Molecular determinants and feedback circuits regulating type 2 CRH receptor signal integration
Danijela Markovic1, Anu Punn, Hendrik Lehnert
1Division of Endocrinology and Metabolism, Clinical Sciences Research Institute, Warwick Medical School, University of Warwick Gibbet Hill Road, Coventry, CV4 7AL, UK.
Biochimica Et Biophysica Acta
|February 23, 2011
Summary
The study reveals how corticotropin-releasing hormone receptor 2 (CRH-R2) signaling is fine-tuned by kinase pathways and receptor endocytosis, impacting cellular responses.
Area of Science:
- Cellular and Molecular Pharmacology
- Signal Transduction Pathways
- G Protein-Coupled Receptors
Background:
- The type 2 corticotropin-releasing hormone receptor (CRH-R2) mediates biological actions of urocortins and CRH through key signaling pathways.
- Understanding the molecular determinants of CRH-R2 signaling is crucial for deciphering its physiological roles.
Purpose of the Study:
- To investigate the molecular mechanisms underlying CRH-R2β signaling pathways in HEK293 cells.
- To elucidate the role of kinase pathways, G-proteins, and receptor endocytosis in CRH-R2β functional responses.
Main Methods:
- Utilized HEK293 cells overexpressing recombinant human CRH-R2β receptors.
- Employed specific kinase inhibitors and pertussis toxin to dissect signaling cascades.
- Investigated receptor trafficking, endocytosis, and protein-protein interactions.
Main Results:
- Urocortin 2 (Ucn 2) activated extracellular signal-regulated kinase (ERK) in a phosphoinositide 3-kinase (PI3-K) and cAMP/PKA-dependent manner.
- PKA-dependent association between AKAP250 and CRH-R2β was necessary for ERK activation.
- PKB/Akt activation involved pertussis toxin-sensitive G-proteins and PI3-K but not cAMP/PKA.
- Inhibition of PKA or ERK accelerated CRH-R2β endocytosis.
- ERK-mediated phosphorylation of β-arrestin1 modulated CRH-R2β internalization.
Conclusions:
- CRH-R2β signaling involves a complex interplay between kinase pathways (PKA, ERK, Akt) and receptor endocytosis.
- A negative feedback loop involving ERK and β-arrestin1 fine-tunes CRH-R2β responses.
- These intricate mechanisms regulate signal integration and receptor trafficking for precise cellular responses.
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