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Singh J, Wen X, Scales SJ. The Orphan G Protein-coupled Receptor Gpr175 (Tpra40) Enhances Hedgehog Signaling by Modulating cAMP Levels. J Biol Chem 2015; 290:29663-75. [PMID: 26451044 DOI: 10.1074/jbc.m115.665810] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 11/06/2022] Open
Abstract
The Hedgehog (Hh) signaling pathway plays an essential role in vertebrate embryonic tissue patterning of many developing organs. Signaling occurs predominantly in primary cilia and is initiated by the entry of the G protein-coupled receptor (GPCR)-like protein Smoothened into cilia and culminates in gene transcription via the Gli family of transcription factors upon their nuclear entry. Here we identify an orphan GPCR, Gpr175 (also known as Tpra1 or Tpra40: transmembrane protein, adipocyte associated 1 or of 40 kDa), which also localizes to primary cilia upon Hh stimulation and positively regulates Hh signaling. Interaction experiments place Gpr175 at the level of PKA and upstream of the Gαi component of heterotrimeric G proteins, which itself localizes to cilia and can modulate Hh signaling. Gpr175 or Gαi1 depletion leads to increases in cellular cAMP levels and in Gli3 processing into its repressor form. Thus we propose that Gpr175 coupled to Gαi1 normally functions to inhibit the production of cAMP by adenylyl cyclase upon Hh stimulation, thus maximizing signaling by turning off PKA activity and hence Gli3 repressor formation. Taken together our data suggest that Gpr175 is a novel positive regulator of the Hh signaling pathway.
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Affiliation(s)
- Jaskirat Singh
- From the Department of Molecular Biology, Genentech, South San Francisco, California 94080
| | - Xiaohui Wen
- From the Department of Molecular Biology, Genentech, South San Francisco, California 94080
| | - Suzie J Scales
- From the Department of Molecular Biology, Genentech, South San Francisco, California 94080
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Villanueva H, Visbal AP, Obeid NF, Ta AQ, Faruki AA, Wu MF, Hilsenbeck SG, Shaw CA, Yu P, Plummer NW, Birnbaumer L, Lewis MT. An essential role for Gα(i2) in Smoothened-stimulated epithelial cell proliferation in the mammary gland. Sci Signal 2015; 8:ra92. [PMID: 26373672 DOI: 10.1126/scisignal.aaa7355] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. The gene encoding Smoothened (SMO), the primary effector of Hh signaling, is expressed aberrantly in human breast cancer, as well as in other cancers. In mice that express a constitutively active form of SMO that does not require Hh stimulation in mammary glands, the cells near the transgenic cells proliferate and participate in hyperplasia formation. Although SMO is a seven-transmembrane receptor like G protein-coupled receptors (GPCRs), SMO-mediated activation of the Gli family of transcription factors is not known to involve G proteins. However, data from Drosophila and mammalian cell lines indicate that SMO functions as a GPCR that couples to heterotrimeric G proteins of the pertussis toxin (PTX)-sensitive Gαi class. Using genetically modified mice, we demonstrated that SMO signaling through G proteins occurred in the mammary gland in vivo. SMO-induced stimulation of proliferation was PTX-sensitive and required Gαi2, but not Gαi1, Gαi3, or activation of Gli1 or Gli2. Our findings show that activated SMO functions as a GPCR to stimulate proliferation in vivo, a finding that may have clinical importance because most SMO-targeted agents have been selected based largely on their ability to block Gli-mediated transcription.
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Affiliation(s)
- Hugo Villanueva
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adriana P Visbal
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nadine F Obeid
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrew Q Ta
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adeel A Faruki
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng-Fen Wu
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Susan G Hilsenbeck
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA. Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chad A Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Peng Yu
- Department of Electrical and Computer Engineering, TEES-AgriLife Center for Bioinformatics and Genomic Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Nicholas W Plummer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Michael T Lewis
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA. Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA. Department of Radiology, Baylor College of Medicine, Houston, TX 77030, USA.
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Marada S, Navarro G, Truong A, Stewart DP, Arensdorf AM, Nachtergaele S, Angelats E, Opferman JT, Rohatgi R, McCormick PJ, Ogden SK. Functional Divergence in the Role of N-Linked Glycosylation in Smoothened Signaling. PLoS Genet 2015; 11:e1005473. [PMID: 26291458 PMCID: PMC4546403 DOI: 10.1371/journal.pgen.1005473] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/28/2015] [Indexed: 01/06/2023] Open
Abstract
The G protein-coupled receptor (GPCR) Smoothened (Smo) is the requisite signal transducer of the evolutionarily conserved Hedgehog (Hh) pathway. Although aspects of Smo signaling are conserved from Drosophila to vertebrates, significant differences have evolved. These include changes in its active sub-cellular localization, and the ability of vertebrate Smo to induce distinct G protein-dependent and independent signals in response to ligand. Whereas the canonical Smo signal to Gli transcriptional effectors occurs in a G protein-independent manner, its non-canonical signal employs Gαi. Whether vertebrate Smo can selectively bias its signal between these routes is not yet known. N-linked glycosylation is a post-translational modification that can influence GPCR trafficking, ligand responsiveness and signal output. Smo proteins in Drosophila and vertebrate systems harbor N-linked glycans, but their role in Smo signaling has not been established. Herein, we present a comprehensive analysis of Drosophila and murine Smo glycosylation that supports a functional divergence in the contribution of N-linked glycans to signaling. Of the seven predicted glycan acceptor sites in Drosophila Smo, one is essential. Loss of N-glycosylation at this site disrupted Smo trafficking and attenuated its signaling capability. In stark contrast, we found that all four predicted N-glycosylation sites on murine Smo were dispensable for proper trafficking, agonist binding and canonical signal induction. However, the under-glycosylated protein was compromised in its ability to induce a non-canonical signal through Gαi, providing for the first time evidence that Smo can bias its signal and that a post-translational modification can impact this process. As such, we postulate a profound shift in N-glycan function from affecting Smo ER exit in flies to influencing its signal output in mice. N-linked glycosylation is a post-translational modification occurring on membrane proteins such as G protein-coupled receptors (GPCR). Smoothened (Smo) is a GPCR that functions as the signal transducer of the Hedgehog (Hh) pathway. We used a mutagenesis approach to assess the role of N-glycans in Smo signaling in two genetic models for Hh pathway activity, Drosophila and mouse. In doing so, we discovered a divergence in glycan function between them. We mapped an essential N-glycan acceptor site that when lost in Drosophila, triggered ER retention, altered Smo protein stability and blunted its signaling capacity. Conversely, ER exit of the murine protein was unaffected by glycan loss, as was its ability to traffic and induce a G protein-independent signal to activate Hh target genes. However, the ability of vertebrate Smo to induce a distinct G protein-dependent signal was lost. This suggests that N-linked glycosylation may influence signal bias of vertebrate Smo to favor one signal output over the other. We therefore propose that the role of this conserved post-translational modification may have been repurposed from governing Smo ER exit in the fly to influencing effector route selection in vertebrates.
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Affiliation(s)
- Suresh Marada
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Gemma Navarro
- Department of Biochemistry and Molecular Biology, Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)University of Barcelona, Barcelona, Spain
| | - Ashley Truong
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
- Summer Plus Program, Rhodes College, Memphis, Tennessee, United States of America
| | - Daniel P. Stewart
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Angela M. Arensdorf
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Sigrid Nachtergaele
- Departments of Medicine and Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Edgar Angelats
- Department of Biochemistry and Molecular Biology, Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)University of Barcelona, Barcelona, Spain
| | - Joseph T. Opferman
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Rajat Rohatgi
- Departments of Medicine and Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Peter J. McCormick
- Department of Biochemistry and Molecular Biology, Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)University of Barcelona, Barcelona, Spain
- School of Pharmacy, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - Stacey K. Ogden
- Department of Cell & Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
- * E-mail:
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Expression Profile of Sonic Hedgehog Pathway Members in the Developing Human Fetal Brain. BIOMED RESEARCH INTERNATIONAL 2015; 2015:494269. [PMID: 26266257 PMCID: PMC4523658 DOI: 10.1155/2015/494269] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 03/29/2015] [Accepted: 03/30/2015] [Indexed: 11/17/2022]
Abstract
The Sonic Hedgehog (SHH) pathway plays a central role in the developing mammalian CNS. In our study, we aimed to investigate the spatiotemporal SHH pathway expression pattern in human fetal brains. We analyzed 22 normal fetal brains for Shh, Patched, Smoothened, and Gli1-3 expression by immunohistochemistry. In the telencephalon, strongest expression of Shh, Smoothened, and Gli2 was found in the cortical plate (CP) and ventricular zone. Patched was strongly upregulated in the ventricular zone and Gli1 in the CP. In the cerebellum, SHH pathway members were strongly expressed in the external granular layer (EGL). SHH pathway members significantly decreased over time in the ventricular and subventricular zone and in the cerebellar EGL, while increasing levels were found in more superficial telencephalic layers. Our findings show that SHH pathway members are strongly expressed in areas important for proliferation and differentiation and indicate a temporal expression gradient in telencephalic and cerebellar layers probably due to decreased proliferation of progenitor cells and increased differentiation. Our data about the spatiotemporal expression of SHH pathway members in the developing human brain serves as a base for the understanding of both normal and pathological CNS development.
