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Lam LH, Li W, Wu WC, Chow KC, Au WYD, Xu G, Wang G, Qian X, Ng KM, Nawabjan SA, Gandhi Sethuraman MI, Choi WY, Chow BKC, Leung SO, Hui CW. SM17, a new IL-17RB-targeting antibody, ameliorates disease progression in a mouse model of atopic dermatitis. Allergy 2024. [PMID: 38590291 DOI: 10.1111/all.16120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/25/2024] [Accepted: 03/30/2024] [Indexed: 04/10/2024]
Affiliation(s)
| | - Weimin Li
- SinoMab BioScience Limited, Hong Kong, China
| | | | | | | | - Guolin Xu
- MediNexus Pharma (Suzhou) Limited, Suzhou, Jiangsu, China
| | - Ge Wang
- MediNexus Pharma (Suzhou) Limited, Suzhou, Jiangsu, China
| | - Xuchen Qian
- MediNexus Pharma (Suzhou) Limited, Suzhou, Jiangsu, China
| | - Ka Man Ng
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | | | | | - Wai Yan Choi
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
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2
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Zhang F, Qiao W, Wei JA, Tao Z, Chen C, Wu Y, Lin M, Ng KMC, Zhang L, Yeung KWK, Chow BKC. Secretin-dependent signals in the ventromedial hypothalamus regulate energy metabolism and bone homeostasis in mice. Nat Commun 2024; 15:1030. [PMID: 38310104 PMCID: PMC10838336 DOI: 10.1038/s41467-024-45436-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 01/22/2024] [Indexed: 02/05/2024] Open
Abstract
Secretin, though originally discovered as a gut-derived hormone, is recently found to be abundantly expressed in the ventromedial hypothalamus, from which the central neural system controls satiety, energy metabolism, and bone homeostasis. However, the functional significance of secretin in the ventromedial hypothalamus remains unclear. Here we show that the loss of ventromedial hypothalamus-derived secretin leads to osteopenia in male and female mice, which is primarily induced by diminished cAMP response element-binding protein phosphorylation and upregulation in peripheral sympathetic activity. Moreover, the ventromedial hypothalamus-secretin inhibition also contributes to hyperphagia, dysregulated lipogenesis, and impaired thermogenesis, resulting in obesity in male and female mice. Conversely, overexpression of secretin in the ventromedial hypothalamus promotes bone mass accrual in mice of both sexes. Collectively, our findings identify an unappreciated secretin signaling in the central neural system for the regulation of energy and bone metabolism, which may serve as a new target for the clinical management of obesity and osteoporosis.
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Affiliation(s)
- Fengwei Zhang
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
| | - Wei Qiao
- Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, the University of Hong Kong, Hong Kong, China.
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, the University of Hong Kong-Shenzhen Hospital, Shenzhen, China.
| | - Ji-An Wei
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
- Key Laboratory of CNS Regeneration (Ministry of Education), GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Zhengyi Tao
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
| | - Congjia Chen
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
| | - Yefeng Wu
- Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, the University of Hong Kong, Hong Kong, China
| | - Minghui Lin
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
| | - Ka Man Carmen Ng
- School of Biological Sciences, the University of Hong Kong, Hong Kong, China
| | - Li Zhang
- Key Laboratory of CNS Regeneration (Ministry of Education), GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
- Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, China
| | - Kelvin Wai-Kwok Yeung
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, the University of Hong Kong-Shenzhen Hospital, Shenzhen, China.
- Department of Orthopaedics and Traumatology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, the University of Hong Kong, Hong Kong, China.
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3
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Zhang F, Tao Z, Chen C, Chow BKC. Effects of secretin gene knockout on the diversity, composition, and function of gut microbiota in adult male mice. Front Cell Infect Microbiol 2023; 13:1257857. [PMID: 38156312 PMCID: PMC10753818 DOI: 10.3389/fcimb.2023.1257857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 11/16/2023] [Indexed: 12/30/2023] Open
Abstract
The gut microbiota plays a vital role in maintaining gastrointestinal homeostasis, however, whether it is influenced by gut hormones remains unknown. Secretin is a well-known gastrointestinal hormone produced by enteroendocrine S cells. This study utilized 16S rRNA amplicon sequencing to characterize the effect of SCT deficiency on the gut microbiota. Our results show that systemic SCT knockout alters the composition and abundance of the mouse gut microbiota but does not affect fecal short-chain fatty acids and lipids concentrations. At the genus level, the abundance of Turicibacter, Bacteroides, Ruminococcu, Romboutsia, Asaccharobacter, and Parasutterella increased in SCT-/- mice, whereas the abundance of Akkermansia and Escherichia decreased. Functional prediction results showed that lack of SCT reduced the abundance of carbohydrate metabolism-related pathways but increased the abundance of linoleic acid metabolism and branched-chain amino acid degradation. Overall, systemic SCT knockout had only minor effects on gut microbiota composition and function in adult male mice fed a standard chow diet.
