title: Identification of Spinal Cord MicroRNA and Gene Signatures in a Model of Chronic Stress-Induced Visceral Hyperalgesia in Rat.
abstract: BACKGROUND
  Animal studies have shown that stress could induce epigenetic and transcriptomic alterations essential in determining the balance between adaptive or maladaptive responses to stress. We tested the hypothesis that chronic stress in rats deregulates coding and non-coding gene expression in the spinal cord, which may underline neuroinflammation and nociceptive changes previously observed in this model.
  
  
  METHODS
  Male Wistar rats were exposed to daily stress or handled, for 10 days. At day 11, lumbar spinal segments were collected and processed for mRNA/miRNA isolation followed by expression profiling using Agilent SurePrint Rat Exon and Rat miRNA Microarray platforms. Differentially expressed gene lists were generated using the dChip program. Microarrays were analyzed using the Ingenuity Pathways Analysis (IPA) tool from Ingenuity Systems. Multiple methods were used for the analysis of miRNA-mRNA functional modules. Quantitative real time RT-PCR for Interleukin 6 signal transducer (gp130), the Signal Transducer And Activator Of Transcription 3 (STAT3), glial fibrillary acidic protein and mir-17-5p were performed to confirm levels of expression.
  
  
  RESULTS
  Gene network analysis revealed that stress deregulated different inflammatory (IL-6, JAK/STAT, TNF) and metabolic (PI3K/AKT) signaling pathways. MicroRNA array analysis revealed a signature of 39 deregulated microRNAs in stressed rats. MicroRNA-gene network analysis showed that microRNAs are regulators of two gene networks relevant to inflammatory processes. Specifically, our analysis of miRNA-mRNA functional modules identified miR-17-5p as an important regulator in our model. We verified miR-17-5p increased expression in stress using qPCR and in situ hybridization. In addition, we observed changes in the expression of gp130 and STAT3 (involved in intracellular signaling cascades in response to gp130 activation), both predicted targets for miR-17-5p. A modulatory role of spinal mir17-5p in the modulation of visceral sensitivity was confirmed in vivo.
  
  
  CONCLUSIONS
  Using an integrative high throughput approach, our findings suggest a link between miR-17-5p increased expression and gp130/STAT3 activation providing new insight into the possible mechanisms mediating the effect of chronic stress on neuroinflammation in the spinal cord.
authors.affiliation: Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America; CURE Center, Veterans Administration, Greater Los Angeles, California, United States of America.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bradesi
authors.affiliation: Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America; Inflammatory Bowel Disease Center, and Neuroendocrine Assay Core, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Iordanes
authors.initials: I
authors.lastname: Karagiannides
authors.affiliation: Inflammatory Bowel Disease Center, and Neuroendocrine Assay Core, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Bakirtzi
authors.affiliation: Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America; Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Swapna Mahurkar
authors.initials: SM
authors.lastname: Joshi
authors.affiliation: Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Georgios
authors.initials: G
authors.lastname: Koukos
authors.affiliation: Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Iliopoulos
authors.affiliation: Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America; Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Charalabos
authors.initials: C
authors.lastname: Pothoulakis
authors.affiliation: Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America.
authors.forename: Emeran A
authors.initials: EA
authors.lastname: Mayer
mesh_terms: D000818:Animals; D050822:Cytokine Receptor gp130 / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D006930:Hyperalgesia / Q000378:metabolism* / Q000473:pathology; D053612:Janus Kinases / Q000096:biosynthesis; D008297:Male; D035683:MicroRNAs / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology; D013315:Stress, Psychological / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D005904:Glial Fibrillary Acidic Protein; C000601368:MIRN17 microRNA, rat; D035683:MicroRNAs; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D014409:Tumor Necrosis Factor-alpha; D050822:Cytokine Receptor gp130; D053612:Janus Kinases