Intracellular Ca2+ stores modulate SOCCs and NMDA receptors via tyrosine kinases in rat hippocampal neurons.
The regulation of intracellular Ca(2+) signalling by phosphorylation processes remains poorly defined, particularly with regards to tyrosine phosphorylation. Evidence from non-excitable cells implicates tyrosine phosphorylation in the activation of so-called store-operated Ca(2+) channels (SOCCs), but their involvement in neuronal Ca(2+) signalling is still elusive. In the present study, we determined the role of protein tyrosine kinases (PTKs) and tyrosine phosphatases (PTPs) in the coupling between intracellular Ca(2+) stores and SOCCs in neonatal rat hippocampal neurons by Fura-2 Ca(2+) imaging. An early Ca(2+) response from intracellular stores was triggered with thapsigargin, and followed by a secondary plasma membrane Ca(2+) response. This phase was blocked by the non-specific Ca(2+) channel blocker NiCl and the SOCC blocker, 2-aminoethoxydiphenyl borate (2-APB). Interestingly, two structurally distinct PTK inhibitors, genistein and AG126, also inhibited this secondary response. Application of the PTP inhibitor sodium orthovanadate (OV) also activated a sustained and tyrosine kinase dependent Ca(2+) response, blocked by NiCl and 2-APB. In addition, OV resulted in a Ca(2+) store dependent enhancement of NMDA responses, corresponding to, and occluding the signalling pathway for group I metabotropic glutamate receptors (mGluRs). This study provides first evidence for tyrosine based phospho-regulation of SOCCs and NMDA signalling in neurons.
School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
David J
DJ
Koss
Gernot
G
Riedel
Bettina
B
Platt
D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D006624:Hippocampus / Q000201:enzymology / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D001896:Boron Compounds; D015220:Calcium Channels; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D014638:Vanadates; D016202:N-Methylaspartate; D011189:Potassium Chloride; D019284:Thapsigargin; D019833:Genistein; C109986:2-aminoethoxydiphenyl borate; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases; D002118:Calcium