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Whole transcriptome analysis reveals a role for OGG1-initiated DNA repair signaling in airway remodeling.

ABSTRACT: Reactive oxygen species (ROS) generated by environmental exposures, and endogenously as by-products of respiration, oxidatively modify biomolecules including DNA. Accumulation of ROS-induced DNA damage has been implicated in various diseases that involve inflammatory processes, and efficient DNA repair is considered critical in preventing such diseases. One of the most abundant DNA base lesions is 7,8-dihydro-8-oxoguanine (8-oxoG), which is repaired by the 8-oxoguanine DNA glycosylase 1 (OGG1)-initiated base-excision repair (OGG1-BER) pathway. Recent studies have shown that the OGG1-BER by-product 8-oxoG base forms a complex with cytosolic OGG1, activating small GTPases and downstream cell signaling in cultured cells and lungs. This implies that persistent OGG1-BER could result in signaling leading to histological changes in airways. To test this, we mimicked OGG1-BER by repeatedly challenging airways with its repair product 8-oxoG base. Gene expression was analyzed by RNA sequencing (RNA-Seq) and qRT-PCR, and datasets were evaluated by gene ontology and statistical tools. RNA-Seq analysis identified 3252 differentially expressed transcripts (2435 up- and 817 downregulated, ? 3-fold change). Among the upregulated transcripts, 2080 mRNAs were identified whose encoded protein products were involved in modulation of the actin family cytoskeleton, extracellular matrix, cell adhesion, cadherin, and cell junctions, affecting biological processes such as tissue development, cell-to-cell adhesion, cell communication, and the immune system. These data are supported by histological observations showing epithelial alterations, subepithelial fibrosis, and collagen deposits in the lungs. These data imply that continuous challenge by the environment and consequent OGG1-BER-driven signaling trigger gene expression consistent with airway remodeling.

SUBMITTER: Aguilera-Aguirre L

PROVIDER: S-EPMC4924473 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Whole transcriptome analysis reveals a role for OGG1-initiated DNA repair signaling in airway remodeling.

Aguilera-Aguirre Leopoldo L Hosoki Koa K Bacsi Attila A Radák Zsolt Z Sur Sanjiv S Hegde Muralidhar L ML Tian Bing B Saavedra-Molina Alfredo A Brasier Allan R AR Ba Xueqing X Boldogh Istvan I

Free radical biology & medicine 20150715

Reactive oxygen species (ROS) generated by environmental exposures, and endogenously as by-products of respiration, oxidatively modify biomolecules including DNA. Accumulation of ROS-induced DNA damage has been implicated in various diseases that involve inflammatory processes, and efficient DNA repair is considered critical in preventing such diseases. One of the most abundant DNA base lesions is 7,8-dihydro-8-oxoguanine (8-oxoG), which is repaired by the 8-oxoguanine DNA glycosylase 1 (OGG1)-i ...[more]

