Affiliations: Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts at Lowell, Lowell, USA
Correspondence:
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Corresponding author: T.B. Shea, PhD. Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts at Lowell, One University Avenue, Lowell, MA 01854, USA, Tel.: +1 978 934 2881, Fax: +1 978 934 3044, E-mail: [email protected].
Abstract: Conflicting data has emerged documenting decreased and increased levels of phospho-tau following calcium influx. Calcium influx achieved by treatment of SH-SY-5Y human neuroblastoma with 1 µM calcium ionophore A23187 in the presence of 0.1 mM extracellular calcium depleted phospho-tau levels within 30 min. However, extending ionophore treatment to 60 min raised phospho-tau levels beyond that of control levels. Total tau levels were unchanged throughout these treatments, indicating that the reduction in PHF-1 reflected sequential alterations in tau phosphorylation rather than total tau. More rapid accumulation of phospho-tau accompanied treatment with increased concentrations of ionophore (3 µM) and extracellular calcium (0.9 mM). An inhibitor active against calcium-dependent kinase(s) prevented the increase in phospho-tau following calcium influx. These data underscore that phospho-tau levels represent the summation of kinase and phosphatase activities and indicate that net dephosphorylation or phosphorylation is dependent upon the extent and/or rate of calcium influx
