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Li Q, Chen G, Yan J. Transmembrane determinants of voltage-gating differences between BK (Slo1) and Slo3 channels. Biophys J 2024; 123:2154-2166. [PMID: 38637987 PMCID: PMC11309983 DOI: 10.1016/j.bpj.2024.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/01/2024] [Accepted: 04/15/2024] [Indexed: 04/20/2024] Open
Abstract
Voltage-gated potassium channels are critical in modulating cellular excitability, with Slo (slowpoke) channels forming a unique family characterized by their large conductance and dual regulation by electrical signals and intracellular messengers. Despite their structural and evolutionary similarities, Slo1 and Slo3 channels exhibit significant differences in their voltage-gating properties. This study investigates the molecular determinants that differentiate the voltage-gating properties of human Slo1 and mouse Slo3 channels. Utilizing Slo1/Slo3 chimeras, we pinpointed the selectivity filter region as a key factor in the Slo3 channel's reduced conductance at negative voltages. The S6 transmembrane (TM) segment was identified as pivotal for the Slo3 channel's biphasic deactivation kinetics at these voltages. Additionally, the S4 and S6 TM segments were found to be responsible for the gradual slope in the Slo3 channel's conductance-voltage relationship, while multiple TM regions appear to be involved in the Slo3 channel's requirement of strong depolarization for activation. Mutations in the Slo1's S5 and S6 TM segments revealed three residues (I233, L302, and M304) that likely play a crucial role in the allosteric coupling between the voltage sensors and the pore gate.
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Affiliation(s)
- Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas.
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2
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Yang H, Liu Q, Liu H, Kang X, Tian H, Kang Y, Li L, Yang X, Ren P, Kuang X, Wang X, Guo L, Tong M, Ma J, Fan W. Berberine alleviates concanavalin A-induced autoimmune hepatitis in mice by modulating the gut microbiota. Hepatol Commun 2024; 8:e0381. [PMID: 38466881 DOI: 10.1097/hc9.0000000000000381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 12/14/2023] [Indexed: 03/13/2024] Open
Abstract
BACKGROUND Autoimmune hepatitis (AIH) is an immune-mediated liver disease of unknown etiology accompanied by intestinal dysbiosis and a damaged intestinal barrier. Berberine (BBR) is a traditional antibacterial medicine that has a variety of pharmacological properties. It has been reported that BBR alleviates AIH, but relevant mechanisms remain to be fully explored. METHODS BBR was orally administered at doses of 100 mg⋅kg-1⋅d-1 for 7 days to mice before concanavalin A-induced AIH model establishment. Histopathological, immunohistochemical, immunofluorescence, western blotting, ELISA, 16S rRNA analysis, flow cytometry, real-time quantitative PCR, and fecal microbiota transplantation studies were performed to ascertain BBR effects and mechanisms in AIH mice. RESULTS We found that liver necrosis and apoptosis were decreased upon BBR administration; the levels of serum transaminase, serum lipopolysaccharide, liver proinflammatory factors TNF-α, interferon-γ, IL-1β, and IL-17A, and the proportion of Th17 cells in spleen cells were all reduced, while the anti-inflammatory factor IL-10 and regulatory T cell proportions were increased. Moreover, BBR treatment increased beneficial and reduced harmful bacteria in the gut. BBR also strengthened ileal barrier function by increasing the expression of the tight junction proteins zonula occludens-1 and occludin, thereby blocking lipopolysaccharide translocation, preventing lipopolysaccharide/toll-like receptor 4 (TLR4)/ NF-κB pathway activation, and inhibiting inflammatory factor production in the liver. Fecal microbiota transplantation from BBR to model mice also showed that BBR potentially alleviated AIH by altering the gut microbiota. CONCLUSIONS BBR alleviated concanavalin A-induced AIH by modulating the gut microbiota and related immune regulation. These results shed more light on potential BBR therapeutic strategies for AIH.