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Affiliation(s)
- Fengwei Zhang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | | | | | - Billy Kwok Chong Chow
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
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4
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Su Y, Luo Y, Zhang P, Lin H, Pu W, Zhang H, Wang H, Hao Y, Xiao Y, Zhang X, Wei X, Nie S, Zhang K, Fu Q, Chen H, Huang N, Ren Y, Wu M, Chow BKC, Chen X, Jin W, Wang F, Zhao L, Rao F. Glucose-induced CRL4 COP1-p53 axis amplifies glycometabolism to drive tumorigenesis. Mol Cell 2023:S1097-2765(23)00432-X. [PMID: 37390815 DOI: 10.1016/j.molcel.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 04/19/2023] [Accepted: 06/06/2023] [Indexed: 07/02/2023]
Abstract
The diabetes-cancer association remains underexplained. Here, we describe a glucose-signaling axis that reinforces glucose uptake and glycolysis to consolidate the Warburg effect and overcome tumor suppression. Specifically, glucose-dependent CK2 O-GlcNAcylation impedes its phosphorylation of CSN2, a modification required for the deneddylase CSN to sequester Cullin RING ligase 4 (CRL4). Glucose, therefore, elicits CSN-CRL4 dissociation to assemble the CRL4COP1 E3 ligase, which targets p53 to derepress glycolytic enzymes. A genetic or pharmacologic disruption of the O-GlcNAc-CK2-CSN2-CRL4COP1 axis abrogates glucose-induced p53 degradation and cancer cell proliferation. Diet-induced overnutrition upregulates the CRL4COP1-p53 axis to promote PyMT-induced mammary tumorigenesis in wild type but not in mammary-gland-specific p53 knockout mice. These effects of overnutrition are reversed by P28, an investigational peptide inhibitor of COP1-p53 interaction. Thus, glycometabolism self-amplifies via a glucose-induced post-translational modification cascade culminating in CRL4COP1-mediated p53 degradation. Such mutation-independent p53 checkpoint bypass may represent the carcinogenic origin and targetable vulnerability of hyperglycemia-driven cancer.
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Affiliation(s)
- Yang Su
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yifan Luo
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China; School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Peitao Zhang
- Department of Thyroid and Neck Oncology, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, Tianjin, China
| | - Hong Lin
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Weijie Pu
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Hongyun Zhang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Huifang Wang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yi Hao
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yihang Xiao
- School of Science, Westlake University, Westlake Laboratory of Life Sciences and Biomedicine, and Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Xiaozhe Zhang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiayun Wei
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Siyue Nie
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Keren Zhang
- BGI-Shenzhen, Beishan Industrial Zone 11th building, Yantian District, Shenzhen, Guangdong, 518083, China
| | - Qiuyu Fu
- National Institute of Biological Sciences, Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Hao Chen
- Department of Human Cell Biology and Genetics, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Niu Huang
- National Institute of Biological Sciences, Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Yan Ren
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Mingxuan Wu
- School of Science, Westlake University, Westlake Laboratory of Life Sciences and Biomedicine, and Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | | | - Xing Chen
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenfei Jin
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Fengchao Wang
- National Institute of Biological Sciences, Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China.
| | - Li Zhao
- Department of Thyroid and Neck Oncology, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, Tianjin, China.
| | - Feng Rao
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China.
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5
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Liu Y, Wei JA, Luo Z, Cui J, Luo Y, Mak SOK, Wang S, Zhang F, Yang Y, So KF, Shi L, Zhang L, Chow BKC. A gut-brain axis mediates sodium appetite via gastrointestinal peptide regulation on a medulla-hypothalamic circuit. Sci Adv 2023; 9:eadd5330. [PMID: 36791202 PMCID: PMC9931223 DOI: 10.1126/sciadv.add5330] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 01/17/2023] [Indexed: 05/29/2023]
Abstract
Salt homeostasis is orchestrated by both neural circuits and peripheral endocrine factors. The colon is one of the primary sites for electrolyte absorption, while its potential role in modulating sodium intake remains unclear. Here, we revealed that a gastrointestinal hormone, secretin, is released from colon endocrine cells under body sodium deficiency and is indispensable for inducing salt appetite. As the neural substrate, circulating secretin activates specific receptors in the nucleus of the solitary tracts, which further activates the downstream paraventricular nucleus of the hypothalamus, resulting in enhanced sodium intake. These results demonstrated a previously unrecognized gut-brain pathway for the timely regulation of sodium homeostasis.
