(Pro) renin receptor [(P) RR] is a single trans-membrane receptor that binds to both renin and its precursor prorenin to activate tissue renin-angiotensin system (RAS). In addition, (P) RR induces its own intracellular signaling transduction independent of the RAS. (P) RR also plays a physiological role in the assembly and function of vacuolar H+-ATPase (V-ATPase). It has been reported that (P) RR mRNA is widely expressed in various tissues in human. However, actual sites of (P) RR expression have not been fully elucidated. Therefore, this study was aimed to investigate expression sites of (P) RR in human organs.
Design and Method:
The specimens were derived from autopsy cases to be examined pathologically by (P)RR immunostaining. The reaction was performed by using the (P) RR antiserum (dilution 1:200), which was raised in a rabbit by injecting the peptide fragment of human (P) RR.
(P) RR immunostaining was observed in follicular epithelial cells in thyroid, bronchial epithelial cells in lung, hepatic cells and bile duct epithelial cells in liver, proximal and distal tubules and Henle loop in kidney, zona glomerulosa and zona reticularis in adrenal gland, exocrine glands and ducts in pancreas. (P) RR staining was detected in neurons and glial cells throughout the brain especially in cerebrum, granular layer of hippocampus, Purkinje cell layer and dentate nucleus of cerebellum, anterior lobe of pituitary, medulla oblongata, and hypothalamus. It is noteworthy that apparent immunoreactivity was observed in neurons in paraventricular nucleus and supraoptic nucleus in hypothalamus, important centers for blood pressure (BP) control via regulating water-electrolyte homeostasis and sympathetic nervous system.
The present study showed that (P)RR is expressed in various tissues such as the brain in a cell-specific manner in human. These findings raised the possibility that (P)RR plays numerous physiological roles including central mechanism of BP control.