Expression and distribution of cholinergic receptors in the human urothelium.
The bladder urothelium not only provides a diffusion barrier but it also serves a sensor function and releases signalling molecules that are considered to act in a paracrine and autocrine fashion, e.g. by acetylcholine. Its actions are conferred by two classes of receptors, i.e. G-protein-coupled muscarinic receptors (MR) and ionotropic nicotinic receptors (nAChR). In this study we set out to determine the expression and distribution of all MR subtypes (M1R-M5R) and nAChR alpha-subunits 7, 9 and 10 in the human urothelium by means of RT-PCR and immunohistochemistry, respectively. Real-time RT-PCR revealed a rank order of MR subtype expression of M2R>>M3R=M5R>M4R=M1R. Immunohistochemistry demonstrated differential distribution patterns with M1R being restricted to basal cells, M2R nearly exclusively found in umbrella cells, whereas M3R and M4R were homogenously distributed and M5R was seen in a decreasing gradient from luminal to basal. As for nAChR alpha-subunits, rank order of expression is alpha7>>alpha10>alpha9, and they were observed throughout the urothelium with a gradient decreasing from luminal to basal in intensity. In conclusion, the human urothelium carries multiple cholinergic receptor subtypes, with predominant expression of M2R, M3R and alpha7-nAChR. Their distribution as well as that of the less expressed subtypes is layer-specific in the urothelium. In view of the multiplicity of pathways to which different cholinergic receptor subtypes are coupled, we propose that this layer-specific distribution serves to stratify cholinergic regulation of human urothelial function.
Bschleipfer
Thomas
T
Department of Urology and Pediatric Urology, Justus-Liebig-University, Rudolf-Buchheim-Str. 7, D-35385 Giessen, Germany.
Schukowski
Konstantin
K
Weidner
Wolfgang
W
Grando
Sergei A
SA
Schwantes
Ulrich
U
Kummer
Wolfgang
W
Lips
Katrin S
KS
D000368:Aged; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D043643:Receptor, Muscarinic M1 / Q000235:genetics / Q000378:metabolism; D043585:Receptor, Muscarinic M2 / Q000235:genetics / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000235:genetics / Q000378:metabolism; D043588:Receptor, Muscarinic M4 / Q000235:genetics / Q000378:metabolism; D043642:Receptor, Muscarinic M5 / Q000235:genetics / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000235:genetics* / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019459:Urothelium / Q000737:chemistry / Q000378:metabolism*
D021122:Protein Subunits; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D043588:Receptor, Muscarinic M4; D043642:Receptor, Muscarinic M5; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic