The bovine cumulus proteome is influenced by maturation condition and maturational competence of the oocyte.

In vitro maturation (IVM) of oocytes has still a negative impact on the developmental competence of oocytes. Therefore, this study analysed the cumulus proteome of individual cumulus-oocyte complexes (COCs) with and without maturational competence, matured under in vivo or in vitro conditions (n = 5 per group). A novel, ultrasensitive mass spectrometry (MS) based protein profiling approach, using label-free quantification, was applied. The detected cumulus proteome included 2226 quantifiable proteins and was highly influenced by the maturation condition (479 differentially expressed proteins) as well as maturational competence of the corresponding oocyte (424 differentially expressed proteins). Enrichment analysis showed an overrepresentation of the complement and coagulation cascades (CCC), ECM-receptor interaction and steroid biosynthesis in cumulus of COCs that matured successfully under in vivo conditions. Verification of the origin of CCC proteins was achieved through detection of C3 secretion into the maturation medium, with significantly increasing concentrations from 12 (48.4 ng/ml) to 24 hours (68 ng/ml: p < 0.001). In relation, concentrations in follicular fluid, reflecting the in vivo situation, were >100x higher. In summary, this study identified important pathways that are impaired in IVM cumulus, as well as potential markers of the maturational competence of oocytes.

XBP1 mitigates aminoglycoside-induced endoplasmic reticulum stress and neuronal cell death.

Here we study links between aminoglycoside-induced mistranslation, protein misfolding and neuropathy. We demonstrate that aminoglycosides induce misreading in mammalian cells and assess endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathways. Genome-wide transcriptome and proteome analyses revealed upregulation of genes related to protein folding and degradation. Quantitative PCR confirmed induction of UPR markers including C/EBP homologous protein, glucose-regulated protein 94, binding immunoglobulin protein and X-box binding protein-1 (XBP1) mRNA splicing, which is crucial for UPR activation. We studied the effect of a compromised UPR on aminoglycoside ototoxicity in haploinsufficient XBP1 (XBP1(+/-)) mice. Intra-tympanic aminoglycoside treatment caused high-frequency hearing loss in XBP1(+/-) mice but not in wild-type littermates. Densities of spiral ganglion cells and synaptic ribbons were decreased in gentamicin-treated XBP1(+/-) mice, while sensory cells were preserved. Co-injection of the chemical chaperone tauroursodeoxycholic acid attenuated hearing loss. These results suggest that aminoglycoside-induced ER stress and cell death in spiral ganglion neurons is mitigated by XBP1, masking aminoglycoside neurotoxicity at the organismal level.

Activity-based proteomics: identification of ABHD11 and ESD activities as potential biomarkers for human lung adenocarcinoma.

Lung cancer is the leading cause of all cancer related deaths with a worldwide mortality of 1.2 million each year. The 5-year survival rate ranges from 80% in early stages to a dismal 5% in advanced disease. Prognosis is currently mostly determined based on the extension of disease at diagnosis. Thereby it has become evident that predicted and real outcomes can vary significantly, even for patients with the same stage of disease. Novel biomarkers with a reliable predictive significance are therefore clearly needed. In this study we implemented an activity-based, solely mass spectrometry dependent biomarker discovery platform. We investigated the role of serine hydrolase activities as potential biomarkers for human lung adenocarcinoma, the most common lung cancer subtype. Forty pairs of fresh frozen malignant and matching non-neoplastic lung tissues were analyzed and enzymatic activities linked to clinical follow-up data. We found that the activities of Abhydrolase domain-containing protein 11 and Esterase D predict the development of distant metastases and the presence of aggressive lung adenocarcinomas, respectively, in a statistically significant model. We conclude that serine hydrolase activities bear a predictive potential for human lung adenocarcinoma and that activity-based proteomics represents a powerful methodology in the search for novel disease biomarkers.