355 results on '"Cullen PJ"'
Search Results
2. The importance of superoxide anion for Escherichia coli biofilm removal using plasma-activated water
- Author
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Xia, B, Vyas, HKN, Zhou, R, Zhang, T, Hong, J, Rothwell, JG, Rice, SA, Carter, D, Ostrikov, K, Cullen, PJ, Mai-Prochnow, A, Xia, B, Vyas, HKN, Zhou, R, Zhang, T, Hong, J, Rothwell, JG, Rice, SA, Carter, D, Ostrikov, K, Cullen, PJ, and Mai-Prochnow, A
- Abstract
Microbial biofilms cause contaminations in different environmental settings, including pipelines, filters, membranes, food and processing infrastructure. They ultimately pose a major risk to human health and necessitate costly cleaning and repair. Cold plasma, a partially ionised gas, and plasma-activated water (PAW) exhibit powerful disinfectant activity. However, the optimal generating conditions, such as the choice of gas used to produce PAW, remain unclear. Here, a range of different PAWs were generated from argon, nitrogen, air, and oxygen in a plasma bubble spark discharge (BSD) reactor capable of directly treating Escherichia coli (ATCC 25922) biofilms in situ. We measured the reactive oxygen and nitrogen species (RONS) (H2O2, NO3-, NO2-) in PAW and the excited species via optical emission spectroscopy (OES). PAW generated using oxygen (PAW-O2) was the most effective and completely removed E. coli biofilms on stainless steel surfaces. Confocal microscopy demonstrated that PAW treatment removed most biofilm cells from the surface with only a few dead cells remaining. We demonstrated that intracellular ROS level increases significantly in the PAW-O2-treated biofilms. Using molecular scavengers, we showed that superoxide anion radical (•O2-) played a critical role in the inactivation of E. coli biofilms. We also confirmed the generation of •O2- in the PAW-O2 via electron paramagnetic resonance (EPR) spectrometry. The potential chemical reactions that occurred in PAW were hypothesized via optical emission spectra (OES). Our results demonstrate the importance of input gas and plasma operating conditions to maximise effective RONS production for optimal biofilm removal under real environmental and industry-relevant conditions.
- Published
- 2023
3. Plasma activated water as a pre-treatment strategy in the context of biofilm-infected chronic wounds.
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Vyas, HKN, Xia, B, Alam, D, Gracie, NP, Rothwell, JG, Rice, SA, Carter, D, Cullen, PJ, Mai-Prochnow, A, Vyas, HKN, Xia, B, Alam, D, Gracie, NP, Rothwell, JG, Rice, SA, Carter, D, Cullen, PJ, and Mai-Prochnow, A
- Abstract
Healing and treatment of chronic wounds are often complicated due to biofilm formation by pathogens. Here, the efficacy of plasma activated water (PAW) as a pre-treatment strategy has been investigated prior to the application of topical antiseptics polyhexamethylene biguanide, povidone iodine, and MediHoney, which are routinely used to treat chronic wounds. The efficacy of this treatment strategy was determined against biofilms of Escherichia coli formed on a plastic substratum and on a human keratinocyte monolayer substratum used as an in vitro biofilm-skin epithelial cell model. PAW pre-treatment greatly increased the killing efficacy of all the three antiseptics to eradicate the E. coli biofilms formed on the plastic and keratinocyte substrates. However, the efficacy of the combined PAW-antiseptic treatment and single treatments using PAW or antiseptic alone was lower for biofilms formed in the in vitro biofilm-skin epithelial cell model compared to the plastic substratum. Scavenging assays demonstrated that reactive species present within the PAW were largely responsible for its anti-biofilm activity. PAW treatment resulted in significant intracellular reactive oxygen and nitrogen species accumulation within the E. coli biofilms, while also rapidly acting on the microbial membrane leading to outer membrane permeabilisation and depolarisation. Together, these factors contribute to significant cell death, potentiating the antibacterial effect of the assessed antiseptics.
