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Liu HW, Gong LN, Lai K, Yu XF, Liu ZQ, Li MX, Yin XL, Liang M, Shi HS, Jiang LH, Yang W, Shi HB, Wang LY, Yin SK. Bilirubin gates the TRPM2 channel as a direct agonist to exacerbate ischemic brain damage. Neuron 2023; 111:1609-1625.e6. [PMID: 36921602 DOI: 10.1016/j.neuron.2023.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 10/18/2022] [Accepted: 02/13/2023] [Indexed: 03/16/2023]
Abstract
Stroke prognosis is negatively associated with an elevation of serum bilirubin, but how bilirubin worsens outcomes remains mysterious. We report that post-, but not pre-, stroke bilirubin levels among inpatients scale with infarct volume. In mouse models, bilirubin increases neuronal excitability and ischemic infarct, whereas ischemic insults induce the release of endogenous bilirubin, all of which are attenuated by knockout of the TRPM2 channel or its antagonist A23. Independent of canonical TRPM2 intracellular agonists, bilirubin and its metabolic derivatives gate the channel opening, whereas A23 antagonizes it by binding to the same cavity. Knocking in a loss of binding point mutation for bilirubin, TRPM2-D1066A, effectively antagonizes ischemic neurotoxicity in mice. These findings suggest a vicious cycle of stroke injury in which initial ischemic insults trigger the release of endogenous bilirubin from injured cells, which potentially acts as a volume neurotransmitter to activate TRPM2 channels, aggravating Ca2+-dependent brain injury.
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Affiliation(s)
- Han-Wei Liu
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Li-Na Gong
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Ke Lai
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China; Program in Neuroscience and Mental Health, SickKids Research Institute, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Xia-Fei Yu
- Department of Biophysics, Institute of Neuroscience, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhen-Qi Liu
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China; Program in Neuroscience and Mental Health, SickKids Research Institute, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ming-Xian Li
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Xin-Lu Yin
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China; Department of Head & Neck Surgery, Renji Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Min Liang
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China; Department of Otorhinolaryngology Head & Neck Surgery, Xinhua Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Hao-Song Shi
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Lin-Hua Jiang
- Department of Physiology and Pathophysiology, School of Basic Sciences, Xinxiang Medical University, Xinxiang, Henan Province 453003, China; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Wei Yang
- Department of Biophysics, Institute of Neuroscience, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Hai-Bo Shi
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China.
| | - Lu-Yang Wang
- Program in Neuroscience and Mental Health, SickKids Research Institute, Toronto, ON M5G 1X8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Shan-Kai Yin
- Department of Otorhinolaryngology Head & Neck Surgery, Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China.
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Compernolle F, Van Hees GP, Blanckaert N, Heirwegh KP. Glucuronic acid conjugates of bilirubin-IXalpha in normal bile compared with post-obstructive bile. Transformation of the 1-O-acylglucuronide into 2-, 3-, and 4-O-acylglucuronides. Biochem J 1978; 171:185-201. [PMID: 646816 PMCID: PMC1184148 DOI: 10.1042/bj1710185] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Structures have been determined for bilirubin-IXalpha conjugates in freshly collected bile of normal rats, dogs and man and in post-obstructive bile of man and rats. The originally secreted conjugate has been characterized as azopigment (I), i.e. a 1-O-acyl-beta-d-glucopyranuronic acid glycoside. Conversion of the acetylated methyl ester of azopigment (I) into methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-beta-d-glucopyranuronate (V) indicates the pyranose ring structure for the carbohydrate and a C-1 attachment for the bilirubin-IXalpha acyl group. Alternative procedures for deconjugation of azopigment (I) and its derivatives are also described. In post-obstructive bile, the 1-O-acylglucuronide is converted into 2-, 3- and 4-O-acylglucuronides via sequential intramolecular migrations of the bilirubin acyl group. The following approach was utilized. (1) The tetrapyrrole conjugates were cleaved to dipyrrolic aniline and ethyl anthranilate azopigments, and the azopigments were separated as the acids or methyl esters. (2) The isomeric methyl esters were characterized by mass spectral analysis of the acetates and silyl ethers. (3) The free glycosidic function was demonstrated by 1-oxime and 1-methoxime derivative formation. (4) The position of the dipyrrolic O-acyl group was determined for the methyl esters by protecting the free hydroxyl groups of the glucuronic acid moieties as the acetals formed with ethyl vinyl ether and by further conversion of the carbohydrates into partially methylated alditol acetates. These were analysed by using g.l.c.-mass spectrometry. The relevance of the present results with regard to previous reports on disaccharidic conjugates is discussed. Details of procedures for the formation of chemical derivatives for g.l.c. and mass spectrometry have been deposited as Supplementary Publication SUP 50081 (15 pages) at the British Library Lending Division, Boston Spa, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978), 169, 5.
