A high-coverage shRNA screen identifies TMEM129 as an E3 ligase involved in ER-associated protein degradation

Nat Commun. 2014 May 8;5:3832. doi: 10.1038/ncomms4832.

Abstract

Misfolded ER proteins are retrotranslocated into the cytosol for degradation via the ubiquitin-proteasome system. The human cytomegalovirus protein US11 exploits this ER-associated protein degradation (ERAD) pathway to downregulate HLA class I molecules in virus-infected cells, thereby evading elimination by cytotoxic T-lymphocytes. US11-mediated degradation of HLA class I has been instrumental in the identification of key components of mammalian ERAD, including Derlin-1, p97, VIMP and SEL1L. Despite this, the process governing retrotranslocation of the substrate is still poorly understood. Here using a high-coverage genome-wide shRNA library, we identify the uncharacterized protein TMEM129 and the ubiquitin-conjugating E2 enzyme UBE2J2 to be essential for US11-mediated HLA class I downregulation. TMEM129 is an unconventional C4C4-type RING finger E3 ubiquitin ligase that resides within a complex containing various other ERAD components, including Derlin-1, Derlin-2, VIMP and p97, indicating that TMEM129 is an integral part of the ER-resident dislocation complex mediating US11-induced HLA class I degradation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Cell Line, Tumor
  • Clustered Regularly Interspaced Short Palindromic Repeats / genetics
  • Cytomegalovirus / genetics
  • Cytomegalovirus Infections
  • Down-Regulation
  • Endoplasmic Reticulum / pathology
  • Endoplasmic Reticulum-Associated Degradation
  • HEK293 Cells
  • Histocompatibility Antigens Class I / biosynthesis*
  • Humans
  • Membrane Proteins / genetics
  • Nuclear Proteins / genetics
  • Protein Folding
  • Proteins / genetics
  • RNA Interference*
  • RNA, Small Interfering
  • RNA-Binding Proteins / genetics*
  • Selenoproteins / genetics
  • U937 Cells
  • Ubiquitin-Conjugating Enzymes / genetics*
  • Ubiquitin-Protein Ligases / genetics*
  • Viral Proteins / genetics*

Substances

  • DERL1 protein, human
  • Histocompatibility Antigens Class I
  • Membrane Proteins
  • Nuclear Proteins
  • Proteins
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • SEL1L protein, human
  • SELENOS protein, human
  • Selenoproteins
  • US11 protein, herpesvirus
  • Viral Proteins
  • UBE2J2 protein, human
  • Ubiquitin-Conjugating Enzymes
  • TMEM129 protein, human
  • Ubiquitin-Protein Ligases
  • Adenosine Triphosphatases
  • p97 ATPase