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Liu Y, Wu D, Zheng H, Ni Y, Zhu L, Jiang Y, Dai J, Sun Q, Zhao Y, Zhang Q, Yang Y, Liu R. Serum Spexin Level Is Negatively Associated With Peripheral Neuropathy and Sensory Pain in Type 2 Diabetes. J Diabetes Res 2024; 2024:4538199. [PMID: 38919263 PMCID: PMC11199070 DOI: 10.1155/2024/4538199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 04/17/2024] [Accepted: 04/20/2024] [Indexed: 06/27/2024] Open
Abstract
Background: Spexin is a novel peptide hormone and has shown antinociceptive effects in experimental mice. This study is aimed at evaluating the association of serum spexin level with diabetic peripheral neuropathy (DPN) and related pain in a Chinese population. Methods: We enrolled 167 type 2 diabetes mellitus (T2DM) including 56 patients without DPN (non-DPN), 67 painless DPN, and 44 painful DPN. Serum spexin was measured using ELISA. Logistic regression models were performed to analyze the independent effects of spexin on prevalence of DPN and painful DPN. In streptozotocin (STZ)-induced diabetic mice, mechanical pain threshold was measured using electronic von Frey aesthesiometer. Human peripheral blood mononuclear cells (PBMCs) were isolated and further stimulated with lipopolysaccharide without or with spexin. The gene expression was assayed by qPCR. Results: Compared with non-DPN, serum spexin level decreased in painless DPN and further decreased in painful DPN. The odds of DPN was associated with low spexin level in T2DM, which was similar by age, sex, BMI, and diabetes duration, but attenuated in smokers. The odds of having pain was associated with decreased spexin level in DPN, which was similar by age, sex, smoking status, and diabetes duration, but attenuated in normal weight. Furthermore, we observed that mechanical pain threshold increased in spexin-treated diabetic mice. We also found that lipopolysaccharide treatment increased the mRNA level of TNF-α, IL-6, and MCP-1 in human PBMCs, while spexin treatment prevented this increase. Conclusions: These results suggested that spexin might serve as a protective factor for diabetes against neuropathology and pain-related pathogenesis.
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Affiliation(s)
- Ying Liu
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Di Wu
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Hangping Zheng
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Yunzhi Ni
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Lu Zhu
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Yaojing Jiang
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Jiarong Dai
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Quanya Sun
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Ying Zhao
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Qi Zhang
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Yehong Yang
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
| | - Rui Liu
- Department of Endocrinology and MetabolismHuashan HospitalFudan University, Shanghai 200040, China
- Institute of Endocrinology and DiabetesFudan University, Shanghai 200040, China
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Pu F, Guo H, Shi D, Chen F, Peng Y, Huang X, Liu J, Zhang Z, Shao Z. The generation and use of animal models of osteosarcoma in cancer research. Genes Dis 2024; 11:664-674. [PMID: 37692517 PMCID: PMC10491873 DOI: 10.1016/j.gendis.2022.12.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 12/16/2022] [Indexed: 09/12/2023] Open
Abstract
Osteosarcoma is the most common malignant bone tumor affecting children and adolescents. Currently, the most common treatment is surgery combined with neoadjuvant chemotherapy. Although the survival rate of patients with osteosarcoma has improved in recent years, it remains poor when the tumor(s) progress and distant metastases develop. Therefore, better animal models that more accurately replicate the natural progression of the disease are needed to develop improved prognostic and diagnostic markers, as well as targeted therapies for both primary and metastatic osteosarcoma. The present review described animal models currently being used in research investigating osteosarcoma, and their characteristics, advantages, and disadvantages. These models may help elucidate the pathogenic mechanism(s) of osteosarcoma and provide evidence to support and develop clinical treatment strategies.
