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Li MR, Luo XJ, Peng J. Role of sonic hedgehog signaling pathway in the regulation of ion channels: focus on its association with cardio-cerebrovascular diseases. J Physiol Biochem 2023; 79:719-730. [PMID: 37676576 DOI: 10.1007/s13105-023-00982-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 08/25/2023] [Indexed: 09/08/2023]
Abstract
Sonic hedgehog (SHH) signaling is vital for cell differentiation and proliferation during embryonic development, yet its role in cardiac, cerebral, and vascular pathophysiology is under debate. Recent studies have demonstrated that several compounds of SHH signaling regulate ion channels, which in turn affect the behavior of target cells. Some of these ion channels are involved in the cardio-cerebrovascular system. Here, we first reviewed the SHH signaling cascades, then its interaction with ion channels, and their impact on cardio-cerebrovascular diseases. Considering the complex cross talk of SHH signaling with other pathways that also affect ion channels and their potential impact on the cardio-cerebrovascular system, we highlight the necessity of thoroughly studying the effect of SHH signaling on ion homeostasis, which could serve as a novel mechanism for cardio-cerebrovascular diseases. Activation of SHH signaling influence ion channels activity, which in turn influence ion homeostasis, membrane potential, and electrophysiology, could serve as a novel strategy for cardio-cerebrovascular diseases.
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Affiliation(s)
- Ming-Rui Li
- Department of Pharmacology, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, 410078, China
- Hunan Provincial Key Laboratory of Cardiovascular Research, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, 410078, China
| | - Xiu-Ju Luo
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, 410013, China.
| | - Jun Peng
- Department of Pharmacology, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, 410078, China.
- Hunan Provincial Key Laboratory of Cardiovascular Research, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, 410078, China.
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2
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Meng Z, Liang B, Wu Y, Liu C, Wang H, Du Y, Gan L, Gao E, Lau WB, Christopher TA, Lopez BL, Koch WJ, Ma X, Zhao F, Wang Y, Zhao J. Hypoadiponectinemia-induced upregulation of microRNA449b downregulating Nrf-1 aggravates cardiac ischemia-reperfusion injury in diabetic mice. J Mol Cell Cardiol 2023; 182:1-14. [PMID: 37437402 PMCID: PMC10566306 DOI: 10.1016/j.yjmcc.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 06/23/2023] [Accepted: 06/25/2023] [Indexed: 07/14/2023]
Abstract
Diabetes enhances myocardial ischemic/reperfusion (MI/R) injury via an incompletely understood mechanism. Adiponectin (APN) is a cardioprotective adipokine suppressed by diabetes. However, how hypoadiponectinemia exacerbates cardiac injury remains incompletely understood. Dysregulation of miRNAs plays a significant role in disease development. However, whether hypoadiponectinemia alters cardiac miRNA profile, contributing to diabetic heart injury, remains unclear. Methods and Results: Wild-type (WT) and APN knockout (APN-KO) mice were subjected to MI/R. A cardiac microRNA profile was determined. Among 23 miRNAs increased in APN-KO mice following MI/R, miR-449b was most significantly upregulated (3.98-fold over WT mice). Administrating miR-449b mimic increased apoptosis, enlarged infarct size, and impaired cardiac function in WT mice. In contrast, anti-miR-449b decreased apoptosis, reduced infarct size, and improved cardiac function in APN-KO mice. Bioinformatic analysis predicted 73 miR-449b targeting genes, and GO analysis revealed oxidative stress as the top pathway regulated by these genes. Venn analysis followed by luciferase assay identified Nrf-1 and Ucp3 as the two most important miR-449b targets. In vivo administration of anti-miR-449b in APN-KO mice attenuated MI/R-stimulated superoxide overproduction. In vitro experiments demonstrated that high glucose/high lipid and simulated ischemia/reperfusion upregulated miR-449b and inhibited Nrf-1 and Ucp3 expression. These pathological effects were attenuated by anti-miR-449b or Nrf-1 overexpression. In a final attempt to validate our finding in a clinically relevant model, high-fat diet (HFD)-induced diabetic mice were subjected to MI/R and treated with anti-miR-449b or APN. Diabetes significantly increased miR-449b expression and downregulated Nrf-1 and Ucp3 expression. Administration of anti-miR-449b or APN preserved cardiac Nrf-1 expression, reduced cardiac oxidative stress, decreased apoptosis and infarct size, and improved cardiac function. Conclusion: We demonstrated for the first time that hypoadiponectinemia upregulates miR-449b and suppresses Nrf-1/Ucp3 expression, promoting oxidative stress and exacerbating MI/R injury in this population. Dysregulated APN/miR-449b/oxidative stress pathway is a potential therapeutic target against diabetic MI/R injury.