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Affiliation(s)
- Hao Yang
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Qingqing Liu
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Haixia Liu
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Xing Kang
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Haixia Tian
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Yongbo Kang
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
| | - Lin Li
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
| | - Xiaodan Yang
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Peng Ren
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Xiaoyu Kuang
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
| | - Xiaohui Wang
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
- Laboratory of Morphology, Shanxi Medical University, Jinzhong 030619, China
| | - Linzhi Guo
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
- Laboratory of Morphology, Shanxi Medical University, Jinzhong 030619, China
| | - Mingwei Tong
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
| | - Jieqiong Ma
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
| | - Weiping Fan
- Department of Microbiology and Immunology, Shanxi Medical University, Jinzhong, China
- Key Laboratory of Cellular Physiology (Shanxi Medical University), Ministry of Education, and Shanxi Key Laboratory of Cellular Physiology, Taiyuan, China
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Jia J, Zheng W, Tang S, Song S, Ai C. Scytosiphon lomentaria fucoidan ameliorates DSS-induced colitis in dietary fiber-deficient mice via modulating the gut microbiota and inhibiting the TLR4/NF-κB/MLCK pathway. Int J Biol Macromol 2023; 253:127337. [PMID: 37820918 DOI: 10.1016/j.ijbiomac.2023.127337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/28/2023] [Accepted: 10/08/2023] [Indexed: 10/13/2023]
Abstract
The prevalence of ulcerative colitis (UC) poses a serious threat to human health. This study showed that fiber-deficient diet (FD) increased the susceptibility of mice to low dosage of DSS-induced UC, and a UC model was established by feeding mice with DSS and FD to evaluate the effect of Scytosiphon lomentaria fucoidan (SLF) on UC. SLF ameliorated the symptoms of UC, as evidenced by increases in colon length, goblet cells and glycoprotein and reduction in inflammatory cell infiltration and intestinal epithelial injury. SLF alleviated oxidative stress and inhibited colonic inflammation by reducing the levels of lipopolysaccharides and pro-inflammatory cytokines and suppressing the activation of nuclear factor kappa B pathway. SLF protected tight junction integrity by reducing the level of myosin light chain kinase and increasing the levels of claudin, zonula occludens-1 and occludin. SLF improved serum metabolites profile and affected multiple metabolic pathways that are crucial to human health, e.g. butanoate metabolism. The underlying mechanism can be associated with modulation of the gut microbiota and metabolites, including increases in short chain fatty acids and reduction in Proteobacteria, Bacteroides and Romboutsia. It suggests that SLF could be developed as a prebiotic polysaccharide to benefit human health by improving intestinal microecology.
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Affiliation(s)
- Jinhui Jia
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034, PR China
| | - Weiyun Zheng
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034, PR China
| | - Shuangru Tang
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034, PR China
| | - Shuang Song
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034, PR China; National & Local Joint Engineering Laboratory for Marine Bioactive Polysaccharide Development and Application, Dalian Polytechnic University, Dalian 116034, PR China
| | - Chunqing Ai
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian 116034, PR China; National & Local Joint Engineering Laboratory for Marine Bioactive Polysaccharide Development and Application, Dalian Polytechnic University, Dalian 116034, PR China.
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Yamanouchi D, Kasuya G, Nakajo K, Kise Y, Nureki O. Dual allosteric modulation of voltage and calcium sensitivities of the Slo1-LRRC channel complex. Mol Cell 2023; 83:4555-4569.e4. [PMID: 38035882 DOI: 10.1016/j.molcel.2023.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 09/15/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Modulation of large conductance intracellular ligand-activated potassium (BK) channel family (Slo1-3) by auxiliary subunits allows diverse physiological functions in excitable and non-excitable cells. Cryoelectron microscopy (cryo-EM) structures of voltage-gated potassium (Kv) channel complexes have provided insights into how voltage sensitivity is modulated by auxiliary subunits. However, the modulation mechanisms of BK channels, particularly as ligand-activated ion channels, remain unknown. Slo1 is a Ca2+-activated and voltage-gated BK channel and is expressed in neurons, muscle cells, and epithelial cells. Using cryo-EM and electrophysiology, we show that the LRRC26-γ1 subunit modulates not only voltage but also Ca2+ sensitivity of Homo sapiens Slo1. LRRC26 stabilizes the active conformation of voltage-senor domains of Slo1 by an extracellularly S4-locking mechanism. Furthermore, it also stabilizes the active conformation of Ca2+-sensor domains of Slo1 intracellularly, which is functionally equivalent to intracellular Ca2+ in the activation of Slo1. Such a dual allosteric modulatory mechanism may be general in regulating the intracellular ligand-activated BK channel complexes.
