Glutathione (GSH) is the main non-protein thiol in cells whose functions are dependent on the redox-active thiol of its cysteine moiety that serves as a cofactor for a number of antioxidant and detoxifying enzymes. While synthesized exclusively in the cytosol from its constituent amino acids, GSH is distributed in different compartments, including mitochondria where its concentration in the matrix equals that of the cytosol. This feature and its negative charge at physiological pH imply the existence of specific carriers to import GSH from the cytosol to the mitochondrial matrix, where it plays a key role in defense against respiration-induced reactive oxygen species and in the detoxification of lipid hydroperoxides and electrophiles. Moreover, as mitochondria play a central strategic role in the activation and mode of cell death, mitochondrial GSH has been shown to critically regulate the level of sensitization to secondary hits that induce mitochondrial membrane permeabilization and release of proteins confined in the intermembrane space that once in the cytosol engage the molecular machinery of cell death. In this review, we summarize recent data on the regulation of mitochondrial GSH and its role in cell death and prevalent human diseases, such as cancer, fatty liver disease, and Alzheimer’s disease.

Ribas V, Nguyen MT, Henstridge DC, Nguyen A, Beaven SW, Watt MJ, Hevener AL. Impaired oxidative metabolism and inflammation are associated with insulin resistance in ER␣-deficient mice. Am J Physiol Endocrinol Metab 298: E304 -E319, 2010. First published November 17, 2009 doi:10.1152/ajpendo.00504.2009.-Impaired estrogen action is associated with the metabolic syndrome in humans. We sought to determine whether impaired estrogen action in female C57Bl6 mice, produced by whole body Esr1 ablation, could recapitulate aspects of this syndrome, including inflammation, insulin resistance, and obesity. Indeed, we found that global knockout (KO) of the estrogen receptor (ER)␣ leads to reduced oxygen uptake and caloric expenditure compared with wild-type (WT) mice. In addition, fasting insulin, leptin, and PAI-1 levels were markedly elevated, whereas adiponectin levels were reduced in normal chow-fed KO. Furthermore, ER␣-KO mice exhibited impaired glucose tolerance and marked skeletal muscle insulin resistance that was accompanied by the accumulation of bioactive lipid intermediates, inflammation, and diminished PPAR␣, PPAR␦, and UCP2 transcript levels. Although the relative glucose intolerance and insulin resistance phenotype in KO mice became more severe with high-fat feeding, WT mice were refractory to these dietary-induced effects, and this protection coincided with a marked increase in circulating adiponectin and heat shock protein 72 levels in muscle, liver, and fat. These data indicate that ER␣ is critical for the maintenance of whole body insulin action and protection against tissue inflammation during both normal chow and high-fat feeding.estrogen receptor-␣; estrogen action; fatty acid metabolism; insulin action INSULIN RESISTANCE IS A CENTRAL FACTOR in the pathogenesis of type 2 diabetes and a defining feature of the metabolic syndrome, a constellation of abnormalities that includes obesity, hypertension, glucose intolerance, and dyslipidemia (21, 50). Prior to menopause, the incidence of type 2 diabetes is lower in women compared with men (50, 57). However, following menopause or ovariectomy this protection is lost, and a precipitous decline in insulin sensitivity coincides with increased fat mass and elevated circulating inflammatory markers [TNF␣, IL-6, and plasminogen activator inhibitor-1 (PAI-1)], LDL, triglycerides, and fatty acids (13,58,66). Similarly, alterations in estrogen receptor (ER) expression in both sexes have been linked with increased prevalence of certain aspects of the metabolic syndrome (22,(53)(54)67). We hypothesize that ER␣ is important in the regulation of tissue substrate metabolism and inflammatory signaling and thus is critical in modulating insulin action and adiposity.It is now widely accepted that impaired fatty acid metabolism and/or fatty acid oversupply cause heightened inflammatory signaling, and these are central contributors to whole body insulin resistance (3,41,84). Accumulation of lipid intermediates in insulin-responsive tissues can activate a host of "stress" kinases,...