- Published
- 2023
4. Proteomic identification and structural basis for the interaction between sorting nexin SNX17 and PDLIM family proteins
- Author
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Healy, MD, Sacharz, J, McNally, KE, McConville, C, Tillu, VA, Hall, RJ, Chilton, M, Cullen, PJ, Mobli, M, Ghai, R, Stroud, DA, Collins, BM, Healy, MD, Sacharz, J, McNally, KE, McConville, C, Tillu, VA, Hall, RJ, Chilton, M, Cullen, PJ, Mobli, M, Ghai, R, Stroud, DA, and Collins, BM
- Abstract
The sorting nexin SNX17 controls endosomal recycling of transmembrane cargo proteins including integrins, the amyloid precursor protein, and lipoprotein receptors. This requires association with the Commander trafficking complex and depends on the C terminus of SNX17 through unknown mechanisms. Using proteomics, we find that the SNX17 C terminus is sufficient for Commander interaction and also associates with members of the PDZ and LIM domain (PDLIM) family. SNX17 contains a type III PDZ binding motif that binds specifically to the PDLIM proteins. The structure of the PDLIM7 PDZ domain bound to the SNX17 C terminus reveals an unconventional perpendicular peptide interaction mediated by electrostatic contacts and a uniquely conserved proline-containing loop sequence in the PDLIM protein family. Our results define the mechanism of SNX17-PDLIM interaction and suggest that the PDLIM proteins may play a role in regulating the activity of SNX17 in conjunction with Commander and actin-rich endosomal trafficking domains.
- Published
- 2022
5. Monitoring fluid-bed granulation and milling processes in-line with real-time imaging
- Author
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Jones, I., Okkonen, Matti-Antero, Greene, A., and Cullen, PJ.
- Subjects
Powders -- Properties ,Drugs -- Vehicles ,Pharmaceutical research ,Drug delivery systems -- Research ,Business ,Pharmaceuticals and cosmetics industries - Abstract
The pharmaceutical manufacturing platforms of fluid-bed granulation and milling are widely used to modify particle size. However, the adoption of process analytical technology to monitor and control these processes is [...]
- Published
- 2015
6. Sorting nexin 5 mediates virus-induced autophagy and immunity
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Dong, X, Yang, Y, Zou, Z, Zhao, Y, Ci, B, Zhong, L, Bhave, M, Wang, L, Kuo, Y-C, Zang, X, Zhong, R, Aguilera, ER, Richardson, RB, Simonetti, B, Schoggins, JW, Pfeiffer, JK, Yu, L, Zhang, X, Xie, Y, Schmid, SL, Xiao, G, Gleeson, PA, Ktistakis, NT, Cullen, PJ, Xavier, RJ, Levine, B, Dong, X, Yang, Y, Zou, Z, Zhao, Y, Ci, B, Zhong, L, Bhave, M, Wang, L, Kuo, Y-C, Zang, X, Zhong, R, Aguilera, ER, Richardson, RB, Simonetti, B, Schoggins, JW, Pfeiffer, JK, Yu, L, Zhang, X, Xie, Y, Schmid, SL, Xiao, G, Gleeson, PA, Ktistakis, NT, Cullen, PJ, Xavier, RJ, and Levine, B
- Abstract
Autophagy, a process of degradation that occurs via the lysosomal pathway, has an essential role in multiple aspects of immunity, including immune system development, regulation of innate and adaptive immune and inflammatory responses, selective degradation of intracellular microorganisms, and host protection against infectious diseases1,2. Autophagy is known to be induced by stimuli such as nutrient deprivation and suppression of mTOR, but little is known about how autophagosomal biogenesis is initiated in mammalian cells in response to viral infection. Here, using genome-wide short interfering RNA screens, we find that the endosomal protein sorting nexin 5 (SNX5)3,4 is essential for virus-induced, but not for basal, stress- or endosome-induced, autophagy. We show that SNX5 deletion increases cellular susceptibility to viral infection in vitro, and that Snx5 knockout in mice enhances lethality after infection with several human viruses. Mechanistically, SNX5 interacts with beclin 1 and ATG14-containing class III phosphatidylinositol-3-kinase (PI3KC3) complex 1 (PI3KC3-C1), increases the lipid kinase activity of purified PI3KC3-C1, and is required for endosomal generation of phosphatidylinositol-3-phosphate (PtdIns(3)P) and recruitment of the PtdIns(3)P-binding protein WIPI2 to virion-containing endosomes. These findings identify a context- and organelle-specific mechanism-SNX5-dependent PI3KC3-C1 activation at endosomes-for initiation of autophagy during viral infection.