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Affiliation(s)
- Daichi Yamanouchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Go Kasuya
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.
| | - Koichi Nakajo
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan
| | - Yoshiaki Kise
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Tan D, Lu M, Cai Y, Qi W, Wu F, Bao H, Qv M, He Q, Xu Y, Wang X, Shen T, Luo J, He Y, Wu J, Tang L, Barkat MQ, Xu C, Wu X. SUMOylation of Rho-associated protein kinase 2 induces goblet cell metaplasia in allergic airways. Nat Commun 2023; 14:3887. [PMID: 37393345 PMCID: PMC10314948 DOI: 10.1038/s41467-023-39600-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 06/21/2023] [Indexed: 07/03/2023] Open
Abstract
Allergic asthma is characterized by goblet cell metaplasia and subsequent mucus hypersecretion that contribute to the morbidity and mortality of this disease. Here, we explore the potential role and underlying mechanism of protein SUMOylation-mediated goblet cell metaplasia. The components of SUMOylaion machinery are specifically expressed in healthy human bronchial epithelia and robustly upregulated in bronchial epithelia of patients or mouse models with allergic asthma. Intratracheal suppression of SUMOylation by 2-D08 robustly attenuates not only allergen-induced airway inflammation, goblet cell metaplasia, and hyperreactivity, but IL-13-induced goblet cell metaplasia. Phosphoproteomics and biochemical analyses reveal SUMOylation on K1007 activates ROCK2, a master regulator of goblet cell metaplasia, by facilitating its binding to and activation by RhoA, and an E3 ligase PIAS1 is responsible for SUMOylation on K1007. As a result, knockdown of PIAS1 in bronchial epithelia inactivates ROCK2 to attenuate IL-13-induced goblet cell metaplasia, and bronchial epithelial knock-in of ROCK2(K1007R) consistently inactivates ROCK2 to alleviate not only allergen-induced airway inflammation, goblet cell metaplasia, and hyperreactivity, but IL-13-induced goblet cell metaplasia. Together, SUMOylation-mediated ROCK2 activation is an integral component of Rho/ROCK signaling in regulating the pathological conditions of asthma and thus SUMOylation is an additional target for the therapeutic intervention of this disease.
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Affiliation(s)
- Dan Tan
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Key Laboratory of CFDA for Respiratory Drug Research, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Meiping Lu
- National Clinical Research Center for Child Health, the Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China.
| | - Yuqing Cai
- National Clinical Research Center for Child Health, the Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Weibo Qi
- Department of Thoracic Surgery, the Affiliated Hospital of Jiaxing University, Jiaxing, 314001, China
| | - Fugen Wu
- Department of Paediatrics, the First People's Hospital of Wenling City, Wenling City, 317500, China
| | - Hangyang Bao
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Meiyu Qv
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Qiangqiang He
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yana Xu
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Xiangzhi Wang
- National Clinical Research Center for Child Health, the Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Tingyu Shen
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jiahao Luo
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yangxun He
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Junsong Wu
- Department of Critical Care Medicine, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, China
| | - Lanfang Tang
- National Clinical Research Center for Child Health, the Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China
| | - Muhammad Qasim Barkat
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Chengyun Xu
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- Key Laboratory of CFDA for Respiratory Drug Research, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- National Clinical Research Center for Child Health, the Children's Hospital of Zhejiang University School of Medicine, Hangzhou, 310053, China.