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Affiliation(s)
- Feifei Pu
- Department of Orthopedics, Wuhan Hospital of Traditional Chinese and Western Medicine (Wuhan No.1 Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Haoyu Guo
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Deyao Shi
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Fengxia Chen
- Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, China
| | - Yizhong Peng
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Xin Huang
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Jianxiang Liu
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Zhicai Zhang
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Zengwu Shao
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
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Li M, Ma Z, Zhang Y, Feng H, Li Y, Sang W, Zhu R, Huang R, Yan J. Integrative analysis of the ST6GALNAC family identifies GATA2-upregulated ST6GALNAC5 as an adverse prognostic biomarker promoting prostate cancer cell invasion. Cancer Cell Int 2023; 23:141. [PMID: 37468844 DOI: 10.1186/s12935-023-02983-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 06/29/2023] [Indexed: 07/21/2023] Open
Abstract
BACKGROUND ST6GALNAC family members function as sialyltransferases and have been implicated in cancer progression. However, their aberrant expression levels, prognostic values and specific roles in metastatic prostate cancer (PCa) remain largely unclear. METHODS Two independent public datasets (TCGA-PRAD and GSE21032), containing 648 PCa samples in total, were employed to comprehensively examine the mRNA expression changes of ST6GALNAC family members in PCa, as well as their associations with clinicopathological parameters and prognosis. The dysregulation of ST6GALNAC5 was further validated in a mouse PCa model and human PCa samples from our cohort (n = 64) by immunohistochemistry (IHC). Gene Set Enrichment Analysis, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and drug sensitivity analyses were performed to enrich the biological processes most related to ST6GALNAC5. Sulforhodamine B, transwell, luciferase reporter and chromatin immunoprecipitation (ChIP) assays were used to examine the PCa cell proliferation, invasion and transcriptional regulation, respectively. RESULTS Systematical investigation of six ST6GALNAC family members in public datasets revealed that ST6GALNAC5 was the only gene consistently and significantly upregulated in metastatic PCa, and ST6GALNAC5 overexpression was also positively associated with Gleason score and predicted poor prognosis in PCa patients. IHC results showed that (1) ST6GALNAC5 protein expression was increased in prostatic intraepithelial neoplasia and further elevated in PCa from a PbCre;PtenF/F mouse model; (2) overexpressed ST6GALNAC5 protein was confirmed in human PCa samples comparing with benign prostatic hyperplasia samples from our cohort (p < 0.001); (3) ST6GALNAC5 overexpression was significantly correlated with perineural invasion of PCa. Moreover, we first found transcription factor GATA2 positively and directly regulated ST6GALNAC5 expression at transcriptional level. ST6GALNAC5 overexpression could partially reverse GATA2-depletion-induced inhibition of PCa cell invasion. The GATA2-ST6GALNAC5 signature exhibited better prediction on the poor prognosis in PCa patients than GATA2 or ST6GALNAC5 alone. CONCLUSIONS Our results indicated that GATA2-upregulated ST6GALNAC5 might serve as an adverse prognostic biomarker promoting prostate cancer cell invasion.
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Affiliation(s)
- Meiqian Li
- Model Animal Research Center, Medical School of Nanjing University, Nanjing University, Nanjing, China
| | - Zhihui Ma
- Center for Drug Safety Evaluation and Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yuqing Zhang
- Department of Urology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Hanyi Feng
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yang Li
- Department of Urology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Weicong Sang
- Department of Urology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Rujian Zhu
- Department of Urology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
| | - Ruimin Huang
- Center for Drug Safety Evaluation and Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, China.
| | - Jun Yan
- Department of Laboratory Animal Science, Fudan University, Shanghai, China.
- Department of Urology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
- Model Animal Research Center, Nanjing University, Nanjing, China.
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Assefa F. The role of sensory and sympathetic nerves in craniofacial bone regeneration. Neuropeptides 2023; 99:102328. [PMID: 36827755 DOI: 10.1016/j.npep.2023.102328] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/21/2023]
Abstract
Multiple factors regulate the regeneration of craniofacial bone defects. The nervous system is recognized as one of the critical regulators of bone mass, thereby suggesting a role for neuronal pathways in bone regeneration. However, in the context of craniofacial bone regeneration, little is known about the interplay between the nervous system and craniofacial bone. Sensory and sympathetic nerves interact with the bone through their neuropeptides, neurotransmitters, proteins, peptides, and amino acid derivates. The neuron-derived factors, such as semaphorin 3A (SEMA3A), substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and vasoactive intestinal peptide (VIP), possess a remarkable role in craniofacial regeneration. This review summarizes the roles of these factors and recently published factors such as secretoneurin (SN) and spexin (SPX) in the osteoblast and osteoclast differentiation, bone metabolism, growth, remodeling and discusses the novel application of nerve-based craniofacial bone regeneration. Moreover, the review will facilitate understanding the mechanism of action and provide potential treatment direction for the craniofacial bone defect.
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Affiliation(s)
- Freshet Assefa
- Department of Biochemistry, Collage of Medicine and Health Sciences, Hawassa University, P.O.Box 1560, Hawassa, Ethiopia.
