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Khan F, Khan S, Rana N, Rahim T, Arshad A, Khan I, Ogaly HA, Ahmed DAEM, Dera AA, Zaib S. Mutational analysis of consanguineous families and their targeted therapy against dwarfism. J Biomol Struct Dyn 2024:1-18. [PMID: 38321911 DOI: 10.1080/07391102.2024.2307446] [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: 04/18/2023] [Accepted: 01/09/2024] [Indexed: 02/08/2024]
Abstract
Dwarfism is a medical term used to describe individuals with a height-vertex measurement that falls below two standard deviations (-2SD) or the third percentile for their gender and age. Normal development of growth is a complicated dynamic procedure that depends upon the coordination of different aspects involving diet, genetics, and biological aspects like hormones in equilibrium. Any severe or acute pathologic procedure may disturb the individual's normal rate of growth. In this research, we examined four (A-D) Pakistani consanguineous families that exhibited syndromic dwarfism, which was inherited in an autosomal recessive pattern. The genomic DNA of each family member was extracted by using phenol-chloroform and Kit methods. Whole Exome Sequencing (WES) of affected family members (IV-11, III-5, IV-4 and III-13) from each group was performed at the Department of Medical Genetics, University of Antwerp, Belgium. After filtering the exome data, the mutations in PPM1F, FGFR3, ERCC2, and PCNT genes were determined by Sanger sequencing of each gene by using specific primers. Afterward, FGFR3 was found to be a suitable drug target among all the mutations to treat achondroplasia also known as disproportionate dwarfism. BioSolveIT softwares were used to discover the lead active inhibitory molecule against FGFR3. This research will not only provide short knowledge to the concerned pediatricians, researchers, and family physicians for the preliminary assessment and management of the disorder but also provide a lead inhibitor for the treatment of disproportionate dwarfism.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Feroz Khan
- Department of Zoology Wild Life and Fishries, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan
| | - Sarmir Khan
- Center of Reproductive Medicine, Henan Key Laboratory of Reproduction and Genetics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Nehal Rana
- Department of Basic and Applied Chemistry, Faculty of Science and Technology, University of Central Punjab, Lahore, Pakistan
| | - Tariq Rahim
- Department of Biosciences, COMSATS University, Islamabad, Pakistan
| | - Abida Arshad
- Department of Zoology Wild Life and Fishries, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan
| | - Imtiaz Khan
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom
| | - Hanan A Ogaly
- Chemistry Department, College of Science, King Khalid University, Abha, Saudi Arabia
| | | | - Ayed A Dera
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Sumera Zaib
- Department of Basic and Applied Chemistry, Faculty of Science and Technology, University of Central Punjab, Lahore, Pakistan
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2
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Hartl I, Brumovska V, Striedner Y, Yasari A, Schütz GJ, Sevcsik E, Tiemann-Boege I. Measurement of FGFR3 signaling at the cell membrane via total internal reflection fluorescence microscopy to compare the activation of FGFR3 mutants. J Biol Chem 2023; 299:102832. [PMID: 36581204 PMCID: PMC9900515 DOI: 10.1016/j.jbc.2022.102832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/28/2022] Open
Abstract
Fibroblast growth factor receptors (FGFRs) initiate signal transduction via the RAS/mitogen-activated protein kinase pathway by their tyrosine kinase activation known to determine cell growth, tissue differentiation, and apoptosis. Recently, many missense mutations have been reported for FGFR3, but we only know the functional effect for a handful of them. Some mutations result in aberrant FGFR3 signaling and are associated with various genetic disorders and oncogenic conditions. Here, we employed micropatterned surfaces to specifically enrich fluorophore-tagged FGFR3 (monomeric GFP [mGFP]-FGFR3) in certain areas of the plasma membrane of living cells. We quantified receptor activation via total internal reflection fluorescence microscopy of FGFR3 signaling at the cell membrane that captured the recruitment of the downstream signal transducer growth factor receptor-bound 2 (GRB2) tagged with mScarlet (GRB2-mScarlet) to FGFR3 micropatterns. With this system, we tested the activation of FGFR3 upon ligand addition (fgf1 and fgf2) for WT and four FGFR3 mutants associated with congenital disorders (G380R, Y373C, K650Q, and K650E). Our data showed that ligand addition increased GRB2 recruitment to WT FGFR3, with fgf1 having a stronger effect than fgf2. For all mutants, we found an increased basal receptor activity, and only for two of the four mutants (G380R and K650Q), activity was further increased upon ligand addition. Compared with previous reports, two mutant receptors (K650Q and K650E) had either an unexpectedly high or low activation state, respectively. This can be attributed to the different methodology, since micropatterning specifically captures signaling events at the plasma membrane. Collectively, our results provide further insight into the functional effects of mutations to FGFR3.
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Affiliation(s)
- Ingrid Hartl
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | | | - Yasmin Striedner
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | - Atena Yasari
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | | | - Eva Sevcsik
- Insitute of Applied Physics, TU Wien, Vienna, Austria.
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3
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Pesl M, Verescakova H, Skutkova L, Strenkova J, Krejci P. A registry of achondroplasia: a 6-year experience from the Czechia and Slovak Republic. Orphanet J Rare Dis 2022; 17:229. [PMID: 35710503 PMCID: PMC9205086 DOI: 10.1186/s13023-022-02374-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 05/29/2022] [Indexed: 11/20/2022] Open
Abstract
Background Achondroplasia (ACH) is one of the most prevalent genetic forms of short-limbed skeletal dysplasia, caused by gain-of-function mutations in the receptor tyrosine kinase FGFR3. In August 2021, the C-type natriuretic peptide (CNP) analog vosoritide was approved for the treatment of ACH. A total of six other inhibitors of FGFR3 signaling are currently undergoing clinical evaluation for ACH. This progress creates an opportunity for children with ACH, who may gain early access to the treatment by entering clinical trials before the closure of their epiphyseal growth plates and cessation of growth. Pathophysiology associated with the ACH, however, demands a long observational period before admission to the interventional trial. Public patient registries can facilitate the process by identification of patients suitable for treatment and collecting the data necessary for the trial entry.
Results In 2015, we established the prospective ACH registry in the Czechia and the Slovak Republic (http://www.achondroplasia-registry.cz). Patient data is collected through pediatric practitioners and other relevant specialists. After informed consent is given, the data is entered to the online TrialDB system and stored in the Oracle 9i database. The initial cohort included 51 ACH children (average age 8.5 years, range 3 months to 14 years). The frequency of selected neurological, orthopedic, or ORL diagnoses is also recorded. In 2015–2021, a total of 89 measurements of heights, weights, and other parameters were collected. The individual average growth rate was calculated and showed values without exception in the lower decile for the appropriate age. Evidence of paternal age effect was found, with 58.7% of ACH fathers older than the general average paternal age and 43.5% of fathers older by two or more years. One ACH patient had orthopedic limb extension and one patient received growth hormone therapy. Low blood pressure or renal impairment were not found in any patient. Conclusion The registry collected the clinical information of 51 pediatric ACH patients during its 6 years of existence, corresponding to ~ 60% of ACH patients living in the Czechia and Slovak Republic. The registry continues to collect ACH patient data with annual frequency to monitor the growth and other parameters in preparation for future therapy. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02374-x.