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55
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Regulation of the oncoprotein Smoothened by small molecules. Nat Chem Biol 2015; 11:246-55. [PMID: 25785427 DOI: 10.1038/nchembio.1776] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/19/2015] [Indexed: 01/01/2023]
Abstract
The Hedgehog pathway is critical for animal development and has been implicated in multiple human malignancies. Despite great interest in targeting the pathway pharmacologically, many of the principles underlying the signal transduction cascade remain poorly understood. Hedgehog ligands are recognized by a unique receptor system that features the transporter-like protein Patched and the G protein-coupled receptor (GPCR)-like Smoothened (SMO). The biochemical interaction between these transmembrane proteins is the subject of intensive efforts. Recent structural and functional studies have provided great insight into the small-molecule regulation of SMO through identification of two distinct ligand-binding sites. In this Perspective, we review these recent findings and relate them to potential mechanisms for the endogenous regulation of SMO.
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Molecular signalling in hepatocellular carcinoma: Role of and crosstalk among WNT/ß-catenin, Sonic Hedgehog, Notch and Dickkopf-1. Can J Gastroenterol Hepatol 2015; 29:209-17. [PMID: 25965442 PMCID: PMC4444031 DOI: 10.1155/2015/172356] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma is the sixth most common cancer worldwide. In the majority of cases, there is evidence of existing chronic liver disease from a variety of causes including viral hepatitis B and C, alcoholic liver disease and nonalcoholic steatohepatitis. Identification of the signalling pathways used by hepatocellular carcinoma cells to proliferate, invade or metastasize is of paramount importance in the discovery and implementation of successfully targeted therapies. Activation of Wnt/β-catenin, Notch and Hedgehog pathways play a critical role in regulating liver cell proliferation during development and in controlling crucial functions of the adult liver in the initiation and progression of human cancers. β-catenin was identified as a protein interacting with the cell adhesion molecule E-cadherin at the cell-cell junction, and has been shown to be one of the most important mediators of the Wnt signalling pathway in tumourigenesis. Investigations into the role of Dikkopf-1 in hepatocellular carcinoma have demonstrated controversial results, with a decreased expression of Dickkopf-1 and soluble frizzled-related protein in various cancers on one hand, and as a possible negative prognostic indicator of hepatocellular carcinoma on the other. In the present review, the authors focus on the Wnt⁄β-catenin, Notch and Sonic Hedgehog pathways, and their interaction with Dikkopf-1 in hepatocellular carcinoma.
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Early steps in primary cilium assembly require EHD1/EHD3-dependent ciliary vesicle formation. Nat Cell Biol 2015; 17:228-240. [PMID: 25686250 PMCID: PMC4344897 DOI: 10.1038/ncb3109] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 01/13/2015] [Indexed: 12/12/2022]
Abstract
Membrane association with mother centriole (M-centriole) distal appendages is critical for ciliogenesis initiation. How the Rab GTPase Rab11-Rab8 cascade functions in early ciliary membrane assembly is unknown. Here, we show that the membrane shaping proteins EHD1 and EHD3, in association with the Rab11-Rab8 cascade, function in early ciliogenesis. EHD1 and EHD3 localize to pre-ciliary membranes and the ciliary pocket. EHD-dependent membrane tubulation is essential for ciliary vesicle (CV) formation from smaller distal appendage vesicles (DAV). Importantly, this step functions in M-centriole to basal body transformation and recruitment of transition zone proteins and IFT20. SNAP29, a SNARE membrane fusion regulator and EHD1-binding protein, is also required for DAV-mediated CV assembly. Interestingly, only after CV assembly is Rab8 activated for ciliary growth. Our studies uncover molecular mechanisms informing a previously uncharacterized ciliogenesis step whereby EHD1 and EHD3 reorganize the M-centriole and associated DAV prior to coordinated ciliary membrane and axoneme growth.
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Ferraro S, Gomez-Montalvo AI, Olmos R, Ramirez M, Lamas M. Primary cilia in rat mature Müller glia: downregulation of IFT20 expression reduces sonic hedgehog-mediated proliferation and dedifferentiation potential of Müller glia primary cultures. Cell Mol Neurobiol 2014; 35:533-42. [PMID: 25504432 DOI: 10.1007/s10571-014-0149-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/08/2014] [Indexed: 11/26/2022]
Abstract
Primary cilia are specialized organelles that extend from the cell surface and concentrate signal transduction components. In the nervous system, primary cilia-associated signals, such as sonic hedgehog (Shh), regulate cell proliferation and neuronal fate. Primary cilia assembly and maintenance require a multi-subunit intraflagellar transport (IFT) protein complex. Defects in primary cilia and IFT proteins are associated to severe pathological phenotypes. In the retina, the study of primary cilia has been mainly restricted to the specialized photoreceptor outer segment. The presence and physiological role of primary cilia in other retinal cells have not been clearly elucidated. Müller cells are the main glia of the retina where they exert distinct functions to maintain homeostasis. In pathological conditions, Müller cells mount a unique regenerative response through the processes of dedifferentiation, proliferation, and differentiation into neuronal lineages. The involvement of IFT proteins or a primary cilium in these processes has not been explored. In this study, we used mature Müller glia primary cultures to reveal the presence of the primary cilia by immunoreactivity to acetylated α-tubulin and γ-tubulin, which localize to the axoneme and ciliar basal body, respectively. We demonstrate that si-RNA-mediated downregulation of IFT20 gene expression, a main component of the IFT machinery, blocks Shh-induced Müller cell proliferation. We present evidence that IFT20 ablation impairs the dedifferentiation capacity of Müller cells induced by Shh and by glutamate. Our demonstration that Müller glia expresses IFT20 and harbors primary cilia, and opens new venues of research on the role of primary cilia in the retina.
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Affiliation(s)
- Silene Ferraro
- Departamento de Farmacobiología, CINVESTAV Sede Sur, Calzada de los Tenorios 235, Mexico, DF, Mexico
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JIN DANJUAN, FANG YANTIAN, LI ZHENGYANG, CHEN ZONGYOU, XIANG JIANBIN. Epithelial-mesenchymal transition-associated microRNAs in colorectal cancer and drug-targeted therapies (Review). Oncol Rep 2014; 33:515-25. [DOI: 10.3892/or.2014.3638] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 11/17/2014] [Indexed: 11/06/2022] Open
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Hu L, Lin X, Lu H, Chen B, Bai Y. An overview of hedgehog signaling in fibrosis. Mol Pharmacol 2014; 87:174-82. [PMID: 25395043 DOI: 10.1124/mol.114.095141] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Hedgehog (Hh) signaling pathway plays a key role during embryogenesis and tissue regeneration. Recently, studies revealed that overactivated Hh signaling leads to fibrogenesis in many types of tissues. The activation of Hh signaling is involved in the epithelial-mesenchymal transition and excessive extracellular matrix deposition. Blockade of Hh signaling abolishes the induction of the epithelial-mesenchymal transition and ameliorates tissue fibrosis. Therefore, new therapeutic targets to alleviate fibrosis based on the Hh signaling have attracted a great deal of attention. This is a new strategy for treating fibrosis and other related diseases. In this review, we discuss the crucial role of Hh signaling in fibrogenesis to provide a better understanding of their relationship and to encourage the study of novel targeted therapies.
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Affiliation(s)
- Liping Hu
- Department of Laboratory Medicine, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (L.H., X.L., H.L.); Department of Laboratory Medicine, JianLi County People's Hospital, Jingzhou (L.H.); and Wenzhou Key Laboratory of Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (B.C., Y.B.), People's Republic of China
| | - Xiangyang Lin
- Department of Laboratory Medicine, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (L.H., X.L., H.L.); Department of Laboratory Medicine, JianLi County People's Hospital, Jingzhou (L.H.); and Wenzhou Key Laboratory of Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (B.C., Y.B.), People's Republic of China
| | - Hong Lu
- Department of Laboratory Medicine, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (L.H., X.L., H.L.); Department of Laboratory Medicine, JianLi County People's Hospital, Jingzhou (L.H.); and Wenzhou Key Laboratory of Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (B.C., Y.B.), People's Republic of China
| | - Bicheng Chen
- Department of Laboratory Medicine, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (L.H., X.L., H.L.); Department of Laboratory Medicine, JianLi County People's Hospital, Jingzhou (L.H.); and Wenzhou Key Laboratory of Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (B.C., Y.B.), People's Republic of China
| | - Yongheng Bai
- Department of Laboratory Medicine, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (L.H., X.L., H.L.); Department of Laboratory Medicine, JianLi County People's Hospital, Jingzhou (L.H.); and Wenzhou Key Laboratory of Surgery, First Affiliated Hospital, Wenzhou Medical University, Wenzhou (B.C., Y.B.), People's Republic of China
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Choe JY, Yun JY, Jeon YK, Kim SH, Choung HK, Oh S, Park M, Kim JE. Sonic hedgehog signalling proteins are frequently expressed in retinoblastoma and are associated with aggressive clinicopathological features. J Clin Pathol 2014; 68:6-11. [PMID: 25296932 DOI: 10.1136/jclinpath-2014-202434] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS This study aimed to examine the expression of Sonic hedgehog (SHH) signalling proteins in retinoblastoma and to evaluate its clinical significance. METHODS Seventy-nine enucleated retinoblastoma tumours were investigated immunohistochemically using antibodies against SHH pathway proteins, such as SHH, glioma-associated oncogene homologue (GLI) 1, GLI2, GLI3 and ABC binding cassette G2 (ABCG2). Western blotting of SHH signalling proteins was performed in two retinoblastoma cell lines. RESULTS SHH was expressed in most retinoblastoma cases (78 of 79, 98.7%), with 21 cases (26.6%) showing strong expression. GLI1 and GLI2 were also frequently expressed: 67 of 78 cases (85.9%) and 71 of 77 cases (92.2%), respectively. GLI3, a transcriptional repressor, was expressed at low levels in 23 of the 78 cases (29.5%). High ABCG2 expression was found in 23 of the 78 cases (29.5%). High expression levels of these proteins in retinoblastoma cell lines were confirmed by western blotting. The expression of SHH was associated with advanced stages, local invasion and metastasis (all p<0.05). CONCLUSIONS SHH signalling molecules were frequently expressed in retinoblastoma tumour cells, and high SHH expression was closely related to an advanced disease status. Our results suggest that the SHH signalling pathway may play a role in the progression of retinoblastoma.
