Somatostatin-like immunoreactivity in rat thyroid

Summary Somatostatin-like immunoreactive cells of the rat thyroid gland at various ages were investigated immunohistochemically. The number of cells per lobe in 5 m sections increased with age. Immunopositive cells were evident as small clusters in the older age group (8 to 24 months old) but not clustered in the younger age group (3 to 5 months old). This type of proliferation was termed S-cell hyperplasia in a manner similar to C-cell hyperplasia observed in the aged rat thyroid.     

Development of potent and selective small-molecule human Urotensin-II antagonists

This work describes the development of potent and selective human Urotensin-II receptor antagonists starting from lead compound 1, (3,4-dichlorophenyl)methyl{2-oxo-2-[3-phenyl-2-(1-pyrrolidinylmethyl)-1-piperidinyl]ethyl}amine. Several problems relating to oral bioavailability, cytochrome P450 inhibition, and off-target activity at the kappa opioid receptor and cardiac sodium channel were addressed during lead development. hUT binding affinity relative to compound 1 was improved by more than 40-fold in some analogs, and a structural modification was identified which significantly attenuated both off-target activities.     

NK cells regulate CD4 responses prior to antigen encounter

NK cells not only respond rapidly to infection, shaping subsequent adaptive immunity, but also play a role in regulating autoimmune disease. The ability of NK cells to influence adaptive immunity before Ag exposure was examined in a gender-dependent model of preferential Th1 and Th2 activation. The inability of young adult male SJL mice to activate Th1 cells was reversed via depletion of NK1.1(+) cells, whereas the presence or the absence of NK1.1(+) cells did not alter responses in age-matched females. Consistent with a gender-dependent role in regulating adaptive immunity, significantly more NK1.1(+) cells were present in males compared with females, and this difference was reversed by castration. In contrast to NK1.1(+) cells derived from C57BL/6 mice, no spontaneous cytokine secretion was detected in NK1.1(+) cells derived from either male or female SJL mice, although an increased frequency of IL-10-secreting NK1.1(+) cells was observed in males vs females following in vitro stimulation. Direct evidence that NK1.1(+) cells in males influence CD4(+) T cell activation before Ag exposure was demonstrated via the adoptive transfer of APC from control and NK1.1-depleted males. The absence of a functional NK T cell population in SJL mice suggests that NK cells influence adaptive immunity before Ag exposure via alterations in APC activity.     

Characterization of a heparan sulfate 3-O-sulfotransferase-5, an enzyme synthesizing a tetrasulfated disaccharide

Heparan sulfate d-glucosaminyl 3-O-sulfotransferases (3-OSTs) catalyze the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to position 3 of the glucosamine residue of heparan sulfate and heparin. A sixth member of the human 3-OST family, named 3-OST-5, was recently reported (Xia, G., Chen, J., Tiwari, V., Ju, W., Li, J.-P., Malmstrom, A., Shukla, D., and Liu, J. (2002) J. Biol. Chem. 277, 37912-37919). In the present study, we cloned putative catalytic domain of the human 3-OST-5 and expressed it in insect cells as a soluble enzyme. Recombinant 3-OST-5 only exhibited sulfotransferase activity toward heparan sulfate and heparin. When incubated heparan sulfate with [35S]PAPS, the highest incorporation of35S was observed, and digestion of the product with a mixture of heparin lyases yielded two major35S-labeled disaccharides, which were determined as DeltaHexA-GlcN(NS,3S,6S) and DeltaHexA(2S)-GlcN(NS,3S) by further digestion with 2-sulfatase and degradation with mercuric acetate. However, when used heparin as acceptor, we identified a highly sulfated disaccharide unit as a major product. This had a structure of DeltaHexA(2S)-GlcN(NS,3S,6S). Quantitative real-time PCR analysis revealed that 3-OST-5 was highly expressed in fetal brain, followed by adult brain and spinal cord, and at very low or undetectable levels in the other tissues. Finally, we detected a tetrasulfated disaccharide unit in bovine intestinal heparan sulfate. To our knowledge, this is the first report to describe not only the natural occurrence of tetrasulfated disaccharide unit but also the enzymatic formation of this novel structure.     

MiR-126 acts as a tumor suppressor in pancreatic cancer cells via the regulation of ADAM9

The epithelial-mesenchymal transition (EMT) is a critical step for pancreatic cancer cells as an entry of metastatic disease. Wide variety of cytokines and signaling pathways are involved in this complex process while the entire picture is still cryptic. Recently, miRNA was found to regulate cellular function including EMT by targeting multiple mRNAs. We conducted comprehensive analysis of miRNA expression profiles in invasive ductal adenocarcinoma (IDA), intraductal papillary mucinous adenoma, intraductal papillary mucinous carcinoma, and human pancreatic cancer cell line to elucidate essential miRNAs which regulate invasive growth of pancreatic cancer cells. Along with higher expression of miR-21 which has been shown to be highly expressed in IDA, reduced expression of miR-126 in IDA and pancreatic cancer cell line was detected. The miR-126 was found to target ADAM9 (disintegrin and metalloproteinase domain-containing protein 9) which is highly expressed in pancreatic cancer. The direct interaction between miR-126 and ADAM9 mRNA was confirmed by 3' untranslated region assay. Reexpression of miR-126 and siRNA-based knockdown of ADAM9 in pancreatic cancer cells resulted in reduced cellular migration, invasion, and induction of epithelial marker E-cadherin. We showed for the first time that the miR-126/ADAM9 axis plays essential role in the inhibition of invasive growth of pancreatic cancer cells.     

Allelic variants of human calcitonin receptor in the Japanese population

Evidence from cDNA cloning has shown that calcitonin receptors (CTRs) have seven potential transmembrane domains. In this study, structural analysis of CTRs from ten cultured human tumor cell lines and 117 human blood samples demonstrated allelic variants at the 1377th nucleotide in intracellular domain 4, expressing either proline or leucine as the 463rd amino acid. It was found that the variant with proline at this site was the more prevalent type of CTR among the Japanese population. Received: 21 June 1996     

The photosynthetic capacity of pea leaves with a controlled chlorophyll formation

Summary The relationship between chlorophyll content and photosynthesis as measured in whole leaves by CO₂ uptake and by the component reactions of the electron transport chain of isolated chloroplasts, has been investigated. Leaves with a retarded chlorophyll formation, brought about by treatment with chloramphenicol, terramycin or by a low light intensity, were compared with control leaves (i) illuminated for a similar period of time, and (ii) with a similar chlorophyll content. There appeared to be no direct relationship between chlorophyll content and photosynthetic rate. It is suggested that CO₂ uptake in low light treated leaves was limited by lack of enzymes, which are formed as a response to the supply of photosynthetic products. With terramycin and chloramphenicol the limiting factors may also be lowered enzyme levels, caused by specific protein synthesis inhibition. It is suggested that a component of Light System II required a high light intensity stimulation, and its formation was inhibited by chloramphenicol. The synthesis of a substance linking Light Systems I and II appears to be closely associated with chlorophyll formation, and could well be plastoquinone. Structural damage to the intermediate chain between Light Systems I and II is also apparently induced by chloramphenicol.The following abbreviations are used ADP adenosine diphosphate - ATP adenosine triphosphate - CMU 3 (3-chlorophenyl)-l, l-dimethylurea; DCIP dichlorophenol indophenol - NADP nicotinamide adenine dinucleotide phosphate - PMS phenazine methosulphate - TRIS 2-amino-2-hydroxymethyl propane-l, 3-diol This work was supported by a Science Research Council studentship granted to R. J. Dowdell and submitted for the degree of Ph. D. of Bath University of Technology.