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Affiliation(s)
- Yuchu Liu
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Ji-an Wei
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Zhihua Luo
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Jing Cui
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Yifan Luo
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Sarah Oi Kwan Mak
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Siqi Wang
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Fengwei Zhang
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Yan Yang
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Kwok-Fai So
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
- Center for Brain Science and Brain-Inspired Intelligence, Guangdong-Hong Kong-Macao Greater Bay Area, Guangzhou, China
- Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, China
- State Key Laboratory of Brain and Cognitive Science, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Lingling Shi
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Li Zhang
- Key Laboratory of CNS Regeneration (Ministry of Education), Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China
- Center for Brain Science and Brain-Inspired Intelligence, Guangdong-Hong Kong-Macao Greater Bay Area, Guangzhou, China
- Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, China
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6
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Zhang F, Mak SOK, Liu Y, Ke Y, Rao F, Yung WH, Zhang L, Chow BKC. Secretin receptor deletion in the subfornical organ attenuates the activation of excitatory neurons under dehydration. Curr Biol 2022; 32:4832-4841.e5. [PMID: 36220076 DOI: 10.1016/j.cub.2022.09.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 07/22/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022]
Abstract
In mammals, thirst is strongly influenced by the subfornical organ (SFO), a forebrain structure that integrates circulating signals including osmotic pressure and sodium contents. Secretin (SCT), a classical gastrointestinal hormone, has been implicated as a humoral factor regulating body-fluid homeostasis. However, the neural mechanism of secretin in the central nervous system in managing thirst remains unclear. In this study, we report that the local ablation of SCT receptor (SCTR) in the SFO reduces water but not salt intake in dehydrated mice and this effect could not be rescued by exogenous SCT administration. Electrophysiology with single-cell RT-PCR indicates that SCT elicits inward currents in the SFO neuronal nitric oxide synthase (SFOnNOS) neurons via SCTR in the presence of glutamate receptor antagonists. We further show that the SCTR in the SFO permits the activation of SFOnNOS neurons under distinct thirst types. Projection-specific gene deletion of SCTR in SFO to the median preoptic nucleus (MnPO) pathway also reduces water intake in dehydrated animals. SCT signaling thus plays an indispensable role in driving thirst. These data not only expand the functional boundaries of SCTR but also provide insights into the central mechanisms of homeostatic regulation.
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Affiliation(s)
- Fengwei Zhang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Sarah O K Mak
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Yuchu Liu
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Ya Ke
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Feng Rao
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Wing Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China; Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong, China.
| | - Li Zhang
- Key Laboratory of CNS Regeneration (Ministry of Education), GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China; Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, China.
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7
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Lin H, Yan Y, Luo Y, So WY, Wei X, Zhang X, Yang X, Zhang J, Su Y, Yang X, Zhang B, Zhang K, Jiang N, Chow BKC, Han W, Wang F, Rao F. IP 6-assisted CSN-COP1 competition regulates a CRL4-ETV5 proteolytic checkpoint to safeguard glucose-induced insulin secretion. Nat Commun 2021; 12:2461. [PMID: 33911083 PMCID: PMC8080631 DOI: 10.1038/s41467-021-22941-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 04/08/2021] [Indexed: 12/18/2022] Open
Abstract
COP1 and COP9 signalosome (CSN) are the substrate receptor and deneddylase of CRL4 E3 ligase, respectively. How they functionally interact remains unclear. Here, we uncover COP1–CSN antagonism during glucose-induced insulin secretion. Heterozygous Csn2WT/K70E mice with partially disrupted binding of IP6, a CSN cofactor, display congenital hyperinsulinism and insulin resistance. This is due to increased Cul4 neddylation, CRL4COP1 E3 assembly, and ubiquitylation of ETV5, an obesity-associated transcriptional suppressor of insulin secretion. Hyperglycemia reciprocally regulates CRL4-CSN versus CRL4COP1 assembly to promote ETV5 degradation. Excessive ETV5 degradation is a hallmark of Csn2WT/K70E, high-fat diet-treated, and ob/ob mice. The CRL neddylation inhibitor Pevonedistat/MLN4924 stabilizes ETV5 and remediates the hyperinsulinemia and obesity/diabetes phenotypes of these mice. These observations were extended to human islets and EndoC-βH1 cells. Thus, a CRL4COP1-ETV5 proteolytic checkpoint licensing GSIS is safeguarded by IP6-assisted CSN-COP1 competition. Deregulation of the IP6-CSN-CRL4COP1-ETV5 axis underlies hyperinsulinemia and can be intervened to reduce obesity and diabetic risk. Mediators of insulin signalling are targets of cullin-RING ubiquitin ligases (CRL) that mediate protein degradation, but the role of protein degradation in insulin signalling is incompletely understood. Here, the authors identified a glucose-responsive CRL4-COP1-ETV5 proteolytic axis that promotes insulin secretion, and is inhibited under hypoglycemia.
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Affiliation(s)
- Hong Lin
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yuan Yan
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yifan Luo
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China.,School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wing Yan So
- Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Xiayun Wei
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaozhe Zhang
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaoli Yang
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Jun Zhang
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yang Su
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiuyan Yang
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Bobo Zhang
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Kangjun Zhang
- Department of Hepatic Surgery, the Third People's Hospital of Shenzhen and the Second Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Nan Jiang
- Department of Hepatic Surgery, the Third People's Hospital of Shenzhen and the Second Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong, China
| | | | - Weiping Han
- Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Fengchao Wang
- National Institute of Biological Sciences, Beijing, China
| | - Feng Rao
- School of Life Sciences, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China.