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Affiliation(s)
- Ji-Young Choe
- Department of Pathology, Seoul National University, College of Medicine, Seoul, Korea Department of Pathology, Seoul National University Bundang Hospital, Gyeonggi-Do, Korea
| | - Ji Yun Yun
- Department of Pathology, Seoul National University, College of Medicine, Seoul, Korea Department of Pathology, Seoul National University Bundang Hospital, Gyeonggi-Do, Korea
| | - Yoon Kyung Jeon
- Department of Pathology, Seoul National University, College of Medicine, Seoul, Korea Department of Pathology, Seoul National University Hospital, Seoul, Korea
| | - Se Hoon Kim
- Department of Pathology, Yonsei Unversity, College of Medicine, Seoul, Korea
| | - Ho-Kyung Choung
- Department of Ophthalmology, Seoul National University Boramae Hospital, Seoul, Korea
| | - Sohee Oh
- Department of Biostatistics, Seoul National University Boramae Hospital, Seoul, Korea
| | - Mira Park
- Department of Pathology, Seoul National University Boramae Hospital, Seoul, Korea
| | - Ji Eun Kim
- Department of Pathology, Seoul National University, College of Medicine, Seoul, Korea Department of Pathology, Seoul National University Boramae Hospital, Seoul, Korea
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Kraft S, Granter SR. Molecular pathology of skin neoplasms of the head and neck. Arch Pathol Lab Med 2014; 138:759-87. [PMID: 24878016 DOI: 10.5858/arpa.2013-0157-ra] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region. OBJECTIVE To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations. DATA SOURCES Literature review. CONCLUSIONS Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.
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Affiliation(s)
- Stefan Kraft
- From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Dr Kraft); and the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts (Dr Granter)
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Alfaro AC, Roberts B, Kwong L, Bijlsma MF, Roelink H. Ptch2 mediates the Shh response in Ptch1-/- cells. Development 2014; 141:3331-9. [PMID: 25085974 DOI: 10.1242/dev.110056] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Hedgehog (Hh) signaling response is regulated by the interaction of three key components that include the sonic hedgehog (Shh) ligand, its receptor patched 1 (Ptch1) and the pathway activator smoothened (Smo). Under the prevailing model of Shh pathway activation, the binding of Shh to Ptch1 (the key Shh receptor) results in the release of Ptch1-mediated inhibition of Smo, leading to Smo activation and subsequent cell-autonomous activation of the Shh response. Consistent with this model, Ptch1(-/-) cells show a strong upregulation of the Shh response. Our finding that this response can be inhibited by the Shh-blocking antibody 5E1 indicates that the Shh response in Ptch1(-/-) cells remains ligand dependent. Furthermore, we find that Shh induces a strong response in Ptch1(-/-);Shh(-/-) cells, and that Ptch1(-/-) fibroblasts retain their ability to migrate towards Shh, demonstrating that Ptch1(-/-) cells remain sensitive to Shh. Expression of a dominant-negative Ptch1 mutant in the developing chick neural tube had no effect on Shh-mediated patterning, but expression of a dominant-negative form of patched 2 (Ptch2) caused an activation of the Shh response. This indicates that, at early developmental stages, Ptch2 functions to suppress Shh signaling. We found that Ptch1(-/-);Ptch2(-/-) cells cannot further activate the Shh response, demonstrating that Ptch2 mediates the response to Shh in the absence of Ptch1.
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Affiliation(s)
- Astrid C Alfaro
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Brock Roberts
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Lina Kwong
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Maarten F Bijlsma
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Henk Roelink
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
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Li W, Lin CY, Shang C, Han P, Xiong Y, Lin CJ, Yang J, Selleri L, Chang CP. Pbx1 activates Fgf10 in the mesenchyme of developing lungs. Genesis 2014; 52:399-407. [PMID: 24591256 DOI: 10.1002/dvg.22764] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 02/20/2014] [Accepted: 02/21/2014] [Indexed: 01/19/2023]
Abstract
Insufficiency of surfactants is a core factor in respiratory distress syndrome, which causes apnea and neonatal death, particularly in preterm infants. Surfactant proteins are secreted by alveolar type II cells in the lung epithelium, the differentiation of which is regulated by Fgf10 elaborated by the adjacent mesenchyme. However, the molecular regulation of mesenchymal Fgf10 during lung development has not been fully understood. Here, we show that Pbx1, a homeodomain transcription factor, is required in the lung mesenchyme for the expression of Fgf10. Mouse embryos lacking Pbx1 in the lung mesenchyme show compact terminal saccules and perinatal lethality with failure of postnatal alveolar expansion. Mutant embryos had severely reduced expression of Fgf10 and surfactant genes (Spa, Spb, Spc, and Spd) that are essential for alveolar expansion for gas exchange at birth. Molecularly, Pbx1 directly binds to the Fgf10 promoter and cooperates with Meis and Hox proteins to transcriptionally activate Fgf10. Our results thus show how Pbx1 controls Fgf10 in the developing lung.
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Affiliation(s)
- Wei Li
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California
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Rucki AA, Zheng L. Pancreatic cancer stroma: Understanding biology leads to new therapeutic strategies. World J Gastroenterol 2014; 20:2237-2246. [PMID: 24605023 PMCID: PMC3942829 DOI: 10.3748/wjg.v20.i9.2237] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/14/2013] [Accepted: 01/20/2014] [Indexed: 02/06/2023] Open
Abstract
Pancreatic ductal adenocarcinoma (PDA) is among the deadliest cancers in the United States and in the world. Late diagnosis, early metastasis and lack of effective therapy are among the reasons why only 6% of patients diagnosed with PDA survive past 5 years. Despite development of targeted therapy against other cancers, little progression has been made in the treatment of PDA. Therefore, there is an urgent need for the development of new treatments. However, in order to proceed with treatments, the complicated biology of PDA needs to be understood first. Interestingly, majority of the tumor volume is not made of malignant epithelial cells but of stroma. In recent years, it has become evident that there is an important interaction between the stromal compartment and the less prevalent malignant cells, leading to cancer progression. The stroma not only serves as a growth promoting source of signals but it is also a physical barrier to drug delivery. Understanding the tumor-stroma signaling leading to development of desmoplastic reaction and tumor progression can lead to the development of therapies to decrease stromal activity and improve drug delivery. In this review, we focus on how the current understanding of biology of the pancreatic tumor microenvironment can be translated into the development of targeted therapy.
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66
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Corvino V, Marchese E, Podda MV, Lattanzi W, Giannetti S, Di Maria V, Cocco S, Grassi C, Michetti F, Geloso MC. The neurogenic effects of exogenous neuropeptide Y: early molecular events and long-lasting effects in the hippocampus of trimethyltin-treated rats. PLoS One 2014; 9:e88294. [PMID: 24516629 PMCID: PMC3917853 DOI: 10.1371/journal.pone.0088294] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 01/05/2014] [Indexed: 01/08/2023] Open
Abstract
Modulation of endogenous neurogenesis is regarded as a promising challenge in neuroprotection. In the rat model of hippocampal neurodegeneration obtained by Trimethyltin (TMT) administration (8 mg/kg), characterised by selective pyramidal cell loss, enhanced neurogenesis, seizures and cognitive impairment, we previously demonstrated a proliferative role of exogenous neuropeptide Y (NPY), on dentate progenitors in the early phases of neurodegeneration. To investigate the functional integration of newly-born neurons, here we studied in adult rats the long-term effects of intracerebroventricular administration of NPY (2 µg/2 µl, 4 days after TMT-treatment), which plays an adjuvant role in neurodegeneration and epilepsy. Our results indicate that 30 days after NPY administration the number of new neurons was still higher in TMT+NPY-treated rats than in control+saline group. As a functional correlate of the integration of new neurons into the hippocampal network, long-term potentiation recorded in Dentate Gyrus (DG) in the absence of GABAA receptor blockade was higher in the TMT+NPY-treated group than in all other groups. Furthermore, qPCR analysis of Kruppel-like factor 9, a transcription factor essential for late-phase maturation of neurons in the DG, and of the cyclin-dependent kinase 5, critically involved in the maturation and dendrite extension of newly-born neurons, revealed a significant up-regulation of both genes in TMT+NPY-treated rats compared with all other groups. To explore the early molecular events activated by NPY administration, the Sonic Hedgehog (Shh) signalling pathway, which participates in the maintenance of the neurogenic hippocampal niche, was evaluated by qPCR 1, 3 and 5 days after NPY-treatment. An early significant up-regulation of Shh expression was detected in TMT+NPY-treated rats compared with all other groups, associated with a modulation of downstream genes. Our data indicate that the neurogenic effect of NPY administration during TMT-induced neurodegeneration involves early Shh pathway activation and results in a functional integration of newly-generated neurons into the local circuit.