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Affiliation(s)
- Martin Pesl
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne University Hospital, Brno, Czech Republic.,1st Department of Internal Medicine, Cardioangiology, St. Anne University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Hana Verescakova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Linda Skutkova
- Department of Pediatrics, University Hospital Brno, Brno, Czech Republic
| | - Jana Strenkova
- Institute of Biostatistics and Analyses, Masaryk University, Brno, Czech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic. .,International Clinical Research Center, St. Anne University Hospital, Brno, Czech Republic. .,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Brno, Czech Republic.
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Expanding horizons of achondroplasia treatment: current options and future developments. Osteoarthritis Cartilage 2022; 30:535-544. [PMID: 34864168 DOI: 10.1016/j.joca.2021.11.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/23/2021] [Accepted: 11/28/2021] [Indexed: 02/02/2023]
Abstract
Activating mutations in the FGFR3 receptor tyrosine kinase lead to most prevalent form of genetic dwarfism in humans, the achondroplasia. Many features of the complex function of FGFR3 in growing skeleton were characterized, which facilitated identification of therapy targets, and drove progress toward treatment. In August 2021, the vosoritide was approved for treatment of achondroplasia, which is based on a stable variant of the C-natriuretic peptide. Other drugs may soon follow, as several conceptually different inhibitors of FGFR3 signaling progress through clinical trials. Here, we review the current achondroplasia therapeutics, describe their mechanisms, and illuminate motivations leading to their development. We also discuss perspectives of curing achondroplasia, and options for repurposing achondroplasia drugs for dwarfing conditions unrelated to FGFR3.
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Pfeiffer KM, Brod M, Smith A, Viuff D, Ota S, Charlton RW. Functioning and well-being in older children and adolescents with achondroplasia: A qualitative study. Am J Med Genet A 2021; 188:454-462. [PMID: 34643322 PMCID: PMC9291880 DOI: 10.1002/ajmg.a.62534] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 08/31/2021] [Accepted: 09/25/2021] [Indexed: 11/29/2022]
Abstract
The study aimed to explore how having achondroplasia affects older children and adolescents' day‐to‐day functioning and well‐being. Individual/focus group interviews were conducted with older children/adolescents between the ages of 9 to <18 years and diagnosed with achondroplasia to elicit key concepts. An adapted grounded theory approach informed the qualitative analysis of interview data. Thirty‐two children and adolescents completed interviews. Study results revealed five impact domains, including physical health, functioning, school impacts, emotional well‐being, and social well‐being. Frequently reported impacts on physical health included low stamina/tiring easily (81%) and back pain (69%). Key impacts in the functioning domain were difficulty with reaching objects or high places (84%) and walking long distances (75%). Emotional impacts included feeling different (63%), worried/scared (47%), and embarrassed/self‐conscious (47%). Impacts on social well‐being included difficulty with sports or physical play (81%) and others treating child as younger than their actual age (75%). The most frequent school impact was trouble participating in physical education (81%). A preliminary theoretical model depicting the experiences of older children/adolescents with achondroplasia was constructed based on the analysis. The preliminary theoretical model of older children and adolescents' experiences of living with achondroplasia may be used to inform future research and clinical practice.
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Affiliation(s)
| | - Meryl Brod
- The Brod Group, Mill Valley, California, USA
| | - Alden Smith
- Ascendis Pharma, Inc., Palo Alto, California, USA
| | | | - Sho Ota
- Ascendis Pharma, Inc., Palo Alto, California, USA
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6
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Ergoren MC, Eren E, Manara E, Paolacci S, Tulay P, Sag SO, Bertelli M, Mocan G, Temel SG. Psychomotor Delay in a Child with FGFR3 G380R Pathogenic Mutation Causing Achondroplasia. Glob Med Genet 2021; 8:100-103. [PMID: 34430961 PMCID: PMC8378917 DOI: 10.1055/s-0041-1725070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Achondroplasia (ACH) is a hereditary disorder of dwarfism that is caused by the aberrant proliferation and differentiation of chondrocyte growth plates. The common findings of macrocephaly and facial anomalies accompany dwarfism in these patients.
Fibroblast growth factor receptor 3
(
FGFR3
) gene mutations are common causes of achondroplasia. The current study presents a case of 2-year-old male child patient presenting with phenotypic characteristics of ACH. The interesting finding of the case is the presence of psychomotor delay that is not very common in these patients. Clinical exome sequencing analyzing 4.813 disease causing genes revealed a de novo c.1138G > A mutation within the
FGFR3
gene. In conclusion, the mutation confirms the clinical diagnosis of ACH, and it seems to be causing the psychomotor delay in this patient.
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Affiliation(s)
- Mahmut C Ergoren
- Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Erdal Eren
- Department of Pediatric Endocrinology, Faculty of Medicine, Bursa Uludağ University, Bursa, Turkey
| | | | | | - Pinar Tulay
- Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Sebnem O Sag
- Department of Medical Genetics, Faculty of Medicine, Bursa Uludag University, Bursa, Turkey
| | | | - Gamze Mocan
- Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Sehime Gulsun Temel
- Department of Medical Genetics, Faculty of Medicine, Bursa Uludag University, Bursa, Turkey.,Department of Histology and Embryology, Faculty of Medicine, Bursa Uludag University, Bursa, Turkey
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7
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Pfeiffer KM, Brod M, Smith A, Viuff D, Ota S, Charlton RW. A qualitative study of the impacts of having an infant or young child with achondroplasia on parent well-being. Orphanet J Rare Dis 2021; 16:351. [PMID: 34362417 PMCID: PMC8344208 DOI: 10.1186/s13023-021-01978-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 07/25/2021] [Indexed: 11/26/2022] Open
Abstract
Background Currently, there is limited research on how having a child diagnosed with achondroplasia affects parents’ lives. The purpose of the study was to investigate the experiences of parents of infants and young children less than two years of age with achondroplasia. Methods Concept elicitation interviews were conducted with parents of children less than 2 years of age with achondroplasia in the United States and Spain. Using grounded theory methods modified for health outcomes research, a qualitative analysis of interview transcripts was conducted. Based on the qualitative analysis, a preliminary theoretical model of the experiences of parents of infants and young children with achondroplasia was developed. Results Fifteen parents, including 14 mothers and 1 father from 15 unique families, participated in individual or focus group concept elicitation interviews in the US (n = 9) and Spain (n = 6). The qualitative analysis identified four key parent impact domains, which included caretaking responsibilities, impacts on emotional well-being, having worries and concerns about their child, and impacts on daily well-being. Frequently discussed caretaking responsibilities among parents were managing child’s medical care/treatment (93%), obtaining adaptations/items for child (73%), and monitoring child to avoid complications of achondroplasia (67%). Emotional impacts included feeling stressed/overwhelmed (67%), depressed/sad (40%), and anxious/nervous (33%). Worries and concerns included worry/concern about the future (100%), concerns regarding child’s physical health (87%), worry about child’s social well-being (80%), concern for child’s emotional well-being (73%), and worry about child being able to function independently (67%). Daily well-being impacts included family strain (60%), missed work time (47%), and missed/limited social activities (33%). Based on the qualitative findings, a preliminary theoretical model depicting the experiences of parents of infants and young children with achondroplasia was created. Conclusions The study sheds light on the range of impacts that parents of infants and young children with achondroplasia may experience, including caretaking responsibilities, impacts on emotional well-being, worries/concerns regarding their child, and impacts on daily well-being. The theoretical model of parent experiences may provide a helpful framework for informing future research and clinical practice.
