Selenium-Encoded Isotopic Signature Targeted Profiling

Abstract

Selenium (Se), as an essential trace element, plays crucial roles in many organisms including humans. The biological functions of selenium are mainly mediated by selenoproteins, a unique class of selenium-containing proteins in which selenium is inserted in the form of selenocysteine. Due to their low abundance and uneven tissue distribution, detection of selenoproteins within proteomes is very challenging, and therefore functional studies of these proteins are limited. In this study, we developed a computational method, named as selenium-encoded isotopic signature targeted profiling (SESTAR), which utilizes the distinct natural isotopic distribution of selenium to assist detection of trace selenium-containing signals from shotgun-proteomic data. SESTAR can detect femtomole quantities of synthetic selenopeptides in a benchmark test and dramatically improved detection of native selenoproteins from tissue proteomes in a targeted profiling mode. By applying SESTAR to screen publicly available datasets from Human Proteome Map, we provide a comprehensive picture of selenoprotein distributions in human primary hematopoietic cells and tissues. We further demonstrated that SESTAR can aid chemical-proteomic strategies to identify additional selenoprotein targets of RSL3, a canonical inducer of cell ferroptosis. We believe SESTAR not only serves as a powerful tool for global profiling of native selenoproteomes, but can also work seamlessly with chemical-proteomic profiling strategies to enhance identification of target proteins, post-translational modifications, or protein–protein interactions.

Selenoproteome Identification in Inflamed Murine Primary Bone Marrow-Derived Macrophages by Nano-LC Orbitrap Fusion Tribrid Mass Spectrometry

“…A combination of shotgun proteomic workflow and LA-ICP-MS method identified eight non-Sec containing peptides for Gpx3 and seven peptides for selenoprotein P (Selenop) with a good MS/MS spectrum that matched well with the National Institute of Standards and Technology peptide mass spectral library in depleted human plasma, where human Standard Reference Material 1950 was used [29,30]. In a recent study, Se-encoded isotopic signature targeted profiling (SESTAR) computational method was developed to detect selenoproteins by utilizing the distinct natural isotopic distribution of Se that demonstrated the natural distribution across different cell lines and tissues [31].…”

GPX4 at the Crossroads of Lipid Homeostasis and Ferroptosis

“…Direct inhibition of GSH biosynthesis, or genetic manipulations that lead to lower steady‐state intracellular GSH levels, can also trigger or sensitize to ferroptosis . By contrast, 1 S ,3 R ‐RSL3 (hereafter RSL3), and related molecules, covalently inactivate GPX4 by binding to the active site selenocysteine . GPX4 protein expression and/or activity can also be inhibited indirectly by the small molecules FIN56 and FINO 2 , through mechanisms that remain only partially characterized …”

Modulation of ferroptosis sensitivity by TXNRD1 in pancreatic cancer cells

“…[10][11][12][13] This Cterminal selenocysteine operates alongside NADPH and FAD domains to reduce oxidized species. 14 The unique enzyme structure of TXNRD1, combined with the reactivity of its selenocysteine residue toward smallmolecule electrophiles, [15][16][17][18] warrants careful consideration when dissecting the function of TXNRD1 through genetic versus pharmacological inhibition. Inhibition of TXNRD1 has been previously explored as a therapeutic approach through which to kill cancer cells possessing a heightened dependence on resolving oxidative stress.…”