Human and Murine Pituitary Expression of Leukemia Inhibitory Factor
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Human and murine pituitary expression of leukemia inhibitory factor. Novel intrapituitary regulation of adrenocorticotropin hormone synthesis and secretion. S Akita, … , O Zand, S Melmed J Clin Invest. 1995;95(3):1288-1298. https://doi.org/10.1172/JCI117779. Research Article Leukemia inhibitory factor (LIF) gene expression was detected in human fetal pituitary tissue by expression of LIF mRNA transcripts, protein immunocytochemistry, and immunoelectron microscopy. Fetal LIF immunoreactivity colocalized with 30% of ACTH-expressing cells, approximately 20% of somatotrophs, and approximately 15% of non-hormone-expressing cells. LIF was also strongly expressed in normal adult pituitary and in four growth hormone-producing and two ACTH- producing adenomas, but not in eight nonfunctioning pituitary tumors. Culture of fetal cells expressing surface LIF-binding sites demonstrated predominance of in vitro ACTH secretion as compared with other pituitary hormones. In AtT-20 murine cells, LIF (ED50 10 pM) stimulated basal proopiomelanocortin mRNA levels by 40% and corticotropin-releasing hormone-induced ACTH secretion (two- to threefold), as did oncostatin M (ED50 30 pM), a related peptide. ACTH responses were not further enhanced by both cytokines together, which is consistent with their shared receptor. Anti-LIF antiserum neutralized basal and LIF-induced ACTH secretion, suggesting autocrine regulation of ACTH by LIF. The results show that human pituitary cells express the LIF gene and LIF-binding sites, predominantly in corticotrophs. Pituitary LIF expression and LIF regulation of proopiomelanocortin and ACTH reflect an intrapituitary role for LIF in modulating early embryonic determination of specific human pituitary cells and as a paracrine or autocrine regulator of mature ACTH. Find the latest version: https://jci.me/117779/pdf Human and Murine Pituitary Expression of Leukemia Inhibitory Factor Novel Intrapituitary Regulation of Adrenocorticotropin Hormone Synthesis and Secretion Sadanori Akita, * Jonathan Webster, * Song-Guang Ren, * Hirofumi Takino, * Jonathan Said, * Odelia Zand, * and Shlomo Melmed* *Department of Medicine and tDepartment of Pathology, Cedars-Sinai Medical Center-UCLA School of Medicine, Los Angeles, California 90048 Abstract cific cell types secreting either growth hormone (GH),' prolac- tin (PRL), adrenocorticotropin (ACTH), thyroid-stimulating Leukemia inhibitory factor (LIF) gene expression was de- hormone (TSH), and gonadotropin (follicle-stimulating hor- tected in human fetal pituitary tissue by expression of LIF mone [FSH] and luteinizing hormone [LH]) hormones (1). mRNA transcripts, protein immunocytochemistry, and im- Each of these trophic hormones is under stimulatory or inhibi- munoelectron microscopy. Fetal LIF immunoreactivity colo- tory mediation by unique hypothalamic hormones that bind to calized with 30% of ACTH-expressing cells, - 20% of so- specific pituitary cell surface receptors (2). matotrophs, and - 15% of non-hormone-expressing cells. Specific pituitary cell types are also regulated by intrapitui- LIF was also strongly expressed in normal adult pituitary tary cytokines and growth factors that mediate cell growth or and in four growth hormone-producing and two ACTH- local regulation of angiogenesis. The pituitary is an abundant producing adenomas, but not in eight nonfunctioning pitu- source of several growth factors, including basic fibroblast itary tumors. Culture of fetal cells expressing surface LIF- growth factor, which modulates PRL and TSH release in vitro binding sites demonstrated predominance of in vitro ACTH (3, 4). Epidermal growth factor modulates pituitary secretion secretion as compared with other pituitary hormones. In in vitro (5-7), and transforming growth factor-a is expressed AtT-20 murine cells, LIF (ED50 10 pM) stimulated basal by pituitary lactotrophs (8). Insulin-like growth factor I is ex- proopiomelanocortin mRNA levels by 40% and corticotro- pressed and regulated in somatotrophs and has been recognized pin-releasing hormone-induced ACTH secretion (two- to as a mediator of GH synthesis (9, 10). Interleukins 1 and 6 threefold), as did oncostatin M (ED50 30 pM), a related have also been detected in rat and human pituitary tissue ( 11), peptide. ACTH responses were not further enhanced by and these cytokines have been shown to regulate the corticotro- both cytokines together, which is consistent with their pin-releasing hormone (CRH) -ACTH axis in vitro (12) and shared receptor. Anti-LIF antiserum neutralized basal and in vivo (13). LIF-induced ACTH secretion, suggesting autocrine regula- Since growth and differentiation of hormone-secreting and tion of ACTH by LIF. The results show that human