1
|
Vlashi R, Sun F, Zheng C, Zhang X, Liu J, Chen G. The molecular biology of NF2/Merlin on tumorigenesis and development. FASEB J 2024; 38:e23809. [PMID: 38967126 DOI: 10.1096/fj.202400019rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 06/22/2024] [Accepted: 06/26/2024] [Indexed: 07/06/2024]
Abstract
The neurofibromatosis type 2 (NF2) gene, known for encoding the tumor suppressor protein Merlin, is central to the study of tumorigenesis and associated cellular processes. This review comprehensively examines the multifaceted role of NF2/Merlin, detailing its structural characteristics, functional diversity, and involvement in various signaling pathways such as Wnt/β-catenin, Hippo, TGF-β, RTKs, mTOR, Notch, and Hedgehog. These pathways are crucial for cellular growth, proliferation, and differentiation. NF2 mutations are specifically linked to the development of schwannomas, meningiomas, and ependymomas, although the precise mechanisms of tumor formation in these specific cell types remain unclear. Additionally, the review explores Merlin's role in embryogenesis, highlighting the severe developmental defects and embryonic lethality caused by NF2 deficiency. The potential therapeutic strategies targeting these genetic aberrations are also discussed, emphasizing inhibitors of mTOR, HDAC, and VEGF as promising avenues for treatment. This synthesis of current knowledge underscores the necessity for ongoing research to elucidate the detailed mechanisms of NF2/Merlin and develop effective therapeutic strategies, ultimately aiming to improve the prognosis and quality of life for individuals with NF2 mutations.
Collapse
Affiliation(s)
- Rexhina Vlashi
- College of Life Science and Medicine, Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Fuju Sun
- College of Life Science and Medicine, Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Chenggong Zheng
- College of Life Science and Medicine, Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Xingen Zhang
- Department of Orthopedics, Jiaxing Key Laboratory for Minimally Invasive Surgery in Orthopaedics & Skeletal Regenerative Medicine, Zhejiang Rongjun Hospital, Jiaxing, China
| | - Jie Liu
- Department of Cancer Center, Jiaxing Hospital of Traditional Chinese Medicine, Jiaxing, China
| | - Guiqian Chen
- College of Life Science and Medicine, Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, Zhejiang Sci-Tech University, Hangzhou, China
| |
Collapse
|
2
|
Ali M, Khramushin A, Yadav VK, Schueler-Furman O, Ivarsson Y. Elucidation of Short Linear Motif-Based Interactions of the FERM Domains of Ezrin, Radixin, Moesin, and Merlin. Biochemistry 2023. [PMID: 37224425 DOI: 10.1021/acs.biochem.3c00096] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The ERM (ezrin, radixin, and moesin) family of proteins and the related protein merlin participate in scaffolding and signaling events at the cell cortex. The proteins share an N-terminal FERM [band four-point-one (4.1) ERM] domain composed of three subdomains (F1, F2, and F3) with binding sites for short linear peptide motifs. By screening the FERM domains of the ERMs and merlin against a phage library that displays peptides representing the intrinsically disordered regions of the human proteome, we identified a large number of novel ligands. We determined the affinities for the ERM and merlin FERM domains interacting with 18 peptides and validated interactions with full-length proteins through pull-down experiments. The majority of the peptides contained an apparent Yx[FILV] motif; others show alternative motifs. We defined distinct binding sites for two types of similar but distinct binding motifs (YxV and FYDF) using a combination of Rosetta FlexPepDock computational peptide docking protocols and mutational analysis. We provide a detailed molecular understanding of how the two types of peptides with distinct motifs bind to different sites on the moesin FERM phosphotyrosine binding-like subdomain and uncover interdependencies between the different types of ligands. The study expands the motif-based interactomes of the ERMs and merlin and suggests that the FERM domain acts as a switchable interaction hub.
Collapse
Affiliation(s)
- Muhammad Ali
- Department of Chemistry - BMC, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden
| | - Alisa Khramushin
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Vikash K Yadav
- Department of Chemistry - BMC, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Ylva Ivarsson
- Department of Chemistry - BMC, Uppsala University, Husargatan 3, 751 23 Uppsala, Sweden
| |
Collapse
|
3
|
Ghalavand MA, Asghari A, Farhadi M, Taghizadeh-Hesary F, Garshasbi M, Falah M. The genetic landscape and possible therapeutics of neurofibromatosis type 2. Cancer Cell Int 2023; 23:99. [PMID: 37217995 DOI: 10.1186/s12935-023-02940-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/07/2023] [Indexed: 05/24/2023] Open
Abstract
Neurofibromatosis type 2 (NF2) is a genetic condition marked by the development of multiple benign tumors in the nervous system. The most common tumors associated with NF2 are bilateral vestibular schwannoma, meningioma, and ependymoma. The clinical manifestations of NF2 depend on the site of involvement. Vestibular schwannoma can present with hearing loss, dizziness, and tinnitus, while spinal tumor leads to debilitating pain, muscle weakness, or paresthesias. Clinical diagnosis of NF2 is based on the Manchester criteria, which have been updated in the last decade. NF2 is caused by loss-of-function mutations in the NF2 gene on chromosome 22, leading the merlin protein to malfunction. Over half of NF2 patients have de novo mutations, and half of this group are mosaic. NF2 can be managed by surgery, stereotactic radiosurgery, monoclonal antibody bevacizumab, and close observation. However, the nature of multiple tumors and the necessity of multiple surgeries over the lifetime, inoperable tumors like meningiomatosis with infiltration of the sinus or in the area of the lower cranial nerves, the complications caused by the operation, the malignancies induced by radiotherapy, and inefficiency of cytotoxic chemotherapy due to the benign nature of NF-related tumors have led a march toward exploring targeted therapies. Recent advances in genetics and molecular biology have allowed identifying and targeting of underlying pathways in the pathogenesis of NF2. In this review, we explain the clinicopathological characteristics of NF2, its genetic and molecular background, and the current knowledge and challenges of implementing genetics to develop efficient therapies.
