Selective G protein -subunit compositions mediate phospholipase C activation in the vomeronasal organ

Authors: Rünnenburger K.¹; Breer H.²; Boekhoff I.²

Source: European Journal of Cell Biology, Volume 81, Number 10, October 2002 , pp. 539-547(9)

Publisher: Urban & Fischer

Abstract:

Chemosensory neurons of the vomeronasal organ (VNO) are supposed to detect pheromones controlling social and reproductive behavior in most terrestrial vertebrates. Recent studies indicate that pheromone signaling in VNO neurons is mediated via phospholipase C (PLC) activation generating the two second messengers inositol-1,4,5-trisphosphate (IP₃) and diacylglycerol (DAG). Since G_i and G_o predominantly expressed in VNO neurons are usually not involved in activating PLC, it was explored if PLC activation may be mediated by G subunits. It was found that a scavenger for dimers reduced the urine-induced IP₃ formation in VNO preparations in a dose-dependent manner indicating a role for G complexes. Towards an identification of the relevant G and G subunit(s), PCR approaches as well as immunohistochemical experiments were performed. It was found that out of the five known G subtypes, only G₂ was expressed in both G_i as well as G_o neurons. Experimental approaches focusing on the spatial expression profile of identified G subtypes revealed that G₈-positive neurons are preferentially localized to the basal region of the vomeronasal epithelium, whereas G₂-reactive cells are restricted to the apical G_i-positive layer of the sensory epithelium. As IP₃ formation induced upon stimulation with volatile urinary compounds was selectively blocked by G₂-specific antibodies whereas second messenger formation elicited upon stimulation with _2u globulin was inhibited by antibodies recognizing G₈, it is conceivable that PLC activation in the two populations of chemosensory VNO neurons is mediated by different G complexes.

Keywords: G protein; complexes; signal transduction; vomeronasal organ; phospholipase C

Language: English

Document Type: Original article

DOI: http://dx.doi.org/10.1078/0171-9335-00277

Affiliations: 1: Department of Pharmacology and Toxicology, University of Ulm, Ulm/Germany 2: Institute of Physiology, University of Hohenheim, Stuttgart-Hohenheim/Germany

Publication date: 2002-10-01

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