Expression of guanylyl cyclase-B (GC-B/NPR2) receptors in normal human fetal pituitaries and human pituitary adenomas implicates a role for C-type natriuretic peptide

Iain R Thompson; Annisa N Chand; Peter J King; Olaf Ansorge; Niki Karavitaki; Ceri Alexander Jones; Dolkun Rahmutula; David G Gardner; Vladimir Zivkovic; Caroline P Wheeler-Jones; Imelda M McGonnell; Márta Korbonits; Richard A Anderson; John A H Wass; Alan S McNeilly; Robert C Fowkes

doi:10.1530/ERC-12-0129

Expression of guanylyl cyclase-B (GC-B/NPR2) receptors in normal human fetal pituitaries and human pituitary adenomas implicates a role for C-type natriuretic peptide

¹Endocrine Signalling Group, Veterinary Basic Sciences
²Cardiovascular Research Group and
³Developmental Biology Research Group, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
⁴Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
⁵Neuropathology Department, John Radcliffe Hospital, Oxford OX3 9DU, UK
⁶Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, UK
⁷School of Medicine, Institute of Forensic Medicine, University of Belgrade, 11000 Belgrade, Serbia
⁸Department of Medicine, University of California at San Francisco, San Francisco, California 94143-0540, USA
⁹Medical Research Council Human Reproductive Sciences Unit, The Queen's Medical Research Institute, Centre for Reproductive Biology, Edinburgh EH16 4TJ, UK

(Correspondence should be addressed to R C Fowkes; Email: rfowkes{at}rvc.ac.uk)

Abstract

C-type natriuretic peptide (CNP/Nppc) is expressed at high levels in the anterior pituitary of rats and mice and activates guanylyl cyclase B receptors (GC-B/Npr2) to regulate hormone secretion. Mutations in NPR2/Npr2 can cause achondroplasia, GH deficiency, and female infertility, yet the normal expression profile within the anterior pituitary remains to be established in humans. The current study examined the expression profile and transcriptional regulation of NPR2 and GC-B protein in normal human fetal pituitaries, normal adult pituitaries, and human pituitary adenomas using RT-PCR and immunohistochemistry. Transcriptional regulation of human NPR2 promoter constructs was characterized in anterior pituitary cell lines of gonadotroph, somatolactotroph, and corticotroph origin. NPR2 was detected in all human fetal and adult pituitary samples regardless of age or sex, as well as in all adenoma samples examined regardless of tumor origin. GC-B immunoreactivity was variable in normal pituitary, gonadotrophinomas, and somatotrophinomas. Maximal transcriptional regulation of the NPR2 promoter mapped to a region within −214 bp upstream of the start site in all anterior pituitary cell lines examined. Electrophoretic mobility shift assays revealed that this region contains Sp1/Sp3 response elements. These data are the first to show NPR2 expression in normal human fetal and adult pituitaries and adenomatous pituitary tissue and suggest a role for these receptors in both pituitary development and oncogenesis, introducing a new target to manipulate these processes in pituitary adenomas.