Collapse
Affiliation(s)
- Mohammad Amin Ghalavand
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Alimohamad Asghari
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Skull Base Research Center, The Five Senses Health Institute, Hazrat Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Farhadi
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Farzad Taghizadeh-Hesary
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Radiation Oncology Department, Iran University of Medical Sciences, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Masoumeh Falah
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
4
|
Neogenin suppresses tumor progression and metastasis via inhibiting Merlin/YAP signaling. Cell Death Dis 2023; 9:47. [PMID: 36746934 PMCID: PMC9902585 DOI: 10.1038/s41420-023-01345-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/08/2023]
Abstract
From in situ growth to invasive dissemination is the most lethal attribute of various tumor types. This transition is majorly mediated by the dynamic interplay between two cancer hallmarks, EMT and cell cycle. In this study, we applied nonlinear association analysis in 33 cancer types and found that most signaling receptors simultaneously associating with EMT and cell cycle are potential tumor suppressors. Here we find that a top co-associated receptor, Neogenin (NEO1), inhibits colorectal cancer (CRC) and Glioma in situ growth and metastasis by forming a complex with Merlin (NF2), and subsequent simultaneous promoting the phosphorylation of YAP. Furthermore, Neogenin protein level is associated with good prognosis and correlates with Merlin status in CRC and Glioma. Collectively, our results define Neogenin as a tumor suppressor in CRC and Glioma that acts by restricting oncogenic signaling by the Merlin-YAP pathway, and suggest Neogenin as a candidate therapeutic agent for CRC and Glioma.
Collapse
|
5
|
Hennigan RF, Thomson CS, Stachowski K, Nassar N, Ratner N. Merlin tumor suppressor function is regulated by PIP2-mediated dimerization. PLoS One 2023; 18:e0281876. [PMID: 36809290 PMCID: PMC9942953 DOI: 10.1371/journal.pone.0281876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 01/30/2023] [Indexed: 02/23/2023] Open
Abstract
Neurofibromatosis Type 2 is an inherited disease characterized by Schwann cell tumors of cranial and peripheral nerves. The NF2 gene encodes Merlin, a member of the ERM family consisting of an N-terminal FERM domain, a central α-helical region, and a C-terminal domain. Changes in the intermolecular FERM-CTD interaction allow Merlin to transition between an open, FERM accessible conformation and a closed, FERM-inaccessible conformation, modulating Merlin activity. Merlin has been shown to dimerize, but the regulation and function Merlin dimerization is not clear. We used a nanobody based binding assay to show that Merlin dimerizes via a FERM-FERM interaction, orientated with each C-terminus close to each other. Patient derived and structural mutants show that dimerization controls interactions with specific binding partners, including HIPPO pathway components, and correlates with tumor suppressor activity. Gel filtration experiments showed that dimerization occurs after a PIP2 mediated transition from closed to open conformation monomers. This process requires the first 18 amino acids of the FERM domain and is inhibited by phosphorylation at serine 518. The discovery that active, open conformation Merlin is a dimer represents a new paradigm for Merlin function with implications for the development of therapies designed to compensate for Merlin loss.
Collapse
Affiliation(s)
- Robert F. Hennigan
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
- * E-mail:
| | - Craig S. Thomson
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Kye Stachowski
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Nicolas Nassar
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| | - Nancy Ratner
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States of America
| |
Collapse
|
6
|
Primi MC, Rangarajan ES, Patil DN, Izard T. Conformational flexibility determines the Nf2/merlin tumor suppressor functions. Matrix Biol Plus 2021; 12:100074. [PMID: 34337379 PMCID: PMC8318988 DOI: 10.1016/j.mbplus.2021.100074] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 10/26/2022] Open
Abstract
The Neurofibromatosis type 2 gene encodes the Nf2/merlin tumor suppressor protein that is responsible for the regulation of cell proliferation. Once activated, Nf2/merlin modulates adhesive signaling pathways and thereby inhibits cell growth. Nf2/merlin controls oncogenic gene expression by modulating the Hippo pathway. By responding to several physical and biochemical stimuli, Hippo signaling determines contact inhibition of proliferation as well as organ size. The large tumor suppressor (LATS) serine/threonine-protein kinase is the key enzyme in the highly conserved kinase cascade that negatively regulates the activity and localization of the transcriptional coactivators Yes-associated protein (YAP) and its paralogue transcriptional coactivator with PDZ-binding motif (TAZ). Nf2/merlin belongs to the band 4.1, ezrin, radixin, moesin (FERM) gene family that links the actin cytoskeleton to adherens junctions, remodels adherens junctions during epithelial morphogenesis and maintains organized apical surfaces on the plasma cell membrane. Nf2/merlin and ERM proteins have a globular N-terminal cloverleaf head domain, the FERM domain, that binds to the plasma membrane, a central α-helical domain, and a tail domain that binds to its head domain. Here we present the high-resolution crystal structure of Nf2/merlin bound to LATS1 which shows that LATS1 binding to Nf2/merlin displaces the Nf2/merlin tail domain and causes an allosteric shift in the Nf2/merlin α-helix that extends from its FERM domain. This is consistent with the fact that full-length Nf2/merlin binds LATS1 ~10-fold weaker compared to LATS1 binding to the Nf2/merlin-PIP2 complex. Our data increase our understanding of Nf2/merlin biology by providing mechanistic insights into the Hippo pathway that are relevant to several diseases in particular oncogenic features that are associated with cancers.