- Published
- 2021
7. Interactions of plasma-activated water with biofilms: inactivation, dispersal effects and mechanisms of action.
- Author
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Mai-Prochnow, A, Zhou, R, Zhang, T, Ostrikov, KK, Mugunthan, S, Rice, SA, Cullen, PJ, Mai-Prochnow, A, Zhou, R, Zhang, T, Ostrikov, KK, Mugunthan, S, Rice, SA, and Cullen, PJ
- Abstract
Biofilms have several characteristics that ensure their survival in a range of adverse environmental conditions, including high cell numbers, close cell proximity to allow easy genetic exchange (e.g., for resistance genes), cell communication and protection through the production of an exopolysaccharide matrix. Together, these characteristics make it difficult to kill undesirable biofilms, despite the many studies aimed at improving the removal of biofilms. An elimination method that is safe, easy to deliver in physically complex environments and not prone to microbial resistance is highly desired. Cold atmospheric plasma, a lightning-like state generated from air or other gases with a high voltage can be used to make plasma-activated water (PAW) that contains many active species and radicals that have antimicrobial activity. Recent studies have shown the potential for PAW to be used for biofilm elimination without causing the bacteria to develop significant resistance. However, the precise mode of action is still the subject of debate. This review discusses the formation of PAW generated species and their impacts on biofilms. A focus is placed on the diffusion of reactive species into biofilms, the formation of gradients and the resulting interaction with the biofilm matrix and specific biofilm components. Such an understanding will provide significant benefits for tackling the ubiquitous problem of biofilm contamination in food, water and medical areas.
- Published
- 2021
8. Non thermal processing
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Tiwari, B.K., primary, Cullen, PJ, additional, Brennan, Charles S., additional, and O'Donnell, Colm P., additional
- Published
- 2013
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9. Where Physics Meets (BIO-)Chemistry: Reactive Plasmas for Sustainable Processing and Activation
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Zhou, Renwu, primary, Cullen, PJ, additional, Zhou, Rusen, additional, Bazaka, Kateryna, additional, and Ostrikov, Kostya Ken, additional
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- 2020
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10. Effect of Ozonation on the Physicochemical, Thermal and Structural Properties of Wheat Starch Samples
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Gupta, M, primary, Tiwari, BK, additional, Brennan, C.S., additional, Cullen, PJ, additional, and O'Donnell, Colm, additional
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- 2012
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11. A comparative study on the performance of three treatment chamber designs for radio frequency electric field processing
- Author
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Masood, H, Diao, Y, Cullen, PJ, Lee, NA, Trujillo, FJ, Masood, H, Diao, Y, Cullen, PJ, Lee, NA, and Trujillo, FJ
- Abstract
The performance of three different chamber designs: co-linear, Steinmetz and parallel-plate, for radio frequency electric field (RFEF) processing of liquid foods was evaluated and compared. The study was conducted via a computational model that predicted the electric field, flow, and temperature distribution in those three chambers. The parallel-plate, in spite of having the highest electric field peaks, exhibited not only the most uniform electric field distribution inside the treatment zone but also the most homogenously distributed velocity profile along with the lowest temperature increase and energy consumption. The model was validated by comparing the predicted and experimentally measured outlet temperatures. Experiments of E. coli inactivation were performed in all three chambers at a volumetrically averaged electric field strength of 13.2 kV cm−1, a treatment time of 500 μs and outlet temperatures in the range of 20–50 °C showing equal inactivation given the uncertainties of microbial population quantification methodology.
