Endothelin-1 stimulates leptin production in adipocytes

Leptin is an adipocyte-derived hormone that regulates body fat stores and feeding behavior. In an effort to identify endogenous diffusible modulators of leptin production, we found that endothelin-1 (ET-1) up-regulates leptin expression in adipocytes. ET-1 is as potent and efficacious as insulin in stimulating leptin production in two different adipocyte cell lines. Endothelins stimulate leptin production via the endothelin-A receptor (ET(A)), as judged by a potency rank order of ET-1 ET-3. We detected expression of ET(A) but not ET(B) in both cell lines by Northern blot analysis. In addition, the ET(A)-selective antagonist FR139317 inhibited ET-1-induced leptin expression more potently than did the ET(B)-selective antagonist BQ788. ET-1 and insulin positively interact with each other in increasing leptin production in adipocytes. In primary mouse white fat cells, we detected expression of both ET(A) and ET(B) by Northern blot and in situ hybridization analyses. We conclude that ET-1 stimulates leptin production via the ET(A) receptor in cultured adipocytes.     

Site-specific phosphorylation of tau accompanied by activation of mitogen-activated protein kinase (MAPK) in brains of Niemann-Pick type C mice

Niemann-Pick type C (NPC) disease is characterized by an accumulation of cholesterol in most tissues and progressive neurodegeneration with the formation of neurofibrillary tangles. Neurofibrillary tangles are composed of paired helical filaments (PHF), a major component of which is the hyperphosphorylated tau. In this study we used NPC heterozygous and NPC homozygous mouse brains to investigate the molecular mechanism responsible for tauopathy in NPC. Immunoblot analysis using anti-tau antibodies (Tau-1, PHF-1, AT-180, and AT-100) revealed site-specific phosphorylation of tau at Ser-396 and Ser-404 in the brains of NPC homozygous mice. Mitogen-activated protein kinase, a potential serine kinase known to phosphorylate tau, was activated, whereas other serine kinases such as glycogen synthase kinase-3beta and cyclin-dependent kinase 5 were inactive. Morphological examination demonstrated that a number of neurons, the perikarya of which strongly immunostained with PHF-1, exhibited polymorphorous cytoplasmic inclusion bodies and multi-concentric lamellar-like bodies. Importantly, the accumulation of intracellular cholesterol in NPC mouse brains was determined to be a function of age. From these results we conclude that abnormal cholesterol metabolism due to the genetic mutation in NPC1 may be responsible for activation of the mitogen-activated protein kinase-signaling pathway and site-specific phosphorylation of tau in vivo, leading to tauopathy in NPC.     

Agmatine deiminase from maize shoots: purification and properties

Agmatine deiminase was purified to a specific activity of 537 nkat/mg protein using an improved procedure. The recovery was 47% and the enzyme was homogeneous and remarkably stable. The molecular mass of the enzyme as determined by gel filtration was 75 kDa, and SDS-PAGE suggests that the enzyme is a heterodimer composed of subunits of 43.5 and 44 kDa. The Km for agmatine was 12 microM and arcaine was shown to be a potent competitive inhibitor of the enzyme, with a Ki of 3.3 microM. The enzyme does not have either putrescine synthase activity or the activities of its components ornithine and putrescine transcarbamylase. These results distinctly demonstrate that agmatine deiminase is different from putrescine synthase.     

Accumulation of glycolipids in mutant Chinese hamster ovary cells (Z65) with defective peroxisomal assembly and comparison of the metabolic rate of glycosphingolipids between Z65 cells and wild-type CHO-K1 cells

The influence of peroxisomal dysfunction on glycosphingolipid metabolism was investigated using mutant Chinese hamster ovary (CHO) cells (Z65) with defective assembly of the peroxisomal membranes. In accordance with previous observations, the concentration of very long chain fatty acid (C24:0) was shown to be higher in Z65 cells than in control cells. We then compared the composition of glycolipids in Z65 cells with that in CHO-K1 cells, which are wild-type Chinese hamster ovary cells with intact peroxisomes, and found significantly increased concentrations of ceramide monohexoside (CMH) and ganglioside GM3 in Z65 cells. However, there were no differences in the concentrations of glycerophospholipids, triglycerides, free fatty acids and cholesterol between Z65 and CHO-K1 cells. Further, to investigate the metabolic rate of the major lipids, Z65 and CHO-K1 cells were pulse-labeled with [3-14C]serine. [3-14C]Serine was incorporated into phosphatidylserine, phosphatidylethanolamine and sphingomyelin more quickly in CHO-K1 than in Z65 cells. However, after 48 h, the radioactivity incorporated into those lipids, including CMH, was greater in Z65 cells than in CHO-K1 cells. Thus, the altered metabolism of glycosphingolipids, probably due to peroxisomal dysfunction, was thought to be responsible for the change in glycosphingolipid composition in Z65 cells.     

Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans

Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, suppresses allergic immunoglobulin responses and inflammation caused by polymorphonuclear leukocytes (PMNL) in mice. However, few placebo-controlled clinical trials have examined the efficacy and safety of polyphenolic phytochemicals for treatment of allergic inflammatory diseases in humans. The present study determined whether oral supplementation with rosmarinic acid is an effective intervention for patients with seasonal allergic rhinoconjunctivitis (SAR). In this 21-day, randomized, double-blind, age-matched, placebo-controlled parallel group study, patients with mild SAR were treated daily with extract of Perilla frutescens enriched for rosmarinic acid (200 mg [n=10] or 50 mg [n=9]) or placebo (n=10). Patients recorded symptoms daily in a diary. Profiles of infiltrating cells and concentrations of eotaxin, IL-1beta, IL-8, and histamine were measured in nasal lavage fluid. Serum IgE concentrations and routine blood tests were also examined. As compared with placebo supplementation, supplementation with extract of Perilla frutescens enriched for rosmarinic acid resulted in a significant increase in responder rates for itchy nose, watery eyes, itchy eyes, and total symptoms (P<0.05). Active treatment significantly decreased the numbers of neutrophils and eosinophils in nasal lavage fluid (P<0.05 vs. placebo). Patients reported no adverse events, and no significant abnormalities were detected in routine blood tests. In conclusion, extract of Perilla frutescens enriched for rosmarinic acid can be an effective intervention for mild SAR at least partly through inhibition of PMNL infiltration into the nostrils. Use of this alternative treatment for SAR might reduce treatment costs for allergic diseases.     

Synthesis and biological activity of novel alpha-substituted beta-phenylpropionic acids having pyridin-2-ylphenyl moiety as antihyperglycemic agents

We previously reported the identification of novel oximes having 5-benzyl-2,4-thiazolidinedione with antihyperglycemic activity. We now report the synthesis and biological activity of a novel series of oximes and amides having alpha-substituted-beta-phenylpropionic acids. In this series, we obtained potent PPAR alpha/gamma dual agonist (S)-9d, with which activation of PPAR alpha and PPAR gamma was considerably more potent than that of the reference compounds GW9578 22 and rosiglitazone 3, respectively. This means (S)-9d is of the strongest class of PPAR alpha/gamma dual agonists. In the course of this study, we also obtained 8h, which indicated potent plasma glucose lowering effect in spite of weak PPAR alpha/gamma agonistic activity.