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Affiliation(s)
| | - Meryl Brod
- The Brod Group, 219 Julia Ave., Mill Valley, CA, 94941, USA.
| | | | | | - Sho Ota
- Ascendis Pharma, Inc., Palo Alto, CA, USA
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Kimura T, Bosakova M, Nonaka Y, Hruba E, Yasuda K, Futakawa S, Kubota T, Fafilek B, Gregor T, Abraham SP, Gomolkova R, Belaskova S, Pesl M, Csukasi F, Duran I, Fujiwara M, Kavkova M, Zikmund T, Kaiser J, Buchtova M, Krakow D, Nakamura Y, Ozono K, Krejci P. An RNA aptamer restores defective bone growth in FGFR3-related skeletal dysplasia in mice. Sci Transl Med 2021; 13:13/592/eaba4226. [PMID: 33952673 DOI: 10.1126/scitranslmed.aba4226] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 12/30/2020] [Accepted: 04/16/2021] [Indexed: 01/04/2023]
Abstract
Achondroplasia is the most prevalent genetic form of dwarfism in humans and is caused by activating mutations in FGFR3 tyrosine kinase. The clinical need for a safe and effective inhibitor of FGFR3 is unmet, leaving achondroplasia currently incurable. Here, we evaluated RBM-007, an RNA aptamer previously developed to neutralize the FGFR3 ligand FGF2, for its activity against FGFR3. In cultured rat chondrocytes or mouse embryonal tibia organ culture, RBM-007 rescued the proliferation arrest, degradation of cartilaginous extracellular matrix, premature senescence, and impaired hypertrophic differentiation induced by FGFR3 signaling. In cartilage xenografts derived from induced pluripotent stem cells from individuals with achondroplasia, RBM-007 rescued impaired chondrocyte differentiation and maturation. When delivered by subcutaneous injection, RBM-007 restored defective skeletal growth in a mouse model of achondroplasia. We thus demonstrate a ligand-trap concept of targeting the cartilage FGFR3 and delineate a potential therapeutic approach for achondroplasia and other FGFR3-related skeletal dysplasias.
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Affiliation(s)
- Takeshi Kimura
- Department of Pediatrics, Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan
| | - Michaela Bosakova
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic.,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic
| | | | - Eva Hruba
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic
| | - Kie Yasuda
- Department of Pediatrics, Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan
| | | | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic.,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic
| | - Tomas Gregor
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic
| | - Sara P Abraham
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic
| | - Regina Gomolkova
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic
| | - Silvie Belaskova
- International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic
| | - Martin Pesl
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic.,First Department of Internal Medicine-Cardioangiology, St. Anne's University Hospital, Masaryk University, 65691 Brno, Czech Republic
| | - Fabiana Csukasi
- Department of Orthopaedic Surgery, University of California Los Angeles, Los Angeles, CA 90095, USA.,Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN)-LABRET, University of Málaga, IBIMA-BIONAND, 29071 Málaga, Spain
| | - Ivan Duran
- Department of Orthopaedic Surgery, University of California Los Angeles, Los Angeles, CA 90095, USA.,Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN)-LABRET, University of Málaga, IBIMA-BIONAND, 29071 Málaga, Spain
| | | | - Michaela Kavkova
- Central European Institute of Technology, Brno University of Technology, 61200 Brno, Czech Republic
| | - Tomas Zikmund
- Central European Institute of Technology, Brno University of Technology, 61200 Brno, Czech Republic
| | - Josef Kaiser
- Central European Institute of Technology, Brno University of Technology, 61200 Brno, Czech Republic
| | - Marcela Buchtova
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | - Deborah Krakow
- Department of Orthopaedic Surgery, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yoshikazu Nakamura
- RIBOMIC Inc., Tokyo 108-0071, Japan. .,Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan.
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500 Brno, Czech Republic. .,International Clinical Research Center, St. Anne's University Hospital, 65691 Brno, Czech Republic.,Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 60200 Brno, Czech Republic
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9
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Nakamura Y. Multiple Therapeutic Applications of RBM-007, an Anti-FGF2 Aptamer. Cells 2021; 10:cells10071617. [PMID: 34203430 PMCID: PMC8305614 DOI: 10.3390/cells10071617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 12/12/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) plays a pivotal role in angiogenesis, but is not the only player with an angiogenic function. Fibroblast growth factor-2 (FGF2), which was discovered before VEGF, is also an angiogenic growth factor. It has been shown that FGF2 plays positive pathophysiological roles in tissue remodeling, bone health, and regeneration, such as the repair of neuronal damage, skin wound healing, joint protection, and the control of hypertension. Targeting FGF2 as a therapeutic tool in disease treatment through clinically useful inhibitors has not been developed until recently. An isolated inhibitory RNA aptamer against FGF2, named RBM-007, has followed an extensive preclinical study, with two clinical trials in phase 2 and phase 1, respectively, underway to assess the therapeutic impact in age-related macular degeneration (wet AMD) and achondroplasia (ACH), respectively. Moreover, showing broad therapeutic potential, preclinical evidence supports the use of RBM-007 in the treatment of lung cancer and cancer pain.
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Affiliation(s)
- Yoshikazu Nakamura
- Division of RNA Medical Science, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan;
- RIBOMIC Inc., Tokyo 108-0071, Japan
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10
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Paul MD, Grubb HN, Hristova K. Quantifying the strength of heterointeractions among receptor tyrosine kinases from different subfamilies: Implications for cell signaling. J Biol Chem 2020; 295:9917-9933. [PMID: 32467228 PMCID: PMC7380177 DOI: 10.1074/jbc.ra120.013639] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/20/2020] [Indexed: 01/09/2023] Open
Abstract
Receptor tyrosine kinases (RTKs) are single-pass membrane proteins that control vital cell processes such as cell growth, survival, and differentiation. There is a growing body of evidence that RTKs from different subfamilies can interact and that these diverse interactions can have important biological consequences. However, these heterointeractions are often ignored, and their strengths are unknown. In this work, we studied the heterointeractions of nine RTK pairs, epidermal growth factor receptor (EGFR)-EPH receptor A2 (EPHA2), EGFR-vascular endothelial growth factor receptor 2 (VEGFR2), EPHA2-VEGFR2, EPHA2-fibroblast growth factor receptor 1 (FGFR1), EPHA2-FGFR2, EPHA2-FGFR3, VEGFR2-FGFR1, VEGFR2-FGFR2, and VEGFR2-FGFR3, using a FRET-based method. Surprisingly, we found that RTK heterodimerization and homodimerization strengths can be similar, underscoring the significance of RTK heterointeractions in signaling. We discuss how these heterointeractions can contribute to the complexity of RTK signal transduction, and we highlight the utility of quantitative FRET for probing multiple interactions in the plasma membrane.