| | - Ximei Wu
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- Key Laboratory of CFDA for Respiratory Drug Research, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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Chen G, Li Q, Webb TI, Hollywood MA, Yan J. BK channel modulation by positively charged peptides and auxiliary γ subunits mediated by the Ca2+-bowl site. J Gen Physiol 2023; 155:e202213237. [PMID: 37130264 PMCID: PMC10163825 DOI: 10.1085/jgp.202213237] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 01/12/2023] [Accepted: 04/13/2023] [Indexed: 05/04/2023] Open
Abstract
The large-conductance, Ca2+-, and voltage-activated K+ (BK) channel consists of the pore-forming α (BKα) subunit and regulatory β and γ subunits. The γ1-3 subunits facilitate BK channel activation by shifting the voltage-dependence of channel activation toward the hyperpolarization direction by about 50-150 mV in the absence of Ca2+. We previously found that the intracellular C-terminal positively charged regions of the γ subunits play important roles in BK channel modulation. In this study, we found that the intracellular C-terminal region of BKα is indispensable in BK channel modulation by the γ1 subunit. Notably, synthetic peptide mimics of the γ1-3 subunits' C-terminal positively charged regions caused 30-50 mV shifts in BKα channel voltage-gating toward the hyperpolarization direction. The cationic cell-penetrating HIV-1 Tat peptide exerted a similar BK channel-activating effect. The BK channel-activating effects of the synthetic peptides were reduced in the presence of Ca2+ and markedly ablated by both charge neutralization of the Ca2+-bowl site and high ionic strength, suggesting the involvement of electrostatic interactions. The efficacy of the γ subunits in BK channel modulation was reduced by charge neutralization of the Ca2+-bowl site. However, BK channel modulation by the γ1 subunit was little affected by high ionic strength and the positively charged peptide remained effective in BK channel modulation in the presence of the γ1 subunit. These findings identify positively charged peptides as BK channel modulators and reveal a role for the Ca2+-bowl site in BK channel modulation by positively charged peptides and the C-terminal positively charged regions of auxiliary γ subunits.
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Affiliation(s)
- Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Timothy I. Webb
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A. Hollywood
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Neuroscience and Biochemistry and Cell Biology Graduate Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, TX, USA
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Liu Y, Yu Z, Zhu L, Ma S, Luo Y, Liang H, Liu Q, Chen J, Guli S, Chen X. Orchestration of MUC2 - The key regulatory target of gut barrier and homeostasis: A review. Int J Biol Macromol 2023; 236:123862. [PMID: 36870625 DOI: 10.1016/j.ijbiomac.2023.123862] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023]
Abstract
The gut mucosa of human is covered by mucus, functioning as a crucial defense line for the intestine against external stimuli and pathogens. Mucin2 (MUC2) is a subtype of secretory mucins generated by goblet cells and is the major macromolecular component of mucus. Currently, there is an increasing interest on the investigations of MUC2, noting that its function is far beyond a maintainer of the mucus barrier. Moreover, numerous gut diseases are associated with dysregulated MUC2 production. Appropriate production level of MUC2 and mucus contributes to gut barrier function and homeostasis. The production of MUC2 is regulated by a series of physiological processes, which are orchestrated by various bioactive molecules, signaling pathways and gut microbiota, etc., forming a complex regulatory network. Incorporating the latest findings, this review provided a comprehensive summary of MUC2, including its structure, significance and secretory process. Furthermore, we also summarized the molecular mechanisms of the regulation of MUC2 production aiming to provide developmental directions for future researches on MUC2, which can act as a potential prognostic indicator and targeted therapeutic manipulation for diseases. Collectively, we elucidated the micro-level mechanisms underlying MUC2-related phenotypes, hoping to offer some constructive guidance for intestinal and overall health of mankind.
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Affiliation(s)
- Yaxin Liu
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Zihan Yu
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Lanping Zhu
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Shuang Ma
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Yang Luo
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Huixi Liang
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Qinlingfei Liu
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Jihua Chen
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Sitan Guli
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China
| | - Xin Chen
- Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China; Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Anshan Road 154, Heping District, Tianjin 300052, China.
