GCLM C-588T多态与中国人冠状动脉粥样硬化性心脏病遗传易感性的关系

目的 探讨谷氨酸-半胱氨酸连接酶修饰亚单位基因（glutarnat-cysteine ligase modifier subunit gene，GCLM）C-588T多态与中国人冠状动脉粥样硬化性心脏病（coronary heart disease，CHD）遗传易感性的关系。方法 采用聚合酶链反应-限制性片段长度多态方法，检测209例CHD与240名对照的GCLM基因型分布及差异。结果 CHD组及对照组T等位基因频率分别为17．2％及26．3％，T的CHD发病风险是C的0．59倍（95％CI=0．42-0．81。P=0．001）。与C/C纯合子相比，C／T杂合子引起CHD风险为0.67倍（95％CI=0．45～1．01，P=0．056），而T／T纯合子引起CHD风险度显著降低至0.20倍（95％CI=0．06-0．61，P=0．005）。结论 GCLM-588T降低CHD发病风险，提示T/T基因型是中国人CHD的一个遗传保护因素。     

Protection against 2-chloroethyl ethyl sulfide (CEES)-induced cytotoxicity in human keratinocytes by an inducer of the glutathione detoxification pathway

Sulfur mustard (SM or mustard gas) was first used as a chemical warfare agent almost 100 years ago. Due to its toxic effects on the eyes, lungs, and skin, and the relative ease with which it may be synthesized, mustard gas remains a potential chemical threat to the present day. SM exposed skin develops fluid filled bullae resulting from potent cytotoxicity of cells lining the basement membrane of the epidermis. Currently, there are no antidotes for SM exposure; therefore, chemopreventive measures for first responders following an SM attack are needed. Glutathione (GSH) is known to have a protective effect against SM toxicity, and detoxification of SM is believed to occur, in part, via GSH conjugation. Therefore, we screened 6 potential chemopreventive agents for ability to induce GSH synthesis and protect cultured human keratinocytes against the SM analog, 2-chloroethyl ethyl sulfide (CEES). Using NCTC2544 human keratinocytes, we found that both sulforaphane and methyl-2-cyano-3,12-dioxooleana-1,9-dien-28-oate (CDDO-Me) stimulated nuclear localization of Nrf2 and induced expression of the GSH synthesis gene, GCLM. Additionally, we found that treatment with CDDO-Me elevated reduced GSH content of NCTC2544 cells and preserved their viability by ~ 3-fold following exposure to CEES. Our data also suggested that CDDO-Me may act additively with 2,6-dithiopurine (DTP), a nucleophilic scavenging agent, to increase the viability of keratinocytes exposed to CEES. These results suggest that CDDO-Me is a promising chemopreventive agent for SM toxicity in the skin.     

Lipid metabolism and body composition in Gclm(-/-) mice

In humans and experimental animals, high fat diets (HFD) are associated with risk factors for metabolic diseases, such as excessive weight gain and adiposity, insulin resistance and fatty liver. Mice lacking the glutamate–cysteine ligase modifier subunit gene (Gclm(−/−)) and deficient in glutathione (GSH), are resistant to HFD-mediated weight gain. Herein, we evaluated Gclm-associated regulation of energy metabolism, oxidative stress, and glucose and lipid homeostasis. C57BL/6J Gclm(−/−) mice and littermate wild-type (WT) controls received a normal diet or an HFD for 11 weeks. HFD-fed Gclm(−/−) mice did not display a decreased respiratory quotient, suggesting that they are unable to process lipid for metabolism. Although dietary energy consumption and intestinal lipid absorption were unchanged in Gclm(−/−) mice, feeding these mice an HFD did not produce excess body weight nor fat storage. Gclm(−/−) mice displayed higher basal metabolic rates resulting from higher activities of liver mitochondrial NADH-CoQ oxidoreductase, thus elevating respiration. Although Gclm(−/−) mice exhibited strong systemic and hepatic oxidative stress responses, HFD did not promote glucose intolerance or insulin resistance. Furthermore, HFD-fed Gclm(−/−) mice did not develop fatty liver, likely resulting from very low expression levels of genes encoding lipid metabolizing enzymes. We conclude that Gclm is involved in the regulation of basal metabolic rate and the metabolism of dietary lipid. Although Gclm(−/−) mice display a strong oxidative stress response, they are protected from HFD-induced excessive weight gain and adipose deposition, insulin resistance and steatosis.