Proteasomal degradation of the tumour suppressor FBW7 requires branched ubiquitylation by TRIP12

The tumour suppressor FBW7 is a substrate adaptor for the E3 ubiquitin ligase complex SKP1-CUL1-F-box (SCF), that targets several oncoproteins for proteasomal degradation. FBW7 is widely mutated and FBW7 protein levels are commonly downregulated in cancer. Here, using an shRNA library screen, we identify the HECT-domain E3 ubiquitin ligase TRIP12 as a negative regulator of FBW7 stability. We find that SCFFBW7-mediated ubiquitylation of FBW7 occurs preferentially on K404 and K412, but is not sufficient for its proteasomal degradation, and in addition requires TRIP12-mediated branched K11-linked ubiquitylation. TRIP12 inactivation causes FBW7 protein accumulation and increased proteasomal degradation of the SCFFBW7 substrate Myeloid Leukemia 1 (MCL1), and sensitizes cancer cells to anti-tubulin chemotherapy. Concomitant FBW7 inactivation rescues the effects of TRIP12 deficiency, confirming FBW7 as an essential mediator of TRIP12 function. This work reveals an unexpected complexity of FBW7 ubiquitylation, and highlights branched ubiquitylation as an important signalling mechanism regulating protein stability.

Biocatalysis, Carrier Proteins/metabolism, Drug Resistance, Neoplasm, F-Box-WD Repeat-Containing Protein 7/metabolism, HCT116 Cells, HEK293 Cells, Humans, Lysine/metabolism, Myeloid Cell Leukemia Sequence 1 Protein/metabolism, Proteasome Endopeptidase Complex/metabolism, Protein Binding, Protein Processing, Post-Translational, Protein Stability, Proteolysis, RNA, Small Interfering/metabolism, Substrate Specificity, Ubiquitin-Conjugating Enzymes/metabolism, Ubiquitin-Protein Ligases/metabolism, Ubiquitination

10.1038/s41467-021-22319-5

2041-1723

Khan, Omar M.

b0170e98-eb6b-44b9-b3b5-d9dd70b67850

Almagro, Jorge

9cba7dad-ab1f-423e-8ab6-d3ca4b3866f9

Nelson, Jessica K.

7dc3f0c8-5a67-4467-a332-efd560a0630b

Horswell, Stuart

825be868-2c8b-4dfe-a6ee-cfcf77cdf21b

Encheva, Vesela

3535cb24-bdaf-4534-b25a-464e0a215634

Keyan, Kripa S.

bc28a242-1c06-469b-b532-5d772c86eb56

Clurman, Bruce E.

304b7384-4cd9-4c3d-8946-9932a469da5b

Snijders, Ambrosius P.

e6cc15c4-9ca4-4eda-9431-0aaee95bf567

Behrens, Axel

562a632f-5241-42aa-b554-d3c593f9b7ce

6 April 2021

Khan, Omar M.

b0170e98-eb6b-44b9-b3b5-d9dd70b67850

Almagro, Jorge

9cba7dad-ab1f-423e-8ab6-d3ca4b3866f9

Nelson, Jessica K.

7dc3f0c8-5a67-4467-a332-efd560a0630b

Horswell, Stuart

825be868-2c8b-4dfe-a6ee-cfcf77cdf21b

Encheva, Vesela

3535cb24-bdaf-4534-b25a-464e0a215634

Keyan, Kripa S.

bc28a242-1c06-469b-b532-5d772c86eb56

Clurman, Bruce E.

304b7384-4cd9-4c3d-8946-9932a469da5b

Snijders, Ambrosius P.

e6cc15c4-9ca4-4eda-9431-0aaee95bf567

Behrens, Axel

562a632f-5241-42aa-b554-d3c593f9b7ce

Khan, Omar M., Almagro, Jorge, Nelson, Jessica K., Horswell, Stuart, Encheva, Vesela, Keyan, Kripa S., Clurman, Bruce E., Snijders, Ambrosius P. and Behrens, Axel (2021) Proteasomal degradation of the tumour suppressor FBW7 requires branched ubiquitylation by TRIP12. Nature Communications, 12 (1), [2043]. (doi:10.1038/s41467-021-22319-5).

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e-pub ahead of print date: 6 April 2021

Published date: 6 April 2021

Keywords: Biocatalysis, Carrier Proteins/metabolism, Drug Resistance, Neoplasm, F-Box-WD Repeat-Containing Protein 7/metabolism, HCT116 Cells, HEK293 Cells, Humans, Lysine/metabolism, Myeloid Cell Leukemia Sequence 1 Protein/metabolism, Proteasome Endopeptidase Complex/metabolism, Protein Binding, Protein Processing, Post-Translational, Protein Stability, Proteolysis, RNA, Small Interfering/metabolism, Substrate Specificity, Ubiquitin-Conjugating Enzymes/metabolism, Ubiquitin-Protein Ligases/metabolism, Ubiquitination