Rationale: Hypertension is the most important risk factor for cardiovascular and cerebrovascular diseases. Getting deep insight into the pathogenesis of hypertension is necessary. Objective: To investigate the role of ANKRD36 in hypertension. Methods and Results: We firstly recruited an essential hypertension cohort, and then performed genome-wide transcriptome analysis with peripheral blood mRNA. ANKRD36 (ankyrin repeat domain 36) was found to be significantly lower expressed in hypertension. The anchorin repeat domain mediates a variety of protein-protein interactions. The ENaC genes expression was found up-regulated in HUVECs with ANKRD36 knockdown by using Affymetrix expression profile chip. In HKC and HEK293T cells, ANKRD36 overexpression significantly down-regulated ENaC genes expression, and ANKRD36 knockdown up-regulated their expression. The ChIP assay and YY1 knockdown showed the expression of ENaC was regulated by ANKRD36 via YY1, a dual function transcription factor ubiquitously expressed in human tissues. CO-IP and fluorescence resonance energy transfer assay confirmed the interaction between ANKRD36 and YY1. The nucleo-cytoplasmic ratio of YY1 decreased when ANKRD36 was overexpressed, and also increased when ANKRD36 was knocked down. ANK2 domain of ANKRD36 was critical to its interacting with YY1. Ankrd36 knockout mice showed higher blood pressure levels and Na+ reabsorption, especially when fed with high-salt diet. Higher ENaC genes expression was observed in renal tubular epithelial cells from the knockout mice, and Yy1 knockdown mitigated the alteration. Ankrd36 knockout mice also showed more sensitive response to ENaC inhibitor amiloride treatment. Conclusions: We identified that ANKRD36 was involved in blood pressure regulation by interacting with YY1 and then altering ENaC genes expression. Lower expressed ANKRD36 in hypertension might be a potential therapeutic target, and the application of ENaC inhibitors on hypertension treatment might be extended when serum K+ levels are closely monitored.

Abnormal thyroid hormone (TH) function has been observed in all components of metabolic syndrome (MetS), but the mechanisms remain unclear. Altered genomic methylation status is closely related to MetS. Our aim was to determine whether methylation regulation in TH function–related genes is involved in MetS. In a small strictly selected cohort, low TH function was observed in MetS group, as well as lower THRB promoter methylation levels in peripheral blood leukocytes in a genome-wide methylation screening by Illumina 450K beadchip. The results of beadchip assay were then confirmed by Sequenom MassARRAY. Low THRB promoter methylation levels and low TH function in MetS were confirmed in another big-size validation cohort. Lower methylation levels were associated with higher THRB expression in peripheral blood leukocytes, and altered THRB promoter methylation status influenced its promoter activity and expression. In the MetS rat models constructed by high fat and high fructose diet, lower TH function was also observed, as well as lower Thrb promoter methylation levels. Furthermore, systematic inflammation observed in MetS was found to induce decreased THRB promoter methylation levels as well as corresponding THRB expression. Additionally, oral treatment with a physiological T3 dose mitigated hypertension and insulin resistance and partially alleviated hepatic steatosis and adipocyte hypertrophy in MetS rats. Low methylation levels of THRB promoter in peripheral blood leukocytes induced by systematic inflammation were involved in low TH function in MetS, whereas low TH function deteriorates MetS. This might serve as a novel therapeutic target of MetS.

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