Origin of bombesin-like peptides in human fetal lung

Four different forms of bombesin-like immunoreactive peaks were detected in extracts of human fetal lung by the use of reversed-phase high performance liquid chromatography (HPLC). Peaks I, II, III and IV, (increasing retention time), were eluted using a 14-38% of acetonitrile gradient containing 0.1% trifluoroacetic acid (TFA). Peak II was the major material found in the extract of human fetal lung obtained at 16-20 weeks gestation. None of the four compounds contained in the eluted peaks had the same retention time as amphibian bombesin or porcine gastrin releasing peptide (GRP). On reversed-phase HPLC using two different solvent systems TFA or heptafluorobutyric acid (HFBA) as a hydrophobic counter ion, and in gel filtration chromatography, the chromatographic behavior of the main peak (peak II) was the same as that of the carboxyl terminal fragments of GRP, GRP18-27 or GRP19-27. This suggested that the peptide(s) in peak II resembled in composition the carboxy terminal 9 or 10 amino acids of porcine GRP. Following tryptic digestion the material in peak IV was converted to the more polar compound present in peak II. Two other peptide peaks were eluted close to peak II and these were presumed to be a modification of this main peak. One of the possible biosynthetic steps in the formation of bombesin-like peptides in human fetal lung could be a tryptic conversion of a less polar peptide to a more polar form (peak IV to II).     

Hepatocellular protection by nitric oxide or nitrite in ischemia and reperfusion injury

Ischemia and reperfusion (I/R)-induced liver injury occurs in several pathophysiological disorders including hemorrhagic shock and burn as well as resectional and transplantation surgery. One of the earliest events associated with reperfusion of ischemic liver is endothelial dysfunction characterized by the decreased production of endothelial cell-derived nitric oxide (NO). This rapid post-ischemic decrease in NO bioavailability appears to be due to decreased synthesis of NO, enhanced inactivation of NO by the overproduction of superoxide or both. This review presents the most current evidence supporting the concept that decreased bioavailability of NO concomitant with enhanced production of reactive oxygen species initiates hepatocellular injury and that endogenous NO or exogenous NO produced from nitrite play important roles in limiting post-ischemic tissue injury.     

Reduced cell number in the hindgut epithelium disrupts hindgut left–right asymmetry in a mutant of pebble,encoding a RhoGEF,in Drosophila embryos

Animals often show left–right (LR) asymmetry in their body structures. In some vertebrates, the mechanisms underlying LR symmetry breaking and the subsequent signals responsible for LR asymmetric development are well understood. However, in invertebrates, the molecular bases of these processes are largely unknown. Therefore, we have been studying the genetic pathway of LR asymmetric development in Drosophila. The embryonic gut is the first organ that shows directional LR asymmetry during Drosophila development. We performed a genetic screen to identify mutations affecting LR asymmetric development of the embryonic gut. From this screen, we isolated pebble (pbl), which encodes a homolog of a mammalian RhoGEF, Ect2. The laterality of the hindgut was randomized in embryos homozygous for a null mutant of pbl. Pbl is a multi-functional protein required for cytokinesis and the epithelial-to-mesenchymal transition in Drosophila. Consistent with Pbl’s role in cytokinesis, we found reduced numbers of cells in the hindgut epithelium in pbl homozygous embryos. The specific expression of pbl in the hindgut epithelium, but not in other tissues, rescued the LR defects and reduced cell number in embryonic pbl homozygotes. Embryos homozygous for string (stg), a mutant that reduces cell number through a different mechanism, also showed LR defects of the hindgut. However, the reduction in cell number in the pbl mutants was not accompanied by defects in the specification of hindgut epithelial tissues or their integrity. Based on these results, we speculate that the reduction in cell number may be one reason for the LR asymmetry defect of the pbl hindgut, although we cannot exclude contributions from other functions of Pbl, including regulation of the actin cytoskeleton through its RhoGEF activity.     

