title: Expression of nuclear receptor coactivators in androgen-responsive and -unresponsive motoneurons.
abstract: Adult rat lumbar motoneurons in the spinal nucleus of the bulbocavernosus (SNB) respond to androgens with an increase in soma size. This response is mediated by the androgen receptor (AR) in these motoneurons. Interestingly, other lumbar motoneurons in the rat possess the AR, yet do not respond to androgens in this fashion. This paradox suggests the existence and participation of nuclear receptor coregulators in conferring direct androgen-responsiveness to select motoneurons in the adult rat spinal cord. Nuclear receptor coregulators have received much attention recently for their proposed role in enhancing or repressing the transcriptional activity of steroid hormone receptors. The present study used immunocytochemistry to identify a number of nuclear receptor coactivators that are expressed by adult lumbar motoneurons: SRC-1, SRC-2, CBP, p300, and cJUN. Results of this study indicate that all five of these coactivators are abundantly expressed in the androgen-responsive SNB, and in two adjacent motor pools, the androgen-responsive dorsolateral nucleus (DLN), and the androgen-unresponsive retrodorsolateral nucleus (RDLN). While we detected significant regional differences for only SRC-1 and cJUN, the SNB consistently contained the highest percentage of immunoreactive motoneurons for all five cofactors examined. Our results indicate five different putative cofactors have the potential to participate in motoneuronal responses to androgens, since their distribution overlaps well with the distribution of ARs in these motoneurons.
authors.affiliation: Neuroscience Program and Department of Psychology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Erin L
authors.initials: EL
authors.lastname: O'Bryant
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Jordan
mesh_terms: D000818:Animals; D050882:CREB-Binding Protein; D002467:Cell Nucleus / Q000378:metabolism*; D050881:E1A-Associated p300 Protein; D051548:Histone Acetyltransferases; D008159:Lumbar Vertebrae; D008297:Male; D009046:Motor Neurons / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D014018:Tissue Distribution; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C498003:Ncoa2 protein, rat; D009687:Nuclear Proteins; D051958:Nuclear Receptor Coactivator 2; D016755:Proto-Oncogene Proteins c-jun; D011944:Receptors, Androgen; D015534:Trans-Activators; D014157:Transcription Factors; D050882:CREB-Binding Protein; C494365:Crebbp protein, rat; D050881:E1A-Associated p300 Protein; C494362:Ep300 protein, rat; D051548:Histone Acetyltransferases; D056920:Nuclear Receptor Coactivator 1