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Compernolle F, Blanckaert N, Heirwegh KP. Mass spectral study of derivatives of the four bilirubin-IX isomers. BIOMEDICAL MASS SPECTROMETRY 1976; 3:155-60. [PMID: 963272 DOI: 10.1002/bms.1200030403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The beta, gamma and delta isomers of bilirubin-IX show a decreased stability as compared with the IXalpha isomer; characteristic mass spectra are obtained only for the tetrakis-(trimethylsilyl) derivatives of the IXalpha and IXgamma isomers. Hydrogenation of the vinyl substituents increases the thermal stability of the bilirubins and gives rise to a characteristic mass spectrum for the tetrakis-(trimethylsilyl) derivative of meso-bilirubin-IXdelta. The ethyl anthranilate azopigments derived from the four bilirubins yield characteristic mass spectra, except for the two unstable divinyl substituted azodipyrroles (mol. wt. 416), derived from bilirubin-IXbeta and IXdelta. The corresponding mol. wt. 420 azopigments derived from the hydrogenated bilirubins are thermally stable. Elucidation of mass spectral fragmentation pathways is facilitated by the varying positions of the substituents and by deuterium labelling, and permits the assignment of structures to the various isomeric azodipyrroles.
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Blanckaert N, Heirwegh KP, Compernolle F. Synthesis and separation by thin-layer chromatography of bilirubin-IX isomers. Their identification as tetrapyrroles and dipyrrolic ethyl anthranilate azo derivatives. Biochem J 1976; 155:405-17. [PMID: 938489 PMCID: PMC1172847 DOI: 10.1042/bj1550405] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Procedures for the synthesis, separation and determination of structure of the bilirubin-IX isomers are described. 1. The four biliverdin-IX isomers were prepared by oxidative cleavage of haemin and were separated as their dimethyl esters. The individual esters were reduced with NaBH4, and the bilirubin esters obtained were subjected to alkaline hydrolysis yielding the corresponding bilirubin-IX isomers. 2. The bilirubin-IX isomers were structurally characterized (a) at the tetrapyrrolic stage by mass spectrometry of their trimethylsilyl derivatives and (b) by formation and structural analysis of their dipyrrolic ethyl anthranilate azo derivatives. 3. The absorption spectrum of bilirubin-IX alpha differed strikingly from the spectra of the other isomers. The presence of a pronounced shoulder around 453 nm in the spectrum of bilirubin-IXbeta allows easy differentiation from bilirubin-IXdelta. Methylation of the carboxyl groups largely eliminates the spectral differences between the IXalpha- and non-alpha isomers. 4. The bilirubin-IX isomers are conveniently separated by t.l.c. Detection and unequivocal identification is possible on a micro-scale by (a) t.l.c. with respect to reference compounds and (b) subsequent formation and t.l.c. of the more stable ethyl anthranilate azopigments. 5. Pronounced differences in polarity, i.e. solvent distribution, between the bilirubin-IX isomers indicate that a re-evaluation of conclusions reached previously with regard to the presence in, or absence from, biological fluids of some isomers and their relative amounts is needed.
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