title: HnRNP A1/A2 and SF2/ASF regulate alternative splicing of interferon regulatory factor-3 and affect immunomodulatory functions in human non-small cell lung cancer cells.
abstract: Heterogeneous nuclear ribonucleoparticule A1/A2 (hnRNP A1/A2) and splicing factor 2/alternative splicing factor (SF2/ASF) are pivotal for precursor messenger RNA (pre-mRNA) splicing. Interferon regulatory factor-3 (IRF-3) plays critical roles in host defense against viral and microbial infection. Truncated IRF-3 proteins resulting from alternative splicing have been identified and characterized as functional antagonists to full-length IRF-3. In this study, we examined the molecular mechanism for splicing regulation of IRF-3 pre-mRNA and first reported the regulatory effect of hnRNP A1/A2 and SF2/ASF on IRF-3 splicing and activation. RNA interference-mediated depletion of hnRNP A1/A2 or SF2/ASF in human non-small cell lung cancer (NSCLC) cells increased exclusion of exons 2 and 3 of IRF-3 gene and reduced expression levels of IRF-3 protein and IRF-3 downstream effector molecules interferon-beta and CXCL10/IP-10. In addition, direct binding of hnRNP A1 and SF2/ASF to specific binding motifs in IRF-3 intron 1 was confirmed by RNA electrophoretic mobility shift assay. Subsequent minigene splicing assay showed that IRF-3 minigenes with mutated hnRNPA 1/A2 or SF2/ASF binding motifs increased exclusion of exons 2 and 3. Moreover, knockdown of hnRNP A1/A2 or SF2/ASF in NSCLC cells reinforced phytohemagglutinin-induced tumor necrosis factor-alpha release by peripheral blood mononuclear cells (PBMC) but suppressed that of interleukin-10 in NSCLC/PBMC co-cultures. Taken together, our results suggest that specific knockdown for hnRNP A1/A2 or SF2/ASF increase exclusion of exons 2 and 3 of IRF-3 pre-mRNA and influence immunomodulatory functions of human NSCLC cells.
authors: Department of Geriatrics, Peking University First Hospital, Beijing, China.
authors: Rong
authors: R
authors: Guo
authors: Yong
authors: Y
authors: Li
authors: Jinying
authors: J
authors: Ning
authors: Dan
authors: D
authors: Sun
authors: Lianjun
authors: L
authors: Lin
authors: Xinmin
authors: X
authors: Liu
mesh_terms: D017398:Alternative Splicing; D001483:Base Sequence; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D045744:Cell Line, Tumor; D054357:Chemokine CXCL10 / Q000235:genetics / Q000276:immunology; D018920:Coculture Techniques; D005091:Exons; D005786:Gene Expression Regulation; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D006801:Humans; D056747:Immunomodulation; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000276:immunology*; D016899:Interferon-beta / Q000235:genetics / Q000276:immunology; D007438:Introns; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000473:pathology; D008175:Lung Neoplasms / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D012322:RNA Precursors / Q000235:genetics / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D000068103:Serine-Arginine Splicing Factors; D015398:Signal Transduction
chemical_list: C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D050838:Interferon Regulatory Factor-3; D009687:Nuclear Proteins; D012322:RNA Precursors; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C439768:hnRNP A2; D000068103:Serine-Arginine Splicing Factors; D016899:Interferon-beta
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