Collapse
Affiliation(s)
- Marina C Primi
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Erumbi S Rangarajan
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Dipak N Patil
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| |
Collapse
|
7
|
Khayenko V, Maric HM. Targeting GABA AR-Associated Proteins: New Modulators, Labels and Concepts. Front Mol Neurosci 2019; 12:162. [PMID: 31293385 PMCID: PMC6606717 DOI: 10.3389/fnmol.2019.00162] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022] Open
Abstract
γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review article, we introduce a new strategy to modulate GABAeric signaling: targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with submicron resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.
Collapse
Affiliation(s)
- Vladimir Khayenko
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Hans Michael Maric
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| |
Collapse
|
8
|
Michie KA, Bermeister A, Robertson NO, Goodchild SC, Curmi PMG. Two Sides of the Coin: Ezrin/Radixin/Moesin and Merlin Control Membrane Structure and Contact Inhibition. Int J Mol Sci 2019; 20:ijms20081996. [PMID: 31018575 PMCID: PMC6515277 DOI: 10.3390/ijms20081996] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/16/2019] [Accepted: 04/19/2019] [Indexed: 12/21/2022] Open
Abstract
The merlin-ERM (ezrin, radixin, moesin) family of proteins plays a central role in linking the cellular membranes to the cortical actin cytoskeleton. Merlin regulates contact inhibition and is an integral part of cell–cell junctions, while ERM proteins, ezrin, radixin and moesin, assist in the formation and maintenance of specialized plasma membrane structures and membrane vesicle structures. These two protein families share a common evolutionary history, having arisen and separated via gene duplication near the origin of metazoa. During approximately 0.5 billion years of evolution, the merlin and ERM family proteins have maintained both sequence and structural conservation to an extraordinary level. Comparing crystal structures of merlin-ERM proteins and their complexes, a picture emerges of the merlin-ERM proteins acting as switchable interaction hubs, assembling protein complexes on cellular membranes and linking them to the actin cytoskeleton. Given the high level of structural conservation between the merlin and ERM family proteins we speculate that they may function together.
Collapse
Affiliation(s)
- Katharine A Michie
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Adam Bermeister
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Neil O Robertson
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Sophia C Goodchild
- Department of Molecular Sciences, Macquarie University, Sydney 2109, Australia.
| | - Paul M G Curmi
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| |
Collapse
|
9
|
Chen H, Dai J. miR-409-3p suppresses the proliferation, invasion and migration of tongue squamous cell carcinoma via targeting RDX. Oncol Lett 2018; 16:543-551. [PMID: 29928443 DOI: 10.3892/ol.2018.8687] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 12/22/2017] [Indexed: 12/16/2022] Open
Abstract
The aim of the present study is to investigate the role of microRNA (miRNA/miR)-409-3p in the proliferation, invasion and migration of tongue squamous cell carcinoma (TSCC) cells via targeting radixin (RDX) gene. The expression of miR-409-3p was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in TSCC tissue and cell lines. The binding of miR-409-3p to RDX was investigated by performing a dual-luciferase reporter gene assay. Tca8113 cells were selected to transfect with miR-409-3p mimic/inhibitor, small interfering (si)-RDX, and miR-409-3p inhibitor + si-RDX, as well as negative control (NC) respectively. The proliferative, migratory and invasive abilities of transfected Tca8113 cells were investigated by cell-counting-kit-8, wound-healing and Transwell assays, respectively. Additionally, a tumor xenograft model was constructed to examine the effects of miR-409-3p on the tumor growth and lymphatic metastasis in nude mice. A significant downregulation was detected in miR-409-3p expression in TSCC tissues and cells (all P<0.05) compared with normal tongue mucosa tissues and cell line, which was associated with lymph node metastasis and tumor-node metastasis staging (both P<0.05). The results from the dual-luciferase reporter gene assay indicated that RDX is a potential target gene of miR-409-3p. Compared with the blank group, a marked reduction in RDX expression, cell proliferation, migration and invasion was detected in the miR-409-3p mimic group and si-RDX group (all P<0.05). Conversely, the reverse was observed in cells that were transfected with the miR-409-3p inhibitor. Furthermore, si-RDX is able to reverse the effect of miR-409-3p inhibitor on cell proliferation, invasion and migration (all P<0.05). The results form the tumor xenograft model of nude mice verified that miR-409-3p mimic is able to inhibit the growth of Tca8113 tumor cells and lymph node metastasis in nude mice. miR-409-3p may delay the proliferation of TSCC cells by inhibiting of RDX so as to decrease its migratory and invasive abilities. Therefore, miR-409-3p may be a potential target for the clinical treatment of TSCC.
