Pseudophosphorylation of tau at serine 422 inhibits caspase cleavage: In vitro evidence and implications for tangle formation in vivo

Angela L. Guillozet-Bongaarts, Michael E. Cahill, Vincent L. Cryns, Matthew R. Reynolds, Robert W. Berry, Lester I. Binder

Research output: Contribution to journalArticlepeer-review

115 Scopus citations

Abstract

The tangles of Alzheimer's disease (AD) are comprised of the tau protein displaying numerous alterations, including phosphorylation at serine 422 (S422) and truncation at aspartic acid 421 (D421). Truncation at the latter site appears to result from activation of caspases, a class of proteases that cleave specifically at aspartic acid residues. It has been proposed that phosphorylation at or near caspase cleavage sites could regulate the ability of the protease to cleave at those sites. Here, we use tau pseudophosphorylated at S422 (S422E) to examine the effects of tau phosphorylation on its cleavage by caspase 3. We find that S422E tau is more resistant to proteolysis by caspase 3 than non-pseudophosphorylated tau. Additionally, we use antibodies directed against the phosphorylation site and against the truncation epitope to assess the presence of these epitopes in neurofibrillary tangles in the aged human brain. We show that phosphorylation precedes truncation during tangle maturation. Moreover, the distribution of the two epitopes suggests that a significant length of time (perhaps as much as two decades) elapses between S422 phosphorylation and cleavage at D421. We further conclude that tau phosphorylation at S422 may be a protective mechanism that inhibits cleavage in vivo.

Original languageEnglish
Pages (from-to)1005-1014
Number of pages10
JournalJournal of Neurochemistry
Volume97
Issue number4
DOIs
StatePublished - May 2006
Externally publishedYes

Keywords

  • Alzheimer's disease
  • Apoptosis
  • Neurofibrillary tangle
  • Neuropathology
  • Proteolysis

Fingerprint

Dive into the research topics of 'Pseudophosphorylation of tau at serine 422 inhibits caspase cleavage: In vitro evidence and implications for tangle formation in vivo'. Together they form a unique fingerprint.

Cite this