Interaction of antimannan with glycopeptides

Taka amylase A glycopeptide (TA-GP) strongly inhibited the interaction of antimannan (antibodies directed towards mannan from $\text{Saccharomyces cerevisiae}$) with yeast mannan, whereas ovalbumin glycopeptide (OA-GP) did so only poorly. We inferred that this is due to the strong reactivity of antimannan with terminal trimannosides composed of Manα1→2Man or Manα1→3Man linkages which occur in mannan and TA-GP. In contrast, TA-GP and OA-GP were nearly equally reactive with concanavalin A having the ability to interact with terminal mannose and 2-0-mannose residues which occur abundantly in these glycopeptides. Thus, antimannan should be useful as a probe for characterizing glycoproteins from extracellular fluids or cellular membranes.     

Northern richness and southern poverty: contrasting genetic footprints of glacial refugia in the relictual tree Sciadopitys verticillata (Coniferales: Sciadopityaceae)

Sciadopitys verticillata is amongst the most relictual of all plants, being the last living member of an ancient conifer lineage, the Sciadopityaceae, and is distributed in small and disjunct populations in high rainfall regions of Japan. Although mega‐fossils indicate the persistence of the species within Japan through the Pleistocene glacial–interglacial cycles, how the species withstood the colder and drier climates of the glacials is not well known. The present study utilized phylogeography and palaeodistribution modelling to test whether the species survived within pollen‐based coastal temperate forest glacial refugia or within previously unidentified refugia close to its current range. Sixteen chloroplast haplotypes were found that displayed significant geographical structuring. Unexpectedly, northern populations in central Honshu most distant from coastal refugia had the highest chloroplast diversity and were differentiated from the south, a legacy of glacial populations possibly in inland river valleys close to its current northern range. By contrast, populations near putative coastal refugia in southern Japan, harboured the lower chloroplast diversity and were dominated by a single haplotype. Fragment size polymorphism at a highly variable and homoplasious mononucleotide repeat region in the trnT‐trnL intergenic spacer reinforced the contrasting patterns of diversity observed between northern and southern populations. The divergent histories of northern and southern populations revealed in the present study will inform the management of this globally significant conifer. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 263–277.     

Identification and characterization of a resident vascular stem/progenitor cell population in preexisting blood vessels

Vasculogenesis, the in-situ assembly of angioblast or endothelial progenitor cells (EPCs), may persist into adult life, contributing to new blood vessel formation. However, EPCs are scattered throughout newly developed blood vessels and cannot be solely responsible for vascularization. Here, we identify an endothelial progenitor/stem-like population located at the inner surface of preexisting blood vessels using the Hoechst method in which stem cell populations are identified as side populations. This population is dormant in the steady state but possesses colony-forming ability, produces large numbers of endothelial cells (ECs) and when transplanted into ischaemic lesions, restores blood flow completely and reconstitutes de-novo long-term surviving blood vessels. Moreover, although surface markers of this population are very similar to conventional ECs, and they reside in the capillary endothelium sub-population, the gene expression profile is completely different. Our results suggest that this heterogeneity of stem-like ECs will lead to the identification of new targets for vascular regeneration therapy.     

BACE1 modulates filopodia-like protrusions induced by sodium channel beta4 subunit

Processing of APP by BACE1 plays a crucial role in the pathogenesis of Alzheimer disease (AD). Recently, the voltage-gated sodium channel (Na_v) β4 subunit (β4), an auxiliary subunit of Na_v that is supposed to serve as a cell adhesion molecule, has been identified as a substrate for BACE1. However, the biological consequence of BACE1 processing of β4 remains illusive. Here, we report the biological effects of β4 processing by BACE1. Overexpression of β4 in Neuro2a cells promoted neurite extension and increased the number of F-actin rich filopodia-like protrusions. While coexpression of BACE1 together with β4 further accelerated neurite extension, the number of filopodia-like protrusions was reduced. Overexpression of C-terminal fragment of β4 that was generated by BACE1 (β4-CTF) partially recapitulated the results obtained with BACE1 overexpression. These results suggest that the processing of β4 by BACE1 regulates neurite length and filopodia-like protrusion density in neurons.     

Contribution of conserved Asn residues to the inhibitory activities of Kunitz-type protease inhibitors from plants

Plant Kunitz-type protease inhibitors contain a conserved Asn residue in the N-terminal region. To investigate the role of Asn residue in protease inhibitory activities, Erythrina variegata trypsin inhibitor a (ETIa), E. variegata chymotrypsin inhibitor (ECI), and their mutants, ETIa-N12A and ECI-N13A, were used. Both mutants exhibit weaker inhibitory activities toward their cognate proteases than the wild-type proteins and were readily cleaved at reactive sites. Furthermore, kinetic analysis of the interactions of the mutated proteins with their cognate proteases by surface plasmon resonance (SPR) measurement indicated that replacements of the Asn residue mainly affected dissociation rate constants. The conserved Asn residues of Kunitz-type inhibitors play an important role in exhibiting effective inhibitory activity by stabilizing the structures of the primary binding loop and protease-inhibitor complex.     

Possible involvement of Hcn1 ion channel in learning and memory dysfunction in SAMP8 mice

The senescence-accelerated mouse prone 8 (SAMP8) strain exhibits age-related learning and memory deficits (LMD) at 2 months of age. Combined linkage analysis of 264 F2 intercross SAMP8 × JF1 mice and RNA-seq analysis identified Hcn1 gene out of 29 genes in the LMD region on chromosome 13. Hcn1 in SAMP8 strain showed 15 times less polyglutamine repetition compared to Japanese fancy mouse 1 (JF1). Whole cell patch clamp analysis showed that Hcn1 ion conductivity was significantly lower in SAMP8 compared to that of JF1, which may be associated with learning and memory deficiency.     

Activation of peroxisome proliferator-activated receptor-alpha stimulates both differentiation and fatty acid oxidation in adipocytes

Peroxisome proliferator-activated receptor-α (PPARα) is a dietary lipid sensor, whose activation results in hypolipidemic effects. In this study, we investigated whether PPARα activation affects energy metabolism in white adipose tissue (WAT). Activation of PPARα by its agonist (bezafibrate) markedly reduced adiposity in KK mice fed a high-fat diet. In 3T3-L1 adipocytes, addition of GW7647, a highly specific PPARα agonist, during adipocyte differentiation enhanced glycerol-3-phosphate dehydrogenase activity, insulin-stimulated glucose uptake, and adipogenic gene expression. However, triglyceride accumulation was not increased by PPARα activation. PPARα activation induced expression of target genes involved in FA oxidation and stimulated FA oxidation. In WAT of KK mice treated with bezafibrate, both adipogenic and FA oxidation-related genes were significantly upregulated. These changes in mRNA expression were not observed in PPARα-deficient mice. Bezafibrate treatment enhanced FA oxidation in isolated adipocytes, suppressing adipocyte hypertrophy. Chromatin immunoprecipitation (ChIP) assay revealed that PPARα was recruited to promoter regions of both adipogenic and FA oxidation-related genes in the presence of GW7647 in 3T3-L1 adipocytes. These findings indicate that the activation of PPARα affects energy metabolism in adipocytes, and PPARα activation in WAT may contribute to the clinical effects of fibrate drugs.