pitu- non-hormone-secreting pituitary cells may be mediated by par- itary cells express the LIF gene and LIF-binding sites, pre- acrine regulators of angiogenesis and endothelial cell growth dominantly in corticotrophs. Pituitary LIF expression and (14), we investigated whether the physiological development LIF regulation of proopiomelanocortin and ACTH reflect an of the human pituitary is associated with expression of leukemia intrapituitary role for LIF in modulating early embryonic inhibitory factor (LIF). LIF, originally isolated as an inhibitor determination of specific human pituitary cells and as a of mouse Ml myeloid leukemia cells ( 15), stimulates prolifera- paracrine or autocrine regulator of mature ACTH. (J. Clin. tion of hematopoietic progenitor cells, maintains the develop- Invest. 1995. 95:1288-1298.) Key words: pituitary adenoma mental potential of embryonic stem cells by suppressing differ- * Cushing's disease * acromegaly * pituitary cytokine entiation, modulates several differentiated cell functions, and promotes differentiation of cholinergic neurons ( 16). LIF and Introduction oncostatin M (OSM) share 25% amino acid homology (17, 18), activate a common gpl30 receptor subunit (19), and are Mechanisms controlling embryologic development of fetal pitu- produced by a variety of cell types, including bone marrow itary tissue may provide important insights into the differentia- stromal cells, thymic epithelial cells, fibroblasts, and a number tion of pituitary function. Cells of the anterior pituitary express of malignancies (17). highly differentiated trophic hormone gene products, and their LIF has been shown to be secreted by cultured bovine pitu- cytogenesis from a common pituitary stem cell involves com- itary follicular cells and to regulate bovine vascular systems plex nuclear and membrane signaling systems, resulting in spe- (20). We therefore investigated the expression of LIF in human fetal and adult pituitary and tested the action of LIF on pituitary function. The results show that the LIF gene is expressed in the developing human fetal pituitary and in both normal and Address correspondence to Shlomo Melmed, MD, Endocrinology B- 131, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los tumorous adult pituitary tissue. Using AtT-20 murine cortico- Angeles, CA 90048. Phone: 310-855-4691; FAX: 310-967-0119. troph cells, LIF and OSM were also shown to stimulate proopio- Received for publication 15 September 1994 and in revised form 17 October 1994. 1. Abbreviations used in this paper: CRH, corticotropin-releasing hor- J. Clin. Invest. mone; FSH, follicle-stimulating hormone; GH, growth hormone; LH, © The American Society for Clinical Investigation, Inc. luteinizing hormone; LIF, leukemia inhibitory factor; LIF-R, leukemia 0021-9738/95/03/1288/11 $2.00 inhibitory factor receptor; OSM, oncostatin M; POMC, proopiomelano- Volume 95, March 1995, 1288-1298 cortin; PRL, prolactin; TSH, thyroid-stimulating hormone. 1288 S. Akita, J. Webster, S.-G. Ren, H. Takino, J. Said, 0. Zand, and S. Melmed melanocortin (POMC) mRNA and basal and CRH-induced and antibiotics after washing. The remainder of the specimen was used ACTH secretion. These LIF actions as well as endogenous for cell sorting or immunohistochemistry. ACTH secretion are blocked by immunoneutralizing anti-LIF For primary cultures, - 104 cells were seeded in multiwells and antiserum. The results indicate an intrapituitary autocrine or incubations were continued for up to 24 h, after which the medium paracrine mediation of the CRH-ACTH axis by LIF. was collected and stored at -20°C for later hormone measurement by commercial radioimmunoassay (Nichols Institute, Reference Labora- tories, San Juan Capistrano, CA). Cells collected after FACS sorting (see following section) were similarly incubated in vitro. These included Methods cell populations that were positive for both CD surface antigen and biotinylated LIF receptor (LIF-R), as well as a population of LIF-R- Human fetal pituitary tissue. The use of human fetal tissue followed negative cells. guidelines outlined by the National Advisory Board on Ethics in Repro- Immunofluorescence staining and cell sorting. Fresh single-cell sus- duction (21). Tissues were derived from third party referrals for thera- pensions were double stained using both direct and indirect immunoflu- peutic termination to an independent facility with no direct or indirect orescence procedures (24). 106 cells were first incubated with conju- participation of the investigators in the termination decision. Written gated phycoerythrin (PE) or FITC-conjugated mixed murine mAbs to informed consent was subsequently obtained by the facility for anony- CD2, 3, 4, 8, 14, and 19, which are reactive with lymphocytes (T, mous distribution of aseptic tissue specimens. natural killer, and