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Ke R, Lok SIS, Singh K, Chow BKC, Janovjak H, Lee LTO. Formation of Kiss1R/GPER Heterocomplexes Negatively Regulates Kiss1R-mediated Signalling through Limiting Receptor Cell Surface Expression. J Mol Biol 2021; 433:166843. [PMID: 33539880 DOI: 10.1016/j.jmb.2021.166843] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/11/2021] [Accepted: 01/21/2021] [Indexed: 12/20/2022]
Abstract
Kisspeptin receptor (Kiss1R) is an important receptor that plays central regulatory roles in reproduction by regulating hormone release in the hypothalamus. We hypothesize that the formation of heterocomplexes between Kiss1R and other hypothalamus G protein-coupled receptors (GPCRs) affects their cellular signaling. Through screening of potential interactions between Kiss1R and hypothalamus GPCRs, we identified G protein-coupled estrogen receptor (GPER) as one interaction partner of Kiss1R. Based on the recognised function of kisspeptin and estrogen in regulating the reproductive system, we investigated the Kiss1R/GPER heterocomplex in more detail and revealed that complex formation significantly reduced Kiss1R-mediated signaling. GPER did not directly antagonize Kiss1R conformational changes upon ligand binding, but it rather reduced the cell surface expression of Kiss1R. These results therefore demonstrate a regulatory mechanism of hypothalamic hormone receptors via receptor cooperation in the reproductive system and modulation of receptor sensitivity.
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Affiliation(s)
- Ran Ke
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
| | - Samson Ian Sam Lok
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
| | - Kailash Singh
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Billy Kwok Chong Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region
| | - Harald Janovjak
- EMBL Australia, Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, Australia
| | - Leo Tsz On Lee
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau; Cancer Centre, Faculty of Health Sciences, University of Macau, Taipa, Macau.
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On JSW, Arokiaraj AWR, Chow BKC. Molecular evolution of CRH and CRHR subfamily before the evolutionary origin of vertebrate. Peptides 2019; 120:170087. [PMID: 31042548 DOI: 10.1016/j.peptides.2019.04.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 04/21/2019] [Accepted: 04/23/2019] [Indexed: 11/19/2022]
Abstract
Corticotropin-releasing hormone (CRH) is well-cited for its important role in governing the stress responses via neuroendocrine system in vertebrates. After the identification of homologs of CRH receptor (CRHR) in both deuterostome and arthropod lineages, it was suggested that the ancestral homolog of CRH-CRHR molecular system is present in the bilaterian. However, homolog sequences from arthropods differ considerably from vertebrate CRH-like peptide sequences. Due to the significant difference between the biological system, as well as the gene regulatory network, of protostome and that of vertebrate, physiological studies on the protostomes may not provide important insight into the evolutionary history of vertebrate CRH system, while tunicate and amphioxus, two close relatives to vertebrate, which have diverged before two rounds of whole genome duplication (2WGDs) do. Given the identification of amphioxus CRH-like peptide by our group, this review aims to reexamine the current hypotheses on the evolution of CRH subfamily. It is generally accepted that paralogs of CRH and CRHR have been produced through 2WGDs, which occurred during the early vertebrate evolution. The identification of a single crh-like gene in amphioxi and tunicates by in silico search and the presence of two paralogons with a total of 5 crh-like genes in gnathostomes has shown that an additional duplication event might have happened to the ancestral crh-like gene before 2WGDs. On the other hand, the evolution of crhr gene subfamily appears to be mainly influenced by 2WGDs and only two receptor genes have been retained in the genomes of jawed vertebrates.
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Affiliation(s)
- Jason Sai Wun On
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
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10
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Sekar R, Wang L, Chow BKC. Corrigendum: Central Control of Feeding Behavior by the Secretin, PACAP, and Glucagon Family of Peptides. Front Endocrinol (Lausanne) 2018; 9:395. [PMID: 30057570 PMCID: PMC6058019 DOI: 10.3389/fendo.2018.00395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 11/13/2022] Open
Abstract
[This corrects the article DOI: 10.3389/fendo.2017.00018.].
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11
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Abstract
Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard open-chest transverse aortic constriction (TAC). Although transverse aortic constriction is a highly functional method for the induction of high pressure in the left ventricle, it is a more difficult and lengthy procedure due to its use of artificial ventilation with tracheal intubation. TAC is oftentimes also less survivable, as the newer method, MTAC, neither requires the cutting of the ribs and intercostal muscles nor tracheal intubation with a ventilation setup. In MTAC, as opposed to a thoracotomy to access to the chest cavity, the aortic arch is reached through a midline incision in the anterior neck. The thyroid is pulled back to reveal the sternal notch. The sternum is subsequently cut down to the second rib level, and the aortic arch is reached simply by separating the connective tissues and thymus. From there, a suture can be wrapped around the arch and tied with a spacer, and then the sternal cut and skin can be closed. MTAC is a much faster and less invasive way to induce left ventricular hypertension and enables the possibility for high-throughput studies. The success of the constriction can be verified using high-frequency trans-thoracic echocardiography, particularly color Doppler and pulsed-wave Doppler, to determine the flow velocities of the aortic arch and left and right carotid arteries, the dimension of the blood vessels, and the left ventricular function and morphology. A successful constriction will also trigger significant histopathological changes, such as cardiac muscle cell hypertrophy with interstitial and perivascular fibrosis. Here, the procedure of MTAC is described, demonstrating how the resulting flow changes in the carotid arteries can be examined with echocardiography, gross morphology, and histopathological changes in the heart.
