Identification of single nucleotide polymorphisms of the human metabotropic glutamate receptor 1 gene and pharmacological characterization of a P993S variant.
mGluR1 receptors are believed to play major roles in the pathophysiology of diseases such as anxiety and chronic pain and are being actively investigated as targets for drug development. Sequence polymorphisms can potentially influence the efficacy of drugs in patient populations and are therefore an important consideration in the drug development process. To identify DNA sequence variants of the mGluR1 receptor, comparative DNA sequencing was performed on DNA samples (n=186) from apparently healthy subjects representing two ethnic groups. In total, eight non-synonymous single nucleotide polymorphisms (SNPs) were identified and one SNP (c2977>T) was found to be particularly common, this SNP results in a proline to serine substitution at residue 993 (P993S). The WT (P993) and S993 variants were expressed in an inducible system which allowed us to titrate gene expression to equivalent levels and were pharmacologically characterized. We determined the potency and affinity of standard antagonist compounds as well as the potency and efficacy of the endogenous ligand glutamate and other agonist compounds at both receptor variants. Agonist evoked increases in intracellular Ca(2+) were measured by fluorometric imaging plate reader (FLIPR). The potency of mGluR1 antagonists was evaluated by their ability to inhibit quisqualate induced increases in intracellular Ca(2+), while their affinities were determined by radio-ligand binding studies. This study demonstrates that the Pro993Ser amino acid exchange is highly frequent in the human mGluR1 gene. This polymorphism however, does not appear to affect the potency of agonist compounds or the potencies or affinities of small molecule antagonist compounds.
Downey
Patrick M
PM
Schering-Plough Research Institute, Milan, Italy. patrick.downey@spcorp.com
Petrò
Roberta
R
Simon
Jason S
JS
Devlin
David
D
Lozza
Gianluca
G
Veltri
Alessio
A
Beltramo
Massimiliano
M
Bertorelli
Rosalia
R
Reggiani
Angelo
A
D019943:Amino Acid Substitution / Q000235:genetics*; D002460:Cell Line; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D014644:Genetic Variation / Q000235:genetics*; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D006801:Humans; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics*
D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D018698:Glutamic Acid