Biomedical subjects

Masayuki Saito

Publications and source records attributed to Masayuki Saito.

At least 19 recordsLinked to original sources

PubMed2006

Brown fat UCP1 is not involved in the febrile and thermogenic responses to IL-1beta in mice.

The activity of brown adipose tissue (BAT), a site of nonshivering metabolic thermogenesis, has been reported to increase after interleukin (IL)-1beta/lipopolysaccharide injection. To clarify the possible contribution of BAT thermogenesis to whole body febrile response, we investigated febrile and thermogenic response to IL-1beta using mice deficient in uncoupling protein-1 (UCP1), a key molecule for BAT thermogenesis. In wild-type (WT) mice, IL-1beta injection (5 microg/kg ip) increased body temperature (+1.82 degrees C at 20 min), decreased physical activity (-37% at 1 h), and produced a slight and insignificant rise (+15% at 1 h) in oxygen consumption (Vo(2)). Vo(2) dependent on metabolic thermogenesis (DeltaVO2 thermogenesis) calculated by correcting the effect of physical activity was increased after IL-1beta injection (726 +/- 200 ml x h(-1) x kg(-1) at 1 h). Almost the same responses were observed in UCP1-deficient mice, showing 638 +/- 87 ml x h(-1) x kg(-1) of DeltaVO2 thermogenesis at 1 h. In contrast, CL316,243, a selective activator of BAT thermogenesis, increased body temperature, decreased physical activity, and produced a significant rise in Vo2 in WT mice, showing 1,229 +/- 35 ml x h(-1) x kg(-1) of DeltaVO2 thermogenesis at 1 h. These changes were not observed in UCP1-deficient mice. These results, conflicting with a previously proposed idea of a role of BAT in fever, suggest a minor contribution of BAT thermogenesis to IL-1beta-induced fever. In support of this, we found no effect of IL-1beta on triglyceride content and UCP1 mRNA level in BAT, in contrast with apparent effects of CL316,243.

Adipose Tissue, Brown↗

PubMed2006

Inverse regulation of leptin mRNA expression by short- and long-chain fatty acids in cultured bovine adipocytes.

Leptin is an adipose tissue-derived cytokine plays key roles in the regulation of food intake and energy expenditure. However, regulatory mechanisms of leptin gene expression are not fully elucidated in ruminants that utilize short-chain fatty acids (SCFA), known as volatile fatty acids, as principal energy sources. In this study, we determined effects of SCFA and long-chain fatty acids (LCFA) on leptin expression in bovine adipocytes. Bovine stromal vascular cells isolated from subcutaneous adipose tissue of Holstein cows were cultured to confluence and treated sequentially with dexamethasone and isobutylmethylxanthine for 2 days and insulin and troglitazone for 12 days to achieve full differentiation to adipocytes. The cells started to accumulate lipids 4 days after the onset of treatment, with increased mRNA expression of leptin, as well as aP2, adiponectin, and PPAR-gamma. Removal of fetal calf serum and reduction of glucose in the culture medium of differentiated adipocytes decreased leptin mRNA expression. Subsequent addition of acetate, butyrate, or propionate dose-dependently restored and rather increased leptin expression, while addition of LCFA suppressed it. The stimulatory effect of acetate was abolished by prior treatment of the cells with pertussis toxin and by addition of LCFA. Furthermore, cows fasted for 48h and fed thereafter, elaborate reduced and increased plasma leptin levels, respectively. Thus, these results suggest that plasma leptin levels in cows are inversely controlled at the transcription level by VFA and LCFA, and that the effects of SCFA possibly act through a G protein-coupled receptor for SCFA.

1-Methyl-3-isobutylxanthine↗

PubMed2006

Formation of two methylenedioxy bridges by a Sesamum CYP81Q protein yielding a furofuran lignan, (+)-sesamin.

(+)-Sesamin, a furofuran class lignan, is widespread in vascular plants and represented by Sesamum spp. (+)-Sesamin has been of rapidly growing interest because of its beneficial biological effects in mammals, but its biosynthesis and physiological roles in plants remain to be clarified. It is speculated to be synthesized from (+)-pinoresinol by means of (+)-piperitol by formation of two methylenedioxy bridges mediated by two distinct Sesamum indicum cytochrome P450 (SiP450) proteins. Here, we report an SiP450, CYP81Q1, that alone catalyzes (+)-sesamin biosynthesis from (+)-pinoresinol by means of (+)-piperitol by forming two methylenedioxy bridges. The CYP81Q1 gene expression profile was temporally consistent with the accumulation pattern of (+)-sesamin during seed development. The CYP81Q1-GFP chimera protein was colocalized with an endoplasmic reticulum (ER)-targeting chimera protein, indicating that (+)-sesamin biosynthesis occurs on the ER cytoplasmic surface. Moreover, we isolated two CYP81Q1 homologs from other Sesamum spp. Sesamum radiatum CYP81Q2 showed dual (+)-piperitol/(+)-sesamin synthetic activity. CYP81Q2, as well as CYP81Q1, therefore, corresponds to a (+)-piperitol/(+)-sesamin synthase in lignan biosynthesis. In contrast, Sesamum alatum CYP81Q3 showed no activity, in accord with (+)-sesamin being deficient in S. alatum. Our findings not only provide insight into lignan biosynthesis but also unravel a unique mode of cytochrome P450 action.

Amino Acid Sequence↗

PubMed2006

Potential contribution of vasoconstriction to suppression of heat loss and homeothermic regulation in UCP1-deficient mice.

To investigate the thermoregulatory mechanism in mice lacking uncoupling protein 1 (UCP1) from the viewpoint of heat loss, we measured oxygen consumptions (VO2), skin-surface temperatures (Tskin, an index of heat release), blood flows in the tails, and rectal temperatures (Trectal) of mice housed in an animal room under the standard thermal condition of approximately 23 degrees C. Compared with wild-type (Ucp1+/+) mice, adult UCP1-deficient (Ucp1-/-) mice tended to show a reduced VO2. Thermograhic analysis of the acute response of Ucp1-/- mice to a small change (a drop of 1-2 degrees C) in the ambient temperature revealed a sustained fall in the Tskin of Ucp1-/- mice; but this fall was only transient in Ucp1+/+ mice. Analysis of tail blood flow under anesthesia clearly showed a stronger vasoconstrictor response in Ucp1-/- mice than in Ucp1+/+ mice. Administration of a vasodilator, evodiamine, transiently increased Tskin in Ucp1+/+ and Ucp1-/- mice similarly; whereas the induction of vasodilation caused a greater and more prolonged reduction in Trectal in Ucp1-/- mice than in Ucp1+/+ mice. These results indicate that Ucp1-/- mice highly, or at least partly, rely on vasoconstriction for heat conservation to compensate for their UCP1 deficiency and to maintain homeothermy under the condition of normal housing temperature.

Animals↗

PubMed2006

Postprandial changes in leptin concentrations of cerebrospinal fluid in dogs during development of obesity.

OBJECTIVE: To evaluate postprandial changes in the leptin concentration of CSF in dogs during development of obesity. ANIMALS: 4 male Beagles. PROCEDURES: Weight gain was induced and assessments were made when the dogs were in thin, optimal, and obese body conditions (BCs). The fat area at the level of the L3 vertebra was measured via computed tomography to assess the degree of obesity. Dogs were evaluated in fed and unfed states. Dogs in the fed state received food at 9 AM. Blood and CSF samples were collected at 8 AM, 4 PM, and 10 PM. RESULTS: Baseline CSF leptin concentrations in the thin, optimal, and obese dogs were 24.3 +/- 2.7 pg/mL, 86.1 +/- 14.7 pg/mL, and 116.2 +/- 47.3 pg/mL, respectively. In the thin BC, CSF leptin concentration transiently increased at 4 PM. In the optimal BC, baseline CSF leptin concentration was maintained until 10 PM. In the obese BC, CSF leptin concentration increased from baseline value at 4 PM and 10 PM. Correlation between CSF leptin concentration and fat area was good at all time points. There was a significant negative correlation between the CSF leptin concentration-to-serum leptin concentration ratio and fat area at 4 PM; this correlation was not significant at 8 AM and 10 PM. CONCLUSIONS AND CLINICAL RELEVANCE: Decreased transport of leptin at the blood-brain barrier may be 1 mechanism of leptin resistance in dogs. However, leptin resistance at the blood-brain barrier may not be important in development of obesity in dogs.

