Cover Picture: Proteomics 3/2009

In this issue of Proteomics you will find the following highlighted articles: Dead end road without telomerase Eukaryotic cells can replicate without the protective telomerase at chromosomal ends but at a price: a gradual loss of chromosomal terminal repeats and, ultimately, the ability to replicate. Continued loss leads to cellular replicative senescence, instability and apoptosis. Zimmerman et al. used nanoLC/TOF‐MS to examine proteomic profiles of five tumor cell lines from four tissues which carried a telomerase suppressing DN (dominant‐negative) hTERT (human telomerase reverse transcriptase) mutation. Downregulated genes included histones H4, H3 and H2B; up‐regulated genes were histone H2A and cytokeratin CK 19. Several of these proteins are being further studied for possible roles as biomarkers for telomere‐dysfunction associated diseases. Zimmerman, S. et al., Proteomics 2009, 9 , 521–534. Unsticking the wicket O‐linked carbohydrates are one of the most frequent post‐translational modifications of eukaryotic proteins and the resultant glycopeptide one of the most difficult to analyze. With multiple attachment points, composition, and branching points, the carbohydrates obstruct isoelectric and electrophoretic focusing, yielding nondescript smudges on 2‐DE gels or mass spectra. Hanisch et al. have worked out a chemical protocol for removing most of these pesky sugars while the core protein remains intact and reversibly attached to a matrix compatible with automated, high‐throughput arrays. After desialylation, the glycoprotein is treated with NaIO4 for mild oxidation then cleaved with ammonia. The last two steps were repeated, leaving a product readily digested by trypsin for LC‐MS/MS analysis. Unfortunately, the de‐O‐glycosylated product is not resolved on 2‐D gels and yields an anomalously high MWon 1‐D gels for unexplained reasons. Hanisch, F.‐G. et al., Proteomics 2009, 9 , 710–719. In concert tonight: !!The Astrocytes!! Like an underground music group, astrocytes have been actively ignored for many years, consigned to a back row seat with a minor role in the development of the central nervous system. Several groups have begun to apply proteomic tools to tease out a fuller description of astrocyte functions. Here, Keene et al. detail their findings with cultured astrocytes exposed to inflammatory cytokines for one or seven days. A total of 169 secreted proteins (290 in all) were identified by gel electrophoresis/nano‐LC/MS‐MS. Gene ontology assignments were made using a number of tools to properly assign secretory/extracellular proteins. Classical morphological changes were observed as well as expected secretions (PGE2, nitric oxide, IL6). Keene, S. D. et al. , Proteomics 2009, 9 , 768–782.