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Affiliation(s)
- Valentina Corvino
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Elisa Marchese
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Maria Vittoria Podda
- Institute of Human Physiology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Wanda Lattanzi
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Stefano Giannetti
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Valentina Di Maria
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Sara Cocco
- Institute of Human Physiology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Claudio Grassi
- Institute of Human Physiology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Fabrizio Michetti
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Maria Concetta Geloso
- Institute of Anatomy and Cell Biology - Università Cattolica del Sacro Cuore, Rome, Italy
- * E-mail:
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67
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Yip HK. Retinal stem cells and regeneration of vision system. Anat Rec (Hoboken) 2013; 297:137-60. [PMID: 24293400 DOI: 10.1002/ar.22800] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 09/13/2013] [Indexed: 12/14/2022]
Abstract
The vertebrate retina is a well-characterized model for studying neurogenesis. Retinal neurons and glia are generated in a conserved order from a pool of mutlipotent progenitor cells. During retinal development, retinal stem/progenitor cells (RPC) change their competency over time under the influence of intrinsic (such as transcriptional factors) and extrinsic factors (such as growth factors). In this review, we summarize the roles of these factors, together with the understanding of the signaling pathways that regulate eye development. The information about the interactions between intrinsic and extrinsic factors for retinal cell fate specification is useful to regenerate specific retinal neurons from RPCs. Recent studies have identified RPCs in the retina, which may have important implications in health and disease. Despite the recent advances in stem cell biology, our understanding of many aspects of RPCs in the eye remains limited. PRCs are present in the developing eye of all vertebrates and remain active in lower vertebrates throughout life. In mammals, however, PRCs are quiescent and exhibit very little activity and thus have low capacity for retinal regeneration. A number of different cellular sources of RPCs have been identified in the vertebrate retina. These include PRCs at the retinal margin, pigmented cells in the ciliary body, iris, and retinal pigment epithelium, and Müller cells within the retina. Because PRCs can be isolated and expanded from immature and mature eyes, it is possible now to study these cells in culture and after transplantation in the degenerated retinal tissue. We also examine current knowledge of intrinsic RPCs, and human embryonic stems and induced pluripotent stem cells as potential sources for cell transplant therapy to regenerate the diseased retina.
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Affiliation(s)
- Henry K Yip
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Adminstrative Region, People's Republic of China; Research Center of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Adminstrative Region, People's Republic of China; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Adminstrative Region, People's Republic of China
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68
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Nachtergaele S, Whalen DM, Mydock LK, Zhao Z, Malinauskas T, Krishnan K, Ingham PW, Covey DF, Siebold C, Rohatgi R. Structure and function of the Smoothened extracellular domain in vertebrate Hedgehog signaling. eLife 2013; 2:e01340. [PMID: 24171105 PMCID: PMC3809587 DOI: 10.7554/elife.01340] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/26/2013] [Indexed: 12/14/2022] Open
Abstract
The Hedgehog (Hh) signal is transduced across the membrane by the heptahelical protein Smoothened (Smo), a developmental regulator, oncoprotein and drug target in oncology. We present the 2.3 Å crystal structure of the extracellular cysteine rich domain (CRD) of vertebrate Smo and show that it binds to oxysterols, endogenous lipids that activate Hh signaling. The oxysterol-binding groove in the Smo CRD is analogous to that used by Frizzled 8 to bind to the palmitoleyl group of Wnt ligands and to similar pockets used by other Frizzled-like CRDs to bind hydrophobic ligands. The CRD is required for signaling in response to native Hh ligands, showing that it is an important regulatory module for Smo activation. Indeed, targeting of the Smo CRD by oxysterol-inspired small molecules can block signaling by all known classes of Hh activators and by clinically relevant Smo mutants. DOI:http://dx.doi.org/10.7554/eLife.01340.001.
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MESH Headings
- Animals
- Binding Sites
- Crystallography, X-Ray
- Embryo, Nonmammalian
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Developmental
- Hedgehog Proteins/chemistry
- Hedgehog Proteins/genetics
- Hedgehog Proteins/metabolism
- Ligands
- Mice
- Models, Molecular
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- Smoothened Receptor
- Sterols/chemistry
- Structure-Activity Relationship
- Zebrafish/genetics
- Zebrafish/growth & development
- Zebrafish/metabolism
- Zebrafish Proteins/antagonists & inhibitors
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Sigrid Nachtergaele
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Daniel M Whalen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Laurel K Mydock
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Zhonghua Zhao
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Philip W Ingham
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
- Lee Kong Chian School of Medicine, Imperial College London/Nanyang Technological University, Singapore, Singapore
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rajat Rohatgi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
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PTCH1 gene mutations in Keratocystic odontogenic tumors: a study of 43 Chinese patients and a systematic review. PLoS One 2013; 8:e77305. [PMID: 24204797 PMCID: PMC3804548 DOI: 10.1371/journal.pone.0077305] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 09/04/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The keratocystic odontogenic tumor (KCOT) is a locally aggressive cystic jaw lesion that occurs sporadically or in association with nevoid basal cell carcinoma syndrome (NBCCS). PTCH1, the gene responsible for NBCCS, may play an important role in sporadic KCOTs. In this study, we analyzed and compared the distribution pattern of PTCH1 mutations in patients with sporadic and NBCCS-associated KCOTs. METHODS We detected PTCH1 mutations in 14 patients with NBCCS-associated KCOTs and 29 patients with sporadic KCOTs by direct sequencing. In addition, five electronic databases were searched for studies detecting PTCH1 mutations in individuals with NBCCS-associated or sporadic KCOTs, published between January 1996 and June 2013 in English language. RESULTS We identified 15 mutations in 11 cases with NBCCS-associated KCOTs and 19 mutations in 13 cases with sporadic KCOTs. In addition, a total of 204 PTCH1 mutations (187 mutations from 210 cases with NBCCS-associated and 17 mutations from 57 cases with sporadic KCOTs) were compiled from 78 published papers. CONCLUSIONS Our study indicates that mutations in transmembrane 2 (TM2) are closely related to the development of sporadic KCOTs. Moreover, for the early diagnosis of NBCCS, a genetic analysis of the PTCH1 gene should be included in the new diagnostic criteria.
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Abstract
The tumor suppressor Patched1 (Ptch1) possesses well-described roles in regulating sonic hedgehog (SHH) signaling in the skin and preventing the formation of basal cell carcinomas (BCCs). In this issue, Kang et al. extend their previous work to show that a naturally occurring allele of Ptch1 found in FVB mice promotes early squamous cell carcinoma (SCC) growth without aberrant activation of the SHH pathway. The study reveals new roles for Ptch1 that lie at the nexus between BCC and SCC formation.
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71
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Peukert S, He F, Dai M, Zhang R, Sun Y, Miller-Moslin K, McEwan M, Lagu B, Wang K, Yusuff N, Bourret A, Ramamurthy A, Maniara W, Amaral A, Vattay A, Wang A, Guo R, Yuan J, Green J, Williams J, Buonamici S, Kelleher JF, Dorsch M. Discovery of NVP-LEQ506, a Second-Generation Inhibitor of Smoothened. ChemMedChem 2013; 8:1261-5. [DOI: 10.1002/cmdc.201300217] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Indexed: 01/17/2023]
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72
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Sonic hedgehog enhances the proliferation and osteogenic differentiation of bone marrow-derived mesenchymal stem cells. Cell Biol Int 2012; 36:349-55. [PMID: 22149964 DOI: 10.1042/cbi20110284] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
MSCs (mesenchymal stem cells) may be promising seed cells for tissue regeneration because of their self-renewal and multi-differentiation potential. Shh (sonic hedgehog) is involved in the skeletal formation during embryo development and skeletal regeneration. However, how Shh regulates the biological characteristics of BM-MSCs (bone marrow-derived MSCs) is poorly understood. We have investigated the effect of rShh-N (recombinant N-terminal Shh) on the proliferation and osteogenic differentiation of rBM-MSCs (rat BM-MSCs) in vitro. rBM-MSCs were treated with rShh-N at concentrations up to 200 ng/ml. Proliferation and colony-forming ability of rBM-MSCs were increased in a dose-dependent manner. rShh-N increased the ratio of cells in S and G2/M phase, as well as the number of Ki-67+ cells. In addition, ALP (alkaline phosphatase) activity and matrix mineralization were enhanced by 200 ng/ml rShh-N. Real-time PCR showed that rShh-N (200 ng/ml) up-regulated the expression of genes encoding Cbfa-1 (core-binding factor α1), osteocalcin, ALP and collagen type I in rBM-MSCs. This information reveals some potential of rShh-N in the therapeutics of bone-related diseases.
