Browsing by Author "Ko, Mee Jung"

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    A critical evaluation of TRPA1-mediated locomotor behavior in zebrafish as a screening tool for novel anti-nociceptive drug discovery
    (Springer Nature, 2019-02-20) Ko, Mee Jung; Ganzen, Logan C.; Coskun, Emre; Mukadam, Arbaaz A.; Leung, Yuk Fai; van Rijn, Richard M.; Biochemistry and Molecular Biology, School of Medicine
    Current medications inadequately treat the symptoms of chronic pain experienced by over 50 million people in the United States, and may come with substantial adverse effects signifying the need to find novel treatments. One novel therapeutic target is the Transient Receptor Potential A1 channel (TRPA1), an ion channel that mediates nociception through calcium influx of sensory neurons. Drug discovery still relies heavily on animal models, including zebrafish, a species in which TRPA1 activation produces hyperlocomotion. Here, we investigated if this hyperlocomotion follows zebrafish TRPA1 pharmacology and evaluated the strengths and limitations of using TRPA1-mediated hyperlocomotion as potential preclinical screening tool for drug discovery. To support face validity of the model, we pharmacologically characterized mouse and zebrafish TRPA1 in transfected HEK293 cells using calcium assays as well as in vivo. TRPA1 agonists and antagonists respectively activated or blocked TRPA1 activity in HEK293 cells, mice, and zebrafish in a dose-dependent manner. However, our results revealed complexities including partial agonist activity of TRPA1 antagonists, bidirectional locomotor activity, receptor desensitization, and off-target effects. We propose that TRPA1-mediated hyperlocomotion in zebrafish larvae has the potential to be used as in vivo screening tool for novel anti-nociceptive drugs but requires careful evaluation of the TRPA1 pharmacology.
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    Drug screening with zebrafish visual behavior identifies carvedilol as a potential treatment for an autosomal dominant form of retinitis pigmentosa
    (Springer Nature, 2021-06-01) Ganzen, Logan; Ko, Mee Jung; Zhang, Mengrui; Xie, Rui; Chen, Yongkai; Zhang, Liyun; James, Rebecca; Mumm, Jeff; van Rijn, Richard M.; Zhong, Wenxuan; Pang, Chi Pui; Zhang, Mingzhi; Tsujikawa, Motokazu; Leung, Yuk Fai; Biochemistry and Molecular Biology, School of Medicine
    Retinitis Pigmentosa (RP) is a mostly incurable inherited retinal degeneration affecting approximately 1 in 4000 individuals globally. The goal of this work was to identify drugs that can help patients suffering from the disease. To accomplish this, we screened drugs on a zebrafish autosomal dominant RP model. This model expresses a truncated human rhodopsin transgene (Q344X) causing significant rod degeneration by 7 days post-fertilization (dpf). Consequently, the larvae displayed a deficit in visual motor response (VMR) under scotopic condition. The diminished VMR was leveraged to screen an ENZO SCREEN-WELL REDOX library since oxidative stress is postulated to play a role in RP progression. Our screening identified a beta-blocker, carvedilol, that ameliorated the deficient VMR of the RP larvae and increased their rod number. Carvedilol may directly on rods as it affected the adrenergic pathway in the photoreceptor-like human Y79 cell line. Since carvedilol is an FDA-approved drug, our findings suggest that carvedilol can potentially be repurposed to treat autosomal dominant RP patients.