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Affiliation(s)
- Aung Moe Zaw
- School of Biological Sciences, The University of Hong Kong
| | | | - Helen K W Law
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University
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12
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Sekar R, Wang L, Chow BKC. Central Control of Feeding Behavior by the Secretin, PACAP, and Glucagon Family of Peptides. Front Endocrinol (Lausanne) 2017; 8:18. [PMID: 28223965 PMCID: PMC5293785 DOI: 10.3389/fendo.2017.00018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/18/2017] [Indexed: 12/25/2022] Open
Abstract
Constituting a group of structurally related brain-gut peptides, secretin (SCT), pituitary adenylate cyclase-activating peptide (PACAP), and glucagon (GCG) family of peptide hormones exert their functions via interactions with the class B1 G protein-coupled receptors. In recent years, the roles of these peptides in neuroendocrine control of feeding behavior have been a specific area of research focus for development of potential therapeutic drug targets to combat obesity and metabolic disorders. As a result, some members in the family and their analogs have already been utilized as therapeutic agents in clinical application. This review aims to provide an overview of the current understanding on the important role of SCT, PACAP, and GCG family of peptides in central control of feeding behavior.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Lei Wang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
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13
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Zhang Q, Madden NE, Wong AST, Chow BKC, Lee LTO. The Role of Endocrine G Protein-Coupled Receptors in Ovarian Cancer Progression. Front Endocrinol (Lausanne) 2017; 8:66. [PMID: 28439256 PMCID: PMC5383648 DOI: 10.3389/fendo.2017.00066] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/23/2017] [Indexed: 01/01/2023] Open
Abstract
Ovarian cancer is the seventh most common cancer in women and the most lethal gynecological cancer, causing over 151,000 deaths worldwide each year. Dysregulated production of endocrine hormones, known to have pluripotent effects on cell function through the activation of receptor signaling pathways, is believed to be a high-risk factor for ovarian cancer. An increasing body of evidence suggests that endocrine G protein-coupled receptors (GPCRs) are involved in the progression and metastasis of ovarian neoplasms. GPCRs are attractive drug targets because their activities are regulated by more than 25% of all drugs approved by the Food and Drug Administration. Therefore, understanding the role of endocrine GPCRs during ovarian cancer progression and metastasis will allow for the development of novel strategies to design effective chemotherapeutic drugs against malignant ovarian tumors. In this review, we address the signaling pathways and functional roles of several key endocrine GPCRs that are related to the cause, progression, and metastasis of ovarian cancer.
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Affiliation(s)
- Qingyu Zhang
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
| | - Nadine Ellen Madden
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
| | - Alice Sze Tsai Wong
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | | | - Leo Tsz On Lee
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
- *Correspondence: Leo Tsz On Lee,
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14
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Sekar R, Singh K, Arokiaraj AWR, Chow BKC. Pharmacological Actions of Glucagon-Like Peptide-1, Gastric Inhibitory Polypeptide, and Glucagon. Int Rev Cell Mol Biol 2016; 326:279-341. [PMID: 27572131 DOI: 10.1016/bs.ircmb.2016.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Glucagon family of peptide hormones is a group of structurally related brain-gut peptides that exert their pleiotropic actions through interactions with unique members of class B1 G protein-coupled receptors (GPCRs). They are key regulators of hormonal homeostasis and are important drug targets for metabolic disorders such as type-2 diabetes mellitus (T2DM), obesity, and dysregulations of the nervous systems such as migraine, anxiety, depression, neurodegeneration, psychiatric disorders, and cardiovascular diseases. The current review aims to provide a detailed overview of the current understanding of the pharmacological actions and therapeutic advances of three members within this family including glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), and glucagon.
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Affiliation(s)
- R Sekar
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - K Singh
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - A W R Arokiaraj
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - B K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China.
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15
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Zhang L, Chung SK, Chow BKC. The knockout of secretin in cerebellar Purkinje cells impairs mouse motor coordination and motor learning. Neuropsychopharmacology 2014; 39:1460-8. [PMID: 24356714 PMCID: PMC3988549 DOI: 10.1038/npp.2013.344] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 12/16/2013] [Accepted: 12/16/2013] [Indexed: 11/09/2022]
Abstract
Secretin (SCT) was first considered to be a gut hormone regulating gastrointestinal functions when discovered. Recently, however, central actions of SCT have drawn intense research interest and are supported by the broad distribution of SCT in specific neuronal populations and by in vivo physiological studies regarding its role in water homeostasis and food intake. The direct action of SCT on a central neuron was first discovered in cerebellar Purkinje cells in which SCT from cerebellar Purkinje cells was found to potentiate GABAergic inhibitory transmission from presynaptic basket cells. Because Purkinje neurons have a major role in motor coordination and learning functions, we hypothesize a behavioral modulatory function for SCT. In this study, we successfully generated a mouse model in which the SCT gene was deleted specifically in Purkinje cells. This mouse line was tested together with SCT knockout and SCT receptor knockout mice in a full battery of behavioral tasks. We found that the knockout of SCT in Purkinje neurons did not affect general motor ability or the anxiety level in open field tests. However, knockout mice did exhibit impairments in neuromuscular strength, motor coordination, and motor learning abilities, as shown by wire hanging, vertical climbing, and rotarod tests. In addition, SCT knockout in Purkinje cells possibly led to the delayed development of motor neurons, as supported by the later occurrence of key neural reflexes. In summary, our data suggest a role in motor coordination and motor learning for SCT expressed in cerebellar Purkinje cells.
