FLCN, a novel autophagy component, interacts with GABARAP and is regulated by ULK1 phosphorylation

Elaine A. Dunlop, Sara Seifan, Tijs Claessens, Christian Behrends, Miriam A. F. Kamps, Ewelina Rozycka, Alain J. Kemp, Ravi K. Nookala, John Blenis, Barry J. Coull, James T. Murray, Maurice A. M. van Steensel, Simon Wilkinson, Andrew R. Tee (Lead / Corresponding author)

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant condition caused by mutations in the FLCN gene and characterized by benign hair follicle tumors, pneumothorax, and renal cancer. Folliculin (FLCN), the protein product of the FLCN gene, is a poorly characterized tumor suppressor protein, currently linked to multiple cellular pathways. Autophagy maintains cellular homeostasis by removing damaged organelles and macromolecules. Although the autophagy kinase ULK1 drives autophagy, the underlying mechanisms are still being unraveled and few ULK1 substrates have been identified to date. Here, we identify that loss of FLCN moderately impairs basal autophagic flux, while re-expression of FLCN rescues autophagy. We reveal that the FLCN complex is regulated by ULK1 and elucidate 3 novel phosphorylation sites (Ser406, Ser537, and Ser542) within FLCN, which are induced by ULK1 overexpression. In addition, our findings demonstrate that FLCN interacts with a second integral component of the autophagy machinery, GABA(A) receptor-associated protein (GABARAP). The FLCN-GABARAP association is modulated by the presence of either folliculin-interacting protein (FNIP)-1 or FNIP2 and further regulated by ULK1. As observed by elevation of GABARAP, sequestome 1 (SQSTM1) and microtubule-associated protein 1 light chain 3 (MAP1LC3B) in chromophobe and clear cell tumors from a BHD patient, we found that autophagy is impaired in BHD-associated renal tumors. Consequently, this work reveals a novel facet of autophagy regulation by ULK1 and substantially contributes to our understanding of FLCN function by linking it directly to autophagy through GABARAP and ULK1.

Original languageEnglish
Pages (from-to)1749-1760
Number of pages12
JournalAutophagy
Volume10
Issue number10
Early online date22 Jul 2014
DOIs
Publication statusPublished - 2014

Keywords

  • Autophagy
  • BHD
  • FLCN
  • GABARAP
  • MAP1LC3B
  • SQSTM1
  • ULK1

Fingerprint Dive into the research topics of 'FLCN, a novel autophagy component, interacts with GABARAP and is regulated by ULK1 phosphorylation'. Together they form a unique fingerprint.

  • Cite this

    Dunlop, E. A., Seifan, S., Claessens, T., Behrends, C., Kamps, M. A. F., Rozycka, E., Kemp, A. J., Nookala, R. K., Blenis, J., Coull, B. J., Murray, J. T., van Steensel, M. A. M., Wilkinson, S., & Tee, A. R. (2014). FLCN, a novel autophagy component, interacts with GABARAP and is regulated by ULK1 phosphorylation. Autophagy, 10(10), 1749-1760. https://doi.org/10.4161/auto.29640