Two microRNAs, miR-330 and miR-125b-5p, mark the juxtaglomerular cell and balance its smooth muscle phenotype.

We have shown that microRNAs (miRNAs) are necessary for renin cell specification and kidney vascular development. Here, we used a screening strategy involving microarray and in silico analyses, along with in situ hybridization and in vitro functional assays to identify miRNAs important for renin cell identity. Microarray studies using vascular smooth muscle cells (SMCs) of the renin lineage and kidney cortex under normal conditions and after reacquisition of the renin phenotype revealed that of 599 miRNAs, 192 were expressed in SMCs and 234 in kidney cortex.

Transcriptional regulator RBP-J regulates the number and plasticity of renin cells.

Renin-expressing cells are crucial in the control of blood pressure and fluid-electrolyte homeostasis. Notch receptors convey cell-cell signals that may regulate the renin cell phenotype. Because the common downstream effector for all Notch receptors is the transcription factor RBP-J, we used a conditional knockout approach to delete RBP-J in cells of the renin lineage.

The microRNA-processing enzyme dicer maintains juxtaglomerular cells.

Juxtaglomerular cells are highly specialized myoepithelioid granulated cells located in the glomerular afferent arterioles. These cells synthesize and release renin, which distinguishes them from other cells. How these cells maintain their identity, restricted localization, and fate is unknown and is fundamental to the control of BP and homeostasis of fluid and electrolytes.