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Peng J, Wu Y, E Q, Zhou Z, Wen X. RNA-seq analysis revealed genes associated with neuropathic pain induced by chronic compressive injury in interferon regulatory factors 4 knockout mice. Hum Exp Toxicol 2023; 42:9603271231221567. [PMID: 38073479 DOI: 10.1177/09603271231221567] [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] [Indexed: 12/18/2023]
Abstract
OBJECTIVE To explore the differential expression of genes between wild-type chronic compressive injury (CCI) mice (WT-CCI) and interferon regulatory factors 4 (IRF4) knockout CCI mice (KO-CCI) by RNA-seq analysis of the mouse spinal cord. METHODS RNA-seq analysis of the spinal cord tissue of the chronic sciatic nerve ligation mice and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were used. RESULTS A total of 104 genes were up-regulated and 116 genes were down-regulated in spinal cord of the mice in IRF4 knockout (KO-CCI) group compared with that in the wild-type CCI (WT-CCI) group. There were 1472 differentially expressed genes in the biological process group, 62 differentially expressed genes in the cellular component group, and 163 differentially expressed genes in the molecular function group in KO-CCI mice. A total of 14 genes related to inflammatory reactions were differentially expressed. Real-time PCR results confirmed that Pparg and Grpr mRNA expression was up-regulated and Arg 1 and Ccl11 mRNA expression was down-regulated in the KO-CCI group. CONCLUSION IRF4 is involved in neuropathic pain in CCI mice, IRF4 may participate in neuropathic pain by regulating Grpr, Mas1, Galr3, Nos2, Arg1, Ccl11, Ptgs2, S100a8, Pparg, Cd40, Has2, Gpr151, Il123a, Capns2, Ankrd1, Ccnb1, and Nppb genes.
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Affiliation(s)
- Jiayi Peng
- Department of Anesthesiology, Second People`s Hospital of Foshan City, Foshan, China
| | - Yunlin Wu
- Department of Anesthesiology, Second People`s Hospital of Foshan City, Foshan, China
- Graduate School, Guangdong Medical University, Zhanjiang, China
| | - Qi E
- Department of Anesthesiology, Second People`s Hospital of Foshan City, Foshan, China
| | - Ziyin Zhou
- Department of Anesthesiology, Second People`s Hospital of Foshan City, Foshan, China
| | - Xianjie Wen
- Department of Anesthesiology, Second People`s Hospital of Foshan City, Foshan, China
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Assefa F, Kim JA, Lim J, Nam SH, Shin HI, Park EK. The Neuropeptide Spexin Promotes the Osteoblast Differentiation of MC3T3-E1 Cells via the MEK/ERK Pathway and Bone Regeneration in a Mouse Calvarial Defect Model. Tissue Eng Regen Med 2021; 19:189-202. [PMID: 34951679 PMCID: PMC8782952 DOI: 10.1007/s13770-021-00408-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/20/2021] [Accepted: 10/24/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The neural regulation of bone regeneration has emerged recently. Spexin (SPX) is a novel neuropeptide and regulates multiple biological functions. However, the effects of SPX on osteogenic differentiation need to be further investigated. Therefore, the aim of this study is to investigate the effects of SPX on osteogenic differentiation, possible underlying mechanisms, and bone regeneration. METHODS In this study, MC3T3-E1 cells were treated with various concentrations of SPX. Cell proliferation, osteogenic differentiation marker expressions, alkaline phosphatase (ALP) activity, and mineralization were evaluated using the CCK-8 assay, reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), ALP staining, and alizarin red S staining, respectively. To determine the underlying molecular mechanism of SPX, the phosphorylation levels of signaling molecules were examined via western blot analysis. Moreover, in vivo bone regeneration by SPX (0.5 and 1 µg/µl) was evaluated in a calvarial defect model. New bone formation was analyzed using micro-computed tomography (micro-CT) and histology. RESULTS The results indicated that cell proliferation was not affected by SPX. However, SPX significantly increased ALP activity, mineralization, and the expression of genes for osteogenic differentiation markers, including runt-related transcription factor 2 (Runx2), Alp, collagen alpha-1(I) chain (Col1a1), osteocalcin (Oc), and bone sialoprotein (Bsp). In contrast, SPX downregulated the expression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (Enpp1). Moreover, SPX upregulated phosphorylated mitogen-activated protein kinase kinase (MEK1/2) and extracellular signal-regulated kinase (ERK1/2). In vivo studies, micro-CT and histologic analysis revealed that SPX markedly increased a new bone formation. CONCLUSION Overall, these results demonstrated that SPX stimulated osteogenic differentiation in vitro and increased in vivo bone regeneration via the MEK/ERK pathway.
