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Damron EP, McDonald J, Das P, Koay EJ, Koong AC, Ludmir EB, Noticewala SS, Smith GL, Taniguchi CM, Messick C, Chang G, Minsky BD, Morris VK, Holliday E. Salvage Abdominoperineal Resection for Locally Recurrent or Persistent Anal Squamous Cell Carcinoma after Definitive Chemoradiation. Int J Radiat Oncol Biol Phys 2023; 117:e292. [PMID: 37785078 DOI: 10.1016/j.ijrobp.2023.06.1288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Initial treatment for patients with squamous cell carcinoma of the anal canal includes definitive chemoradiation. Salvage abdominoperineal resection (APR) is the treatment of choice for recurrent or persistent disease. Older studies suggest approximately 50% successful salvage of recurrent or persistent disease with APR. Risk factors for failure after salvage APR are incompletely characterized. MATERIALS/METHODS Using a single institutional database, patients were identified who underwent salvage APR after definitive intensity-modulated radiotherapy-based chemoradiation between 2003 and 2022. Clinical and pathologic variables analyzed included age at APR, sex, race, HIV status, initial cT stage, initial cN stage, radiation dose, recurrent vs persistent disease, recurrent pT stage, recurrent pN stage, the presence of LVSI, PNI or <2mm surgical margins, and the use of either intraoperative radiation or another treatment modality in addition to APR. The log rank test was used to determine differences in time from APR to events (local recurrence, distant metastasis and death) based on clinical and pathologic variables. The Cox Proportional Hazard Model was used to perform multivariable analysis for all factors with a univariate P-value <0.1. RESULTS Of 628 patients with anal squamous cell carcinoma, 50 (8.0%) were treated with abdominoperineal resection for locally recurrent (n = 29, 58%) or locally persistent (n = 21, 42%) disease. Median [interquartile range] follow up was 40.0 months [15.2-68.0 months] from APR. Median local recurrence-free survival was not reached; 1- and 2-year local recurrence-free survival was 81% (95% CI 72-92%) and 76% (64-89%). On multivariable analysis, pathologic T-stage of the recurrence (3.85 (1.07-13.9); P = .040), the presence of lymphovascular space invasion (9.1 (1.12-73.62); P = .038) and surgical margins <2mm (8.81 (2.11-36.73); P = .003) were all significantly associated with higher rates of local recurrence. Median distant metastasis-free survival was not reached; 1- and 2-year distant metastasis-free survival was 88% (81-98%) and 79% (67-92%). On multivariable analysis, only persistent (versus recurrent) local disease was significantly associated with higher rates of distant metastasis (1.23 (1.05-5.55) P = .043). Median overall survival was not reached; 1- and 2-year overall survival was 90% (81-98%) and 78% (65-90%). On multivariable analysis, only recurrent pT stage (T3/4 vs T1/2) was associated with higher rates of death (5.87 (1.02-33.65); P = .047). CONCLUSION APR is a successful salvage modality for anal squamous cell carcinoma with recurrent or persistent disease after chemoradiation results. Patients with pT3/4 disease, lymphovascular space invasion, surgical margins <2 mm may be associated with higher re-recurrence rates and may benefit from more frequent monitoring or treatment escalation.
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Affiliation(s)
- E P Damron
- The University of Texas McGovern Medical School, Houston, TX
| | - J McDonald
- USF Health Morsani College of Medicine, Tampa, FL
| | - P Das
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E J Koay
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - A C Koong
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E B Ludmir
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - S S Noticewala
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - G L Smith
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - C M Taniguchi
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - C Messick
- Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - G Chang
- Department of Colon & Rectal Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - B D Minsky
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - V K Morris
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E Holliday
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
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Schrank BR, Gallagher CM, Nguyen L, Morris VK, Holliday E, Newman A, Merriman K, Sudol VM, Chiao EY, Hawk E, Koong AC, Chang S. Sexual Orientation and Gender Identity (SOGI) Data Collection: Opportunities to Advance Best Clinical Practices for LGBTQ+ Patients in Radiation Oncology. Int J Radiat Oncol Biol Phys 2023; 117:e56. [PMID: 37785716 DOI: 10.1016/j.ijrobp.2023.06.770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) A long-standing barrier to progress against health disparities is the lack of data regarding cancer risks, prevalence, treatment, and outcomes for sexual and gender minority (SGM) patients. Sexual orientation and gender identity (SOGI) data are not routinely collected by individual oncologists, cancer centers, or most non-federal hospital systems. Alarmingly high proportions of SGM patients report discrimination in healthcare or avoid routine care due to perceived lack of acceptance in the healthcare system. For these and other reasons, healthcare institutions must adopt practices that promote an inclusive environment for all patients including those self-identified from SGM groups. One strategy to achieve this aim is through SOGI data collection. The purpose of this study was to pilot new procedures and training for SOGI data collection, the aims of this project were to standardize the collection of SOGI data for all new patients referred to the Division of Radiation Oncology; promote clinical staff awareness of SGM health disparities and strategies for fostering an inclusive hospital environment; and to provide SGM patients and caregivers educational resources and support systems tailored to their needs. MATERIALS/METHODS We designed a Quality Improvement program for collecting SOGI data, which was approved by our institution's QIAB. Patient access specialists (PAS) were trained to collect SOGI data from newly registered patients and enter the data into the electronic health record. Radiation Oncology staff completed surveys before and after SOGI training to estimate its impact on the provision of patient care. A Fisher's exact test was utilized to evaluate associations between training and provider-reported outcomes. RESULTS Within a 3-week period starting in January 2023, two 1-hour interactive training sessions were offered to twenty-five PAS. Three 1-hour training sessions were offered to twenty-seven Radiation Oncology clinical staff. (1) Confidence for incorporating SOGI classifiers around patients improved from before training (52%, 13/25) to after training (100%, 17/17) among medical providers surveyed (odds ratio (OR) 32, 95% confidence interval (CI) 0.70-1493, p = 0.005). Use of SOGI data in clinical decision making increased from before training (9/25, 36%) to after training (100%, 17/17) among medical providers (OR 60.79, 95% CI 3.271-1130, p<0.0001). (2) A clinical pathway for SGM patients was developed to facilitate referral to our institution's SGM patient support group and distribution of patient education materials focused on sexual health. CONCLUSION Establishing standardized SOGI data collection can facilitate the provision of tailored resources and care that meets the needs of patients and staff in a large comprehensive cancer center. Specialized training for staff developed through this initiative helps foster an inclusive and welcoming environment that promotes the integration, visibility, and advancement of SGM cancer care at our institution.
