Expression patterns of the phosphoproteins and total proteins in TLQP-21 (a VGF derived peptide) treated SH-SY5Y cells

VGF (non-acronymic), belonging to a large granin family, gives rise to a number of bioactive peptides by proteolysis and exert an extensive array of biological effects on energy metabolism, pain modulation, gastric secretion function, reproduction, mood regulation, and, diabetes. Among VGF-derived peptides, TLQP-21 (The first four amino acids, in short TLQP (Thr-Leu-Gln-Pro) generalizes the nomenclature of the peptide by its length) is the most studied although little is known yet about downstream molecular mechanisms of action of VGF-derived peptides like TLQP-21. So here as a preliminary analysis, total protein expression was carried out in addition to the phosphoproteomic study of SH-SY5Y cells treated with TLQP-21, using the same cell extracts. Comparison of simple 1D SDS-PAGE gels stained with SYPRO® Ruby protein gel stain was carried out to assess whether changes in protein expression could be seen even at such low separation resolution. Expression of several proteins most likely Microtubule-associated protein 1B (MW 271 kDa), Tubulin beta chain (MW 57), Tubulin beta-4B chain (MW 50), Alpha-2-macroglobulin (MW 163), etc. in TLQP-21 treated and control samples was found significantly different, indicating that the peptide TLQP-21 exerts biological effects on SH-SY5Y cells. Further studies are required to validate the identity of the modulated proteins, obtained from mass spectrometry. Identification of modulated proteins after TLQP-21 treatment would open new avenues to explore the molecular mechanisms of its physiological actions, and of pharmacological modulation thereof.