Animals↗

PubMed2006

Effects of administration of glucocorticoids and feeding status on plasma leptin concentrations in dogs.

OBJECTIVE: To investigate effects of short- and long- term administration of glucocorticoids, feeding status, and serum concentrations of insulin and cortisol on plasma leptin concentrations in dogs. ANIMALS: 20 nonobese dogs. PROCEDURE: For experiment 1, plasma leptin concentrations and serum concentrations of insulin and cortisol were monitored for 24 hours in 4 dogs administered dexamethasone (0.1 mg/kg, IV) or saline (0.9% NaCl) solution for fed and nonfed conditions. For experiment 2, 11 dogs were administered prednisolone (1 mg/kg, PO, q 24 h for 56 days [7 dogs] and 2 mg/kg, PO, q 24 h for 28 days [4 dogs]) and 5 dogs served as control dogs. Plasma leptin and serum insulin concentrations were monitored weekly. RESULTS: For experiment 1, dexamethasone injection with the fed condition drastically increased plasma leptin concentrations. Furthermore, injection of saline solution with the fed condition increased plasma leptin concentrations. These increases in plasma leptin concentrations correlated with increases in serum insulin concentrations. Dexamethasone injection with the nonfed condition increased plasma leptin concentrations slightly but continuously. Injection of saline solution with the nonfed condition did not alter plasma leptin concentrations. For experiment 2, prednisolone administration at either dosage and duration did not alter plasma leptin concentrations in any dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Dexamethasone injection and feeding increased plasma leptin concentrations in dogs. In addition, dexamethasone administration enhanced the effect of feeding on increases in plasma leptin concentrations. Daily oral administration of prednisolone (1 or 2 mg/kg) did not affect plasma leptin concentrations in dogs.

Animals↗

PubMed2006

[Long-term results after recurrence of completely resected primary lung cancer].

The recurrence rate of complete surgical resection and the long-term results following recurrence have rarely been reported. Whether patients with recurrence could be cured is still unknown. Patients who underwent complete surgical resection for lung cancer from 1981 to 1999 (n=945) and were followed-up for more than 5 years were retrospectively reviewed. Recurrent diseases were treated by chemotherapy and/or radiotherapy when surgical treatment was not indicated. Postoperative 5-year survival in 585 patients (62%) without recurrence and in 360 patients (38%) with recurrent diseases were 84 and 27%, respectively. The recurrence rates of stage I patients (n=164), stage II (n=55), stage III (n=127) and stage IV (n=13) were 26, 52, 68 and 93%, respectively. The 5-year survival rates of these patients were 36, 23, 19 and 7%, respectively. The period between the operation and the first recurrence was approximately 2 (0-9) years and the patients with recurrence died in about 1 (0-9) year. Four patients actually survived more than 10 years after the first recurrence. The recurrence rate after complete surgical resection of lung cancer was 38% in all and it increased along with the advanced pathological stages.

Adult↗

PubMed2005

Indispensable role of mitochondrial UCP1 for antiobesity effect of beta3-adrenergic stimulation.

