Acetylcholine is an autocrine or paracrine hormone synthesized and secreted by airway bronchial epithelial cells.
The role of acetylcholine (ACh) as a key neurotransmitter in the central and peripheral nervous system is well established. However, the role of ACh may be broader because ACh may also function as an autocrine or paracrine signaling molecule in a variety of nonneuronal tissues. To begin to establish ACh of nonneuronal origin as a paracrine hormone in lung, we have examined neonatal and adult monkey bronchial epithelium for the components involved in nicotinic cholinergic signaling. Using immunohistochemistry and RT-PCR, we have demonstrated in lung bronchial epithelial cells (BECs) expression of choline acetyltransferase, the vesicular ACh transporter, the choline high-affinity transporter, alpha7, alpha4, and beta2 nicotinic ACh receptor (nAChR) subunits, and the nAChR accessory protein lynx1. Confocal microscopy demonstrates that these factors are expressed in epithelial cells and are clearly distinct from neighboring nerve fibers. Confirmation of RNA identity has been confirmed by partial sequence analysis of PCR products and by cDNA cloning. Primary culture of BECs confirms the synthesis and secretion of ACh and the activity of cholinesterases. Thus, ACh meets all the criteria for an autocrine/paracrine hormone in lung bronchial epithelium. The nonneuronal cholinergic signaling pathway in lung provides a potentially important target for cholinergic drugs. This pathway may also explain some of the effects of nicotine on fetal development and also provides additional mechanisms by which smoking affects lung cancer growth and development.
Proskocil
Becky J
BJ
Division of Neuroscience, Oregon National Primate Research Center, 505 Northwest 185th Avenue, Beaverton, Oregon 97006, USA.
Sekhon
Harmanjatinder S
HS
Jia
Yibing
Y
Savchenko
Valentina
V
Blakely
Randy D
RD
Lindstrom
Jon
J
Spindel
Eliot R
ER
D000109:Acetylcholine / Q000096:biosynthesis* / Q000378:metabolism*; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001980:Bronchi / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000032:analysis / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism; D007150:Immunohistochemistry; D008253:Macaca mulatta; D026901:Membrane Transport Proteins / Q000032:analysis / Q000235:genetics; D018613:Microscopy, Confocal; D009479:Neuropeptides / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D011978:Receptors, Nicotinic / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D026901:Membrane Transport Proteins; D009479:Neuropeptides; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; C065637:choline transporter; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine