Altered Regulation of ELAVL1/HuR in HLA-B27–Expressing U937 Monocytic Cells
نویسندگان
چکیده
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. CONCLUSION 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.
منابع مشابه
Phosphorylation of STAT-1 Serine 727 Is Prolonged in HLA-B27-Expressing Human Monocytic Cells
A tissue antigen, HLA-B27, is strongly associated with a group of rheumatic diseases called spondyloarthritides. Despite the intensive research, the exact role of HLA-B27 in the pathogenesis of these diseases is still unclear. Here we studied whether HLA-B27 modulates the phosphorylation of signal transducer and activator of transcription 1 (STAT-1) serine 727 residue and the localization of ST...
متن کاملHLA-B27 Modulates Intracellular Growth of Salmonella Pathogenicity Island 2 Mutants and Production of Cytokines in Infected Monocytic U937 Cells
BACKGROUND Salmonella enterica serovar Enteritidis PT4 KS8822/88 replicates rapidly in HLA-B27-transfected human monocytic U937 cells. In this process, Salmonella pathogenicity island 2 (SPI-2) genes play a crucial role. Our previous study indicated that 118 Salmonella genes, including 8 SPI-2 genes were affected by HLA-B27 antigen during Salmonella infection of U937 cells. METHODS/PRINCIPAL ...
متن کاملHuman monocytic U937 cells kill Salmonella in vitro by NO-independent mechanisms.
Nitric oxide (NO) has a central role in host defense against intracellular microbes. HLA-B27 has been shown to directly modulate host-microbe interaction in vitro, leading to the impaired elimination of Salmonella in human monocytic U937 cells. Here, we studied whether impaired elimination of Salmonella would result from differences in NO production between HLA-B27- and HLA-A2-transfected U937 ...
متن کاملHLA-B27-transfected (Salmonella permissive) and HLA-A2-transfected (Salmonella nonpermissive) human monocytic U937 cells differ in their production of cytokines.
The cytokine secretion of the Salmonella-permissive, HLA-B27-positive U937 cells was examined, as it was previously shown that these cells kill Salmonella less efficiently than controls. Salmonella-permissive U937 cells showed upregulated production of interleukin 10 and to a lesser extent tumor necrosis factor alpha. HLA-B27-associated modulation of cytokine responses may have importance in th...
متن کاملEssential role of the RNA-binding protein HuR in progenitor cell survival in mice.
The RNA-binding protein HuR (also known as ELAV1) binds to the 3'-untranslated region of mRNAs and regulates transcript stability and translation. However, the in vivo functions of HuR are not well understood. Here, we report that murine HuR is essential for life; postnatal global deletion of Elavl1 induced atrophy of hematopoietic organs, extensive loss of intestinal villi, obstructive enteroc...
متن کامل