Collapse
Affiliation(s)
- Hujie Chen
- Department of Stomatology, Jingzhou Central Hospital, The Second Clinical Medical College, Yangtze University, Jingzhou, Hubei 434000, P.R. China
| | - Jing Dai
- Department of Stomatology, Jingzhou Central Hospital, The Second Clinical Medical College, Yangtze University, Jingzhou, Hubei 434000, P.R. China
| |
Collapse
|
10
|
Cairns L, Tran T, Kavran JM. Structural Insights into the Regulation of Hippo Signaling. ACS Chem Biol 2017; 12:601-610. [PMID: 28150487 DOI: 10.1021/acschembio.6b01058] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
During development, the Hippo pathway regulates the balance between cell proliferation and apoptosis to control organ size. Appropriate Hippo signaling is associated with stem cell maintenance, while inappropriate signaling can result in tumorigenesis and cancer. Cellular and genetic investigations have identified core components and determined that complex formation and protein phosphorylation are crucial regulatory events. The recent spate of high-resolution structures of Hippo pathway components have begun to reveal the molecular mechanisms controlling these events, including the molecular determinates of complex formation between YAP and TEAD, the role of phosphorylation in controlling complex formation by Mob, and the conformational changes accompanying Mst1/2 kinase domain activation. We will review these advances and revisit previous structures to provide a comprehensive overview of the structural changes associated with the regulation of this pathway as well as discuss areas that could benefit from further mechanistic studies.
Collapse
Affiliation(s)
- Leah Cairns
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Thao Tran
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Jennifer M. Kavran
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
| |
Collapse
|
11
|
Vasilyeva NA, Murzina GB, Kireev II, Pivovarov AS. Influence of Membrane Receptor Lateral Diffusion on the Short-Term Depression of Acetylcholine-Induced Current in Helix Neurons. Cell Mol Neurobiol 2017; 37:1443-1455. [PMID: 28236056 DOI: 10.1007/s10571-017-0475-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/16/2017] [Indexed: 11/29/2022]
Abstract
We have studied how various drugs increasing the rate of nicotinic acetylcholine receptors (nAChRs) lateral diffusion affect the depression of ACh-induced current in land snail Helix lucorum neurons responsible for defensive behavior. The acetylcholine (ACh) iontophoretic application protocol imitated the behavioral habituation protocol for the intact animal. We found that the drugs decreasing cholesterol level in cell membranes as methyl-β-cyclodextrin 1 mM and Ro 48-8071 2 µM, and polyclonal antibodies to actin-binding proteins as spectrin 5 µg/ml and merlin 2.5 µg/ml have changed the dynamic of ACh-current depression. The nAChRs lateral diffusion coefficient was obtained by fluorescence recovery after photobleaching. A curve fitting model specially created for analysis of short-term choline sensitivity depression in snail neurons helped us evaluate separately the contribution of nAChRs lateral diffusion, their endocytosis and exocytosis to observed effects during electrophysiological experiments. Taken together, we hypothesize that nAChRs lateral diffusion plays an important role in the cellular correlate of habituation in land snail Helix lucorum neurons.
Collapse
Affiliation(s)
- Natalia A Vasilyeva
- Department of Higher Nervous Activity, Lomonosov Moscow State University, Leninskie Gory, 1, building 12, Moscow, Russia, 119234.,Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova, 5a, Moscow, Russia, 117485
| | - Galina B Murzina
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova, 5a, Moscow, Russia, 117485
| | - Igor I Kireev
- A.N.Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 1, building 40, Moscow, Russia, 119234
| | - Arkady S Pivovarov
- Department of Higher Nervous Activity, Lomonosov Moscow State University, Leninskie Gory, 1, building 12, Moscow, Russia, 119234.
