Oxidized low density lipoprotein activates peroxisome proliferator-activated receptor-alpha (PPARalpha) and PPARgamma through MAPK-dependent COX-2 expression in macrophages

It has been reported that oxidized low density lipoprotein (Ox-LDL) can activate both peroxisome proliferator-activated receptor-alpha (PPARalpha) and PPARgamma. However, the detailed mechanisms of Ox-LDL-induced PPARalpha and PPARgamma activation are not fully understood. In the present study, we investigated the effect of Ox-LDL on PPARalpha and PPARgamma activation in macrophages. Ox-LDL, but not LDL, induced PPARalpha and PPARgamma activation in a dose-dependent manner. Ox-LDL transiently induced cyclooxygenase-2 (COX-2) mRNA and protein expression, and COX-2 specific inhibition by NS-398 or meloxicam or small interference RNA of COX-2 suppressed Ox-LDL-induced PPARalpha and PPARgamma activation. Ox-LDL induced phosphorylation of ERK1/2 and p38 MAPK, and ERK1/2 specific inhibition abrogated Ox-LDL-induced COX-2 expression and PPARalpha and PPARgamma activation, whereas p38 MAPK-specific inhibition had no effect. Ox-LDL decreased the amounts of intracellular long chain fatty acids, such as arachidonic, linoleic, oleic, and docosahexaenoic acids. On the other hand, Ox-LDL increased intracellular 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) level through ERK1/2-dependent overexpression of COX-2. Moreover, 15d-PGJ(2) induced both PPARalpha and PPARgamma activation. Furthermore, COX-2 and 15d-PGJ(2) expression and PPAR activity were increased in atherosclerotic lesions of apoE-deficient mice. Finally, we investigated the involvement of PPARalpha and PPARgamma on Ox-LDL-induced mRNA expression of ATP-binding cassette transporter A1 and monocyte chemoattractant protein-1. Interestingly, specific inhibition of PPARalpha and PPARgamma suppressed Ox-LDL-induced ATP-binding cassette transporter A1 mRNA expression and enhanced Ox-LDL-induced monocyte chemoattractant protein-1 mRNA expression. In conclusion, Ox-LDL-induced increase in 15d-PGJ(2) level through ERK1/2-dependent COX-2 expression is one of the mechanisms of PPARalpha and PPARgamma activation in macrophages. These effects of Ox-LDL may control excess atherosclerotic progression.     

Rabbit antibody detection with RNA aptamers

Antibody-based detection systems are widely used, but in the cases of immunoprecipitations and enzyme-linked immunoassays, they can be laborious. These techniques require the preparation of at least two kinds of non-cross-reactive immunoglobulin Gs (IgGs), usually made from different species against the single target molecule. Aptamers composed of nucleic acids possess strict recognition ability for the target molecule's three-dimensional structure and, thus, are considered to act like IgG. In this study, experimental trials were designed to combine the advantages of IgG and aptamers. For this purpose, aptamers against rabbit IgG were identified by in vitro selection. One of the obtained aptamers had a dissociation constant lower than 15 pM to the rabbit IgG. It bound specifically to the constant region of the rabbit IgG, and no binding was observed with mouse or goat IgG. Moreover, this aptamer recognized only the native form of rabbit IgG and could not bind the sodium dodecyl sulfate (SDS)-denatured form. These features show the advantage of using the aptamer as a secondary probing agent rather than the usual secondary antibodies.     

Cytologic features of chordoid meningioma. A case report

BACKGROUND: Chordoid meningioma is a rare subtype of meningioma characterized by myxoid matrices deposited among epithelioid or vacuolated tumor cells and infiltrates of inflammatory cells, and its cytologic features have rarely been reported. CASE: A 57-year-old man with a history of headache and visual disturbance presented with a tumor in the suprasellar region. Intraoperative touch smear cytology of the tumor disclosed a cord-like arrangement of polygonal tumor cells occasionally containing intranuclear inclusions. Furthermore, periodic acid-Schiff-positive, mucinous matrices were deposited among the tumor cells. Also, infiltrates of lymphocytes and plasma cells were noted. Histologic, immunohistochemical and ultrastructural examination confirmed the diagnosis of chordoid meningioma. CONCLUSION: Intraoperative smear cytology in a case of chordoid meningioma showed distinctive cytologic features suggestive of the histologic patterns. The cytologic features, together with a histologic examination, are useful for its diagnosis.     