Mitochondrial uncoupling protein-1 (UCP1) has been thought to be a key molecule for thermogenesis during cold exposure and spontaneous hyperphagia and thereby in the autonomic regulation of energy expenditure and adiposity. However, UCP1 knockout (KO) mice were reported to be cold intolerant but unexpectedly did not get obese even after hyperphagia, implying that UCP1 may not be involved in the regulation of adiposity. Treatment of obese animals with beta3-adrenergic agonists is known to increase lipid mobilization, induce UCP1, and, finally, reduce body fat content. To obtain direct evidence for the role of UCP1 in the anti-obesity effect of beta3-adrenergic stimulation, in the present study, UCP1-KO and wild-type (WT) mice were fed on cafeteria diets for 8 wk and then given a beta3-adrenergic agonist, CL-316,243 (CL), or saline for 2 wk. A single injection of CL increased whole body oxygen consumption and brown fat temperature in WT mice but not in KO mice, and it elicited almost the same plasma free fatty acid response in WT and KO mice. WT and KO mice increased similarly their body and white fat pad weights on cafeteria diets compared with those on laboratory chow. Daily treatment with CL resulted in a marked reduction of white fat pad weight and the size of adipocytes in WT mice, but not in KO mice. Compared with WT mice, KO mice expressed increased levels of UCP2 in brown fat but decreased levels in white fat and comparable levels of UCP3. It was concluded that the anti-obesity effect of beta3-adrenergic stimulation is largely attributable to UCP1, but less to UCP2 and UCP3, and thereby to UCP1-dependent degradation of fatty acids released from white adipose tissue.

Adipose Tissue↗

PubMed2005

Elevated plasma concentrations of haptoglobin in European brown bears during hibernation.

Haptoglobin (Hp), a hemoglobin-binding protein, is known as an acute phase protein and increases during the acute phase of inflammation in most mammals. We reported previously in brown bears that the mean Hp concentrations were higher in blood samples obtained in winter than those in spring. To examine a possible relation of the seasonal variations of Hp to hibernation, in the present study, we measured the plasma concentrations of Hp as well as some other acute phase proteins (alpha(2)-macroglobulin, alpha(1)-antitrypsin, C-reactive protein) in 6 European brown bears (Ursus arctos), from which blood samples were obtained at 5-6 different months of year including February, the time of hibernation. The Hp concentrations showed clear seasonal variations, being highest in February. The alpha(2)-macroglobulin concentrations also showed a similar but much smaller rise in February, but those of alpha(1)-antitrypsin and C-reactive protein did not show any seasonal variations. Our results suggest that the seasonal variation of plasma Hp concentration in brown bears is associated with a hibernation-specific mechanism more than that of acute phase response.

Animals↗

PubMed2005

Bovine hepatocyte growth factor and its receptor c-Met: cDNA cloning and expression analysis in the mammary gland.

Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic cytokine that plays a crucial role in the embryonic and postnatal development of various organs including the mammary gland. We cloned bovine HGF and its c-Met receptor cDNAs, and examined their expression during mammary gland development in dairy cows. The 2.5-kbp HGF cDNA clone contained a 2190 bp open reading frame coding a 730 amino acid protein, while the 4.8-kbp c-Met cDNA clone contained a 4152 bp open reading frame coding a 1384 amino acid protein. The bovine HGF and c-Met sequences exhibited more than 87% identity with those of other mammals. RT-PCR analysis revealed ubiquitous expression of both HGF and c-Met mRNAs in various bovine tissues tested. HGF mRNA was detected only in the inactive stage of bovine mammary gland development and not in the developing, lactating, and involuting stages, while c-Met mRNA was detected in the inactive and involuting stages. Immunohistochemical analysis demonstrated that the c-Met protein was found on mammary epithelial cells in the inactive, developing, and involuting stages, and on myoepithelial cells in all stages. These results suggest pivotal roles of HGF and c-Met in the development of bovine mammary gland.

Animals↗

PubMed2005

Seasonal changes in serum leptin of the feral raccoon (Procyon lotor) determined by canine-leptin-specific ELISA.

