Enhanced potency of nucleotide-dendrimer conjugates as agonists of the P2Y14 receptor: multivalent effect in G protein-coupled receptor recognition.
The P2Y(14) receptor is a G protein-coupled receptor activated by uridine-5'-diphosphoglucose and other nucleotide sugars that modulates immune function. Covalent conjugation of P2Y(14) receptor agonists to PAMAM (polyamidoamine) dendrimers enhanced pharmacological activity. Uridine-5'-diphosphoglucuronic acid (UDPGA) and its ethylenediamine adduct were suitable functionalized congeners for coupling to several generations (G2.5-6) of dendrimers (both terminal carboxy and amino). Prosthetic groups, including biotin for avidin complexation, a chelating group for metal complexation (and eventual magnetic resonance imaging), and a fluorescent moiety, also were attached with the eventual goals of molecular detection and characterization of the P2Y(14) receptor. The activities of conjugates were assayed in HEK293 cells stably expressing the human P2Y(14) receptor. A G3 PAMAM conjugate containing 20 bound nucleotide moieties (UDPGA) was 100-fold more potent (EC(50) 2.4 nM) than the native agonist uridine-5'-diphosphoglucose. A molecular model of this conjugate docked in the human P2Y(14) receptor showed that the nucleotide-substituted branches could extend far beyond the dimensions of the receptor and be available for multivalent docking to receptor aggregates. Larger dendrimer carriers and greater loading favored higher potency. A similar conjugate of G6 with 147 out of 256 amino groups substituted with UDPGA displayed an EC(50) value of 0.8 nM. Thus, biological activity was either retained or dramatically enhanced in the multivalent dendrimer conjugates in comparison with monomeric P2Y(14) receptor agonists, depending on size, degree of substitution, terminal functionality, and attached prosthetic groups.
Das
Arijit
A
Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Zhou
Yixing
Y
Ivanov
Andrei A
AA
Carter
Rhonda L
RL
Harden
T Kendall
TK
Jacobson
Kenneth A
KA
D002478:Cells, Cultured; D050091:Dendrimers / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008968:Molecular Conformation; D011073:Polyamines / Q000737:chemistry / Q000494:pharmacology*; D058910:Purinergic P2 Receptor Agonists / Q000737:chemistry / Q000494:pharmacology*; D018048:Receptors, Purinergic P2 / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014535:Uridine Diphosphate Glucuronic Acid / Q000737:chemistry / Q000494:pharmacology*
D050091:Dendrimers; C518528:P2Y14 receptor, human; D011073:Polyamines; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D014535:Uridine Diphosphate Glucuronic Acid