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Affiliation(s)
- Zhijun Meng
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Bin Liang
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Yalin Wu
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294, United States of America
| | - Caihong Liu
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Han Wang
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Yunhui Du
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Lu Gan
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Erhe Gao
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140, United States of America
| | - Wayne B Lau
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Theodore A Christopher
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Bernard L Lopez
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Walter J Koch
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA 19140, United States of America
| | - Xinliang Ma
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America
| | - Fujie Zhao
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294, United States of America
| | - Yajing Wang
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, United States of America; Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294, United States of America.
| | - Jianli Zhao
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL 35294, United States of America.
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3
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Valizadeh A, Asghari S, Mansouri P, Alemi F, Majidinia M, Mahmoodpoor A, Yousefi B. The roles of signaling pathways in cardiac regeneration. Curr Med Chem 2021; 29:2142-2166. [PMID: 34521319 DOI: 10.2174/0929867328666210914115411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 07/05/2021] [Accepted: 07/20/2021] [Indexed: 11/22/2022]
Abstract
In recent years, knowledge of cardiac regeneration mechanisms has dramatically expanded. Regeneration can replace lost parts of organs, common among animal species. The heart is commonly considered an organ with terminal development, which has no reparability potential during post-natal life; however, some intrinsic regeneration capacity has been reported for cardiac muscle, which opens novel avenues in cardiovascular disease treatment. Different endogenous mechanisms were studied for cardiac repairing and regeneration in recent decades. Survival, proliferation, inflammation, angiogenesis, cell-cell communication, cardiomyogenesis, and anti-aging pathways are the most important mechanisms that have been studied in this regard. Several in vitro and animal model studies focused on proliferation induction for cardiac regeneration reported promising results. These studies have mainly focused on promoting proliferation signaling pathways and demonstrated various signaling pathways such as Wnt, PI3K/Akt, IGF-1, TGF-β, Hippo, and VEGF signaling cardiac regeneration. Therefore, in this review, we intended to discuss the connection between different critical signaling pathways in cardiac repair and regeneration.
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Affiliation(s)
- Amir Valizadeh
- Stem Cell and Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz. Iran
| | - Samira Asghari
- Stem Cell and Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz. Iran
| | - Parinaz Mansouri
- Students Research Center, Tabriz University of Medical Sciences, Tabriz. Iran
| | - Forough Alemi
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz. Iran
| | - Maryam Majidinia
- Solid Tumor Research Center, Urmia University of Medical Sciences, Urmia. Iran
| | - Ata Mahmoodpoor
- Stem Cell and Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz. Iran
| | - Bahman Yousefi
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz. Iran
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4
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Mellis D, Staines KA, Peluso S, Georgiou IC, Dora N, Kubiak M, van’t Hof R, Grillo M, Farquharson C, Kinsella E, Thornburn A, Ralston SH, Salter DM, Riobo-Del Galdo NA, Hill RE, Ditzel M. Ubiquitin-protein ligase Ubr5 cooperates with hedgehog signalling to promote skeletal tissue homeostasis. PLoS Genet 2021; 17:e1009275. [PMID: 33819267 PMCID: PMC8057592 DOI: 10.1371/journal.pgen.1009275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 04/20/2021] [Accepted: 03/20/2021] [Indexed: 12/11/2022] Open
Abstract
Mammalian Hedgehog (HH) signalling pathway plays an essential role in tissue homeostasis and its deregulation is linked to rheumatological disorders. UBR5 is the mammalian homologue of the E3 ubiquitin-protein ligase Hyd, a negative regulator of the Hh-pathway in Drosophila. To investigate a possible role of UBR5 in regulation of the musculoskeletal system through modulation of mammalian HH signaling, we created a mouse model for specific loss of Ubr5 function in limb bud mesenchyme. Our findings revealed a role for UBR5 in maintaining cartilage homeostasis and suppressing metaplasia. Ubr5 loss of function resulted in progressive and dramatic articular cartilage degradation, enlarged, abnormally shaped sesamoid bones and extensive heterotopic tissue metaplasia linked to calcification of tendons and ossification of synovium. Genetic suppression of smoothened (Smo), a key mediator of HH signalling, dramatically enhanced the Ubr5 mutant phenotype. Analysis of HH signalling in both mouse and cell model systems revealed that loss of Ubr5 stimulated canonical HH-signalling while also increasing PKA activity. In addition, human osteoarthritic samples revealed similar correlations between UBR5 expression, canonical HH signalling and PKA activity markers. Our studies identified a crucial function for the Ubr5 gene in the maintenance of skeletal tissue homeostasis and an unexpected mode of regulation of the HH signalling pathway.
