Epigenetic regulation of HYAL-1 hyaluronidase expression. identification of HYAL-1 promoter.

HYAL-1 (hyaluronoglucosaminidase-1) belongs to the hyaluronidase family of enzymes that degrade hyaluronic acid. HYAL-1 is a marker for cancer diagnosis and a molecular determinant of tumor growth, invasion, and angiogenesis. The regulation of HYAL-1 expression is unknown. Real time reverse transcription-PCR using 11 bladder and prostate cancer cells and 69 bladder tissues showed that HYAL-1 mRNA levels are elevated 10-30-fold in cells/tissues that express high hyaluronidase activity. Although multiple transcription start sites (TSS) for HYAL-1 mRNA were detected in various tissues, the major TSS in many tissues, including bladder and prostate, was at nucleotide 27274 in the cosmid clone LUCA13 (AC002455). By analyzing the 1532 base sequence 5' to this TSS, using cloning and luciferase reporter assays, we identified a TACAAA sequence at position -31 and the minimal promoter region between nucleotides -93 and -38. Mutational analysis identified that nucleotides -73 to -50 (which include overlapping binding consensus sites for SP1, Egr-1, and AP-2), bases C(-71) and C(-59), and an NFkappaB-binding site (at position -15) are necessary for promoter activity. The chromatin immunoprecipitation assay identified that Egr-1, AP-2, and NFkappaB bind to the promoter in HYAL-1-expressing cells, whereas SP1 binds to the promoter in non-HYAL-1-expressing cells. 5-Aza-2'-deoxycytidine treatment, bisulfite DNA sequencing, and methylation-specific PCR revealed that HYAL-1 expression is regulated by methylation at C(-71) and C(-59); both Cs are part of the SP1/Egr-1-binding sites. Thus, HYAL-1 expression is epigenetically regulated by the binding of different transcription factors to the methylated and unmethylated HYAL-1 promoter.

Solution structure of the complex between poxvirus-encoded CC chemokine inhibitor vCCI and human MIP-1beta.

Chemokines (chemotactic cytokines) comprise a large family of proteins that recruit and activate leukocytes, giving chemokines a major role in both immune response and inflammation-related diseases. The poxvirus-encoded viral CC chemokine inhibitor (vCCI) binds to many CC chemokines with high affinity, acting as a potent inhibitor of chemokine action. We have used heteronuclear multidimensional NMR to determine the structure of an orthopoxvirus vCCI in complex with a human CC chemokine, MIP-1beta (macrophage inflammatory protein 1beta). vCCI binds to the chemokine with 1:1 stoichiometry, forming a complex of 311 aa. vCCI uses residues from its beta-sheet II to interact with a surface of MIP-1beta that includes residues adjacent to its N terminus, as well as residues in the 20's region and the 40's loop. This structure reveals the strategy used by vCCI to tightly bind numerous chemokines while retaining selectivity for the CC chemokine subfamily.

Glycosaminoglycan disaccharide alters the dimer dissociation constant of the chemokine MIP-1 beta.

Chemokines are immune system proteins that recruit and activate leukocytes to sites of infection. This recruitment is believed to involve the establishment of a chemokine concentration gradient by the binding of chemokines to glycosaminoglycans (GAGs). In previous studies, we elucidated the GAG binding site of the chemokine MIP-1beta and implicated the involvement of the chemokine dimer in GAG binding through residues across the dimer interface. In the present studies, nuclear magnetic resonance spectroscopy was used to investigate the effect of GAG binding on MIP-1beta dimerization. Using several dimerization-impaired variants of MIP-1beta (F13Y, F13L, L34W, and L34K), these studies indicate that the addition of disaccharide to the mutants increases their dimerization affinities. For MIP-1beta F13Y, the presence of the disaccharide increases the chemokine dimerization affinity about 9-fold as evidenced by a decrease in the dimer dissociation constant from 610 to 66 microM. Even more dramatically, the dimerization affinity of MIP-1beta L34W also increases upon addition of disaccharide, with the dimer dissociation constant decreasing from 97 to 6.5 microM. After this effect for the mutants of MIP-1beta was shown, similar experiments were conducted with the CC chemokine RANTES, and it was demonstrated that the presence of disaccharide increases its dimerization affinity by almost 7-fold. These findings provide further evidence of the importance of the dimer in chemokine function and provide the first quantitative investigation of the role of GAGs in the manipulation of the MIP-1beta quaternary structure.

The binding surface and affinity of monomeric and dimeric chemokine macrophage inflammatory protein 1 beta for various glycosaminoglycan disaccharides.

Chemokines comprise a family of proteins that function in the immune response to recruit leukocytes to sites of infection. This recruitment is believed to be carried out by the establishment of a chemokine gradient by the binding of chemokines to sulfated polysaccharides known as glycosaminoglycans (GAGs) located on the extracellular surface of endothelial cells. In the present studies, multidimensional NMR spectroscopy was used to study the interaction of monomeric and dimeric chemokine macrophage inflammatory protein (MIP)-1 beta variants with a series of differentially sulfated disaccharides. The data define a GAG binding surface, including both basic and uncharged residues such as Arg(18), Asn(23), Val(25), Thr(44), Lys(45), Arg(46), and Ser(47). Dissociation constants determined from these NMR studies consistently show for each disaccharide that dimeric wild type MIP-1 beta binds more tightly than monomeric MIP(9). Furthermore, analysis of the binding surface suggests that participation in the dimer of residues Met(3), Gly(4), and Ser(5) may be responsible for this higher affinity. These studies also indicate that the specificity of MIP-1 beta for particular GAG disaccharides is directly related not only to the degree of disaccharide sulfation but also to the position of the sulfate moiety, with O-sulfation at position 2 of the hexuronic acid unit and position 6 of the D-glucosamine being major determinants for binding.