Multiplex image-based autophagy RNAi screening identifies SMCR8 as ULK1 kinase activity and gene expression regulator

Jennifer Jung, Arnab Nayak, Véronique Schaeffer, Tatjana Starzetz, Achim K. Kirsch, Stefan Müller, Ivan Dikic, Michel Mittelbronn, Christian Behrends*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

56 Citations (Scopus)

Abstract

Autophagy is an intracellular recycling and degradation pathway that depends on membrane trafficking. Rab GTPases are central for autophagy but their regulation especially through the activity of Rab GEFs remains largely elusive. We employed a RNAi screen simultaneously monitoring different populations of autophagosomes and identified 34 out of 186 Rab GTPase, GAP and GEF family members as potential autophagy regulators, amongst them SMCR8. SMCR8 uses overlapping binding regions to associate with C9ORF72 or with a C9ORF72-ULK1 kinase complex holo-assembly, which function in maturation and formation of autophagosomes, respectively. While focusing on the role of SMCR8 during autophagy initiation, we found that kinase activity and gene expression of ULK1 are increased upon SMCR8 depletion. The latter phenotype involved association of SMCR8 with the ULK1 gene locus. Global mRNA expression analysis revealed that SMCR8 regulates transcription of several other autophagy genes including WIPI2. Collectively, we established SMCR8 as multifaceted negative autophagy regulator.

Original languageEnglish
Article numbere23063
JournaleLife
Volume6
DOIs
Publication statusPublished - 14 Feb 2017
Externally publishedYes

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