Nutritional Regulation of Cysteine Dioxygenase

描述（由申请人提供）：半胱氨酸催化剂依赖于两种独特的酶，它们是唯一已知的哺乳动物巯基双加氧酶-将分子氧加到巯基上以形成亚磺酸的酶。这两种独特的酶是半胱氨酸双加氧酶（CDO），由CDO 1编码，和半胱胺双加氧酶（ADO，2-氨基乙烷双加氧酶），我们最近发现，由人类基因C10 orf 22编码。临床文献和最近对疾病和对照人群中CDO多态性的研究表明，半胱氨酸代谢受损与硫酸盐和牛磺酸和/或CDO功能丧失突变与各种自身免疫性和神经退行性疾病密切相关。CDO是已知的响应于饮食的最高度调节的代谢酶之一，并且CDO活性的这种稳健调节表明半胱氨酸稳态对生物体非常重要。我们的长期目标是整合分子和生物学研究：（a）进一步阐明CDO和ADO的结构-功能关系，为巯基化学和这些酶的调节提供见解;（B）进一步阐明CDO和ADO在健康个体的中间代谢和生理功能调节中的作用，以及CDO缺乏对自身免疫和/或免疫性疾病的可能作用和贡献。或神经退行性疾病。我们的具体目标是：（1）通过对野生型和突变型酶与底物、产物和底物类似物的复合物的结构和光谱研究，确定CDO的催化机理;（2）结晶和解析野生型ADO的结构，并对其催化机理进行研究;（3）表征CDO敲除或CDO缺陷小鼠的表型，包括具有组织特异性CDO基因破坏的那些小鼠;（4）确定CDO基因破坏的不利影响是否受到饮食操作的影响（例如，通过限制的半胱氨酸、补充的牛磺酸或补充的硫酸盐减少，或通过含有过量含硫氨基酸、低牛磺酸或低硫酸盐的饮食放大）;（5）评估在特定细胞类型或组织中表达的CDO对半胱氨酸代谢和半胱氨酸水平调节的功能贡献;（6）确定可能导致自身免疫性和/或神经变性疾病的发展或进展或严重性的特定机制--包括降低的牛磺酸介导的抗氧化作用、降低的补体调节蛋白G1的表达、降低的糖胺聚糖硫酸化能力和增加的H2S产生--在CDO敲除小鼠模型中改变;和（7）通过产生和研究ADO敲除小鼠模型来评估ADO在半胱胺代谢和亚牛磺酸/牛磺酸生物合成中的作用。 公共卫生相关性：半胱氨酸稳态对生物体非常重要，半胱氨酸双加氧酶是参与调节体内半胱氨酸水平的主要酶，其活性可响应于饮食蛋白质含量的变化而发生约300倍的变化，这些变化在饮食变化的数小时内完成。临床文献和疾病和对照人群中编码半胱氨酸双加氧酶（CDO 1）的基因多态性研究表明，半胱氨酸代谢受损，硫酸盐和牛磺酸和/或CDO 1功能丧失突变与各种自身免疫性和神经退行性疾病密切相关。进一步探索半胱氨酸双加氧酶的结构和功能，并使用小鼠敲除模型来研究对CDO 1的功能丧失突变的影响及其通过饮食的修饰，将进一步提高我们预测和早期诊断相关疾病状态以及通过饮食修饰预防疾病或减轻疾病预防的能力。

DESCRIPTION (provided by applicant): Cysteine catabolism is dependent upon two unique enzymes that are the only known mammalian thiol dioxygenases-enzymes adding molecular oxygen to a sulfhydryl group to form a sulfinic acid. These two unique enzymes are cysteine dioxygenase (CDO), encoded by CDO1, and cysteamine dioxygenase (ADO, 2-aminoethanethiol dioxygenase), which we recently showed to be encoded by human gene C10orf22. The clinical literature and, more recently, the study of CDO polymorphisms in disease and control populations, have shown a strong association of impaired metabolism of cysteine to sulfate and taurine and/or CDO loss-of-function mutations with a variety of autoimmune and neurodegenerative diseases. CDO is one of the most highly regulated metabolic enzymes responding to diet that is known, and this robust regulation of CDO activity suggests that cysteine homeostasis is very important to the living organism. Our long-term goals are integrate molecular and organismal studies (a) to further elucidate the structure-function relations in CDO and ADO to provide insights into thiol chemistry and regulation of these enzymes and (b) to further elucidate the roles of CDO and ADO in intermediary metabolism and regulation of physiological function in healthy individuals as well as the possible roles and contributions of CDO deficiency to autoimmune and/or neurodegenerative diseases. Our specific aims related are (1) to define the catalytic mechanism of CDO through structural and spectroscopic studies of complexes of wild type and mutant enzymes in complex with substrates, products and substrate analogs; (2) to crystallize and solve the structure of wild type ADO, and carry out studies to characterize its catalytic mechanism; (3) to characterize the phenotype of CDO-knockout or CDO-deficient mice, including those with tissue- specific CDO gene disruption; (4) to determine whether adverse effects of CDO gene disruption are affected by dietary manipulations (e.g., reduced by restricted cysteine, supplemental taurine, or supplemental sulfate, or amplified by diets containing excess sulfur amino acids, low taurine, or low sulfate); (5) to assess the functional contribution of CDO expressed in specific cell types or tissues to cysteine metabolism and regulation of cysteine levels; (6) to determine whether specific mechanisms that might contribute to the development or progression or severity of autoimmune and/or neurodegenerative disease -- including reduced taurine mediated antioxidation, reduced expression of the complement regulatory protein DAF, reduced capacity for sulfation of glycosaminoglycans, and increased production of H2S -- are altered in the CDO knockout mouse model; and (7) to assess the role of ADO in cysteamine metabolism and in the biosynthesis of hypotaurine/taurine by generating and studying an ADO knockout mouse model. PUBLIC HEALTH RELEVANCE: Cysteine homeostasis is very important to the living organism, and cysteine dioxygenase, the major enzyme involved in regulating body cysteine levels, can undergo ~300-fold changes in activity in response to changes in dietary protein content with these changes being accomplished within hours of the diet change. The clinical literature and the study of polymorphisms of the gene encoding cysteine dioxygenase (CDO1) in disease and control populations have shown a strong association of impaired metabolism of cysteine to sulfate and taurine and/or CDO1 loss-of-function mutations with a variety of autoimmune and neurodegenerative diseases. Further exploration of the structure and function of cysteine dioxygenase and use of a mouse knockout model to study the effects on loss-of-function mutations of CDO1 and their modification by diet will further our ability for prediction and early diagnosis of related disease states and for prevention of disease or alleviation of disease prevention by dietary modifications.