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Open Access

Amyloid‐β oligomers induce synaptic damage via Tau‐dependent microtubule severing by TTLL6 and spastin

Hans Zempel, Julia Luedtke, Yatender Kumar, Jacek Biernat, Hana Dawson, Eckhard Mandelkow, Eva‐Maria Mandelkow

Author Affiliations

  1. Hans Zempel1,
  2. Julia Luedtke1,2,
  3. Yatender Kumar1,2,
  4. Jacek Biernat1,
  5. Hana Dawson3,
  6. Eckhard Mandelkow1,2,4 and
  7. Eva‐Maria Mandelkow*,1,2,4
  1. 1 DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany
  2. 2 MPI for Neurological Research, Hamburg Outstation, Hamburg, Germany
  3. 3 Duke University Medical Center, Durham, NC, USA
  4. 4 CAESAR Research Center, Bonn, Germany
  1. *Corresponding author. DZNE, German Center for Neurodegenerative Diseases, Ludwig‐Erhard‐Allee 2, Bonn 53175, Germany. Tel.:+49 228 43302 630; Fax:+49 228 43302 689; E‐mail: mandelkow{at}mpasmb.desy.de

Abstract

Mislocalization and aggregation of Aβ and Tau combined with loss of synapses and microtubules (MTs) are hallmarks of Alzheimer disease. We exposed mature primary neurons to Aβ oligomers and analysed changes in the Tau/MT system. MT breakdown occurs in dendrites invaded by Tau (Tau missorting) and is mediated by spastin, an MT‐severing enzyme. Spastin is recruited by MT polyglutamylation, induced by Tau missorting triggered translocalization of TTLL6 (Tubulin‐Tyrosine‐Ligase‐Like‐6) into dendrites. Consequences are spine loss and mitochondria and neurofilament mislocalization. Missorted Tau is not axonally derived, as shown by axonal retention of photoconvertible Dendra2‐Tau, but newly synthesized. Recovery from Aβ insult occurs after Aβ oligomers lose their toxicity and requires the kinase MARK (Microtubule‐Affinity‐Regulating‐Kinase). In neurons derived from Tau‐knockout mice, MTs and synapses are resistant to Aβ toxicity because TTLL6 mislocalization and MT polyglutamylation are prevented; hence no spastin recruitment and no MT breakdown occur, enabling faster recovery. Reintroduction of Tau re‐establishes Aβ‐induced toxicity in TauKO neurons, which requires phosphorylation of Tau's KXGS motifs. Transgenic mice overexpressing Tau show TTLL6 translocalization into dendrites and decreased MT stability. The results provide a rationale for MT stabilization as a therapeutic approach.

  • Received July 15, 2013.
  • Accepted August 22, 2013.

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