Novel steroid-activated nuclear receptors and uses therefor

A method of testing a compound for its ability to regulate transcription-activating effects of a SXR polypeptide, said method comprising assaying for the presence or absence of reporter protein upon contacting a host cell containing said SXR polypeptide and a reporter vector with said compound, wherein said reporter vector comprises:

• (a) a promoter that is operable in said host cell,
• (b) a response element, and
• (c) DNA encoding a reporter protein,
• wherein said DNA is operatively linked to said promoter for transcription of said DNA, and,
• wherein said promoter is operatively linked to said SXR response element for activation thereof.

A method of identifying compounds which activate SXR polypeptide, but do not activate other members of the steroid/thyroid hormone superfamily, said method comprising:

• (i) detecting in a first assay system the presence or absence of a first reporter protein upon contacting a first host cell with test compound(s), wherein said first host cell contains said SXR polypeptide and a first reporter vector, wherein said first reporter vector comprises:
• (a) a first promoter that is operable in said first host cell,
• (b) a SXR response element, and
• (c) a first DNA encoding a first reporter protein,
• wherein said first DNA is operatively linked to said first promoter for transcription of said first DNA, and,
• wherein said first promoter is operatively linked to said SXR response element for activation thereof;
• (ii) detecting in a second assay system the presence or absence of a second reporter protein upon contacting a second host cell with test compound(s), wherein said second host cell contains a member of the steroid/thyroid hormone superfamily other than SXR and a second reporter vector, wherein said second reporter vector comprises:
• (a) a second promoter that is operable in said second host cell,
• (b) a response element for said member of the steroid/thyroid hormone superfamily other than SXR, and
• (c) a second DNA encoding a second reporter protein,
• wherein said second DNA is operatively linked to said second promoter for transcription of said second DNA, and
• wherein said second promoter is operatively linked to said response element for said member of the steroid/thyroid hormone superfamily other than SXR for activation thereof;
• and
• (iii) identifying those compounds which induce production of a reporter protein in said first assay, but not in said second assay, as compounds which activate SXR polypeptide, but do not activate other members of the steroid/thyroid hormone superfamily.

Cells transfected with an isolated or recombinant polynucleotide, wherein said polynucleotide encodes a SXR polypeptide, or functional fragments thereof,

• wherein said SXR polypeptide is a member of the steroid/thyroid hormone superfamily and forms a heterodimer with retinoid X receptor,
• wherein said heterodimer binds to a direct or inverted repeat response element comprising at least two half sites RGBNNM separated by a spacer of 0 up to 15 nucleotides, wherein:
• R is selected from A or G;
• B is selected from G, C, or T;
• each N is independently selected from A, T, C, or G;
• and
• M is selected from A or C;
• with the proviso that at least 4 nucleotides of said RGBNNM sequence are identical with the nucleotides at corresponding positions of the sequence AGTTCA;
• and
• wherein said SXR polypeptide activates transcription of gene(s) under the control of cytochrome P450 response element in response to a wide variety of natural and synthetic steroid hormones, compounds that induce catabolic enzymes, steroid receptor agonists and antagonists, and bioactive dietary compounds.

An antibody which specifically binds to a SXR polypeptide, wherein said SXR polypeptide is a member of the steroid/thyroid hormone superfamily and forms a heterodimer with retinoid X receptor,

• wherein said heterodimer binds to a direct or inverted repeat response element comprising at least two half sites RGBNNM separated by a spacer of 0 up to 15 nucleotides, wherein:
• R is selected from A or G;
• B is selected from G, C, or T;
• each N is independently selected from A, T, C, or G;
• and
• M is selected from A or C;
• with the proviso that at least 4 nucleotides of said RGBNNM sequence are identical with the nucleotides at corresponding positions of the sequence AGTTCA;
• and
• wherein said SXR polypeptide activates transcription of gene(s) under the control of cytochrome P450 response element in response to a wide variety of natural and synthetic steroid hormones, compounds that induce catabolic enzymes, steroid receptor agonists and antagonists, and bioactive dietary compounds.