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Affiliation(s)
- Li Zhang
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China
| | - Sookja Kim Chung
- Department of Anatomy, University of Hong Kong, Hong Kong SAR, China
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16
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Abstract
Secretin family of peptide hormones is a group of structurally related brain-gut peptides that exert their functions via interactions with the class B1 G protein-coupled receptors (GPCRs). Recent researches of these peptides and receptors in metabolism have been an area of intense focus for the development of promising drug targets as therapeutic potentials for metabolic disorders. The fact that agonists of GLP-1, a member in the family, have already started being used as therapeutics clearly indicates the importance and relevance of further research on the clinical applications of these peptides. This review aims to provide an overview of the current understanding regarding the importance of this family of peptides as well as their receptors in metabolism with special focus on their actions in the hypothalamus.
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Affiliation(s)
- R Sekar
- School of Biological Sciences; The University of Hong Kong, Pokfulam, Hong Kong
| | - B K C Chow
- School of Biological Sciences; The University of Hong Kong, Pokfulam, Hong Kong
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17
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Cheng CYY, Chu JYS, Chow BKC. Central and peripheral administration of secretin inhibits food intake in mice through the activation of the melanocortin system. Neuropsychopharmacology 2011; 36:459-71. [PMID: 20927047 PMCID: PMC3055665 DOI: 10.1038/npp.2010.178] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Secretin (Sct) is released into the circulation postprandially from the duodenal S-cells. The major functions of Sct originated from the gastrointestinal system are to delay gastric emptying, stimulate fluid secretion from pancreas and liver, and hence optimize the digestion process. In recent years, Sct and its receptor (Sctr) have been identified in discrete nuclei of the hypothalamus, including the paraventricular nucleus (PVN) and the arcuate nucleus (Arc). These nuclei are the primary brain sites that are engaged in regulating body energy homeostasis, thus providing anatomical evidence to support a functional role of Sct in appetite control. In this study, the effect of Sct on feeding behavior was investigated using wild-type (wt), Sct(-/-), and secretin receptor-deficient (Sctr(-/-)) mice. We found that both central and peripheral administration of Sct could induce Fos expression in the PVN and Arc, suggesting the activation of hypothalamic feeding centers by this peptide. Consistent with this notion, Sct was found to increase thyrotropin-releasing hormone and melanocortin-4 receptor (Mc4r) transcripts in the PVN, and augment proopiomelanocortin, but reduces agouti-related protein mRNA expression in the Arc. Injection of Sct was able to suppress food intake in wt mice, but not in Sctr(-/-) mice, and that this effect was abolished upon pretreatment with SHU9119, an antagonist for Mc4r. In summary, our data suggest for the first time that Sct is an anorectic peptide, and that this function is mediated by the melanocortin system.
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Affiliation(s)
- Carrie Yuen Yee Cheng
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jessica Yan Shuen Chu
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Billy Kwok Chong Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China,School of Biological Sciences, The University of Hong Kong, 4N01, Kadoorie Biological Sciences Building, Pokfulam, Hong Kong SAR, China, Tel: +852 22990850, Fax: 852 25599114, E-mail:
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18
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Man C, Rosa J, Lee LTO, Lee VHY, Chow BKC, Lo KW, Doxsey S, Wu ZG, Kwong YL, Jin DY, Cheung ALM, Tsao SW. Latent membrane protein 1 suppresses RASSF1A expression, disrupts microtubule structures and induces chromosomal aberrations in human epithelial cells. Oncogene 2006; 26:3069-80. [PMID: 17099724 DOI: 10.1038/sj.onc.1210106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epstein-Barr virus (EBV) infection is closely associated with nasopharyngeal carcinoma (NPC) and can be detected in early premalignant lesions of nasopharyngeal epithelium. The latent membrane protein 1 (LMP1) is an oncoprotein encoded by the EBV and is believed to play a role in transforming premalignant nasopharyngeal epithelial cells into cancer cells. RASSF1A is a tumor-suppressor gene commonly inactivated in many types of human cancer including NPC. In this study, we report a novel function of LMP1, in down-regulating RASSF1A expression in human epithelial cells. Downregulation of RASSF1A expression by LMP1 is dependent on the activation of intracellular signaling of NF-kappaB involving the C-terminal activating regions (CTARs) of LMP1. LMP1 expression also suppresses the transcriptional activity of the RASSF1A core promoter. RASSF1A stabilizes microtubules and regulates mitotic events. Aberrant mitotic spindles and chromosome aberrations are reported phenotypes in RASSF1A inactivated cells. In this study, we observed that LMP1 expression in human epithelial cells could induce aberrant mitotic spindles, disorganized interphase microtubules and aneuploidy. LMP1 expression could also suppress microtubule dynamics as exemplified by tracking movements of the growing tips of microtubules in live cells by transfecting EGFP-tagged EB1 into cells. The aberrant mitotic spindles and interphase microtubule organization induced by LMP1 could be rescued by transfecting RASSF1A expression plasmid into cells. Downregulation of RASSF1A expression by LMP1 may facilitate its role in transformation of premalignant nasopharyngeal epithelial cells into cancer cells.