Concentrations of essential elements after repeated administrations of tin and selenium

To study effects of simultaneous administration of tin (Sn) and selenium (Se) on concentrations of several essential elements, mice were injected with either SnCl2 (ip) or Na2SeO3 (sc), alone or both compounds at a daily dose of 5 mumol/kg each for 12 consecutive days. Mice were sacrificed at 20 h after the last injection and concentrations of Sn, Se, Na, Ca, Zn, P, Fe, K, and Mg in the liver, kidney, spleen, pancreas, testis, seminal vesicle, lung, femoral muscle, and femoral bone were determined. In the control mice, Sn and Se concentrations were the highest in bone (0.69 micrograms Sn and 6.93 micrograms Se/g dry wt). Administered Sn was found to accumulate in all organs except the testis. Among the essential elements determined, Na was the most affected in terms of concentration in the organs and Mg was the least affected element in these organs. Among the organs tested, each elemental concentration in the pancreas was most affected. Simultaneous injections of Sn and Se appeared to keep the correlation coefficients between elements similar to those found in the control mice.     

Fucoxanthin promotes translocation and induction of glucose transporter 4 in skeletal muscles of diabetic/obese KK-A(y) mice

Fucoxanthin (Fx) isolated from Undaria pinnatifida suppresses the development of hyperglycemia and hyperinsulinemia of diabetic/obese KK-A(y) mice after 2 weeks of feeding 0.2% Fx-containing diet. In the soleus muscle of KK-A(y) mice that were fed Fx, glucose transporter 4 (GLUT4) translocation to plasma membranes from cytosol was promoted. On the other hand, Fx increased GLUT4 expression levels in the extensor digitorum longus (EDL) muscle, although GLUT4 translocation tended to increase. The expression levels of insulin receptor (IR) mRNA and phosphorylation of Akt, which are in upstream of the insulin signaling pathway regulating GLUT4 translocation, were also enhanced in the soleus and EDL muscles of the mice fed Fx. Furthermore, Fx induced peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α), which has been reported to increase GLUT4 expression, in both soleus and EDL muscles. These results suggest that in diabetic/obese KK-A(y) mice, Fx improves hyperglycemia by activating the insulin signaling pathway, including GLUT4 translocation, and inducing GLUT4 expression in the soleus and EDL muscles, respectively, of diabetic/obese KK-A(y) mice.     

Effect of phenformin on the response of plasma intestinal glucagon-like immunoreactivity (GLI) to oral glucose in gastrectomized subjects.

The effect of phenformin (DBI) on the plasma intestinal glucagon-like immunoreactivity (GLI) and pancreatic glucagon (IRG) responses to oral and intravenous glucose loads were studied in 26 gastrectomized subjects, using a cross-reacting and an IRG-specific anti-serum. The drug produced no significant changes in fasting GLI and IRG levels. Thirty minutes after oral glucose alone, the total GLI level rose to a peak of 1.55 +/- 0.17 ng/ml in the untreated subjects and to a maximum level of 1.67 +/- 0.18 ng/ml in the DBI-pretreated subjects. However, the mean GLI levels obtained 120 and 180 min after oral glucose were significantly higher after treatment with DBI. The blood sugar and IRI responses to oral glucose were lowered significantly by DBI pretreatment. DBI did not alter the glucose, IRI, IRG and GLI response to intravenous glucose. These results suggest that the release of intestinal GLI is not related to the intestinal absorption of glucose.     

Adaptive Responses Limited by Intrinsic Noise

Sensory systems have mechanisms to respond to the external environment and adapt to them. Such adaptive responses are effective for a wide dynamic range of sensing and perception of temporal change in stimulus. However, noise generated by the adaptation system itself as well as extrinsic noise in sensory inputs may impose a limit on the ability of adaptation systems. The relation between response and noise is well understood for equilibrium systems in the form of fluctuation response relation. However, the relation for nonequilibrium systems, including adaptive systems, are poorly understood. Here, we systematically explore such a relation between response and fluctuation in adaptation systems. We study the two network motifs, incoherent feedforward loops (iFFL) and negative feedback loops (nFBL), that can achieve perfect adaptation. We find that the response magnitude in adaption systems is limited by its intrinsic noise, implying that higher response would have higher noise component as well. Comparing the relation of response and noise in iFFL and nFBL, we show that whereas iFFL exhibits adaptation over a wider parameter range, nFBL offers higher response to noise ratio than iFFL. We also identify the condition that yields the upper limit of response for both network motifs. These results may explain the reason of why nFBL seems to be more abundant in nature for the implementation of adaption systems.     

