Cystathionine γ-lyase: Clinical, metabolic, genetic, and structural studies

We report studies of six individuals with marked elevations of cystathionine in plasma and/or urine. Studies of CTH, the gene that encodes cystathionine γ-lyase, revealed the presence among these individuals of either homozygous or compound heterozygous forms of a novel large deletion, p.Gly57_Gln196del, two novel missense mutations, c.589C>T (p.Arg197Cys) and c.932C>T (p.Thr311Ile), and one previously reported alteration, c.200C>T (p.Thr67Ile). Another novel missense mutation, c.185G>T (p.Arg62His), was found in heterozygous form in three mildly hypercystathioninemic members of a Taiwanese family. In one severely hypercystathioninemic individual no CTH mutation was found. Brief clinical histories of the cystathioninemic/cystathioninuric patients are presented. Most of the novel mutations were expressed and the CTH activities of the mutant proteins determined. The crystal structure of the human enzyme, hCTH, and the evidence available as to the effects of the mutations in question, as well as those of the previously reported p.Gln240Glu, on protein structure, enzymatic activity, and responsiveness to vitamin B₆ administration are discussed. Among healthy Czech controls, 9.3% were homozygous for CTH c.1208G>T (p.Ser403Ile), previously found homozygously in 7.5% of Canadians for whom plasma total homocysteine (tHcy) had been measured. Compared to wild-type homozygotes, among the 55 Czech c.1208G>T (p.Ser403Ile) homozygotes a greater level of plasma cystathionine was found only after methionine loading. Three of the four individuals homozygous or compound heterozygous for inactivating CTH mutations had mild plasma tHcy elevations, perhaps indicating a cause-and-effect relationship. The experience with the present patients provides no evidence that severe loss of CTH activity is accompanied by adverse clinical effects.     

MTHFR和CBS基因多态性与低出生体重的关系研究

目的探讨母亲亚甲基四氢叶酸还原酶（MTHFR）基因C677T、胱硫醚β-合酶（CBS）基因T833C与子代低出生体重发生之间的关系。方法运用聚合酶链反应（PCR）-限制性片段长度多态性与PCR-扩增阻滞突变体系技术分别检测母亲的MTHFR、CBS基因型,对MTHFR基因型、CBS基因型、基因型的交互作用与低出生体重的关系进行分析。结果MTHFR基因突变型、CBS基因突变型对低出生体重影响无统计学意义（P〉0．05）,但MTHFR基因突变型与CBS基因突变型对低出生体重的影响存在交互作用（OR=3．155,95％CI：1．229—8．528）。结论母亲MTHFR基因C677T、CBS基因T833C,与子代低出生体重发生无关,但MTHFR基因突变型与CBS基因突变型存在交互作用,其能增加子代低出生体重发生的危险。     

同型半胱氨酸及胱硫醚β-合酶基因多态性与广西百色地区 妊娠期高血压疾病的相关性研究

目的:初步探讨同型半胱氨酸(Hcy)及其代谢酶-胱硫醚β-合酶(CBS)基因G919A多态性与广西百色地区妊娠期高血压疾病(HDP)形成的相关性。方法:等位基因特异性扩增法及酶联免疫分析法(ELISA)检测61例HDP患者(病例组)及50例正常人(对照组)CBS G919A基因型及血浆Hcy水平。结果:CBS G919A出现G/G、G/A两种基因型,病例组G/G、G/A型频率及A等位基因频率分别为32.79%、67.21%及33.61%,对照组分别为36.00%、64.00%及32.00%,两组基因型频率及A等位基因频率均无统计学差异(P>0.05);病例组血浆Hcy水平(11.36±3.45)μmol/L,较对照组(7.92±2.26)μmol/L明显升高(P<0.01),两组间各基因型Hcy水平比较,差异均有统计学意义(P<0.01),但两组内各基因型Hcy均无统计学差异(P>0.05)。结论:CBS G919A基因多态性与广西百色地区HDP发病无明显相关性,该位点基因突变可能并不足以构成该地区HDP发病的独立遗传风险因素,但高同型半胱氨酸血症(HHcy)与该地区HDP发病有一定关系。     

Birth prevalence of homocystinuria

Serious complications of homocystinuria caused by cystathionine beta-synthase deficiency can be prevented by early intervention. We determined the prevalence of 6 specific mutations in 1133 newborn blood samples. Our results suggest that homocystinuria is more common than previously reported. Newborn screening for homocystinuria through mutation detection should be further considered.     

敏感硫电极法在测定心血管组织细胞及血浆胱硫醚-γ-裂解酶/硫化氢的应用

目的:建立测定微量硫化氢(Hydrogen sulfide, H2S)的敏感硫电极法.方法:根据硫化氢的理化特性,应用化学反应将溶液中物理溶解和化学形式存在的硫化氢转变成硫离子(S2-),应用敏感硫电极检测微量S2-,换算出溶液中H2S,构建了敏感硫电极检测H2S的方法.并检测了大鼠及人血浆中H2S的浓度、大鼠心血管组织中内源性H2S的含量以及大鼠心血管组织和细胞胱硫醚-γ-裂解酶(cystathionine-γ-lyase, CSE)的活性.结果:敏感硫电极检测1～80 μmol/L的S2-有较好的指数相关关系,应用该方法检测到雄性和雌性大鼠血浆H2S的浓度分别为(40±4)和(41±5) μmol/L,差异无统计学意义,人类男性和女性静脉血血浆H2S浓度分别为(33±4) μmol/L 和(35±5) μmol/L,差异无统计学意义.雌、雄大鼠主动脉组织H2S的含量分别为每毫克蛋白(24±6)和(25±5) nmol,心肌组织含量分别为每毫克蛋白(19±4) 和(19±6) nmol,差异无统计学意义.采用敏感硫电极法测量主动脉组织CSE活性与传统方法测量结果差异无统计学意义,但可精确测量出血管平滑肌细胞CSE的活性.结论:敏感硫电极法可以应用于CSE/H2S信号通路的检测.     