Structural analysis of an acidic, fatty acid ester-bonded extracellular polysaccharide produced by a pristane-assimilating marine bacterium, Rhodococcus erythropolis PR4

Rhodococcus erythropolis PR4 is a marine bacterium that can degrade various alkanes including pristane, a C(19) branched alkane. This strain produces a large quantity of extracellular polysaccharides, which are assumed to play an important role in the hydrocarbon tolerance of this bacterium. The strain produced two acidic extracellular polysaccharides, FR1 and FR2, and the latter showed emulsifying activity toward clove oil, whereas the former did not. FR2 was composed of D-galactose, D-glucose, D-mannose, D-glucuronic acid, and pyruvic acid at a molar ratio of 1:1:1:1:1, and contained 2.9% (w/w) stearic acid and 4.3% (w/w) palmitic acid attached via ester bonds. Therefore, we designated FR2 as a PR4 fatty acid-containing extracellular polysaccharide or FACEPS. The chemical structure of the PR4 FACEPS polysaccharide chain was determined by 1D (1)H and (13)C NMR spectroscopies as well as by 2D DQF-COSY, TOCSY, HMQC, HMBC, and NOESY experiments. The sugar chain of PR4 FACEPS was shown to consist of tetrasaccharide repeating units having the following structure: [structure: see text].     

A simple quantitative chiral analysis of amino acid esters by fluorine‐19 nuclear magnetic resonance using the modified James–Bull method

A simple chiral analysis of amino acid esters by fluorine‐19 nuclear magnetic resonance (¹⁹F NMR) through the modified James–Bull method is described. Thus, amino acid ester acid salt was treated with 5‐fluoro‐2‐formylphenylboronic acid and (S)‐BINOL in the presence of triethylamine (TEA) and MS4A for 10 minutes. The reaction mixture was analysed by ¹⁹F NMR directly to afford good quantifications.     

Hepatic neuroendocrine carcinoma in a Japanese macaque (Macaca fuscata)

Primary neuroendocrine neoplasm of the liver is extremely rare in both humans and non‐human primates. The present report describes the clinical and pathological findings of an aged Japanese macaque (Macaca fuscata) with hepatic neuroendocrine carcinoma. To our knowledge, this is the first report of hepatic neuroendocrine neoplasm in macaques.     

Scavenger receptor CL-P1 mediates endocytosis by associating with AP-2μ2

Background

Scavenger receptor CL-P1 (collectin placenta 1) has been found recently as a first membrane-type collectin which is mainly expressed in vascular endothelial cells. CL-P1 can endocytose OxLDL as well as microbes but in general, the endocytosis mechanism of a scavenger receptor is not well elucidated.

Methods

We screened a placental cDNA library using a yeast two-hybrid system to detect molecules associated with the cytoplasmic domain of CL-P1. We analyzed the binding and endocytosis of several ligands in CL-P1 transfectants and performed the inhibition study using tyrphostin A23 which is a specific inhibitor of tyrosine kinase, especially in μ2-dependent endocytosis and the site-directed mutagenesis in the endocytosis YXXΦ motif in CL-P1 cytoplasmic region. Furthermore, the SiRNA study of clathrin, adaptor AP-2 and dynamin-2 during the endocytosis of OxLDL in CL-P1 transfectant cells was carried out.

Results

We identified μ2 subunit of the AP-2 adaptor complex as a molecule associated with the cytoplasmic region of CL-P1. We demonstrated that AP-2μ2 was essential for CL-P1 mediated endocytosis of OxLDL in CL-P1 transfectant cells and its endocytosis was also mediated by clathrin, dynamin and adaptin complex molecules.

Conclusions

Tyrosine-based YXXΦ sequences play an important role in CL-P1-mediated OxLDL endocytosis associated with AP-2μ2.

General Significance

This might be the first finding of the clear endocytosis mechanism in scavenger receptor CL-P1.