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Affiliation(s)
- C Man
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, People's Republic of China
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19
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Abstract
Previous studies demonstrated that secretin could be released from the cerebellum, where it exerts a facilitatory action on the GABAergic inputs into the Purkinje neurons. In the present article, we provide evidence of the endogenous release of secretin in the hypothalamus and the mechanisms underlying this release. Incubation of the hypothalamic explants with KCl induces the release of secretin to 4.35 +/- 0.45-fold of the basal level. This K+-induced release was tetrodotoxin and cadmium sensitive, suggesting the involvement of voltage-gated sodium and calcium channels. The use of specific blockers further revealed the involvement of L-, N-, and P-type high voltage-activated (HVA) calcium channels. Results present in the current article provide further and more solid evidence of the role of secretin as a neuropeptide in the mammalian central nervous system.
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Affiliation(s)
- J Y S Chu
- Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, PRC
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20
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Abstract
Secretin holds a unique place in the history of endocrinology and gastrointestinal physiology, as it is the first peptide designated as a hormone. During the last century since its first discovery, the hormonal effects of secretin in the gastrointestinal tract were extensively studied, and its principal role in the periphery was found to stimulate exocrine secretion from the pancreas. Recently, a functional role of secretin in the brain has also been substantiated, with evidence suggesting a possible role of secretin in embryonic brain development. Given that secretin and its receptors are widely expressed in multiple tissues, this peptide should therefore exhibit pleiotrophic functions throughout the body. The present article reviews the current knowledge on the central and peripheral effects of secretin as well as its therapeutic uses.
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Affiliation(s)
- J Y S Chu
- Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, PRC
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21
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Lee SMY, Chen L, Chow BKC, Yung WH. Endogenous release and multiple actions of secretin in the rat cerebellum. Neuroscience 2005; 134:377-86. [PMID: 15963647 DOI: 10.1016/j.neuroscience.2005.04.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Revised: 03/07/2005] [Accepted: 04/15/2005] [Indexed: 11/29/2022]
Abstract
Previous studies demonstrated that secretin could modulate synaptic transmission in the rat cerebellum. In the present report, we provide evidence for the endogenous release of secretin in the cerebellum and further characterize the actions of secretin in this brain area. First, to show that secretin is released endogenously, blocks of freshly dissected cerebella were challenged with a high concentration of KCl. Incubation with KCl almost doubled the rate of secretin release. This KCl-induced release was sensitive to tetrodotoxin and cadmium suggesting the involvement of voltage-gated sodium and calcium channels. The use of specific channel blockers further revealed that L-type and P/Q-type calcium channels underlie both basal and KCl-evoked secretin release. In support of this, depolarization of Purkinje neurons in the presence of NMDA, group II mGluR and cannabinoid CB1 receptor blockers resulted in increased inhibitory postsynaptic current frequency. Second, we found that the previously reported facilitatory action of secretin on GABAergic inputs to Purkinje neurons is partly dependent on the release of endogenous glutamate. In the presence of CNQX, an AMPA/kainate receptor antagonist, the facilitatory effect of secretin on GABA release was significantly reduced. In support of this idea, application of AMPA, but not kainate receptor agonist, facilitated GABA release from inhibitory terminals, an action that was sensitive to AMPA receptor antagonists. These data indicate that a direct and an indirect pathway mediate the action of secretin in the basket cell-Purkinje neuron synapse. The results provide further and more solid evidence for the role of secretin as a neuropeptide in the mammalian CNS.
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Affiliation(s)
- S M Y Lee
- Department of Zoology, The University of Hong Kong, Pokfulam, Hong Kong, China
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22
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Abstract
The expression and spatial distribution of secretin and its receptor in human cerebellum were investigated by in situ hybridization and immunohistochemical techniques. Secretin mRNAs are found in Purkinje cells whereas secretin receptor transcripts are present in Purkinje cells and basket cells in the molecular cell layer. In addition, secretin-immunoreactivities are localized in both the soma and dendrites of Purkinje cells. These data are the first demonstration of the spatial distribution of secretin and its receptor in distinct neurons within the human cerebellum. The cellular localizations of this ligand-receptor pair are consistent with the proposed actions of secretin in the cerebellum of rodents and hence suggest that secretin also serves specific neural functions in the human cerebellum.
