Oncostatin M induces upregulation of claudin-2 in rodent hepatocytes coinciding with changes in morphology and function of tight junctions

In rodent livers, integral tight junction (TJ) proteins claudin-1, -2, -3, -5 and -14 are detected and play crucial roles in the barrier to keep bile in bile canaculi away from the blood circulation. Claudin-2 shows a lobular gradient increasing from periportal to pericentral hepatocytes, whereas claudin-1 and -3 are expressed in the whole liver lobule. Although claudin-2 expression induces cation-selective channels in tight junctions of epithelial cells, the physiological functions and regulation of claudin-2 in hepatocytes remain unclear. Oncostatin M (OSM) is a multifunctional cytokine implicated in the differentiation of hepatocytes that induces formation of E-cadherin-based adherens junctions in fetal hepatocytes. In this study, we examined whether OSM could induce expression and function of claudin-2 in rodent hepatocytes, immortalized mouse and primary cultured proliferative rat hepatocytes. In the immortalized mouse and primary cultured proliferative rat hepatocytes, treatment with OSM markedly increased mRNA and protein of claudin-2 together with formation of developed networks of TJ strands. The increase of claudin-2 enhanced the paracellular barrier function which depended on molecular size. The increase of claudin-2 expression induced by OSM in rodent hepatocytes was regulated through distinct signaling pathways including PKC. These results suggest that expression of claudin-2 in rodent hepatocytes may play a specific role as controlling the size of paracellular permeability in the barrier to keep bile in bile canaculi.     

Gliclazide inhibits proliferation but stimulates differentiation of white and brown adipocytes

Gliclazide, a second-generation sulfonylurea, has anti-oxidant properties as well as hypoglycemic activities. In the present study, we investigated whether gliclazide affected proliferation and/or differentiation of HW white and HB2 brown adipocyte cell lines. Gliclazide inhibited proliferation of HW and HB2 cells in the medium containing fetal calf serum or epidermal growth factor (EGF). Gliclazide inhibited phosphorylation of EGF receptor and of extracellular signal-regulated kinase (ERK) 1/2 stimulated by EGF. Gliclazide increased lipid accumulation and peroxisome proliferator-activated receptor gamma (PPARgamma) expression in the early stage of differentiation of adipocytes. A K(ATP) channel activator, diazoxide, did not inhibit the increase of lipid accumulation by gliclazide. Furthermore, gliclazide inhibited the DNA-binding activity of PPARgamma in mature adipocytes. On the other hand, glibenclamide, other sulfonylurea, did not show these effects. These results indicate gliclazide inhibits proliferation and stimulates differentiation of adipocytes via down-regulation of the EGFR signalling. Gliclazide may have preventive and therapeutic effects on obesity, as well as on type 2 diabetes.     

Isolation, cloning, and characterization of a novel phosphomannan-binding lectin from porcine serum

Mannan-binding protein (MBP) is a C-type serum lectin that is an important constituent of the innate immune defense because it activates the complement system via the lectin pathway. While the pig has been proposed to be an attractive source of xenotransplantable tissues and organs, little is known about porcine MBP. In our previous studies, phosphomannan, but not mannan, was found to be an effective inhibitor of the C1q-independent bactericidal activity of newborn piglet serum against some rough strains of Gram-negative bacteria. In contrast, the inhibitory activities of phosphomannan and mannan were very similar in the case of MBP-dependent bactericidal activity against rough strains of Escherichia coli K-12 and S-16. Based on these findings, we inferred that an MBP-like lectin with slightly or completely different carbohydrate binding specificity might exist in newborn piglet serum and be responsible for the C1q-independent bactericidal activity. Herein we report that a novel phosphomannan-binding lectin (PMBL) of 33 kDa under reducing conditions was isolated from both newborn and adult porcine serum and characterized. Porcine PMBL functionally activated the complement system via the lectin pathway triggered by binding with both phosphomannan (P-mannan) and mannan, which, unlike MBP, was effectively inhibited by mannose 6-phosphate- or galatose-containing oligosaccharides. Our observations suggest that porcine PMBL plays a critical role in the innate immune defense from the newborn stage to adult-hood, and the establishment of a newborn piglet experimental model for the innate immune system studies is a valuable step toward elucidation of the physiological function and molecular mechanism of lectin pathway.     

