Dataset Information

Polymorphisms of cardiac presynaptic alpha2C adrenergic receptors: Diverse intragenic variability with haplotype-specific functional effects.

ABSTRACT: The presynaptic alpha2C adrenergic receptors (AR) act to inhibit norepinephrine release in cardiac and other presynaptic nerves. We have recently shown that a genetic variant in the alpha2CAR coding region (Del322-325), which renders the receptor partially uncoupled from Gi, is a risk factor for heart failure. However, variability of heart failure phenotypes and a dominance of Del322-325 in those of African descent led us to hypothesize that other regions of this gene have functional polymorphisms. In a multiethnic population, we found 20 polymorphisms within 4,625 bp of contiguous sequence of this intronless gene encompassing the promoter, 5' UTR, coding, and 3' UTR. These polymorphisms occur in 24 distinct haplotypes with complex organizations, including multiple 5'-upstream polymorphisms in regions known to direct expression, a 3' UTR substitution polymorphism within an insertion/deletion sequence, and the radical coding polymorphism that deletes four amino acids. Relatively low linkage disequilibrium between many polymorphisms, few cosmopolitan haplotypes, prevalent ethnic-specific haplotypes, and substantial genetic divergence among haplotypes was noted. The dysfunctional Del322-325 allele was partitioned into multiple haplotypes, with frequencies of 48% to 2%. The functional implications of the haplotypes were ascertained by whole-gene transfections of human neuronal cells, where haplotype was significantly related (P < 0.001) to expression levels of receptor transcript and protein. Expression varied by as much as approximately 50% by haplotype, and such studies enabled haplotype clustering by phenotypic, rather than genotypic, similarities. Thus, depending on phenotype, expression-specific haplotypes may amplify, attenuate, or dominate the cardiomyopathic effect attributed to the alpha2CDel322-325 marker.

SUBMITTER: Small KM

PROVIDER: S-EPMC516511 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Polymorphisms of cardiac presynaptic alpha2C adrenergic receptors: Diverse intragenic variability with haplotype-specific functional effects.

Small Kersten M KM Mialet-Perez Jeanne J Seman Carrie A CA Theiss Cheryl T CT Brown Kari M KM Liggett Stephen B SB

Proceedings of the National Academy of Sciences of the United States of America 20040819 35

The presynaptic alpha2C adrenergic receptors (AR) act to inhibit norepinephrine release in cardiac and other presynaptic nerves. We have recently shown that a genetic variant in the alpha2CAR coding region (Del322-325), which renders the receptor partially uncoupled from Gi, is a risk factor for heart failure. However, variability of heart failure phenotypes and a dominance of Del322-325 in those of African descent led us to hypothesize that other regions of this gene have functional polymorphis ...[more]

PMID: 15319474

Similar Datasets

Project description:At the cell surface, ?ARs and endothelin receptors can regulate nitric oxide (NO) production. ?-adrenergic receptors (?ARs) and type B endothelin receptors (ETB) are present in cardiac nuclear membranes and regulate transcription. The present study investigated the role of the NO pathway in the regulation of gene transcription by these nuclear G protein-coupled receptors. Nitric oxide production and transcription initiation were measured in nuclei isolated from the adult rat heart. The cell-permeable fluorescent dye 4,5-diaminofluorescein diacetate (DAF2 DA) was used to provide a direct assessment of nitric oxide release. Both isoproterenol and endothelin increased NO production in isolated nuclei. Furthermore, a ?3AR-selective agonist, BRL 37344, increased NO synthesis whereas the ?1AR-selective agonist xamoterol did not. Isoproterenol increased, whereas ET-1 reduced, de novo transcription. The NO synthase inhibitor l-NAME prevented isoproterenol from increasing either NO production or de novo transcription. l-NAME also blocked ET-1-induced NO-production but did not alter the suppression of transcription initiation by ET-1. Inhibition of the cGMP-dependent protein kinase (PKG) using KT5823 also blocked the ability of isoproterenol to increase transcription initiation. Furthermore, immunoblotting revealed eNOS, but not nNOS, in isolated nuclei. Finally, caged, cell-permeable isoproterenol and endothelin-1 analogs were used to selectively activate intracellular ?-adrenergic and endothelin receptors in intact adult cardiomyocytes. Intracellular release of caged ET-1 or isoproterenol analogs increased NO production in intact adult cardiomyocytes. Hence, activation of the NO synthase/guanylyl cyclase/PKG pathway is necessary for nuclear ?3ARs to increase de novo transcription. Furthermore, we have demonstrated the potential utility of caged receptor ligands in selectively modulating signaling via endogenous intracellular G protein-coupled receptors.

Dataset Information

Polymorphisms of cardiac presynaptic alpha2C adrenergic receptors: Diverse intragenic variability with haplotype-specific functional effects.

Publications

Polymorphisms of cardiac presynaptic alpha2C adrenergic receptors: Diverse intragenic variability with haplotype-specific functional effects.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets