Method of selecting novel immunosuppressant

1 . An agent for inhibiting IL-2 production and/or an agent for inhibiting immunocyte proliferation, each of which having low GATA-1 production inhibitory activity, comprising a selective HDAC4 and/or HDAC8 inhibitor.

2 . An agent for suppressing immunity having low thrombocytopenic activity, comprising a selective HDAC4 and/or HDAC8 inhibitor.

3 . A method of selecting an IL-2 production inhibitor and/or an immunocyte proliferation inhibitor which have low GATA-1 production inhibitory activity, which comprises measuring the HDAC4 and/or HDAC8 enzyme inhibitory activity of a test substance.

4 . A method of selecting an immunosuppressant having low thrombocytopenic activity, which comprises measuring the HDAC4 and/or HDAC8 enzyme inhibitory activity of a test substance.

5 . A method of selecting an immunosuppressant having low thrombocytopenic activity, which comprises steps (i) and (ii) below:

(i) measuring the HDAC4 and/or HDAC8 enzyme inhibitory activity of a test substance, and

(ii) measuring the HDAC enzyme inhibitory activity of the test substance, wherein the HDAC enzyme inhibitory activity is one or more HDAC enzyme inhibitory activities selected from a group consisting of HDAC1, HDAC2, HDAC3, HDAC5, HDAC6 and HDAC7 enzyme inhibitory activities.

6 . The method of claim 3 , which is a method of selecting an IL-2 production inhibitor and/or an immunocyte proliferation inhibitor which have low GATA-1 production inhibitory activity, and which comprises steps (i) to (iii) below, wherein the IL-2 production inhibitor and/or the immunocyte proliferation inhibitor selectively inhibits HDAC4 and/or HDAC8 enzyme activity:

(i) expressing each of the HDAC1, HDAC2, HDAC3, HDAC4, HDAC5, HDAC6, HDAC7 and HDAC8 genes to obtain respective enzyme solutions;

(ii) measuring HDAC enzyme activity for each of the enzyme solutions in the presence of a test substance;

(iii) selecting a test substance that selectively suppresses HDAC enzyme activity only when using an enzyme solution obtained by expressing the HDAC4 gene or the HDAC8 gene.

7 . The method of claim 4 , which is a method of selecting an immunosuppressant having low thrombocytopenic activity, and which comprises steps (i) to (iii) below, wherein the immunosuppressant selectively inhibits HDAC4 and/or HDAC8 enzyme activity:

(i) expressing each of the HDAC1, HDAC2, HDAC3, HDAC4, HDAC5, HDAC6, HDAC7 and HDAC8 genes to obtain respective enzyme solutions;

(ii) measuring.HDAC enzyme activity for each of the enzyme solutions in the presence of a test substance;

(iii) selecting a test substance that selectively suppresses HDAC enzyme activity only when using an enzyme solution obtained by expressing the HDAC4 gene or the HDAC8 gene.

8 . The method of claim 4 , which is a method of selecting an immunosuppressant having low thrombocytopenic activity, and which comprises steps (i) to (iii) below, wherein the immunosuppressant selectively inhibits HDAC4 and/or HDAC8 enzyme activity:

(i) measuring HDAC enzyme activity for an enzyme solution partially purified from human cells, in the presence of a test substance;

(ii) measuring HDAC enzyme activity for an enzyme solution obtained by expressing the HDAC4 gene and/or the HDAC8 gene, in the presence of a test substance;

(iii) selecting a test substance that selectively suppresses HDAC enzyme activity only when using an enzyme solution obtained by expressing the HDAC4 gene and/or the HDAC8 gene, by comparing the enzyme activities measured in (i) and (ii).

9 . A method of selecting an immunosuppressant having low thrombocytopenic activity, which comprises steps (i) to (iii) below, wherein an HDAC inhibitor that specifically inhibits the formation of a complex of HDAC4 and N-COR is selected from among test HDAC inhibitors:

(i) expressing the HDAC4 gene and the N-CoR gene to obtain an enzyme solution;

(ii) allowing the enzyme solution to coexist with a test HDAC inhibitor;

(iii) determining whether or not a complex of HDAC4 and N-CoR is formed in the mixture of enzyme solution and test HDAC inhibitor obtained in (ii).

10 . A method of selecting an immunosuppressant having low thrombocytopenic activity, which comprises steps (i) and (ii) below, wherein an HDAC inhibitor that specifically inhibits the formation of a complex of the HDAC4 fusion protein comprising at least a portion of the HDAC4 protein, and the N-CoR fusion protein comprising at least a portion of the N-COR protein, is selected from among test HDAC inhibitors:

(i) expressing the gene that encodes the HDAC4 fusion protein and the gene that encodes the N-CoR fusion protein in cells;

(ii) determining whether or not the test HDAC inhibitor inhibits the formation of a complex of the HDAC4 fusion protein and the N-COR fusion protein.

11 . A method of selecting a compound having low thrombocytopenic activity and having immunosuppressive activity, which comprises steps (i) and (ii) below, wherein an HDAC inhibitor that suppresses the expression level of HDAC4 and/or HDAC8 is selected from among test HDAC inhibitors:

(i) allowing cells that express HDAC4 and/or HDAC8 to coexist with a test HDAC inhibitors;

(ii) measuring the HDAC4 and/or HDAC8 expression level in the cells.

12 . A method of selecting a compound having low thrombocytopenic activity and having immunosuppressive activity, which comprises steps (i) and (ii) below, wherein an HDAC inhibitor that selectively inhibits the binding of HDAC4 and/or HDAC8 and an HDAC4- and/or HDAC8-specific ligand is selected from among test HDAC inhibitors:

(i) expressing the HDAC4 and/or HDAC8 gene to obtain an enzyme solution;

(ii) measuring the binding activity of the HDAC4 and/or HDAC8 enzyme and the HDAC4- and/or HDAC8-specific ligand for the enzyme solution in the presence of an HDAC4- and/or HDAC8-specific ligand and a test HDAC inhibitor.

13 . An assay kit for the selection of an immunosuppressant having low thrombocytopenic activity including. a selective HDAC4 and/or HDAC8 inhibitor, which includes at least (i) and (ii) below:

(i) enzyme solutions prepared by expressing each of the HDAC1, HDAC2, HDAC3, HDAC5, HDAC6 and HDAC7 genes;

(ii) an enzyme solution prepared by expressing each of the HDAC4 and/or HDAC8 gene.

14 . A DNA having the base sequence that encodes the amino acid sequence shown by SEQ ID NO:4 or SEQ ID NO:6.

15 . An HDAC4 variant that is the amino acid sequence shown by SEQ ID NO:4 or SEQ ID NO:6.

16 . A method of inhibiting IL-2 production and/or immunocyte proliferation with low GATA-1 production inhibitory activity, which comprises administering an effective amount of selective HDAC4 and/or HDAC8 inhibitor to a subject.

17 . A method of suppressing immunity with low thrombocytopenic activity, which comprises administering an effective amount of selective HDAC4 and/or HDAC8 inhibitor to a subject.

18 . Use of a selective HDAC4 and/or HDAC8 inhibitor for the production of an agent for inhibiting IL-2 production and/or an agent for inhibiting immunocyte proliferation which have low GATA-1 production inhibitory activity.

19 . Use of a selective HDAC4 and/or HDAC8 inhibitor for the production of an agent for suppressing immunity having low thrombocytopenic activity.