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Affiliation(s)
- B R Schrank
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - C M Gallagher
- Department of Critical Care Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - L Nguyen
- Department of Health Disparities Research, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - V K Morris
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E Holliday
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - A Newman
- Department of Patient Safety, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - K Merriman
- Department of Tumor Registry, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - V M Sudol
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E Y Chiao
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E Hawk
- Department of Cancer Prevention & Pop Science, University of Texas MD Anderson Cancer Center, Houston, TX
| | - A C Koong
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - S Chang
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX
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McDonald J, Chang E, Damron EP, Das P, Koay EJ, Koong AC, Ludmir EB, Noticewala SS, Smith GL, Taniguchi CM, Minsky BD, Messick C, Chang G, Morris VK, Holliday E. Outcomes and after Hyperfractionated, Accelerated Reirradiation for Recurrent Anal Squamous Cell Carcinoma. Int J Radiat Oncol Biol Phys 2023; 117:e324. [PMID: 37785153 DOI: 10.1016/j.ijrobp.2023.06.2368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Abdominoperineal resection (APR) is the standard salvage treatment for recurrent or persistent squamous cell carcinoma of the anus (SCCA). However, reirradiation (reRT) can be used preoperatively or for those who are not candidates for surgery. MATERIALS/METHODS Using a single institutional database, patients were identified who underwent reRT for SCCA from 2003 to 2022. Response to reRT and outcomes after reRT were recorded. Variables analyzed included age at reRT, sex, reason for reRT (recurrent SCCA vs new SCCA after pelvic radiation for a different malignancy), interval between initial radiation and reRT, reRT dose, concurrent chemotherapy, receipt of APR and the presence of distant metastases at the time of reRT. Cox Proportional Hazard Model was used; multivariable analysis for all factors with a univariate P-value <0.1 on univariable analysis. RESULTS A total of 42 patients received reRT, which consisted of 1.5 Gray (Gy) twice daily fractions with ≥6-hour interval to a total dose ranging 30Gy to 54Gy (median [IQR] 39Gy [39-42Gy]. Thirty-eight patients (90.5%) received concurrent chemotherapy; most often with weekly cisplatin and 5-fluorouracil (N = 23, 54.8%). Median [IQR] follow-up after reRT was 11.4 months [4.9-40.8 months]. Median [IQR] initial radiation dose was 54Gy [54-58Gy], and median [IQR] interval between initial radiation and reRT was 3.6 years [2.1-6.0 years]. For 8 patients (19.1%), the initial radiation was given for a different pelvic malignancy prior to being diagnosed with SCCA. Four of these patients received brachytherapy alone or in conjunction with external beam. For the remaining 34 patients, the initial radiation was for SCCA and the reRT was for recurrent SCCA either in the anal canal (N = 23, 67.6%) or regional nodes (N = 11, 32.3%). Four patients (9.5%) had distant disease at the time of reRT. Eleven patients (26.2%) had planned APR after preoperative reRT; 1 patient had a pathologic complete response (pCR), 2 patients had a near pCR (<5% viable cancer). Twenty-nine patients (69.0%) were treated with reRT alone; 15 (51.7%) attained a clinical CR. Two patients (4.8%) were treated with palliative intent and response was not assessed. Median local recurrence free survival (LRFS) was 9.9 months; 2- and 3-year LRFS were both 41%. Median distant metastasis free survival (DMFS) was 11.8 months; 2- and 3-year DMFS were 38% and 34%, respectively. Median overall survival (OS) was 40.5 months; 2- and 3-year OS were 54% and 51%, respectively. On multivariable analysis, only the presence of distant disease at the time of reRT was significantly associated with worse LRFS (HR (95% CI) 4.14 (1.34-12.81); P = .014), worse DMFS (4.06 (1.37-12.06); P = .012) and worse OS (5.73 (1.57-20.9); P = .008). CONCLUSION ReRT is an option for patients presenting with either recurrent SCCA or new SCCA after prior pelvic radiation for a different malignancy. ReRT can be given prior to planned salvage APR or alone for patients who are not surgical candidates with an approximate 50% cCR rate.
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Affiliation(s)
- J McDonald
- USF Health Morsani College of Medicine, Tampa, FL
| | - E Chang
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E P Damron
- The University of Texas McGovern Medical School, Houston, TX
| | - P Das
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E J Koay
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - A C Koong
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E B Ludmir
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - S S Noticewala
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - G L Smith
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - C M Taniguchi
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - B D Minsky
- The University of Texas MD Anderson Cancer Center, Houston, TX
| | - C Messick
- Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - G Chang
- Department of Colon & Rectal Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - V K Morris
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - E Holliday
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
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Bozonet SM, Magon NJ, Schwartfeger AJ, Konigstorfer A, Heath SG, Vissers MCM, Morris VK, Göbl C, Murphy JM, Salvesen GS, Hampton MB. Oxidation of caspase-8 by hypothiocyanous acid enables TNF-mediated necroptosis. J Biol Chem 2023:104792. [PMID: 37150321 DOI: 10.1016/j.jbc.2023.104792] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/18/2023] [Accepted: 04/19/2023] [Indexed: 05/09/2023] Open
Abstract
Necroptosis is a form of regulated cell death triggered by various host and pathogen-derived molecules during infection and inflammation. The essential step leading to necroptosis is phosphorylation of the mixed lineage kinase domain-like protein (MLKL) by receptor-interacting protein kinase 3 (RIPK3). Caspase 8 cleaves RIPKs to block necroptosis, so synthetic caspase inhibitors are required to study this process in experimental models. However, it is unclear how caspase-8 activity is regulated in a physiological setting. The active site cysteine of caspases is sensitive to oxidative inactivation, so we hypothesized that oxidants generated at sites of inflammation can inhibit caspase-8 and promote necroptosis. Here, we discovered that hypothiocyanous acid (HOSCN), an oxidant generated in vivo by heme peroxidases including myeloperoxidase and lactoperoxidase, is a potent caspase-8 inhibitor. We found HOSCN was able to promote necroptosis in mouse fibroblasts treated with tumor necrosis factor (TNF). We also demonstrate purified caspase-8 was inactivated by low concentrations of HOSCN, with the predominant product being a disulfide-linked dimer between Cys360 and Cys409 of the large and small catalytic subunits. We show oxidation still occurred in the presence of reducing agents, and reduction of the dimer was slow, consistent with HOSCN being a powerful physiological caspase inhibitor. While the initial oxidation product is a dimer, further modification also occurred in cells treated with HOSCN, leading to higher molecular weight caspase-8 species. Taken together, these findings indicate major disruption of caspase-8 function, and suggest a novel mechanism for the promotion of necroptosis at sites of inflammation.
