Cloning and pharmacological characterization of the guinea pig P2X7 receptor orthologue.
OBJECTIVE
The human, rat, and mouse P2X(7) receptors have been previously characterized, and in this study we report the cloning and pharmacological properties of the guinea pig orthologue.


METHODS
A cDNA encoding for the guinea pig P2X(7) receptor was isolated from a guinea pig brain library. The receptor was expressed in U-2 OS cells using the BacMam viral expression system. A monoclonal antibody was used to confirm high levels of cell surface expression and the functional properties were determined in ethidium bromide accumulation studies.


RESULTS
The predicted guinea pig protein is one amino acid shorter than the human and rat orthologues and over 70% identical to the rat and human receptors. In contrast to human and rat P2X(7) receptors, 2'-&3'-O-(4benzoylbenzoyl)ATP (BzATP) was a partial agonist of the guinea pig P2X(7) receptor when compared to ATP and acted as an antagonist in some assays. However, as at other species orthologues, BzATP was more potent than ATP. The guinea pig P2X(7) receptor possessed higher affinity for 1-[N,O-bis(5-isoquinoline sulphonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62), suramin and Coomassie Brilliant Blue than human or rat P2X(7) receptors suggesting that it is pharmacologically different to other rodent or human P2X(7) receptors.


CONCLUSIONS
The guinea pig recombinant P2X(7) receptor displays a number of unique properties that differentiate it from the human, rat and mouse orthologues and this structural and functional information should aid in our understanding of the interaction of agonists and antagonist with the P2X(7) receptor.
Neurology & GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Research & Development Limited, New Frontiers Science Park, Harlow, Essex, UK. Elena.2.Fonfria@gsk.com
E
E
Fonfria
W C
WC
Clay
D S
DS
Levy
J A
JA
Goodwin
S
S
Roman
G D
GD
Smith
J P
JP
Condreay
A D
AD
Michel
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D006168:Guinea Pigs; D006801:Humans; D051379:Mice; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000235:genetics; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes / Q000494:pharmacology; D013045:Species Specificity; D013498:Suramin / Q000494:pharmacology
C546468:P2RX7 protein, human; C546469:P2rx7 protein, mouse; C546470:P2rx7 protein, rat; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D013498:Suramin; C063302:KN 62; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; C004692:coomassie Brilliant Blue