- Published
- 2018
12. Atmospheric air plasma induces increased cell aggregation during the formation of Escherichia coli biofilms
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Kwandou, G, Mai-Prochnow, A, Prescott, SW, Spicer, PT, Cullen, PJ, Kwandou, G, Mai-Prochnow, A, Prescott, SW, Spicer, PT, and Cullen, PJ
- Abstract
Atmospheric air plasma has previously been shown to be a novel and effective method for biofilm eradication. Here we study the effects of plasma on both microbial inactivation and induced structural modification for forming biofilms. New structures are created from aggregates of extracellular polysaccharides and dead bacterial cells, forming a protective and resilient matrix in which the remaining living cells grow and reproduce under proper growth conditions. The new colonies are found to be more resilient in this state, reducing the efficacy of subsequent plasma treatment. We verify that the observed effect is not caused by chemicals produced by plasma reactive species, but instead by the physical processes of drying and convection caused by the plasma discharge.
- Published
- 2018
13. Numerical and experimental studies on a novel Steinmetz treatment chamber for inactivation of Escherichia coli by radio frequency electric fields
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Masood, H, Razaeimotlagh, A, Cullen, PJ, Trujillo, FJ, Masood, H, Razaeimotlagh, A, Cullen, PJ, and Trujillo, FJ
- Abstract
Radio frequency electric field (RFEF) is an emerging non-thermal food processing technology that is alternative to pulsed electric fields (PEF). A novel Steinmetz treatment chamber design, that increases homogeneity of the electric field distribution, has been proposed and constructed. The design was performed and evaluated via Multiphysics modelling. The model was validated by comparison with experimental measurements of outlet temperature, power consumption and current. Inactivation studies showed the influence of electric field intensity, temperature, and treatment time on the inactivation of Escherichia coli in saline water with electrical conductivities between 0.02 and 0.1 S m− 1. A maximum inactivation of 3.6 log CFU mL− 1 was obtained at 26.5 kV cm− 1, 45 °C and 900 μs treatment time. An energy demand of 63 kJ kg− 1 is required for 1 log reduction, when processing at 25 °C, for foods having 0.1 S m− 1 conductivity at 20 °C, but energy consumption increases with the electrical conductivity.
- Published
- 2017
14. High-resolution mapping of upland swamp vegetation using a unmanned aerial vehicle-hyperspectral system
- Author
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Banerjee, BP, Raval, S, Cullen, PJ, Banerjee, BP, Raval, S, and Cullen, PJ
- Abstract
Mapping of vegetation species and communities in sensitive ecosystems is essential for identification and management of anthropogenic impacts. Unmanned aerial vehicle (UAV)-hyperspectral systems are among the latest technologies in remote sensing that hold a potential for obtaining unprecedented quality of remote sensing data for vegetation mapping and health status monitoring applications. In this study, high-resolution (1–1.5 cm) spectral imaging data (15 bands) from a tunable spectrometer is used to map five species of vegetation in a complex upland swamp environment. The overall accuracy of classification was found to be 88.9% with a kappa coefficient of 0.83. Three classes (bare earth, sedgeland grass and black sheoak) have achieved higher accuracy (above 78%) and one class (bracken fern) has lower accuracy (58%). UAV-hyperspectral technology is, therefore, an effective tool to identify and map sensitive swamp vegetation. The technology can be potentially applied to determine the health status of the species.
- Published
- 2017
15. Non-invasive 3D and 360° optical imaging of micro-particles
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El Arnaout, T, Cullen, PJ, El Arnaout, T, and Cullen, PJ
- Abstract
© 2017 The Author(s). Scanning electron microscopy and X-ray microtomography are useful methods for high resolution shape imaging. Visible microscopy is also common, however, developing a low-cost and customizable system for surface and shape investigation of optically active particles is challenging. In this work, we demonstrate an assembly offering good light sensitivity, flexibility of illumination and contrasts from varying angles. The design was applied, together with recent programs for focus-stacking, to analyze crystals of taurine, L-glutamic acid, acetylsalicylic acid, and copper sulfate, along with digital 3D-360° modelling of phosphorescent [Ru(bpy)3]Cl2and strontium aluminate particles. We further tested the approach for real time monitoring of size, shape and texture analysis of fat filled milk particles and acid whey powders. The findings show proof of concept for detailed feature imaging of particles directly from the process environment.
