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GPHR is a novel anion channel critical for acidification and functions of the Golgi apparatus

Nature Cell Biology volume 10, pages 11351145 (2008) | Download Citation

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Abstract

The organelles within secretory and endocytotic pathways in mammalian cells have acidified lumens, and regulation of their acidic pH is critical for the trafficking, processing and glycosylation of cargo proteins and lipids, as well as the morphological integrity of the organelles. How organelle lumen acidification is regulated, and how luminal pH elevation disturbs these fundamental cellular processes, is largely unknown. Here, we describe a novel molecule involved in Golgi acidification. First, mutant cells defective in Golgi acidification were established that exhibited delayed protein transport, impaired glycosylation and Golgi disorganization. Using expression cloning, a novel Golgi-resident multi-transmembrane protein, named Golgi pH regulator (GPHR), was identified as being responsible for the mutant cells. After reconstitution in planar lipid bilayers, GPHR exhibited a voltage-dependent anion-channel activity that may function in counterion conductance. Thus, GPHR modulates Golgi functions through regulation of acidification.

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Acknowledgements

We thank F. Mori and K. Kinoshita for excellent technical assistance, and K. Nakamura for help with the cell sorting. We also thank T. Yoshimori, S. Kimura and H. Oomori for allowing us to use confocal and electron microscopes and for technical direction, and H. Hibino, H. Takeshima and T. Yamazaki for helpful discussions. This work was supported by grants from the Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency (Y.M.), the Core Research for Evolutional Science and Technology, Japan Science and Technology Agency (T.K.) and the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Author information

Author notes

    • Masato Koike
    •  & Yasuo Uchiyama

    Current address: Department of Cell Biology and Neuroscience, Juntendo University School of Medicine, Tokyo 113–8421, Japan.

Affiliations

  1. Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565–0871, Japan.

    • Yusuke Maeda
    •  & Taroh Kinoshita
  2. WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565–0871, Japan.

    • Yusuke Maeda
    •  & Taroh Kinoshita
  3. PRESTO Japan Science and Technology Agency, Saitama 332–0012, Japan.

    • Yusuke Maeda
  4. Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565–0871, Japan.

    • Toru Ide
  5. Molecular-Informational Life Science Research Group, RIKEN, Wako 351–0198, Japan.

    • Toru Ide
  6. Department of Cell Biology and Neurosciences, Graduate School of Medicine, Osaka University, Suita, Osaka 565–0871, Japan.

    • Masato Koike
    •  & Yasuo Uchiyama
  7. CREST, Japan Science and Technology Agency, Saitama 332–0012, Japan.

    • Taroh Kinoshita

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Contributions

T.I. performed the planar lipid-bilayer analyses. M.K. and Y.U. performed the electron microscopy analyses. Y.M. performed the other experiments. T.K. and Y.M. contributed to the planning of experiments and wrote the manuscript. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yusuke Maeda.

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    Supplementary Information

    Supplementary Figures S1, S2, S3, S4, S5, S6, S7, S8, Supplementary Materials and Methods

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DOI

https://doi.org/10.1038/ncb1773