Cell-Signaling Arrays

Houseman et al. prepared a peptide chip by Diels-Alder-mediated reaction of kinase-peptide substrates with a self-assembled monolayer of alkanethiolates on gold surface. Peptide phosphorylation was determined by incubating the peptide microarrays with c-src protein-tyrosine kinase followed by quantitation with a phos-phoryl imager. In the presence of soluble inhibitors at a range of concentrations, dose-dependent inhibition of phosphorylation against a number of peptide substrates could be determined on a single chip.  

Small molecule or peptide substrates can also be used to profile protease and other enzyme activities. Salisbury et al. described a protease-substrate microarray in which the carboxyl end of the peptide substrates was conjugated to 7-amino-4-car-bamoylmethyl coumarin, a fluorogenic compound. The conjugate was non-fluores-cent when the electron-donating group on the coumarin was attached to the peptide. Upon proteolysis, the peptide was released and the microarray spot fluoresced. Zhu et al. demonstrated that small molecule microarrays could be used to detect enzyme activities of epoxide hydrolases and phosphatases. 

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Genomic tools 31 This method takes advantage of select genomic (microarray-or PCR-based approaches) and proteomic (antibody array analysis) tools to identify the receptors for growth factors, hormones, cytokines, and other components of cell signaling pathways expressed by a culture of interest. 

Comparison of multiple phosphoproteomic endpoints for a group of samples on the array permits evaluation of the interconnected cell-signaling proteins in the sample populations. 

Senaratne W, et al. Functionalized surface arrays for spatial targeting of immune cell signaling. J Am Chem Soc 2006 128(17) 5594—5. 

The antiinflammatory effects of statins likely result from their ability to inhibit the formation of mevalonic acid. Downstream products of this molecule include not only the end product, cholesterol, but also several isoprenoid intermediates that covalently modify ( pre-nylate ) certain key intracellular signaling molecules. Statin treatment reduces leukocyte adhesion, accumulation of macrophages, MMPs, tissue factor, and other proinflammatory mediators. By acting on the MHC class II transactivator (CIITA), statins also interfere with antigen presentation and subsequent T-cell activation. Statin treatment can also limit platelet activation in some assays as well. All these results support the concept that in addition to their favorable effect on the lipid profile, statins can also exert an array of antiinflammatory and immunomodulatory actions. 

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