PMID: 26187872

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Project description:Purpose: The aim of this study is to evaluate the global gene expression induced by OGG1-BER product 8-oxoG in mouse airways. Methods: RNA extracted from individual mouse lungs (experimental group: n=5) were pooled and a total 1 M-NM-<g RNA was used for Next-Generation Sequencing (NGS) analyses on an Illumina HiSeq 1000 sequencing system. Sequence analysis were performed in duplicate. First- and second-strand synthesis, adapter ligation and amplification of the library were performed using the Illumina TruSeq Sample Preparation Kit as recommended by the manufacturer (Illumina). Library quality was evaluated by using an Agilent DNA-1000 chip on an Agilent 2100 Bioanalyzer. Library DNA templates were quantitated by qPCR using known reference starndards. Cluster formation of the library of DNA templates was performed using the TruSeq PE Cluster Kit v3 (Illumina) and the Illumina cBot workstation. Paired-end, 50-base sequencing was performed with a TruSeq SBS kit v3 (Illumina) on the Illumina HiSeq 1000 by protocols defined by the manufacturer. Base call conversion to sequence reads was performed using CASAVA-1.8.2. Sequence data were analyzed with the Bowtie2, Tophat2 and GFOLD programs. Processed data are presented as reads per kilobase transcript per million (RPKM), normalized to the experimental control (RNA from saline-challenged lungs) and reported as fold change (test/control). Results: We mapped an average of 24.76 million sequence reads per sample and identified 23,337 transcripts in total RNA extracted from lungs of Balb/cJ mice as described in Methods. Approximately 10% of the transcripts showed differential expression between the saline-challenged control and 8-oxoguanine-challeged mouse lungs, with a fold change M-bM-^IM-%3.0. We validated the expression changes of 7 selected pro-inflammatory cytokines and chemokines of interest for our studies by qRT-PCR. Hierarchical clustering followed by Protein ANalysis THrough Evolutionary Relationships database (PANTHER) analysis of differentially expressed genes. Results showed overrepresentation of various biological functions (GO terms) including immune system process (GO:0002376; p=5.24e-12) among others. Pathway analysis (PANTHER) indicated that the most overrepresented pathway was inflammation mediated by chemokine and cytokine (P00031, p=<0.01). In addition to gene expression analysis, we confirmed OGG1M-bM-^@M-"8-oxoG-dependent RAS activation in lungs by active RAS pull-down assays, airways neutrophil accumulation by bronchoalveolar lavage fluid (BALF) differential cell counts and airway inflammation by histological examination (H&E staining) of lung sections. Conclusions: This is the first study at the whole-transcriptome level to show induction of innate immune response gene expression in mouse lungs after exposure to OGG1-BER product 8-oxoG. Balb/cJ mice (5 per group) were intranasally challenged with 8-oxoguanine (1 M-BM-5M, 60 M-BM-5l) for 30, 60 and 120 min. Control group mice were intranasally challenged with saline (60 M-BM-5l). RNA from individual mice whithin the same group was pooled and subjected to deep-sequencing analysis in duplicate using NGS on an Illumina HiSeq 1000 sequencing system. After alignment and processing, the resulting RPKM from treatment groups (8-oxoG-challenged) were normalized to the control group (saline-challenged).

Project description:Purpose: The aim of this study is to test whether global gene expression induced by multiple challenges with OGG1-BER product 8-oxoG in mouse airways is linked to airway remodeling. Methods: RNAs extracted from individual mouse lungs (experimental group: n=5) were pooled and a total 1 ?g RNA was used for Next-Generation Sequencing (NGS) analyses on an Illumina HiSeq 1000 sequencing system. Sequence analyses were performed in duplicate. First- and second-strand synthesis, adapter ligation and amplification of the library were performed using the Illumina TruSeq Sample Preparation Kit as recommended by the manufacturer (Illumina). Library quailty was evaluated by using an Agilent DNA-1000 chip on an Agilent 2100 Bioanalyzer. Library DNA templates were quantitated by qPCR using known reference standards. Cluster formation of the library of DNA templates was performed using the TruSeq PE Cluster Kit v3 (Illumina) and the Illumina cBot workstation. Paired-end, 50-base sequencing was performed with a TruSeq SBS kit v3 (Illumina) on the Illumina HiSeq 1000 by protocols defined by the manufacturer. Base call conversion to sequence reads was performed using CASAVA-1.8.2. Sequence data were analyzed with the Bowtie2, Tophat2 and GFOLD programs. Processed data are presented as reads per kilobase transcript per million (RPKM), normalized to the experimental control (RNA from saline challenged lungs) and reported as fold change (test/control). Results: We mapped an average of 31.41 million sequence reads per sample and identified 23,337 transcripts in total RNA extracted from lungs of Balb/cJ mice as described in Methods. Approximately 14% of the transcripts showed differential expression between the saline-challenged control and 8-oxoguanine-challeged mouse lungs, with a fold change ?3.0. We validated the expression changes of 18 selected EMT-related genes of interest for our studies by qRT-PCR. Hierarchical clustering followed by Protein ANalysis THrough Evolutionary Relationships database (PANTHER) analysis of differentially expressed genes was done using GENE-E online software from Broad Institute (http://www.broadinstitute.org/cancer/software/GENE-E/). Results from PANTHER analysis of upregulated transcripts (fold change ?3.0) showed overrepresentation of various biological functions (GO terms) including developmental process (GO:0032502, P=4.58E-33), system development (GO:0048731, P=9.16E-33), cellular process (GO:0009987, P= 5.52E-31), cell adhesion (GO:0007155, P= 8.63E-28) among others. Pathway analysis (PANTHER) indicated that the most overrepresented pathways were: cadherin signaling (P00012, P=6.62E-07), wnt signaling (P00057, P= 5.81E-06), integrin signaling (P00034, P= 1.09E-05) among others. In addition to gene expression analysis, we confirmed airway remodeling by histological examination (Hematoxylin and Eosin, Masson's trichrome staining) of lung sections at seven days from the last challenge (day 11). Conclusions: This is the first study showing a link between gene expression at whole-transcriptome level induced by chronic OGG1-BER (mimicked by multiple challenges with 8-oxoG) and airway remodeling, supported by histological structural changes in lungs. Balb/cJ mice (5 per group) were intranasally challenged with 8-oxoguanine (1 µM, 60 µl) for three times at days 0, 2 and 4. Control group mice were intranasally challenged with saline (60 µl). At 30, 60 and 120 min after the third challenge (day 4), mice were sacrificed and lungs were processed for RNA extraction. RNAs from individual mice within the same group were pooled and subjected to deep-sequencing analysis in duplicate using NSG on an Illumina HiSeq 1000 sequencing system. After alignment and processing, the resulting RPKM from treatment groups (8-oxoG-challenged) were normalized to control group (saline-challenged).

