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Merck

A protein quality control pathway regulated by linear ubiquitination.

The EMBO journal (2019-03-20)
Eva M van Well, Verian Bader, Maria Patra, Ana Sánchez-Vicente, Jens Meschede, Nikolas Furthmann, Cathrin Schnack, Alina Blusch, Joseph Longworth, Elisabeth Petrasch-Parwez, Kohji Mori, Thomas Arzberger, Dietrich Trümbach, Lena Angersbach, Cathrin Showkat, Dominik A Sehr, Lena A Berlemann, Petra Goldmann, Albrecht M Clement, Christian Behl, Andreas C Woerner, Carsten Saft, Wolfgang Wurst, Christian Haass, Gisa Ellrichmann, Ralf Gold, Gunnar Dittmar, Mark S Hipp, F Ulrich Hartl, Jörg Tatzelt, Konstanze F Winklhofer
RESUMEN

Neurodegenerative diseases are characterized by the accumulation of misfolded proteins in the brain. Insights into protein quality control mechanisms to prevent neuronal dysfunction and cell death are crucial in developing causal therapies. Here, we report that various disease-associated protein aggregates are modified by the linear ubiquitin chain assembly complex (LUBAC). HOIP, the catalytic component of LUBAC, is recruited to misfolded Huntingtin in a p97/VCP-dependent manner, resulting in the assembly of linear polyubiquitin. As a consequence, the interactive surface of misfolded Huntingtin species is shielded from unwanted interactions, for example with the low complexity sequence domain-containing transcription factor Sp1, and proteasomal degradation of misfolded Huntingtin is facilitated. Notably, all three core LUBAC components are transcriptionally regulated by Sp1, linking defective LUBAC expression to Huntington's disease. In support of a protective activity of linear ubiquitination, silencing of OTULIN, a deubiquitinase with unique specificity for linear polyubiquitin, decreases proteotoxicity, whereas silencing of HOIP has the opposite effect. These findings identify linear ubiquitination as a protein quality control mechanism and hence a novel target for disease-modifying strategies in proteinopathies.