Pomozi Viola, Brampton Christopher, Szeri Flóra, Dedinszki Dóra, Kozák Eszter, van de Wetering Koen, Hopkins Hi'ilani, Martin Ludovic, Váradi András, Le Saux Olivier
Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary.
Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
J Invest Dermatol. 2017 Mar;137(3):595-602. doi: 10.1016/j.jid.2016.10.035. Epub 2016 Nov 5.
Soft-tissue calcification is associated with aging, common conditions such as diabetes or hypercholesterolemia, and with certain genetic disorders. ABCC6 is an efflux transporter primarily expressed in liver facilitating the release of adenosine triphosphate from hepatocytes. Within the liver vasculature, adenosine triphosphate is converted into pyrophosphate, a major inhibitor of ectopic calcification. ABCC6 mutations thus lead to reduced plasma pyrophosphate levels, resulting in the calcification disorder pseudoxanthoma elasticum and some cases of generalized arterial calcification of infancy. Most mutations in ABCC6 are missense, and many preserve transport activity but are retained intracellularly. We have previously shown that the chemical chaperone 4-phenylbutyrate (4-PBA) promotes the maturation of ABCC6 mutants to the plasma membrane. In a humanized mouse model of pseudoxanthoma elasticum, we investigated whether 4-PBA treatments could rescue the calcification inhibition potential of selected ABCC6 mutants. We used the dystrophic cardiac calcification phenotype of Abcc6 mice as an indicator of ABCC6 function to quantify the effect of 4-PBA on human ABCC6 mutants transiently expressed in the liver. We showed that 4-PBA administrations restored the physiological function of ABCC6 mutants, resulting in enhanced calcification inhibition. This study identifies 4-PBA treatment as a promising strategy for allele-specific therapy of ABCC6-associated calcification disorders.
软组织钙化与衰老、糖尿病或高胆固醇血症等常见病症以及某些遗传疾病相关。ABCC6是一种主要在肝脏中表达的外排转运蛋白,有助于三磷酸腺苷从肝细胞中释放。在肝脏脉管系统中,三磷酸腺苷会转化为焦磷酸,焦磷酸是异位钙化的主要抑制剂。因此,ABCC6突变会导致血浆焦磷酸水平降低,从而引发弹力纤维假黄瘤钙化障碍以及一些婴儿期全身性动脉钙化病例。ABCC6的大多数突变都是错义突变,许多突变保留了转运活性,但却滞留在细胞内。我们之前已经表明,化学伴侣4-苯丁酸(4-PBA)可促进ABCC6突变体成熟至质膜。在弹力纤维假黄瘤的人源化小鼠模型中,我们研究了4-PBA处理是否能够挽救选定的ABCC6突变体的钙化抑制潜能。我们将Abcc6小鼠的营养不良性心脏钙化表型作为ABCC6功能的指标,以量化4-PBA对在肝脏中瞬时表达的人ABCC6突变体的影响。我们发现,给予4-PBA可恢复ABCC6突变体的生理功能,从而增强钙化抑制作用。这项研究确定4-PBA治疗是ABCC6相关钙化障碍等位基因特异性治疗的一种有前景的策略。