Andrologie- Offener Zugang
Offener Zugang

Abstrakt

Margaret jones

Background: Nuclear Receptors (NRs) and G Protein Coupled Receptors (GPCRs) are two distinct but closely interregulated principal signal transduction pathways of eukaryotic cells. Androgen receptor (AR) and cAMP Responsive Element-Binding Protein (CREB), are classic Transcription Factor (TF) of NRs and GPCRs pathways, respectively. While emerging knowledges suggest functional interactions between the two TFs, detailed mechanistical study is lacking. Methods: Dynamic subcellular translocations of AR and CREB in response to activation of either and both signal pathways were studied in living cells using laser confocal microscopy. Transcriptional activities of the two TFs were assessed by activities of cognate target promoters. Results: AR and CREB resided in cytoplasm and nucleus, respectively, both in a diffuse manner, and both were transcriptionally silent, in the absence of androgen or PKA activation. AR translocated to subnuclear foci and became transcriptionally active in the presence of Dihydrotestosterone(DHT). CREB underwent similar subnuclear foci formation and transcriptional activation in the presence of PKA stimulator forskolin (FSK). In a subset of cells where AR resided diffusely in the nucleus in the absence of DHT, FSK translocated AR to subnuclear foci and rendered AR transcriptionally active. DHT translocated both AR and CREB to around 300 subnuclear foci where the two TFs co localized. This process led to transcriptional activation of AR but not CREB. Stimulation of cells with both FSK and DHT did not alter AR-CREB co localizing foci, though the DHT mediated AR transcriptional activity was enhanced whereas FSK-induced CREB transcriptional activity was reduced. Conclusion: Androgen-bound AR and PKA activated CREB are translocated to the identical subnuclear foci where the two TFs are subjected to mutual and differential cross-regulations such that CREB enhances DHT mediated AR transactivation whereas ligand-bound AR suppresses PKA induced CREB transactivation. Keywords: Androgen receptor; CREB; Transcription regulation; Subcellular localization; Live cells. Abbreviations: AR: Androgen Receptor; ARE: Androgen Responsive Element; CBP：CREB‐binding protein; CFP: Cyan Fluorescent Protein; CRE: cAMP Responsive Element; CREB: cAMP Responsive Element-Binding Protein; DHT: dihydrotestosteron; ER: Estrogen Receptor; FSK: forskolin; GFP: Green Fluorescent Protein; GPCR: G Protein Coupled Receptor; GR: Glucocorticoid Receptor; HSP: Heat Shock Protein; MMTV: Mouse Mammalian Tumor Virus; NLS: Nuclear Localization Signal; NR: Nuclear Receptor; SF1:Steroidogenic Factor 1; SRC1: Steroid Receptor Coactivator 1; TF: Transcription Factor; TIF 2:Transcriptional Intermediary Factor 2.