Several reports have been published on blood leptin concentrations in feral animals, including members of the Carnivora, using a commercially available multi-species radioimmunoassay (RIA) kit with anti-human leptin antibody. However, we observed weak immunoreactivity between recombinant canine leptin and anti-human leptin antibody, suggesting a limitation in the applicability of the RIA kit for leptin assays in Carnivora species. We tested the applicability of RIA and sandwich enzyme-linked immunosorbent assay (ELISA) with anti-canine leptin antibody to assay blood leptin in the dog (Canis familiaris) and the raccoon (Procyon lotor). When RIA was used for recombinant canine leptin and dog sera, values were much lower than those determined by ELISA at higher concentrations (>10 ng/ml), while rather higher at lower concentrations (<2 ng/ml). A similar discrepancy between the two methods was found for serum leptin concentrations in raccoons. Clear seasonal variations were observed by ELISA, but not by RIA, with high values in autumn (3.46+/-0.45 ng/ml) and low values in spring and summer (0.71+/-0.07 ng/ml). Serum leptin concentrations in raccoons correlated positively with their body weight (r=0.753) and body mass index (r=0.755), corroborating our previous findings of a strong positive correlation between serum leptin concentrations and body fat content in dogs. Thus, the canine leptin ELISA is useful for assays of dog and raccoon leptin, and blood leptin is a good marker of nutritional condition in the species of Carnivora assayed in this study.

Animals↗

PubMed2005

Leptin resistance extends to the coronary vasculature in prediabetic dogs and provides a protective adaptation against endothelial dysfunction.

Hyperleptinemia, associated with prediabetes, is an independent risk factor for coronary artery disease and a mediator of coronary endothelial dysfunction. We previously demonstrated that acutely raising the leptin concentration to levels comparable with those observed in human obesity significantly attenuates coronary dilation/relaxation to acetylcholine (ACh) both in vivo in anesthetized dogs and in vitro in isolated canine coronary rings. Accordingly, the purpose of this investigation was to extend these studies to a model of prediabetes with chronic hyperleptinemia. In the present investigation, experiments were conducted on control and high-fat-fed dogs. High-fat feeding caused a significant increase (131%) in plasma leptin concentration. Furthermore, in high-fat-fed dogs, exogenous leptin did not significantly alter vascular responses to ACh in vivo or in vitro. Coronary vasodilator responses to ACh (0.3-30.0 microg/min) and sodium nitroprusside (1.0-100.0 microg/min) were not significantly different from those observed in control dogs. Also, high-fat feeding did not induce a switch to an endothelium-derived hyperpolarizing factor as a major mediator of muscarinic coronary vasodilation, because dilation to ACh was abolished by combined pretreatment with N(omega)-nitro-l-arginine methyl ester (150 microg/min ic) and indomethacin (10 mg/kg iv). Quantitative, real-time PCR revealed no significant difference in coronary artery leptin receptor gene expression between control and high-fat-fed dogs. In conclusion, high-fat feeding induces resistance to the coronary vascular effects of leptin, and this represents an early protective adaptation against endothelial dysfunction. The resistance is not due to altered endothelium-dependent or -independent coronary dilation, increased endothelium-derived hyperpolarizing factor, or changes in coronary leptin receptor mRNA levels.

Adaptation, Physiological↗

PubMed2005

Portal 5-hydroxytryptophan infusion enhances glucose disposal in conscious dogs.

Intraportal serotonin infusion enhances net hepatic glucose uptake (NHGU) during glucose infusion but blunts nonhepatic glucose uptake and can cause gastrointestinal discomfort and diarrhea at high doses. Whether the serotonin precursor 5-hydroxytryptophan (5-HTP) could enhance NHGU without gastrointestinal side effects during glucose infusion was examined in conscious 42-h-fasted dogs, using arteriovenous difference and tracer ([3-3H]glucose) techniques. Experiments consisted of equilibration (-120 to -30 min), basal (-30 to 0 min), and experimental (EXP; 0-270 min) periods. During EXP, somatostatin, fourfold basal intraportal insulin, basal intraportal glucagon, and peripheral glucose (to double the hepatic glucose load) were infused. In one group of dogs (HTP, n = 6), saline was infused intraportally from 0 to 90 min (P1), and 5-HTP was infused intraportally at 10, 20, and 40 microg x kg(-1) x min(-1) from 90 to 150 (P2), 150 to 210 (P3), and 210 to 270 (P4) min, respectively. In the other group (SAL, n = 7), saline was infused intraportally from 0 to 270 min. NHGU in SAL was 14.8 +/- 1.9, 18.5 +/- 2.3, 16.3 +/- 1.4, and 19.7 +/- 1.6 micromol x kg(-1) x min(-1) in P1-P4, whereas NHGU in 5-HTP averaged 16.4 +/- 2.6, 18.5 +/- 1.4, 20.8 +/- 2.0, and 27.6 +/- 2.6 micromol x kg(-1) x min(-1) (P < 0.05 vs. SAL). Nonhepatic glucose uptake (micromol x kg(-1) x min(-1)) in SAL was 30.2 +/- 4.3, 36.8 +/- 5.8, 44.3 +/- 5.8, and 54.6 +/- 11.8 during P1-P4, respectively, whereas in HTP the corresponding values were 26.3 +/- 6.8, 44.9 +/- 10.1, 47.5 +/- 11.7, and 51.4 +/- 13.2 (not significant between groups). Intraportal 5-HTP enhances NHGU without significantly altering nonhepatic glucose uptake or causing gastrointestinal side effects, raising the possibility that a related agent might have a role in reducing postprandial hyperglycemia.

