Characterization of cardiolipins and their oxidation products by LC–MS analysis

Abstract

Cardiolipins, a class of mitochondria-specific lipid molecules, is one of the most unusual and ancient phospholipids found in essentially all living species. Typical of mammalian cells is the presence of vulnerable to oxidation polyunsaturated fatty acid resides in CL molecules. The overall role and involvement of cardiolipin oxidation (CLox) products in major intracellular signaling as well as extracellular inflammatory and immune responses have been established. However, identification of individual peroxidized molecular species in the context of their ability to induce specific biological responses has not been yet achieved. This is due, at least in part, to technological difficulties in detection, identification, structural characterization and quantitation of CLox associated with their very low abundance and exquisite diversification. This dictates the need for the development of new methodologies for reliable, sensitive and selective analysis of both CLox. LC-MS-based oxidative lipidomics with high mass accuracy instrumentation as well as new software packages are promising in achieving the goals of expedited and reliable analysis of cardiolipin oxygenated species in biosamples.

Inactivation of the ferroptosis regulator Gpx4 triggers acute renal failure in mice

“…In an untargeted approach, we set out to directly assess lipid oxidation products in Gpx4-null kidneys using lipid extraction and LC–MS analysis 22 . These investigations were deemed necessary to bypass the use of fluorescence-based redox sensors, whose mode-of-actions are poorly characterized and may lead to potentially misleading conclusions.…”

Known unknowns of cardiolipin signaling: The best is yet to come

“…Recent developments in soft ionization techniques and mass spectrometry (MS) have provided better insights into the identification and characterization of diverse CL species in biological systems [32]. Most protocols currently used for MS analysis of CL consist of two stages.…”

“…The mitochondrial CL differs from its prokaryotic precursor by having diverse polyunsaturated acyl side chains. In addition to structurally altering the membrane bilayer, polyunsaturated acyls are also oxidation targets giving rise to myriads of signaling lipid mediators [32] The initially synthesized nascent mitochondrial CLs may include a variety of acyls (32 fatty acid residues in Lipid Maps (www.lipidmaps.org) generating a highly diversified molecular speciation of CLs. In several tissues, however, the nascent CLs with different acyls (hetero-acylated CLs) undergo subsequent synthetic transformations - a process also called remodeling - to form CLs with identical acyls, homo-acylated CLs [33-36].…”

Oxidative Lipidomics Coming of Age: Advances in Analysis of Oxidized Phospholipids in Physiology and Pathology

“…However, adjustment of the solvent systems with ionization modifiers can enable detection in the opposite ionization mode if required: for example, although PC has a constitutive positive charge on the choline moiety, phosphocholine-containing lipids can be observed in negative ion mode as formate or acetate adducts (20). As PC is both very abundant and easily observable in either mode, much research had previously focused on identifying oxidation products of unsaturated PCs (20,116), although to address this knowledge gap increasing studies on oxidation of phopholipids with other headgroups are being undertaken, including PE, PS, and CL (26,70,74,132). The principles of fatty acyl group oxidation are common to all the phospholipids, and it is well established that hydroperoxides, hydroxides, epoxides, and chlorinated species can be detected, according to the mass increments and fragmentation patterns.…”