2. Academic Validation
  3. ANKRD9 is associated with tumor suppression as a substrate receptor subunit of ubiquitin ligase

ANKRD9 is associated with tumor suppression as a substrate receptor subunit of ubiquitin ligase

  • Biochim Biophys Acta Mol Basis Dis. 2018 Oct;1864(10):3145-3153. doi: 10.1016/j.bbadis.2018.07.001.
Yejin Lee 1,  Byungho Lim 2,  Seon Woo Lee 3,  Woo Rin Lee 4,  Yong-In Kim 5,  Minhyeok Kim 6,  Hyoungseok Ju 7,  Mi Young Kim 8,  Suk-Jo Kang 9,  Ji-Joon Song 10,  J Eugene Lee 11,  Changwon Kang 12
Affiliations

Affiliations

  • 1 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea; Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea. Electronic address: [email protected].
  • 2 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 3 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 4 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 5 Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea. Electronic address: [email protected].
  • 6 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 7 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 8 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea; Cancer Metastasis Control Center, KAIST Institute for BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 9 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 10 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea; Cancer Metastasis Control Center, KAIST Institute for BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
  • 11 Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea. Electronic address: [email protected].
  • 12 Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea. Electronic address: [email protected].
PMID: 30293565 DOI: 10.1016/j.bbadis.2018.07.001
Abstract

Background: Human ANKRD9 (ankyrin repeat domain 9) expression is altered in some cancers.

Methods: We tested genetic association of ANKRD9 with gastric Cancer susceptibility and examined functional association of ANKRD9 with altered proliferation of MKN45 gastric Cancer cells. We then identified ANKRD9-binding partners in HEK 293 embryonic kidney cells using quantitative proteomics, western blotting and complex reconstitution assays. We finally demonstrated ANKRD9's role of recognizing substrates for ubiquitination using in vitro ubiquitylation assay.

Results: ANKRD9 is associated with Cancer susceptibility in a comparison of single-nucleotide polymorphisms between 1092 gastric Cancer patients and 1206 healthy controls. ANKRD9 depletion accelerates tumor progression by increasing cellular proliferation, piling up, and anchorage-independent growth of MKN45 cells. We discovered that ANKRD9 is a ubiquitin ligase substrate receptor subunit and has an anti-proliferative activity. ANKRD9 associates with CUL5 (not CUL2), ELOB, ELOC, and presumably RNF7 subunits, which together assemble into a cullin-RING superfamily E3 ligase complex. ANKRD9 belongs to the ASB family of proteins, which are characterized by the presence of ankyrin repeats and a SOCS box. In addition to its interactions with the other E3 ligase subunits, ANKRD9 interacts with two isoforms of inosine monophosphate dehydrogenase (IMPDH). These IMPDH isoforms are cognate substrates of the ANKRD9-containing E3 Enzyme, which ubiquitinates them for proteasomal degradation. Their ubiquitination and turnover require the presence of ANKRD9.

Conclusion: ANKRD9, a previously unidentified E3 substrate receptor subunit, functions in tumor suppression by recognizing the oncoprotein IMPDH isoforms for E3 ubiquitination and proteasomal degradation.

Keywords

ASB family; Cullin-RING superfamily; Gastric cancer susceptibility; SOCS box protein; Ubiquitylation.

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