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73
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Trzaskowski B, Latek D, Yuan S, Ghoshdastider U, Debinski A, Filipek S. Action of molecular switches in GPCRs--theoretical and experimental studies. Curr Med Chem 2012; 19:1090-109. [PMID: 22300046 PMCID: PMC3343417 DOI: 10.2174/092986712799320556] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 12/30/2011] [Accepted: 01/02/2012] [Indexed: 01/14/2023]
Abstract
G protein coupled receptors (GPCRs), also called 7TM receptors, form a huge superfamily of membrane proteins that, upon activation by extracellular agonists, pass the signal to the cell interior. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. Biochemical and crystallographic methods together with molecular dynamics simulations and other theoretical techniques provided models of the receptor activation based on the action of so-called "molecular switches" buried in the receptor structure. They are changed by agonists but also by inverse agonists evoking an ensemble of activation states leading toward different activation pathways. Switches discovered so far include the ionic lock switch, the 3-7 lock switch, the tyrosine toggle switch linked with the nPxxy motif in TM7, and the transmission switch. The latter one was proposed instead of the tryptophan rotamer toggle switch because no change of the rotamer was observed in structures of activated receptors. The global toggle switch suggested earlier consisting of a vertical rigid motion of TM6, seems also to be implausible based on the recent crystal structures of GPCRs with agonists. Theoretical and experimental methods (crystallography, NMR, specific spectroscopic methods like FRET/BRET but also single-molecule-force-spectroscopy) are currently used to study the effect of ligands on the receptor structure, location of stable structural segments/domains of GPCRs, and to answer the still open question on how ligands are binding: either via ensemble of conformational receptor states or rather via induced fit mechanisms. On the other hand the structural investigations of homoand heterodimers and higher oligomers revealed the mechanism of allosteric signal transmission and receptor activation that could lead to design highly effective and selective allosteric or ago-allosteric drugs.
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Affiliation(s)
- B Trzaskowski
- Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
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74
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Dashti M, Peppelenbosch MP, Rezaee F. Hedgehog signalling as an antagonist of ageing and its associated diseases. Bioessays 2012; 34:849-56. [PMID: 22903465 DOI: 10.1002/bies.201200049] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hedgehog is an important morphogenic signal that directs pattern formation during embryogenesis, but its activity also remains present through adult life. It is now becoming increasingly clear that during the reproductive phase of life and beyond it continues to direct cell renewal (which is essential to combat the chronic environmental stress to which the body is constantly exposed) and counteracts vascular, osteolytic and sometimes oncological insults to the body. Conversely, down-regulation of hedgehog signalling is associated with ageing-related diseases such as type 2 diabetes, neurodegeneration, atherosclerosis and osteoporosis. Hence, in this essay we argue that hedgehog signalling is not only important at the start of life, but also constitutes an important anti-geriatric influence, and that enhanced understanding of its properties may contribute to developing rational strategies for healthy ageing and prevention of ageing-related diseases.
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Affiliation(s)
- Monireh Dashti
- Department of Cell Biology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
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75
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Abstract
The original hedgehog (hh) gene was found in Drosophila and named for the appearance of a mutant phenotype which causes an embryo to be covered with pointy denticles, thus resembling a hedgehog. The hedgehog family consists of sonic hedgehog (Shh), desert hedgehog (Dhh), and Indian hedgehog (Ihh). Shh is found in vertebrates and the best studied ligand of the hedgehog signaling pathway (Gilbert, 2000). It plays an important role in regulating vertebrate organogenesis, such as in the growth of digits on limbs and organization of the brain, and earlier studies also show that it is important during retinal development (for a review, see Amato et al., 2004). Hedgehog expression drives waves of neurogenesis in animal retina, although genetic programs that control its expression are poorly elucidated. Recently, a novel transcriptional cascade which involves the atonal and Iroquois gene family was proposed in the regulation of hedgehog waves during vertebrate retinal development (Choy et al., 2010). This chapter will focus on Shh by addressing its signaling mechanisms and roles in vertebrate eye development, as well as a novel finding in retinogenesis.
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76
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Anderson E, Peluso S, Lettice LA, Hill RE. Human limb abnormalities caused by disruption of hedgehog signaling. Trends Genet 2012; 28:364-73. [DOI: 10.1016/j.tig.2012.03.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 03/26/2012] [Accepted: 03/26/2012] [Indexed: 12/23/2022]
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77
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Wilson SL, Wilson JP, Wang C, Wang B, McConnell SK. Primary cilia and Gli3 activity regulate cerebral cortical size. Dev Neurobiol 2012; 72:1196-212. [PMID: 21976438 DOI: 10.1002/dneu.20985] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 09/15/2011] [Accepted: 09/28/2011] [Indexed: 01/15/2023]
Abstract
During neural development patterning, neurogenesis, and overall growth are highly regulated and coordinated between different brain regions. Here, we show that primary cilia and the regulation of Gli activity are necessary for the normal expansion of the cerebral cortex. We show that loss of Kif3a, an important functional component of primary cilia, leads to the degeneration of primary cilia, marked overgrowth of the cortex, and altered cell cycle kinetics within cortical progenitors. The G1 phase of the cell cycle is shortened through a mechanism likely involving reduced Gli3 activity and a resulting increase in expression of cyclin D1 and Fgf15. The defects in Gli3 activity alone are sufficient to accelerate cell cycle kinetics and cause the molecular changes seen in brains that lack cilia. Finally, we show that levels of full-length and repressor Gli3 proteins are tightly regulated during normal development and correlate with changes in expression of two known Shh-target genes, CyclinD1 and Fgf15, and with the normal lengthening of the cell cycle during corticogenesis. These data suggest that Gli3 activity is regulated through the primary cilium to control cell cycle length in the cortex and thus determine cortical size.
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Affiliation(s)
- Sandra L Wilson
- Department of Biology, Stanford University, Stanford, California 94305, USA
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78
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Basson MA. Signaling in cell differentiation and morphogenesis. Cold Spring Harb Perspect Biol 2012; 4:cshperspect.a008151. [PMID: 22570373 DOI: 10.1101/cshperspect.a008151] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
All the information to make a complete, fully functional living organism is encoded within the genome of the fertilized oocyte. How is this genetic code translated into the vast array of cellular behaviors that unfold during the course of embryonic development, as the zygote slowly morphs into a new organism? Studies over the last 30 years or so have shown that many of these cellular processes are driven by secreted or membrane-bound signaling molecules. Elucidating how the genetic code is translated into instructions or signals during embryogenesis, how signals are generated at the correct time and place and at the appropriate level, and finally, how these instructions are interpreted and put into action, are some of the central questions of developmental biology. Our understanding of the causes of congenital malformations and disease has improved substantially with the rapid advances in our knowledge of signaling pathways and their regulation during development. In this article, I review some of the signaling pathways that play essential roles during embryonic development. These examples show some of the mechanisms used by cells to receive and interpret developmental signals. I also discuss how signaling pathways downstream from these signals are regulated and how they induce specific cellular responses that ultimately affect cell fate and morphogenesis.
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Affiliation(s)
- M Albert Basson
- Department of Craniofacial Development, King's College London, United Kingdom.
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79
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Ryan KE, Chiang C. Hedgehog secretion and signal transduction in vertebrates. J Biol Chem 2012; 287:17905-13. [PMID: 22474285 DOI: 10.1074/jbc.r112.356006] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signaling by the Hedgehog (Hh) family of secreted proteins is essential for proper embryonic patterning and development. Dysregulation of Hh signaling is associated with a variety of human diseases ranging from developmental disorders such as holoprosencephaly to certain forms of cancer, including medulloblastoma and basal cell carcinoma. Genetic studies in flies and mice have shaped our understanding of Hh signaling and revealed that nearly all core components of the pathway are highly conserved. Although many aspects of the Drosophila Hh pathway are conserved in vertebrates, mechanistic differences between the two species have begun to emerge. Perhaps the most striking divergence in vertebrate Hh signaling is its dependence on the primary cilium, a vestigial organelle that is largely absent in flies. This minireview will provide an overview of Hh signaling and present recent insights into vertebrate Hh secretion, receptor binding, and signal transduction.
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Affiliation(s)
- Kaitlyn E Ryan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
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80
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Shi S, Deng YZ, Zhao JS, Ji XD, Shi J, Feng YX, Li G, Li JJ, Zhu D, Koeffler HP, Zhao Y, Xie D. RACK1 promotes non-small-cell lung cancer tumorigenicity through activating sonic hedgehog signaling pathway. J Biol Chem 2012; 287:7845-58. [PMID: 22262830 DOI: 10.1074/jbc.m111.315416] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-small-cell lung cancer (NSCLC) is a deadly disease due to lack of effective diagnosis biomarker and therapeutic target. Much effort has been made in defining gene defects in NSCLC, but its full molecular pathogenesis remains unexplored. Here, we found RACK1 (receptor of activated kinase 1) was elevated in most NSCLC, and its expression level correlated with key pathological characteristics including tumor differentiation, stage, and metastasis. In addition, RACK1 activated sonic hedgehog signaling pathway by interacting with and activating Smoothened to mediate Gli1-dependent transcription in NSCLC cells. And silencing RACK1 dramatically inhibited in vivo tumor growth and metastasis by blocking the sonic hedgehog signaling pathway. These results suggest that RACK1 represents a new promising diagnosis biomarker and therapeutic target for NSCLC.