Physiological effects of Shinrin-yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan

The physiological effects of "Shinrin-yoku" (taking in the atmosphere of the forest) were examined by investigating blood pressure, pulse rate, heart rate variability (HRV), salivary cortisol concentration, and immunoglobulin A concentration in saliva. Subjective feelings of being "comfortable", "calm", and "refreshed" were also assessed by questionnaire. The subjects were 12 male university students aged from 21 to 23 (mean+/-SD: 22.0+/-1.0). The physiological measurements were conducted six times, i.e., in the morning and evening before meals at the place of accommodation, before and after the subjects walked a predetermined course in the forest and city areas for 15 minutes, and before and after they sat still on a chair watching the scenery in the respective areas for 15 minutes. The findings were as follows. In the forest area compared to the city area, 1) blood pressure and pulse rate were significantly lower, and 2) the power of the HF component of the HRV tended to be higher and LF/(LF+HF) tended to be lower. Also, 3) salivary cortisol concentration was significantly lower in the forest area. These physiological responses suggest that sympathetic nervous activity was suppressed and parasympathetic nervous activity was enhanced in the forest area, and that "Shinrin-yoku" reduced stress levels. In the subjective evaluation, 4) "comfortable", "calm", and "refreshed" feelings were significantly higher in the forest area. The present study has, by conducting physiological investigations with subjective evaluations as supporting evidence, demonstrated the relaxing and stress-relieving effects of "Shinrin-yoku".     

Stochastic thermodynamic limit on E. coli adaptation by information geometric approach

Biological systems process information under noisy environment. Sensory adaptation model of E. coli is suitable for investigation because of its simplicity. To understand the adaptation processing quantitatively, stochastic thermodynamic approach has been attempted. Information processing can be assumed as state transition of a system that consists of signal transduction molecules using thermodynamic approach, and efficiency can be measured as thermodynamic cost. Recently, using information geometry and stochastic thermodynamics, a relationship between speed of the transition and the thermodynamic cost has been investigated for a chemical reaction model. Here, we introduce this approach to sensory adaptation model of E. coli, and examined a relationship between adaptation speed and the thermodynamic cost, and efficiency of the adaptation speed. For increasing external noise level in stimulation, the efficiency decreased, but the efficiency was highly robust to external stimulation strength. Moreover, we demonstrated that there is the best noise to achieve the adaptation in the aspect of thermodynamic efficiency. Our quantification method provides a framework to understand the adaptation speed and the thermodynamic cost for various biological systems.     

Disruption of phospholipase B gene, PLB1, increases the survival of baker's yeast Torulaspora delbrueckii

Abstract An uracil auxotrophic mutant of baker's yeast Torulaspora delbrueckii , which is resitant to 5-fluoro-orotic acid, was complemented by transformation with YEp24 which harbors 2 μm origin and URA3 derived from Saccharomyces cerevisiae . The phospholipase B in T. delbrueckii cells is active in both acidic and alkaline conditions. However, activity of phospholipase B gene ( PLB1 ) in cells of disruption mutant ( plbI : : URA3 ) was lost in both conditions, which indicates that all phospholipase B activity is encoded by a single gene (or a single polypeptide) in these yeast cells. Over-expression of PLB1 with YEp plasmid vector in T. delbrueckii cells showed ∼ 2.5-fold increase in phospholipase B activity, comparing with that in wild-type cells. Cells of plb1 Δ mutant showed increased survival when cells of plb1 Δ mutant and wild-type strain were incubated in water at 30 °C. Cells of PLB1 -over-expressed strain died rapidly even during the cultivation period, indicating that phospholipase B activity may be a determinant for the survival of this yeast.     

Cloning,sequence and variability analysis of expressed immunoglobulin light chain genes from yellowtail Seriola quinqueradiata

The cDNA clones encoding immunoglobulin (Ig) light (L) chain variable (V) region associated with constant (C) region were isolated from yellowtail (Seriola quinqueradiata) kidney by expressed sequence tag analysis (accession numbers: AB062619-AB062668, AB064322). The sequences of both VL and CL region contain well-conserved cysteine residues important for intra- and inter-domain interaction in mammals. Comparisons of the amino acid sequence of the CL domain with those of other species showed a high degree of similarity, with 88.3%, 59.8%, and 60.6% to those of wolf fish (Anarhichas lupus), rainbow trout IgL I isotype (Oncorhynchus mykiss) and channel catfish G isotype (Ictalurus punctatus), respectively. Multiple sequence alignments of the CL domain with those of higher vertebrates, however, did not readily allow it to be classified as kappa or lambda isotypes. Furthermore, the pI, hydrophobicity and variability of yellowtail VL regions were studied in 65 cDNA clones and the diversity was observed in CDR1, CDR2 and CDR3 regions.