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Affiliation(s)
- Michael D Paul
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Hana N Grubb
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Kalina Hristova
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
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11
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Paul MD, Hristova K. The transition model of RTK activation: A quantitative framework for understanding RTK signaling and RTK modulator activity. Cytokine Growth Factor Rev 2019; 49:23-31. [PMID: 31711797 DOI: 10.1016/j.cytogfr.2019.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 10/10/2019] [Indexed: 01/15/2023]
Abstract
Here, we discuss the transition model of receptor tyrosine kinase (RTK) activation, which is derived from biophysical investigations of RTK interactions and signaling. The model postulates that (1) RTKs can interact laterally to form dimers even in the absence of ligand, (2) different unliganded RTK dimers have different stabilities, (3) ligand binding stabilizes the RTK dimers, and (4) ligand binding causes structural changes in the RTK dimer. The model is grounded in the principles of physical chemistry and provides a framework to understand RTK activity and to make predictions in quantitative terms. It can guide basic research aimed at uncovering the mechanism of RTK activation and, in the long run, can empower the search for modulators of RTK function.
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Affiliation(s)
- Michael D Paul
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218, United States
| | - Kalina Hristova
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, 21218, United States.
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12
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Abstract
Receptor tyrosine kinases (RTKs) play important roles in cell growth, motility, differentiation, and survival. These single-pass membrane proteins are grouped into subfamilies based on the similarity of their extracellular domains. They are generally thought to be activated by ligand binding, which promotes homodimerization and then autophosphorylation in trans. However, RTK interactions are more complicated, as RTKs can interact in the absence of ligand and heterodimerize within and across subfamilies. Here, we review the known cross-subfamily RTK heterointeractions and their possible biological implications, as well as the methodologies which have been used to study them. Moreover, we demonstrate how thermodynamic models can be used to study RTKs and to explain many of the complicated biological effects which have been described in the literature. Finally, we discuss the concept of the RTK interactome: a putative, extensive network of interactions between the RTKs. This RTK interactome can produce unique signaling outputs; can amplify, inhibit, and modify signaling; and can allow for signaling backups. The existence of the RTK interactome could provide an explanation for the irreproducibility of experimental data from different studies and for the failure of some RTK inhibitors to produce the desired therapeutic effects. We argue that a deeper knowledge of RTK interactome thermodynamics can lead to a better understanding of fundamental RTK signaling processes in health and disease. We further argue that there is a need for quantitative, thermodynamic studies that probe the strengths of the interactions between RTKs and their ligands and between different RTKs.
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Affiliation(s)
- Michael D. Paul
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore MD 21218
| | - Kalina Hristova
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore MD 21218
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Ajmal M, Mir A, Shoaib M, Malik SA, Nasir M. Identification and in silico characterization of p.G380R substitution in FGFR3, associated with achondroplasia in a non-consanguineous Pakistani family. Diagn Pathol 2017; 12:47. [PMID: 28679403 PMCID: PMC5499044 DOI: 10.1186/s13000-017-0642-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 06/29/2017] [Indexed: 12/03/2022] Open
Abstract
Background The dimerization efficiency of FGFR3 transmembrane domain plays a critical role in the formation of a normal skeleton through the negative regulation of bone development. Recently, gain-of-function mutations in the transmembrane domain of FGFR3 has been described associated with an aberrant negative regulation, leading to the development of achondroplasia-group disorders, including achondroplasia (ACH), hypochondroplasia (HCH) and thanatophoric dysplasia (TD). Here, we describe a non-consanguineous Pakistani family with achondroplasia to explain hereditary basis of the disease. Methods PCR-based linkage analysis using microsatellite markers was employed to localize the disease gene. Gene specific intronic primers were used to amplify the genomic DNA from all affected as well as phenotypically healthy individuals. Amplified PCR products were then subjected to Sanger sequencing and RFLP analysis to identify a potentially pathogenic mutation. The impact of identified mutation on FGFR3 protein’s structure and stability was highlighted through different bioinformatics tools. Results Genetic screening of the family revealed a previously reported heterozygous c.1138 G > A (p.G380R) mutation in the coding exon 8 of FGFR3 gene. Identified genetic variation was confirmed in all affected individuals while healthy individuals and controls were found genotypically normal. The results were further validated by RFLP analysis as c.1138 G > A substitution generates a unique recognition site for SfcI endonuclease. Following SfcI digestion, the electrophoretic pattern of three bands/DNA fragments for each patient is indicative of heterozygous status of the disease allele. In silico studies of the mutant FGFR3 protein predicted to adversely affect the stability of FGFR3 protein. Conclusions Mutation in the transmembrane domain may adversely affect the dimerization efficiency and overall stability of the FGFR3, leading to a constitutively active protein. As a result, an uncontrolled intracellular signaling or negative bone growth regulation leads to achondroplasia. Our findings support the fact that p.G380R is a common mutation among diverse population of the world and like other countries, can be used as a molecular diagnosis marker for achondroplasia in Pakistan. Electronic supplementary material The online version of this article (doi:10.1186/s13000-017-0642-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Muhammad Ajmal
- Institute of Biomedical and Genetic Engineering, 24-Mauve area, G-9/1, Islamabad, 44000, Pakistan
| | - Asif Mir
- Department of Biotechnology, International Islamic University, Islamabad, Pakistan
| | - Muhammad Shoaib
- KRL General Hospital, Orthopedic Department, 24-Mauve area, G-9/1, Islamabad, 44000, Pakistan
| | - Salman Akbar Malik
- Department of Biochemistry, Quaid-i-Azam University, Islamabad, 44000, Pakistan
| | - Muhammad Nasir
- Institute of Biomedical and Genetic Engineering, 24-Mauve area, G-9/1, Islamabad, 44000, Pakistan.
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14
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Sarabipour S, Hristova K. Pathogenic Cysteine Removal Mutations in FGFR Extracellular Domains Stabilize Receptor Dimers and Perturb the TM Dimer Structure. J Mol Biol 2016; 428:3903-3910. [PMID: 27596331 DOI: 10.1016/j.jmb.2016.08.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/02/2016] [Accepted: 08/25/2016] [Indexed: 12/14/2022]
Abstract
Missense mutations that introduce or remove cysteine residues in receptor tyrosine kinases are believed to cause pathologies by stabilizing the active receptor tyrosine kinase dimers. However, the magnitude of this stabilizing effect has not been measured for full-length receptors. Here, we characterize the dimer stabilities of three full-length fibroblast growth factor receptor (FGFR) mutants harboring pathogenic cysteine substitutions: the C178S FGFR1 mutant, the C342R FGFR2 mutant, and the C228R FGFR3 mutant. We find that the three mutations stabilize the FGFR dimers. We further see that the mutations alter the configuration of the FGFR transmembrane dimers. Thus, both aberrant dimerization and perturbed dimer structure likely contribute to the pathological phenotypes arising due to these mutations.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, USA
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, USA.