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Affiliation(s)
- David Mellis
- Edinburgh CRUK Cancer Research Centre, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Katherine A. Staines
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Silvia Peluso
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Ioanna Ch. Georgiou
- Leeds Institute of Medical Research and School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Natalie Dora
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Malgorzata Kubiak
- Edinburgh CRUK Cancer Research Centre, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Rob van’t Hof
- Centre for Genomic and Experimental Medicine, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Michela Grillo
- Edinburgh CRUK Cancer Research Centre, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Colin Farquharson
- Roslin Institute and R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
| | - Elaine Kinsella
- Edinburgh CRUK Cancer Research Centre, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Anna Thornburn
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Stuart H. Ralston
- Centre for Genomic and Experimental Medicine, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Donald M. Salter
- Centre for Genomic and Experimental Medicine, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Natalia A. Riobo-Del Galdo
- Leeds Institute of Medical Research and School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Robert E. Hill
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Mark Ditzel
- Edinburgh CRUK Cancer Research Centre, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
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5
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Kopinke D, Norris AM, Mukhopadhyay S. Developmental and regenerative paradigms of cilia regulated hedgehog signaling. Semin Cell Dev Biol 2021; 110:89-103. [PMID: 32540122 PMCID: PMC7736055 DOI: 10.1016/j.semcdb.2020.05.029] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/25/2020] [Accepted: 05/29/2020] [Indexed: 01/08/2023]
Abstract
Primary cilia are immotile appendages that have evolved to receive and interpret a variety of different extracellular cues. Cilia play crucial roles in intercellular communication during development and defects in cilia affect multiple tissues accounting for a heterogeneous group of human diseases called ciliopathies. The Hedgehog (Hh) signaling pathway is one of these cues and displays a unique and symbiotic relationship with cilia. Not only does Hh signaling require cilia for its function but the majority of the Hh signaling machinery is physically located within the cilium-centrosome complex. More specifically, cilia are required for both repressing and activating Hh signaling by modifying bifunctional Gli transcription factors into repressors or activators. Defects in balancing, interpreting or establishing these repressor/activator gradients in Hh signaling either require cilia or phenocopy disruption of cilia. Here, we will summarize the current knowledge on how spatiotemporal control of the molecular machinery of the cilium allows for a tight control of basal repression and activation states of the Hh pathway. We will then discuss several paradigms on how cilia influence Hh pathway activity in tissue morphogenesis during development. Last, we will touch on how cilia and Hh signaling are being reactivated and repurposed during adult tissue regeneration. More specifically, we will focus on mesenchymal stem cells within the connective tissue and discuss the similarities and differences of how cilia and ciliary Hh signaling control the formation of fibrotic scar and adipose tissue during fatty fibrosis of several tissues.
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Affiliation(s)
- Daniel Kopinke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA.
| | - Alessandra M Norris
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
| | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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6
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Giarretta I, Gaetani E, Bigossi M, Tondi P, Asahara T, Pola R. The Hedgehog Signaling Pathway in Ischemic Tissues. Int J Mol Sci 2019; 20:ijms20215270. [PMID: 31652910 PMCID: PMC6862352 DOI: 10.3390/ijms20215270] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 10/22/2019] [Indexed: 12/19/2022] Open
Abstract
Hedgehog (Hh) proteins are prototypical morphogens known to regulate epithelial/mesenchymal interactions during embryonic development. In addition to its pivotal role in embryogenesis, the Hh signaling pathway may be recapitulated in post-natal life in a number of physiological and pathological conditions, including ischemia. This review highlights the involvement of Hh signaling in ischemic tissue regeneration and angiogenesis, with particular attention to the heart, the brain, and the skeletal muscle. Updated information on the potential role of the Hh pathway as a therapeutic target in the ischemic condition is also presented.
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Affiliation(s)
- Igor Giarretta
- Department of Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
| | - Eleonora Gaetani
- Department of Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
| | - Margherita Bigossi
- Department of Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
| | - Paolo Tondi
- Department of Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
| | - Takayuki Asahara
- Department of Regenerative Medicine Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.
