The spatial and temporal expression of delta-like protein 1 in the rat pituitary gland during development

Abstract

An analysis of secreted proteins by the signal sequence trap method using a cDNA library of the rat pituitary anlage at embryonic days (E) 13.5 revealed the abundant expression of delta-like protein 1 (Dlk1) in the pituitary gland. Dlk1, an epidermal growth factor-like repeat protein in preadipocytes, functions in maintaining the preadipose state. Expression of Dlk1 mRNA in the pituitary at E13.5 and in the adult pituitary was confirmed by in situ hybridization. The expression pattern of Dlk1 during pituitary development was also studied by immunohistochemistry. Dlk1 protein first appeared in Rathke's pouch and the infundibulum at E11.5; as development proceeded, expression became restricted to the pars distalis and pars tuberalis (PT). Dlk1 was expressed in most ACTH cells during the embryonic stages, but its expression was limited to only a few ACTH cells in the adult pituitary. It was also expressed in a small population of TSH, GTH, and PRL cells throughout development, whereas it was present in the cytoplasm of most GH cells at all developmental stages. Similarly, Dlk1 was localized in the cytoplasm of PT cells during development. These findings provide new insights into the mechanism of Dlk1 regarding its regulation of pituitary hormone-secreting cells during development.

Pituitary Phenotypes of Mice Lacking the Notch Signalling Ligand Delta‐Like 1 Homologue

“…The nonclassical ligand delta‐like 1 homologue (Dlk1), a paternally‐imprinted gene on mouse chromosome 12 , is expressed throughout the developing Rathke's pouch from embryonic day (E) 10.5 and in the adult anterior pituitary, as well as in bone, β‐cells in pancreatic islets, placenta and adrenal glands . The protein is expressed in the majority of GH cells in the pituitary gland, and a low proportion of all other hormone cell types , as well as the Sox2‐expressing putative stem/progenitor cells, which can form pituispheres in culture . In vitro studies have previously shown that, in somatolactotroph GH3 cells overexpressing Dlk1, GH expression and secretion are down‐regulated .…”

Easy detection of hormone secretion from LβT2 cells by using Gaussia luciferase

“…They were fixed in 10% formalin in phosphate-buffered saline (PBS) for 15 min at room temperature (RT), washed three times with PBS, and treated twice with 0.1% Triton in PBS for 10 min at RT. The cells were incubated for 2 h at RT with rabbit anti-Gluc antibody (1:100), mouse monoclonal antibody against ovine LHβ (1:1000) [16], and guinea pig anti-amidated joining peptide (JP), a marker for ACTH cells (ST-3: 1:2000) [17, 18], in PBS containing 1% bovine serum albumin (BSA). After the incubation with each primary antibody, the cells were washed three times with PBS, and stained with Cy3-labeled affinity-purified donkey anti-rabbit IgG (1:600; Jackson Immunoresearch, PA, USA), Alexa 488-labeled affinity-purified donkey anti-mouse IgG (1:400; Jackson Immunoresearch), and Alexa 488-labeled affinity-purified donkey anti-guinea pig IgG (1:400; Jackson Immunoresearch) for 1 h at RT.…”

Extending the knowledge in histochemistry and cell biology

“…By applying the signal sequence trap method (Tashiro et al 1999) to a cDNA library of embryonic rat pituitary, Nakakura et al (2009) revealed the abundant expression of delta-like protein 1 (Dlk1) in this gland. Dlk1 is an epidermal growth factor-like repeat protein maintaining the preadipose state in preadipocytes (Nueda et al 2007).…”