Novel recognition sequence of coxsackievirus 2A proteinase

Coxsackievirus B1 (CVB1) 2A proteinase (2A(pro)) is a cysteine proteinase that cleaves the viral monocistronic polyprotein between the C-terminus of the VP1 region and the N-terminus of the 2A region, and also shuts off translational initiation in host cells by cleavage of eukaryotic initiation factor 4G (eIF4G) isoforms. We expressed in Escherichia coli a series of fusions in which various C-terminal fragments of VP1 were linked to the N-terminus of 2A(pro), and we also employed site-directed mutagenesis to introduce mutations of several amino acid residues. Our results showed that the presence of the C-terminal three amino acid residues of VP1 at the N-terminus of 2A(pro) is sufficient for specific self-cleavage between VP1 and 2A(pro) to generate mature 2A(pro), but the P4 amino acid also plays an important role. We further found that 2A(pro) cleaves the amino acid sequence Leu-Val-Pro-Arg-( *)Gly-Ser (LVPRGS motif), which is the target sequence of thrombin.     

Protein kinase C modulates in vitro phosphorylation of the smooth muscle heavy meromyosin by myosin light chain kinase

Protein kinase C phosphorylates different sites on the 20,000-Da light chain of smooth muscle heavy meromyosin (HMM) than did myosin light chain kinase (Nishikawa, M., Hidaka, H., and Adelstein, R. S. (1983) J. Biol. Chem. 258, 14069-14072). Although protein kinase C incorporates 1 mol of phosphate into 1 mol of 20,000-Da light chain when either HMM or the whole myosin molecule is used as a substrate, it catalyzes the incorporation of up to 3 mol of phosphate/mol of 20,000-Da light chain when the isolated light chains are used as a substrate. Threonine is the major phosphoamino acid resulting from phosphorylation of HMM by protein kinase C. Prephosphorylation of HMM by protein kinase C decreases the rate of phosphorylation of HMM by myosin light chain kinase due to a 9-fold increase of the Km for prephosphorylated HMM compared to that of unphosphorylated HMM. Prephosphorylation of HMM by myosin light chain kinase also results in a decrease of the rate of phosphorylation by protein kinase C due to a 2-fold increase of the Km for HMM. Both prephosphorylations have little or no effect on the maximum rate of phosphorylation. The sequential phosphorylation of HMM by myosin light chain kinase and protein kinase C results in a decrease in actin-activated MgATPase activity due to a 7-fold increase of the Km for actin over that observed with phosphorylated HMM by myosin light chain kinase but has little effect on the maximum rate of the actin-activated MgATPase activity. The decrease of the actin-activated MgATPase activity correlates well with the extent of the additional phosphorylation of HMM by protein kinase C following initial phosphorylation by myosin light chain kinase.     

Stabilization of E. coli Ribonuclease HI by the 'stability profile of mutant protein' (SPMP)-inspired random and non-random mutagenesis

The change in the structural stability of Escherichia coli ribonuclease HI (RNase HI) due to single amino acid substitutions has been estimated computationally by the stability profile of mutant protein (SPMP) [Ota, M., Kanaya, S. Nishikawa, K., 1995. Desk-top analysis of the structural stability of various point mutations introduced into ribonuclease H. J. Mol. Biol. 248, 733-738]. As well, an effective strategy using random mutagenesis and genetic selection has been developed to obtain E. coli RNase HI mutants with enhanced thermostability [Haruki, M., Noguchi, E., Akasako, A., Oobatake, M., Itaya, M., Kanaya, S., 1994. A novel strategy for stabilization of Escherichia coli ribonuclease HI involving a screen for an intragenic suppressor of carboxyl-terminal deletions. J. Biol. Chem. 269, 26904-26911]. In this study, both methods were combined: random mutations were individually introduced to Lys99-Val101 on the N-terminus of the alpha-helix IV and the preceding beta-turn, where substitutions of other amino acid residues were expected to significantly increase the stability from SPMP, and then followed by genetic selection. Val101 to Ala, Gln, and Arg mutations were selected by genetic selection. The Val101-->Ala mutation increased the thermal stability of E. coli RNase HI by 2.0 degrees C in Tm at pH 5.5, whereas the Val101-->Gln and Val101-->Arg mutations decreased the thermostability. Separately, the Lys99-->Pro and Asn100-->Gly mutations were also introduced directly. The Lys99-->Pro mutation increased the thermostability of E. coli RNase HI by 1.8 degrees C in Tm at pH 5.5, whereas the Asn100-->Gly mutation decreased the thermostability by 17 degrees C. In addition, the Lys99-->Pro mutation altered the dependence of the enzymatic activity on divalent metal ions.