Calcium/calmodulin-activated phosphodiesterase expressed in olfactory receptor neurons.
We show that calmodulin-dependent phosphodiesterase (CAM-PDE) is selectively expressed in mature olfactory receptor neurons within the olfactory mucosa. Immunocytochemical staining reveals neuronal immunoreactivity that is most pronounced within cilia, dendritic knobs, and axon bundles. Neither sustentacular cells nor basal cells display immunoreactivity. The extent of loss of neuronal immunoreactivity following bulbectomy resembles loss of the neuronal population. High-affinity CAM-PDE activity in olfactory cilia is fivefold greater than in brain, when assayed at low micromolar cAMP. This activity is depleted in turbinates following bulbectomy. Olfactory mucosal PDE activity is composed of a minimum of two major forms. In the absence of Ca(2+), rolipram-sensitive PDE comprises 65% of total activity. Following stimulation by Ca2+, CAM-PDE activity is elevated sixfold to become the predominant form, thereby increasing total activity 300%, with half-maximal effect at 1 microM Ca2+. We propose that Ca2+ stimulation of CAM-PDE may be necessary for termination of olfactory signals.
Borisy
F F
FF
Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Ronnett
G V
GV
Cunningham
A M
AM
Juilfs
D
D
Beavo
J
J
Snyder
S H
SH
D000818:Animals; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D009297:Nasal Mucosa / Q000201:enzymology; D009833:Olfactory Pathways / Q000201:enzymology*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000201:enzymology*; D014018:Tissue Distribution
D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D010727:Phosphoric Diester Hydrolases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1