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Affiliation(s)
- S M Bozonet
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - N J Magon
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - A J Schwartfeger
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - A Konigstorfer
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - S G Heath
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - M C M Vissers
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - V K Morris
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - C Göbl
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand; School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - J M Murphy
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - G S Salvesen
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - M B Hampton
- Mātai Hāora - Centre for Redox Biology and Medicine, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand.
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Harper AR, Dobson RCJ, Morris VK, Moggré GJ. Fermentation of plant-based dairy alternatives by lactic acid bacteria. Microb Biotechnol 2022; 15:1404-1421. [PMID: 35393728 PMCID: PMC9049613 DOI: 10.1111/1751-7915.14008] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 12/19/2022] Open
Abstract
Ethical, environmental and health concerns around dairy products are driving a fast‐growing industry for plant‐based dairy alternatives, but undesirable flavours and textures in available products are limiting their uptake into the mainstream. The molecular processes initiated during fermentation by lactic acid bacteria in dairy products is well understood, such as proteolysis of caseins into peptides and amino acids, and the utilisation of carbohydrates to form lactic acid and exopolysaccharides. These processes are fundamental to developing the flavour and texture of fermented dairy products like cheese and yoghurt, yet how these processes work in plant‐based alternatives is poorly understood. With this knowledge, bespoke fermentative processes could be engineered for specific food qualities in plant‐based foods. This review will provide an overview of recent research that reveals how fermentation occurs in plant‐based milk, with a focus on how differences in plant proteins and carbohydrate structure affect how they undergo the fermentation process. The practical aspects of how this knowledge has been used to develop plant‐based cheeses and yoghurts is also discussed.
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Affiliation(s)
- Aimee R Harper
- Biomolecular Interaction Centre, Food Transitions 2050 Joint Postgraduate School, and School of Biological Sciences, University of Canterbury, PO Box 4800, Christchurch, 8140, New Zealand.,The New Zealand Institute for Plant and Food Research Limited, 74 Gerald St, Lincoln, 7608, New Zealand.,The Riddet Institute, MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Canterbury, PO Box 4800, Christchurch, 8140, New Zealand
| | - Renwick C J Dobson
- Biomolecular Interaction Centre, Food Transitions 2050 Joint Postgraduate School, and School of Biological Sciences, University of Canterbury, PO Box 4800, Christchurch, 8140, New Zealand.,The Riddet Institute, MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Canterbury, PO Box 4800, Christchurch, 8140, New Zealand.,Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Vic., 3010, Australia
| | - Vanessa K Morris
- Biomolecular Interaction Centre, Food Transitions 2050 Joint Postgraduate School, and School of Biological Sciences, University of Canterbury, PO Box 4800, Christchurch, 8140, New Zealand
| | - Gert-Jan Moggré
- The New Zealand Institute for Plant and Food Research Limited, 74 Gerald St, Lincoln, 7608, New Zealand
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Smyth LCD, Murray HC, Hill M, van Leeuwen E, Highet B, Magon NJ, Osanlouy M, Mathiesen SN, Mockett B, Singh-Bains MK, Morris VK, Clarkson AN, Curtis MA, Abraham WC, Hughes SM, Faull RLM, Kettle AJ, Dragunow M, Hampton MB. Neutrophil-vascular interactions drive myeloperoxidase accumulation in the brain in Alzheimer's disease. Acta Neuropathol Commun 2022; 10:38. [PMID: 35331340 PMCID: PMC8944147 DOI: 10.1186/s40478-022-01347-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/11/2022] [Indexed: 01/13/2023] Open
Abstract
INTRODUCTION Neutrophil accumulation is a well-established feature of Alzheimer's disease (AD) and has been linked to cognitive impairment by modulating disease-relevant neuroinflammatory and vascular pathways. Neutrophils express high levels of the oxidant-generating enzyme myeloperoxidase (MPO), however there has been controversy regarding the cellular source and localisation of MPO in the AD brain. MATERIALS AND METHODS We used immunostaining and immunoassays to quantify the accumulation of neutrophils in human AD tissue microarrays and in the brains of APP/PS1 mice. We also used multiplexed immunolabelling to define the presence of NETs in AD. RESULTS There was an increase in neutrophils in AD brains as well as in the murine APP/PS1 model of AD. Indeed, MPO expression was almost exclusively confined to S100A8-positive neutrophils in both human AD and murine APP/PS1 brains. The vascular localisation of neutrophils in both human AD and mouse models of AD was striking and driven by enhanced neutrophil adhesion to small vessels. We also observed rare infiltrating neutrophils and deposits of MPO around plaques. Citrullinated histone H3, a marker of neutrophil extracellular traps (NETs), was also detected in human AD cases at these sites, indicating the presence of extracellular MPO in the vasculature. Finally, there was a reduction in the endothelial glycocalyx in AD that may be responsible for non-productive neutrophil adhesion to the vasculature. CONCLUSION Our report indicates that vascular changes may drive neutrophil adhesion and NETosis, and that neutrophil-derived MPO may lead to vascular oxidative stress and be a relevant therapeutic target in AD.
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Affiliation(s)
- Leon C. D. Smyth
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
- Department of Pathology and Immunology, Center for Brain Immunology and Glia, Washington University in St. Louis, Campus, Box 8118, St. Louis, MO USA
| | - Helen C. Murray
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomy With Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Madison Hill
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
| | - Eve van Leeuwen
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
| | - Blake Highet
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomy With Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Nicholas J. Magon
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
| | - Mahyar Osanlouy
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Sophie N. Mathiesen
- Department of Psychology, University of Otago, Dunedin, New Zealand
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Bruce Mockett
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Malvindar K. Singh-Bains
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomy With Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Vanessa K. Morris
- School of Biological Science, University of Canterbury, Canterbury, New Zealand
| | | | - Maurice A. Curtis
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomy With Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | - Richard L. M. Faull
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomy With Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Anthony J. Kettle
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
| | - Mike Dragunow
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mark B. Hampton
- Centre for Free Radical Research, University of Otago, Christchurch, New Zealand
- Department of Pathology and Biomedical Science, University of Otago, PO Box 4345, Christchurch, 8140 New Zealand
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Göbl C, Morris VK, van Dam L, Visscher M, Polderman PE, Hartlmüller C, de Ruiter H, Hora M, Liesinger L, Birner-Gruenberger R, Vos HR, Reif B, Madl T, Dansen TB. Cysteine oxidation triggers amyloid fibril formation of the tumor suppressor p16 INK4A. Redox Biol 2020; 28:101316. [PMID: 31539802 PMCID: PMC6812003 DOI: 10.1016/j.redox.2019.101316] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/28/2019] [Accepted: 09/01/2019] [Indexed: 02/09/2023] Open
Abstract
The tumor suppressor p16INK4A induces cell cycle arrest and senescence in response to oncogenic transformation and is therefore frequently lost in cancer. p16INK4A is also known to accumulate under conditions of oxidative stress. Thus, we hypothesized it could potentially be regulated by reversible oxidation of cysteines (redox signaling). Here we report that oxidation of the single cysteine in p16INK4A in human cells occurs under relatively mild oxidizing conditions and leads to disulfide-dependent dimerization. p16INK4A is an all α-helical protein, but we find that upon cysteine-dependent dimerization, p16INK4A undergoes a dramatic structural rearrangement and forms aggregates that have the typical features of amyloid fibrils, including binding of diagnostic dyes, presence of cross-β sheet structure, and typical dimensions found in electron microscopy. p16INK4A amyloid formation abolishes its function as a Cyclin Dependent Kinase 4/6 inhibitor. Collectively, these observations mechanistically link the cellular redox state to the inactivation of p16INK4A through the formation of amyloid fibrils.
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Affiliation(s)
- Christoph Göbl
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Vanessa K Morris
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Loes van Dam
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands
| | - Marieke Visscher
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands
| | - Paulien E Polderman
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands
| | - Christoph Hartlmüller
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Hesther de Ruiter
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands
| | - Manuel Hora
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Laura Liesinger
- Omics Center Graz, BioTechMed-Graz, Graz, Austria; Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010, Graz, Austria
| | - Ruth Birner-Gruenberger
- Omics Center Graz, BioTechMed-Graz, Graz, Austria; Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010, Graz, Austria
| | - Harmjan R Vos
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands
| | - Bernd Reif
- Center for Integrated Protein Science Munich (CIPSM) at the Department of Chemistry Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, 85764, Neuherberg, Germany
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010, Graz, Austria; BioTechMed-Graz, Austria.
| | - Tobias B Dansen
- Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands.
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Abstract
The fungal hydrophobins are small proteins that are able to self-assemble spontaneously into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These protein monolayers can reverse the wettability of a surface, making them suitable for increasing the biocompatibility of many hydrophobic nanomaterials. One subgroup of this family, the class I hydrophobins, forms monolayers that are composed of extremely robust amyloid-like fibrils, called rodlets. Here, we describe the protocols for the production and purification of recombinant hydrophobins and oxidative refolding to a biologically active, soluble, monomeric form. We describe methods to trigger the self-assembly into the fibrillar rodlet state and techniques to characterize the physicochemical properties of the polymeric forms.
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Affiliation(s)
- Sarah R Ball
- Discipline of Pharmacology and Sydney Nano, University of Sydney, Sydney, NSW, Australia
| | - Chi L L Pham
- Discipline of Pharmacology and Sydney Nano, University of Sydney, Sydney, NSW, Australia
| | - Victor Lo
- Discipline of Pharmacology and Sydney Nano, University of Sydney, Sydney, NSW, Australia
| | - Vanessa K Morris
- School of Biological Science, University of Canterbury, Canterbury, New Zealand
| | - Ann H Kwan
- School of Life and Environmental Sciences and Sydney Nano, The University of Sydney, Sydney, NSW, Australia
| | - Margaret Sunde
- Discipline of Pharmacology and Sydney Nano, University of Sydney, Sydney, NSW, Australia.
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9
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Parseghian CM, Loree JM, Morris VK, Liu X, Clifton KK, Napolitano S, Henry JT, Pereira AA, Vilar E, Johnson B, Kee B, Raghav K, Dasari A, Wu J, Garg N, Raymond VM, Banks KC, Talasaz AA, Lanman RB, Strickler JH, Hong DS, Corcoran RB, Overman MJ, Kopetz S. Anti-EGFR-resistant clones decay exponentially after progression: implications for anti-EGFR re-challenge. Ann Oncol 2019; 30:243-249. [PMID: 30462160 PMCID: PMC6657008 DOI: 10.1093/annonc/mdy509] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Colorectal cancer (CRC) has been shown to acquire RAS and EGFR ectodomain mutations as mechanisms of resistance to epidermal growth factor receptor (EGFR) inhibition (anti-EGFR). After anti-EGFR withdrawal, RAS and EGFR mutant clones lack a growth advantage relative to other clones and decay; however, the kinetics of decay remain unclear. We sought to determine the kinetics of acquired RAS/EGFR mutations after discontinuation of anti-EGFR therapy. PATIENTS AND METHODS We present the post-progression circulating tumor DNA (ctDNA) profiles of 135 patients with RAS/BRAF wild-type metastatic CRC treated with anti-EGFR who acquired RAS and/or EGFR mutations during therapy. Our validation cohort consisted of an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling. A separate retrospective cohort of 80 patients was used to evaluate overall response rate and progression free survival during re-challenge therapies. RESULTS Our analysis showed that RAS and EGFR relative mutant allele frequency decays exponentially (r2=0.93 for RAS; r2=0.94 for EGFR) with a cumulative half-life of 4.4 months. We validated our findings using an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling, confirming exponential decay with an estimated half-life of 4.3 months. A separate retrospective cohort of 80 patients showed that patients had a higher overall response rate during re-challenge therapies after increasing time intervals, as predicted by our model. CONCLUSION These results provide scientific support for anti-EGFR re-challenge and guide the optimal timing of re-challenge initiation.
