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Open AccessArticle

Permanent Photodynamic Activation of the Cholecystokinin 2 Receptor

Institute of Cell Biology, Beijing Normal University, Beijing 100875, China
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Author to whom correspondence should be addressed.
Biomolecules 2020, 10(2), 236; https://doi.org/10.3390/biom10020236 (registering DOI)
Received: 1 January 2020 / Revised: 30 January 2020 / Accepted: 1 February 2020 / Published: 4 February 2020
(This article belongs to the Section Chemical Biology)
The cholecystokinin 2 receptor (CCK2R) is expressed in the central nervous system and peripheral tissues, playing an important role in higher nervous and gastrointestinal functions, pain sensation, and cancer growth. CCK2R is reversibly activated by cholecystokinin or gastrin, but whether it can be activated permanently is not known. In this work, we found that CCK2R expressed ectopically in CHO-K1 cells was permanently activated in the dark by sulfonated aluminum phthalocyanine (SALPC/AlPcS4, 10–1000 nM), as monitored by Fura-2 fluorescent calcium imaging. Permanent CCK2R activation was also observed with AlPcS2, but not PcS4. CCK2R previously exposed to SALPC (3 and 10 nM) was sensitized by subsequent light irradiation (>580 nm, 31.5 mW·cm−2). After the genetically encoded protein photosensitizer mini singlet oxygen generator (miniSOG) was fused to the N-terminus of CCK2R and expressed in CHO-K1 cells, light irradiation (450 nm, 85 mW·cm−2) activated in-frame CCK2R (miniSOG-CCK2R), permanently triggering persistent calcium oscillations blocked by the CCK2R antagonist YM 022 (30 nM). From these data, it is concluded that SALPC is a long-lasting CCK2R agonist in the dark, and CCK2R is photogenetically activated permanently with miniSOG as photosensitizer. These properties of SALPC and CCK2R could be used to study CCK2R physiology and possibly for pain and cancer therapies. View Full-Text
Keywords: CCK2R; SALPC; miniSOG; calcium oscillations; photodynamic action CCK2R; SALPC; miniSOG; calcium oscillations; photodynamic action
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MDPI and ACS Style

Tang, W.Z.; Cui, Z.J. Permanent Photodynamic Activation of the Cholecystokinin 2 Receptor. Biomolecules 2020, 10, 236.

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