61 research outputs found

    A Potent Inhibitor of SIK2, 3, 3′, 7-Trihydroxy-4′-Methoxyflavon (4′-O-Methylfisetin), Promotes Melanogenesis in B16F10 Melanoma Cells

    Get PDF
    Flavonoids, which are plant polyphenols, are now widely used in supplements and cosmetics. Here, we report that 4′-methylflavonoids are potent inducers of melanogenesis in B16F10 melanoma cells and in mice. We recently identified salt inducible kinase 2 (SIK2) as an inhibitor of melanogenesis via the suppression of the cAMP-response element binding protein (CREB)-specific coactivator 1 (TORC1). Using an in vitro kinase assay targeting SIK2, we identified fisetin as a candidate inhibitor, possibly being capable of promoting melanogenesis. However, fisetin neither inhibited the CREB-inhibitory activity of SIK2 nor promoted melanogenesis in B16F10 melanoma cells. Conversely, mono-methyl-flavonoids, such as diosmetin (4′-O-metlylluteolin), efficiently inhibited SIK2 and promoted melanogenesis in this cell line. The cAMP-CREB system is impaired in Ay/a mice and these mice have yellow hair as a result of pheomelanogenesis, while Sik2+/−; Ay/a mice also have yellow hair, but activate eumelanogenesis when they are exposed to CREB stimulators. Feeding Sik2+/−; Ay/a mice with diets supplemented with fisetin resulted in their hair color changing to brown, and metabolite analysis suggested the presence of mono-methylfisetin in their feces. Thus, we decided to synthesize 4′-O-methylfisetin (4′MF) and found that 4′MF strongly induced melanogenesis in B16F10 melanoma cells, which was accompanied by the nuclear translocation of TORC1, and the 4′-O-methylfisetin-induced melanogenic programs were inhibited by the overexpression of dominant negative TORC1. In conclusion, compounds that modulate SIK2 cascades are helpful to regulate melanogenesis via TORC1 without affecting cAMP levels, and the combined analysis of Sik2+/− mice and metabolites from these mice is an effective strategy to identify beneficial compounds to regulate CREB activity in vivo

    Variants of C-C Motif Chemokine 22 (CCL22) Are Associated with Susceptibility to Atopic Dermatitis: Case-Control Studies

    Get PDF
    Atopic dermatitis (AD) is a common inflammatory skin disease caused by multiple genetic and environmental factors. AD is characterized by the local infiltration of T helper type 2 (Th2) cells. Recent clinical studies have shown important roles of the Th2 chemokines, CCL22 and CCL17 in the pathogenesis of AD. To investigate whether polymorphisms of the CCL22 gene affect the susceptibility to AD, we conducted association studies and functional studies of the related variants. We first resequenced the CCL22 gene and found a total of 39 SNPs. We selected seven tag SNPs in the CCL22 gene, and conducted association studies using two independent Japanese populations (1st population, 916 cases and 1,032 controls; 2nd population 1,034 cases and 1,004 controls). After the association results were combined by inverse variance method, we observed a significant association at rs4359426 (meta-analysis, combined P = 9.6×10−6; OR, 0.74; 95% CI, 0.65–0.85). Functional analysis revealed that the risk allele of rs4359426 contributed to higher expression levels of CCL22 mRNA. We further examined the allelic differences in the binding of nuclear proteins by electrophoretic mobility shift assay. The signal intensity of the DNA-protein complex derived from the G allele of rs223821, which was in absolute LD with rs4359426, was higher than that from the A allele. Although further functional analyses are needed, it is likely that related variants play a role in susceptibility to AD in a gain-of-function manner. Our findings provide a new insight into the etiology and pathogenesis of AD

    Involvement of SIK3 in Glucose and Lipid Homeostasis in Mice

    Get PDF
    Salt-inducible kinase 3 (SIK3), an AMP-activated protein kinase-related kinase, is induced in the murine liver after the consumption of a diet rich in fat, sucrose, and cholesterol. To examine whether SIK3 can modulate glucose and lipid metabolism in the liver, we analyzed phenotypes of SIK3-deficent mice. Sik3−/− mice have a malnourished the phenotype (i.e., lipodystrophy, hypolipidemia, hypoglycemia, and hyper-insulin sensitivity) accompanied by cholestasis and cholelithiasis. The hypoglycemic and hyper-insulin-sensitive phenotypes may be due to reduced energy storage, which is represented by the low expression levels of mRNA for components of the fatty acid synthesis pathways in the liver. The biliary disorders in Sik3−/− mice are associated with the dysregulation of gene expression programs that respond to nutritional stresses and are probably regulated by nuclear receptors. Retinoic acid plays a role in cholesterol and bile acid homeostasis, wheras ALDH1a which produces retinoic acid, is expressed at low levels in Sik3−/− mice. Lipid metabolism disorders in Sik3−/− mice are ameliorated by the treatment with 9-cis-retinoic acid. In conclusion, SIK3 is a novel energy regulator that modulates cholesterol and bile acid metabolism by coupling with retinoid metabolism, and may alter the size of energy storage in mice

    Evaluation of miR-122 to Predict High Dose Acetaminophen-Induced Liver Injury in Mice: The Combination Uses of 5-Fluorouracil

    Get PDF
    Administration of high doses of acetaminophen (APAP) is known to cause drug-induced liver injury (DILI) in humans. Therefore, the detection or prediction of these side-effects at an early stage using appropriate biomarkers is the need of the hour. Micro RNA (miR)-122 is expected to be a novel biomarker for liver injury. However, more evidence is required in various alternate situations such as its use in combination as APAP is often used along with anticancer drugs. In the present study, we aimed to evaluate the functions of miR-122 as a biomarker for liver injury in comparison with alanine aminotransferase (ALT) in a mice model with the APAP-induced liver injury (AILI). Consequently, there was a dose-dependent increase in miR-122 after administration of APAP intraperitoneally. Similar observations were made for ALT activity. Additionally, the expression of miR-122 increased in a more rapid manner compared to ALT activity. However, there was a variation in the miR-122 expression. Further, we investigated the drug-drug interaction between APAP and 5-fluorouracil using miR-122 and ALT in mice. As a result, the degree of AILI was not changed by the use of 5-fluorouracil in combination with APAP in mice
    corecore