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Affiliation(s)
- S M Y Lee
- Department of Zoology, Faculty of Science, The University of Hong Kong, Pokfulam, PR China
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23
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Chow BKC, Cheung KH, Tsang EMW, Leung MCT, Lee SMY, Wong PYD. Secretin Controls Anion Secretion in the Rat Epididymis in an Autocrine/Paracrine Fashion1. Biol Reprod 2004; 70:1594-9. [PMID: 14749298 DOI: 10.1095/biolreprod.103.024257] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
There is growing evidence that secretin, the first hormone discovered in our history, has functions in the brain other than in the gastrointestinal tract. This article reports for the first time that secretin and its receptor mRNAs are produced in distinct cell types within the epididymis. To test if secretin affects electrolyte transport in the epididymis, we measured short-circuit current (Isc) in cultured epididymal epithelia and found secretin dose-dependently stimulated Isc. Ion substitution experiments and use of pharmacological agents inferred that the stimulated Isc is a result of concurrent electrogenic chloride and bicarbonate secretion. It is further shown that secretin and pituitary adenylate cyclase-activating polypeptide (PACAP) function via totally different mechanisms: 1) PACAP works only from the apical side of the epithelium to stimulate chloride and not bicarbonate secretion, while secretin acts on the apical and basolateral sides to stimulate chloride and bicarbonate secretion. 2) the stimulation by PACAP but not secretin requires local prostaglandin synthesis. By immunocytochemical staining, secretin is localized in the principal cells of the initial segment and caput epididymidis, whereas secretin receptor is present in the principal cells of the proximal as well as the distal part of the epididymis. This pattern of distribution appears to be consistent with the idea that secretin is secreted by the proximal epididymis and acts on the proximal and distal epididymis in an autocrine and paracrine fashion. Its function is to control secretion of electrolytes and water.
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Affiliation(s)
- B K C Chow
- Department of Zoology, University of Hong Kong, Pokfulam, Hong Kong
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24
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Abstract
We have identified a second form of the type-II neuropeptide encoding a molt inhibiting hormone-like (MeeMIH-B) neuropeptide. MeeMIH-B showed only a 70% amino acid identity to the MIH-A (formerly MIH) isolated from the same species, suggesting a possible different function of the deduced neuropeptide. Like other neuropeptide members of the CHH family, the MIH-B gene consists of three exons separated by two introns. The levels of MIH-B mRNA transcript in the eyestalk decrease in the initial phase of gonad maturation and increase towards the end of maturation. The drop in MIH-B level suggests an inhibitory role for this neuropeptide in the initiation of vitellogenesis. MIH-B transcripts can also be detected in the brain, thoracic ganglion and ventral nerve cord. Together with the CHH-B peptide that we have previously described, this is the second peptide of the CHH family that can also be identified in the ventral nerve cord and in the XOSG complex. A recombinant MIH-B was produced and a polyclonal antibody against rMIH-B was subsequently generated. Specific anti-rMIH-B antiserum recognized the presence of MIH-B in the sinus gland, X-organs, as well as a giant neuron of the ventral nerve cord. Injection of rMIH-B delayed the molting cycle of the maturing female. Taken together, the results of this study suggest that a drop in MIH-B level may be required for the delay in the molting of the maturing females.
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Affiliation(s)
- P-L Gu
- Department of Zoology, The University of Hong Kong, Pokfulam Road, PR China
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Gunawardene YINS, Tobe SS, Bendena WG, Chow BKC, Yagi KJ, Chan SM. Function and cellular localization of farnesoic acid O-methyltransferase (FAMeT) in the shrimp, Metapenaeus ensis. Eur J Biochem 2002; 269:3587-95. [PMID: 12135499 DOI: 10.1046/j.1432-1033.2002.03048.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The isoprenoid methyl farnesoate (MF) has been implicated in the regulation of crustacean development and reproduction in conjunction with eyestalk molt inhibiting hormones and ecdysteroids. Farnesoic acid O-methyltransferase (FAMeT) catalyzes the methylation of farnesoic acid (FA) to produce MF in the terminal step of MF synthesis. We have previously cloned and characterized the shrimp FAMeT. In the present study, recombinant FAMeT (rFAMeT) was produced for bioassay and antiserum generation. FAMeT is widely distributed in shrimp tissues with the highest concentration observed in the ventral nerve cord. Interestingly, an additional larger protein in the eyestalk also showed immunoreactivity to anti-FAMeT serum. FAMeT was localized in the neurosecretory cells of the X-organ-sinus gland complex of the eyestalk. As shown by RT-PCR, FAMeT mRNA is constitutively expressed throughout the molt cycle in the eyestalk and the ventral nerve cord. To show that our cloned gene product had FAMeT activity, we demonstrated that expressed rFAMeT gene product catalyzed the conversion of FA to MF in a radiochemical assay. The ubiquitous distribution of FAMeT suggests that this enzyme is involved in physiological processes in addition to gametogenesis, oocyte maturation and development and metamorphosis of the shrimp. We hypothesize that FAMeT directly or indirectly (through MF) modulates the reproduction and growth of crustaceans by interacting with the eyestalk neuropeptides as a consequence of its presence in the neurosecretory cells of the X-organ-sinus gland.
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