| |
Collapse
|
12
|
Boratkó A, Péter M, Csortos C. Regulation of merlin by protein phosphatase 1-TIMAP and EBP50 in endothelial cells. Int J Biochem Cell Biol 2016; 82:10-17. [PMID: 27871951 DOI: 10.1016/j.biocel.2016.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/18/2016] [Accepted: 11/14/2016] [Indexed: 11/16/2022]
Abstract
Merlin (moesin-ezrin-radixin like protein), the product of neurofibromatosis type 2 gene, was primarily recognized as a tumor suppressor, but it also functions as a membrane-cytoskeletal linker and regulator of multiple signaling pathways. The activity and localization of merlin is regulated by head to tail folding that is controlled by phosphorylation of the Ser518 side chain. Merlin localizes in the nucleus when the Ser518 side chain is not phosphorylated, while the phosphorylated form is present in the cytoplasm and the plasma membrane. In this work interactions and their impact on the subcellular localization and phosphorylation state of the Ser518 side chain of merlin were investigated in endothelial cells. It is shown that merlin (dephospho-Ser518 form) interacts in the nucleus of endothelial cells with the scaffolding protein EBP50, a member of the Na+/H+exchanger regulatory factor family. Upon EBP50 depletion, merlin translocated from the nucleus, suggesting that binding of merlin to EBP50 is critical in the nuclear localization of merlin. Along with the translocation, the phosphorylation level of phospho-Ser518-merlin was increased in EBP50 depleted cells. TIMAP (TGFβ-inhibited membrane-associated protein), a type 1 protein phosphatase (PP1) regulatory subunit, was newly recognized as an interacting partner for merlin. Domain mapping using truncated mutant forms in GST pull down revealed that the N-terminal half of TIMAP (aa 1-290) and the FERM domain of merlin are the regions responsible for the interaction.The catalytic subunit of PP1 (PP1c) was present in all merlin-TIMAP pull down or immunoprecipitation samples demonstrating that merlin actually interacts with the PP1c-TIMAP holoenzyme. On the other hand, from TIMAP depleted cells, without its targeting protein, PP1c could not bind to merlin. Also, when the phosphatase activity of PP1c-TIMAP was inhibited either with depletion of TIMAP or by treatment of the cells with specific PP1 inhibitor, there was an increase in the amount of phospho-Ser518 form of merlin in the membrane of the cells. These data strongly suggest that the PP1c-TIMAP- complex dephosphorylates phospho-Ser518-merlin. ECIS measurements indicate that phospho-merlin accelerates in vitro wound healing of the endothelial monolayer. In conclusion, in endothelial cells, EBP50 is required for the nuclear localization of merlin and the PP1c-TIMAP holoenzyme plays an important role in the dephosphorylation of merlin on its Ser518 side chain, which influence cell migration and proliferation.
Collapse
Affiliation(s)
- Anita Boratkó
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1., Debrecen H-4032, Hungary
| | - Margit Péter
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1., Debrecen H-4032, Hungary
| | - Csilla Csortos
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1., Debrecen H-4032, Hungary.
| |
Collapse
|
13
|
Characterization of Clinical Cases of Collecting Duct Carcinoma of the Kidney Assessed by Comprehensive Genomic Profiling. Eur Urol 2016; 70:516-21. [DOI: 10.1016/j.eururo.2015.06.019] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/14/2015] [Indexed: 02/08/2023]
|
14
|
Gungor-Ordueri NE, Celik-Ozenci C, Cheng CY. Ezrin: a regulator of actin microfilaments in cell junctions of the rat testis. Asian J Androl 2016; 17:653-8. [PMID: 25652626 PMCID: PMC4492059 DOI: 10.4103/1008-682x.146103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ezrin, radixin, moesin and merlin (ERM) proteins are highly homologous actin-binding proteins that share extensive sequence similarity with each other. These proteins tether integral membrane proteins and their cytoplasmic peripheral proteins (e.g., adaptors, nonreceptor protein kinases and phosphatases) to the microfilaments of actin-based cytoskeleton. Thus, these proteins are crucial to confer integrity of the apical membrane domain and its associated junctional complex, namely the tight junction and the adherens junction. Since ectoplasmic specialization (ES) is an F-actin-rich testis-specific anchoring junction-a highly dynamic ultrastructure in the seminiferous epithelium due to continuous transport of germ cells, in particular spermatids, across the epithelium during the epithelial cycle-it is conceivable that ERM proteins are playing an active role in these events. Although these proteins were first reported almost 25 years and have since been extensively studied in multiple epithelia/endothelia, few reports are found in the literature to examine their role in the actin filament bundles at the ES. Studies have shown that ezrin is also a constituent protein of the actin-based tunneling nanotubes (TNT) also known as intercellular bridges, which are transient cytoplasmic tubular ultrastructures that transport signals, molecules and even organelles between adjacent and distant cells in an epithelium to coordinate cell events that occur across an epithelium. Herein, we critically evaluate recent data on ERM in light of recent findings in the field in particular ezrin regarding its role in actin dynamics at the ES in the testis, illustrating additional studies are warranted to examine its physiological significance in spermatogenesis.