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8
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Fu R, Wang L, Meng Y, Xue W, Liang J, Peng Z, Meng J, Zhang M. Apigenin remodels the gut microbiota to ameliorate ulcerative colitis. Front Nutr 2022; 9:1062961. [PMID: 36590200 PMCID: PMC9800908 DOI: 10.3389/fnut.2022.1062961] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Introduction Ulcerative colitis (UC), a chronic non-specific colorectal inflammatory disease with unclear etiology, has long plagued human health. Gut microbiota dysbiosis destroy homeostasis of the colon, which is closely related to ulcerative colitis progress. Apigenin, a flavonoid widely present in celery, has been found to improve ulcerative colitis. However, the potential molecular mechanism of apigenin ameliorating ulcerative colitis through protecting intestinal barrier and regulating gut microbiota remains undefined. Methods Dextran sodium sulfate (DSS)-induced colitis mouse model was conducted to evaluate the effect of apigenin on UC. Disease activity index score of mice, colon tissue pathological, cytokines analysis, intestinal tight junction proteins expression, and colonic content short-chain fatty acids (SCFAs) and 16S rRNA gene sequencing were conducted to reflect the protection of apigenin on UC. Results The results indicated that apigenin significantly relieved the intestinal pathological injury, increased goblet cells quantity and mucin secretion, promoted anti-inflammatory cytokines IL-10 expression, and inhibited the expression of proinflammatory cytokines, TNF-α, IL-1β, IL-6 and MPO activity of colon tissue. Apigenin increased ZO-1, claudin-1 and occludin expressions to restore the integrity of the intestinal barrier. Moreover, apigenin remodeled the disordered gut microbiota by regulating the abundance of Akkermansia, Turicibacter, Klebsiella, Romboutsia, etc., and its metabolites (SCFAs), attenuating DSS-induced colon injury. We also investigated the effect of apigenin supplementation on potential metabolic pathways of gut microbiota. Conclusion Apigenin effectively ameliorated DSS-induced UC via balancing gut microbiome to inhibit inflammation and protect gut barrier. With low toxicity and high efficiency, apigenin might serve as a potential therapeutic strategy for the treatment of UC via regulating the interaction and mechanism between host and microorganism.
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Affiliation(s)
- Rongrong Fu
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Lechen Wang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Ying Meng
- Department of Rehabilitation Medicine, Shandong Provincial Third Hospital, Shandong University, Jinan, Shandong, China
| | - Wenqing Xue
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Jingjie Liang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Zimu Peng
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Jing Meng
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China,Tianjin International Joint Academy of Biomedicine, Tianjin, China,*Correspondence: Jing Meng,
| | - Min Zhang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China,China-Russia Agricultural Processing Joint Laboratory, Tianjin Agricultural University, Tianjin, China,Min Zhang,
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9
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Feng J, Xie Z, Hu H. Ion channel regulation of gut immunity. J Gen Physiol 2022; 155:213734. [PMID: 36459135 PMCID: PMC9723512 DOI: 10.1085/jgp.202113042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 08/15/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
Mounting evidence indicates that gastrointestinal (GI) homeostasis hinges on communications among many cellular networks including the intestinal epithelium, the immune system, and both intrinsic and extrinsic nerves innervating the gut. The GI tract, especially the colon, is the home base for gut microbiome which dynamically regulates immune function. The gut's immune system also provides an effective defense against harmful pathogens entering the GI tract while maintaining immune homeostasis to avoid exaggerated immune reaction to innocuous food and commensal antigens which are important causes of inflammatory disorders such as coeliac disease and inflammatory bowel diseases (IBD). Various ion channels have been detected in multiple cell types throughout the GI tract. By regulating membrane properties and intracellular biochemical signaling, ion channels play a critical role in synchronized signaling among diverse cellular components in the gut that orchestrates the GI immune response. This work focuses on the role of ion channels in immune cells, non-immune resident cells, and neuroimmune interactions in the gut at the steady state and pathological conditions. Understanding the cellular and molecular basis of ion channel signaling in these immune-related pathways and initial testing of pharmacological intervention will facilitate the development of ion channel-based therapeutic approaches for the treatment of intestinal inflammation.