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Affiliation(s)
- Freshet Assefa
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea
| | - Ju Ang Kim
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea
| | - Jiwon Lim
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea
| | - Sang-Hyeon Nam
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea
| | - Hong-In Shin
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea
| | - Eui Kyun Park
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Korea.
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Chen Y, He M, Lei MML, Ko WKW, Lin C, Bian Z, Wong AOL. Mouse Spexin: (III) Differential Regulation by Glucose and Insulin in Glandular Stomach and Functional Implication in Feeding Control. Front Endocrinol (Lausanne) 2021; 12:681648. [PMID: 34025589 PMCID: PMC8138665 DOI: 10.3389/fendo.2021.681648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/19/2021] [Indexed: 11/24/2022] Open
Abstract
Spexin (SPX), a neuropeptide with diverse functions, is a novel satiety factor in fish models and its role in feeding control has been recently confirmed in mammals. In mouse, food intake was shown to trigger SPX expression in glandular stomach with parallel rise in serum SPX and these SPX signals could inhibit feeding via central actions within the hypothalamus. However, the mechanisms for SPX regulation by food intake are still unclear. To examine the role of insulin signal caused by glucose uptake in SPX regulation, the mice were IP injected with glucose and insulin, respectively. In this case, serum SPX was elevated by glucose but not altered by insulin. Meanwhile, SPX transcript expression in the glandular stomach was up-regulated by glucose but the opposite was true for insulin treatment. Using in situ hybridization, the differential effects on SPX gene expression were located in the gastric mucosa of glandular stomach. Co-injection experiments also revealed that glucose stimulation on serum SPX and SPX mRNA expressed in glandular stomach could be blocked by insulin. In gastric mucosal cells prepared from glandular stomach, the opposite effects on SPX transcript expression by glucose and insulin could still be noted with similar blockade of the stimulatory effects of glucose by insulin. In this cell model, SPX gene expression induced by glucose was mediated by glucose uptake via GLUT, ATP synthesis by glycolysis/respiratory chain, and subsequent modulation of KATP channel activity, but the voltage-sensitive Ca2+ channels were not involved. The corresponding inhibition by insulin, however, was mediated by PI3K/Akt, MEK1/2/ERK1/2, and P38MAPK cascades coupled to insulin receptor but not IGF-1 receptor. Apparently, glucose uptake in mice can induce SPX expression in the glandular stomach through ATP synthesis via glucose metabolism and subsequent modification of KATP channel activity, which may contribute to SPX release into circulation to act as the satiety signal after food intake. The insulin rise caused by glucose uptake, presumably originated from the pancreas, may serve as a negative feedback to inhibit the SPX response by activating MAPK and PI3K/Akt pathways in the stomach.
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Affiliation(s)
- Yuan Chen
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Mulan He
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Martina M. L. Lei
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Wendy K. W. Ko
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Chengyuan Lin
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Zhaoxiang Bian
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Anderson O. L. Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
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Mills EG, Izzi-Engbeaya C, Abbara A, Comninos AN, Dhillo WS. Functions of galanin, spexin and kisspeptin in metabolism, mood and behaviour. Nat Rev Endocrinol 2021; 17:97-113. [PMID: 33273729 DOI: 10.1038/s41574-020-00438-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/21/2020] [Indexed: 02/07/2023]
Abstract
The bioactive peptides galanin, spexin and kisspeptin have a common ancestral origin and their pathophysiological roles are increasingly the subject of investigation. Evidence suggests that these bioactive peptides play a role in the regulation of metabolism, pancreatic β-cell function, energy homeostasis, mood and behaviour in several species, including zebrafish, rodents and humans. Galanin signalling suppresses insulin secretion in animal models (but not in humans), is potently obesogenic and plays putative roles governing certain evolutionary behaviours and mood modulation. Spexin decreases insulin secretion and has potent anorectic, analgesic, anxiolytic and antidepressive-like effects in animal models. Kisspeptin modulates glucose-stimulated insulin secretion, food intake and/or energy expenditure in animal models and humans. Furthermore, kisspeptin is implicated in the control of reproductive behaviour in animals, modulation of human sexual and emotional brain processing, and has antidepressive and fear-suppressing effects. In addition, galanin-like peptide is a further member of the galaninergic family that plays emerging key roles in metabolism and behaviour. Therapeutic interventions targeting galanin, spexin and/or kisspeptin signalling pathways could therefore contribute to the treatment of conditions ranging from obesity to mood disorders. However, many gaps and controversies exist, which must be addressed before the therapeutic potential of these bioactive peptides can be established.