Collapse
Affiliation(s)
| | | | - C Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, USA
| |
Collapse
|
15
|
Petrilli AM, Fernández-Valle C. Role of Merlin/NF2 inactivation in tumor biology. Oncogene 2016; 35:537-48. [PMID: 25893302 PMCID: PMC4615258 DOI: 10.1038/onc.2015.125] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 02/20/2015] [Accepted: 03/16/2015] [Indexed: 01/13/2023]
Abstract
Merlin (Moesin-ezrin-radixin-like protein, also known as schwannomin) is a tumor suppressor protein encoded by the neurofibromatosis type 2 gene NF2. Loss of function mutations or deletions in NF2 cause neurofibromatosis type 2 (NF2), a multiple tumor forming disease of the nervous system. NF2 is characterized by the development of bilateral vestibular schwannomas. Patients with NF2 can also develop schwannomas on other cranial and peripheral nerves, as well as meningiomas and ependymomas. The only potential treatment is surgery/radiosurgery, which often results in loss of function of the involved nerve. There is an urgent need for chemotherapies that slow or eliminate tumors and prevent their formation in NF2 patients. Interestingly NF2 mutations and merlin inactivation also occur in spontaneous schwannomas and meningiomas, as well as other types of cancer including mesothelioma, glioma multiforme, breast, colorectal, skin, clear cell renal cell carcinoma, hepatic and prostate cancer. Except for malignant mesotheliomas, the role of NF2 mutation or inactivation has not received much attention in cancer, and NF2 might be relevant for prognosis and future chemotherapeutic approaches. This review discusses the influence of merlin loss of function in NF2-related tumors and common human cancers. We also discuss the NF2 gene status and merlin signaling pathways affected in the different tumor types and the molecular mechanisms that lead to tumorigenesis, progression and pharmacological resistance.
Collapse
Affiliation(s)
- Alejandra M. Petrilli
- Department of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Cristina Fernández-Valle
- Department of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| |
Collapse
|
16
|
Martin CL, Singh SM. Identification, modeling, and characterization studies of Tetrahymena thermophila myosin FERM domains suggests a conserved core fold but functional differences. Cytoskeleton (Hoboken) 2015; 72:585-96. [PMID: 26492945 DOI: 10.1002/cm.21261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 10/16/2015] [Accepted: 10/19/2015] [Indexed: 11/05/2022]
Abstract
Myosins (MYO) define a superfamily of motor proteins which facilitate movement along cytoskeletal actin filaments in an ATP-dependent manner. To date, over 30 classes of myosin have been defined that vary in their roles and distribution across different taxa. The multidomain tail of myosin is responsible for the observed functional differences in different myosin classes facilitating differential binding to different cargos. One domain found in this region, the FERM domain, is found in several diverse proteins and is involved in many biological functions ranging from cell adhesion and actin-driven cytoskeleton assembly to cell signaling. Recently, new classes of unconventional myosin have been identified in Tetrahymena thermophila. In this study, we have identified, modeled, and characterized eight FERM domains from the unconventional T. thermophila myosins as their complete functional MyTH4-FERM cassettes. Our results reveal notable sequence, structural, and electrostatic differences between T. thermophila and other characterized FERM domains. Specifically, T. thermophila FERM domains contain helical inserts or extensions, which contribute to significant differences in surface electrostatic profiles of T. thermophila myosin FERMs when compared to the conventional FERM domains. Analyses of the modeled domains reveal differences in key functional residues as well as phosphoinositide-binding signatures and affinities. The work presented here broadens the scope of our understanding of myosin classes and their inherent functions, and provides a platform for experimentalists to design rational experimental studies to test the functional roles for T. thermophila myosins.
Collapse
Affiliation(s)
- Che L Martin
- Biology Department, the Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York, 10016
| | - Shaneen M Singh
- Biology Department, the Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York, 10016.,Department of Biology, Brooklyn College of the City University of New York, 2900 Bedford Ave. Brooklyn, New York, 11210, USA
| |
Collapse
|
17
|
Tracing the evolution of FERM domain of Kindlins. Mol Phylogenet Evol 2014; 80:193-204. [DOI: 10.1016/j.ympev.2014.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 07/31/2014] [Accepted: 08/08/2014] [Indexed: 01/25/2023]
|
18
|
Abeysundara N, Leung AC, Primrose DA, Hughes SC. Regulation of cell proliferation and adhesion by means of a novel region of drosophila merlin interacting with Sip1. Dev Dyn 2014; 243:1554-70. [DOI: 10.1002/dvdy.24187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 08/08/2014] [Accepted: 09/03/2014] [Indexed: 01/22/2023] Open
Affiliation(s)
- Namal Abeysundara
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - Albert C. Leung
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - David A. Primrose
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - Sarah C. Hughes
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| |
Collapse
|
19
|
Ali Khajeh J, Ju JH, Atchiba M, Allaire M, Stanley C, Heller WT, Callaway DJE, Bu Z. Molecular conformation of the full-length tumor suppressor NF2/Merlin--a small-angle neutron scattering study. J Mol Biol 2014; 426:2755-68. [PMID: 24882693 PMCID: PMC4407695 DOI: 10.1016/j.jmb.2014.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/11/2014] [Accepted: 05/13/2014] [Indexed: 12/26/2022]
Abstract
The tumor suppressor protein Merlin inhibits cell proliferation upon establishing cell-cell contacts. Because Merlin has high level of sequence similarity to the Ezrin-Radixin-Moesin family of proteins, the structural model of Ezrin-Radixin-Moesin protein autoinhibition and cycling between closed/resting and open/active conformational states is often employed to explain Merlin function. However, recent biochemical studies suggest alternative molecular models of Merlin function. Here, we have determined the low-resolution molecular structure and binding activity of Merlin and a Merlin(S518D) mutant that mimics the inactivating phosphorylation at S518 using small-angle neutron scattering and binding experiments. Small-angle neutron scattering shows that, in solution, both Merlin and Merlin(S518D) adopt a closed conformation, but binding experiments indicate that a significant fraction of either Merlin or Merlin(S518D) is capable of binding to the target protein NHERF1. Upon binding to the phosphatidylinositol 4,5-bisphosphate lipid, the wild-type Merlin adopts a more open conformation than in solution, but Merlin(S518D) remains in a closed conformation. This study supports a rheostat model of Merlin in NHERF1 binding and contributes to resolving a controversy about the molecular conformation and binding activity of Merlin.
