Renal Dopamine and Angiotensin II Receptor Function in Age-Related Hypertension

描述（由申请方提供）：肾多巴胺D1和血管紧张素II AT1受体通过调节近端肾小管钠转运蛋白维持钠稳态和血压。最近，我们报道，夸大AT 1和减少D1受体功能的老（21个月）Fischer 344 X布朗挪威（FBN）大鼠与氧化应激和高血压的增加，这表明氧化应激在这种现象中的作用。我们的初步研究表明，这些变化与老年大鼠近端小管中AT 1增加和D1受体mRNA减少以及氧化还原敏感性转录因子NF κ B和Sp3的核水平升高有关。在细胞培养中，NFkB表达质粒增加AT 1受体mRNA和蛋白，而Sp3表达质粒减少D1受体mRNA和蛋白。基于这些发现，我们提出测试的中心假设，即“激活转录因子NF κ B和Sp3氧化应激增加AT 1受体功能（NF κ B）和抑制D1受体功能（Sp3），从而有助于老年大鼠的高血压。补充抗氧化剂可减少氧化应激，使NFkB和Sp3活性正常化，恢复AT 1和D1受体功能，并降低老年大鼠的血压。将采取两个具体目标来检验这一假设。目的1将确定氧化应激的病因作用，在夸大肾AT 1和减少D1受体功能，有助于高血压，在清醒的老年大鼠。目的2研究NF κ B和Sp3通过参与表观遗传过程分别激活AT 1和抑制D1受体转录，从而导致氧化应激时AT 1和D1受体功能改变和血压升高的机制。将通过用抗氧化剂降低老年大鼠的氧化应激来研究氧化应激在不利的AT 1和D1受体功能和血压中的致病作用。将通过用各自的shRNA慢病毒颗粒递送至大鼠肾脏耗尽这些蛋白质并通过使用各自的表达载体在细胞培养物中过表达来研究NFkB和Sp3在该现象中的作用。这些研究应该提供一个更好的了解氧化应激导致高血压的机制，随后将导致高血压的靶向治疗。 公共卫生相关性：高血压是老年人高发病率和死亡率的主要原因。在这一人群中，高血压的发病率可能会增加，因为预计在未来几十年中，老年人的数量将急剧增加。我们的研究将确定氧化应激，这是衰老过程的标志，改变了肾脏中存在的两个关键受体功能，并导致老年高血压。所获得的结果将确定未来的治疗目标以及抗氧化剂在健康衰老过程中降低血压的潜在用途。

DESCRIPTION (provided by applicant): Renal dopamine D1 and angiotensin II AT1 receptors by regulating proximal tubular sodium transporters maintain sodium homeostasis and blood pressure. Recently we reported that exaggerated AT1 and reduced D1 receptor function in old (21-month) Fischer 344 X Brown Norway (FBN) rats were associated with increased oxidative stress and high blood pressure suggesting role of oxidative stress in this phenomenon. Our preliminary studies show that these changes are associated with increased AT1 and decreased D1 receptor mRNAs as well as higher nuclear levels of redox-sensitive transcription factors NFkB and Sp3 in proximal tubules of old rats. And, in cell culture NFkB expression plasmid increased AT1 receptor mRNA and protein while Sp3 expression plasmid decreased D1 receptor mRNA and proteins. Based upon these findings we propose to test the central hypothesis that "Activation of transcription factors NFkB and Sp3 upon oxidative stress increases AT1 receptor function (NFkB) and suppresses D1 receptor function (Sp3) thus contributing to high blood pressure in old rats. Antioxidant supplementation reduces oxidative stress, normalizes NFkB and Sp3 activity, restores AT1 and D1 receptor function, and lowers blood pressure in old rats". Two specific aims will be undertaken to test the hypothesis. Aim 1 will identify causative role of oxidative stress in exaggerated renal AT1 and diminished D1 receptor function contributing to high blood pressure as measured in conscious old rats. Aim 2 will study the mechanism that NFkB and Sp3 by engaging epigenetic process activates AT1 while represses D1 receptor transcription, respectively, contributing to altered AT1 and D1 receptor function and increase in blood pressure during oxidative stress. The causative role of oxidative stress in adverse AT1 and D1 receptor function and blood pressure will be studied by reducing oxidative stress in old rats with antioxidant. The role of NFkB and Sp3 in this phenomenon will be studied by depleting these proteins with respective shRNA lentiviral particle delivery to rat kidneys and by their over-expression using respective expression vector in cell cultures. These studies should provide a better understanding of the mechanism by which oxidative stress causes hypertension which would subsequently lead to targeted therapy for hypertension. PUBLIC HEALTH RELEVANCE: High blood pressure is a major contributor to high morbidity and mortality in the elderly. The incidence of high blood pressure in this population group is likely to increase as the number of elderly is predicted to increase dramatically over the next few decades. Our research will identify that oxidative stress, which is a hall-mark of aging process, alters two key receptor function present in the kidney and contributes to high blood pressure in aging. The results obtained will identify future therapeutic targets as well as potential use of antioxidants to reduce blood pressure for a healthy aging process.