METHODS FOR IDENTIFYING AGENTS THAT TARGET LEAKS IN RYANODINE RECEPTORS
The present invention provides screening methods for identifying agents that enhance binding of a ryanodine receptor and its corresponding FKBP protein, such agents to be used in treating diseases associated with ryanodine receptors.
1 . An in vitro method for identifying a chemical compound that directly enhances binding of an FKBP protein to its corresponding ryanodine receptor (“RyR”), the method comprising:
(a) exposing the RyR to the FKBP protein in the presence or absence of a candidate chemical compound in vitro; and
(b) determining the amount of the RyR bound to the FKBP protein in the presence and absence of the compound, wherein an increased amount of RyR bound to the FKBP protein in the presence of the compound indicates that the compound directly enhances binding of the FKBP protein to the RyR; thereby
(c) identifying the compound as a compound that directly enhances binding of the FKBP protein to the RyR.
2 . The method of claim 1 , wherein step (a) comprises:
(i) immobilizing one of the FKBP protein or the RyR onto a solid phase;
(ii) contacting the other of the FKBP protein or the RyR with the solid phase; and
(iii) incubating the FKBP protein and the RyR in the presence or absence of a candidate chemical compound in vitro.
3 . The method of claim 2 , wherein the FKBP protein is immobilized.
4 . The method of claim 2 , wherein the RyR is immobilized.
5 . The method of claim 1 , wherein the RyR is PKA-phosphorylated as a result of disease state or in vitro PKA phosphorylation.
6 . The method of claim 1 , wherein the RyR is a RyR mutant that has low affinity for its corresponding FKBP protein.
7 . The method of claim 6 , wherein the RyR mutant is selected from the group consisting of RyR2-S2808D and RyR1-S2844D.
8 . The method of claim 2 , wherein the solid phase is a plate, a bead, a column or a combination thereof.
9 . The method of claim 8 , wherein the solid phase is a multi-well plate for high throughput screening.
10 . The method of claim 9 , wherein a predetermined number of wells on the multi-well plate contain no candidate chemical compound, and wherein other wells on said multi-well plate each contain one candidate chemical compound.
11 . The method of claim 10 , wherein the amount of the RyR bound to the FKBP protein in each well is determined by an automated plate reader.
12 . The method of claim 1 , wherein the RyR is radio-labeled or labeled with a fluorescent label.
13 . The method of claim 12 , wherein the RyR is radio-labeled with 3 H-ryanodine, 35 S, 32 P, 3 H, 14 C or 125 I.
14 . The method of claim 3 , wherein the RyR is radio-labeled or labeled with a fluorescent label.
15 . The method of claim 1 , wherein the RyR is RyR1 or RyR3 and the FKBP protein is FKBP12.
16 . The method of claim 3 , wherein the RyR is RyR1 or RyR3 and the FKBP protein is FKBP12.
17 . The method of claim 3 , wherein the RyR is RyR2 and the FKBP protein is FKBP12.6.
18 . The method of claim 4 , wherein the RyR is RyR1 or RyR3 and the FKBP protein is FKBP12.
19 . The method of claim 1 , wherein binding of the RyR and the FKBP protein is detected by using an RyR-binding agent.
20 . The method of claim 19 , wherein the RyR-binding agent is an anti-RyR antibody.