Regulated Endocrine-Specific Protein-18, an emerging endocrine protein in physiology: A literature review.

Abstract

Regulated endocrine-specific protein-18 (Resp18), a novel 18 kDa protein, was first identified in neuroendocrine tissue. Subsequent studies showed that Resp18 is expressed in the adrenal medulla, brain, pancreas, pituitary, retina, stomach, superior cervical ganglion, testis, and thyroid, and also circulates in the plasma. Resp18 has partial homology with the islet cell antigen 512 (IA-2), aka, protein tyrosine phosphatase, receptor type N (PTPRN), but does not have phosphatase activity. Resp18 may serve as an intracellular signal but its function is unclear. However, Resp18 is regulated by dopamine, glucocorticoids, and insulin. We have recently reported that the targeted disruption of the Resp18 locus in Dahl salt-sensitive rats increases their blood pressure and causes renal injury. The aim of this review is to provide a comprehensive summary of the literature that is currently available, especially the expression and proposed organ-specific function of Resp18.