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Affiliation(s)
- Edouard G Mills
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - Chioma Izzi-Engbeaya
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, UK
| | - Ali Abbara
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, UK
| | - Alexander N Comninos
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, UK
| | - Waljit S Dhillo
- Section of Endocrinology and Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK.
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, UK.
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Li M, Zhang X, Li C, Liu Y, Yang S, Xu S. Galanin Receptor 2 Is Involved in Galanin-Induced Analgesic Effect by Activating PKC and CaMKII in the Nucleus Accumbens of Inflammatory Pain Rats. Front Neurosci 2021; 14:593331. [PMID: 33551722 PMCID: PMC7859109 DOI: 10.3389/fnins.2020.593331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 12/28/2020] [Indexed: 11/13/2022] Open
Abstract
It has been reported that galanin has an analgesic effect via activating galanin receptors (GALRs). This study focused on the involvement of GALR2 in the galanin-induced analgesic effect and its signaling mechanism in the nucleus accumbens (NAc) of inflammatory rats. Animal models were established through injecting carrageenan into the plantar of rats’ left hind paw. The results showed that GALR2 antagonist M871 weakened partially the galanin-induced increases in hind paw withdrawal latency (HWL) to thermal stimulation and hind paw withdrawal threshold (HWT) to mechanical stimulation in NAc of inflammatory rats. Moreover, the GALR2 agonist M1145 prolonged the HWL and HWT, while M871 blocked the M1145-induced increases in HWL and HWT. Western blotting showed that the phosphorylation of calcium/calmodulin-dependent protein kinase II (p-CaMKII) and protein kinase C (p-PKC) in NAc were upregulated after carrageenan injection, while p-PKC and p-CaMKII were downregulated after intra-NAc administration of M871. Furthermore, the CaMKII inhibitor KN93 and PKC inhibitor GO6983 attenuated M1145-induced increases in HWL and HWT in NAc of rats with inflammatory pain. These results prove that GALR2 is involved in the galanin-induced analgesic effect by activating CaMKII and PKC in NAc of inflammatory pain rats, implying that GALR2 agonists probably are potent therapeutic options for inflammatory pain.
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Affiliation(s)
- Mengnan Li
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Xiaomin Zhang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Chongyang Li
- Department of Oncology, Affiliated Hospital, Yunnan University, Kunming, China
| | - Yanan Liu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Shuang Yang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Shilian Xu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
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Wong MKH, Chen Y, He M, Lin C, Bian Z, Wong AOL. Mouse Spexin: (II) Functional Role as a Satiety Factor inhibiting Food Intake by Regulatory Actions Within the Hypothalamus. Front Endocrinol (Lausanne) 2021; 12:681647. [PMID: 34276562 PMCID: PMC8283969 DOI: 10.3389/fendo.2021.681647] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/13/2021] [Indexed: 11/17/2022] Open
Abstract
Spexin (SPX) is a pleiotropic peptide with highly conserved protein sequence from fish to mammals and its biological actions are mediated by GalR2/GalR3 receptors expressed in target tissues. Recently, SPX has been confirmed to be a novel satiety factor in fish species but whether the peptide has a similar function in mammals is still unclear. Using the mouse as a model, the functional role of SPX in feeding control and the mechanisms involved were investigated. After food intake, serum SPX in mice could be up-regulated with elevations of transcript expression and tissue content of SPX in the glandular stomach but not in other tissues examined. As revealed by immunohistochemical staining, food intake also intensified SPX signals in the major cell types forming the gastric glands (including the foveolar cells, parietal cells, and chief cells) within the gastric mucosa of glandular stomach. Furthermore, IP injection of SPX was effective in reducing food intake with parallel attenuation in transcript expression of NPY, AgRP, NPY type 5 receptor (NPY5R), and ghrelin receptor (GHSR) in the hypothalamus, and these inhibitory effects could be blocked by GalR3 but not GalR2 antagonism. In agreement with the central actions of SPX, similar inhibition on feeding and hypothalamic expression of NPY, AgRP, NPY5R, and GHSR could also be noted with ICV injection of SPX. In the same study, in contrast to the drop in NPY5R and GHSR, SPX treatment could induce parallel rises of transcript expression of leptin receptor (LepR) and melanocortin 4 receptor (MC4R) in the hypothalamus. These findings, as a whole, suggest that the role of SPX as a satiety factor is well conserved in the mouse. Apparently, food intake can induce SPX production in glandular stomach and contribute to the postprandial rise of SPX in circulation. Through GalR3 activation, this SPX signal can act within the hypothalamus to trigger feedback inhibition on feeding by differential modulation of feeding regulators (NPY and AgRP) and their receptors (NPY5R, GHSR, LepR, and MC4R) involved in the feeding circuitry within the CNS.
