PKR kinase directly regulates tau expression and Alzheimer's disease-related tau phosphorylation

Lasse Reimer, Cristine Betzer, Rikke Hahn Kofoed, Christiane Volbracht, Karina Fog, Chaitanya Kurhade, Emma Nilsson, Anna K. Överby, Poul Henning Jensen

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Deposition of extensively hyperphosphorylated tau in specific brain cells is a clear pathological hallmark in Alzheimer's disease and a number of other neurodegenerative disorders, collectively termed the tauopathies. Furthermore, hyperphosphorylation of tau prevents it from fulfilling its physiological role as a microtubule-stabilizing protein and leaves it increasingly vulnerable to self-assembly, suggestive of a central underlying role of hyperphosphorylation as a contributing factor in the etiology of these diseases. Via in vitro phosphorylation and regulation of kinase activity within cells and acute brain tissue, we reveal that the inflammation associated kinase, protein kinase R (PKR), directly phosphorylates numerous abnormal and disease-modifying residues within tau including Thr181, Ser199/202, Thr231, Ser262, Ser396, Ser404 and Ser409. Similar to disease processes, these PKR-mediated phosphorylations actively displace tau from microtubules in cells. In addition, PKR overexpression and knockdown, respectively, increase and decrease tau protein and mRNA levels in cells. This regulation occurs independent of noncoding transcriptional elements, suggesting an underlying mechanism involving intra-exonic regulation of the tau-encoding microtubule-associated protein tau (MAPT) gene. Finally, acute encephalopathy in wild type mice, induced by intracranial Langat virus infection, results in robust inflammation and PKR upregulation accompanied by abnormally phosphorylated full-length- and truncated tau. These findings indicate that PKR, independent of other kinases and upon acute brain inflammation, is capable of triggering pathological modulation of tau, which, in turn, might form the initial pathologic seed in several tauopathies such as Alzheimer's disease and Chronic traumatic encephalopathy where inflammation is severe.

Original languageEnglish (US)
Pages (from-to)103-119
Number of pages17
JournalBrain Pathology
Volume31
Issue number1
DOIs
StatePublished - Jan 2021
Externally publishedYes

Keywords

  • PKR
  • Tau
  • neurodegeneration
  • neuroinflammation
  • tauopathies

ASJC Scopus subject areas

  • General Neuroscience
  • Pathology and Forensic Medicine
  • Clinical Neurology

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