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Affiliation(s)
- C M Parseghian
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA.
| | | | - V K Morris
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - X Liu
- Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - K K Clifton
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - S Napolitano
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - J T Henry
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - A A Pereira
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - E Vilar
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA; Division of Cancer Prevention and Population Sciences, Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - B Johnson
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - B Kee
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - K Raghav
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - A Dasari
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - J Wu
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - N Garg
- Division of Diagnostic Imaging, Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | | | - K C Banks
- Guardant Health Inc, Redwood City, USA
| | | | | | | | - D S Hong
- Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - R B Corcoran
- Massachusetts General Hospital Cancer Center, Boston, USA; Department of Medicine, Harvard Medical School, Boston, USA
| | - M J Overman
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - S Kopetz
- Division of Cancer Medicine, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, USA
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Sun Y, Medina Cruz A, Hadley KC, Galant NJ, Law R, Vernon RM, Morris VK, Robertson J, Chakrabartty A. Physiologically Important Electrolytes as Regulators of TDP-43 Aggregation and Droplet-Phase Behavior. Biochemistry 2018; 58:590-607. [DOI: 10.1021/acs.biochem.8b00842] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yulong Sun
- University Health Network, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Alison Medina Cruz
- Department of Medical Biophysics, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Kevin C. Hadley
- University Health Network, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Natalie J. Galant
- University Health Network, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Ryan Law
- Department of Medical Biophysics, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Robert M. Vernon
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Vanessa K. Morris
- University Health Network, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
- School of Biological Sciences, University of Canterbury, Ilam, Christchurch 8041, New Zealand
| | - Janice Robertson
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON M5T 2S8, Canada
| | - Avijit Chakrabartty
- University Health Network, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
- Department of Medical Biophysics, Princess Margaret Cancer Centre, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
- Department of Biochemistry, University of Toronto, TMDT 4-305, 101 College Street, Toronto, ON M5G 1L7, Canada
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11
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Cristóvão JS, Morris VK, Cardoso I, Leal SS, Martínez J, Botelho HM, Göbl C, David R, Kierdorf K, Alemi M, Madl T, Fritz G, Reif B, Gomes CM. The neuronal S100B protein is a calcium-tuned suppressor of amyloid-β aggregation. Sci Adv 2018; 4:eaaq1702. [PMID: 29963623 PMCID: PMC6025902 DOI: 10.1126/sciadv.aaq1702] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 05/22/2018] [Indexed: 05/23/2023]
Abstract
Amyloid-β (Aβ) aggregation and neuroinflammation are consistent features in Alzheimer's disease (AD) and strong candidates for the initiation of neurodegeneration. S100B is one of the most abundant proinflammatory proteins that is chronically up-regulated in AD and is found associated with senile plaques. This recognized biomarker for brain distress may, thus, play roles in amyloid aggregation which remain to be determined. We report a novel role for the neuronal S100B protein as suppressor of Aβ42 aggregation and toxicity. We determined the structural details of the interaction between monomeric Aβ42 and S100B, which is favored by calcium binding to S100B, possibly involving conformational switching of disordered Aβ42 into an α-helical conformer, which locks aggregation. From nuclear magnetic resonance experiments, we show that this dynamic interaction occurs at a promiscuous peptide-binding region within the interfacial cleft of the S100B homodimer. This physical interaction is coupled to a functional role in the inhibition of Aβ42 aggregation and toxicity and is tuned by calcium binding to S100B. S100B delays the onset of Aβ42 aggregation by interacting with Aβ42 monomers inhibiting primary nucleation, and the calcium-bound state substantially affects secondary nucleation by inhibiting fibril surface-catalyzed reactions through S100B binding to growing Aβ42 oligomers and fibrils. S100B protects cells from Aβ42-mediated toxicity, rescuing cell viability and decreasing apoptosis induced by Aβ42 in cell cultures. Together, our findings suggest that molecular targeting of S100B could be translated into development of novel approaches to ameliorate AD neurodegeneration.
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Affiliation(s)
- Joana S. Cristóvão
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Vanessa K. Morris
- Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Isabel Cardoso
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sónia S. Leal
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Javier Martínez
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Hugo M. Botelho
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Christoph Göbl
- Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Rodrigo David
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Katrin Kierdorf
- Department of Neuropathology, University of Freiburg, Freiburg, Germany
| | - Mobina Alemi
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Faculdade de Medicina, Universidade do Porto, Porto, Portugal
| | - Tobias Madl
- Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Günter Fritz
- Department of Neuropathology, University of Freiburg, Freiburg, Germany
| | - Bernd Reif
- Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Cláudio M. Gomes
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
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Morris VK, Carrique-Mas JJ, Mueller-Doblies D, Davies RH, Wales AD, Allen VM. A longitudinal observational study of Salmonella shedding patterns by commercial turkeys during rearing and fattening, showing limitations of some control measures. Br Poult Sci 2015; 56:48-57. [PMID: 25654335 DOI: 10.1080/00071668.2014.991273] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
1. The onset and progression of Salmonella infections was investigated in commercial turkey flocks from placement at 1 d old until slaughter in "brood and move" systems using a longitudinal observational approach based on faeces and environmental sampling with subsequent culture of Salmonella. 2. Persistent Salmonella Newport contamination was found within rearing houses and on their external concrete aprons after cleaning and disinfection between crops of heavily shedding young birds. 3. Salmonella shedding was often detected by 5 d of age and the frequency of positive samples peaked at 14-35 d. Thereafter Salmonella isolations declined, especially in the later (fattening) stages. Samples were still Salmonella-positive at low prevalence in half of the intensively sampled houses at slaughter age. 4. A number of management interventions to combat Salmonella infection of flocks, including sourcing policy, competitive exclusion cultures and cleaning and disinfection, were inadequate to prevent flock infection, although improved disinfection on one unit was associated with a delay in the onset of flock infection.
