Regulation of the Axillary Osmidrosis-Associated ABCC11 Protein Stability by N-Linked Glycosylation: Effect of Glucose Condition

PLoS One. 2016 Jun 9;11(6):e0157172. doi: 10.1371/journal.pone.0157172. eCollection 2016.

Abstract

ATP-binding cassette C11 (ABCC11) is a plasma membrane protein involved in the transport of a variety of lipophilic anions. ABCC11 wild-type is responsible for the high-secretion phenotypes in human apocrine glands, such as that of wet-type ear wax, and the risk of axillary osmidrosis. We have previously reported that mature ABCC11 is a glycoprotein containing two N-linked glycans at Asn838 and Asn844. However, little is known about the role of N-linked glycosylation in the regulation of ABCC11 protein. In the current study, we investigated the effects of N-linked glycosylation on the protein level and localization of ABCC11 using polarized Madin-Darby canine kidney II cells. When the N-linked glycosylation in ABCC11-expressing cells was chemically inhibited by tunicamycin treatment, the maturation of ABCC11 was suppressed and its protein level was significantly decreased. Immunoblotting analyses demonstrated that the protein level of the N-linked glycosylation-deficient mutant (N838Q and N844Q: Q838/844) was about half of the ABCC11 wild-type level. Further biochemical studies with the Q838/844 mutant showed that this glycosylation-deficient ABCC11 was degraded faster than wild-type probably due to the enhancement of the MG132-sensitive protein degradation pathway. Moreover, the incubation of ABCC11 wild-type-expressing cells in a low-glucose condition decreased mature, glycosylated ABCC11, compared with the high-glucose condition. On the other hand, the protein level of the Q838/844 mutant was not affected by glucose condition. These results suggest that N-linked glycosylation is important for the protein stability of ABCC11, and physiological alteration in glucose may affect the ABCC11 protein level and ABCC11-related phenotypes in humans, such as axillary osmidrosis.

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Amino Acid Substitution
  • Animals
  • Dogs
  • Glucose / metabolism*
  • Glycosylation
  • HEK293 Cells
  • Humans
  • Madin Darby Canine Kidney Cells
  • Mutation, Missense
  • Protein Stability
  • Proteolysis*

Substances

  • ABCC11 protein, human
  • ATP-Binding Cassette Transporters
  • Glucose

Grants and funding

This study was supported by Japan Society for the Promotion of Science (JSPS, https://www.jsps.go.jp/) KAKENHI grant number 12J03163 and 15H05610 to YT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The NGO Personalized Medicine & Healthcare (founder and president: Dr. Toshihisa Ishikawa) did not take any role of fund provider in the present study at all. In addition, this non-governmental organization did not play a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Dr. Ishikawa only contributed to the writing of the manuscript as a critical reviewer and scientific adviser. In other words, Dr. Ishikawa contributed scientifically, but not financially, to this research.