Eriksson Staffan, Wang Liya
Department of Anatomy, Physiology & Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Nucleosides Nucleotides Nucleic Acids. 2008 Jun;27(6):800-8. doi: 10.1080/15257770802146197.
Mitochondrial DNA depletion syndrome (MDS), a reduction of mitochondrial DNA copy number, often affects muscle or liver. Mutations in enzymes of deoxyribonucleotide metabolism give MDS, for example, the mitochondrial thymidine kinase 2 (TK2) and deoxyguanosine kinase (dGK) genes. Sixteen TK2 and 22 dGK alterations are known. Their characteristics and symptoms are described. Levels of five key deoxynucleotide metabolizing enzymes in mouse tissues were measured. TK2 and dGK levels in muscles were 5- to 10-fold lower than other nonproliferating tissues and 100-fold lower compared to spleen. Each type of tissue apparently relies on de novo and salvage synthesis of DNA precursors to varying degrees.
线粒体DNA耗竭综合征（MDS），即线粒体DNA拷贝数减少，常影响肌肉或肝脏。脱氧核苷酸代谢酶的突变会导致MDS，例如线粒体胸苷激酶2（TK2）和脱氧鸟苷激酶（dGK）基因。已知有16种TK2和22种dGK改变。对它们的特征和症状进行了描述。测定了小鼠组织中五种关键脱氧核苷酸代谢酶的水平。肌肉中的TK2和dGK水平比其他非增殖组织低5至10倍，与脾脏相比低100倍。每种组织类型显然在不同程度上依赖于DNA前体的从头合成和补救合成。
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