Scientific Report 2003-2004 - Cleveland Clinic Lerner Research ...

THE HAMILTONLABORATORYPROJECT SCIENTISTSRoopa Biswas, Ph.D.Julie Tebo, Ph.D.POSTDOCTORAL FELLOWSYalei Dai, Ph.D.Shyamasree Datta, Ph.D.TECHNICAL ASSOCIATESAlison ChudykCarol CrooksJennifer MajorMichael NovotnyThe diversity of the inflammatory process stemsfrom multiple sources, including the collectionof cell types that participate, the nature andcomplexity of the inflammatory stimulus, thetransmembrane and intracellular signaling processesthat occur following stimulation, and the largenumber of independently regulated genes whoseexpression is subject to modulation during theprocess. Our research program is focused upondefining the molecularevents that control theexpression of induciblegenes during responsesto multiple forms ofstimulation. Thesestudies focus uponalterations in transcriptionaland posttranscriptionalactivitiesthat can producesignificant changes inlevels of inflammatorygene products.We have focusedattention on theregulation ofchemoattractant cytokine(chemokine) geneexpression in mononuclearphagocytes andother cell types thatparticipate in inflammatoryresponses. Thespecific genes we haveutilized include theinterferon-inducibleprotein (IP)-10 and themonokine induced by interferon-γ (Mig) chemokines,critical determinants of activated T-cell recruitmentto sites of antigen-driven immune response, and theELR-CXC chemokines KC and macrophageinflammatory protein-2 (MIP-2), which targetThe Department of ImmunologyRegulation of Inflammatory ChemokineGene ExpressionThomas A. Hamilton, Ph.D.neutrophils during the early inflammatory response toinjury and infection. In each case, the sequenceregions controlling transcription for each gene havebeen characterized, as have sequences within themRNA bodies that contribute to post-transcriptionalcontrol of mRNA stability.Although the mechanisms that increasechemokine gene expression are important, it is equallynecessary to provide negative regulation of theseinflammation-generatinggenes, as over-expressionhas the potential to producesubstantial tissue injury. Toexamine this process, wehave studied the mechanismsinvolved in suppressionof IFN-β- or LPSinducedgene expression byanti-inflammatory cytokines,including interleukin-4 and-10 and transforminggrowth factor-β. Someinhibitory effects aremediated at the level oftranscription and appear toinvolve the sequestration ofnecessary co-activators,whereas others involvemodulation of mRNAdecay.The goals of currentprojects include (1)determination of mechanismsassociated with IL-4mediated, STAT6 dependentand independent suppressionof inflammatory genetranscription, (2) the definition of mechanismsthrough which mRNA decay is achieved andregulated, and (3) the importance of specifictranscriptional and post-transcriptional mechanismsfor control of inflammatory gene expression in vivo.Hamilton, T.A., Ohmori, Y., and J. Tebo (2002) Regulation of chemokine expression by antiinflammatorycytokines. Immunol. Res. 25:229-245.Endlich, B., Armstrong, D., Brodsky, J., Novotny, M., and T.A. Hamilton (2002) Distinct temporal patterns ofmacrophage-inflammatory protein-2 and KC chemokine gene expression in surgical injury. J. Immunol.168:3586-3594.Toshchakov, V., Jones, B.W., Perera, P.-Y., Thomas, L., Cody, J., Williams, B., Major, J., Hamilton, T.A.,,Fenton, M.J., and S.N. Vogel (2002) TLR4, but not TLR2, mediates IFN-beta-induced STAT1alpha/betadependentgene expression in macrophages Nat. Immunol. 3:392-398.Major, J., Fletcher, J.E., and T.A. Hamilton (2002) IL-4 pretreatment selectively enhances cytokine andchemokine production in lipopolysaccharide-stimulated mouse peritoneal macrophages. J. Immunol. 168:2456-2463.Tebo, J., Der, S., Frevel, M., Khabar, K.S., Williams, B.R., and T.A. Hamilton (2003) Heterogeneity in controlof mRNA stability by AU rich elements. J. Biol. Chem. 278:12085-12093.92