title: The level of nitric oxide regulates lipocalin-2 expression under inflammatory condition in RINm5F beta-cells.
abstract: We previously reported that proinflammatory cytokines (interleukin-1β and interferon-γ) induced the expression of lipocalin-2 (LCN-2) together with inducible nitric oxide synthase (iNOS) in RINm5F beta-cells. Therefore, we examined the effect of nitric oxide (NO) on LCN-2 expression in cytokines-treated RINm5F beta-cells. Additionally, we observed the effect of LCN-2 on cell viability. First, we found the existence of LCN-2 receptor and the internalization of exogenous recombinant LCN-2 peptide in RINm5F and INS-1 beta-cells. Next, the effects of NO on LCN-2 expression were evaluated. Aminoguanidine, an iNOS inhibitor and iNOS gene silencing significantly inhibited cytokines-induced LCN-2 expression while sodium nitroprusside (SNP), an NO donor potentiated it. Luciferase reporter assay showed that transcription factor NF-κB was not involved in LCN-2 expression. Both LCN-2 mRNA and protein stability assays were conducted. SNP did not affect LCN-2 mRNA stability, however, it significantly reduced LCN-2 protein degradation. The LCN-2 protein degradation was significantly attenuated by MG132, a proteasome inhibitor. Finally, the effect of LCN-2 on cell viability was evaluated. LCN-2 peptide treatment and LCN-2 overexpression significantly reduced cell viability. FACS analysis showed that LCN-2 induced the apoptosis of the cells. Collectively, NO level affects LCN-2 expression via regulation of LCN-2 protein stability under inflammatory condition and LCN-2 may reduce beta-cell viability by promoting apoptosis.
authors.affiliation: Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Seo-Yoon
authors.initials: SY
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Dong-Bin
authors.initials: DB
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Ko
authors.affiliation: Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Hyun-Jong
authors.initials: HJ
authors.lastname: Jang
authors.affiliation: Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Yang-Hyeok
authors.initials: YH
authors.lastname: Jo
authors.affiliation: Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address: mjunkim@catholic.ac.kr.
authors.forename: Myung-Jun
authors.initials: MJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival; D005786:Gene Expression Regulation; D007249:Inflammation / Q000235:genetics / Q000276:immunology; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology*; D053583:Interleukin-1beta / Q000276:immunology*; D000071068:Lipocalin-2 / Q000235:genetics* / Q000276:immunology; D009569:Nitric Oxide / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats
chemical_list: D053583:Interleukin-1beta; D000071068:Lipocalin-2; D012333:RNA, Messenger; D009569:Nitric Oxide; D007371:Interferon-gamma
keywords: Interferon-γ; Interleukin-1β; Lipocalin-2; Nitric oxide; RINm5F cells