Gaseous transmitters in human retinogenesis

Endogenous gaseous transmitters (nitric oxide, carbon monoxide, and hydrogen sulphide) form a special neuromodulation system mediating the development and modification of nerve centers. Here, we examined the localization of key gaseous transmitter enzymes: cystathionine β-synthetase (CBS), cystathionine γ-lyase (CSE), heme oxygenase 2 (HO-2), and constitutive NO synthase (nNOS) in the fetal human retina at different stages of development. The number of CBS- and CSE-positive photoreceptors and intermediate retinal neurons was high in trimester I and gradually decreased to the end of trimester III. The number of HO-2-positive cells followed the same trend. The number of nNOS-positive intermediate retinal neurons and neurons within the ganglion cell layer showed the opposite dynamics with the peak in trimester III. The results are interpreted in terms of the role of gaseous transmitters in retinogenesis and cytoprotection.     

外源性H2S对血管性痴呆模型大鼠海马组织H2S浓度和胱硫醚β-合酶表达的影响

目的 探讨外源性硫化氢(hydrogen sulfide,H2 S)对血管性痴呆(vascular dementia,VaD)大鼠海马组织H2 S浓度和胱硫醚 β-合酶(cystathionineβ-synthase,CBS)表达的影响.方法 采用改良四血管法制作大鼠VaD模型,应用随机数字表法分为假手术组、模型组、小剂量和大剂量NaHS组,再按照模型制作后时间进一步分为1 d、7 d和30 d亚组.小剂量和大剂量NaHS组分别模型制作后每日腹腔注射NaHS 30μmol/kg和100μmol/kg,假手术组和VaD模型组每日腹腔注射等体积生理盐水.应用Morris水迷宫实验评价大鼠学习记忆能力,应用实时免疫荧光聚合酶链反应检测海马组织CBS mRNA表达,应用蛋白质印迹法检测海马组织CBS蛋白表达.结果 Morris水迷宫实验显示,模型组、小剂量和大剂量NaHS组逃避潜伏期均较假手术组显著延长(P均<0.05),穿越平台次数均较模型组显著减少(P均<0.05),小剂量和大剂量NaHS组逃避潜伏期均较模型组显著缩短(P均<0.05).模型组、小剂量和大剂量NaHS组海马H2 S含量均较假手术组显著降低,但小剂量和大剂量NaHS组显著高于模型组(P均<0.05).模型组、小剂量和大剂量NaHS组海马CBS mRNA和蛋白表达均显著低于假手术组(P均<0.05),且小剂量和大剂量NaHS组与模型组无显著差异.结论 外源性H2 S能改善VaD大鼠学习记忆能力,可能与增高海马组织H2 S含量有关,但对CBS表达无影响.     

Targeting hydrogen sulfide as a promising therapeutic strategy for atherosclerosis

Physiological concentrations of nitric oxide (NO) and carbon monoxide (CO) have multiple protective effects in the cardiovascular system. Recent studies have implicated hydrogen sulfide (H₂S) as a new member of vasculoprotective gasotransmitter family, behaving similarly to NO and CO. H₂S has been demonstrated to inhibit multiple key aspects of atherosclerosis, including atherogenic modification of LDL, monocytes adhesion to the endothelial cells, macrophage-derived foam cell formation and inflammation, smooth muscle cell proliferation, neointimal hyperplasia, vascular calcification, and thrombogenesis. H₂S also decreases plasma homocysteine levels in experimental animal models. In the human body, H₂S production is predominantly catalyzed by cystathionine-β-synthase (CBS) and cystathionine γ-lyase (CSE). CSE is the primary H₂S-producing enzyme in the vasculature. Growing evidence suggests that atherosclerosis is associated with vascular CSE/H₂S deficiency and that H₂S supplementation by exogenous H₂S donors (such as NaHS and GYY4137) attenuates, and H₂S synthesis suppression by inhibitors (such as D, L-propargylglycine) aggravates the development of atherosclerotic plaques. However, it remains elusive whether CSE deficiency plays a causative role in atherosclerosis. A recent study (Circulation. 2013; 127: 2523–2534) demonstrates that decreased endogenous H₂S production by CSE genetic deletion accelerates atherosclerosis in athero-prone ApoE^−/− mice, pinpointing that endogenously produced H₂S by CSE activation may be of benefit in the prevention and treatment of atherosclerosis. This study will facilitate the development of H₂S-based pharmaceuticals with therapeutic applications in atherosclerosis-related cardiovascular diseases.     

同型半胱氨酸和胱硫醚-β合成酶基因多态性与颅内动脉瘤的关系

目的 探讨同型半胱氨酸和胱硫醚-β合成酶基因(CBS)844ins 68基因多态性与颅内动脉瘤的关系.方法 运用多聚酶链反应技术和荧光偏振法(FPIA)检测76例颅内动脉瘤及143例正常人CBS 844ins 68基因多态性和血浆总Hcy水平.结果 ①AD组CBS844ins 68 D/D、D/I、I/I基因型频率(%...