Manganese-induced Turnover of TMEM165

Biochem J. 2017 Apr 19;474(9):1481-1493. doi: 10.1042/BCJ20160910.

Abstract

TMEM165 deficiencies lead to one of the congenital disorders of glycosylation (CDG), a group of inherited diseases where the glycosylation process is altered. We recently demonstrated that the Golgi glycosylation defect due to TMEM165 deficiency resulted from a Golgi manganese homeostasis defect and that Mn2+ supplementation was sufficient to rescue normal glycosylation. In the present paper, we highlight TMEM165 as a novel Golgi protein sensitive to manganese. When cells were exposed to high Mn2+ concentrations, TMEM165 was degraded in lysosomes. Remarkably, while the variant R126H was sensitive upon manganese exposure, the variant E108G, recently identified in a novel TMEM165-CDG patient, was found to be insensitive. We also showed that the E108G mutation did not abolish the function of TMEM165 in Golgi glycosylation. Altogether, the present study identified the Golgi protein TMEM165 as a novel Mn2+-sensitive protein in mammalian cells and pointed to the crucial importance of the glutamic acid (E108) in the cytosolic ELGDK motif in Mn2+-induced degradation of TMEM165.

Keywords: Golgi apparatus; TMEM165; congenital disorders of glycosylation; glycosylation; manganese.

MeSH terms

  • Amino Acid Motifs / genetics
  • Amino Acid Sequence
  • Blotting, Western
  • Calcium-Transporting ATPases / genetics
  • Calcium-Transporting ATPases / metabolism
  • Dose-Response Relationship, Drug
  • Gene Knockdown Techniques
  • Glutamates / genetics
  • Glutamates / metabolism
  • Glycosylation / drug effects
  • Golgi Apparatus / drug effects*
  • Golgi Apparatus / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Lysosomes / drug effects*
  • Lysosomes / metabolism
  • Manganese / pharmacology*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Microscopy, Confocal
  • Mutation
  • Proteolysis / drug effects

Substances

  • Glutamates
  • Membrane Proteins
  • TMEM165 protein, human
  • Manganese
  • ATP2C1 protein, human
  • Calcium-Transporting ATPases