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Affiliation(s)
- Shuo Shi
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Graduate School of Chinese Academy of Sciences, Shanghai 200031, China
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Oxysterols are allosteric activators of the oncoprotein Smoothened. Nat Chem Biol 2012; 8:211-20. [PMID: 22231273 PMCID: PMC3262054 DOI: 10.1038/nchembio.765] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 11/03/2011] [Indexed: 12/13/2022]
Abstract
Oxysterols are a class of endogenous signaling molecules that can activate the Hedgehog pathway, which has critical roles in development, regeneration and cancer. However, it has been unclear how oxysterols influence Hedgehog signaling, including whether their effects are mediated through a protein target or indirectly through effects on membrane properties. To answer this question, we synthesized the enantiomer and an epimer of the most potent oxysterol, 20(S)-hydroxycholesterol. Using these molecules, we show that the effects of oxysterols on Hedgehog signaling are exquisitely stereoselective, consistent with the hypothesis that they function through a specific protein target. We present several lines of evidence that this protein target is the seven-pass transmembrane protein Smoothened, a major drug target in oncology. Our work suggests that these enigmatic sterols, which have multiple effects on cell physiology, may act as ligands for signaling receptors and provides a generally applicable framework for probing sterol signaling mechanisms.
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82
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Abstract
Protein kinase A (PKA) is a well-known kinase that plays fundamental roles in a variety of biological processes. In Hedgehog-responsive cells, PKA plays key roles in proliferation and fate specification by modulating the transduction of Hedgehog signaling. In the absence of Hedgehog, a basal level of PKA activity represses the transcription of Hedgehog target genes. The main substrates of PKA in this process are the Ci/Gli family of bipotential transcription factors, which activate and repress Hedgehog target gene expression. PKA phosphorylates Ci/Gli, promoting the production of the repressor forms of Ci/Gli and thus repressing Hedgehog target gene expression. In contrast, the activation of Hedgehog signaling in response to Hedgehog increases the active forms of Ci/Gli, resulting in Hedgehog target gene expression. Because both decreased and increased levels of PKA activity cause abnormal cell proliferation and alter cell fate specification, the basal level of PKA activity in Hedgehog-responsive cells should be precisely regulated. However, the mechanism by which PKA activity is regulated remains obscure and appears to vary between cell types, tissues, and organisms. To date, two mechanisms have been proposed. One is a classical mechanism in which PKA activity is regulated by a small second messenger, cAMP; the other is a novel mechanism in which PKA activity is regulated by a protein, Misty somites.
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83
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The hedgehog pathway conditions the bone microenvironment for osteolytic metastasis of breast cancer. Int J Breast Cancer 2011; 2012:298623. [PMID: 22295244 PMCID: PMC3262601 DOI: 10.1155/2012/298623] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 09/06/2011] [Accepted: 09/08/2011] [Indexed: 01/29/2023] Open
Abstract
The microenvironment at the site of tumor metastasis plays a key role in determining the fate of the metastasizing tumor cells. This ultimately has a direct impact on the progression of cancer. Bone is the preferred site of metastasis of breast cancer. Painful, debilitating osteolytic lesions are formed as a result of crosstalk between breast cancer cells and cells in the bone, predominantly the osteoblasts and osteoclasts. In this paper, we have discussed the temporal and spatial role of hedgehog (Hh) signaling in influencing the fate of metastatic breast cancer cells in bone. By virtue of its secreted ligands, the Hh pathway is capable of homotypic and heterotypic signaling and consequently altering the microenvironment in the bone. We also have put into perspective the therapeutic implications of using Hh inhibitors to prevent and/or treat bone metastases of breast cancer.
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84
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Bibliowicz J, Gross JM. Ectopic proliferation contributes to retinal dysplasia in the juvenile zebrafish patched2 mutant eye. Invest Ophthalmol Vis Sci 2011; 52:8868-77. [PMID: 22003118 DOI: 10.1167/iovs.11-8033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Patched is a well-studied tumor suppressor and negative regulator of the Hedgehog (Hh) pathway. Earlier work in this laboratory has shown that embryonic zebrafish patched2 (ptc2) mutant retinas possess an expanded ciliary marginal zone (CMZ) and phenotypes similar to those in human patients with basal cell naevus syndrome (BCNS), a congenital disorder linked to mutations in the human PTCH gene. This study extends the analysis of retinal structure and homeostasis in ptc2-/- mutants to juvenile stages, to determine whether Patched 2 function is essential in the postembryonic eye. METHODS Histologic, immunohistochemical, and molecular analyses were used to characterize retinal defects in the 6-week-old juvenile ptc2-/- retina. RESULTS Juvenile ptc2-/- mutants exhibited peripheral retinal dysplasias that included the presence of ectopic neuronal clusters in the inner nuclear layer (INL) and regions of disrupted retinal lamination. Retinal dysplasias were locally associated with ectopic proliferation. BrdU/EdU labeling and immunohistochemistry assays demonstrated that a population of ectopically proliferating cells gave rise to the ectopic neuronal clusters in the INL of ptc2-/- mutants and that this contributed to retinal dysplasia in the mutant eye. CONCLUSIONS These results demonstrate a direct link between overproliferation and retinal dysplasia in the ptc2-/- juvenile retina and establish ectopic proliferation as the likely cellular underpinning of retinal dysplasia in juvenile ptc2-/- mutants.
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Affiliation(s)
- Jonathan Bibliowicz
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, Texas, USA
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85
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Shh signaling guides spatial pathfinding of raphespinal tract axons by multidirectional repulsion. Cell Res 2011; 22:697-716. [PMID: 22064698 DOI: 10.1038/cr.2011.172] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Relatively little is known about the molecular mechanisms underlying spatial pathfinding in the descending serotonergic raphespinal tract (RST) in the developing spinal cord, one of the most important nerve pathways for pain, sensory and motor functions. We provide evidence that ventral floor plate-secreted Sonic hedgehog (Shh) is responsible for the establishment of decreasing gradients in both the anterior-to-posterior (A-P) and the medial-to-lateral (M-L) directions in the ventral spinal cord during serotonergic RST axon projection. Downstream components of the Shh pathway, Patched 1 (Ptch1) and Smoothened (Smo), were expressed in the serotonergic caudal raphe nuclei and enriched in the descending serotonergic RST axons. Diffusible Shh repulsion of serotonergic RST axons was shown to be mediated by Shh-Ptch1 interactions and derepression of Smo. Using a co-culture assay, we showed that A-P graded repulsion mediated by Shh signaling pushed the serotonergic axons caudally through the ventral spinal cord and M-L graded repulsion mediated by Shh signaling simultaneously restricted the serotonergic axons to the ventral and ventral-lateral funiculus. Prominent pathfinding errors of serotonergic RST axons were observed in various Shh, Ptch1 and Smo mutants. We conclude that Shh signaling-mediated multidirectional repulsion is required to push descending serotonergic RST axons in the A-P direction, and to restrict these axons to the ventral and ventral-lateral funiculus in the M-L direction. This is the first demonstration that Shh signaling-mediated multidirectional repulsion of serotonergic RST axons maintains spatial axon pathfinding in the developing spinal cord.
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86
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Balbuena J, Pachon G, Lopez-Torrents G, Aran JM, Castresana JS, Petriz J. ABCG2 is required to control the sonic hedgehog pathway in side population cells with stem-like properties. Cytometry A 2011; 79:672-83. [PMID: 21774076 DOI: 10.1002/cyto.a.21103] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 05/23/2011] [Accepted: 06/15/2011] [Indexed: 11/06/2022]
Abstract
The Sonic Hedgehog (Hh) pathway has been implicated in the maintenance of stem or progenitor cells in many adult tissues. Importantly, abnormal Hh pathway activation is also associated with initiation of neoplasia, but its role in tumor growth is still unclear. Here, we demonstrate that cyclopamine, a plant-derived alkaloid product used to inhibit the Hh signaling pathway, reduces the Side Population (SP) obtained by Hoechst 33342 (Ho342) dye measurements. In addition, cyclopamine is able to modulate, along with oxysterols and other products, the ABCG2 transporter by increasing Ho342 and mitoxantrone uptake. Therefore, if the SP is solely measured as a Ho342 dye extruding fraction, this may be significantly modulated by the inhibition of ABCG2 transport fraction, independently from the action of cyclopamine on the Hh pathway. Our results indicate that ABCG2 may act in the upstream regulation of the Hh signaling pathway to protect the stemness of the SP compartment, giving support to the cancer stem cell hypothesis and suggesting that ABCG2 is not only critical for increased resistance to anticancer agents.
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Affiliation(s)
- Jana Balbuena
- Brain Tumor Biology Unit, CIFA, University of Navarra School of Sciences, Pamplona, Spain
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87
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Ishii H, Saito T. Cancer metastasis as disrupted developmental phenotype. Curr Genomics 2011; 9:25-8. [PMID: 19424481 PMCID: PMC2674302 DOI: 10.2174/138920208783884919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 02/29/2008] [Accepted: 02/29/2008] [Indexed: 12/30/2022] Open
Abstract
Cancer metastasis is a complex processes, associated with the invasion to tissues with extensive degradation of the surrounding normal components, penetration into vessels, circulation, and then invasion to normal tissues in body. It would be not surprising that tumor cells usurp pathways critical to the developing embryo during metastasis. For the better understanding of tumor metastasis, this review will highlight the recent progress and significance of the signal transduction pathways, relevant to developmental biology.
