title: miR-199a-5p silencing regulates the unfolded protein response in chronic obstructive pulmonary disease and α1-antitrypsin deficiency.
abstract: BACKGROUND
  Retention of abnormal α1-antitrypsin (AAT) activates the unfolded protein response in AAT-deficient monocytes. The regulatory role of microRNAs (miRNAs) in unfolded protein responses and chronic obstructive pulmonary disease pathogenesis has not been investigated.
  
  
  OBJECTIVE
  To investigate miRNA expression and function in MM and ZZ monocytes and identify miRNA(s) regulating the unfolded protein response.
  
  
  METHODS
  Peripheral blood monocytes were isolated from asymptomatic and symptomatic MM and ZZ individuals for miRNA expression profiling and pyrosequencing analysis. miRNA/gene and protein expression was measured with quantitative polymerase chain reaction and Western blotting. Overexpression and inhibition studies were performed with pre-miR or anti-miR, respectively. Luciferase reporter genes were used to elucidate direct miRNA-target interactions. Inflammatory cytokines were detected using the Meso Scale Discovery Plex assays.
  
  
  RESULTS
  Forty-three miRNAs were differentially expressed, with miR-199a-5p most highly up-regulated in asymptomatic ZZ versus MM monocytes. miR-199a-2 promoter hypermethylation inhibits miR-199a-5p expression and was increased in symptomatic MM and ZZ monocytes compared with asymptomatic counterparts. GRP78, activating transcription factor 6, p50, and p65 were increased in symptomatic versus asymptomatic ZZ monocytes. Reciprocal down- or up-regulation of these markers was observed after miRNA modulation. Direct miR-199a-5p targeting of activating transcription factor 6, p50, and p65 by miR-199a-5p was demonstrated using luciferase reporter systems. Overexpression of miR-199a-5p also decreased other arms of the UPR and expression of cytokines that are not putative targets.
  
  
  CONCLUSIONS
  miR-199a-5p is a key regulator of the unfolded protein response in AAT-deficient monocytes, and epigenetic silencing of its expression regulates this process in chronic obstructive pulmonary disease.
authors.affiliation: 1 Respiratory Research Division, Department of Medicine, and.
authors.forename: Tidi
authors.initials: T
authors.lastname: Hassan
authors.forename: Tomás P
authors.initials: TP
authors.lastname: Carroll
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Buckley
authors.forename: Robert
authors.initials: R
authors.lastname: Cummins
authors.forename: Shane J
authors.initials: SJ
authors.lastname: O'Neill
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Greene
mesh_terms: D000328:Adult; D058070:Asymptomatic Diseases; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D016207:Cytokines / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008745:Methylation; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism; D010641:Phenotype; D016133:Polymerase Chain Reaction; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000235:genetics* / Q000378:metabolism; D017423:Sequence Analysis, RNA; D013312:Stress, Physiological; D056811:Unfolded Protein Response / Q000235:genetics* / Q000502:physiology; D015854:Up-Regulation; D019896:alpha 1-Antitrypsin Deficiency / Q000150:complications / Q000235:genetics* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D016207:Cytokines; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D035683:MicroRNAs; C531408:mirn199 microRNA, human