Convergent synthesis and in vivo inhibitory effect on fat accumulation of (-)-ternatin, a highly N-methylated cyclic peptide

(-)-Ternatin (1), a highly N-methylated cyclic heptapeptide, is a potent inhibitor of fat accumulation against 3T3-L1 murine adipocytes (EC50 = 0.14 microg/mL) [Shimokawa, K.; Mashima, I.; Asai, A.; Yamada, K.; Kita, M.; Uemura, D. Tetrahedron Lett. 2006, 47, 4445]. Compound 1 was synthesized from Boc-protected amino acids in solution. Upon treatment with 1 at 5 mg/kg/day, increases in body weight and fat accumulation in high-fat-fed mice were both significantly suppressed.     

Litter dynamics and its effects on the survival of <Emphasis Type="Italic">Castanopsis sieboldii</Emphasis> seedlings in a subtropical forest in southern Japan

Based on direct field measurement, this study quantitatively estimated the litter dynamics on the forest floor for a 1-year-period and then investigated its influence on the seedling dynamics of Castanopsis sieboldii, as well as interactions with adults in a subtropical forest in southern Japan. Litter dynamics is composed of three major components: falling litter, transport, and decomposition on the forest floor. Litterfall was measured by litter traps and did not exhibit clear spatial tendency. Lateral input was assessed by newly accumulated litter beneath the traps and showed no spatial variation, either. In contrast, lateral output of litter, which was quantified from disappearance of artificial litter, was correlated with local topography. Consequently, we found considerable spatial variations and seasonal changes in litter dynamics on the forest floor. In addition, we constructed survival models of C. sieboldii seedlings at the individual level. The lateral movement of accumulated litter had an influence on the survival of seedlings, which mostly occurred in periods of typhoons with heavy rain. Meanwhile, the distance from canopy trees, which is assumed to be a spacing mechanism due to seedling/adult interactions, played a lesser role in this subtropical forest. Our results suggest that the stability of accumulated litter on the forest floor was a predominant factor in the spatial dynamics of the early life stage of C. sieboldii.     

Expression of silent mating type information regulator 2 homolog 1 and its role in human intervertebral disc cell homeostasis

Introduction  

Intervertebral disc tissue homeostasis is modulated by a variety of molecules. Silent mating type information regulator 2 homolog 1 (SIRT1) plays a key role in various physiological processes. The aim of the present study was to verify the expression of SIRT1 and determine SIRT1 function in human intervertebral disc cell homeostasis.     

Molecular analysis of X-linked inborn errors of purine metabolism: HPRT1 and PRPS1 mutations

Mutations of two enzyme genes, HPRT1 encoding hypoxanthine guanine phosphoribosyltransferase (HPRT) and PRPS1 encoding a catalytic subunit (PRS-I) of phosphoribosylpyrophosphate synthetase, cause X-linked inborn errors of purine metabolism. Analyzing these two genes, we have identified three HPRT1 mutations in Lesch-Nyhan families following our last report. One of them, a new mutation involving the deletion of 4224 bp from intron 4 to intron 5 and the insertion of an unknown 28 bp, has been identified. This mutation resulted in an enzyme polypeptide with six amino acids deleted due to abnormal mRNA skipping exon 5. The other HPRT1 mutations, a single base deletion (548delT, 183fs189X), and a point mutation causing a splicing error (532+1G>A, 163fs165X) were detected first in Japanese patients but have been reported in European families. On the other hand, in the analysis of PRPS1, no mutation was identified in any patient.     

A novel mechanism of autolysis in Helicobacter pylori: possible involvement of peptidergic substances

BACKGROUND: Helicobacter pylori survival in a hostile acidic environment is known to be caused by its production of urease, which is not released by known secretion pathways. It has been proposed that H. pylori cells undergo spontaneous autolysis during cultivation and that urease becomes surface-associated only concomitant with bacterial autolysis. The aim of this study was to elucidate mechanisms by which H. pylori cells undergo autolysis during cultivation. MATERIALS AND METHODS: Autolysis of H. pylori KZ109 cells was estimated by measuring the turbidity of the culture, by detection of cytoplasmic protein release into the culture supernatant and by scanning electron microscopic observation of H. pylori cells during cultivation. An autolysis-inducing factor (AIF) was partially purified from the culture supernatant by a partition method using ethyl acetate. RESULTS: Bacterial turbidity of KZ109 cells was drastically decreased after late-log phase accompanying release of urease and HspB into the extracellular space. Concomitantly, cell lytic activity was detected in the culture supernatant. Scanning electron microscopic observation suggested that partially purified AIF induced cell lysis. It was also shown that the AIF is different from other autolytic enzymes or substances so far reported. CONCLUSIONS: This study demonstrated the presence of the peptidergic autolytic substances in the culture supernatant of H. pylori KZ109 cells. The results of this study should be useful for further studies aimed at elucidation of the strategy of survival of H. pylori in the gastric environment and elucidation of the mechanisms of pathogenesis induced by H. pylori.     

Orally tolerized T cells can form conjugates with APCs but are defective in immunological synapse formation

Oral tolerance is systemic immune hyporesponsiveness induced by the oral administration of soluble Ags. Hyporesponsiveness of Ag-specific CD4 T cells is responsible for this phenomenon. However, the molecular mechanisms underlying the hyporesponsive state of these T cells are not fully understood. In the present study, we investigated the ability of orally tolerized T cells to form conjugates with Ag-bearing APCs and to translocate TCR, protein kinase C-theta (PKC-theta), and lipid rafts into the interface between T cells and APCs. Orally tolerized T cells were prepared from the spleens of OVA-fed DO11.10 mice. Interestingly, the orally tolerized T cells did not show any impairment in the formation of conjugates with APCs. The conjugates were formed in a LFA-1-dependent manner. Upon antigenic stimulation, the tolerized T cells could indeed activate Rap1, which is critical for LFA-1 activation and thus cell adhesion. However, orally tolerized T cells showed defects in the translocation of TCR, PKC-theta, and lipid rafts into the interface between T cells and APCs. Translocation of TCR and PKC-theta to lipid raft fractions upon antigenic stimulation was also impaired in the tolerized T cells. Ag-induced activation of Vav, Rac1, and cdc42, which are essential for immunological synapse and raft aggregation, were down-regulated in orally tolerized T cells. These results demonstrate that orally tolerized T cells can respond to specific Ags in terms of conjugate formation but not with appropriate immunological synapse formation. This may account for the hyporesponsive state of orally tolerized T cells.     

Paramagnetic NMR study of Cu(2+)-IDA complex localization on a protein surface and its application to elucidate long distance information

The paramagnetic metal chelate complex Cu(2+)-iminodiacetic acid (Cu(2+)-IDA) was mixed with ubiquitin, a small globular protein. Quantitative analyses of (1)H and (15)N chemical shift changes and line broadenings induced by the paramagnetic effects indicated that Cu(2+)-IDA was localized to a histidine residue (His68) on the ubiquitin surface. The distances between the backbone amide proton and the Cu(2+) relaxation center were evaluated from the proton transverse relaxation rates enhanced by the paramagnetic effect. These correlated well with the distances calculated from the crystal structure up to 20 A. Here, we show that a Cu(2+)-IDA is the first paramagnetic reagent that specifically localizes to a histidine residue on the protein surface and gives the long-range distance information.