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15
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Helsten T, Schwaederle M, Kurzrock R. Fibroblast growth factor receptor signaling in hereditary and neoplastic disease: biologic and clinical implications. Cancer Metastasis Rev 2016. [PMID: 26224133 PMCID: PMC4573649 DOI: 10.1007/s10555-015-9579-8] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fibroblast growth factors (FGFs) and their receptors (FGFRs) are transmembrane growth factor receptors with wide tissue distribution. FGF/FGFR signaling is involved in neoplastic behavior and also development, differentiation, growth, and survival. FGFR germline mutations (activating) can cause skeletal disorders, primarily dwarfism (generally mutations in FGFR3), and craniofacial malformation syndromes (usually mutations in FGFR1 and FGFR2); intriguingly, some of these activating FGFR mutations are also seen in human cancers. FGF/FGFR aberrations reported in cancers are mainly thought to be gain-of-function changes, and several cancers have high frequencies of FGFR alterations, including breast, bladder, or squamous cell carcinomas (lung and head and neck). FGF ligand aberrations (predominantly gene amplifications) are also frequently seen in cancers, in contrast to hereditary syndromes. There are several pharmacologic agents that have been or are being developed for inhibition of FGFR/FGF signaling. These include both highly selective inhibitors as well as multi-kinase inhibitors. Of note, only four agents (ponatinib, pazopanib, regorafenib, and recently lenvatinib) are FDA-approved for use in cancer, although the approval was not based on their activity against FGFR. Perturbations in the FGFR/FGF signaling are present in both inherited and malignant diseases. The development of potent inhibitors targeting FGF/FGFR may provide new tools against disorders caused by FGF/FGFR alterations.
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Affiliation(s)
- Teresa Helsten
- Center for Personalized Cancer Therapy and Division of Hematology and Oncology, University of California San Diego, Moores Cancer Center, 3855 Health Sciences Drive, MC #0658, La Jolla, CA, 92093-0658, USA.
| | - Maria Schwaederle
- Center for Personalized Cancer Therapy and Division of Hematology and Oncology, University of California San Diego, Moores Cancer Center, 3855 Health Sciences Drive, MC #0658, La Jolla, CA, 92093-0658, USA.
| | - Razelle Kurzrock
- Center for Personalized Cancer Therapy and Division of Hematology and Oncology, University of California San Diego, Moores Cancer Center, 3855 Health Sciences Drive, MC #0658, La Jolla, CA, 92093-0658, USA
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16
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Sarabipour S, Hristova K. Effect of the achondroplasia mutation on FGFR3 dimerization and FGFR3 structural response to fgf1 and fgf2: A quantitative FRET study in osmotically derived plasma membrane vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:1436-42. [PMID: 27040652 PMCID: PMC4870120 DOI: 10.1016/j.bbamem.2016.03.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/15/2016] [Accepted: 03/29/2016] [Indexed: 11/20/2022]
Abstract
The G380R mutation in the transmembrane domain of FGFR3 is a germline mutation responsible for most cases of Achondroplasia, a common form of human dwarfism. Here we use quantitative Fӧster Resonance Energy Transfer (FRET) and osmotically derived plasma membrane vesicles to study the effect of the achondroplasia mutation on the early stages of FGFR3 signaling in response to the ligands fgf1 and fgf2. Using a methodology that allows us to capture structural changes on the cytoplasmic side of the membrane in response to ligand binding to the extracellular domain of FGFR3, we observe no measurable effects of the G380R mutation on FGFR3 ligand-bound dimer configurations. Instead, the most notable effect of the achondroplasia mutation is increased propensity for FGFR3 dimerization in the absence of ligand. This work reveals new information about the molecular events that underlie the achondroplasia phenotype, and highlights differences in FGFR3 activation due to different single amino-acid pathogenic mutations.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, United States
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
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17
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Sarabipour S, Hristova K. Mechanism of FGF receptor dimerization and activation. Nat Commun 2016; 7:10262. [PMID: 26725515 PMCID: PMC4725768 DOI: 10.1038/ncomms10262] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/23/2015] [Indexed: 12/21/2022] Open
Abstract
Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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18
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Sarabipour S, Hristova K. FGFR3 unliganded dimer stabilization by the juxtamembrane domain. J Mol Biol 2015; 427:1705-14. [PMID: 25688803 PMCID: PMC4380549 DOI: 10.1016/j.jmb.2015.02.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/12/2015] [Accepted: 02/11/2015] [Indexed: 11/22/2022]
Abstract
Receptor tyrosine kinases (RTKs) conduct biochemical signals upon dimerization in the membrane plane. While RTKs are generally known to be activated in response to ligand binding, many of these receptors are capable of forming unliganded dimers that are likely important intermediates in the signaling process. All 58 RTKs consist of an extracellular (EC) domain, a transmembrane (TM) domain, and an intracellular domain that includes a juxtamembrane (JM) sequence and a kinase domain. Here we investigate directly the effect of the JM domain on unliganded dimer stability of FGFR3, a receptor that is critically important for skeletal development. The data suggest that FGFR3 unliganded dimers are stabilized by receptor-receptor contacts that involve the JM domains. The contribution is significant, as it is similar in magnitude to the stabilizing contribution of a pathogenic mutation and the repulsive contribution of the EC domain. Furthermore, we show that the effects of the JM domain and a TM pathogenic mutation on unliganded FGFR3 dimer stability are additive. We observe that the JM-mediated dimer stabilization occurs when the JM domain is linked to FGFR3 TM domain and not simply anchored to the plasma membrane. These results point to a coordinated stabilization of the unliganded dimeric state of FGFR3 by its JM and TM domains via a mechanism that is distinctly different from the case of another well studied receptor, EGFR.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, USA
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, USA.