5-Hydroxytryptophan↗

PubMed2005

Effects of chronic obesity and weight loss on plasma ghrelin and leptin concentrations in dogs.

The objective of this study was to evaluate, in dogs, the effects of obesity and weight loss on plasma total ghrelin and leptin concentrations. Twenty-four Beagle dogs, 12 control lean and 12 obese dogs of both genders and aged between 1 and 9 years, were used for the experiments. Mean body weight was 12.7+/-0.7 kg for the lean group and 21.9+/-0.8 kg for the obese group. The trial was divided into three phases. During phase 1, all 24 Beagle dogs were fed a maintenance diet. During phase 2, the obese dogs were submitted to a weight loss protocol with a high protein-low energy diet. The weight loss protocol ended once dogs reached optimal body weight. During phase 3, the dogs that were submitted to the weight loss protocol were maintained at their optimal body weight for 6 months. Plasma total ghrelin, leptin, insulin and glucose concentrations were measured to evaluate the effects of obesity and weight loss on these parameters in dogs. Body weight, body condition score, thoracic and pelvic perimeters, and ingested food amounts were also recorded during the study. Obese dogs demonstrated a significant decrease in plasma ghrelin and a significant increase in plasma leptin and insulin concentrations when compared with control dogs. During weight loss, significant increases in plasma total ghrelin and glucose and significant decreases in plasma leptin and insulin were observed. The increase in plasma ghrelin concentrations seemed to be transient. Body weight and the morphometric parameters correlated positively with leptin concentrations and negatively with total ghrelin concentrations. These results suggest that ghrelin and leptin could play a role in dogs in the adaptation to a positive or negative energy balance, as observed in humans.

Animals↗

PubMed2005

Uncoupling protein 1 is necessary for norepinephrine-induced glucose utilization in brown adipose tissue.

Sympathetic stimulation activates glucose utilization in parallel with fatty acid oxidation and thermogenesis in brown adipose tissue (BAT) through the beta-adrenergic receptors. To clarify the roles of the principal thermogenic molecule mitochondrial uncoupling protein 1 (UCP1) in the sympathetically stimulated glucose utilization, we investigated the uptake of 2-deoxyglucose (2-DG) into BAT and some other tissues of UCP1-knockout (KO) mice in vivo. In wild-type (WT) mice, administration of norepinephrine (NE) accelerated the disappearance of plasma 2-DG and increased 2-DG uptake into BAT and heart without any rise of plasma insulin level. In UCP1-KO mice, the stimulatory effect of NE on 2-DG uptake into BAT, but not into heart, disappeared completely. Insulin administration increased 2-DG uptake into BAT and also heart similarly in WT and UCP1-KO mice. NE also increased the activity of AMP-activated protein kinase (AMP kinase) in BAT of WT but not UCP1-KO mice. Our results, together with reports that the activation of AMP kinase increases glucose transport in myocytes, suggest that the sympathetically stimulated glucose utilization in BAT is due to the serial activation of UCP1 and AMP kinase.

Adipose Tissue, Brown↗

PubMed2004

Hepatocyte growth factor/scatter factor suppresses TNF-alpha-induced E-selectin expression in human umbilical vein endothelial cells.

