engleski

SH-SY5Y neuroblastoma cells treated with phosphatase inhibitor okadaic acid express high molecular weight tau species

One of the key features of early stages of Alzheimer’s disease abnormal phosphorylation of tau, a microtubule-associated protein. Tau hyperphosphorylation results from the activity of several protein kinases and downregulation of phosphatase PP2A. To study processes involving phosphorylated tau, cultured cells can be treated with okadaic acid(OA), an inhibitor that primarily targets phosphatase PP2A. Neuroblastoma SH-Y5Y cells express several splicing isoforms of tau and are useful as a cell culture model for investigating molecular pathways important for neuronal tissues due to their neuron-like characteristics. We found that: 1) SH-SY5Y cells treated with 100 nM okadaic acid express 100 kDa tau phosphorylated at Ser202 and Ser396, 2) 100 kDa-phospho-tau is present in the heat stable fraction of protein lysate, 3) Alkaline phosphatase treatment abolishes detection of 100kDa-phospho-tau by phospho-specific antibody, 4) 100 kDa phospho-tau is stable in buffers containing β-mercaptoethanol, urea or guanidine- hydrochloride, 5) SH-SY5Y cells treated with 20 nM OA express 100 kDa tau that is phosphorylated on Ser202, but very little on Ser396. Taken together, we found that treatment of SH-SY5Y cells with OA leads to expression of a 100 kDa protein reactive to anti-phospho-tau antibodies CP13 (ptau-Ser202) and pSer396 (ptau-Ser396). While not fully characterized, this protein may represent a phosphorylation-induced tau oligomer.

Alzheimer's disease ; tau protein ; neuroblastoma cell culture ; okadaic acid ; phospho-tau antibodies ; phosphatase PP2A ; tau oligomers

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