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Affiliation(s)
- Jing Feng
- Department of Anesthesiology, The Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO,Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China,Correspondence to Jing Feng:
| | - Zili Xie
- Department of Anesthesiology, The Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO
| | - Hongzhen Hu
- Department of Anesthesiology, The Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO,Hongzhen Hu:
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10
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Gonzalez-Perez V, Zhou Y, Ciorba MA, Lingle CJ. The LRRC family of BK channel regulatory subunits: potential roles in health and disease. J Physiol 2022; 600:1357-1371. [PMID: 35014034 PMCID: PMC8930516 DOI: 10.1113/jp281952] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/04/2022] [Indexed: 11/08/2022] Open
Abstract
Large conductance K+ channels, termed BK channels, regulate a variety of cellular and physiological functions. Although universally activated by changes in voltage or [Ca2+ ]i , the threshold for BK channel activation varies among loci of expression, often arising from cell-specific regulatory subunits including a family of leucine rich repeat-containing (LRRC) γ subunits (LRRC26, LRRC52, LRRC55 and LRRC38). The 'founding' member of this family, LRRC26, was originally identified as a tumour suppressor in various cancers. An LRRC26 knockout (KO) mouse model recently revealed that LRRC26 is also highly expressed in secretory epithelial cells and partners with BK channels in the salivary gland and colonic goblet cells to promote sustained K+ fluxes likely essential for normal secretory function. To accomplish this, LRRC26 negatively shifts the range of BK channel activation such that channels contribute to K+ flux near typical epithelial cell resting conditions. In colon, the absence of LRRC26 increases vulnerability to colitis. LRRC26-containing BK channels are also likely important regulators of epithelial function in other loci, including airways, female reproductive tract and mammary gland. Based on an LRRC52 KO mouse model, LRRC52 regulation of large conductance K+ channels plays a role both in sperm function and in cochlear inner hair cells. Although our understanding of LRRC-containing BK channels remains rudimentary, KO mouse models may help define other organs in which LRRC-containing channels support normal function. A key topic for future work concerns identification of endogenous mechanisms, whether post-translational or via gene regulation, that may impact LRRC-dependent pathologies.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
| | - Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
| | - Matthew A. Ciorba
- Department of Internal Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis MO 63110 USA
| | - Christopher J. Lingle
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
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11
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Chen G, Li Q, Yan J. The leucine-rich repeat domains of BK channel auxiliary γ subunits regulate their expression, trafficking, and channel-modulation functions. J Biol Chem 2022; 298:101664. [PMID: 35104503 PMCID: PMC8892010 DOI: 10.1016/j.jbc.2022.101664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/16/2022] [Accepted: 01/26/2022] [Indexed: 11/25/2022] Open
Abstract
As high-conductance calcium- and voltage-dependent potassium channels, BK channels consist of pore-forming, voltage-, and Ca2+-sensing α and auxiliary subunits. The leucine-rich repeat (LRR) domain-containing auxiliary γ subunits potently modulate the voltage dependence of BK channel activation. Despite their dominant size in whole protein masses, the function of the LRR domain in BK channel γ subunits is unknown. We here investigated the function of these LRR domains in BK channel modulation by the auxiliary γ1-3 (LRRC26, LRRC52, and LRRC55) subunits. Using cell surface protein immunoprecipitation, we validated the predicted extracellular localization of the LRR domains. We then refined the structural models of mature proteins on the membrane via molecular dynamic simulations. By replacement of the LRR domain with extracellular regions or domains of non-LRR proteins, we found that the LRR domain is nonessential for the maximal channel-gating modulatory effect but is necessary for the all-or-none phenomenon of BK channel modulation by the γ1 subunit. Mutational and enzymatic blockade of N-glycosylation in the γ1-3 subunits resulted in a reduction or loss of BK channel modulation by γ subunits. Finally, by analyzing their expression in whole cells and on the plasma membrane, we found that blockade of N-glycosylation drastically reduced total expression of the γ2 subunit and the cell surface expression of the γ1 and γ3 subunits. We conclude that the LRR domains play key roles in the regulation of the expression, cell surface trafficking, and channel-modulation functions of the BK channel γ subunits.
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Affiliation(s)
- Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; Graduate Programs of Neuroscience and Biochemistry and Cell Biology, The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, Texas, USA.