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Affiliation(s)
- Matthew K. H. Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Yuan Chen
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Mulan He
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Chengyuan Lin
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Zhaoxiang Bian
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Anderson O. L. Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
- *Correspondence: Anderson O. L. Wong,
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Wong MKH, He M, Sze KH, Huang T, Ko WKW, Bian ZX, Wong AOL. Mouse Spexin: (I) NMR Solution Structure, Docking Models for Receptor Binding, and Histological Expression at Tissue Level. Front Endocrinol (Lausanne) 2021; 12:681646. [PMID: 34276561 PMCID: PMC8285161 DOI: 10.3389/fendo.2021.681646] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/27/2021] [Indexed: 01/10/2023] Open
Abstract
Spexin (SPX), a highly conserved neuropeptide, is known to have diverse functions and has been implicated/associated with pathological conditions, including obesity, diabetes, anorexia nervosa, and anxiety/mood disorders. Although most of the studies on SPX involved the mouse model, the solution structure of mouse SPX, structural aspects for SPX binding with its receptors GalR2/3, and its cellular expression/distribution in mouse tissues are largely unknown. Using CD and NMR spectroscopies, the solution structure of mouse SPX was shown to be in the form of a helical peptide with a random coil from Asn1 to Pro4 in the N-terminal followed by an α-helix from Gln5 to Gln14 in the C-terminus. The molecular surface of mouse SPX is largely hydrophobic with Lys11 as the only charged residue in the α-helix. Based on the NMR structure obtained, docking models of SPX binding with mouse GalR2 and GalR3 were constructed by homology modeling and MD simulation. The models deduced reveal that the amino acids in SPX, especially Asn1, Leu8, and Leu10, could interact with specific residues in ECL1&2 and TMD2&7 of GalR2 and GalR3 by H-bonding/hydrophobic interactions, which provides the structural evidence to support the idea that the two receptors can act as the cognate receptors for SPX. For tissue distribution of SPX, RT-PCR based on 28 tissues/organs harvested from the mouse demonstrated that SPX was ubiquitously expressed at the tissue level with notable signals detected in the brain, GI tract, liver, gonad, and adrenal gland. Using immunohistochemical staining, protein signals of SPX could be located in the liver, pancreas, white adipose tissue, muscle, stomach, kidney, spleen, gonad, adrenal, and hypothalamo-pituitary axis in a cell type-specific manner. Our results, as a whole, not only can provide the structural information for ligand/receptor interaction for SPX but also establish the anatomical basis for our on-going studies to examine the physiological functions of SPX in the mouse model.
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Affiliation(s)
- Matthew K. H. Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Mulan He
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Kong Hung Sze
- Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong, Hong Kong
| | - Tao Huang
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Wendy K. W. Ko
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Zhao-Xiang Bian
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, Hong Kong
| | - Anderson O. L. Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, Hong Kong
- *Correspondence: Anderson O. L. Wong,
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Xu L, Jiang H, Feng Y, Cao P, Ke J, Long X. Peripheral and central substance P expression in rat CFA-induced TMJ synovitis pain. Mol Pain 2020; 15:1744806919866340. [PMID: 31322474 PMCID: PMC6685108 DOI: 10.1177/1744806919866340] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Synovitis contributes to temporomandibular joint (TMJ) pain, nevertheless, the detailed nociceptive mechanism remains unclear. In this study, a rat model of TMJ synovitis was induced by intra-articular injection with complete Freund’s adjuvant (CFA). After CFA-induced synovitis, pain behaviors were observed. Then, TMJ, trigeminal ganglion, and trigeminal nucleus caudalis (TNC) tissues were collected, and immunohistochemistry was used to detect the expression of substance P (SP) and protein gene product 9.5 (PGP9.5) in the synovium tissue. Furthermore, the gene expression level of SP and PGP9.5 in synovium was detected by reverse transcription-polymerase chain reaction (RT-PCR). Afterwards, the expression of SP in the trigeminal ganglion and TNC and c-fos in the TNC was detected by immunohistochemistry. Compared with the control group, the expression of SP and PGP9.5 nerve fibers density and gene levels of them in the synovium tissue were significantly increased in CFA-induced TMJ synovitis rats. Similarly, SP expression in the trigeminal ganglion and TNC, and c-fos expression in the TNC were also obviously increased in CFA-induced TMJ synovitis rats. Collectively, CFA-induced rat TMJ synovitis resulted in obvious pain. This nociceptive reaction could be attributed to the augmented quantity of SP and PGP9.5 positive-stained nerve fibers distributed in the inflammatory synovium as well as enhanced SP expression in the trigeminal ganglion and TNC tissue. c-fos expression in the rat TNC illustrates CFA-induced TMJ synovitis can evoke the acute pain.
