S100b-positive cells (follicle satellite cell) drove from two different origins in the rat pituitary

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 112-141-Hypothalamus-Pituitary Development & Biology
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-118
Hideji Yako*1, Masashi Higuchi1, Saishu Yoshida1, Kotaro Horiguchi2, Ken Fujiwara2, Naoko Kanno1, Mo Chen1, Hiroki Ueharu1, Mituyoshi Tsuda1, Takako Kato1, Takashi Yashiro2 and Yukio Kato1
1Meiji University, Kawasaki, Kanagawa, Japan, 2Jichi Medical University School of Medicine
The pituitary is composed of the anterior, intermediate and posterior lobes, in which hormone-producing cells and non-hormone-producing cells are present. Some of the latter cells, follicle satellite cell (FS cell, expressing characteristically S100 protein), are believed to be involved in cell renewal and supply for hormone-producing cells, though vital function of the FS cell is not yet confirmed. Itakura et al. (2007) succeeded in production of the transgenic rats (S100b-GFP rats) that express green fluorescent protein (GFP) specifically in the FS cells. We have an experience that FS cells largely appear in the anterior pituitary at postnatal day and are composing of plural populations using several stem/progenitor markers, indicating heterogeneous origins of the FS cells. To gain further insight into origins of the FS cells, in this study, we re-investigated GFP-positive cells in detail during embryonic development using S100b-GFP rats.

Immunohistochemistry, in addition to a fluorescence observation, was performed for embryonic (E) pituitaries on day E15.5, E18.5, E19.5 and E20.5 using antibodies to SOX2 (stem/progenitor marker and expressing in the pituitary stem/progenitor cell), PRX1 (paired-related homeobox protein; mesenchymal and novel pituitary transcription factor expressing in the pituitary stem/progenitor cell) and GFP. We observed GFP-positive cells at an Atwell's recess of the anterior lobe on E15.5 as invading cells from surrounding area and at a vicinity of the blood vessels on E18.5. In the intermediate lobe, GFP-positive cells were firstly observed on E20.5. Immunohistochemistry for PRX1 showed the PRX1-positive cells were present in the pituitary cells, surrounding mesenchymal cells and invading cells at the Atwell's recess on E15.5 and E18.5. Double staining for SOX2 showed two populations in the GFP/PRX1-double positive cells with the positivity. In the intermediate lobe on E20.5, GFP-positive cells were expressed SOX2 and/or PRX1.

The present study demonstrated that GFP-positive cells, mostly FS cells, were certainly present in the embryonic anterior lobe. In consider the absence of SOX2, some of the GFP-positive cells are mesenchymal origin invading through the Atwell's recess at early period, followed by involving in pituitary vasculogenesis. In conclusion, FS cells are composing of two different origins and already participate in development of the embryonic pituitary.

Nothing to Disclose: HY, MH, SY, KH, KF, NK, MC, HU, MT, TK, TY, YK

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm