Id-1 expression defines a subset of vimentin/S-100beta-positive, GFAP-negative astrocytes in the adult rat pineal gland.
Id proteins are dominant negative members of the helix-loop-helix (HLH) transcription factor family which are involved in the differentation of many cell types, including glia. We have recently identified the adult rat pineal gland as a major site of Id-1 and Id-3 expression. In the present study, double fluorescence immunocytochemical analysis was used to examine the co-localization of Id-1 and Id-3 with both neuronal (synaptophysin, betaIII-tubulin) and astrocytic markers (GFAP, vimentin, S-100beta) in the rat pineal. In addition to localizing Id-1 and Id-3 protein to the melatonin-producing pinealocytes, we have also made the novel observation that Id-1, but not Id-3, is highly expressed in a population of vimentin-positive/S-100beta-positive/GFAP-negative astrocytes. Surprisingly, Id-1 was primarily cytoplasmic in these cells, and expression extended throughout the cellular processes. The pineal has been recognized previously as a unique region of the central nervous system in which a vimentin-positive/GFAP-negative glial phenotype is maintained in adult mammals. The exclusion of Id-1 from GFAP-positive cells, and expression in a population of vimentin-positive pineal astrocytes is evidence of a role for Id-1 in the adult stabilization of one form of astrocyte. These results identify the rat pineal gland as a model system for the functional analysis of Id-1.
Kofler
Bettina
B
School of Biosciences, Cardiff University, Cardiff CF10 3US, UK.
Bulleyment
Andrew
A
Humphries
Ann
A
Carter
David A
DA
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002454:Cell Differentiation; D018076:DNA, Complementary / Q000096:biosynthesis; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D007150:Immunohistochemistry; D051798:Inhibitor of Differentiation Protein 1; D008297:Male; D008970:Molecular Weight; D020411:Oligonucleotide Array Sequence Analysis; D010870:Pineal Gland / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins; D009418:S100 Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism*
D018076:DNA, Complementary; D005904:Glial Fibrillary Acidic Protein; C497454:ID1 protein, rat; D051798:Inhibitor of Differentiation Protein 1; D012333:RNA, Messenger; D012097:Repressor Proteins; D009418:S100 Proteins; D014157:Transcription Factors; D014746:Vimentin