title: Differential expression of the homeobox gene Pitx3 in midbrain dopaminergic neurons.
abstract: The transcription factor Pitx3 is expressed selectively in the midbrain and regulates the differentiation and survival of dopaminergic neurons. Lack of this factor results in a degeneration similar to that seen in Parkinson's disease. We have studied the pattern and the level of expression of Pitx3 in dopaminergic neurons of 3- to 4-week-old Wistar rats. We report Pitx3 expression in almost all dopaminergic substantia nigra (SN) and ventral tegmental area (VTA) neurons. It is coexpressed with the neuroprotective marker calbindin (CB) in a larger population of VTA (43%) than SN (16%) dopaminergic neurons. The level of Pitx3 mRNA, determined by semiquantitative RT-PCR, is approximately 6x higher in VTA than in SN single neurons. In the VTA but not in SN the level of Pitx3 is associated with the presence of CB: in CB-positive neurons the expression of Pitx3 mRNA is 3.6x higher than in CB-negative cells. CB is expressed in a larger population of VTA than SN neurons and the relative level of CB expression is 4x higher in VTA than in SN. A higher Pitx3 expression level and higher coexpression of Pitx3 and CB in VTA than in SN neurons may contribute to the different vulnerability of these dopaminergic nuclei to neurodegeneration.
authors.affiliation: Institute of Neurophysiology, Heinrich-Heine-University, Physiology II, POB 101007, Duesseldorf, Germany. tatiana.korotkova@uni-dusseldorf.de
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Korotkova
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Ponomarenko
authors.forename: Helmut L
authors.initials: HL
authors.lastname: Haas
authors.forename: Olga A
authors.initials: OA
authors.lastname: Sergeeva
mesh_terms: D000465:Algorithms; D000818:Animals; D064026:Calbindins; D004298:Dopamine / Q000502:physiology*; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics*; D007150:Immunohistochemistry; D008297:Male; D008636:Mesencephalon / Q000166:cytology* / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000378:metabolism* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013378:Substantia Nigra / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D017557:Ventral Tegmental Area / Q000166:cytology / Q000378:metabolism
chemical_list: D064026:Calbindins; D018398:Homeodomain Proteins; D064030:S100 Calcium Binding Protein G; D014157:Transcription Factors; C433629:homeobox protein PITX3; D004298:Dopamine