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Affiliation(s)
- Hideshi Ishii
- Center for Molecular Medicine, Jichi Medical University, Tochigi
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88
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Takebe N, Warren RQ, Ivy SP. Breast cancer growth and metastasis: interplay between cancer stem cells, embryonic signaling pathways and epithelial-to-mesenchymal transition. Breast Cancer Res 2011; 13:211. [PMID: 21672282 PMCID: PMC3218933 DOI: 10.1186/bcr2876] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Induction of epithelial-to-mesenchymal transition (EMT) in cancer stem cells (CSCs) can occur as the result of embryonic pathway signaling. Activation of Hedgehog (Hh), Wnt, Notch, or transforming growth factor-β leads to the upregulation of a group of transcriptional factors that drive EMT. This process leads to the transformation of adhesive, non-mobile, epithelial-like tumor cells into cells with a mobile, invasive phenotype. CSCs and the EMT process are currently being investigated for the role they play in driving metastatic tumor formation in breast cancer. Both are very closely associated with embryonic signaling pathways that stimulate self-renewal properties of CSCs and EMT-inducing transcription factors. Understanding these mechanisms and embryonic signaling pathways may lead to new opportunities for developing therapeutic agents to help prevent metastasis in breast cancer. In this review, we examine embryonic signaling pathways, CSCs, and factors affecting EMT.
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Affiliation(s)
- Naoko Takebe
- National Cancer Institute, Division of Cancer Treatment and Diagnosis, Cancer Therapy Evaluation Program, Investigational Drug Branch, Rockville, Maryland 20852, USA.
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89
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Suppressor of fused is required to maintain the multipotency of neural progenitor cells in the retina. J Neurosci 2011; 31:5169-80. [PMID: 21451052 DOI: 10.1523/jneurosci.5495-10.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The morphogen sonic hedgehog (Shh) plays a crucial role in development of the CNS, including the neural retina. Suppressor of fused (Sufu) has been recently identified as a critical regulator of Hh signaling in mammals. However, the precise roles that Sufu plays in the regulation of proliferation and cell-fate decisions in neural progenitors is unknown. Here, we have addressed these questions by conditionally deleting Sufu in mouse multipotent retinal progenitor cells (RPCs). Sufu deletion in RPCs results in transient increases in Hh activity and proliferation followed by developmentally premature cell-cycle exit. Importantly, we demonstrate a novel role for Sufu in the maintenance of multipotency in RPCs. Sufu-null RPCs downregulate transcription factors required to specify or maintain RPC identity (Rax, Vsx2) and multipotency (Pax6) but continue to express the neural progenitor marker Sox2. These cells fail to express retinal lineage-specific transcription factors, such as Math5, and adopt an amacrine or horizontal cell fate at the expense of all other classes of retinal neurons. Genetic elimination of Gli2 in Sufu-null RPCs attenuates Hh pathway activity and restores multipotency in neural progenitors. These data provide novel evidence that Sufu-mediated antagonism of Hh/Gli2 signaling is required to maintain RPC multipotency and identity.
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90
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Ingham PW, Nakano Y, Seger C. Mechanisms and functions of Hedgehog signalling across the metazoa. Nat Rev Genet 2011; 12:393-406. [PMID: 21502959 DOI: 10.1038/nrg2984] [Citation(s) in RCA: 438] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hedgehog proteins constitute one of a small number of families of secreted signals that have a central role in the development of metazoans. Genetic analyses in flies, fish and mice have uncovered the major components of the pathway that transduces Hedgehog signals, and recent genome sequence projects have provided clues about its evolutionary origins. In this Review we provide an updated overview of the mechanisms and functions of this signalling pathway, highlighting the conserved and divergent features of the pathway, as well as some of the common themes in its deployment that have emerged from recent studies.
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Affiliation(s)
- Philip W Ingham
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore.
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91
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A novel signaling pathway mediated by the nuclear targeting of C-terminal fragments of mammalian Patched 1. PLoS One 2011; 6:e18638. [PMID: 21533246 PMCID: PMC3076429 DOI: 10.1371/journal.pone.0018638] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 03/14/2011] [Indexed: 12/20/2022] Open
Abstract
Background Patched 1 (Ptc1) is a polytopic receptor protein that is essential for growth and differentiation. Its extracellular domains accept its ligand, Sonic Hedgehog, while the function of its C-terminal intracellular domain is largely obscure. Principal Findings In this study, we stably expressed human Ptc1 protein in HeLa cells and found that it is subjected to proteolytic cleavage at the C-terminus, resulting in the generation of soluble C-terminal fragments. These fragments accumulated in the nucleus, while the N-terminal region of Ptc1 remained in the cytoplasmic membrane fractions. Using an anti-Ptc1 C-terminal domain antibody, we provide conclusive evidence that C-terminal fragments of endogenous Ptc1 accumulate in the nucleus of C3H10T1/2 cells. Similar nuclear accumulation of endogenous C-terminal fragments was observed not only in C3H10T1/2 cells but also in mouse embryonic primary cells. Importantly, the C-terminal fragments of Ptc1 modulate transcriptional activity of Gli1. Conclusions Although Ptc1 protein was originally thought to be restricted to cell membrane fractions, our findings suggest that its C-terminal fragments can function as an alternative signal transducer that is directly transported to the cell nucleus.
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92
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Brechbiel JL, Ng JMY, Curran T. PTHrP treatment fails to rescue bone defects caused by Hedgehog pathway inhibition in young mice. Toxicol Pathol 2011; 39:478-85. [PMID: 21411723 DOI: 10.1177/0192623311399788] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The advent of molecular targeted therapies offers the hope of therapeutic advance in the fight against cancer. However, this hope is tempered by recent findings that certain targeted therapies may have unique side effects. The Hedgehog (HH) pathway is a potential target for treatment of several cancers, including basal cell carcinoma and a subset of medulloblastoma. Recent clinical trials in adults have shown responses to HH pathway inhibition in both basal cell carcinoma and medulloblastoma. However, concerns have been raised about the use of HH pathway inhibitors in children because of the role the HH pathway plays in development. Indeed, young mice treated with the HH pathway inhibitor HhAntag developed severe bone defects, including premature differentiation of chondrocytes, thinning of cortical bone, and fusion of the growth plate. In an effort to lessen the severity of bone defects caused by HhAntag, we treated young mice simultaneously with HhAntag and parathyroid hormone-related protein (PTHrP), which functions downstream of Indian Hedgehog to maintain chondrocytes in a proliferative state. The results show that whereas treatment with PTHrP causes a significant increase in trabecular bone, it does not prevent fusion of the growth plate induced by HhAntag.
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Affiliation(s)
- Jillian L Brechbiel
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Pennsylvania, PA 19104, USA
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93
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Soltanian S, Matin MM. Cancer stem cells and cancer therapy. Tumour Biol 2011; 32:425-40. [PMID: 21318290 DOI: 10.1007/s13277-011-0155-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 01/10/2011] [Indexed: 12/31/2022] Open
Abstract
Cancer stem cells (CSCs) are a subpopulation of tumour cells that possess the stem cell properties of self-renewal and differentiation. Stem cells might be the target cells responsible for malignant transformation, and tumour formation may be a disorder of stem cell self-renewal pathway. Epigenetic alterations and mutations of genes involved in signal transmissions may promote the formation of CSCs. These cells have been identified in many solid tumours including breast, brain, lung, prostate, testis, ovary, colon, skin, liver, and also in acute myeloid leukaemia. The CSC theory clarifies not only the issue of tumour initiation, development, metastasis and relapse, but also the ineffectiveness of conventional cancer therapies. Treatments directed against the bulk of the cancer cells may produce striking responses but they are unlikely to result in long-term remissions if the rare CSCs are not targeted. In this review, we consider the properties of CSCs and possible strategies for controlling the viability and tumourigenecity of these cells, including therapeutic models for selective elimination of CSCs and induction of their proper differentiation.
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Affiliation(s)
- Sara Soltanian
- Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
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94
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Abstract
In vertebrate hedgehog signaling, hedgehog ligands are processed to become bilipidated and then multimerize, which allows them to leave the signaling cell via Dispatched 1 and become transported via glypicans and megalin to the responding cells. Hedgehog then interacts with a complex of Patched 1 and Cdo/Boc, which activates endocytic Smoothened to the cilium. Patched 1 regulates the activity of Smoothened (1) via Vitamin D3, which inhibits Smoothened in the absence of hedgehog ligand or (2) via oxysterols, which activate Smoothened in the presence of hedgehog ligand. Hedgehog ligands also interact with Hip1, Patched 2, and Gas1, which regulate the range as well as the level of hedgehog signaling. In vertebrates, Smoothened is shortened at its C-terminal end and lacks most of the phosphorylation sites of importance in Drosophila. Cos2, also of importance in Drosophila, plays no role in mammalian transduction, nor do its homologs Kif7 and Kif27. The cilium may provide a function analogous to that of Cos2 by linking Smoothened to the modulation of Gli transcription factors. Disorders associated with the hedgehog signaling network follow, including nevoid basal cell carcinoma syndrome, holoprosencephaly, Smith-Lemli-Opitz syndrome, Greig cephalopolysyndactyly syndrome, Pallister-Hall syndrome, Carpenter syndrome, and Rubinstein-Taybi syndrome.
