Identification and partial characterization of the enzyme of omega: one of five putative DPP IV genes in Drosophila melanogaster.

The omega (ome) gene product is a modifier of larval cuticle protein 5 and its alleles (and duplicates) in the third instar of Drosophila melanogaster. Using deletion mapping the locus mapped to 70F-71A on the left arm of chromosome 3. A homozygote null mutant (ome 1) shows a pleiotropic phenotype that affected the size, developmental time of the flies, and the fertility (or perhaps the behavior) of homozygous mutant males. The omega gene was verified as producing a dipeptidyl peptidase IV (DPPIV) by genetic analysis, substrate specificity and pH optimum. The identity of the gene was confirmed as CG32145 (cytology 70F4) in the Celera Database (Berkeley Drosophila Genome Project), which is consistent with its deletion map position. The genomic structure of the gene is described and the decrease in DPPIV activity in the mutant ome1 is shown to be due to the gene CG32145 (omega). The D. melanogaster omega DPPIV enzyme was partially purified and characterized. The exons of the ome1 mutant were sequenced and a base substitution mutation in exon 4 was identified that would yield a truncated protein caused by a stop codon. A preliminary study of the compartmentalization of the omega DPPIV enzyme in several organs is also reported.

Native and modified C-reactive protein bind different receptors on human neutrophils.

Native C-reactive protein (CRP) is a planar pentamer of identical subunits expressed at high serum levels during the acute phase of inflammation. At inflammatory sites, an isomeric form termed modified CRP (mCRP) is expressed and reveals neoantigenic epitopes associated with modified monomeric CRP subunits. mCRP cannot assume the native pentameric conformation but rather forms a nonpentameric aggregate of monomers. While native CRP inhibits neutrophil movement in vitro and in vivo, the effect of mCRP on neutrophil movement has not been reported. To model the biological function and biochemical interaction of mCRP on neutrophils, in vitro chemotaxis and binding experiments were performed using mCRP. Reported here, mCRP effectively inhibited fMLP-induced chemotaxis similar to native CRP. Additionally, mCRP increased binding of labeled native CRP to neutrophils. This increased binding occurred by direct protein-protein interaction of the C-terminus thereby implicating the CRP(199-206) sequence. Binding of mCRP to neutrophils was blocked by anti-CD16 monoclonal antibody whereas native CRP was not. These results suggest that modified forms of CRP inhibit chemotaxis, a function similar to native CRP, but that mCRP and native molecule bind different receptors on human neutrophils.

Suradista NSC 651016 inhibits the angiogenic activity of CXCL12-stromal cell-derived factor 1alpha.

CXCL12 (stromal cell-derived factor 1alpha), a ligand for CXCR4, has been shown to induce endothelial cell chemotaxis and to stimulate angiogenesis, suggesting that it may be a significant target for antiangiogenic therapy. Here we have tested suradista NSC 651016, a compound known to inhibit CXCL12-induced monocyte chemotaxis, for its ability to inhibit CXCL12-induced angiogenic activity. NSC 651016 inhibited CXCL12-mediated endothelial cell chemotaxis in a dose-dependent manner. In addition, new vessel sprouting, by both rat and chick aorta in an angiogenesis model, was inhibited. Additionally, in vitro capillary-like structure formation induced by CXCL12 was inhibited by NSC 651016. Furthermore, NSC 651016 inhibited CXCL12-mediated angiogenesis in an in vivo s.c. assay. These data indicate that suradista NSC 651016 possesses in vitro and in vivo antiangiogenic activity and has the potential to interfere with neovacularization of tumors and their metastases.