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19
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Sarabipour S, Chan RB, Zhou B, Di Paolo G, Hristova K. Analytical characterization of plasma membrane-derived vesicles produced via osmotic and chemical vesiculation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1591-8. [PMID: 25896659 DOI: 10.1016/j.bbamem.2015.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 04/02/2015] [Accepted: 04/06/2015] [Indexed: 10/23/2022]
Abstract
Plasma membrane-derived vesicles are being used in biophysical and biochemical research as a simple, yet native-like model of the cellular membrane. Here we report on the characterization of vesicles produced via two different vesiculation methods from CHO and A431 cell lines. The first method is a recently developed method which utilizes chloride salts to induce osmotic vesiculation. The second is a well established chemical vesiculation method which uses DTT and formaldehyde. We show that both vesiculation methods produce vesicles which contain the lipid species previously reported in the plasma membrane of these cell lines. The two methods lead to small but statistically significant differences in two lipid species only; phosphatidylcholine (PC) and plasmalogen phosphatidylethanolamine (PEp). However, highly significant differences were observed in the degree of incorporation of a membrane receptor and in the degree of retention of soluble cytosolic proteins within the vesicles.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Sciences and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robin B Chan
- Department of Pathology and Cell Biology, Columbia University Medical Center, Columbia University, New York, NY 10032, USA
| | - Bowen Zhou
- Department of Pathology and Cell Biology, Columbia University Medical Center, Columbia University, New York, NY 10032, USA
| | - Gilbert Di Paolo
- Department of Pathology and Cell Biology, Columbia University Medical Center, Columbia University, New York, NY 10032, USA
| | - Kalina Hristova
- Department of Materials Sciences and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
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20
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He L, Hristova K. Quantification of the effects of mutations on receptor tyrosine kinase (RTK) activation in mammalian cells. Methods Mol Biol 2014; 1233:81-7. [PMID: 25319891 DOI: 10.1007/978-1-4939-1789-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Single amino acid mutations in receptor tyrosine kinases (RTKs) are known to cause receptor over-activation and disease. Here we present a detailed protocol for the quantification of the effect of mutations on RTK activation in mammalian cells. The activation measurements are based on Western blotting, and involve direct comparison of receptor phosphorylation under conditions that ensure identical expression of wild-type and mutant receptors.
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Affiliation(s)
- Lijuan He
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA
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21
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Qi H, Jin M, Duan Y, Du X, Zhang Y, Ren F, Wang Y, Tian Q, Wang X, Wang Q, Zhu Y, Xie Y, Liu C, Cao X, Mishina Y, Chen D, Deng CX, Chang Z, Chen L. FGFR3 induces degradation of BMP type I receptor to regulate skeletal development. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1237-47. [PMID: 24657641 DOI: 10.1016/j.bbamcr.2014.03.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/16/2014] [Accepted: 03/12/2014] [Indexed: 01/04/2023]
Abstract
Fibroblast growth factors (FGFs) and their receptors (FGFRs) play significant roles in vertebrate organogenesis and morphogenesis. FGFR3 is a negative regulator of chondrogenesis and multiple mutations with constitutive activity of FGFR3 result in achondroplasia, one of the most common dwarfisms in humans, but the molecular mechanism remains elusive. In this study, we found that chondrocyte-specific deletion of BMP type I receptor a (Bmpr1a) rescued the bone overgrowth phenotype observed in Fgfr3 deficient mice by reducing chondrocyte differentiation. Consistently, using in vitro chondrogenic differentiation assay system, we demonstrated that FGFR3 inhibited BMPR1a-mediated chondrogenic differentiation. Furthermore, we showed that FGFR3 hyper-activation resulted in impaired BMP signaling in chondrocytes of mouse growth plates. We also found that FGFR3 inhibited BMP-2- or constitutively activated BMPR1-induced phosphorylation of Smads through a mechanism independent of its tyrosine kinase activity. We found that FGFR3 facilitates BMPR1a to degradation through Smurf1-mediated ubiquitination pathway. We demonstrated that down-regulation of BMP signaling by BMPR1 inhibitor dorsomorphin led to the retardation of chondrogenic differentiation, which mimics the effect of FGF-2 on chondrocytes and BMP-2 treatment partially rescued the retarded growth of cultured bone rudiments from thanatophoric dysplasia type II mice. Our findings reveal that FGFR3 promotes the degradation of BMPR1a, which plays an important role in the pathogenesis of FGFR3-related skeletal dysplasia.
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Affiliation(s)
- Huabing Qi
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Min Jin
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Yaqi Duan
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Xiaolan Du
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China; State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing 400042, China
| | - Yuanquan Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Fangli Ren
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Yinyin Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Qingyun Tian
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA; Department of Orthopaedic Surgery, New York University School of Medicine and NYU Hospital for Joint Diseases, New York, NY 10003, USA
| | - Xiaofeng Wang
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Quan Wang
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Ying Zhu
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Yangli Xie
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Chuanju Liu
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA; Department of Orthopaedic Surgery, New York University School of Medicine and NYU Hospital for Joint Diseases, New York, NY 10003, USA
| | - Xu Cao
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yuji Mishina
- Department of Biologic & Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Di Chen
- Department of Biochemistry, Rush University, Chicago, IL 60612, USA
| | - Chu-xia Deng
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 10/9N105, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhijie Chang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Lin Chen
- Center of Bone Metabolism and Repair (CBMR), Trauma Center, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China; State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing 400042, China; Department of Rehabilitation Medicine, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China.
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22
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Sarabipour S, Hristova K. FGFR3 transmembrane domain interactions persist in the presence of its extracellular domain. Biophys J 2014; 105:165-71. [PMID: 23823235 DOI: 10.1016/j.bpj.2013.05.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/17/2013] [Accepted: 05/31/2013] [Indexed: 01/30/2023] Open
Abstract
Isolated receptor tyrosine kinase transmembrane (TM) domains have been shown to form sequence-specific dimers in membranes. Yet, it is not clear whether studies of isolated TM domains yield knowledge that is relevant to full-length receptors or whether the large glycosylated extracellular domains alter the interactions between the TM helices. Here, we address this question by quantifying the effect of the pathogenic A391E TM domain mutation on the stability of the fibroblast growth factor receptor 3 dimer in the presence of the extracellular domain and comparing these results to the case of the isolated TM fibroblast growth factor receptor 3 domains. We perform the measurements in plasma membrane-derived vesicles using a Förster-resonance-energy-transfer-based method. The effect of the mutation on dimer stability in both cases is the same (∼-1.5 kcal/mol), suggesting that the interactions observed in simple TM-peptide model systems are relevant in a biological context.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Sciences and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
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23
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Bessenyei B, Nagy A, Balogh E, Novák L, Bognár L, Knegt AC, Oláh E. Achondroplasia with multiple-suture craniosynostosis: a report of a new case of this rare association. Am J Med Genet A 2013; 161A:2641-4. [PMID: 23949953 DOI: 10.1002/ajmg.a.36130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 06/06/2013] [Indexed: 11/07/2022]
Abstract
We report on a female patient with an exceedingly rare combination of achondroplasia and multiple-suture craniosynostosis. Besides the specific features of achondroplasia, synostosis of the metopic, coronal, lambdoid, and squamosal sutures was found. Series of neurosurgical interventions were carried out, principally for acrocephaly and posterior plagiocephaly. The most common achondroplasia mutation, a p.Gly380Arg in the fibroblast growth factor receptor 3 (FGFR3) gene, was detected. Cytogenetic and array CGH analyses, as well as molecular genetic testing of FGFR1, 2, 3 and TWIST1 genes failed to identify any additional genetic alteration. It is suggested that this unusual phenotype is a result of variable expressivity of the common achondroplasia mutation.
