Expression of cyclooxygenase-2 (COX-2) is associated with the pathogenesis of inflammation and various cancers, including lung cancer. Yin Yang 1 (YY1) is a zinc-finger transcription factor that interacts with histone acetyltransferases and deacetylases for its transcriptional activity and also is involved in inflammation and tumorigenesis. We investigated whether YY1 regulates COX-2 expression. We located a possible YY1 binding site proximal to the transcription initiation site of the COX-2 promoter. Electrophoretic mobility shift assays show that YY1 bound to the putative YY1 site in vitro. To show biological relevance, we performed chromatin immunoprecipitation assays showing that lipopolysaccharide (LPS) treatment induced YY1 binding to the cognate site in the endogenous COX-2 promoter. Overexpression of YY1 in macrophages treated with either LPS or live Pseudomonas aeruginosa increased COX-2 transcriptional activity. Furthermore, YY1 enhanced COX-2 protein expression and prostaglandin D(2) production elicited by LPS treatment. Mechanistically, we observed that LPS treatment resulted in disruption of an interaction between YY1 and p300, a histone acetyltransferase, but did not affect the interaction between YY1 and histone deacetylase 1/2. These data suggest that in response to LPS, YY1 dissociates from p300 and binds to the COX-2 promoter, contributing to COX-2 expression in an inflammatory milieu.

Macrophages are an abundant source of cyclooxygenase-2 (COX-2) enzymatic products, but a specific mechanism for macrophage COX-2 gene expression has not been described. We examined whether PU.1, a myeloid-specific Ets family transcription factor, is involved. Sequence analysis revealed two potential c-Ets binding sites in the COX-2 promoter (COX-2p) which bind to immunoreactive PU.1. Chromatin immunoprecipitation analysis shows inducible PU.1 binding to these sites in response to lipopolysaccharide, and COX-2 protein production is augmented by ectopic expression of PU.1 but not by pU.1(S148A), indicating that PU.1 phosphorylation is likely involved. Interestingly, expression of PU.1 results in acetylation of CCAAT/enhancer-binding protein-beta (C/EBP-beta) and increased production of COX-2 protein. Coimmunoprecipitation experiments suggest a role for p300 in C/EBP-beta acetylation and COX-2 expression. In contrast, E1A inhibits acetylation of C/EBP-beta and is correlated with decreased COX-2 expression. Together, these data suggest that PU.1 is activated by phosphorylation of Ser(148) in response to lipopolysaccharide treatment and subsequently binds to sequences in the endogenous COX-2p in a time-dependent manner. Concomitantly, C/EBP-beta becomes acetylated, and expression of the COX-2 gene increases. We speculate that a combinatorial role of PU.1 and C/EBP-beta mediates the robust production of COX-2 products by macrophages which occurs in Gram-negative bacterial sepsis.

The nuclear factor kappa B (NF-κB) transcription factor plays a key role in the induction of pro-inflammatory gene expression, leading to the synthesis of cytokines, adhesion molecules, chemokines, growth factors and enzymes. Results of studies in in vitro and in vivo models of inflammation and malignancy have also suggested central roles for NF-κB in programmed cell death, or apoptosis.

We have measured the heats of formation of the trp repressor/operator complex by direct titration calorimetry over the temperature range 10°C to 40°C. A primary strong mode of binding displays the characteristic large negative heat capacity observed by other methods in the formation of specific protein/DNA complexes. Unlike most such reactions, however, the formation of the trp repressor/operator complex is enthalpically driven throughout the physiological temperature range. After saturation of this principal mode, we also detected a secondary weaker binding mode, which we ascribe to a now well documented interaction called "half-site" binding. Although weak, this mode also exhibits an unusually large negative heat capacity change. Since the interface of the proposed secondary half-site binding mode has the same complementary stereochemistry as the primary one (due to internal symmetry), we correlate the negative heat capacity change with the formation of a stereospecific interface and not with high affinity. As in similar cases, the empirical correlation between buried non-polar surfaces and reduction of heat capacity does not account for the large negative ΔCp, nor do crystal structures reveal any further reduction in solvent excluded surfaces within the reactants upon complex formation. We attribute the "unaccounted for" decrement in the heat capacity of the complex to the stereospecific restriction of the hydrated polar elements that form the specific interface. We suggest that the "tightening of soft internal modes" at and near the polar interface of the complex is more important than previously recognized because previous considerations did not take into account the highly hydrated nature of these polar elements and the concomitant reduction in the degrees of freedom of the water structure.

The high affinity of mercuric ion for thiolate ligands and the rapid ligand exchange rates of the resulting complexes make Hg(II) a relatively easy metal to bind to active sites of a variety of cysteine-containing enzymes. This feature has made mercuric ion a useful biochemical tool for selectively displacing one type of copper from a multicopper enzyme. It has become apparent that several spectroscopic features of Hg(II) complexes in their own right could be useful in distinguishing a variety of coordination environments. Although Hg(II) is a d10 metal, it would be a mistake to consider it spectroscopically silent. As described here, the interaction of Hg(II) with biopolymers can be probed using extended X-ray absorption fine structure (EXAFS), UV-Vis, 199Hg nuclear magnetic resonance (NMR), and circular dichroism (CD) spectroscopies. Several features in the spectra of structurally characterized model complexes have been correlated with the primary coordination number of the metal, aiding in the determination of coordination environments in proteins. This chapter discusses the advantages and limitations of using Hg(II) substitution in structure, function, and spectroscopic studies of proteins. Given these spectroscopic handles, determination of the coordination geometry, ligand identity, metal binding stoichiometry, dissociation rates, and binding constants are possible. Practical techniques, such as common methods for binding Hg(II) to proteins, are discussed. This chapter presents mercury chemistry, including structural and thermodynamic trends of biologically relevant mercury compounds.

ChemInformVolume 21, Issue 30 Physical Organic Chemistry ChemInform Abstract: Solid-State 199Hg Nuclear Magnetic Resonance as a Probe of Coordination Number and Geometry in Hg(II) Complexes. M. J. NATAN, M. J. NATAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorC. F. MILLIKAN, C. F. MILLIKAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorJ. G. WRIGHT, J. G. WRIGHT Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorT. V. O'HALLORAN, T. V. O'HALLORAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this author M. J. NATAN, M. J. NATAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorC. F. MILLIKAN, C. F. MILLIKAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorJ. G. WRIGHT, J. G. WRIGHT Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this authorT. V. O'HALLORAN, T. V. O'HALLORAN Dep. Chem., Northwest. Univ., Evanston, IL 60208, USASearch for more papers by this author First published: July 24, 1990 https://doi.org/10.1002/chin.199030039Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue30July 24, 1990 RelatedInformation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolid-state mercury-199 nuclear magnetic resonance as a probe of coordination number and geometry in Hg(II) complexesMichael J. Natan, Clark F. Millikan, Jeffrey G. Wright, and Thomas V. O'HalloranCite this: J. Am. Chem. Soc. 1990, 112, 8, 3255–3257Publication Date (Print):April 1, 1990Publication History Published online1 May 2002Published inissue 1 April 1990https://pubs.acs.org/doi/10.1021/ja00164a080https://doi.org/10.1021/ja00164a080research-articleACS PublicationsRequest reuse permissionsArticle Views196Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

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