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12
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Shah KR, Guan X, Yan J. Structural and Functional Coupling of Calcium-Activated BK Channels and Calcium-Permeable Channels Within Nanodomain Signaling Complexes. Front Physiol 2022; 12:796540. [PMID: 35095560 PMCID: PMC8795833 DOI: 10.3389/fphys.2021.796540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 12/28/2021] [Indexed: 11/13/2022] Open
Abstract
Biochemical and functional studies of ion channels have shown that many of these integral membrane proteins form macromolecular signaling complexes by physically associating with many other proteins. These macromolecular signaling complexes ensure specificity and proper rates of signal transduction. The large-conductance, Ca2+-activated K+ (BK) channel is dually activated by membrane depolarization and increases in intracellular free Ca2+ ([Ca2+]i). The activation of BK channels results in a large K+ efflux and, consequently, rapid membrane repolarization and closing of the voltage-dependent Ca2+-permeable channels to limit further increases in [Ca2+]i. Therefore, BK channel-mediated K+ signaling is a negative feedback regulator of both membrane potential and [Ca2+]i and plays important roles in many physiological processes and diseases. However, the BK channel formed by the pore-forming and voltage- and Ca2+-sensing α subunit alone requires high [Ca2+]i levels for channel activation under physiological voltage conditions. Thus, most native BK channels are believed to co-localize with Ca2+-permeable channels within nanodomains (a few tens of nanometers in distance) to detect high levels of [Ca2+]i around the open pores of Ca2+-permeable channels. Over the last two decades, advancement in research on the BK channel’s coupling with Ca2+-permeable channels including recent reports involving NMDA receptors demonstrate exemplary models of nanodomain structural and functional coupling among ion channels for efficient signal transduction and negative feedback regulation. We hereby review our current understanding regarding the structural and functional coupling of BK channels with different Ca2+-permeable channels.
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Affiliation(s)
- Kunal R. Shah
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Xin Guan
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Jiusheng Yan
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- Neuroscience Program, Graduate School of Biomedical Sciences, UT Health, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- Biochemistry and Cell Biology Program, Graduate School of Biomedical Sciences, UT Health, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- *Correspondence: Jiusheng Yan,
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13
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Vouga AG, Rockman ME, Yan J, Jacobson MA, Rothberg BS. State-dependent inhibition of BK channels by the opioid agonist loperamide. J Gen Physiol 2021; 153:212539. [PMID: 34357374 PMCID: PMC8352719 DOI: 10.1085/jgp.202012834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 04/19/2021] [Accepted: 07/08/2021] [Indexed: 12/20/2022] Open
Abstract
Large-conductance Ca2+-activated K+ (BK) channels control a range of physiological functions, and their dysfunction is linked to human disease. We have found that the widely used drug loperamide (LOP) can inhibit activity of BK channels composed of either α-subunits (BKα channels) or α-subunits plus the auxiliary γ1-subunit (BKα/γ1 channels), and here we analyze the molecular mechanism of LOP action. LOP applied at the cytosolic side of the membrane rapidly and reversibly inhibited BK current, an effect that appeared as a decay in voltage-activated BK currents. The apparent affinity for LOP decreased with hyperpolarization in a manner consistent with LOP behaving as an inhibitor of open, activated channels. Increasing LOP concentration reduced the half-maximal activation voltage, consistent with relative stabilization of the LOP-inhibited open state. Single-channel recordings revealed that LOP did not reduce unitary BK channel current, but instead decreased BK channel open probability and mean open times. LOP elicited use-dependent inhibition, in which trains of brief depolarizing steps lead to accumulated reduction of BK current, whereas single brief depolarizing steps do not. The principal effects of LOP on BK channel gating are described by a mechanism in which LOP acts as a state-dependent pore blocker. Our results suggest that therapeutic doses of LOP may act in part by inhibiting K+ efflux through intestinal BK channels.
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Affiliation(s)
- Alexandre G Vouga
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Michael E Rockman
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Marlene A Jacobson
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia PA
| | - Brad S Rothberg
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
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