Rab8a is involved in membrane trafficking of Kir6.2 in the MIN6 insulinoma cell line

  • Keiichiro Uchida
  • Masatoshi Nomura
  • Tadashi Yamamoto
  • Yoshihiro Ogawa
  • Noriyoshi TeramotoEmail author
Ion channels, receptors and transporters
Part of the following topical collections:
  1. Ion channels, receptors and transporters


Although ATP-sensitive K+ (KATP) channels play an important role in the secretion of insulin by pancreatic beta cells, the mechanisms that regulate the intracellular transport of KATP channel subunit proteins (i.e., Kir6.2 and sulfonylurea receptor 1 (SUR1)) to the plasma membrane remain uncharacterized. We investigated the possibility that an interaction between KATP channel subunit proteins and Rab8a protein, a member of the RAS superfamily, may be involved in the membrane trafficking of KATP channels. Co-immunoprecipitation and immunostaining experiments using co-expression systems with fluorescent protein-tagged Kir6.2 were carried out to identify the coupling of KATP channels and Rab8a proteins in the insulin-secreting cell line, MIN6. Rab8a protein co-localized with Kir6.2 protein, a channel pore subunit (in a granular pattern), and with insulin. Knockdown of the Rab8a gene with RNA interference using small interfering RNA systems caused reductions in the amount of total KATP and plasma membrane surface KATP channels without decreasing the messenger RNA transcription of the KATP channel subunits. Rab8a gene knockdown also enhanced glucose-induced insulin secretion. These results suggest that Rab8a may be involved in membrane trafficking of KATP channels and the maintenance of normal insulin secretion in the MIN6 pancreatic beta cell line.


Channel trafficking Insulin Kir6.2 Pancreatic beta cell MIN6 Rab8a 



Aequorea coerulescens green fluorescent protein 1


Bovine serum albumin


Complementary DNA


Dulbecco’s modified Eagle’s medium


Endoplasmic reticulum


Fetal bovine serum


GTPase-activating protein


Glyceraldehyde 3-phosphate dehydrogenase


Guanine nucleotide exchange factor


Guanosine triphosphate


Horseradish peroxidase

KATP channels

ATP-sensitive K+ channels


Inwardly rectifying K+ channel 6 family


Krebs-Ringer HEPES


Messenger RNA


Phosphate-buffered saline


Polymerase chain reaction


Roswell Park Memorial Institute


Sodium dodecyl sulfate


Standard error of the mean


Small interfering RNA


Sulfonylurea receptor


Tris-buffered saline


0.2% Tween 20 in Tris-buffered saline



We thank our colleagues for their valuable suggestions and discussion.

Funding information

This work was supported in part by the Japanese Society for the Promotion of Science (JSPS) KAKENHI (M Nomura, grant number 17K09885; N Teramoto, grant number 17H02111) and Grants-in-Aid for Research Fellowship for Young Science Foundation (T Yamamoto, grant number 18K15030).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interest.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Keiichiro Uchida
    • 1
    • 2
  • Masatoshi Nomura
    • 3
  • Tadashi Yamamoto
    • 1
  • Yoshihiro Ogawa
    • 2
    • 4
  • Noriyoshi Teramoto
    • 1
    • 5
    Email author
  1. 1.Department of Pharmacology, Faculty of MedicineSaga UniversitySagaJapan
  2. 2.Department of Medicine and Bioregulatory Science, Graduate School of Medical ScienceKyushu UniversityFukuokaJapan
  3. 3.Division of Endocrinology and Metabolism, Department of Internal Medicine, School of MedicineKurume UniversityKurumeJapan
  4. 4.Department of Molecular and Cellular Metabolism, Graduate School of Medical and Dental SciencesTokyo Medical and Dental UniversityTokyoJapan
  5. 5.Laboratory of Biomedical Engineering, Graduate School of Biomedical EngineeringTohoku UniversitySendaiJapan

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