Effects of waterborne Cu exposure in gilthead sea bream (Sparus aurata): a proteomic approach.

Aquatic organisms may suffer from exposure to high Cu concentrations, since this metal is widely used in feed supplementation, in pesticide formulation and as antifouling. Chronic exposure to Cu, even at sub-lethal doses, may strongly affect fish physiology. To date, several biomarkers have been used to detect Cu exposure in fish producing contrasting results. Therefore, we used a proteomic approach to clarify how Cu exposure may affect the serum proteome of gilthead sea bream (Sparus aurata), since serum could be considered a good source of early-biomarkers of Cu toxicosis. For this purpose we exposed juvenile gilthead sea bream to waterborne Cu (0.5 mg/L). Our results indicate that fish tightly regulate circulating Cu levels, which are not affected by metal exposure. This homeostatic control is mainly achieved by the liver, able to excrete high amounts of the metal via bile. Cu exposure caused differential expression of several serum proteins, 10 of which were identified by Mascot and BLAST search. All these proteins, with the exception of growth hormone receptor and γ-glutamyl-carboxylase, can be related to: 1) Cu-induced hepatotoxicity (cytochrome oxidase subunit I, alanine aminotransferase, glutathione S-transferase); 2) potential immunosuppression due to interference of Cu with the inflammation/immunity network (α-1 antitrypsin, angiotensinogen, complement component C3, recombination-activating protein-1 and warm temperature acclimation-related 65 kDa protein).

Modification of proteins secreted by endothelial cells during modeled low gravity exposure.

The exposure of the human body to microgravity, conditions that occurs during space flights, causes significant changes in the cardiovascular system. Many cell types have been involved in these changes, and the endothelium seems to play a major role. In endothelial cells (EC), it has been shown that modeled low gravity impairs nitric oxide synthesis, cell adhesion, extracellular matrix composition, cytoskeleton organization, cytokines, and growth factors secretion. Nevertheless, detailed analysis of EC physiological changes induced by microgravity exposure is still lacking. Secretome analysis is one of the most promising approaches for the identification of biomarkers directly related to the physiopathological cellular state. In this study, we analyzed in details the modifications of EC secretome by using umbilical vein endothelial (HUVE) cells exposed to modeled low gravity conditions. By adopting a two-dimensional (2-D) proteomic approach, in conjunction with a technique for the compression of the dynamic range of proteins, we observed that modeled low gravity exposure of HUVE cells affected the secretion of proteins involved in the regulation of cytoskeleton assembly. Moreover, by using Luminex® suspension array systems, we found that the low gravity condition decreased in ECs the secretion of some key pro-inflammatory cytokines, including IL-1α and IL-8, and of the pro-angiogenic factor bFGF. On the contrary, microgravity increase the secretion of two chemokines (Rantes and Eotaxin), involved in leukocytes recruitment.