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  3. O2-Dependent Protein Internalization Underlies Astrocytic Sensing of Acute Hypoxia by Restricting Multimodal TRPA1 Channel Responses

O2-Dependent Protein Internalization Underlies Astrocytic Sensing of Acute Hypoxia by Restricting Multimodal TRPA1 Channel Responses

  • Curr Biol. 2020 Sep 7;30(17):3378-3396.e7. doi: 10.1016/j.cub.2020.06.047.
Makoto Uchiyama 1,  Akito Nakao 1,  Yuki Kurita 1,  Isato Fukushi 2,  Kotaro Takeda 3,  Tomohiro Numata 4,  Ha Nam Tran 5,  Seishiro Sawamura 1,  Maximilian Ebert 1,  Tatsuki Kurokawa 1,  Reiko Sakaguchi 6,  Alexander J Stokes 7,  Nobuaki Takahashi 1,  Yasumasa Okada 8,  Yasuo Mori 9
Affiliations

Affiliations

  • 1 Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
  • 2 Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Health Sciences, Uekusa Gakuen University, Chiba 264-0007, Japan.
  • 3 Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Rehabilitation, School of Healthcare, Fujita Health University, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
  • 4 Department of Physiology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
  • 5 Department of Technology and Ecology, Graduate School of Global Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
  • 6 Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan; World Premier International Research Initiative Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto 606-8501, Japan.
  • 7 Chaminade University, Honolulu, HI 96816, USA; Laboratory of Experimental Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA.
  • 8 Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan.
  • 9 Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan. Electronic address: [email protected].
PMID: 32679097 DOI: 10.1016/j.cub.2020.06.047
Abstract

Hypoxia sensors are essential for regulating local oxygen (O2) homeostasis within the body. This is especially pertinent within the CNS, which is particularly vulnerable to O2 deprivation due to high energetic demand. Here, we reveal hypoxia-monitoring function exerted by astrocytes through an O2-regulated protein trafficking mechanism within the CNS. Strikingly, cultured mouse astrocytes isolated from the parafacial respiratory group (pFRG) and retrotrapezoid nucleus (RTN) region are capable of rapidly responding to moderate hypoxia via the sensor cation channel transient receptor potential (TRP) A1 but, unlike multimodal sensory neurons, are inert to hyperoxia and other TRPA1 activators (carbon dioxide, electrophiles, and oxidants) in normoxia. Mechanistically, O2 suppresses TRPA1 channel activity by protein internalization via O2-dependent proline hydroxylation and subsequent ubiquitination by an E3 ubiquitin ligase, NEDD4-1 (neural precursor cell-expressed developmentally down-regulated protein 4). Hypoxia inhibits this process and instantly accumulates TRPA1 proteins at the plasma membrane, inducing TRPA1-mediated Ca2+ influx that triggers ATP release from pFRG/RTN astrocytes, potentiating respiratory center activity. Furthermore, astrocyte-specific Trpa1 disruption in a mouse brainstem-spinal cord preparation impedes the amplitude augmentation of the central autonomic respiratory output during hypoxia. Thus, reversible coupling of the TRPA1 channels with O2-dependent protein translocation allows astrocytes to act as acute hypoxia sensors in the medullary respiratory center.

Keywords

Ca(2+); O(2) sensor; TRP channels; astrocyte; channel trafficking; hypoxia; respiration; stress; ubiquitination.

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