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Affiliation(s)
- V K Morris
- a Department of Clinical Veterinary Science , University of Bristol , Bristol , UK
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13
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Morelli MP, Overman MJ, Dasari A, Kazmi SMA, Mazard T, Vilar E, Morris VK, Lee MS, Herron D, Eng C, Morris J, Kee BK, Janku F, Deaton FL, Garrett C, Maru D, Diehl F, Angenendt P, Kopetz S. Characterizing the patterns of clonal selection in circulating tumor DNA from patients with colorectal cancer refractory to anti-EGFR treatment. Ann Oncol 2015; 26:731-736. [PMID: 25628445 PMCID: PMC4374387 DOI: 10.1093/annonc/mdv005] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION KRAS and EGFR ectodomain-acquired mutations in patients with metastatic colorectal cancer (mCRC) have been correlated with acquired resistance to anti-EGFR monoclonal antibodies (mAbs). We investigated the frequency, co-occurrence, and distribution of acquired KRAS and EGFR mutations in patients with mCRC refractory to anti-EGFR mAbs using circulating tumor DNA (ctDNA). PATIENTS AND METHODS Sixty-two post-treatment plasma and 20 matching pretreatment archival tissue samples from KRAS (wt) mCRC patients refractory to anti-EGFR mAbs were evaluated by high-sensitivity emulsion polymerase chain reaction for KRAS codon 12, 13, 61, and 146 and EGFR 492 mutations. RESULTS Plasma analyses showed newly detectable EGFR and KRAS mutations in 5/62 [8%; 95% confidence interval (CI) 0.02-0.18] and 27/62 (44%; 95% CI 0.3-0.56) samples, respectively. KRAS codon 61 and 146 mutations were predominant (33% and 11%, respectively), and multiple EGFR and/or KRAS mutations were detected in 11/27 (41%) cases. The percentage of mutant allele reads was inversely correlated with time since last treatment with EGFR mAbs (P = 0.038). In the matching archival tissue, these mutations were detectable as low-allele-frequency clones in 35% of patients with plasma mutations after treatment with anti-EGFR mAbs and correlated with shorter progression-free survival (PFS) compared with the cases with no new mutations (3.0 versus 8.0 months, P = 0.0004). CONCLUSION Newly detected KRAS and/or EGFR mutations in plasma ctDNA from patients refractory to anti-EGFR treatment appear to derive from rare, pre-existing clones in the primary tumors. These rare clones were associated with shorter PFS in patients receiving anti-EGFR treatment. Multiple simultaneous mutations in KRAS and EGFR in the ctDNA and the decline in allele frequency after discontinuation of anti-EGFR therapy in a subset of patients suggest that several resistance mechanisms can co-exist and that relative clonal burdens may change over time. Monitoring treatment-induced genetic alterations by sequencing ctDNA could identify biomarkers for treatment screening in anti-EGFR-refractory patients.
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Affiliation(s)
- M P Morelli
- Department of Gastrointestinal Medical Oncology
| | - M J Overman
- Department of Gastrointestinal Medical Oncology
| | - A Dasari
- Department of Gastrointestinal Medical Oncology
| | - S M A Kazmi
- Department of Gastrointestinal Medical Oncology
| | - T Mazard
- Department of Gastrointestinal Medical Oncology
| | - E Vilar
- Department of Gastrointestinal Medical Oncology; Clinical Cancer Prevention
| | - V K Morris
- Department of Gastrointestinal Medical Oncology
| | - M S Lee
- Department of Gastrointestinal Medical Oncology
| | - D Herron
- Department of Gastrointestinal Medical Oncology
| | - C Eng
- Department of Gastrointestinal Medical Oncology
| | - J Morris
- Investigational Cancer Therapeutics
| | - B K Kee
- Department of Gastrointestinal Medical Oncology
| | | | - F L Deaton
- Department of Gastrointestinal Medical Oncology
| | - C Garrett
- Department of Gastrointestinal Medical Oncology
| | - D Maru
- Pathology, The University of Texas MD Anderson Cancer Center, Houston, USA
| | - F Diehl
- Sysmex Inostics, Hamburg, Germany
| | | | - S Kopetz
- Department of Gastrointestinal Medical Oncology.
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14
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Morris VK, Lucas FAS, Overman MJ, Eng C, Morelli MP, Jiang ZQ, Luthra R, Meric-Bernstam F, Maru D, Scheet P, Kopetz S, Vilar E. Clinicopathologic characteristics and gene expression analyses of non-KRAS 12/13, RAS-mutated metastatic colorectal cancer. Ann Oncol 2014; 25:2008-2014. [PMID: 25009008 PMCID: PMC4176451 DOI: 10.1093/annonc/mdu252] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 06/18/2014] [Accepted: 06/20/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND KRAS mutations in codons 12 and 13 are present in ∼40% of all colorectal cancers (CRC). Activating mutations in codons 61 and 146 of KRAS and in codons 12, 13, and 61 of NRAS also occur but are less frequent. The clinicopathologic features and gene expression profiles of this latter subpopulation of RAS-mutant colorectal tumors have not yet been clearly defined but in general are treated similarly to those with KRAS 12 or 13 mutations. PATIENTS AND METHODS Records of patients with metastatic CRC (mCRC) treated at MD Anderson Cancer Center between December 2000 and August 2012 were reviewed for RAS (KRAS or NRAS) and BRAF mutation status, clinical characteristics, and survival outcomes. To study further with an independent cohort, data from The Cancer Genome Atlas were analyzed to define a gene expression signature for patients whose tumors feature these atypical RAS mutations and explore differences with KRAS 12/13-mutated colorectal tumors. RESULTS Among the 484 patients reviewed, KRAS 12/13, KRAS 61/146, NRAS, and BRAF mutations were detected in 47.7%, 3.0%, 4.1%, and 7.4%, respectively, of patients who were tested for each of these aberrations. Lung metastases were more common in both the KRAS 12/13-mutated and atypical RAS-mutated cohorts relative to patients with RAS/BRAF wild-type tumors. Gene expression analyses revealed similar patterns regardless of the site of RAS mutation, and in silico functional algorithms predicted that KRAS and NRAS mutations in codons 12, 13, 61, and 146 alter the protein function and drive tumorgenesis. CONCLUSIONS Clinicopathologic characteristics, survival outcomes, functional impact, and gene expression profiling were similar between patients with KRAS 12/13 and those with NRAS or KRAS 61/146-mutated mCRC. These clinical and bioinformatic findings support the notion that colorectal tumors driven by these RAS mutations are phenotypically similar.
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Affiliation(s)
- V K Morris
- Department of Cancer Medicine, The University of Texas-MD Anderson Cancer Center, Houston
| | - F A San Lucas
- Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston, USA
| | - M J Overman
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston
| | - C Eng
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston
| | - M P Morelli
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston
| | - Z-Q Jiang
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston
| | - R Luthra
- Department of Hematopathology, The University of Texas-MD Anderson Cancer Center, Houston
| | - F Meric-Bernstam
- Department of Surgical Oncology, The University of Texas-MD Anderson Cancer Center, Houston
| | - D Maru
- Department of Pathology, The University of Texas-MD Anderson Cancer Center, Houston
| | - P Scheet
- Department of Epidemiology, The University of Texas-MD Anderson Cancer Center, Houston
| | - S Kopetz
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston; Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston, USA
| | - E Vilar
- Department of Gastrointestinal Medical Oncology, The University of Texas-MD Anderson Cancer Center, Houston; Clinical Cancer Prevention, The University of Texas-MD Anderson Cancer Center, Houston.
