Dynamic Regulation of microRNA Networks in the Brainstem Characterize Hypertension Development

Abstract

This study aims to elucidate the mechanisms by which microRNAs (miRNA) regulate autonomic control networks driving hypertension development. Using a high‐throughput assay for 419 miRNAs in the Spontaneously Hypertensive Rat (SHR) and Wistar‐Kyoto (WKY) control at three stages of hypertension development, significant differences in expression occurred in 9 miRNAs of the nucleus tractus solitarius (NTS) and rostral ventrolateral medulla (RVLM). Alterations were stage‐ and region‐dependent, differing at hypertension onset in NTS vs prehypertension stage in RVLM. 144 gene targets corresponding to catecholaminergic processes and neuromodulation were predicted using miRWALK and RNA22 databases and tested with high‐throughput qPCR. Using correlational relationships between miRNAs and mRNAs, we observed a double‐negative regulatory motif consisting of a miRNA down‐regulating a negative regulator of a pro‐hypertensive signaling pathway like Angiotensin II signaling or leukotriene‐based inflammation. We observe during the development of hypertension cells in NTS and RVLM alter their patterns of miRNA and gene expression related to neural function. These include many genes related to Ang II and inflammatory processes affecting autonomic balance leading to an increase in blood pressure set point. We confirmed expression of key miRNAs in the brainstem using fluorescent in situ hybridization, and we examined the cell‐type specificity of each miRNA using 10 cell pools of neurons and astrocytes taken from the NTS and RVLM using laser capture microdissection. We demonstrated for the first time that the broad concordance of miRNA dynamics and target gene expression compose a regulatory network in the brainstem underlying hypertension.