Rafting on the Evidence for Lipid Raft-like Domains as Hubs Triggering Environmental Toxicants’ Cellular Effects

Abstract

The plasma membrane lipid rafts are cholesterol- and sphingolipid-enriched domains that allow regularly distributed, sub-micro-sized structures englobing proteins to compartmentalize cellular processes. These membrane domains can be highly heterogeneous and dynamic, functioning as signal transduction platforms that amplify the local concentrations and signaling of individual components. Moreover, they participate in cell signaling routes that are known to be important targets of environmental toxicants affecting cell redox status and calcium homeostasis, immune regulation, and hormonal functions. In this work, the evidence that plasma membrane raft-like domains operate as hubs for toxicants’ cellular actions is discussed, and suggestions for future research are provided. Several studies address the insertion of pesticides and other organic pollutants into membranes, their accumulation in lipid rafts, or lipid rafts’ disruption by polychlorinated biphenyls (PCBs), benzo[a]pyrene (B[a]P), and even metals/metalloids. In hepatocytes, macrophages, or neurons, B[a]P, airborne particulate matter, and other toxicants caused rafts’ protein and lipid remodeling, oxidative changes, or amyloidogenesis. Different studies investigated the role of the invaginated lipid rafts present in endothelial cells in mediating the vascular inflammatory effects of PCBs. Furthermore, in vitro and in vivo data strongly implicate raft-localized NADPH oxidases, the aryl hydrocarbon receptor, caveolin-1, and protein kinases in the toxic mechanisms of occupational and environmental chemicals.

Cardiolipin Membranes Promote Cytochrome c Transformation of Polycyclic Aromatic Hydrocarbons and Their In Vivo Metabolites

“…In cells, low levels of BaP were enough to affect the mitochondrial membrane potential and ATP levels [ 18 ]. In other studies, air particulate matter was detected inside cells associated with membrane structures like mitochondria [ 19 ], and lipophilic PAHs effectively incorporated into phospholipid membranes [ 20 , 21 ], including those containing cardiolipin (CL), a phospholipid characteristic of bacterial and mitochondrial membranes [ 22 ]. Hence, PAHs and their metabolites in cells are probably available to interact with mitochondrial components, especially with membrane-associated lipids and proteins.…”