title: Altered regulation of ELAVL1/HuR in HLA-B27-expressing U937 monocytic cells.
abstract: OBJECTIVE
  To investigate the role of HLA-B27 expression in the regulation of RNA binding protein (RBP) Embryonic Lethal Abnormal Vision (ELAV) L1/Human antigen R (HuR) expression in Salmonella-infected or LPS-stimulated human monocytic cells, since HuR is a critical regulator of the post-transcriptional fate of many genes (e.g. TNFα) important in inflammatory response.
  
  
  METHODS
  U937 monocytic cells were stably transfected with pSV2neo resistant vector (mock), wild type HLA-B27, or mutated HLA-B27 with amino acid substitutions in the B pocket. Cells were differentiated, infected with Salmonella enteritidis or stimulated with lipopolysaccharide. The expression levels of HuR protein and cleavage products (CP1 and CP2) were detected by Western blotting and flow cytometry. Specific inhibitors were used to study the role of PKR and p38 in HuR expression and generation of CPs. TNFα and IL-10 secretion after p38 and PKR inhibition were measured by ELISA.
  
  
  RESULTS
  Full length HuR is overexpressed and HuR cleavage is disturbed in U937 monocytic cells expressing HLA-B27 heavy chains (HC). Increased full length HuR expression, disturbed cleavage and reduced dependence on PKR after infection correlate with the expression of glutamic acid 45 in the B pocket that is linked to the misfolding of HLA-B27.
  
  
  CONCLUSIONS
  Results show that the expression of HLA-B27 HCs modulates the intracellular environment of U937 monocyte/macrophages by altering HuR regulation. This phenomenon is at least partly dependent on the misfolding feature of the B27 molecule. Since HuR is an important regulator of multiple genes involved in inflammatory response observations offer an explanation how HLA-B27 may modulate inflammatory response.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland. anna.sahlberg@utu.fi
authors.forename: Anna S
authors.initials: AS
authors.lastname: Sahlberg
authors.forename: Marja
authors.initials: M
authors.lastname: Ruuska
authors.forename: Kaisa
authors.initials: K
authors.lastname: Granfors
authors.forename: Markus A
authors.initials: MA
authors.lastname: Penttinen
mesh_terms: D051959:ELAV Proteins / Q000378:metabolism*; D000067780:ELAV-Like Protein 1; D015870:Gene Expression; D018698:Glutamic Acid / Q000378:metabolism; D015796:HLA-B27 Antigen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D016753:Interleukin-10 / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D011725:Pyridines / Q000494:pharmacology; D012475:Salmonella / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D015796:HLA-B27 Antigen; D007093:Imidazoles; D011725:Pyridines; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018698:Glutamic Acid; D048051:p38 Mitogen-Activated Protein Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole
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