Identification of a melanocortin receptor expressed by Murine brain microvascular endothelial cells in culture

E. De Angelis, U. G. Sahm, A. R.H. Ahmed, G. W.J. Olivier, L. J. Notarianni, S. K. Branch, S. H. Moss, C. W. Pouton

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Abstract

Microvascular endothelial cells were isolated from the brains of C57 mice and cultured in selective growth media. The isolation and culture techniques employed in this study minimised the contamination by nonendothelial cells such as astrocytes, pericytes, and smooth muscle cells. Microvascular endothelial cells examined using phase contrast light microscopy grew as small colonies of spindle-shaped cells which merged together to form typical contact-inhibited monolayers. The endothelial origin of these cells was determined using several established characterisation techniques. Preliminary receptor binding studies at 4° using [125I-Tyr2, Nle4, D-Phe7]α-melanocyte-stimulating hormone ([125I-Tyr2, Nle4, D-Phe7]α-MSH) suggested the possibility that melanocortin receptors were present on the surface of brain microvascular endothelial cells. Subsequent binding isotherms confirmed that a small population of high-affinity melanocortin receptors was expressed. The existence of a specific binding site for α-MSH was confirmed by photoaffinity labeling with the 4-(1-azi-2,2,2,-trifluoroethyl)benzoic acid (ATB) derivative, [125I-Tyr2, Nle4, D-Phe7, (ATB)-Lys11]α-MSH. SDS-PAGE analysis identified the presence of a specific band with a molecular mass of approximately 45 kDa, which was consistent with previous data on melanoma melanocortin receptors, and represented a ligand-receptor complex. This study suggests that a receptor for α-MSH is expressed on the extracellular surface of murine brain microvascular endothelial cells; however, the physiological role of this receptor is as yet unknown.

Original languageEnglish
Pages (from-to)25-34
Number of pages10
JournalMicrovascular Research
Volume50
Issue number1
DOIs
Publication statusPublished - 1 Jan 1995
Externally publishedYes

Keywords

  • Affinity Labels/metabolism Animals Brain/blood supply/cytology/*metabolism Cell Separation Cells, Cultured Endothelium, Vascular/cytology/metabolism Iodine Radioisotopes Kinetics Mice Molecular Weight Receptors, Corticotropin/chemistry/isolation & purification/*metabolism Receptors, Melanocortin alpha-MSH/analogs & derivatives/metabolism

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