Human Pluripotent Stem Cell-Derived Tumor Model Uncovers the Embryonic Stem Cell Signature as a Key Driver in Atypical Teratoid/Rhabdoid Tumor

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Legumain/asparaginyl endopeptidase controls extracellular matrix remodeling through the degradation of fibronectin in mouse renal proximal tubular cells

Legumain/asparaginyl endopeptidase (EC 3.4.22.34) is a novel cysteine protease that is abundantly expressed in the late endosomes and lysosomes of renal proximal tubular cells. Recently, emerging evidence has indicated that legumain might play an important role in control of extracellular matrix turnover in various pathological conditions such as tumor growth/metastasis and progression of atherosclerosis. We initially found that purified legumain can directly degrade fibronectin, one of the main components of the extracellular matrix, in vitro. Therefore, we examined the effect of legumain on fibronectin degradation in cultured mouse renal proximal tubular cells. Fibronectin processing can be inhibited by chloroquine, an inhibitor of lysosomal degradation, and can be enhanced by the overexpression of legumain, indicating that fibronectin degradation occurs in the presence of legumain in lysosomes from renal proximal tubular cells. Furthermore, in legumain-deficient mice, unilateral ureteral obstruction (UUO)-induced renal interstitial protein accumulation of fibronectin and renal interstitial fibrosis were markedly enhanced. These findings indicate that legumain might have an important role in extracellular matrix remodeling via the degradation of fibronectin in renal proximal tubular cells.     

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.     

Heart rate and electroencephalogram changes caused by finger acupressure on planta pedis

Preliminary experiments were carried out to investigate the feasibility of using an electroencephalogram and heart rates to evaluate the efficacy of finger acupressure on the key points of planta pedis (both soles). Continuous electroencephalograms were recorded from 19 electrodes based on the International 10-20 electrode placement system on 22 university students (21+/-2.3 years). Spectral power changes were obtained at each electrode site. The power of the alpha1 frequency range (8-10 Hz) increased slightly during acupressure although no statistical significance was observed, while heart rates decreased in all subjects (p<0.05). Cerebral cortex asymmetry in the spectral power changes was not clearly observed during the right and left sole acupressure. This preliminary study suggests that a classification of subjects is necessary in understanding brain wave data during acupressure on soles.     

Structural Analysis of a Trimer of β2-Microgloblin Fragment by Molecular Dynamics Simulations

A peptide ${\beta }_2$-${\text{m}}_{21?31}$, which is a fragment from residue 21 to residue 31 of ${\beta }_2$-microgloblin, is experimentally known to self-assemble and form amyloid fibrils. In order to understand the mechanism of amyloid fibril formations, we applied the replica-exchange molecular dynamics method to the system consisting of three fragments of ${\beta }_2$-${\text{m}}_{21?31}$. From the analyses on the temperature dependence, we found that there is a clear phase transition temperature in which the peptides aggregate with each other. Moreover, we found by the free energy analyses that there are two major stable states: One of them is like amyloid fibrils and the other is amorphous aggregates.     

Daily growth increments in otoliths of wild-caught honmoroko Gnathopogon caerulescens

Otolith growth increments in wild-caught alizarin complex one (ALC)-marked honmoroko Gnathopogon caerulescens were examined to verify the veracity of the age determination method in cyprinids. ALC-marked G. caerulescens recaptured from their natural environment had lapilli increment counts outside the ALC ring mark that had formed on a daily basis during the juvenile stage. This apparently being the first direct evidence of daily periodicity of otolith increment formation in wild-caught cyprinids.     

Predation risk and resource abundance mediate foraging behaviour and intraspecific resource partitioning among consumers in dominance hierarchies

Dominance hierarchies and the resulting unequal resource partitioning among individuals are key mechanisms of population regulation. The strength of dominance hierarchies can be influenced by size‐dependent tradeoffs between foraging and predator avoidance whereby competitively inferior subdominants can access a larger proportion of limiting resources by accepting higher predation risk. Foraging‐predation risk tradeoffs also depend on resource abundance. Yet, few studies have manipulated predation risk and resource abundance simultaneously; consequently, their joint effect on resource partitioning within dominance hierarchies are not well understood. We addressed this gap by measuring behavioural responses of masu salmon Oncorhynchus masou ishikawae to experimental manipulations of predation risk and resource abundance in a natural temperate forest stream. Responses to predation risk depended on body size and social status such that larger fish (often social dominants) exhibited more risk‐averse behaviour (e.g. lower foraging and appearance rates) than smaller subdominants after exposure to a simulated predator. The magnitude of this effect was lower when resources were elevated, indicating that dominant fish accepted a higher predation risk to forage on abundant resources. However, the influence of resource abundance did not extend to the population level, where predation risk altered the distribution of foraging attempts (a proxy for energy intake) from being skewed towards large individuals to being skewed towards small individuals after predator exposure. Our results imply that size‐dependent foraging–predation risk tradeoffs can weaken the strength of dominance hierarchies by allowing competitively inferior subdominants to access resources that would otherwise be monopolized.     

Structural basis of different substrate preferences of two old yellow enzymes from yeasts in the asymmetric reduction of enone compounds

Old yellow enzymes (OYEs) are potential targets of protein engineering for useful biocatalysts because of their excellent asymmetric reductions of enone compounds. Two OYEs from different yeast strains, Candida macedoniensis AKU4588 OYE (CmOYE) and Pichia sp. AKU4542 OYE (PsOYE), have a sequence identity of 46%, but show different substrate preferences; PsOYE shows 3.4-fold and 39-fold higher catalytic activities than CmOYE toward ketoisophorone and (4S)-phorenol, respectively. To gain insights into structural basis of their different substrate preferences, we have solved a crystal structure of PsOYE, and compared its catalytic site structure with that of CmOYE, revealing the catalytic pocket of PsOYE is wider than that of CmOYE due to different positions of Phe²⁴⁶ (PsOYE)/Phe²⁵⁰ (CmOYE) in static Loop 5. This study shows a significance of 3D structural information to explain the different substrate preferences of yeast OYEs which cannot be understood from their amino acid sequences.

Abbreviations: OYE: Old yellow enzymes, CmOYE: Candida macedoniensis AKU4588 OYE, PsOYE: Pichia sp. AKU4542 OYE     

Cloning and Sequencing of the Spore Germination Gene of Bacillus megaterium ATCC 12872: Similarities to the NaH-Antiporter Gene of Enterococcus hirae

The germination mutant TM-31 of Bacillus megaterium ATCC 12872, was isolated by transposon Tn917 insertional mutagenesis. Glucose, L -proline, L -leucine and KNO₃ germinated TM-31 poorly. The DNA in the region of the Tn917 insertion was cloned, and its nucleotide sequence determined. One major open reading frame was present on the cloned DNA. The hydrophobic protein encoded is presumably membrane-associated. A homology search revealed that the gene encoded in the region of the Tn917 insertion is homologous to napA of Enterococcus hirae. napA codes for the NaH-antiporter. It is hypothesized that transport of cations must play an important role in spore germination in B. megaterium ATCC 12872.