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Linoleic acid-induced expression of inducible nitric oxide synthase and cyclooxygenase II via p42/44 mitogen-activated protein kinase and nuclear factor-kappaB pathway in retinal pigment epithelial cells.
Exp Eye Res. 2007 Nov; 85(5):667-77.EE

Abstract

High linoleic acid (LA) intake is known to correlate with age-related macular degeneration (AMD), but the molecular mechanisms remain unclear. This study was conducted to investigate the effects of LA on expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase II (COX-2) and their associated signaling pathways in human retinal pigment epithelial (RPE) cells. ARPE-19 cells were treated with different concentrations of LA. Expressions of iNOS and COX-2 were examined using semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. Concentrations of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) in the culture medium were determined by enzyme-link immunosorbent assay (ELISA). Activation of p42/44, p38, JNK mitogen-activated protein kinase (MAPK) and nuclear factors (NF)-kappaB were evaluated by Western blot analysis and electrophoretic mobility shift assay (EMSA). We found that LA induced expression of iNOS and COX-2 in RPE cells at the mRNA and protein levels in a time-and dose-dependent manner. Upregulation of iNOS and COX-2 resulted in increased production of NO and PGE(2). Moreover, LA caused degradation of IkappaB and increased NF-kappaB DNA binding activity. Effects of LA-induced iNOS and COX-2 expression were inhibited by a NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). LA activated p42/44, but not p38 or JNK MAPK. Inhibition of p42/44 activity by PD98059 significantly reduced LA-induced activation of NF-kappaB. Linoleic acid-induced expression of iNOS and COX-2 as well as PGE(2) and NO release in RPE cells were sequentially mediated through activation of p42/p44, MAPK, then NF-kappaB. These results may provide new insights into both mechanisms of LA action on RPE cells and pathogenesis of age-related macular degeneration.

Authors+Show Affiliations

Department of Ophthalmology, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd, Taipei, Taiwan.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17825288

Citation

Fang, I-Mo, et al. "Linoleic Acid-induced Expression of Inducible Nitric Oxide Synthase and Cyclooxygenase II Via P42/44 Mitogen-activated Protein Kinase and Nuclear factor-kappaB Pathway in Retinal Pigment Epithelial Cells." Experimental Eye Research, vol. 85, no. 5, 2007, pp. 667-77.
Fang IM, Yang CH, Yang CM, et al. Linoleic acid-induced expression of inducible nitric oxide synthase and cyclooxygenase II via p42/44 mitogen-activated protein kinase and nuclear factor-kappaB pathway in retinal pigment epithelial cells. Exp Eye Res. 2007;85(5):667-77.
Fang, I. M., Yang, C. H., Yang, C. M., & Chen, M. S. (2007). Linoleic acid-induced expression of inducible nitric oxide synthase and cyclooxygenase II via p42/44 mitogen-activated protein kinase and nuclear factor-kappaB pathway in retinal pigment epithelial cells. Experimental Eye Research, 85(5), 667-77.
Fang IM, et al. Linoleic Acid-induced Expression of Inducible Nitric Oxide Synthase and Cyclooxygenase II Via P42/44 Mitogen-activated Protein Kinase and Nuclear factor-kappaB Pathway in Retinal Pigment Epithelial Cells. Exp Eye Res. 2007;85(5):667-77. PubMed PMID: 17825288.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Linoleic acid-induced expression of inducible nitric oxide synthase and cyclooxygenase II via p42/44 mitogen-activated protein kinase and nuclear factor-kappaB pathway in retinal pigment epithelial cells. AU - Fang,I-Mo, AU - Yang,Chang-Hao, AU - Yang,Chung-May, AU - Chen,Muh-Shy, Y1 - 2007/08/06/ PY - 2007/03/13/received PY - 2007/07/14/revised PY - 2007/07/25/accepted PY - 2007/9/11/pubmed PY - 2008/2/22/medline PY - 2007/9/11/entrez SP - 667 EP - 77 JF - Experimental eye research JO - Exp Eye Res VL - 85 IS - 5 N2 - High linoleic acid (LA) intake is known to correlate with age-related macular degeneration (AMD), but the molecular mechanisms remain unclear. This study was conducted to investigate the effects of LA on expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase II (COX-2) and their associated signaling pathways in human retinal pigment epithelial (RPE) cells. ARPE-19 cells were treated with different concentrations of LA. Expressions of iNOS and COX-2 were examined using semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. Concentrations of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) in the culture medium were determined by enzyme-link immunosorbent assay (ELISA). Activation of p42/44, p38, JNK mitogen-activated protein kinase (MAPK) and nuclear factors (NF)-kappaB were evaluated by Western blot analysis and electrophoretic mobility shift assay (EMSA). We found that LA induced expression of iNOS and COX-2 in RPE cells at the mRNA and protein levels in a time-and dose-dependent manner. Upregulation of iNOS and COX-2 resulted in increased production of NO and PGE(2). Moreover, LA caused degradation of IkappaB and increased NF-kappaB DNA binding activity. Effects of LA-induced iNOS and COX-2 expression were inhibited by a NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). LA activated p42/44, but not p38 or JNK MAPK. Inhibition of p42/44 activity by PD98059 significantly reduced LA-induced activation of NF-kappaB. Linoleic acid-induced expression of iNOS and COX-2 as well as PGE(2) and NO release in RPE cells were sequentially mediated through activation of p42/p44, MAPK, then NF-kappaB. These results may provide new insights into both mechanisms of LA action on RPE cells and pathogenesis of age-related macular degeneration. SN - 0014-4835 UR - https://www.unboundmedicine.com/medline/citation/17825288/Linoleic_acid_induced_expression_of_inducible_nitric_oxide_synthase_and_cyclooxygenase_II_via_p42/44_mitogen_activated_protein_kinase_and_nuclear_factor_kappaB_pathway_in_retinal_pigment_epithelial_cells_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0014-4835(07)00211-4 DB - PRIME DP - Unbound Medicine ER -