| | - Roberto Pola
- Department of Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
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7
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de Oliveira PG, Ramos MLS, Amaro AJ, Dias RA, Vieira SI. G i/o-Protein Coupled Receptors in the Aging Brain. Front Aging Neurosci 2019; 11:89. [PMID: 31105551 PMCID: PMC6492497 DOI: 10.3389/fnagi.2019.00089] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/03/2019] [Indexed: 12/18/2022] Open
Abstract
Cells translate extracellular signals to regulate processes such as differentiation, metabolism and proliferation, via transmembranar receptors. G protein-coupled receptors (GPCRs) belong to the largest family of transmembrane receptors, with over 800 members in the human species. Given the variety of key physiological functions regulated by GPCRs, these are main targets of existing drugs. During normal aging, alterations in the expression and activity of GPCRs have been observed. The central nervous system (CNS) is particularly affected by these alterations, which results in decreased brain functions, impaired neuroregeneration, and increased vulnerability to neuropathologies, such as Alzheimer's and Parkinson diseases. GPCRs signal via heterotrimeric G proteins, such as Go, the most abundant heterotrimeric G protein in CNS. We here review age-induced effects of GPCR signaling via the Gi/o subfamily at the CNS. During the aging process, a reduction in protein density is observed for almost half of the Gi/o-coupled GPCRs, particularly in age-vulnerable regions such as the frontal cortex, hippocampus, substantia nigra and striatum. Gi/o levels also tend to decrease with aging, particularly in regions such as the frontal cortex. Alterations in the expression and activity of GPCRs and coupled G proteins result from altered proteostasis, peroxidation of membranar lipids and age-associated neuronal degeneration and death, and have impact on aging hallmarks and age-related neuropathologies. Further, due to oligomerization of GPCRs at the membrane and their cooperative signaling, down-regulation of a specific Gi/o-coupled GPCR may affect signaling and drug targeting of other types/subtypes of GPCRs with which it dimerizes. Gi/o-coupled GPCRs receptorsomes are thus the focus of more effective therapeutic drugs aiming to prevent or revert the decline in brain functions and increased risk of neuropathologies at advanced ages.
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Affiliation(s)
- Patrícia G de Oliveira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - Marta L S Ramos
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - António J Amaro
- School of Health Sciences (ESSUA), Universidade de Aveiro, Aveiro, Portugal
| | - Roberto A Dias
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
| | - Sandra I Vieira
- Department of Medical Sciences, Institute of Biomedicine (iBiMED) and The Discovery CTR, Universidade de Aveiro, Aveiro, Portugal
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8
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Yan Z, Guo R, Gan L, Lau WB, Cao X, Zhao J, Ma X, Christopher TA, Lopez BL, Wang Y. Withaferin A inhibits apoptosis via activated Akt-mediated inhibition of oxidative stress. Life Sci 2018; 211:91-101. [PMID: 30213729 DOI: 10.1016/j.lfs.2018.09.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/07/2018] [Accepted: 09/09/2018] [Indexed: 12/16/2022]
Abstract
Withaferin A (WFA), a withanolide derived from medicinal plant Withania somnifera, possesses anti-tumorigenic and immunomodulatory activities against various cancer cells. However, the role of WFA in myocardial ischemia reperfusion (MI/R) injury remains unclear. In the present study, we determined whether WFA may regulate cardiac ischemia reperfusion injury and elucidate the underlying mechanisms. We demonstrated that WFA enhanced H9c2 cells survival ability against simulated ischemia/reperfusion (SI/R) or hydrogen peroxide (H2O2)-induced cell apoptosis. In addition, the enhanced oxidative stress induced by SI/R was inhibited by WFA. Among the multiple antioxidant molecules determined, antioxidants SOD2, SOD3, Prdx-1 was obviously upregulated by WFA. When Akt inhibitor IV was administrated, WFA's suppression effect on oxidative stress was obviously abolished. Additional experiments demonstrated that WFA successfully inhibited H2O2 induced upregulation of SOD2, SOD3, and Prdx-1, ameliorated cardiomyocyte caspase-3 activity via an Akt dependent manner. Collectively, these results support the therapeutic potential of WFA against cardiac ischemia reperfusion injury and highlight the application of WFA in cardiovascular diseases holding great promise for the future.
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Affiliation(s)
- Zheyi Yan
- Department of Physiology, Shanxi Medical University, Shanxi, China; Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America; Department of Ophthalmology, The First Affiliated Hospital, Shanxi Medical University, Taiyuan, Shanxi, China
| | - Rui Guo
- Department of Physiology, Shanxi Medical University, Shanxi, China; Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Lu Gan
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Wayne Bond Lau
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Xiaoming Cao
- Department of Physiology, Shanxi Medical University, Shanxi, China
| | - Jianli Zhao
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Xinliang Ma
- Department of Physiology, Shanxi Medical University, Shanxi, China; Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Theodore A Christopher
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Bernard L Lopez
- Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Yajing Wang
- Department of Physiology, Shanxi Medical University, Shanxi, China; Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America.
