Tlili Asma, Jacobs Frank, de Koning Leanne, Mohamed Sirine, Bui Linh-Chi, Dairou Julien, Belin Nicole, Ducros Véronique, Dubois Thierry, Paul Jean-Louis, Delabar Jean-Maurice, De Geest Bart, Janel Nathalie
Univ Paris Diderot, Sorbonne Paris Cité, Unit of Functional and Adaptative Biology, EAC-CNRS 4413, 75013 Paris, France.
Biochim Biophys Acta. 2013 Jun;1832(6):718-28. doi: 10.1016/j.bbadis.2013.02.008. Epub 2013 Feb 18.
Hyperhomocysteinemia, characterized by high plasma homocysteine levels, is recognized as an independent risk factor for cardiovascular diseases. The increased synthesis of homocysteine, a product of methionine metabolism involving B vitamins, and its slower intracellular utilization cause increased flux into the blood. Plasma homocysteine level is an important reflection of hepatic methionine metabolism and the rate of processes modified by B vitamins as well as different enzyme activity. Lowering homocysteine might offer therapeutic benefits. However, approximately 50% of hyperhomocysteinemic patients due to cystathionine-beta-synthase deficiency are biochemically responsive to pharmacological doses of B vitamins. Therefore, effective treatments to reduce homocysteine levels are needed, and gene therapy could provide a novel approach. We recently showed that hepatic expression of DYRK1A, a serine/threonine kinase, is negatively correlated with plasma homocysteine levels in cystathionine-beta-synthase deficient mice, a mouse model of hyperhomocysteinemia. Therefore, Dyrk1a is a good candidate for gene therapy to normalize homocysteine levels. We then used an adenoviral construct designed to restrict expression of DYRK1A to hepatocytes, and found decreased plasma homocysteine levels after hepatocyte-specific Dyrk1a gene transfer in hyperhomocysteinemic mice. The elevation of pyridoxal phosphate was consistent with the increase in cystathionine-beta-synthase activity. Commensurate with the decreased plasma homocysteine levels, targeted hepatic expression of DYRK1A resulted in elevated plasma paraoxonase-1 activity and apolipoprotein A-I levels, and rescued the Akt/GSK3 signaling pathways in aorta of mice, which can prevent homocysteine-induced endothelial dysfunction. These results demonstrate that hepatocyte-restricted Dyrk1a gene transfer can offer a useful therapeutic targets for the development of new selective homocysteine lowering therapy.
高同型半胱氨酸血症以血浆同型半胱氨酸水平升高为特征，被认为是心血管疾病的独立危险因素。同型半胱氨酸是甲硫氨酸代谢的产物，其合成涉及B族维生素，细胞内利用较慢，导致其进入血液的通量增加。血浆同型半胱氨酸水平是肝脏甲硫氨酸代谢以及受B族维生素和不同酶活性影响的过程速率的重要反映。降低同型半胱氨酸水平可能具有治疗益处。然而，约50%因胱硫醚-β-合酶缺乏导致高同型半胱氨酸血症的患者对药理剂量的B族维生素有生化反应。因此，需要有效的降低同型半胱氨酸水平的治疗方法，基因治疗可能提供一种新方法。我们最近发现，在高同型半胱氨酸血症小鼠模型（胱硫醚-β-合酶缺乏小鼠）中，丝氨酸/苏氨酸激酶DYRK1A的肝脏表达与血浆同型半胱氨酸水平呈负相关。因此，Dyrk1a是使同型半胱氨酸水平正常化的基因治疗的良好候选者。然后，我们使用一种腺病毒构建体，将DYRK1A的表达限制在肝细胞中，发现在高同型半胱氨酸血症小鼠中进行肝细胞特异性Dyrk1a基因转移后，血浆同型半胱氨酸水平降低。磷酸吡哆醛的升高与胱硫醚-β-合酶活性的增加一致。与血浆同型半胱氨酸水平降低相一致，DYRK1A的靶向肝脏表达导致血浆对氧磷酶-1活性和载脂蛋白A-I水平升高，并挽救了小鼠主动脉中的Akt/GSK3信号通路，这可以预防同型半胱氨酸诱导的内皮功能障碍。这些结果表明，肝细胞限制性Dyrk1a基因转移可为开发新的选择性降低同型半胱氨酸治疗方法提供有用的治疗靶点。
