Urotensin II, a peptide hormone from the caudal neurosecretory system of the teleost, Gillichthys mirabilis, was isolated by using classical chromatographic techniques and high-performance liquid chromatography (HPLC). Direct microtechniques for sequence determination were used to establish its structure. Urotensin II from Gillichthys is a 1363-dalton dodecapeptide with the amino acid sequence AlaGly-Thr-Ala-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val. This sequence is homologous with somatostatin in positions 1 and 2 and 7-9. The sequence has been verified by the production of a bioactive synthetic urotensin II. The possible chemical and physiological significance of its homology to somatostatin is discussed.

cDNA clones coding for tenascin, an extracellular matrix glycoprotein with a restricted tissue distribution, were isolated from a chicken fibroblast cDNA expression library using a specific tenascin antiserum. Antibodies eluted from the cDNA‐encoded fusion proteins reacted exclusively with tenascin. Limited trypsin treatment of purified tenascin resulted in a peptide which confirmed the deduced protein sequences. The largest clone encoding 632 amino acids showed a cysteine‐rich region containing 13 consecutive epidermal growth factor‐like repeats of unusual uniformity. Northern blot analysis revealed 8‐ to 9‐kb messages. Tenascin is shown to be induced in vitro by fetal calf serum as well as by transforming growth factor beta (TGF‐beta). A 4‐fold increase in tenascin secretion by chick embryo fibroblasts was seen after TGF‐beta treatment. The induction of tenascin protein synthesis was preceded by an increase of tenascin mRNA as determined by Northern blot analysis. The induction of tenascin was compared with fibronectin. The accumulation of the two extracellular matrix proteins in the medium was differentially affected by fetal calf serum and TGF‐beta and the increase was in both cases higher for tenascin.

Two adhesive events critical to efficient recruitment of neutrophils at vascular sites of inflammation are up-regulation of endothelial selectins that bind sialyl Lewisx ligands and activation of β2-integrins that support neutrophil arrest by binding ICAM-1. We have previously reported that neutrophils rolling on E-selectin are sufficient for signaling cell arrest through β2-integrin binding of ICAM-1 in a process dependent upon ligation of L-selectin and P-selectin glycoprotein ligand 1 (PSGL-1). Unresolved are the spatial and temporal events that occur as E-selectin binds to human neutrophils and dynamically signals the transition from neutrophil rolling to arrest. Here we show that binding of E-selectin to sialyl Lewisx on L-selectin and PSGL-1 drives their colocalization into membrane caps at the trailing edge of neutrophils rolling on HUVECs and on an L-cell monolayer coexpressing E-selectin and ICAM-1. Likewise, binding of recombinant E-selectin to PMNs in suspension also elicited coclustering of L-selectin and PSGL-1 that was signaled via mitogen-activated protein kinase. Binding of recombinant E-selectin signaled activation of β2-integrin to high-avidity clusters and elicited efficient neutrophil capture of β2-integrin ligands in shear flow. Inhibition of p38 and p42/44 mitogen-activated protein kinase blocked the cocapping of L-selectin and PSGL-1 and the subsequent clustering of high-affinity β2-integrin. Taken together, the data suggest that E-selectin is unique among selectins in its capacity for clustering sialylated ligands and transducing signals leading to neutrophil arrest in shear flow.

The adhesion molecules known as selectins mediate the capture of neutrophils from the bloodstream. We have previously reported that ligation and cross-linking of L-selectin on the neutrophil surface enhances the adhesive function of ␤ 2 -integrins in a synergistic manner with chemotactic agonists. In this work, we examined degranulation and adhesion of neutrophils in response to cross-linking of L-selectin and addition of interleukin-8. Cross-linking of L-selectin induced priming of degranulation that was similar to that observed with the alkaloid cytochalasin B. Activation mediated by L-selectin of neutrophil shape change and adhesion through CD11b/CD18 were strongly blocked by Merck C, an imidazole-based inhibitor of p38 mitogen-activated protein kinase (MAPK), but not by a structurally similar non-binding regioisomer. Priming by L-selectin of the release of secondary, tertiary, and secretory, but not primary, granules was blocked by inhibition of p38 MAPK. Peak phosphorylation of p38 MAPK was observed within 1 min of cross-linking L-selectin, whereas phosphorylation of ERK1/2 was highest at 10 min. Phosphorylation of p38 MAPK, but not ERK1/2, was inhibited by Merck C. These data suggest that signal transduction as a result of clustering L-selectin utilizes p38 MAPK to effect neutrophil shape change, integrin activation, and the release of secondary, tertiary, and secretory granules.Neutrophils circulate in the vasculature in a passive state and become more adhesive upon stimulation at sites of inflammation. Margination to the vessel wall and subsequent transmigration and phagocytosis (1) requires a number of surface proteins, including the ␤ 2 -integrins and the selectins, as mediators of adherence to the endothelium (2-5). A sequence of molecular and biophysical events has been identified that facilitates neutrophil activation and increased adherence during the acute inflammatory response in vivo. Neutrophils entering post-capillary venules adjacent to inflammatory foci develop transient rolling adhesive interactions with endothelium via selectins (6). Following exposure to inflammatory cytokines such as tumor necrosis factor and interleukin-1, endothelial cells are induced to express E-selectin and P-selectin (6). Several surface glycoproteins on neutrophils, including L-selectin and P-selectin glycoprotein ligand 1, present oligosaccharide moieties that serve as counter receptors for E-selectin and P-selectin. In conjunction with neutrophil membrane L-selectin, which recognizes oligosaccharides on endothelial cells,

The nucleotide sequences of a Schizosaccharomyces pombe opal suppressor serine tRNA gene (sup9‐e) and of 12 in vivo‐generated mutant genes, which have lost the ability to suppress UGA mutations, have been determined. Analysis of the expression of these genes in Saccharomyces cerevisiae in vitro and in vivo systems has revealed defects in tRNA gene transcription and precursor tRNA processing. Single base changes in the D‐loop, the intron and the extra arm affect the efficiency of splicing of the tRNA precursors while an anti‐codon stem mutation may affect the accuracy of this process. Two mutations which occur in the intervening sequence of the sup9‐e gene allow an alternate tRNA base pairing configuration. Transcription of the sup9‐e gene and of the adjacent tRNAMet gene (located 7 bp downstream) is essentially abolished in vivo by a G–‐A19 mutation in the tRNASer gene, suggesting that tRNAMet may be derived solely via processing of the tRNASer‐tRNAMet dimeric precursor.