Inhibition of the beta3 subunit of l-type ca2+ channels

Abstract

The present invention provides reagents and methods for identifying inhibitors of the L-type Ca 2+ channel β 3 protein, which has been demonstrated to be involved in calcium signaling, insulin secretion, and glucose homeostasis. The invention also provides therapeutics and methods for treating a subject with one or more of diabetes, insulin resistance, impaired insulin secretion, and impaired glucose homeostasis, involving the use of inhibitors of an L-type Ca 2+ channel β 3 subunit to provide a benefit to the subject.

We claim: 
     
         1 . A recombinant host cell, wherein the host cell has been transfected with a recombinant expression vector comprising nucleic acid control sequences operatively linked to an L-type Ca 2+  channel β 3  gene, wherein the host cell does not possess functional β 3  subunit-containing L-type Ca 2+  channels. 
     
     
         2 . The recombinant host cell of  claim 1  wherein the host cell is a mammalian cell. 
     
     
         3 . A method for identifying inhibitors of the L-type Ca 2+  channel β 3  protein, comprising:
 a) providing the recombinant host cells of  claim 1 ; 
 b) contacting the recombinant host cells with a calcium indicator that emits detectable signals in the presence of calcium; 
 c) treating the host cells with one or more test compounds, wherein the treating occurs before, simultaneous with, or after the contacting of the host cells with the calcium indicator; 
 d) stimulating the recombinant host cells with an amount of ATP that is effective to increase intracellular calcium concentration in control cells; and 
 e) detecting signals from the calcium indicator in the recombinant host cells, 
 
       wherein a test compound-induced increase in the signals from the calcium indicator in the recombinant host cells indicates that the test compound is an inhibitor of the L-type Ca 2+  channel β 3  protein. 
     
     
         4 . The method of  claim 3 , wherein the method is used to identify compounds for use in treating one or more disorders selected from the group consisting of diabetes, insulin resistance, impaired insulin secretion, and impaired glucose homeostasis 
     
     
         5 . The method of  claim 3  wherein the recombinant host cells are mammalian cells 
     
     
         6 . A method for treating a subject with one or more disorders selected from the group consisting of diabetes, insulin resistance, impaired insulin secretion, and impaired glucose homeostasis, comprising administering to the subject one or more inhibitors of an L-type Ca 2+  channel β 3  subunit to provide a benefit to the subject. 
     
     
         7 . The method of  claim 6  wherein the one or more inhibitors of the L-type Ca 2+  channel β 3  subunit is identified according to the method of  claim 3 . 
     
     
         8 . The method of  claim 7  wherein the one or more inhibitors of the L-type Ca 2+  channel β 3  subunit comprises a compound selected from the group consisting of an antibody specific for the L-type Ca 2+  channel β 3  subunit; an antisense oligonucleotide directed against the L-type Ca 2+  channel β 3  subunit gene; and a small interfering RNA directed against the L-type Ca 2+  channel β 3  subunit gene.