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9
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Ho Wei L, Arastoo M, Georgiou I, Manning DR, Riobo-Del Galdo NA. Activation of the Gi protein-RHOA axis by non-canonical Hedgehog signaling is independent of primary cilia. PLoS One 2018; 13:e0203170. [PMID: 30148884 PMCID: PMC6110505 DOI: 10.1371/journal.pone.0203170] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/15/2018] [Indexed: 12/15/2022] Open
Abstract
Primary cilia are solitary organelles that emanate from the plasma membrane during growth arrest in almost all mammalian cells. The canonical Hedgehog (HH) pathway requires trafficking of the G protein-coupled receptor SMOOTHENED (SMO) and the GLI transcription factors to the primary cilium upon binding of a HH ligand to PATCHED1. However, it is unknown if activation of the small GTPase RHOA by SMO coupling to heterotrimeric Gi proteins, a form of non-canonical HH signaling, requires localization of SMO in the primary cilium. In this study, we compared RHOA and Gi protein stimulation by activation of SMO or sphingosine 1-phosphate receptor (S1P) receptors in WT and KIF3A-deficient mouse embryonic fibroblasts that lack primary cilia. We found that activation of SMO in response to Sonic HH (SHH) or purmorphamine (PUR), a small molecule agonist of SMO, stimulates Gi proteins and RHOA independently of the presence of primary cilia, similar to the effects of S1P. However, while S1P induced a fast activation of AKT that is sensitive to the Gi inhibitor pertussis toxin, HH pathway activators did not significantly activate AKT, suggesting that RHOA activation is not downstream of AKT. Our findings demonstrate that early events in some forms of non-canonical HH signaling occur in extraciliary membranes, which might be particularly relevant for actively-cycling cells, for some cancers characterized by loss of primary cilia, and in ciliopathies.
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Affiliation(s)
- Lan Ho Wei
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Mohammad Arastoo
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom
| | - Ioanna Georgiou
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom
| | - David R. Manning
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Natalia A. Riobo-Del Galdo
- Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- * E-mail:
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10
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Franco A, Zhang L, Matkovich SJ, Kovacs A, Dorn GW. G-protein receptor kinases 2, 5 and 6 redundantly modulate Smoothened-GATA transcriptional crosstalk in fetal mouse hearts. J Mol Cell Cardiol 2018; 121:60-68. [PMID: 29969579 PMCID: PMC6178805 DOI: 10.1016/j.yjmcc.2018.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 06/04/2018] [Accepted: 06/28/2018] [Indexed: 12/31/2022]
Abstract
G-protein receptor kinases (GRKs) regulate adult hearts by modulating inotropic, chronotropic and hypertrophic signaling of 7-transmembrane spanning neurohormone receptors. GRK-mediated desensitization and downregulation of β-adrenergic receptors has been implicated in adult heart failure; GRKs are therefore a promising therapeutic target. However, germ-line (but not cardiomyocyte-specific) GRK2 deletion provoked lethal fetal heart defects, suggesting an unexplained role for GRKs in heart development. Here we undertook to better understand the consequences of GRK deficiency on fetal heart development by creating mice and cultured murine embryonic fibroblasts (MEFs) having floxed GRK2 and GRK5 alleles on the GRK6 null background; simultaneous conditional deletion of these 3 GRK genes was achieved using Nkx2-5 Cre or adenoviral Cre, respectively. Phenotypes were related to GRK-modulated gene expression using whole-transcriptome RNA sequencing, RT-qPCR, and luciferase reporter assays. In cultured MEFs the atypical 7-transmembrane spanning protein and GRK2 substrate Smoothened (Smo) stimulated Gli-mediated transcriptional activity, which was interrupted by deleting GRK2/5/6. Mice with Nkx2-5 Cre mediated GRK2/5/6 ablation died between E15.5 and E16.5, whereas mice expressing any one of these 3 GRKs (i.e. GRK2/5, GRK2/6 or GRK5/6 deleted) were developmentally normal. GRK2/5/6 triple null mice at E14.5 exhibited left and right heart blood intermixing through single atrioventricular valves or large membranous ventricular septal defects. Hedgehog and GATA pathway gene expression promoted by Smo/Gli was suppressed in GRK2/5/6 deficient fetal hearts and MEFs. These data indicate that GRK2, GRK5 and GRK6 redundantly modulate Smo-GATA crosstalk in fetal mouse hearts, orchestrating transcriptional pathways previously linked to clinical and experimental atrioventricular canal defects. GRK modulation of Smo reflects convergence of conventional neurohormonal signaling and transcriptional regulation pathways, comprising an unanticipated mechanism for spatiotemporal orchestration of developmental gene expression in the heart.
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Affiliation(s)
- Antonietta Franco
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States.
| | - Lihong Zhang
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Scot J Matkovich
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Attila Kovacs
- Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States.
