Type-specific inositol 1,4,5-trisphosphate receptor localization in the vomeronasal organ and its interaction with a transient receptor potential channel, TRPC2.
The vomeronasal organ (VNO) is the receptor portion of the accessory olfactory system and transduces chemical cues that identify social hierarchy, reproductive status, conspecifics and prey. Signal transduction in VNO neurons is apparently accomplished via an inositol 1,4,5-trisphosphate (IP3)-activated calcium conductance that includes a different set of G proteins than those identified in vertebrate olfactory sensory neurons. We used immunohistochemical (IHC) and SDS-PAGE/western analysis to localize three IP3 receptors (IP3R) in the rat VNO epithelium. Type-I IP3R expression was weak or absent. Antisera for type-II and -III IP3R recognized appropriate molecular weight proteins by SDS-PAGE, and labeled protein could be abolished by pre-adsorption of the respective antibody with antigenic peptide. In tissue sections, type-II IP3R immunoreactivity was present in the supporting cell zone but not in the sensory cell zone. Type-III IP3R immunoreactivity was present throughout the sensory zone and overlapped that of transient receptor potential channel 2 (TRPC2) in the microvillar layer of sensory epithelium. Co-immunoprecipitation of type-III IP3R and TRPC2 from VNO lysates confirmed the overlapping immunoreactivity patterns. The protein-protein interaction complex between type-III IP3R and TRPC2 could initiate calcium signaling leading to electrical signal production in VNO neurons.
Brann
Jessica H
JH
Program in Neuroscience and Molecular Biophysics, Biomedical Research Facility, Department of Biological Science, Florida State University, Tallahassee, Florida 32306, USA.
Dennis
John C
JC
Morrison
Edward E
EE
Fadool
Debra A
DA
D000818:Animals; D015153:Blotting, Western; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007150:Immunohistochemistry; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels; D046911:Macromolecular Substances; D008297:Male; D008565:Membrane Proteins; D009928:Organ Specificity / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D050053:TRPM Cation Channels; D019147:Vomeronasal Organ / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*
D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007473:Ion Channels; D046911:Macromolecular Substances; D008565:Membrane Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human