Document Detail

Characterization and localization of lipocortin 1-binding sites on rat anterior pituitary cells by fluorescence-activated cell analysis/sorting and electron microscopy.
MedLine Citation:
PMID:  9389519     Owner:  NLM     Status:  MEDLINE    
Lipocortin 1 (LC1) is an important mediator of glucocorticoid action in the anterior pituitary gland, where it appears to act via cell surface binding sites to suppress peptide release. We have exploited a combination of fluorescence-activated cell (FAC) analysis/sorting and electron microscopy to detect, characterize, and localize LC1-binding sites on the surface of dispersed rat anterior pituitary cells, using human recombinant LC1 (hu-r-LC1) as a probe. High affinity (Kd = 14 +/- 3 nM) hu-r-LC1-binding sites were detected on approximately 80% of anterior pituitary cells dispersed with collagenase. The binding characteristics of the ligand resembled those observed in leukocytes, in that it was saturable; concentration, Ca2+, and temperature dependent; and abolished by trypsin. Functional studies demonstrated an excellent correlation between the presence of the cell surface binding protein and the capacity of an anti-LC1 monoclonal antibody to abrogate the inhibitory actions of dexamethasone (10 nM) on the release of ACTH initiated in vitro by CRH-41 (1 nM). Morphological analysis of cells harvested by FAC sorting showed that 1) somatotrophs, corticotrophs, lactotrophs, thyrotrophs, and gonadotrophs were all included in the population expressing LC1 binding sites; and 2) the LC1-binding sites assume a punctate distribution across the cell surface. These data show that anterior pituitary cells express high affinity surface LC1-binding protein(s); they thus provide further evidence for a specific membrane mechanism of action of LC1 in regulating the endocrine function of the anterior pituitary.
H C Christian; A D Taylor; R J Flower; J F Morris; J C Buckingham
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Endocrinology     Volume:  138     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1997-12-29     Completed Date:  1997-12-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  5341-51     Citation Subset:  AIM; IM    
Department of Neuroendocrinology, Imperial College School of Medicine, Charing Cross Hospital, London, United Kingdom.
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MeSH Terms
Adrenocorticotropic Hormone / secretion
Annexin A1 / metabolism*
Binding Sites
Blood Cells / metabolism
Cell Separation
Flow Cytometry
Leukocytes / metabolism
Microscopy, Electron
Pituitary Gland, Anterior / cytology,  metabolism*
Recombinant Proteins / metabolism
Tissue Distribution
Reg. No./Substance:
0/Annexin A1; 0/Recombinant Proteins; 9002-60-2/Adrenocorticotropic Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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