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15
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Lo VC, Ren Q, Pham CLL, Morris VK, Kwan AH, Sunde M. Fungal Hydrophobin Proteins Produce Self-Assembling Protein Films with Diverse Structure and Chemical Stability. Nanomaterials (Basel) 2014; 4:827-843. [PMID: 28344251 PMCID: PMC5304692 DOI: 10.3390/nano4030827] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/22/2014] [Accepted: 09/05/2014] [Indexed: 11/23/2022]
Abstract
Hydrophobins are small proteins secreted by fungi and which spontaneously assemble into amphipathic layers at hydrophilic-hydrophobic interfaces. We have examined the self-assembly of the Class I hydrophobins EAS∆15 and DewA, the Class II hydrophobin NC2 and an engineered chimeric hydrophobin. These Class I hydrophobins form layers composed of laterally associated fibrils with an underlying amyloid structure. These two Class I hydrophobins, despite showing significant conformational differences in solution, self-assemble to form fibrillar layers with very similar structures and require a hydrophilic-hydrophobic interface to trigger self-assembly. Addition of additives that influence surface tension can be used to manipulate the fine structure of the protein films. The Class II hydrophobin NC2 forms a mesh-like protein network and the engineered chimeric hydrophobin displays two multimeric forms, depending on assembly conditions. When formed on a graphite surface, the fibrillar EAS∆15 layers are resistant to alcohol, acid and basic washes. In contrast, the NC2 Class II monolayers are dissociated by alcohol treatment but are relatively stable towards acid and base washes. The engineered chimeric Class I/II hydrophobin shows increased stability towards alcohol and acid and base washes. Self-assembled hydrophobin films may have extensive applications in biotechnology where biocompatible; amphipathic coatings facilitate the functionalization of nanomaterials.
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Affiliation(s)
- Victor C Lo
- Discipline of Pharmacology, School of Medical Sciences, The University of Sydney, Sydney NSW 2006, Australia.
| | - Qin Ren
- Discipline of Pharmacology, School of Medical Sciences, The University of Sydney, Sydney NSW 2006, Australia.
| | - Chi L L Pham
- Discipline of Pharmacology, School of Medical Sciences, The University of Sydney, Sydney NSW 2006, Australia.
| | - Vanessa K Morris
- Discipline of Pharmacology, School of Medical Sciences, The University of Sydney, Sydney NSW 2006, Australia.
- School of Molecular Bioscience, The University of Sydney, Sydney NSW 2006, Australia.
| | - Ann H Kwan
- School of Molecular Bioscience, The University of Sydney, Sydney NSW 2006, Australia.
| | - Margaret Sunde
- Discipline of Pharmacology, School of Medical Sciences, The University of Sydney, Sydney NSW 2006, Australia.
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16
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Linser R, Bardiaux B, Andreas L, Hyberts SG, Morris VK, Pintacuda G, Sunde M, Kwan AH, Wagner G. Solid-state NMR structure determination from diagonal-compensated, sparsely nonuniform-sampled 4D proton-proton restraints. J Am Chem Soc 2014; 136:11002-10. [PMID: 24988008 PMCID: PMC4132958 DOI: 10.1021/ja504603g] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Indexed: 01/21/2023]
Abstract
We report acquisition of diagonal-compensated protein structural restraints from four-dimensional solid-state NMR spectra on extensively deuterated and (1)H back-exchanged proteins. To achieve this, we use homonuclear (1)H-(1)H correlations with diagonal suppression and nonuniform sampling (NUS). Suppression of the diagonal allows the accurate identification of cross-peaks which are otherwise obscured by the strong autocorrelation or whose intensity is biased due to partial overlap with the diagonal. The approach results in unambiguous spectral interpretation and relatively few but reliable restraints for structure calculation. In addition, the diagonal suppression produces a spectrum with low dynamic range for which ultrasparse NUS data sets can be readily reconstructed, allowing straightforward application of NUS with only 2% sampling density with the advantage of more heavily sampling time-domain regions of high signal intensity. The method is demonstrated here for two proteins, α-spectrin SH3 microcrystals and hydrophobin functional amyloids. For the case of SH3, suppression of the diagonal results in facilitated identification of unambiguous restraints and improvement of the quality of the calculated structural ensemble compared to nondiagonal-suppressed 4D spectra. For the only partly assigned hydrophobin rodlets, the structure is yet unknown. Applied to this protein of biological significance with large inhomogeneous broadening, the method allows identification of unambiguous crosspeaks that are otherwise obscured by the diagonal.
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Affiliation(s)
- Rasmus Linser
- Max-Planck
Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- School
of Chemistry, University of New South Wales, Sydney NSW 2052, Australia
| | - Benjamin Bardiaux
- Unité
de Bioinformatique Structurale, CNRS UMR 3528, Institut Pasteur, Paris CEDEX 15, France
| | - Loren
B. Andreas
- Institut
des Sciences Analytiques, UMR 5280 CNRS/Ecole Normale Supérieure
de Lyon/Université de Lyon 1, 69100 Villeurbanne, France
| | - Sven G. Hyberts
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Vanessa K. Morris
- School
of Medical Sciences and School of Molecular Bioscience, University of Sydney, Sydney NSW 2006, Australia
| | - Guido Pintacuda
- Institut
des Sciences Analytiques, UMR 5280 CNRS/Ecole Normale Supérieure
de Lyon/Université de Lyon 1, 69100 Villeurbanne, France
| | - Margaret Sunde
- School
of Medical Sciences and School of Molecular Bioscience, University of Sydney, Sydney NSW 2006, Australia
| | - Ann H. Kwan
- School
of Medical Sciences and School of Molecular Bioscience, University of Sydney, Sydney NSW 2006, Australia
| | - Gerhard Wagner
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
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Morris VK, Kwan AH, Sunde M. Analysis of the structure and conformational states of DewA gives insight into the assembly of the fungal hydrophobins. J Mol Biol 2012; 425:244-56. [PMID: 23137797 DOI: 10.1016/j.jmb.2012.10.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 10/10/2012] [Accepted: 10/30/2012] [Indexed: 11/19/2022]
Abstract
The hydrophobin DewA from the fungus Aspergillus nidulans is a highly surface-active protein that spontaneously self-assembles into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These monolayers are composed of fibrils that are a form of functional amyloid. While there has been significant interest in the use of DewA for a variety of surface coatings and as an emulsifier in biotechnological applications, little is understood about the structure of the protein or the mechanism of self-assembly. We have solved the solution NMR structure of DewA. While the pattern of four disulfide bonds that is a defining feature of hydrophobins is conserved, the arrangement and composition of secondary-structure elements in DewA are quite different to what has been observed in other hydrophobin structures. In addition, we demonstrate that DewA populates two conformations in solution, both of which are assembly competent. One conformer forms a dimer at high concentrations, but this dimer is off-pathway to fibril formation and may represent an assembly control mechanism. These data highlight the structural differences between fibril-forming hydrophobins and those that form amorphous monolayers. This work will open up new opportunities for the engineering of hydrophobins with novel biotechnological applications.