Project description:Purpose: The aim of this study is to evaluate the global gene expression induced by OGG1-BER product 8-oxoG in mouse airways. Methods: RNA extracted from individual mouse lungs (experimental group: n=5) were pooled and a total 1 μg RNA was used for Next-Generation Sequencing (NGS) analyses on an Illumina HiSeq 1000 sequencing system. Sequence analysis were performed in duplicate. First- and second-strand synthesis, adapter ligation and amplification of the library were performed using the Illumina TruSeq Sample Preparation Kit as recommended by the manufacturer (Illumina). Library quality was evaluated by using an Agilent DNA-1000 chip on an Agilent 2100 Bioanalyzer. Library DNA templates were quantitated by qPCR using known reference starndards. Cluster formation of the library of DNA templates was performed using the TruSeq PE Cluster Kit v3 (Illumina) and the Illumina cBot workstation. Paired-end, 50-base sequencing was performed with a TruSeq SBS kit v3 (Illumina) on the Illumina HiSeq 1000 by protocols defined by the manufacturer. Base call conversion to sequence reads was performed using CASAVA-1.8.2. Sequence data were analyzed with the Bowtie2, Tophat2 and GFOLD programs. Processed data are presented as reads per kilobase transcript per million (RPKM), normalized to the experimental control (RNA from saline-challenged lungs) and reported as fold change (test/control). Results: We mapped an average of 24.76 million sequence reads per sample and identified 23,337 transcripts in total RNA extracted from lungs of Balb/cJ mice as described in Methods. Approximately 10% of the transcripts showed differential expression between the saline-challenged control and 8-oxoguanine-challeged mouse lungs, with a fold change ≥3.0. We validated the expression changes of 7 selected pro-inflammatory cytokines and chemokines of interest for our studies by qRT-PCR. Hierarchical clustering followed by Protein ANalysis THrough Evolutionary Relationships database (PANTHER) analysis of differentially expressed genes. Results showed overrepresentation of various biological functions (GO terms) including immune system process (GO:0002376; p=5.24e-12) among others. Pathway analysis (PANTHER) indicated that the most overrepresented pathway was inflammation mediated by chemokine and cytokine (P00031, p=<0.01). In addition to gene expression analysis, we confirmed OGG1•8-oxoG-dependent RAS activation in lungs by active RAS pull-down assays, airways neutrophil accumulation by bronchoalveolar lavage fluid (BALF) differential cell counts and airway inflammation by histological examination (H&E staining) of lung sections. Conclusions: This is the first study at the whole-transcriptome level to show induction of innate immune response gene expression in mouse lungs after exposure to OGG1-BER product 8-oxoG.

