https://scholar.dgist.ac.kr/handle/20.500.11750/305 2026-10-19T04:08:56Z https://scholar.dgist.ac.kr/handle/20.500.11750/60947 Title: Caenorhabditis elegans avoids epigallocatechin gallate (EGCG) through SRXA-7 G-protein coupled receptor Author(s): Cheon, YongJin; Hwang, Hyeonjeong; Kim, Kyuhyung Abstract: Flavonoids are plant-derived polyphenols that influence nematode behavior, yet their neuronal and molecular targets remain poorly understood. Here, we show that the free-living nematode Caenorhabditis elegans detects and avoids a green tea catechin epigallocatechin gallate (EGCG) via the SRXA-7 Gprotein coupled receptor (GPCR) in the ASH nociceptive neurons. EGCG and epicatechin gallate (ECG), both containing a galloyl group, trigger strong avoidance, unlike other green tea catechins lacking this moiety. EGCG avoidance behavior displays species-and strain-specific differences among Caenorhabditis species and wild C. elegans isolates. Moreover, it is dynamically modulated by prior experience and feeding state. The ASH chemosensory neurons are required for EGCG detection, with avoidance mediated through canonical GPCR signaling components including GRK-2, GPA-3, ODR-3, and TRPV channels OCR-2 and OSM-9. A targeted GPCR screen revealed that srxa-7 mutants exhibited specific defects in EGCG avoidance. EGCG-evoked calcium responses in ASH are reduced in srxa-7 mutants and restored by ASH-specific expression of srxa-7 cDNA. These findings indicate that SRXA-7 is a sensory receptor for galloylated polyphenols, uncovering the neuronal and molecular basis of adaptive aversive responses to dietary plant compounds in nematodes. [BMB Reports 2026; 59(8): 384-390] 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58901 Title: A practical guide to ordering C. elegans strains for biological research Author(s): Park, Yeon-Ji; Moon, Kyeong Min; Kim, Kyuhyung Abstract: Caenorhabditis elegans (C. elegans) is a widely used model organism in biological research, contributing to our understanding of fundamental processes in areas such as development, neurobiology, and aging. Accessing the appropriate C. elegans strains is crucial for conducting experiments and advancing scientific knowledge. This work provides a comprehensive overview of the process of ordering C. elegans. 2025-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58220 Title: Cryo-EM structures of mouse bestrophin 1 channel in closed and partially open conformations Author(s): Kim, Kwon-Woo; Lee, Euna; Ko, Ara; Hwang, Junmo; Park, Kunwoong; Lee, Byoung-Cheol; Kim, Ki Woo; Oh, Won-Jong; Kim, Kyuhyung; Lim, Hyun-Ho Abstract: Bestrophin 1 (BEST1) channels are calcium-activated Cl- channels involved in diverse physiological processes, including gliotransmitter release in astrocytes. Although human and chicken BEST1 orthologs have been extensively studied, the structural and functional properties of mouse BEST1 (mBEST1) remain poorly understood. In this study, we characterized the structure-function of mBEST1-BF, a C-terminally tagged variant, using whole-cell patch-clamp recordings, surface biotinylation assays, and single-particle cryo-electron microscopy. Cryo-electron microscopy structural analysis of mBEST1-BF revealed closed and partially open conformations. Comparative analysis with human and chicken BEST1 orthologs highlighted conserved calcium-binding and gating mechanisms, with distinct features in mBEST1, including a wider aperture sufficient to accommodate dehydrated Cl- ions and potential anion-binding sites near Val205 and Gln208 residues. The disordered C-terminal region of mBEST1 remains unresolved, suggesting it may require stabilizing factors for structural determination. Additionally, the autoinhibitory domain, which includes Ser354, likely plays a key role in regulating gating, with Ser354 potentially serving as a phosphorylation site that modulates channel activity. Our findings provide structural and functional insights into mBEST1 and suggest mechanisms underlying its unique gating and ion (c) 2025 The Author(s). Published by Elsevier Inc. on behalf of Korean Society for Molecular and Cellular Biology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 2025-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58140 Title: An evolutionarily conserved cation channel tunes the sensitivity of gustatory neurons to ephaptic inhibition in Drosophila Author(s): Lee, MinHyuk; Kim, Seon Yeong; Park, Taeim; Yoon, Sung-Eun; Kim, Young-Joon; Joo, Kyeung Min; Kwon, Jae Young; Kim, Kyuhyung; Kang, KyeongJin Abstract: In ephaptic coupling, physically adjacent neurons influence one another’s activity via the electric fields they generate. To date, the molecular mechanisms that mediate and modulate ephaptic coupling’s effects remain poorly understood. Here, we show that the hyperpolarization-activated cyclic nucleotide–gated (HCN) channel lateralizes the potentially mutual ephaptic inhibition between Drosophila gustatory receptor neurons (GRNs). While sweet-sensing GRNs (sGRNs) engage in ephaptic suppression of the adjacent bitter-sensing GRNs (bGRNs), HCN expression in sGRNs enables them to resist ephaptic suppression from the bGRNs. This one-sided ephaptic inhibition confers sweetness dominance, facilitating ingestion of bitter-laced sweets. The role of fly HCN in this process can be replaced by human HCN2. Furthermore, unlike the mechanism in olfaction, gustatory ephaptic inhibition is independent of sensillum potential changes, suggesting that the compartmentalized arrangement of neighboring GRNs is dispensable for gustatory ephaptic inhibition. These findings indicate a role for the gating of ephaptic coding to ensure the intake of the essential nutrient despite bitter contaminants present in the feeding niche of Drosophila, and propose that studies in Drosophila gustation could reveal ephaptic principles conserved across diverse animals. Copyright © 2025 the Author(s). 2024-12-31T15:00:00Z