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Affiliation(s)
- Vanessa K Morris
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
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18
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Morris VK, Linser R, Wilde KL, Duff AP, Sunde M, Kwan AH. Festkörper-NMR-Spektroskopie an funktionellen Amyloiden eines Pilz-Hydrophobins: Hinweise auf einen geordneten β-Faltblattkern bei genereller struktureller Heterogenität. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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19
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Morris VK, Linser R, Wilde KL, Duff AP, Sunde M, Kwan AH. Solid-state NMR spectroscopy of functional amyloid from a fungal hydrophobin: a well-ordered β-sheet core amidst structural heterogeneity. Angew Chem Int Ed Engl 2012; 51:12621-5. [PMID: 23125123 DOI: 10.1002/anie.201205625] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Indexed: 11/12/2022]
Abstract
GrEASy fibrils: Hydrophobins are fungal proteins that assemble into an amphipathic fibrillar monolayer with amyloid properties and a hydrophobic face as water-resistant as Teflon. Solid-state NMR studies on EAS hydrophobin fibrils reveal direct evidence of a partial molecular rearrangement on assembly and an ordered β-sheet-rich core in the context of a whole protein in this functional amyloid.
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Affiliation(s)
- Vanessa K Morris
- School of Medical Sciences and School of Molecular Bioscience, University of Sydney, Sydney, Australia
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20
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Yang W, Ren Q, Wu YN, Morris VK, Rey AA, Braet F, Kwan AH, Sunde M. Surface functionalization of carbon nanomaterials by self-assembling hydrophobin proteins. Biopolymers 2012; 99:84-94. [DOI: 10.1002/bip.22146] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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21
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Morris VK, Kwan AH, Mackay JP, Sunde M. Backbone and sidechain ¹H, ¹³C and ¹⁵N chemical shift assignments of the hydrophobin DewA from Aspergillus nidulans. Biomol NMR Assign 2012; 6:83-86. [PMID: 21845363 DOI: 10.1007/s12104-011-9330-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 07/26/2011] [Indexed: 05/31/2023]
Abstract
Hydrophobins are proteins secreted by filamentous fungi that are able to self-assemble into monolayers at hydrophobic:hydrophilic interfaces. The layers are amphipathic and can reverse the wettability of surfaces. Hydrophobins have several roles in fungal development, including the formation of coatings on fungal structures to render them hydrophobic. Here we report the backbone and sidechain assignments for the class I hydrophobin DewA from the fungus Aspergillus nidulans.
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Affiliation(s)
- Vanessa K Morris
- School of Molecular Bioscience, Building G08, University of Sydney, Sydney, NSW 2006, Australia
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Morris VK, Ren Q, Macindoe I, Kwan AH, Byrne N, Sunde M. Recruitment of class I hydrophobins to the air:water interface initiates a multi-step process of functional amyloid formation. J Biol Chem 2011; 286:15955-63. [PMID: 21454575 DOI: 10.1074/jbc.m110.214197] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class I fungal hydrophobins form amphipathic monolayers composed of amyloid rodlets. This is a remarkable case of functional amyloid formation in that a hydrophobic:hydrophilic interface is required to trigger the self-assembly of the proteins. The mechanism of rodlet formation and the role of the interface in this process have not been well understood. Here, we have studied the effect of a range of additives, including ionic liquids, alcohols, and detergents, on rodlet formation by two class I hydrophobins, EAS and DewA. Although the conformation of the hydrophobins in these different solutions is not altered, we observe that the rate of rodlet formation is slowed as the surface tension of the solution is decreased, regardless of the nature of the additive. These results suggest that interface properties are of critical importance for the recruitment, alignment, and structural rearrangement of the amphipathic hydrophobin monomers. This work gives insight into the forces that drive macromolecular assembly of this unique family of proteins and allows us to propose a three-stage model for the interface-driven formation of rodlets.
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Affiliation(s)
- Vanessa K Morris
- School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia
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23
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Kwan AH, Macindoe I, Vukasin PV, Morris VK, Kass I, Gupte R, Mark AE, Templeton MD, Mackay JP, Sunde M. The Cys3-Cys4 loop of the hydrophobin EAS is not required for rodlet formation and surface activity. J Mol Biol 2008; 382:708-20. [PMID: 18674544 DOI: 10.1016/j.jmb.2008.07.034] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 07/08/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022]
Abstract
Class I hydrophobins are fungal proteins that self-assemble into robust amphipathic rodlet monolayers on the surface of aerial structures such as spores and fruiting bodies. These layers share many structural characteristics with amyloid fibrils and belong to the growing family of functional amyloid-like materials produced by microorganisms. Although the three-dimensional structure of the soluble monomeric form of a class I hydrophobin has been determined, little is known about the molecular structure of the rodlets or their assembly mechanism. Several models have been proposed, some of which suggest that the Cys3-Cys4 loop has a critical role in the initiation of assembly or in the polymeric structure. In order to provide insight into the relationship between hydrophobin sequence and rodlet assembly, we investigated the role of the Cys3-Cys4 loop in EAS, a class I hydrophobin from Neurospora crassa. Remarkably, deletion of up to 15 residues from this 25-residue loop does not impair rodlet formation or reduce the surface activity of the protein, and the physicochemical properties of rodlets formed by this mutant are indistinguishable from those of its full-length counterpart. In addition, the core structure of the truncation mutant is essentially unchanged. Molecular dynamics simulations carried out on the full-length protein and this truncation mutant binding to an air-water interface show that, although it is hydrophobic, the loop does not play a role in positioning the protein at the surface. These results demonstrate that the Cys3-Cys4 loop does not have an integral role in the formation or structure of the rodlets and that the major determinant of the unique properties of these proteins is the amphipathic core structure, which is likely to be preserved in all hydrophobins despite the high degree of sequence variation across the family.
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Affiliation(s)
- Ann H Kwan
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, New South Wales 2006, Australia
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