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Affiliation(s)
- M Michael Cohen
- Department of Oral & Maxillofacial Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
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95
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Bijlsma MF, Roelink H. Non-cell-autonomous signaling by Shh in tumors: challenges and opportunities for therapeutic targets. Expert Opin Ther Targets 2010; 14:693-702. [PMID: 20515293 DOI: 10.1517/14728222.2010.497488] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD The Hedgehog (Hh) pathway is required during many developmental events; in adults the Hedgehog pathway is involved in the maintenance of several stem cell niches. It is therefore not surprising that aberrantly regulated Hh pathway activity can cause birth defects in the developing organism, as well as neoplastic disease later in life. AREAS COVERED IN THIS REVIEW As a consequence of the involvement in pathogenesis, the Hh pathway components are subject to an intense scrutiny as potential targets for therapeutic agents. We aim to provide an overview of the biology of the Hh proteins and the cellular response, in conjunction with potential therapeutic interventions. WHAT THE READER WILL GAIN Specifically, we focus on the recently discovered non-cell-autonomous Shh signaling used by tumors and the implications of this for the design of treatment strategies. This should provide the reader with up-to-date knowledge on the role of the Hh pathway in tumor progression and the options to treat these malignancies. TAKE HOME MESSAGE An important concept that we advocate in this review is the need to recognize the need to target both the stromal and the tumor compartment in malignancies that rely on paracrine Shh signaling.
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Affiliation(s)
- Maarten F Bijlsma
- University of California Berkeley, Department of Molecular and Cell Biology, Berkeley, CA 94720-3204, USA
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96
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Bijlsma MF, Groot AP, Oduro JP, Franken RJ, Schoenmakers SHHF, Peppelenbosch MP, Spek CA. Hypoxia induces a hedgehog response mediated by HIF-1alpha. J Cell Mol Med 2010; 13:2053-2060. [PMID: 18774959 DOI: 10.1111/j.1582-4934.2008.00491.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Recently, it has become clear that the developmental hedgehog pathway is activated in ischaemic adult tissue where it aids in salvaging damaged tissue. The exact driving force for the initial hedgehog response is unclear and as most physiological and cellular processes are disturbed in ischaemic tissue, hedgehog-activating signals are hard to dissect. Here, we demonstrate that hypoxia per se is able to induce a rapid systemic hedgehog response in adult mice, as evident from expression of the pathway ligand, Sonic hedgehog, as well as the pathway activity marker Patched1 in various organs. Using in vitro models of hypoxia, we showed that the hedgehog response was transient and preceded by the accumulation of HIF-1alpha, which we hypothesized to communicate between hypoxia and hedgehog expression. Indeed, pharmacological inhibition, knockdown or genetic ablation of HIF-1alpha abolished hedgehog pathway activation. In conclusion, we have established that hypoxia is translated into a hedgehog response through HIF-1alpha and this mechanism is likely to be responsible for the hedgehog response observed in various ischaemia models.
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Affiliation(s)
- Maarten F Bijlsma
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands.,Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Angelique P Groot
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Jeremiah P Oduro
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Rutger J Franken
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Maikel P Peppelenbosch
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - C Arnold Spek
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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97
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Barzi M, Berenguer J, Menendez A, Alvarez-Rodriguez R, Pons S. Sonic-hedgehog-mediated proliferation requires the localization of PKA to the cilium base. J Cell Sci 2010; 123:62-9. [PMID: 20016067 DOI: 10.1242/jcs.060020] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cerebellar granular neuronal precursors (CGNPs) proliferate in response to the mitogenic activity of Sonic hedgehog (Shh), and this proliferation is negatively regulated by activation of cAMP-dependent protein kinase (PKA). In the basal state, the PKA catalytic subunits (C-PKA) are inactive because of their association with the regulatory subunits (R-PKA). As the level of cAMP increases, it binds to R-PKA, displacing and thereby activating the C-PKA. Here we report that, in the presence of Shh, inactive C-PKA accumulates at the cilium base of proliferative CGNPs whereas removal of Shh triggers the activation of PKA at this particular location. Furthermore, we demonstrate that the anchoring of the PKA holoenzyme to the cilium base is mediated by the specific binding of the type II PKA regulatory subunit (RII-PKA) to the A-kinase anchoring proteins (AKAPs). Disruption of the interaction between RII-PKA and AKAPs inhibits Shh activity and, therefore, blocks proliferation of CGNP cultures. Collectively, these results demonstrate that the pool of PKA localized to the cilium base of CGNP plays an essential role in the integration of Shh signal transduction.
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Affiliation(s)
- Mercedes Barzi
- Department of Cell Death and Proliferation, Institute for Biomedical Research of Barcelona, IIBB-CSIC-IDIBAPS, Barcelona, Spain
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98
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Bijlsma MF, Spek CA. The Hedgehog morphogen in myocardial ischemia-reperfusion injury. Exp Biol Med (Maywood) 2010; 235:447-54. [PMID: 20407076 DOI: 10.1258/ebm.2009.009303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The developmental Hedgehog (Hh) protein family is known to be pivotal in many embryonic patterning events and the number of processes in which Hh plays an essential role is expanding persistently. Recently, it has become clear that the Hh pathway is not only active in the developing embryo but also in the adult organism. For example, Hh has been suggested to salvage ischemia-induced tissue damage although endogenous Hh might be deleterious during the early phase of myocardial ischemia-reperfusion. The current review provides an overview of the history of Hh biology and discusses some novel insights on Hh cell biology. Hh function in pathophysiology as well as recent findings concerning Hh signaling in ischemia models, especially in light of cardiovascular disease, is discussed in more detail and future perspectives are proposed.
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Affiliation(s)
- Maarten F Bijlsma
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
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99
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Hartwig S, Ho J, Pandey P, Macisaac K, Taglienti M, Xiang M, Alterovitz G, Ramoni M, Fraenkel E, Kreidberg JA. Genomic characterization of Wilms' tumor suppressor 1 targets in nephron progenitor cells during kidney development. Development 2010; 137:1189-203. [PMID: 20215353 DOI: 10.1242/dev.045732] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The Wilms' tumor suppressor 1 (WT1) gene encodes a DNA- and RNA-binding protein that plays an essential role in nephron progenitor differentiation during renal development. To identify WT1 target genes that might regulate nephron progenitor differentiation in vivo, we performed chromatin immunoprecipitation (ChIP) coupled to mouse promoter microarray (ChIP-chip) using chromatin prepared from embryonic mouse kidney tissue. We identified 1663 genes bound by WT1, 86% of which contain a previously identified, conserved, high-affinity WT1 binding site. To investigate functional interactions between WT1 and candidate target genes in nephron progenitors, we used a novel, modified WT1 morpholino loss-of-function model in embryonic mouse kidney explants to knock down WT1 expression in nephron progenitors ex vivo. Low doses of WT1 morpholino resulted in reduced WT1 target gene expression specifically in nephron progenitors, whereas high doses of WT1 morpholino arrested kidney explant development and were associated with increased nephron progenitor cell apoptosis, reminiscent of the phenotype observed in Wt1(-/-) embryos. Collectively, our results provide a comprehensive description of endogenous WT1 target genes in nephron progenitor cells in vivo, as well as insights into the transcriptional signaling networks controlled by WT1 that might direct nephron progenitor fate during renal development.
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Affiliation(s)
- Sunny Hartwig
- Department of Medicine, Children's Hospital Boston; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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100
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Shh pathway activation is present and required within the vertebrate limb bud apical ectodermal ridge for normal autopod patterning. Proc Natl Acad Sci U S A 2010; 107:5489-94. [PMID: 20212115 DOI: 10.1073/pnas.0912818107] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Expression of Sonic Hedgehog (Shh) in the posterior mesenchyme of the developing limb bud regulates patterning and growth of the developing limb by activation of the Hedgehog (Hh) signaling pathway. Through the analysis of Shh and Hh signaling target genes, it has been shown that activation in the limb bud mesoderm is required for normal limb development to occur. In contrast, it has been stated that Hh signaling in the limb bud ectoderm cannot occur because components of the Hh signaling pathway and Hh target genes have not been found in this tissue. However, recent array-based data identified both the components necessary to activate the Hh signaling pathway and targets of this pathway in the limb bud ectoderm. Using immunohistochemistry and various methods of detection for targets of Hh signaling, we found that SHH protein and targets of Hh signaling are present in the limb bud ectoderm including the apex of the bud. To directly test whether ectodermal Hh signaling was required for normal limb patterning, we removed Smo, an essential component of the Hh signaling pathway, from the apical ectodermal ridge (AER). Loss of functional Hh signaling in the AER resulted in disruption of the normal digit pattern and formation of additional postaxial cartilaginous condensations. These data indicate that contrary to previous accounts, the Hh signaling pathway is present and required in the developing limb AER for normal autopod development.
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