An integrated transcriptomic and proteomic approach characterizing estrogenic and metabolic effects of 17 alpha-ethinylestradiol in zebrafish (Danio rerio).

Nowadays there is much concern about the presence of endocrine disrupting compounds (EDCs) in the environment due to their ability to interfere with the endocrine system. In the presented study, adult zebrafish (Danio rerio) were exposed to 30 ng L(-1) 17alpha-ethinylestradiol (EE2) for 4 and 28 days. The underlying molecular mechanisms of EE2 were studied in the zebrafish liver by applying a combined transcriptomics and proteomics approach. In addition, we assessed the added value of such an integrated-omics approach. Oligo microarrays, spotted with 3479 zebrafish-specific oligos, were employed to generate differential gene expression levels. The proteomic responses were evaluated by means of differential in-gel electrophoresis (DiGE), combined with MALDI-tandem mass spectrometry. Assessment of the major biological functions of the differentially expressed transcripts and proteins illustrated that both individual platforms could profile a clear estrogenic interference, next to numerous metabolism-related effects and stress responses. Cross-comparison of both transcriptomics and proteomics datasets displayed limited concordance, though, thorough revision of the results illustrated that transcriptional effects were projected on protein level as downstream effects of affected signalling pathways. Overall, this study demonstrated that a proteomics approach can lift the biological interpretation of microarrays to a higher level, and moreover, opens a window for identification of possible new biomarkers.

Dipeptidyl peptidase 9 (DPP9) from bovine testes: identification and characterization as the short form by mass spectrometry.

The dipeptidyl peptidases (DPP) 8 and 9 belong to the DPP4 activity and/or structure homologues (DASH). Recently, a DPP9-like protein was purified from bovine testes. The aim of the present study was to prove its identity and to investigate the characteristics of this natural enzyme. We report the identification and N-terminal sequence analysis by MALDI-TOF/TOF MS, of the purified bovine enzyme as DPP9. The tryptic peptides after in-gel digestion covered 41% and 38% of the short and full-length variants of bovine DPP9, respectively. Using Asp-N digestion combined with a very recently described mass spectrometric method using DITC glass beads, the N-terminal peptide (XTGALTSERG) was isolated. It corresponds to the N-terminus of the short form of bovine DPP9. There was no evidence for glycosylation of purified bovine DPP9. The purified DPP9 was activated and stabilized by DTT. Bovine DPP9 lost its activity almost completely after alkylation with N-ethylmaleimide. Also alkylation with iodoacetamide inhibited DPP9, albeit only 70%. Other properties of bovine DPP9 are reported, including functional stability and sensitivity towards metal ions. Our results indicate that the short form of DPP9 can be isolated from bovine testes and that it behaves as a stable enzyme suitable for further functional and biochemical characterization as well as for inhibitor screening and characterization.

Integrated proteomic analysis reveals a substantial enrichment of protein trafficking processes in hippocampus tissue after hypoxic stress.

Acute and chronic hypoxic episodes of the brain have been generally recognized as a common denominator of several neuropathologies of which cerebral ischemic stroke represents one of the leading causes of mortality and morbidity. In an attempt to clarify the plethora of molecular events elicited by ischemic or hypoxic stress, several studies have reported before on large-scale expression analysis; however, only a minority have put focus on proteome based changes. To further enrich our knowledge, we investigated the differences in protein levels following prolonged exposure of mice to global hypoxic stress in the hippocampus, one of the most susceptible regions of the brain. This was accomplished using the conventional 2-DE approach and peptide-centered quantitative methionyl-COFRADIC. Together both methods resulted in the identification of 110 unique hypoxia regulated proteins, and 34 posthypoxic reoxygenation regulated proteins based on 2-DE analysis alone. The integration and comparison of the implicated biological functions with other large-scale analyses of similar hypoxia and ischemic stroke models gave an overall resemblance of implicated biological processes apart from model specific alterations in distribution. Nevertheless, further examination of the data clearly depicted a substantial enrichment of protein trafficking and targeting processes in our data which could be related to synaptic plasticity and remodeling events.

The proteome of the human neuroblastoma cell line SH-SY5Y: an enlarged proteome.

The human neuroblastoma cell line SH-SY5Y (ATCC: CRL-2266) is widely used as a neural cellular model system. The hitherto existing proteome data (115 proteins) are here extended. A total of 1103 unique proteins of this cell line were identified using 2D-LC combined with MALDI-TOF/TOF-MS, SDS-PAGE with nano-LC-MS/MS, N-terminal COFRADIC analysis with nano-LC-MS/MS and 2D-PAGE with MALDI-TOF/TOF-MS peptide mass fingerprinting. The obtained proteome profile of this cell line is discussed.