Differential colocalization of Islet-1 and estrogen receptor alpha in the murine preoptic area and hypothalamus during development.
Estrogen receptor (ER) expression and regulation is vital to the correct functioning of the neuroendocrine brain. Islet-1 (Isl-1) is a LIM homeodomain-containing transcription factor that has been implicated in neuronal differentiation, is located in the hypothalamus, and can alter ER function in vitro. We have determined that Isl-1 is localized in several regions of the hypothalamus, including the ER rich areas of the ventromedial nucleus (VMH), the preoptic area, and the anterior hypothalamus. Using double-label immunocytochemistry, we examined the overlap between immunoreactive ERalpha and Isl-1 in these different hypothalamic brain regions. In the developing brain, almost 100% of VMH cells that contain immunoreactive ERalpha also contain Isl-1. However, in older animals, the percentage of double-label cells decreased below 70%. This change is due to a decrease in the number of cells containing Isl-1, because there was no difference in the number of ERalpha-containing cells. By contrast, in more anterior regions of the hypothalamus, cells containing both Isl-1 and ERalpha were less common, with the two populations adjacent to each other, rather than overlapping. These data suggest that, although Isl-1 and ERalpha can interact, they are not always found in the same cells and that regulation of ERalpha function is not under the same control in the VMH, preoptic area, and the anterior hypothalamus.
Davis
Aline M
AM
Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523-1680, USA.
Seney
Marianne L
ML
Walker
Heather J
HJ
Tobet
Stuart A
SA
D000367:Age Factors; D000818:Animals; D047628:Estrogen Receptor alpha; D005260:Female; D018398:Homeodomain Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D060850:LIM-Homeodomain Proteins; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins; D011247:Pregnancy; D011301:Preoptic Area / Q000254:growth & development / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D014157:Transcription Factors; D014697:Ventromedial Hypothalamic Nucleus / Q000254:growth & development / Q000378:metabolism*
D047628:Estrogen Receptor alpha; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D011960:Receptors, Estrogen; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1