CREB, AP-1, ternary complex factors and MAP kinases connect transient receptor potential melastatin-3 (TRPM3) channel stimulation with increased c-Fos expression.
OBJECTIVE
The rise in intracellular Ca(2+) stimulates the expression of the transcription factor c-Fos. Depending on the mode of entry of Ca(2+) into the cytosol, distinct signal transducers and transcription factors are required. Here, we have analysed the signalling pathway connecting a Ca(2+) influx via activation of transient receptor potential melastatin-3 (TRPM3) channels with enhanced c-Fos expression.


METHODS
Transcription of c-Fos promoter/reporter genes that were integrated into the chromatin via lentiviral gene transfer was analysed in HEK293 cells overexpressing TRPM3. The transcriptional activation potential of c-Fos was measured using a GAL4-c-Fos fusion protein.


RESULTS
The signalling pathway connecting TRPM3 stimulation with enhanced c-Fos expression requires the activation of MAP kinases. On the transcriptional level, three Ca(2+) -responsive elements, the cAMP-response element and the binding sites for the serum response factor (SRF) and AP-1, are essential for the TRPM3-mediated stimulation of the c-Fos promoter. Ternary complex factors are additionally involved in connecting TRPM3 stimulation with the up-regulation of c-Fos expression. Stimulation of TRPM3 channels also increases the transcriptional activation potential of c-Fos.


CONCLUSIONS
Signalling molecules involved in connecting TRPM3 with the c-Fos gene are MAP kinases and the transcription factors CREB, SRF, AP-1 and ternary complex factors. As c-Fos constitutes, together with other basic region leucine zipper transcription factors, the AP-1 transcription factor complex, the results of this study explain TRPM3-induced activation of AP-1 and connects TRPM3 with the biological functions regulated by AP-1.
Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.
Sandra
S
Rubil
Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.
Oliver G
OG
Rössler
Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.
Gerald
G
Thiel
D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D005786:Gene Expression Regulation; D016762:Genes, fos / Q000187:drug effects / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011284:Pregnenolone / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000378:metabolism*; D050801:Ternary Complex Factors / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism*
C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D050053:TRPM Cation Channels; C475667:TRPM3 protein, human; D050801:Ternary Complex Factors; D018808:Transcription Factor AP-1; D011284:Pregnenolone; D020928:Mitogen-Activated Protein Kinases