Project description:Purpose: The aim of this study is to test whether global gene expression induced by multiple challenges with OGG1-BER product 8-oxoG in mouse airways is linked to airway remodeling. Methods: RNAs extracted from individual mouse lungs (experimental group: n=5) were pooled and a total 1 μg RNA was used for Next-Generation Sequencing (NGS) analyses on an Illumina HiSeq 1000 sequencing system. Sequence analyses were performed in duplicate. First- and second-strand synthesis, adapter ligation and amplification of the library were performed using the Illumina TruSeq Sample Preparation Kit as recommended by the manufacturer (Illumina). Library quailty was evaluated by using an Agilent DNA-1000 chip on an Agilent 2100 Bioanalyzer. Library DNA templates were quantitated by qPCR using known reference standards. Cluster formation of the library of DNA templates was performed using the TruSeq PE Cluster Kit v3 (Illumina) and the Illumina cBot workstation. Paired-end, 50-base sequencing was performed with a TruSeq SBS kit v3 (Illumina) on the Illumina HiSeq 1000 by protocols defined by the manufacturer. Base call conversion to sequence reads was performed using CASAVA-1.8.2. Sequence data were analyzed with the Bowtie2, Tophat2 and GFOLD programs. Processed data are presented as reads per kilobase transcript per million (RPKM), normalized to the experimental control (RNA from saline challenged lungs) and reported as fold change (test/control). Results: We mapped an average of 31.41 million sequence reads per sample and identified 23,337 transcripts in total RNA extracted from lungs of Balb/cJ mice as described in Methods. Approximately 14% of the transcripts showed differential expression between the saline-challenged control and 8-oxoguanine-challeged mouse lungs, with a fold change ≥3.0. We validated the expression changes of 18 selected EMT-related genes of interest for our studies by qRT-PCR. Hierarchical clustering followed by Protein ANalysis THrough Evolutionary Relationships database (PANTHER) analysis of differentially expressed genes was done using GENE-E online software from Broad Institute (http://www.broadinstitute.org/cancer/software/GENE-E/). Results from PANTHER analysis of upregulated transcripts (fold change ≥3.0) showed overrepresentation of various biological functions (GO terms) including developmental process (GO:0032502, P=4.58E-33), system development (GO:0048731, P=9.16E-33), cellular process (GO:0009987, P= 5.52E-31), cell adhesion (GO:0007155, P= 8.63E-28) among others. Pathway analysis (PANTHER) indicated that the most overrepresented pathways were: cadherin signaling (P00012, P=6.62E-07), wnt signaling (P00057, P= 5.81E-06), integrin signaling (P00034, P= 1.09E-05) among others. In addition to gene expression analysis, we confirmed airway remodeling by histological examination (Hematoxylin and Eosin, Masson's trichrome staining) of lung sections at seven days from the last challenge (day 11). Conclusions: This is the first study showing a link between gene expression at whole-transcriptome level induced by chronic OGG1-BER (mimicked by multiple challenges with 8-oxoG) and airway remodeling, supported by histological structural changes in lungs.

Project description:Activation of NLRP3 (nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3) inflammasome-mediating interleukin (IL)-1? secretion has emerged as an important component of inflammatory processes in atherosclerosis. Mitochondrial DNA (mtDNA) damage is detrimental in atherosclerosis, and mitochondria are central regulators of the nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 inflammasome. Human atherosclerotic plaques express increased mtDNA damage. The major DNA glycosylase, 8-oxoguanine glycosylase (OGG1), is responsible for removing the most abundant form of oxidative DNA damage.To test the role of OGG1 in the development of atherosclerosis in mouse.We observed that Ogg1 expression decreases over time in atherosclerotic lesion macrophages of low-density lipoprotein receptor (Ldlr) knockout mice fed a Western diet. Ogg1(-/-)Ldlr(-/-) mice fed a Western diet resulted in an increase in plaque size and lipid content. We found increased oxidized mtDNA, inflammasome activation, and apoptosis in atherosclerotic lesions and also higher serum IL-1? and IL-18 in Ogg1(-/-)Ldlr(-/-) mice than in Ldlr(-/-). Transplantation with Ogg1(-/-) bone marrow into Ldlr(-/-) mice led to larger atherosclerotic lesions and increased IL-1? production. However, transplantation of Ogg1(-/-)Nlrp3(-/-) bone marrow reversed the Ogg1(-/-) phenotype of increased plaque size. Ogg1(-/-) macrophages showed increased oxidized mtDNA and had greater amounts of cytosolic mtDNA and cytochrome c, increased apoptosis, and more IL-1? secretion. Finally, we found that proatherogenic miR-33 can directly inhibit human OGG1 expression and indirectly suppress both mouse and human OGG1 via AMP-activated protein kinase.OGG1 plays a protective role in atherogenesis by preventing excessive inflammasome activation. Our study provides insight into a new target for therapeutic intervention based on a link between oxidative mtDNA damage, OGG1, and atherosclerosis via NLRP3 inflammasome.

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Whole transcriptome analysis reveals a role for OGG1-initiated DNA repair signaling in airway remodeling.

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Whole transcriptome analysis reveals a role for OGG1-initiated DNA repair signaling in airway remodeling.

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