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Affiliation(s)
- Liqin Xu
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Henghua Jiang
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yaping Feng
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Pinyin Cao
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jin Ke
- 1 State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Xing Long
- 2 Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China
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Lv S, Zhou Y, Feng Y, Zhang X, Wang X, Yang Y, Wang X. Peripheral Spexin Inhibited Food Intake in Mice. Int J Endocrinol 2020; 2020:4913785. [PMID: 32831833 PMCID: PMC7426757 DOI: 10.1155/2020/4913785] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/31/2020] [Accepted: 06/15/2020] [Indexed: 11/17/2022] Open
Abstract
Spexin (SPX, NPQ), a novel endogenous neuropeptide, was firstly identified by bioinformatics. Spexin gene and protein widely distributed in the central nervous system and peripheral tissues, such as the hypothalamus and digestive tract. The role of spexin in appetite regulation in mammalian is still unclear. The present study was designed to investigate the mechanism and effect of peripheral spexin on food intake in mice. During the light period, an intraperitoneal (i.p.) injection of spexin (10 nmol/mouse) significantly inhibited cumulative food intake at 2, 4, and 6 h after treatment in fasted mice. During the dark period, spexin (1 and 10 nmol/mouse, i.p.) significantly suppressed cumulative food intake at 4 and 6 h after treatment in freely feeding mice. The GALR3 antagonist SNAP37889, not GALR2 antagonist, significantly antagonized the inhibitory effect on cumulative food intake (0-6 h) induced by spexin. Spexin significantly reduced the mRNA level of Npy mRNA, not Agrp, Pomc, Cart, Crh, Orexin, or Mch, in the hypothalamus. Spexin (10 nmol/mouse, i.p.) increased the number of c-Fos positive neurons in hypothalamic AHA and SCN, but not in ARC, DMN, LHA, PVN, SON, or VMH. The hypothalamic p-CaMK2 protein expression was upregulated by spexin. This study indicated that acute peripheral injection of spexin inhibited mouse food intake. The anorectic effect may be mediated by GALR3, and inhibiting neuropeptide Y (NPY) via p-CaMK2 and c-Fos in the hypothalamus.
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Affiliation(s)
- Shuangyu Lv
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Yuchen Zhou
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Yu Feng
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Xiaomei Zhang
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Xinyue Wang
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Yanjie Yang
- Institute of Molecular Medicine, School of Basic Medical Sciences, Henan University, Kaifeng 475004, China
| | - Xinchun Wang
- The First Affiliated Hospital of Henan University, Kaifeng 475001, China
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Jeong I, Kim E, Seong JY, Park HC. Overexpression of Spexin 1 in the Dorsal Habenula Reduces Anxiety in Zebrafish. Front Neural Circuits 2019; 13:53. [PMID: 31474838 PMCID: PMC6702259 DOI: 10.3389/fncir.2019.00053] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/26/2019] [Indexed: 01/01/2023] Open
Abstract
Spexin (SPX) is an evolutionarily conserved neuropeptide that is expressed in the mammalian brain and peripheral tissue. Two orthologs are present in the teleost, SPX1 and SPX2. SPX1 is involved in reproduction and food intake. Recently, SPX1 neurons have been found to be located in the specific nuclei of dorsal habenula (dHb) and to project into the interpeduncular nucleus (IPN), in which galanin receptor 2a/2b (GALR2a/2b) expression was also observed. This indicates that habenula SPX1 neurons may interact with GALR2a/2b in the IPN; however, the function of SPX1 in the dHb-IPN neuronal circuit remains unknown. To determine the role of SPX1 in the dHb-IPN neural circuit, we generated transgenic zebrafish overexpressing SPX1 specifically in the dHb. We found that transgenic zebrafish overexpressing SPX1 in the dHb had anxiolytic behaviors compared with their wildtype siblings. Furthermore, quantitative PCR revealed that mRNA expression of galr2a and galr2b in the IPN and serotonin-related genes in the raphe was upregulated in the brains of transgenic zebrafish. Taken together, our data suggest that SPX1 function in the dHb-IPN neural circuits is implicated in the regulation of anxiety behaviors via modulation of the serotoninergic system in zebrafish.
