Compositions, kits, and methods for identification, assessment, prevention, and therapy of metabolic disorders
The invention provides methods and compositions for selectively promoting anti-metabolic disorder activity over classical PPAR gamma activation through modulation of PPAR gamma phosphorylation (e.g., Ser-273 phosphorylation of murine peroxisome proliferator activated receptor gamma (PPAR gamma) 2 or a corresponding serine residue in a murine PPAR gamma 2 homolog, including a human). Also provided are methods for preventing, treating, or predictiving responsiveness of therapies for metabolic disorders in a subject through selective inhibition of such PPAR gamma phosphorylation. Further provided are methods for identifying compounds that are capable of modulating such PPAR gamma phosphorylation.
1. A method of identifying a compound which inhibits Ser-273 phosphorylation of murine PPAR gamma 2 or a corresponding serine residue in an ortholog of murine PPAR gamma 2 comprising:
a) contacting a sample comprising a murine PPAR gamma 2 polypeptide or an ortholog of murine PPAR gamma 2, wherein the murine PPAR gamma 2 polypeptide or an ortholog of murine PPAR gamma 2 comprises the sequence KTTDKSPFVIYDM (SEQ ID NO: 94) with a test compound; and determining the amount of Ser-273-phophorylated murine PPAR gamma 2 relative to total PPAR gamma 2, or the amount of the corresponding serine-phosphorylated ortholog of the murine PPAR gamma 2 relative to total PPAR gamma 2;
b) determining the amount of Ser-273-phophorylated murine PPAR gamma 2 relative to total PPAR gamma 2, or the amount of the corresponding serine-phosphorylated ortholog of the murine PPAR gamma 2 relative to total PPAR gamma 2 of a control;
c) comparing the Ser-273 phosphorylation in (a) and (b); and identifying a compound that inhibits or reduces said Ser-273 phosphorylation in (a) relative to (b).
2. The method of claim 1 , wherein the sample is selected from the group consisting of in vitro, ex vivo, and in vivo samples.
3. The method of claim 1 , wherein the control is the amount of Ser-273-phophorylated murine PPAR gamma 2 relative to total PPAR gamma 2, or the amount of the corresponding serine-phosphorylated ortholog of the murine PPAR gamma 2 relative to total PPAR gamma 2 of the sample in the absence of the test compound.
4. The method of claim 1 , wherein the control is the amount of Ser-273-phophorylated murine PPAR gamma 2 relative to total PPAR gamma 2, or the amount of the corresponding serine-phosphorylated ortholog of the murine PPAR gamma 2 relative to total PPAR gamma 2, of the sample contacted with a classical PPAR gamma 2 agonist.
5. The method of claim 1 , wherein the control is the amount of Ser-273-phophorylated murine PPAR gamma 2 relative to total PPAR gamma 2, or the amount of the corresponding serine-phosphorylated ortholog of the murine PPAR gamma 2 relative to total PPAR gamma 2, of the sample contacted with rosiglitazone under standard conditions.
6. The method of claim 1 , further comprising a step of determining whether the test compound directly binds the murine PPAR gamma 2 or the ortholog thereof.
7. The method of claim 1 , wherein the sample is from preadipocytes, mature white adipocytes, brown adipocytes, monocytes, or macrophages.
8. The method of claim 1 , wherein the sample is from an animal model of a metabolic disorder.
9. The method of claim 1 , wherein said PPAR gamma 2 is human PPAR gamma 2.
10. The method of claim 9 , wherein the sample is selected from the group consisting of in vitro, ex vivo, and in vivo samples.
11. The method of claim 9 , wherein inhibition of the serine residue of human PPAR gamma 2 corresponding to Ser-273 of murine PPAR gamma 2 is determined by analyzing the amount of the serine-phosphorylated human PPAR gamma 2.
12. The method of claim 9 , wherein inhibition of the serine residue of human PPAR gamma 2 corresponding to Ser-273 of murine PPAR gamma 2 is determined by analyzing the amount of the serine-phosphorylated human PPAR gamma 2, relative to total PPAR gamma 2 and comparing the ratio to a control.
13. The method of claim 9 , further comprising a step of determining whether the test compound directly binds human PPAR gamma 2.
14. The method of claim 1 , wherein said PPAR gamma is murine PPAR gamma 2.
15. The method of claim 14 , wherein the sample is selected from the group consisting of in vitro, ex vivo, and in vivo samples.
16. The method of claim 14 , wherein inhibition of said Ser-273 phosphorylation of PPAR gamma 2 is determined by analyzing the amount of Ser-273-phosphorylated murine PPAR gamma 2.
17. The method of claim 14 , wherein inhibition of Ser-273 phosphorylation is determined by analyzing the amount of Ser-273-phosphorylated murine PPAR gamma 2 relative to total PPAR gamma 2, and comparing the ratio to a control.
18. The method of claim 14 , further comprising a step of determining whether the test compound directly binds murine PPAR gamma 2.