Differential expression patterns of mRNAs for P2X receptor subunits in neurochemically characterized dorsal root ganglion neurons in the rat.
The ionotropic purine receptors, P2X receptors, are composed of an assembly of multiple P2X subunits. At present, seven subunits have been cloned and named "P2X1-7." We examined the precise distribution of mRNAs for these subunits in the rat lumbar dorsal root ganglion (DRG) by in situ hybridization histochemistry (ISHH) using riboprobes and characterized their expression among some neuronal subpopulations by ISHH and immunohistochemistry. P2X1 was not expressed by DRG neurons. P2X2 mRNA was preferentially expressed by neurofilament (NF)-200 negative small-sized neurons expressing Ret, but not TrkA or TrkC mRNAs. P2X3 mRNA was mainly expressed by NF-200-negative neurons. Most P2X3-positive neurons had Ret mRNA, and about a half of them coexpressed TrkA and TRPV1 mRNAs. P2X4 was the most ubiquitous subunit, evenly distributing among all examined neuronal subpopulations. P2X5 and P2X6 were expressed by about half of the neurons, and most of these neurons were NF-200-positive. P2X7 mRNA-expressing neurons were quite rare. We further examined the coexpression of all pairs of P2X2-P2X6 mRNAs in DRG neurons and found that: 1) P2X4 was always present in combination with the other subunits. 2) All TrkC neurons had three subunits, P2X4, P2X5, and P2X6, and made up 32% of the total neurons. 3) 12.5% of the total neurons had both P2X2 and P2X3. 4) 12.9% of the neurons had both P2X3 and P2X5. We determined the neuronal subpopulation-specific distribution of P2X subunits in the DRG. These findings suggest possible combinations of subunits of native P2X receptor in DRG neurons.
Kobayashi
Kimiko
K
Department of Anatomy and Neuroscience, Hyogo College of Medicine, Hyogo 663-8501, Japan.
Fukuoka
Tetsuo
T
Yamanaka
Hiroki
H
Dai
Yi
Y
Obata
Koichi
K
Tokunaga
Atsushi
A
Noguchi
Koichi
K
D000818:Animals; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D020869:Gene Expression Profiling; D017403:In Situ Hybridization; D007473:Ion Channels / Q000378:metabolism; D008159:Lumbar Vertebrae; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000378:metabolism; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D021122:Protein Subunits / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051096:Proto-Oncogene Proteins c-ret; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D050916:TRPV Cation Channels; D014018:Tissue Distribution
D007473:Ion Channels; D021122:Protein Subunits; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C495001:Ret protein, rat