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11
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Praktiknjo SD, Saad F, Maier D, Ip P, Hipfner DR. Activation of Smoothened in the Hedgehog pathway unexpectedly increases Gα s-dependent cAMP levels in Drosophila. J Biol Chem 2018; 293:13496-13508. [PMID: 30018136 DOI: 10.1074/jbc.ra118.001953] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 07/13/2018] [Indexed: 12/28/2022] Open
Abstract
Hedgehog (Hh) signaling plays a key role in the development and maintenance of animal tissues. This signaling is mediated by the atypical G protein-coupled receptor (GPCR) Smoothened (Smo). Smo activation leads to signaling through several well-characterized effectors to activate Hh target gene expression. Recent studies have implicated activation of the heterotrimeric G protein subunit Gαi and the subsequent decrease in cellular cAMP levels in promoting the Hh response in flies and mammals. Although Hh stimulation decreases cAMP levels in some insect cell lines, here using a bioluminescence resonance energy transfer (BRET)-based assay we found that this stimulation had no detectable effect in Drosophila S2-R+ cells. However, we observed an unexpected and significant Gαs-dependent increase in cAMP levels in response to strong Smo activation in Smo-transfected cells. This effect was mediated by Smo's broadly conserved core, and was specifically activated in response to phosphorylation of the Smo C-terminus by GPCR kinase 2 (Gprk2). Genetic analysis of heterotrimeric G protein function in the developing Drosophila wing revealed a positive role for cAMP in the endogenous Hh response. Specifically, we found that mutation or depletion of Gαs diminished low-threshold Hh responses in Drosophila, whereas depletion of Gαi potentiated them (in contrast to previous findings). Our analysis suggested that regulated cAMP production is important for controlling the sensitivity of cellular responses to Hh in Drosophila.
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Affiliation(s)
- Samantha D Praktiknjo
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - Farah Saad
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,Biology, McGill University, Montreal, Quebec H3A 0C7, and
| | - Dominic Maier
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - Pamela Ip
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7.,the Departments of Anatomy and Cell Biology and
| | - David R Hipfner
- From the Institut de recherches cliniques de Montréal, Montreal, Quebec H2W 1R7, .,the Departments of Anatomy and Cell Biology and.,Biology, McGill University, Montreal, Quebec H3A 0C7, and.,the Département de médecine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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12
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Cheng L, Al-Owais M, Covarrubias ML, Koch WJ, Manning DR, Peers C, Riobo-Del Galdo NA. Coupling of Smoothened to inhibitory G proteins reduces voltage-gated K + currents in cardiomyocytes and prolongs cardiac action potential duration. J Biol Chem 2018; 293:11022-11032. [PMID: 29802197 DOI: 10.1074/jbc.ra118.001989] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 05/10/2018] [Indexed: 12/25/2022] Open
Abstract
SMO (Smoothened), the central transducer of Hedgehog signaling, is coupled to heterotrimeric Gi proteins in many cell types, including cardiomyocytes. In this study, we report that activation of SMO with SHH (Sonic Hedgehog) or a small agonist, purmorphamine, rapidly causes a prolongation of the action potential duration that is sensitive to a SMO inhibitor. In contrast, neither of the SMO agonists prolonged the action potential in cardiomyocytes from transgenic GiCT/TTA mice, in which Gi signaling is impaired, suggesting that the effect of SMO is mediated by Gi proteins. Investigation of the mechanism underlying the change in action potential kinetics revealed that activation of SMO selectively reduces outward voltage-gated K+ repolarizing (Kv) currents in isolated cardiomyocytes and that it induces a down-regulation of membrane levels of Kv4.3 in cardiomyocytes and intact hearts from WT but not from GiCT/TTA mice. Moreover, perfusion of intact hearts with Shh or purmorphamine increased the ventricular repolarization time (QT interval) and induced ventricular arrhythmias. Our data constitute the first report that acute, noncanonical Hh signaling mediated by Gi proteins regulates K+ currents density in cardiomyocytes and sensitizes the heart to the development of ventricular arrhythmias.