Collapse
Affiliation(s)
- Jahan Ali Khajeh
- Department of Chemistry, City College of New York and CUNY Graduate Center, NY, USA
| | - Jeong Ho Ju
- Department of Chemistry, City College of New York and CUNY Graduate Center, NY, USA
| | - Moussoubaou Atchiba
- Department of Chemistry, City College of New York and CUNY Graduate Center, NY, USA
| | - Marc Allaire
- Photon Sciences Directorate, Brookhaven National Laboratory, NY, USA
| | | | - William T Heller
- Biology and Soft Matter Division, Oak Ridge National Laboratory, TN, USA
| | - David J E Callaway
- Department of Chemistry, City College of New York and CUNY Graduate Center, NY, USA
| | - Zimei Bu
- Department of Chemistry, City College of New York and CUNY Graduate Center, NY, USA.
| |
Collapse
|
20
|
Zemmoura I, Vourc'h P, Paubel A, Parfait B, Cohen J, Bilan F, Kitzis A, Rousselot C, Parker F, François P, Andres CR. A deletion causing NF2 exon 9 skipping is associated with familial autosomal dominant intramedullary ependymoma. Neuro Oncol 2013; 16:250-5. [PMID: 24357459 DOI: 10.1093/neuonc/not165] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Intramedullary ependymomas are rare and benign tumors in the adult. Little is known about their physiopathology, but the implication of the NF2 gene is suspected because of their presence in a third of patients with type 2 neurofibromatosis (NF2), a disorder caused by mutation of the NF2 gene. METHODS We conducted a clinical and genetic study of a family in which 5 of 9 members suffered from intramedullary ependymoma. Karyotyping and CGH array analysis were performed on DNA from peripheral blood lymphocytes from affected participants. The NF2 gene sequences were then determined in DNA from 3 nonaffected and all 5 affected members of the family. RESULTS Karyotype and CGH array findings were normal. Sequencing of NF2 revealed a heterozygous deletion, c.811-39_841del69bp, at the intron 8/exon 9 junction, in all affected members that was absent from all nonaffected members. RT-PCR analysis and sequencing revealed a novel NF2 transcript characterized by a skipping of exon 9 (75 bp). This deletion is predicted to result in a 25-amino acid deletion in the N-terminal FERM domain of neurofibromin 2. Modeling of this mutant domain suggests possible disorganization of the subdomain C. CONCLUSION We report the first family with an NF2 mutation associated with intramedullary ependymomas without other features of NF2 syndrome. This mutation, which has not been described previously, may particularly affect the function of neurofibromin 2 in ependymocytes leading to the development of intramedullary WHO grade II ependymomas. We propose that sporadic intramedullary ependymomas should also be analyzed for this region of NF2 gene.
Collapse
Affiliation(s)
- Ilyess Zemmoura
- Corresponding author: Ilyess Zemmoura, MD, Service de Neurochirurgie, CHRU Bretonneau, 2 boulevard Tonnellé, 37004, Tours Cedex, France.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Laulajainen M, Melikova M, Muranen T, Carpén O, Grönholm M. Distinct overlapping sequences at the carboxy-terminus of merlin regulate its tumour suppressor and morphogenic activity. J Cell Mol Med 2013; 16:2161-75. [PMID: 22325036 PMCID: PMC3822986 DOI: 10.1111/j.1582-4934.2012.01525.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The Neurofibromatosis 2 (NF2) gene product merlin is a tumour suppressor, which in addition to inhibiting cell proliferation regulates cell morphology. The morphogenic properties of merlin may play a role in tumour suppression, as patient-derived tumour cells demonstrate cytoskeletal abnormalities. However, it is still unclear how these functions are linked. The N-terminal FERM-domain of merlin is highly homologous to the oncogenic protein ezrin, while the C-termini are less conserved, suggesting that the opposite effect of the proteins on proliferation could be mediated by their distinct C-terminal regions. In this study we characterize the role of the most C-terminal residues of merlin in the regulation of proliferation, cytoskeletal organization, phosphorylation and intramolecular associations. In addition to the two full-length merlin isoforms and truncating mutations found in patients, we focused on the evolutionally conserved C-terminal residues 545-547, also harbouring disease-causing mutations. We demonstrate that merlin induces cell extensions, which result from impaired retraction of protrusions rather than from increased formation of filopodia. The residues 538-568 were found particularly important for this morphogenic activity. The results further show that both merlin isoforms are able to equally inhibit proliferation, whereas C-terminal mutants affecting residues 545-547 are less effective in growth suppression. This study demonstrates that the C-terminus contains distinct but overlapping functional domains important for regulation of the morphogenic activity, intramolecular associations and cell proliferation.