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Affiliation(s)
- Inyoung Jeong
- Department of Biomedical Sciences, College of Medicine, Korea University, Ansan, South Korea
| | - Eunmi Kim
- Department of Biomedical Sciences, College of Medicine, Korea University, Ansan, South Korea
| | - Jae Young Seong
- Department of Biomedical Sciences, Korea University, Seoul, South Korea
| | - Hae-Chul Park
- Department of Biomedical Sciences, College of Medicine, Korea University, Ansan, South Korea
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Lv SY, Zhou YC, Zhang XM, Chen WD, Wang YD. Emerging Roles of NPQ/Spexin in Physiology and Pathology. Front Pharmacol 2019; 10:457. [PMID: 31133851 PMCID: PMC6514225 DOI: 10.3389/fphar.2019.00457] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 04/11/2019] [Indexed: 01/25/2023] Open
Abstract
Spexin (SPX), also called neuropeptide Q (NPQ), is a novel endogenous neuropeptide. Spexin gene and protein are widely expressed in central nervous system and peripheral tissues in humans, rodents, goldfish, etc. A few of physiological and pathological roles of spexin are gradually emerged recently. This article summarized the roles of spexin in feeding behavior, gastrointestinal motility, obesity, diabetes, energy metabolism, endocrine, mental diseases, and cardiovascular function. Given the broad roles of spexin, this neuropeptide has attracted much interest from investigators and will be as a promising future target for novel therapeutic research and drug design.
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Affiliation(s)
- Shuang-Yu Lv
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University, Kaifeng, China
| | - Yu-Chen Zhou
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University, Kaifeng, China
| | - Xiao-Mei Zhang
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University, Kaifeng, China
| | - Wei-Dong Chen
- Key Laboratory of Receptors-Mediated Gene Regulation and Drug Discovery, School of Medicine, Henan University, Kaifeng, China.,Key Laboratory of Molecular Pathology, School of Basic Medical Science, Inner Mongolia Medical University, Hohhot, China
| | - Yan-Dong Wang
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
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Lim CH, Lee MYM, Soga T, Parhar I. Evolution of Structural and Functional Diversity of Spexin in Mammalian and Non-mammalian Vertebrate Species. Front Endocrinol (Lausanne) 2019; 10:379. [PMID: 31275244 PMCID: PMC6593056 DOI: 10.3389/fendo.2019.00379] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 05/28/2019] [Indexed: 01/15/2023] Open
Abstract
Spexin (SPX) is a novel neuropeptide, which was first identified in the human genome using bioinformatics. Since then, orthologs of human SPX have been identified in mammalian and non-mammalian vertebrates. The mature sequence of SPX, NWTPQAMLYLKGAQ, is evolutionally conserved across vertebrate species, with some variations in teleost species where Ala at position 13 is substituted by Thr. In mammals, the gene structure of SPX comprises six exons and five introns, however, variation exists within non-mammalian species, goldfish and zebrafish having five exons while grouper has six exons. Phylogenetic and synteny analysis, reveal that SPX is grouped together with two neuropeptides, kisspeptin (KISS) and galanin (GAL) as a family of peptides with a common evolutionary ancestor. A paralog of SPX, termed SPX2 has been identified in non-mammalians but not in the mammalian genome. Ligand-receptor interaction study also shows that SPX acts as a ligand for GAL receptor 2 (2a and 2b in non-mammalian vertebrates) and 3. SPX acts as a neuromodulator with multiple central and peripheral physiological roles in the regulation of insulin release, fat metabolism, feeding behavior, and reproduction. Collectively, this review provides a comprehensive overview of the evolutionary diversity as well as molecular and physiological roles of SPX in mammalian and non-mammalian vertebrate species.
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