RESEARCH ARTICLE


Minireview: Targeting GPCR Activated ERK Pathways for Drug Discovery



Haifeng Eishingdrelo1, *, Sathapana Kongsamut2
1 BioInvenu Corporation, 50 Williams Parkway, East Hanover, New Jersey, 07936, USA
2 Rudder Serendip LLC, 14 Coursen Way, Madison, New Jersey, 07940, USA


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© Eishingdrelo and Kongsamut; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the BioInvenu Corporation, 50 Williams Parkway, East Hanover, New Jersey, 07936 USA; Tel: 973-585-6777; Fax: 973-585-6776; E-mail: haifeng.eishingdrelo@bioinvenu.com


Abstract

It has become clear in recent years that multiple signal transduction pathways are employed upon GPCR activation. One of the major cellular effectors activated by GPCRs is extracellular signal-regulated kinase (ERK). Both G-protein and β-arrestin mediated signaling pathways can lead to ERK activation. However, depending on activation pathway, the subcellular destination of activated ERK1/2 may be different. G-protein -dependent ERK activation results in the translocation of active ERK to the nucleus, whereas ERK activated via an arrestin-dependent mechanism remains largely in the cytoplasm. The subcellular location of activated ERK1/2 determines the downstream signaling cascade. Many substrates of ERK1/2 are found in the nucleus: nuclear transcription factors that participate in gene transcription, cell proliferation and differentiation. ERK1/2 substrates are also found in cytosol and other cellular organelles: they may play roles in translation, mitosis, apoptosis and cross-talk with other signaling pathways. Therefore, determining specific subcellular locations of activated ERK1/2 mediated by GPCR ligands would be important in correlating signaling pathways with cellular physiological functions. While GPCR-stimulated selective ERK pathway activation has been studied in several receptor systems, exploitation of these different signaling cascades for therapeutics has not yet been seriously pursued. Many old drug candidates were identified from screens based on G-protein signaling assays, and their activity on β-arrestin signaling pathways being mostly unknown, especially regarding their subcellular ERK pathways. With today’s knowledge of complicated GPCR signaling pathways, drug discovery can no longer rely on single-pathway approaches. Since ERK activation is an important signaling pathway and associated with many physiological functions, targeting the ERK pathway, especially specific subcellular activation pathways should provide new avenues for GPCR drug discovery.

Keywords: GPCR, G-protein coupled receptor, ERK, extracellular signal-regulated kinase, nucleus, cytoplasm, subcellular localization, drug discovery.