Proteasome failure promotes positioning of lysosomes around the aggresome via local block of microtubule-dependent transport

Nava Zaarur, Anatoli B. Meriin, Eloy Bejarano, Xiaobin Xu, Vladimir L. Gabai, Ana Maria Cuervo, Michael Y. Sherman

Research output: Contribution to journalArticle

42 Scopus citations


Ubiquitinated proteins aggregate upon proteasome failure, and the aggregates are transported to the aggresome. In aggresomes, protein aggregates are actively degraded by the autophagy-lysosome pathway, but why targeting the aggresome promotes degradation of aggregated species is currently unknown. Here we report that the important factor in this process is clustering of lysosomes around the aggresome via a novel mechanism. Proteasome inhibition causes formation of a zone around the centrosome where microtubular transport of lysosomes is suppressed, resulting in their entrapment and accumulation. Microtubule-dependent transport of other organelles, including autophagosomes, mitochondria, and endosomes, is also blocked in this entrapment zone (E-zone), while movement of organelles at the cell periphery remains unaffected. Following the whole-genome small interfering RNA (siRNA) screen for proteins involved in aggresome formation, we defined the pathway that regulates formation of the E-zone, including the Stk11 protein kinase, the Usp9x deubiquitinating enzyme, and their substrate kinase MARK4. Therefore, upon proteasome failure, targeting of aggregated proteins of the aggresome is coordinated with lysosome positioning around this body to facilitate degradation of the abnormal species.

Original languageEnglish (US)
Pages (from-to)1336-1348
Number of pages13
JournalMolecular and cellular biology
Issue number7
StatePublished - Apr 2014


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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