Leucine-Rich Repeat Kinase 2 (LRRK2) Stimulates IL-1ß-Mediated Inflammatory Signaling through Phosphorylation of RCAN1.

Leucine-rich repeat kinase 2 (LRRK2) is a Ser/Thr kinase having mixed lineage kinase-like and GTPase domains, controlling neurite outgrowth and neuronal cell death. Evidence suggests that LRRK2 is involved in innate immune response signaling, but the underlying mechanism is yet unknown. A novel protein inhibitor of phosphatase 3B, RCAN1, is known to positively regulate inflammatory signaling through modulation of several intracellular targets of interleukins in immune cells. In the present study, we report that LRRK2 phosphorylates RCAN1 (RCAN1-1S) and is markedly up-regulated during interleukin-1ß (IL-1ß) treatment. During IL-1ß treatment, LRRK2-mediated phosphorylation of RCAN1 promoted the formation of protein complexes, including that between Tollip and RCAN1. LRRK2 decreased binding between Tollip and IRAK1, which was accompanied by increased formation of the IRAK1-TRAF6 complex. TAK1 activity was significantly enhanced by LRRK2. Furthermore, LRRK2 enhanced transcriptional activity of NF-κB and cytokine IL-8 production. These findings suggest that LRRK2 might be important in positively modulating IL-1ß-mediated signaling through selective phosphorylation of RCAN1.

Protective effect of the ethanol extract of the roots of Brassica rapa on cisplatin-induced nephrotoxicity in LLC-PK1 cells and rats.

A study was conducted to determine whether the ethanol extract of the roots of Brassica rapa (EBR) ameliorates cisplatin-induced nephrotoxicity in terms of oxidative stress, as characterized by lipid peroxidation, reactive oxygen species (ROS) production, and glutathione (GSH) depletion in LLC-PK1 cells. Pretreatment of cells with EBR prevented cisplatin-induced decreases in cell viability and cellular GSH content. The effect of EBR was then investigated in rats given EBR for 14 d before cisplatin administration. A single dose of cisplatin (7 mg/kg, i.p.) caused kidney damage manifested by an elevation in blood urea nitrogen (BUN), serum creatinine, and urine lactate dehydrogenase (LDH) levels. Also, renal tissue from cisplatin-treated rats showed a significant increase in malondialdehyde (MDA) production, and in the activities of aldehyde oxidase (AO) and xanthine oxidase (XO). Moreover, a significant decrease in the activities of antioxidant enzymes, such as, glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) was observed in cisplatin-treated rats versus saline-treated normal group. In contrast, rats given EBR showed lower blood levels of BUN and creatinine, and of urinary LDH. Moreover, EBR prevented the rise of MDA production and the induction of AO and XO activities. This extract also recovered the reduced activities of GPx, SOD and CAT. Taken together, our data indicate that the ethanol extract of the roots of Brassica rapa (EBR) has a protective effect against cisplatin-induced nephrotoxicity because it attenuates oxidative stress.

Gigantol isolated from the whole plants of Cymbidium goeringii inhibits the LPS-induced iNOS and COX-2 expression via NF-kappaB inactivation in RAW 264.7 macrophages cells.

During our efforts to find bioactive natural products with anti-inflammatory activity, we isolated gigantol from the whole plants of Cymbidium goeringii (Orchidaceae) by activity-guided chromatographic fractionation. Gigantol was found to have potent inhibitory effects on LPS-induced nitric oxide (NO) and prostaglandin E (2) (PGE (2)) production in RAW 264.7 cells. Consistent with these findings, gigantol suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein and mRNA levels in RAW 264.7 cells in a concentration-dependent manner. Our data also indicate that gigantol is a potent inhibitor of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) release and influenced the mRNA expression levels of these cytokines in a dose-dependent manner. Furthermore, a reporter gene assay for nuclear factor kappa B (NF-kappaB) and an electromobility shift assay (EMSA) demonstrated that gigantol effectively inhibited the activation of NF-kappaB, which is necessary for the expression of iNOS, COX-2, TNF-alpha, IL-1beta and IL-6. Thus, our studies suggest that gigantol inhibits LPS-induced iNOS and COX-2 expression by blocking NF- kappaB activation.