Collapse
Affiliation(s)
- Minja Laulajainen
- Biomedicum Helsinki, Department of Pathology, University of Helsinki, Helsinki, Finland.
| | | | | | | | | |
Collapse
|
22
|
Wisotzkey RG, Konikoff CE, Newfeld SJ. Hippo pathway phylogenetics predicts monoubiquitylation of Salvador and Merlin/Nf2. PLoS One 2012; 7:e51599. [PMID: 23272121 PMCID: PMC3522738 DOI: 10.1371/journal.pone.0051599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 11/08/2012] [Indexed: 01/20/2023] Open
Abstract
Recently we employed phylogenetics to predict that the cellular interpretation of TGF-β signals is modulated by monoubiquitylation cycles affecting the Smad4 signal transducer/tumor suppressor. This prediction was subsequently validated by experiments in flies, frogs and mammalian cells. Here we apply a phylogenetic approach to the Hippo pathway and predict that two of its signal transducers, Salvador and Merlin/Nf2 (also a tumor suppressor) are regulated by monoubiquitylation. This regulatory mechanism does not lead to protein degradation but instead serves as a highly efficient “off/on” switch when the protein is subsequently deubiquitylated. Overall, our study shows that the creative application of phylogenetics can predict new roles for pathway components and new mechanisms for regulating intercellular signaling pathways.
Collapse
Affiliation(s)
| | - Charlotte E. Konikoff
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Stuart J. Newfeld
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- * E-mail:
| |
Collapse
|
23
|
Manetti ME, Geden S, Bott M, Sparrow N, Lambert S, Fernandez-Valle C. Stability of the tumor suppressor merlin depends on its ability to bind paxillin LD3 and associate with β1 integrin and actin at the plasma membrane. Biol Open 2012; 1:949-57. [PMID: 23213372 PMCID: PMC3507182 DOI: 10.1242/bio.20122121] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/27/2012] [Indexed: 01/03/2023] Open
Abstract
The NF2 gene encodes a tumor suppressor protein known as merlin or schwannomin whose loss of function causes Neurofibromatosis Type 2 (NF2). NF2 is characterized by the development of benign tumors, predominantly schwannomas, in the peripheral nervous system. Merlin links plasma membrane receptors with the actin cytoskeleton and its targeting to the plasma membrane depends on direct binding to the paxillin scaffold protein. Exon 2 of NF2, an exon mutated in NF2 patients and deleted in a mouse model of NF2, encodes the merlin paxillin binding domain (PBD1). Here, we sought to determine the role of PBD1 in regulation of merlin stability and association with plasma membrane receptors and the actin cytoskeleton in Schwann cells. Using a fluorescence-based pulse-chase technique, we measured the half-life of Halo-tagged merlin variants carrying PBD1, exon 2, and exons 2 and 3 deletions in transiently transfected Schwann cells. We found that PBD1 alone was necessary and sufficient to increase merlin's half-life from approximately three to eleven hours. Merlin lacking PBD1 did not form a complex with surface β1 integrins or associate with the actin cytoskeleton. In addition, direct binding studies using purified merlin and paxillin domains revealed that merlin directly binds paxillin LD3 (leucine-aspartate 3) domain as well as the LD4 and LD5 domains. Together these results demonstrate that a direct interaction between merlin PBD1 and the paxillin LD3-5 domains targets merlin to the plasma membrane where it is stabilized by its association with surface β1 integrins and cortical actin.
Collapse
Affiliation(s)
- Maria Elisa Manetti
- Burnett School of Biomedical Science, College of Medicine, University of Central Florida, Health Science Campus , 6900 Lake Nona Boulevard, Orlando, FL 32827 , USA
| | | | | | | | | | | |
Collapse
|
24
|
Morrow KA, Shevde LA. Merlin: the wizard requires protein stability to function as a tumor suppressor. Biochim Biophys Acta Rev Cancer 2012; 1826:400-6. [PMID: 22750751 DOI: 10.1016/j.bbcan.2012.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 11/27/2022]
Abstract
Neurofibromatosis type 2 (NF2), characterized by tumors of the nervous system, is a result of functional loss of the NF2 gene. The NF2 gene encodes Merlin (moesin-ezrin-radixin-like protein), an ERM (Ezrin, Radixin, Moesin) protein family member. Merlin functions as a tumor suppressor through impacting mechanisms related to proliferation, apoptosis, survival, motility, adhesion, and invasion. Several studies have summarized the tumor intrinsic mutations in Merlin. Given the fact that tumor cells are not in isolation, but rather in an intricate, mutually sustaining synergy with their surrounding stroma, the dialog between the tumor cells and the stroma can potentially impact the molecular homeostasis and promote evolution of the malignant phenotype. This review summarizes the epigenetic modifications, transcript stability, and post-translational modifications that impact Merlin. We have reviewed the role of extrinsic factors originating from the tumor milieu that influence the availability of Merlin inside the cell. Information regarding Merlin regulation could lead to novel therapeutics by stabilizing Merlin protein in tumors that have reduced Merlin protein expression without displaying any NF2 genetic alterations.
Collapse
Affiliation(s)
- K Adam Morrow
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | | |
Collapse
|