FIGURE 6.

Obesity-mediated endoplasmic reticulum (ER) stress underlies cardiometabolic disorders: Obesity induces certain conditions such as hyperglyceridemia, glycemia, insulin resistance, and macrophage activation, all of which, in turn switches on several pathways culminating in ER stress, inflammation, and ultimately cardiometabolic disorders. Insulin resistance induces ER stress, which activates three branches of unfolded protein response (UPR) including ATF6, PERK, and IRE-1α. IRE-1α/TRAF2/JNK1/c-Jun pathway induces inflammation via TNF-α and IL-6, while PERK/eIF2α/IκBα pathway and ATF6 trigger NF-κB complex-mediated inflammation. Macrophage also produces IL-1β, which activates IKK and NF-κB complexes leading to inflammation. Hyperglyceridemia and glycemia induce carbotoxicity and lipotoxicity, which instigates metabolic alterations resulting in ER stress and inflammation. IRE-1α, inositol-requiring protein-1; PERK, protein kinase RNA-like ER kinase; ATF6, activating transcription factor-6; IKK, I-κb-kinase; NF-κB, nuclear factorκB; IκBα, I-κb-α; Ub, ubiquitin; eIF2α, eukaryotic initiation factor 2α; Nrf-2, nuclear factor-E2-related factor; XBP1s, X-box-binding-protein-1 spliced; TRAF2, TNF receptor-associated factor 2; JNK1, C-Jun NH₂-terminal kinase 1; ATF4, activating transcription factor-4; FOXO, forkhead box O; c-Jun, a transcription factor; CHOP, C/EBP homologous protein; FA, fatty acid; Glu, glucose; GLUT4, glucose transporter type 4; DAG, diacylglycerol; O-GlcNAc, β-linked N-acetylglucosamine; AGEs, advanced glycation end-products.