Crocin suppresses LPS-stimulated expression of inducible nitric oxide synthase by upregulation of heme oxygenase-1 via calcium/calmodulin-dependent protein kinase 4.
Crocin is a water-soluble carotenoid pigment that is primarily used in various cuisines as a seasoning and coloring agent, as well as in traditional medicines for the treatment of edema, fever, and hepatic disorder. In this study, we demonstrated that crocin markedly induces the expression of heme oxygenase-1 (HO-1) which leads to an anti-inflammatory response. Crocin inhibited inducible nitric oxide synthase (iNOS) expression and nitric oxide production via downregulation of nuclear factor kappa B activity in lipopolysaccharide- (LPS-) stimulated RAW 264.7 macrophages. These effects were abrogated by blocking of HO-1 expression or activity. Crocin also induced Ca(2+) mobilization from intracellular pools and phosphorylation of Ca(2+)/calmodulin-dependent protein kinase 4 (CAMK4). CAMK4 knockdown and kinase-dead mutant inhibited crocin-mediated HO-1 expression, Nrf2 activation, and phosphorylation of Akt, indicating that HO-1 expression is mediated by CAMK4 and that Akt is a downstream mediator of CAMK4 in crocin signaling. Moreover, crocin-mediated suppression of iNOS expression was blocked by CAMK4 inhibition. Overall, these results suggest that crocin suppresses LPS-stimulated expression of iNOS by inducing HO-1 expression via Ca(2+)/calmodulin-CAMK4-PI3K/Akt-Nrf2 signaling cascades. Our findings provide a novel molecular mechanism for the inhibitory effects of crocin against endotoxin-mediated inflammation.
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735, Republic of Korea.
Ji-Hee
JH
Kim
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735, Republic of Korea.
Ga-Young
GY
Park
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735, Republic of Korea.
Soo Young
SY
Bang
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735, Republic of Korea.
Sun Young
SY
Park
Department of Dental Pharmacology, School of Dentistry, Yangsan Campus of Pusan National University, Yangsan 626-870, Republic of Korea.
Soo-Kyung
SK
Bae
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Jangjeon-dong, Keumjeong-gu, Busan 609-735, Republic of Korea.
YoungHee
Y
Kim
D000818:Animals; D002118:Calcium / Q000378:metabolism; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002338:Carotenoids / Q000494:pharmacology*; D002460:Cell Line; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*
D002147:Calmodulin; D008070:Lipopolysaccharides; D002338:Carotenoids; C029036:crocin; D052247:Nitric Oxide Synthase Type II; D051547:Heme Oxygenase-1; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; C517685:Camk4 protein, mouse; D002118:Calcium