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Affiliation(s)
- Beáta Bessenyei
- Clinical Genetic Center, Department of Pediatrics, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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24
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Collet C, Alessandri JL, Arnaud E, Balu M, Daire V, Di Rocco F. Crouzon syndrome and Bent bone dysplasia associated with mutations at the same Tyr-381 residue inFGFR2gene. Clin Genet 2013; 85:598-9. [DOI: 10.1111/cge.12213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/17/2013] [Accepted: 05/30/2013] [Indexed: 11/30/2022]
Affiliation(s)
- C. Collet
- Service de Biochimie et Biologie Moléculaire; Hôpital Lariboisière; Paris France
| | - J.-L. Alessandri
- Service de Réanimation Pédiatrique; Hôpital Felix Guyon, CHU de la réunion; Saint Denis-La Réunion France
| | - E. Arnaud
- Unité de Chirurgie Craniofaciale, Service de Neurochirurgie; Centre de Référence National Dysostoses Crâniofaciales, Hôpital Necker; Paris France
| | - M. Balu
- Service de Radiologie Pédiatrique; Hôpital Felix Guyon, CHU de la réunion; Saint Denis-La Réunion France
| | - V.C. Daire
- Génétique Clinique, INSERM U781; Université Paris-Descartes-Sorbonne Paris cité, Institut Imagine, Hôpital Necker; Paris France
| | - F. Di Rocco
- Unité de Chirurgie Craniofaciale, Service de Neurochirurgie; Centre de Référence National Dysostoses Crâniofaciales, Hôpital Necker; Paris France
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25
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Shinde DN, Elmer DP, Calabrese P, Boulanger J, Arnheim N, Tiemann-Boege I. New evidence for positive selection helps explain the paternal age effect observed in achondroplasia. Hum Mol Genet 2013; 22:4117-26. [PMID: 23740942 PMCID: PMC3781639 DOI: 10.1093/hmg/ddt260] [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] [Indexed: 02/07/2023] Open
Abstract
There are certain de novo germline mutations associated with genetic disorders whose mutation rates per generation are orders of magnitude higher than the genome average. Moreover, these mutations occur exclusively in the male germ line and older men have a higher probability of having an affected child than younger ones, known as the paternal age effect (PAE). The classic example of a genetic disorder exhibiting a PAE is achondroplasia, caused predominantly by a single-nucleotide substitution (c.1138G>A) in FGFR3. To elucidate what mechanisms might be driving the high frequency of this mutation in the male germline, we examined the spatial distribution of the c.1138G>A substitution in a testis from an 80-year-old unaffected man. Using a technology based on bead-emulsion amplification, we were able to measure mutation frequencies in 192 individual pieces of the dissected testis with a false-positive rate lower than 2.7 × 10−6. We observed that most mutations are clustered in a few pieces with 95% of all mutations occurring in 27% of the total testis. Using computational simulations, we rejected the model proposing an elevated mutation rate per cell division at this nucleotide site. Instead, we determined that the observed mutation distribution fits a germline selection model, where mutant spermatogonial stem cells have a proliferative advantage over unmutated cells. Combined with data on several other PAE mutations, our results support the idea that the PAE, associated with a number of Mendelian disorders, may be explained primarily by a selective mechanism.
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Affiliation(s)
- Deepali N Shinde
- The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors
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Chen F, Sarabipour S, Hristova K. Multiple consequences of a single amino acid pathogenic RTK mutation: the A391E mutation in FGFR3. PLoS One 2013; 8:e56521. [PMID: 23437153 PMCID: PMC3577887 DOI: 10.1371/journal.pone.0056521] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 01/12/2013] [Indexed: 12/30/2022] Open
Abstract
The A391E mutation in fibroblast growth factor receptor 3 (FGFR3) is the genetic cause for Crouzon syndrome with Acanthosis Nigricans. Here we investigate the effect of this mutation on FGFR3 activation in HEK 293 T cells over a wide range of fibroblast growth factor 1 concentrations using a physical-chemical approach that deconvolutes the effects of the mutation on dimerization, ligand binding, and efficiency of phosphorylation. It is believed that the mutation increases FGFR3 dimerization, and our results verify this. However, our results also demonstrate that the increase in dimerization is not the sole effect of the mutation, as the mutation also facilitates the phosphorylation of critical tyrosines in the activation loop of FGFR3. The activation of mutant FGFR3 is substantially increased due to a combination of these two effects. The low expression of the mutant, however, attenuates its signaling and may explain the mild phenotype in Crouzon syndrome with Acanthosis Nigricans. The results presented here provide new knowledge about the physical basis behind growth disorders and highlight the fact that a single RTK mutation may affect multiple steps in RTK activation.
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Affiliation(s)
- Fenghao Chen
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Sarvenaz Sarabipour
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
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Placone J, Hristova K. Direct assessment of the effect of the Gly380Arg achondroplasia mutation on FGFR3 dimerization using quantitative imaging FRET. PLoS One 2012; 7:e46678. [PMID: 23056398 PMCID: PMC3467271 DOI: 10.1371/journal.pone.0046678] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/04/2012] [Indexed: 11/19/2022] Open
Abstract
The Gly380Arg mutation in FGFR3 is the genetic cause for achondroplasia (ACH), the most common form of human dwarfism. The mutation has been proposed to increase FGFR3 dimerization, but the dimerization propensities of wild-type and mutant FGFR3 have not been compared. Here we use quantitative imaging FRET to characterize the dimerization of wild-type FGFR3 and the ACH mutant in plasma membrane-derived vesicles from HEK293T cells. We demonstrate a small, but statistically significant increase in FGFR3 dimerization due to the ACH mutation. The data are consistent with the idea that the ACH mutation causes a structural change which affects both the stability and the activity of FGFR3 dimers in the absence of ligand.
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Affiliation(s)
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
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He L, Serrano C, Niphadkar N, Shobnam N, Hristova K. Effect of the G375C and G346E achondroplasia mutations on FGFR3 activation. PLoS One 2012; 7:e34808. [PMID: 22529939 PMCID: PMC3329527 DOI: 10.1371/journal.pone.0034808] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/08/2012] [Indexed: 11/19/2022] Open
Abstract
Two mutations in FGFR3, G380R and G375C are known to cause achondroplasia, the most common form of human dwarfism. The G380R mutation accounts for 98% of the achondroplasia cases, and thus has been studied extensively. Here we study the effect of the G375C mutation on the phosphorylation and the cross-linking propensity of full-length FGFR3 in HEK 293 cells, and we compare the results to previously published results for the G380R mutant. We observe identical behavior of the two achondroplasia mutants in these experiments, a finding which supports a direct link between the severity of dwarfism phenotypes and the level and mechanism of FGFR3 over-activation. The mutations do not increase the cross-linking propensity of FGFR3, contrary to previous expectations that the achondroplasia mutations stabilize the FGFR3 dimers. Instead, the phosphorylation efficiency within un-liganded FGFR3 dimers is increased, and this increase is likely the underlying cause for pathogenesis in achondroplasia. We further investigate the G346E mutation, which has been reported to cause achondroplasia in one case. We find that this mutation does not increase FGFR3 phosphorylation and decreases FGFR3 cross-linking propensity, a finding which raises questions whether this mutation is indeed a genetic cause for human dwarfism.
