Characterization of Intracellular Peptides from Zebrafish (Danio rerio) Brain

Abstract

Peptides represent a large class of cell signaling molecules, and they are mainly produced by the classical secretory pathway or during protein degradation. The peptide profile of Danio rerio (zebrafish) shows a lack of information when compared with other consolidated animal models. The aim of this work was to characterize the peptide profile of zebrafish brain by using triplex reductive methylation of amines labeling and liquid chromatography coupled to electron spray mass spectrometry. A total of 411 peptide fragments were detected and 125 peptide sequences could be solved. Further analysis suggested that most of the peptides were fragments of intracellular cytosolic and mitochondrial proteins, and that 60% of the precursor proteins were cleaved at either their Nor C-terminal. The most common residue in the P1 position was leucine whereas other common residues were lysine, alanine, arginine, and phenylalanine. Rare cleavage sites at P1 position were histidine, glutamic acid, and isoleucine. The peptide profile of zebrafish brain has similarities with results previously described in mice brain peptidome studies. Thus, this study represents an important basis for the molecular understanding of zebrafish and its use as a model for human diseases.

Effect of Protein Denaturation and Enzyme Inhibitors on Proteasomal-Mediated Production of Peptides in Human Embryonic Kidney Cells

“…This effect was rapid, occurring within 1 h of treatment, indicating that the pool of intracellular peptides is highly dynamic. Recently, a number of peptides derived from intracellular proteins were identified in yeast [31] and zebrafish [48], with many similarities between the peptides in these organisms and those found in different human and mouse cell lines [20,25].…”

Intracellular Peptides in Cell Biology and Pharmacology

“…Taken together, these data suggested for the first time that extra-lysosomal proteolysis by proteasomes and oligopeptidases could produce novel functional peptides, which may modulate protein interactions within cells [19]. Further studies using electron spray mass spectrometry and peptidomics techniques corroborated these initial findings, and thousands of novel intracellular peptides have now been identified in plants [20,21], yeast [22], zebrafish [23], rodents [24,25,26], human cell lines [27,28,29], and human tissues [30,31]. It is worth to mention that MHC proteins and immunoproteasomes emerge later in evolution than regular proteasomes [32].…”

Peptides from Natural or Rationally Designed Sources Can Be Used in Overweight, Obesity, and Type 2 Diabetes Therapies

“…The seminal identification of intracellular peptides was based on a substrate-capture assay that employs catalytically inactive forms of either thimet oligopeptidase (EC3.4.24.15; EP24.15, THOP1) or neurolysin (EC3.4.24.16; Nln) to identify novel pharmacological active peptides such as rat hemopressin (HP, PVNFKFLSH) and AGHLDDLPGALSAL (AGH) [44,49,50]. More recently, identifying intracellular peptides from biological samples has been performed directly from tissue or cells homogenates [51], and the rapid progress in this area is allowing the identification of thousands of intracellular peptides that have been sequenced in plants, yeast, zebrafish, rodents, and human cells and tissues [52].…”

“…Different treatments and/or diseases modify the relative concentration of specific intracellular peptides present inside the cells and tissues, suggesting pathophysiological functions [51,54,55]. In challenge conditions, cells start accumulating or losing specific intracellular peptides that are biologically functional in such conditions.…”