Induction of E-selectin on endothelial cell surface initiates leukocyte adhesion and subsequent migration into the subendothelium. Here, we tested the effect of hepatocyte growth factor (HGF) on inflammatory cytokine-induced expression of E-selectin and consequent leukocyte-endothelial cell interaction using human umbilical vein endothelial cells (HUVEC). Prior treatment of HUVEC with HGF significantly attenuated the tumor necrosis factor (TNF)-alpha-induced E-selectin protein, adhesion of HL60 cells to HUVEC and E-selectin mRNA expression in a dose-dependent manner, while HGF itself did not exert any effects. The HGF effects on the mRNA expression were inhibited in the presence of N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, which also abolished HGF-stimulated eNOS activity. These results suggest HGF plays cardiovascular protective functions mediated, at least in part, through nitric oxide-dependent suppression of inflammatory cytokine-induced E-selectin expression and subsequent tethering of leukocytes to endothelial cells.

Cell Adhesion↗

PubMed2004

Cloning of bovine MAIL and its mRNA expression in white blood cells of Holstein cows.

Molecule possessing ankyrin-repeats induced by lipopolysaccharide (MAIL) is known as an IkappaB protein induced after administration of bacterial lipopolysaccharide (LPS) to mice. In the present study, we cloned bovine MAIL cDNA and examined its mRNA expression in white blood cells isolated from Holstein cows. Bovine MAIL had more than 80% amino acid identities with murine and human MAILs, highly conserved ankyrin-repeat motifs and PEST-like sequences. Bovine MAIL mRNA was undetectable in isolated peripheral white blood cells, but rapidly induced (<1h) after stimulation by LPS and lipid A in vitro in a dose-dependent manner. The lipid A-induced MAIL mRNA expression was found in polymorphonuclear cells, monocytes/macrophages and total lymphocytes, but not in T-lymphocytes. MAIL mRNA was also induced in vivo in peripheral blood leukocytes of cows after intramammary injection of Escherichia coli derived from coliform mastitis. Thus, bovine MAIL, as rodent MAILs, is induced by inflammatory stimuli in specific immune cells in vitro and in vivo, suggesting a role in inflammatory responses to bacterial infection in cattle.

Amino Acid Motifs↗

PubMed2004

The expression of src-suppressed C kinase substrate (SSeCKS) and uptake of exogenous particles in endothelial and reticular cells.

Src-suppressed C kinase substrate (SSeCKS), a potent tumor suppressor, plays a role in membrane-cytoskeletal remodeling to regulate mitogenesis, cell differentiation, and motility. Our previous study showed that lipopolysaccharide (LPS) induced a selective and strong expression of SSeCKS in the vascular endothelial cells of several organs, such as hepatic sinusoids, and in the reticular cells of lymphoid organs. In the present immunocyto-chemical study, we determined the detailed cellular and subcellular localization of SSeCKS in mouse tissues after LPS administration, and examined the involvement of SSeCKS in the uptake of exogenous particles. SSeCKS immunoreactivity in the liver and lymph nodes was below the detectable level under normal conditions. After LPS stimulation, an intense immunoreactivity for SSeCKS became noticeable in sinusoidal endothelial cells of the liver and medullary reticular cells of the lymph node. Electron-microscopically, the immunoreactivity was localized predominantly along the cytoplasmic membrane of both cell types. These cells in normal mice incorporated a small amount of injected particles (carbon particles and latex beads), while after LPS stimulation, the uptake of particles increased in terms of the amount and extent of the uptaking sites. Endothelial cells and reticular cells without SSeCKS expression could not incorporate any particles even after LPS stimulation. The subcellular localization of SSeCKS in endothelial cells correlated with some pinocytic pits and phago-lysosomes, although a diffuse distribution of SSeCKS in the cytoplasm was also visible. Taken together, these findings indicate that SSeCKS expression in endothelial cells and reticular cells is a functional index of the reticulo-endothelial system and is involved in the uptake of particles from blood and lymph circulation.

A Kinase Anchor Proteins↗