, we examined gene expression profiles of C3H cells at different stages of the mycoplasma-induced transformation using cDNA microarray technology. A total of 1185 genes involved in oncogenesis, apoptosis, cell growth, cell-cycle regulation, DNA repair, etc. were examined. Differences in the expression of these genes were compared and analyzed using the computer software AtlasImage. RESULTS: Among 1185 genes screened, 135 had aberrant expression at the early infection stage, 252 at the reversible stage and 184 at the irreversible stage. At the early infection stage, genes with increased expression (92 genes) were twice more than those with decreased expression (42 genes). The global gene expression at the reversible stage appeared to be more volatile than that at any other stages but still resembled the profile at the early infection stage. The expression profile at the irreversible stage shows a unique pattern of a wide range of expression levels and an increased number of expressing genes, especially the cancer-related genes. Oncogenes and tumor suppressors are a group of molecules that showed significant changes in expression during the transformation. The majority of these changes occurred in the reversible and irreversible stages. A prolonged infection by mycoplasmas lead to the expression of more cancer related genes at the irreversible stage. CONCLUSION: The results indicate that the expression profiles correspond with the phenotypic features of the cells in the mycoplasma induced transformation process. The early mycoplasma infection stage shares a common phenomenon with many other acute infections, genes with increased expression significantly outnumbering those with decreased expression. The reversible stage is a transition stage between benignancy and malignancy at the molecular level. Aberrant expression of oncogenes and tumor repressors plays a key role in mycoplasma-induced malignant transformation

Production and Characterization of Chimeric Monoclonal Antibodies against Burkholderia pseudomallei and B. mallei Using the DHFR Expression System

Burkholderia pseudomallei (BP) and B. mallei (BM) are closely related gram-negative, facultative anaerobic bacteria which cause life-threatening melioidosis in human and glanders in horse, respectively. Our laboratory has previously generated and characterized more than 100 mouse monoclonal antibodies (MAbs) against BP and BM, according to in vitro and in vivo assay. In this study, 3 MAbs (BP7 10B11, BP7 2C6, and BP1 7F7) were selected to develop into chimeric mouse-human monoclonal antibodies (cMAbs) against BP and/or BM. For the stable production of cMAbs, we constructed 4 major different vector systems with a dihydrofolate reductase (DHFR) amplification marker, and optimized transfection/selection conditions in mammalian host cells with the single-gene and/or double-gene expression system. These 3 cMAbs were stably produced by the DHFR double mutant Chinese hamster ovarian (CHO)-DG44 cells. By ELISA and Western blot analysis using whole bacterial antigens treated by heat (65°C/90 min), sodium periodate, and proteinase K, the cMAb BP7 10B11 (cMAb CK1) reacted with glycoproteins (34, 38, 48 kDa in BP; 28, 38, 48 kDa in BM). The cMAb BP7 2C6 (cMAb CK2) recognized surface-capsule antigens with molecular sizes of 38 to 52 kDa, and 200 kDa in BM. The cMAb CK2 was weakly reactive to 14∼28, 200 kDa antigens in BP. The cMAb BP1 7F7 (cMAb CK3) reacted with lipopolysaccharides (38∼52 kDa in BP; 38∼60 kDa in B. thailandensis). Western blot results with the outer surface antigens of the 3 Burkholderia species were consistent with results with the whole Burkholderia cell antigens, suggesting that these immunodominant antigens reacting with the 3 cMAbs were primarily present on the outer surface of the Burkholderia species. These 3 cMAbs would be useful for analyzing the role of the major outer surface antigens in Burkholderia infection

Environmental humidity changes inferred from multi-indicators in the Jianghan Plain, Central China during the last 12,700 years

Time sequence of the JZ-2010 profile derived from AMS(14)C dating and the content of the sediment elements Ti, Rb and Sr, the Rb/Sr values as well as the granularity and the magnetic susceptibility are utilized to reconstruct the environmental humidity changes in the Jianghan Plain since 12,700 cal. BP. The comprehensive analyses of multiple alternative indicators indicate that the regional moisture turned from relatively dry to wet after the Late-Glacial period and reached its optimum until the mid-Holocene. However, the trend was punctuated by several decreased humidity phases. Beginning with the severe dry event approximately 4400-4100 cal. BP, the environment was dry as a whole, with modest humidity from approximately 3900 cal. BP. Humidity changes in the study area are dominated by the East Asian monsoon system, which is under the influence of the gradual southward migration of the ITCZ, driven by the summer solar insolation changes in the Northern Hemisphere due to orbital forcing. As the first attempt to apply Rb/Sr value and Ti concentration in tracing moisture evolution in a region with typical subtropical humid climate, this study highlights the different effects and consequences of the proxies throughout the palaeoenvironmental change process, and the impacts of regional topography that sustained tectonic subsidence since the Cretaceous as well as the southeast tilt that opened the plain to the summer monsoon. Moreover, the fluctuation of magnetic susceptibility is associated with the granularity feature, the reduction-oxidation conditions, and the impact of human factors on the natural sedimentary environments during the historic period in the Jianghan Plain.</p

Reduced expression of Paternally Expressed Gene-3 enhances somatic cell reprogramming through mitochondrial activity perturbation

Imprinted genes control several cellular and metabolic processes in embryonic and adult tissues. In particular, paternally expressed gene-3 (Peg3) is active in the adult stem cell population and during muscle and neuronal lineage development. Here we have investigated the role of Peg3 in mouse embryonic stem cells (ESCs) and during the process of somatic cell reprogramming towards pluripotency. Our data show that Peg3 knockdown increases expression of pluripotency genes in ESCs and enhances reprogramming efficiency of both mouse embryonic fibroblasts and neural stem cells. Interestingly, we observed that altered activity of Peg3 correlates with major perturbations of mitochondrial gene expression and mitochondrial function, which drive metabolic changes during somatic cell reprogramming. Overall, our study shows that Peg3 is a regulator of pluripotent stem cells and somatic cell reprogramming.We thank Marie Victoire Neguembor, Martina Pesaresi and Sergi Angel Bonilla Pons for suggestions on the manuscript and Umberto Di Vicino for technical support. We thank Angelique di Domenico and the group of Antonella Consiglio for providing us the OPA1, DRP1 and VDAC1 antibodies. We thank Mari Carmen Ortells and the group of Bill Keyes for providing us the OXPHOS antibody. The pInducer10-mir-RUP-PheS plasmid was a gift from Stephen Elledge (Addgene plasmid # 44011). We are grateful for support from Ministerio de Economia y Competitividad and FEDER funds (SAF2011-28580, BFU2014-54717-P, and BFU2015-71984-ERC to M.P.C.), Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (2014 SGR1137 to M.P.C.), the European Union's Horizon 2020 research and innovation programme under grant agreement CellViewer No 686637 (to M.P.C.), Spanish Ministry of Economy and Competitiveness, 'Centro de Excelencia Severo Ochoa 2013-2017 and the CERCA Programme/Generalitat de Catalunya (to M.P.C.), People Programme Marie Curie Actions of the European Union's Seventh Framework Programme (FP7/2007-2013/, n° 290123 to I.T.), La Caixa international PhD fellowship (to F.S.), Ministerio de Ciencia e Innovació FPI (to F.A.) and Ministerio de Ciencia e Innovación FPI-Severo Ochoa (to A.C.G)