Endocrine Abstracts

The mammalian natriuretic peptide family consists of three members, Atrial-, B-type, and C-type natriuretic peptides (ANP, BNP, and CNP respectively), and exert their effects on blood pressure, sodium homeostasis, growth and reproduction, via their selective guanylyl cyclase receptors, GC-A or GC-B. Previous attempts to map spatial expression profiling have generated conflicting results, due predominantly to the range of techniques employed, and the relative paucity of tools to examine the natriuretic peptide system at the molecular level. Here, we describe a comprehensive spatial expression screen of the natriuretic peptide system in mouse tissues, using our novel multiplex qRT-PCR system. Total RNA was extracted from adipose, adrenal, brain, heart, kidney, liver, ovary, and testis of 12-week-old C57/B6 mice, prior to multiplex qRT-PCR analyses (for Nppa, Nppb, Nppc, Npr1, Npr2, Npr3, Corin, Furin, Actb, Gapdh, and Rpl19). Spatial expression profiles for Nppa (ANP) and Nppb (BNP) were tightly conserved, with high levels of each transcript detected in cardiac ventricles. Nppc (CNP) expression was more broadly distributed, with the highest expression levels seen in forebrain. Expression of Npr1 and Npr2 was consistently high in all tissues examined, although the abundance of Npr1 expression in forebrain was only half that seen in other tissues. In contrast, Npr3 (clearance receptor), Corin, and Furin (processing enzymes) were ubiquitously expressed. On further examination, sexually dimorphic differences were seen for Nppc (adrenal and adipose), Npr3 (kidney), Furin (cardiac ventricles), and Corin (liver), suggesting gender-specific roles for these components of the natriuretic peptide system in these tissues. These data represent the most comprehensive tissue-specific expression profiling of the natriuretic peptide system in mice, suggest potential gender-specific roles for CNP signalling in adrenal and adipose tissue, and confirm that the CNP/GC-B is the predominate natriuretic peptide system in the brain.