Alhawaj Raed, Patel Dhara, Kelly Melissa R, Sun Dong, Wolin Michael S
Department of Physiology, New York Medical College, Valhalla, New York.
Department of Physiology, New York Medical College, Valhalla, New York
Am J Physiol Lung Cell Mol Physiol. 2015 Apr 1;308(7):L719-28. doi: 10.1152/ajplung.00155.2014. Epub 2015 Feb 6.
This study examines how heme biosynthesis modulation with δ-aminolevulinic acid (ALA) potentially functions to prevent 21-day hypoxia (10% oxygen)-induced pulmonary hypertension in mice and the effects of 24-h organoid culture with bovine pulmonary arteries (BPA) with the hypoxia and pulmonary hypertension mediator endothelin-1 (ET-1), with a focus on changes in superoxide and regulation of micro-RNA 204 (miR204) expression by src kinase phosphorylation of signal transducer and activator of transcription-3 (STAT3). The treatment of mice with ALA attenuated pulmonary hypertension (assessed through echo Doppler flow of the pulmonary valve, and direct measurements of right ventricular systolic pressure and right ventricular hypertrophy), increases in pulmonary arterial superoxide (detected by lucigenin), and decreases in lung miR204 and mitochondrial superoxide dismutase (SOD2) expression. ALA treatment of BPA attenuated ET-1-induced increases in mitochondrial superoxide (detected by MitoSox), STAT3 phosphorylation, and decreases in miR204 and SOD2 expression. Because ALA increases BPA protoporphyrin IX (a stimulator of guanylate cyclase) and cGMP-mediated protein kinase G (PKG) activity, the effects of the PKG activator 8-bromo-cGMP were examined and found to also attenuate the ET-1-induced increase in superoxide. ET-1 increased superoxide production and the detection of protoporphyrin IX fluorescence, suggesting oxidant conditions might impair heme biosynthesis by ferrochelatase. However, chronic hypoxia actually increased ferrochelatase activity in mouse pulmonary arteries. Thus, a reversal of factors increasing mitochondrial superoxide and oxidant effects that potentially influence remodeling signaling related to miR204 expression and perhaps iron availability needed for the biosynthesis of heme by the ferrochelatase reaction could be factors in the beneficial actions of ALA in pulmonary hypertension.
本研究探讨了用δ-氨基乙酰丙酸（ALA）调节血红素生物合成如何潜在地预防小鼠21天缺氧（10%氧气）诱导的肺动脉高压，以及用牛肺动脉（BPA）进行24小时类器官培养，同时加入缺氧和肺动脉高压介质内皮素-1（ET-1）的影响，重点关注超氧化物的变化以及信号转导和转录激活因子3（STAT3）的src激酶磷酸化对微小RNA 204（miR204）表达的调节。用ALA治疗小鼠可减轻肺动脉高压（通过肺动脉瓣的超声多普勒血流以及右心室收缩压和右心室肥大的直接测量来评估）、肺动脉超氧化物增加（通过光泽精检测）以及肺miR204和线粒体超氧化物歧化酶（SOD2）表达降低。用ALA处理BPA可减轻ET-1诱导的线粒体超氧化物增加（通过MitoSox检测）、STAT3磷酸化以及miR204和SOD2表达降低。由于ALA增加BPA原卟啉IX（鸟苷酸环化酶的刺激物）和cGMP介导的蛋白激酶G（PKG）活性，因此研究了PKG激活剂8-溴-cGMP的作用，发现其也可减轻ET-1诱导的超氧化物增加。ET-1增加了超氧化物的产生和原卟啉IX荧光的检测，表明氧化条件可能通过亚铁螯合酶损害血红素生物合成。然而，慢性缺氧实际上增加了小鼠肺动脉中亚铁螯合酶的活性。因此，逆转增加线粒体超氧化物和氧化作用的因素，这些因素可能影响与miR204表达相关的重塑信号，也许还影响亚铁螯合酶反应合成血红素所需的铁可用性，可能是ALA在肺动脉高压中发挥有益作用的因素。
