Assay methods and compositions for detecting and evaluating the intracellular transduction of an extracellular signal

A method for identifying compounds that modulate cell surface protein-mediated activity by detecting intracellular transduction of a signal generated upon interaction of the compound with a cell surface protein, comprising:

• comparing the amount of transcription of a reporter gene or the amount of reporter gene product expressed in a first recombinant cell in the presence of the compound with the amount of transcription or product in a second recombinant cell;
• and
• selecting compounds that change the amount of transcription of a reporter gene or the amount of reporter gene product expressed in the first recombinant cell in the presence of the compound compared to the amount of transcription or product in the absence of the compound, or compared to the amount of transcription or product in the second recombinant cell, wherein:
• the first recombinant cell contains a reporter gene construct and expresses the cell surface protein;
• the second recombinant cell is identical to the first recombinant cell, except that it does not express the cell surface protein;
• and
• the reporter gene construct contains:
• (a) a transcriptional control element that is responsive to the intracellular signal that is generated by the interaction of an agonist with the cell surface protein;
• and
• (b) a reporter gene that encodes a detectable transcriptional or translational product and that is in operative association with the transcriptional control element. Transcription based assays that identify extracellular signals that modulate the activity of cell surface proteins are provided. Extracellular signals are identified by measuring the amount of transcription of a reporter gene in a recombinant cell that expresses the cell surface protein and contains DNA encoding the reporter gene under the transcriptional control of a promoter that is regulated, directly or indirectly, by the cell surface protein. The assays, provide a means for identifying potential pharmaceutical compounds that can be used to treat disease by virtue of their agonistic or antagonistic effects on the cell surface protein. Recombinant cells that express cell surface receptors and that contain reporter gene constructs that include transcriptional regulatory elements that are responsive to the activity of the cell surface receptors are also provided.