Expression of a cloned rat histamine H2 receptor mediating inhibition of arachidonate release and activation of cAMP accumulation.

Abstract

A DNA, cloned after screening a rat genomic bank with probes derived from the sequence of a putative dog histamine H2 receptor [Gantz, I., Schiffer, M., Delvalle, J., Logsdon, C., Campbell, V., Uhler, M. & Yamada, T. (1991) Proc. Nad. Acad. Sci. USA 88,[429][430][431][432][433], was used to prepare a probe for Northern blot analysis and to transfect Chinese hamster ovary (CHO) cells. Distribution of the gene transcripts in guinea pig tissues was consistent with that of H2 receptors. Transfected CHO cells expressed a high density of sites binding [125I]iodoaminopotentidine, a selective H2-receptor ligand.These sites were characterized as typical H2 receptors by using a series of competing agents that displayed apparent dissociation constants closely similar to corresponding values at a reference biological system. In transfected cells, histamine stimulated, with high potency and large receptor reserve, the accumulation of cAMP. In addition, in the same cells, histamine potently inhibited the release of arachidonic acid induced either by stimulation of constitutive purinergic receptors or by application of a Ca2+ ionophore. This inhibition was independent of either cAMP or Ca2+ levels. The results suggest that a single H2 receptor may be linked not only to adenylyl cyclase activation but also to reduction of phospholipase A2 activity.Because HI receptors have been reported to stimulate arachidonic acid release, inhibition of this release, an unexpected signaling pathway for H2 receptors, may account for the opposing physiological responses elicited in many tissues by stimulation of these two receptor subtypes.Histamine (HA), a ubiquitous cell-to-cell messenger, exerts its numerous actions in the nervous, endocrine, and immune systems through interaction with three pharmacologically distinct receptor subtypes, termed H1, H2, and H3 (1, 2). H1 and H2 receptors are positively coupled to phospholipase C and adenylyl cyclase, respectively, whereas the intracellular signaling system of the H3 receptor is still unknown (3-5).In contrast to membrane receptors for other monoamines, molecular studies of HA receptors have just begun (6). For instance, H2-receptor peptides were identified in guinea pig brain by photoaffinity labeling (7) and, recently, canine (8) and human (9) H2-receptor genes have been cloned. Transfection of mammalian cells with these intronless genes resulted in the expression ofboth [3H]tiotidine binding sites and HA-sensitive adenylyl cyclase activity. Preliminary pharmacological characterizations of these receptors have been reported (8,9).Because molecular biological studies progressively reveal a much greater heterogeneity among receptor subtypes than previously thought (10, 11), we felt it of interest to identify and characterize receptors related to those described by Gantz et al. (8 [125I]Iodoaminopotentidine (125I-APT) was synthesized as described (7). The drugs and their sources were as follows: cimetidine, burimamide, metiamide, and dimaprit (Smith Kline & French); famotidine (Merck Sha...

Increases in intracellular calcium via activation of an endogenous P2‐purinoceptor in cultured CHO‐K1 cells

“…However, a constitutive ATP receptor linked to arachidonic acid release has been reported (Felder et al, 1991;Traiffort et al, 1992). We now present evidence for the existence of a purinoceptor linked to the mobilisation of [Ca2+]i in the Chinese hamster ovary cell line clone, CHO-KI.…”

Membrane organization and function of M1 and M23 isoforms of aquaporin-4 in epithelial cells

“…Conformational changes of AQP4 and OAPs were not examined in this study, however. Intracellular cAMP levels and subsequent activation of PKA in gastric glands have been reported also (5,9,13,36). The role of AQP4 in parietal cells is unclear, but HCl secretion by these cells may be associated with water transport to produce a secreted fluid that is isotonic with plasma.…”

International Union of Basic and Clinical Pharmacology. XCVIII. Histamine Receptors

“…30) in the basal ganglia, hippocampus, amygdala, and cerebral cortex (Traiffort et al, 1992b). Lowest densities were detected in cerebellum and hypothalamus.…”

“…The red nucleus expresses high levels of H 2 receptor mRNA. In peripheral rat organs, the stomach expresses the highest amounts of H 2 receptor mRNA (Traiffort et al, 1992b).…”