ERK signaling mediates CaSR-promoted axon growth

• Published in: Neuroscience letters Vol. 603; pp. 77 - 83
• Main Authors: Vizard, Thomas N., Newton, Michael, Howard, Laura, Wyatt, Sean, Davies, Alun M.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 31.08.2015; Elsevier Scientific Publishers Ireland
• Subjects: Animals; Axon growth; Axons - physiology; Cell Line; Development; Enzyme Activation; Extracellular calcium-sensing receptor; Extracellular-regulated kinase; Mice; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Nerve Growth Factor - metabolism; Receptors, G-Protein-Coupled - metabolism; Signal Transduction; Sympathetic neuron; Axon growth; Sympathetic neuron; Development; Extracellular calcium-sensing receptor; Extracellular-regulated kinase
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2015.07.019

•We have investigated how CaSR activation enhances sympathetic axon growth.•CaSR activation promotes phosphorylation of ERK1 and ERK2.•Inhibition of ERK1/ERK2 phosphorylation blocks CaSR-promoted axon growth.•CaSR-promoted axon growth requires a discrete region of the cytoplasmic domain. The extracellular calcium-sensing receptor (CaSR) is a G-protein coupled receptor that monitors the systemic extracellular free ionized calcium level ([Ca2+]o) in organs involved in systemic [Ca2+]o homeostasis. CaSR is widely expressed in the nervous system and its activation promotes axon and dendrite growth during development, but the mechanism by which it does this is not known. Here we show that enhanced axon growth and branching from cultured embryonic sympathetic neurons by activation of the endogenous CaSR depends on the presence of nerve growth factor (NGF). Our observation that activation of overexpressed CaSR promotes axon growth in NGF-free medium has enabled us to investigate CaSR downstream signaling contributing to axon growth in the absence of NGF signaling. We show that activation of overexpressed CaSR leads to activation of ERK1 and ERK2, and pharmacological inhibition of CaSR-dependent ERK1/ERK2 activation prevents CaSR-dependent axon growth. Analysis of axon growth from cultured neurons expressing deletion mutants of the CaSR cytoplasmic tail revealed that the region between alanine 877 and glycine 907 is required for promoting axon growth that is distinct from the high-affinity filamin-A binding site that has previously been implicated in ERK1/ERK2 activation.