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Affiliation(s)
- Lan Cheng
- From the Departments of Biochemistry & Molecular Biology and
| | - Moza Al-Owais
- the Leeds Institute of Cardiovascular and Metabolic Medicine and
| | | | - Walter J Koch
- the Department of Pharmacology and Center for Translational Medicine, Temple University, Philadelphia, Pennsylvania 19140, and
| | - David R Manning
- the Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Chris Peers
- the Leeds Institute of Cardiovascular and Metabolic Medicine and
| | - Natalia A Riobo-Del Galdo
- From the Departments of Biochemistry & Molecular Biology and .,the Leeds Institute of Cancer and Pathology, School of Medicine, University of Leeds, Leeds LS2 9JT, United Kingdom
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13
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Rao R, Salloum R, Xin M, Lu QR. The G protein Gαs acts as a tumor suppressor in sonic hedgehog signaling-driven tumorigenesis. Cell Cycle 2018; 15:1325-30. [PMID: 27052725 DOI: 10.1080/15384101.2016.1164371] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are critical players in tumor growth and progression. The redundant roles of GPCRs in tumor development confound effective treatment; therefore, targeting a single common signaling component downstream of these receptors may be efficacious. GPCRs transmit signals through heterotrimeric G proteins composed of Gα and Gβγ subunits. Hyperactive Gαs signaling can mediate tumor progression in some tissues; however, recent work in medulloblastoma and basal cell carcinoma revealed that Gαs can also function as a tumor suppressor in neoplasms derived from ectoderm cells including neural and epidermal stem/progenitor cells. In these stem-cell compartments, signaling through Gαs suppresses self-renewal by inhibiting the Sonic Hedgehog (SHH) and Hippo pathways. The loss of GNAS, which encodes Gαs, leads to activation of these pathways, over-proliferation of progenitor cells, and tumor formation. Gαs activates the cAMP-dependent protein kinase A (PKA) signaling pathway and inhibits activation of SHH effectors Smoothened-Gli. In addition, Gαs-cAMP-PKA activation negatively regulates the Hippo pathway by blocking the NF2-LATS1/2-Yap signaling. In this review, we will address the novel function of the signaling network regulated by Gαs in suppression of SHH-driven tumorigenesis and the therapeutic approaches that can be envisioned to harness this pathway to inhibit tumor growth and progression.
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Affiliation(s)
- Rohit Rao
- a University of Cincinnati Medical Scientist Training Program , Cincinnati , OH , USA
| | - Ralph Salloum
- b Brain Tumor Center, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center , Cincinnati , OH , USA
| | - Mei Xin
- b Brain Tumor Center, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center , Cincinnati , OH , USA
| | - Q Richard Lu
- b Brain Tumor Center, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center , Cincinnati , OH , USA
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14
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Henno P, Grassin-Delyle S, Belle E, Brollo M, Naline E, Sage E, Devillier P, Israël-Biet D. In smokers, Sonic hedgehog modulates pulmonary endothelial function through vascular endothelial growth factor. Respir Res 2017; 18:102. [PMID: 28535764 PMCID: PMC5442874 DOI: 10.1186/s12931-017-0590-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/17/2017] [Indexed: 02/06/2023] Open
Abstract
Background Tobacco-induced pulmonary vascular disease is partly driven by endothelial dysfunction. The Sonic hedgehog (SHH) pathway is involved in vascular physiology. We sought to establish whether the SHH pathway has a role in pulmonary endothelial dysfunction in smokers. Methods The ex vivo endothelium-dependent relaxation of pulmonary artery rings in response to acetylcholine (Ach) was compared in 34 current or ex-smokers and 8 never-smokers. The results were expressed as a percentage of the contraction with phenylephrine. We tested the effects of SHH inhibitors (GANT61 and cyclopamine), an SHH activator (SAG) and recombinant VEGF on the Ach-induced relaxation. The level of VEGF protein in the pulmonary artery ring was measured in an ELISA. SHH pathway gene expression was quantified in reverse transcriptase–quantitative polymerase chain reactions. Results Ach-induced relaxation was much less intense in smokers than in never-smokers (respectively 24 ± 6% and 50 ± 7% with 10−4M Ach; p = 0.028). All SHH pathway genes were expressed in pulmonary artery rings from smokers. SHH inhibition by GANT61 reduced Ach-induced relaxation and VEGF gene expression in the pulmonary artery ring. Recombinant VEGF restored the ring’s endothelial function. VEGF gene and protein expression levels in the pulmonary artery rings were positively correlated with the degree of Ach-induced relaxation and negatively correlated with the number of pack-years. Conclusion SHH pathway genes and proteins are expressed in pulmonary artery rings from smokers, where they modulate endothelial function through VEGF.
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Affiliation(s)
- Priscilla Henno
- Sorbonne Paris Cité, Université Paris-Descartes, Paris, France. .,AP-HP, Hôpital Européen Georges Pompidou, Service de Physiologie, Explorations Fonctionnelles Respiratoires et du Sommeil, 75015, Paris, France. .,UPRES EA220, Université Versailles Saint-Quentin, Université Paris-Saclay, F-92150, Suresnes, France.
