Externalization of annexin I from a folliculo-stellate-like cell line.

Journal article

Our recent studies on rat pituitary tissue suggest that the annexin I-dependent inhibitory actions of glucocorticoids may not be exerted directly on endocrine cells but indirectly via folliculo-stellate (FS) cells. FS cells contain glucocorticoid receptors and abundant annexin I. We have studied the localization of annexin I in FS cells and the ability of dexamethasone to induce annexin I secretion by an FS (TtT/GF) cell line, using Western blotting and immunofluorescence microscopy. Exposure of TtT/GF cells to dexamethasone (0.1 micro M, 3 h) caused an increase in the amount of annexin I protein in the intracellular compartment and attached to the surface of the cells. In nonpermeabilized cells, immunofluorescence labeling revealed that annexin I immunoreactivity was associated with the cell surface and concentrated in focal patches on the ends of cytoplasmic processes; dexamethasone (0.1 micro M, 3 h) increased both the number and intensity of these foci. Immunogold electron microscopy confirmed in anterior pituitary tissue the presence of immunoreactive-annexin at the surface of FS cell processes contacting endocrine cells. These data support our hypothesis that annexin I is released by FS cells in response to glucocorticoids to mediate glucocorticoid inhibitory actions on pituitary hormone release via a juxtacrine mechanism.

Authors: Chapman, L; Nishimura, A; Buckingham, J; Morris, J; Christian, H

• Publication status: Published
• Journal: Endocrinology
• Volume: 143
• Issue: 11
• Pages: 4330-4338
• Publication date: 2002-11-01
• DOI: 10.1210/en.2002-220529
• EISSN: 1945-7170
• ISSN: 0013-7227
• Language: English
• Keywords: Microscopy, Immunoelectron; Pituitary Gland, Anterior; Animals; Cell Membrane; Dexamethasone; Glucocorticoids; Cell Line; Cell Communication; Blotting, Western; Mice; Pituitary Gland; Annexin A1; Microscopy, Fluorescence; Mice, Inbred C57BL; Fluorescent Antibody Technique