Redox/Ferroptosis Antibody Sampler Kit #70703

Apoptosis-inducing factor mitochondria-associated 2 (AIFM2) is a homolog of apoptosis-inducing factor (AIF) (1,2). Research studies show that it inhibits ferroptosis. Therefore, this protein was named ferroptosis suppressor protein 1 (FSP1). FSP1 is a coenzyme Q₁₀ (CoQ) oxidoreductase and generates the reduced form of CoQ, which traps lipid peroxides, leading to the suppression of ferroptosis. Furthermore, inhibition of ferroptosis by FSP1 was shown to be independent of glutathione peroxidase 4 (GPX4), another negative regulator of ferroptosis (3,4).

The selenoprotein GPX4 is a master regulator of ferroptosis, a form of programmed cell death induced by iron-dependent lipid peroxidation (3,5). GPX4 converts lipid hydroperoxides to non-toxic lipid alcohols, preventing ferroptosis (3). Research studies show that selenium enhances GPX4 expression and inhibits ferroptotic death to protect neurons (6). In addition, some therapy-resistant cancer cells depend on GPX4 to survive. Loss of GPX4 leads to ferroptosis, preventing tumor relapse in mice (7). Furthermore, redox homeostasis mediated by GPX4 is essential for activating the cytosolic DNA-sensing cGAS-STING pathway and initiating the subsequent innate immune response (8).

Cytochrome P450 oxidoreductase (POR), also known as CYPOR, is a diflavin reductase that uses flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) as cofactors and nicotinamide adenine dinucleotide phosphate (NADPH) as an electron donor (9). Cytochrome P450 is a family of heme-containing enzymes functioning as monooxygenases, oxidizing steroids, fatty acids, drugs, and xenobiotics. These enzymes depend on POR for electron supply. In addition, POR donates electrons to heme oxygenase and cytochrome b5 and c. In addition to its various roles in drug and steroid metabolism, studies have found that POR contributes to lipid peroxidation during ferroptosis (10-12).

Thioredoxin is a small redox protein found in many eukaryotes and prokaryotes. Multiple forms of thioredoxin have been identified, including cytosolic thioredoxin 1 (TRX1) and mitochondrial thioredoxin 2 (TRX2) (13).

Arachidonic acid 12-lipoxygenase (ALOX12) is an important lipoxygenase that specifically converts arachidonic acid into 12-hydroperoxyeicosatetraenoic acid (12- HpETE), which is then reduced by glutathione peroxidase to 12-hydroxyeicosatetraenoic acid (12-HETE) (14). ALOX12 inhibition abrogates p53-mediated ferroptosis and tumor suppression but does not affect other ferroptosis pathways, such as that driven by GPX4 (15).

Polyunsaturated fatty acid lipoxygenase ALOX15 catalyzes oxygenation of polyunsaturated fatty acids to corresponding hydroperoxides (16,17). Studies show that the small scaffolding protein PEBP1 associates with ALOX15 and polyunsaturated fatty acid lipoxygenase ALOX15B to change their substrate specificity, resulting in the conversion of polyunsaturated phosphatidylethanolamines (PE) to hydroperoxy-PE. Hydroperoxy-PE, when not sufficiently reduced by GPX4, causes ferroptosis (5).

Cyclooxygenase1 (Cox1) and cyclooxygenase2 (Cox2), family members with 60% homology in humans, catalyze prostaglandin production from arachidonic acid (18,19). While Cox1 expression is constitutive in most tissues, Cox2 expression is induced by lipopolysaccharide (LPS) and peptidoglycan (PGN) (20).

The nuclear factor-like 2 (NRF2) transcriptional activator binds antioxidant response elements (ARE) of target gene promoter regions to regulate expression of oxidative stress response genes. Under basal conditions, the NRF2 inhibitor INrf2 (also called KEAP1) binds and retains NRF2 in the cytoplasm, where it can be targeted for ubiquitin-mediated degradation (21). Following oxidative or electrophilic stress, KEAP1 releases NRF2, allowing the activator to translocate to the nucleus and bind to ARE-containing genes (22).