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Affiliation(s)
| | | | | | | | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
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29
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Abstract
Fibroblast growth factors (fgfs) play important roles in embryonic development and in adult life by controlling cell proliferation, differentiation, and migration. There are 18 known fgfs which activate four fibroblast growth factor receptors (FGFRs), with different isoforms due to alternative splicing. The physical basis behind the specificity of the biological responses mediated by different fgf-FGFR pairs is currently unknown. To gain insight into the specificity of FGFR3c, a membrane receptor which is critical for bone development, we studied, analyzed, and compared the activation of FGFR3c over a wide range of fgf1 and fgf2 concentrations. We found that while the strength of fgf2 binding to FGFR3c is lower than the strength of fgf1 binding, the fgf2-bound dimers exhibit higher phosphorylation of the critical tyrosines in the activation loop. As a result, fgf1 and fgf2 elicit a similar FGFR3c response at low, but not at high, concentrations. The results demonstrate the versatility of FGFR3c response to fgf1 and fgf2 and highlight the complexity in fgf signaling.
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Affiliation(s)
- Fenghao Chen
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Li E, Wimley WC, Hristova K. Transmembrane helix dimerization: beyond the search for sequence motifs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:183-93. [PMID: 21910966 DOI: 10.1016/j.bbamem.2011.08.031] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/25/2011] [Accepted: 08/26/2011] [Indexed: 01/07/2023]
Abstract
Studies of the dimerization of transmembrane (TM) helices have been ongoing for many years now, and have provided clues to the fundamental principles behind membrane protein (MP) folding. Our understanding of TM helix dimerization has been dominated by the idea that sequence motifs, simple recognizable amino acid sequences that drive lateral interaction, can be used to explain and predict the lateral interactions between TM helices in membrane proteins. But as more and more unique interacting helices are characterized, it is becoming clear that the sequence motif paradigm is incomplete. Experimental evidence suggests that the search for sequence motifs, as mediators of TM helix dimerization, cannot solve the membrane protein folding problem alone. Here we review the current understanding in the field, as it has evolved from the paradigm of sequence motifs into a view in which the interactions between TM helices are much more complex. This article is part of a Special Issue entitled: Membrane protein structure and function.
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Affiliation(s)
- Edwin Li
- Department of Biology, Saint Joseph's University, Philadelphia, PA 19131, USA
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He L, Hristova K. Physical-chemical principles underlying RTK activation, and their implications for human disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:995-1005. [PMID: 21840295 DOI: 10.1016/j.bbamem.2011.07.044] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 12/15/2022]
Abstract
RTKs, the second largest family of membrane receptors, exert control over cell proliferation, differentiation and migration. In recent years, our understanding of RTK structure and activation in health and disease has skyrocketed. Here we describe experimental approaches used to interrogate RTKs, and we review the quantitative biophysical frameworks and structural considerations that shape our understanding of RTK function. We discuss current knowledge about RTK interactions, focusing on the role of different domains in RTK homodimerization, and on the importance and challenges in RTK heterodimerization studies. We also review our understanding of pathogenic RTK mutations, and the underlying physical-chemical causes for the pathologies. This article is part of a Special Issue entitled: Protein Folding in Membranes.
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Affiliation(s)
- Lijuan He
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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High-throughput selection of transmembrane sequences that enhance receptor tyrosine kinase activation. J Mol Biol 2011; 412:43-54. [PMID: 21767549 DOI: 10.1016/j.jmb.2011.07.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/01/2011] [Accepted: 07/05/2011] [Indexed: 12/21/2022]
Abstract
Dimerization is a critical requirement for the activation of the intracellular kinase domains of receptor tyrosine kinases (RTKs). The single transmembrane (TM) helices of RTKs contribute to dimerization, but the details are not well understood. Work with TM helices in various model systems has revealed a small number of specific dimerization sequence motifs, and it has been suggested that RTK dimerization is modulated by such motifs. Yet questions remain about the universality of these sequence motifs for RTK dimerization and about how TM domain dimerization in model systems relates to RTK activation in mammalian membranes. To investigate these questions, we designed a 3888-member combinatorial peptide library based on the TM domain of Neu (ErbB2) as a model RTK. The library contains many closely related, Neu-like sequences, including thousands of sequences with known dimerization motifs. We used an SDS-PAGE-based screen to select peptides that dimerize better than the native Neu sequence, and we assayed the activation of chimeric Neu receptors in mammalian cells with TM sequences selected in the screen. Despite the very high abundance of known dimerization motifs in the library, only a very few dimerizing sequences were identified by SDS-PAGE. About half of those sequences activated the Neu kinase significantly more than did the wild-type TM sequence. This work furthers our knowledge about the requirements for membrane protein interactions and the requirements for RTK activation in cells.
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The A391E mutation enhances FGFR3 activation in the absence of ligand. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2045-50. [PMID: 21536014 DOI: 10.1016/j.bbamem.2011.04.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 04/11/2011] [Accepted: 04/12/2011] [Indexed: 12/20/2022]
Abstract
The A391E mutation in the transmembrane domain of fibroblast growth factor receptor 3 leads to aberrant development of the cranium. It has been hypothesized that the mutant glutamic acid stabilizes the dimeric receptor due to hydrogen bonding and enhances its ligand-independent activation. We previously tested this hypothesis in lipid bilayers and showed that the mutation stabilizes the isolated transmembrane domain dimer by -1.3°kcal/mol. Here we further test the hypothesis, by investigating the effect of the A391E mutation on the activation of full-length fibroblast growth factor receptor 3 in human embryonic kidney 293T cells in the absence of ligand. We find that the mutation enhances the ligand-independent activation propensity of the receptor by -1.7°kcal/mol. This value is consistent with the observed strength of hydrogen bonds in membranes, and supports the above hypothesis.
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He L, Shobnam N, Wimley WC, Hristova K. FGFR3 heterodimerization in achondroplasia, the most common form of human dwarfism. J Biol Chem 2011; 286:13272-81. [PMID: 21324899 DOI: 10.1074/jbc.m110.205583] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The G380R mutation in the transmembrane domain of fibroblast growth factor receptor 3 (FGFR3) causes achondroplasia, the most common form of human dwarfism. Achondroplasia is a heterozygous disorder, and thus the affected individuals express both wild-type and mutant FGFR3. Yet heterodimerization in achondroplasia has not been characterized thus far. To investigate the formation of FGFR3 heterodimers in cellular membranes, we designed an FGFR3 construct that lacks the kinase domain, and we monitored the formation of inactive heterodimers between this construct and wild-type and mutant FGFR3. The formation of the inactive heterodimers depleted the pool of full-length receptors capable of forming active homodimers and ultimately reduced their phosphorylation. By analyzing the effect of the truncated FGFR3 on full-length receptor phosphorylation, we demonstrated that FGFR3 WT/G380R heterodimers form with lower probability than wild-type FGFR3 homodimers at low ligand concentration. These results further our knowledge of FGFR3-associated bone disorders.
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Affiliation(s)
- Lijuan He
- Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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