TY - JOUR
T1 - Akt/PKB kinase phosphorylates separately Thr212 and Ser214 of tau protein in vitro
AU - Ksiezak-Reding, Hanna
AU - Pyo, Han Kyoung
AU - Feinstein, Boris
AU - Pasinetti, Giulio M.
N1 - Funding Information:
The authors thank Drs. Gloria Lee and Michel Goedert for their generous gift of tau clones, Peter Seubert from Athena Neurosciences (San Francisco, CA) for providing 12E8 antibody, Peter Davies for providing antibody PHF-1, A. Van de Voorde and E. Vanmechelen from Innogenetics (Ghent, Belgium) for providing a panel of antibodies from the AT series, AT8, AT100, and AT180, and Michael J. Reding for critically reading the manuscript. This work was supported by the Alzheimer's Association (Zenith Award) and the Society for Progressive Supranuclear Palsy (Grant No. 411) to HKR.
PY - 2003/11/20
Y1 - 2003/11/20
N2 - Microtubule-associated protein tau contains a consensus motif for protein kinase B/Akt (Akt), which plays an essential role in anti-apoptotic signaling. The motif encompasses the AT100 double phospho-epitope (Thr212/Ser214), a specific marker for Alzheimer's disease (AD) and other neurodegenerations, raising the possibility that it could be generated by Akt. We studied Akt-dependent phosphorylation of tau protein in vitro. We found that Akt phosphorylated both Thr212 and Ser214 in the longest and shortest tau isoforms as determined using phospho site-specific antibodies against tau. Akt did not phosphorylate other tau epitopes, including Tau-1, AT8, AT180, 12E8 and PHF-1. The Akt-phosphorylated tau retained its initial electrophoretic mobility. Immunoprecipitation studies with phospho-specific Thr212 and Ser214 antibodies revealed that only one of the two sites is phosphorylated per single tau molecule, resulting in tau immunonegative for AT100. Mixed kinase studies showed that prior Ser214 phosphorylation by Akt blocked protein kinase A but not GSK3β activity. On the other hand, GSK3β selectively blocked Ser214 phosphorylation, which was prevented by lithium. The results suggest that Akt may be involved in AD-specific phosphorylation of tau at the AT100 epitope in conjunction with other kinases. Our data suggest that phosphorylation of tau by Akt may play specific role(s) in Akt-mediated anti-apoptotic signaling, particularly relevant to AD and other neurodegenerations.
AB - Microtubule-associated protein tau contains a consensus motif for protein kinase B/Akt (Akt), which plays an essential role in anti-apoptotic signaling. The motif encompasses the AT100 double phospho-epitope (Thr212/Ser214), a specific marker for Alzheimer's disease (AD) and other neurodegenerations, raising the possibility that it could be generated by Akt. We studied Akt-dependent phosphorylation of tau protein in vitro. We found that Akt phosphorylated both Thr212 and Ser214 in the longest and shortest tau isoforms as determined using phospho site-specific antibodies against tau. Akt did not phosphorylate other tau epitopes, including Tau-1, AT8, AT180, 12E8 and PHF-1. The Akt-phosphorylated tau retained its initial electrophoretic mobility. Immunoprecipitation studies with phospho-specific Thr212 and Ser214 antibodies revealed that only one of the two sites is phosphorylated per single tau molecule, resulting in tau immunonegative for AT100. Mixed kinase studies showed that prior Ser214 phosphorylation by Akt blocked protein kinase A but not GSK3β activity. On the other hand, GSK3β selectively blocked Ser214 phosphorylation, which was prevented by lithium. The results suggest that Akt may be involved in AD-specific phosphorylation of tau at the AT100 epitope in conjunction with other kinases. Our data suggest that phosphorylation of tau by Akt may play specific role(s) in Akt-mediated anti-apoptotic signaling, particularly relevant to AD and other neurodegenerations.
KW - AT100 epitope
KW - Akt/protein kinase B
KW - Alzheimer's disease
KW - Glycogen synthase kinase 3β
KW - Protein kinase A
KW - Tau
UR - http://www.scopus.com/inward/record.url?scp=0242409714&partnerID=8YFLogxK
U2 - 10.1016/j.bbadis.2003.09.001
DO - 10.1016/j.bbadis.2003.09.001
M3 - Article
C2 - 14636947
AN - SCOPUS:0242409714
SN - 0925-4439
VL - 1639
SP - 159
EP - 168
JO - Biochimica et Biophysica Acta - Molecular Basis of Disease
JF - Biochimica et Biophysica Acta - Molecular Basis of Disease
IS - 3
ER -