Pineal gland expression of the transcription factor Egr-1 is restricted to a population of glia that are distinct from nestin-immunoreactive cells.
Egr-1 is a plasticity-related transcription factor that has been implicated in circadian regulation of the pineal gland. In the present study we have investigated the cellular expression pattern of Egr-1 in the adult rat pineal. Egr-1 protein is restricted to the nucleus of a sub-population of cells. These cells were characterised using a new transgenic rat model (egr-1-d2EGFP) in which green fluorescent protein is driven by the egr-1 promoter. Cellular filling by GFP revealed that Egr-1-positive cells exhibited processes, indicating a glial cell-type morphology. This was confirmed by co-localizing the GFP-filled processes with vimentin and S-100beta. However, GFP/Egr-1 is expressed in only a tiny minority of the previously identified Id-1/vimentin-positive glial cells and therefore represents a novel sub-set of this (GFAP-negative) glial population. We have also demonstrated for the first time an extensive network of nestin-positive cells throughout the adult pineal gland, however these cells do not co-express Egr-1. Our studies have therefore broadened our understanding of the cell populations that constitute the adult pineal. Cellular localization of Egr-1 has revealed that this factor does not appear to be directly involved in pinealocyte production of melatonin but is required in a sub-set of pineal glia.
School of Biosciences, Cardiff University, P.O. Box 911, Museum Avenue, Cardiff, CF10 3US, UK.
Pui-Sin
PS
Man
David A
DA
Carter
D000818:Animals; D051766:Early Growth Response Protein 1 / Q000378:metabolism*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D064231:Nestin; D009457:Neuroglia / Q000166:cytology* / Q000378:metabolism*; D010870:Pineal Gland / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D051766:Early Growth Response Protein 1; D005904:Glial Fibrillary Acidic Protein; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C577486:Nes protein, rat; D064231:Nestin; D049452:Green Fluorescent Proteins