| | - Stanislas Grassin-Delyle
- Plateforme de Spectrométrie de Masse & INSERM UMR1173, UFR Sciences de la Santé Simone Veil, Université Versailles Saint Quentin, Université Paris-Saclay, 78180, Montigny-le-Bretonneux, France.,Département des Maladies des Voies Respiratoires, Hôpital Foch, F-92150, Suresnes, France
| | - Emeline Belle
- UPRES EA220, Université Versailles Saint-Quentin, Université Paris-Saclay, F-92150, Suresnes, France
| | - Marion Brollo
- UPRES EA220, Université Versailles Saint-Quentin, Université Paris-Saclay, F-92150, Suresnes, France
| | - Emmanuel Naline
- UPRES EA220, Université Versailles Saint-Quentin, Université Paris-Saclay, F-92150, Suresnes, France.,Département des Maladies des Voies Respiratoires, Hôpital Foch, F-92150, Suresnes, France
| | - Edouard Sage
- Service de Chirurgie Thoracique, Département des Maladies des Voies Respiratoires, Hôpital Foch, F-92150, Suresnes, France
| | - Philippe Devillier
- UPRES EA220, Université Versailles Saint-Quentin, Université Paris-Saclay, F-92150, Suresnes, France.,Département des Maladies des Voies Respiratoires, Hôpital Foch, F-92150, Suresnes, France
| | - Dominique Israël-Biet
- Sorbonne Paris Cité, Université Paris-Descartes, Paris, France.,AP-HP; Hôpital Européen Georges Pompidou, Service de Pneumologie, 75015, Paris, France
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15
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Hh signaling in regeneration of the ischemic heart. Cell Mol Life Sci 2017; 74:3481-3490. [PMID: 28523343 PMCID: PMC5589787 DOI: 10.1007/s00018-017-2534-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 04/10/2017] [Accepted: 05/02/2017] [Indexed: 12/23/2022]
Abstract
Myocardial infarction (MI) is caused by the occlusion of a coronary artery due to underlying atherosclerosis complicated by localized thrombosis. The blockage of blood flow leads to cardiomyocyte (CM) death in the infarcted area. Adult mammalian cardiomyocytes have little capacity to proliferate in response to injury; however, some pathways active during embryogenesis and silent during adult life are recruited in response to tissue injury. One such example is hedgehog (Hh) signaling. Hh is involved in the embryonic development of the heart and coronary vascular system. Pathological conditions including ischemia activate Hh signaling in adult tissues. This review highlights the involvement of Hh signaling in ischemic tissue regeneration with a particular emphasis on heart regeneration and discusses its potential role as a therapeutic agent.
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16
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Arensdorf AM, Marada S, Ogden SK. Smoothened Regulation: A Tale of Two Signals. Trends Pharmacol Sci 2015; 37:62-72. [PMID: 26432668 DOI: 10.1016/j.tips.2015.09.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 02/09/2023]
Abstract
The G protein-coupled receptor (GPCR) Smoothened (Smo) is the signal transducer of the developmentally and therapeutically relevant Hedgehog (Hh) pathway. Although recent structural analyses have advanced our understanding of Smo biology, several questions remain. Chief among them are the identity of its natural ligand, the regulatory processes controlling its activation, and the mechanisms by which it signals to downstream effectors. In this review, we discuss recent discoveries from multiple model systems that have set the stage for solving these mysteries. We focus on the roles of distinct Smo functional domains, post-translational modifications, and trafficking, and conclude by discussing their contributions to signal output.
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Affiliation(s)
- Angela M Arensdorf
- Department of Cell and Molecular Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place MS#340, Memphis, TN 38105, USA
| | - Suresh Marada
- Department of Cell and Molecular Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place MS#340, Memphis, TN 38105, USA
| | - Stacey K Ogden
- Department of Cell and Molecular Biology, St Jude Children's Research Hospital, 262 Danny Thomas Place MS#340, Memphis, TN 38105, USA.
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17
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McCabe JM, Leahy DJ. Smoothened goes molecular: new pieces in the hedgehog signaling puzzle. J Biol Chem 2014; 290:3500-7. [PMID: 25519909 DOI: 10.1074/jbc.r114.617936] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A general aim of studies of signal transduction is to identify mediators of specific signals, order them into pathways, and understand the nature of interactions between individual components and how these interactions alter pathway behavior. Despite years of intensive study and its central importance to animal development and human health, our understanding of the Hedgehog (Hh) signaling pathway remains riddled with gaps, question marks, assumptions, and poorly understood connections. In particular, understanding how interactions between Hh and Patched (Ptc), a 12-pass integral membrane protein, lead to modulation of the function of Smoothened (Smo), a 7-pass integral membrane protein, has defied standard biochemical characterization. Recent structural and biochemical characterizations of Smoothened domains have begun to unlock this riddle, however, and lay the groundwork for improved cancer therapies.
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Affiliation(s)
- Jacqueline M McCabe
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Daniel J Leahy
- From the Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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