- Published
- 2017
16. In package inactivation of Bacillus atrophaeus spores using high voltage atmospheric cold plasma
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Patil, Sonal, Keener, Kevin, Moiseev, Tamara, Mosnier, JP, Misra, NN, Cullen, PJ, and Bourke, Paula
- Abstract
Introduction: Hospital acquired infections are of a great concern, considering a large number of infections reported every year. Sterilization is an important step in healthcare industry that is attained by utilizing conventional sterilization approaches. It includes heat treatment, use of chemicals like ethylene oxide, hydrogen peroxide, and gamma radiation. These methods have drawbacks such as material properties of medical devices could be altered or damaged. Therefore, it is necessary to investigate cheap alternative approaches to achieve sterilization without generating toxic residues. Nonthermal atmospheric plasma is a fourth state of matter that consists of charged particles, positive and negative ions and number of reactive species. This plasma mixture has greater microbicidal effects on number of food products and wide range of surfaces. Novel nonthermal plasma technology has number of applications in food and medical industries. Methods: The objective of this study was to investigate the effect of plasma parameters on inactivation of resistant biological forms of Bacillus atrophaeus inside a sealed package. Bacillus atrophaeus spore strip (spore population 6.36 log10/strip) was placed in a petri dish, sealed in a polypropylene container, and was subjected to high voltage atmospheric cold plasma treatment (HVACP). HVACP system was operated at 70 kVRMS and at a frequency of 50 Hz. The two 15-cm diameter aluminum disk electrodes were separated by a rigid polypropylene container which served as a sample holder and as a dielectric barrier. The distance between the two electrodes was equal to the height of the container (22 mm). The top electrode served as a high voltage electrode and bottom electrode was grounded. The discharge was monitored using electrical probes and an Agilent InfiniVision 2000 X-Series Oscilloscope. Influence of different process parameters on spore inactivation including treatment time, mode of exposure (direct/indirect), and working gas types were mainly evaluated. Effect of relative humidity on HVACP inactivation efficacy was also assessed. The inactivation efficacy was determined using standard colony count method. To assess gas composition following HVACP exposure, optical absorption spectroscopy was used. Results: A strong effect of process parameters on inactivation was observed. Direct exposure to plasma was very effective for spore inactivation, achieving ≥6 log cycle reduction of spores in all gas types tested, in only 60 s of treatment time. However, a strong influence of gas type was noted on spore reductions where indirect mode of plasma exposure was utilized. The relative humidity also noted as a critical factor in bacterial spore inactivation by HVACP, where a major role of plasma generated species other than ozone was noted. Conclusion: Overall, a strong influence of process parameters on spore inactivation was noted. Effective in-package bacterial spore inactivation within 30‑60 s demonstrates the promising potential application of HVACP for sterilization of medical devices and heat sensitive materials.
- Published
- 2014
17. Regeneration of Athrotaxis selaginoides and other rainforest tree species on landslide faces in Tasmania
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Cullen, PJ, primary
- Published
- 1991
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18. The ecology of Athrotaxis D. Don (Taxodiaceae) I. Stand structure and regeneration of A. cupressoides
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Cullen, PJ, Kirkpatrick, JB, Cullen, PJ, and Kirkpatrick, JB
- Abstract
Athrotaxis cupressoides forms stands of varying size class and age class structure in the high subalpine and alpine environments of Tasmania. As with some other southern hemisphere gymnosperms with great longevity, A. cupressoides does not successfully regenerate in dense forest stands without disturb- ance but does so in many open stands. Vegetative regeneration through root suckers occurs in many such stands. Suckers are most frequent in bogs and least evident in blockstreams. There has been little successful seedling or sucker regeneration in open stands in the east of the range of the species since European occupation of the Central Plateau. Exclosure experiments and field observations show that seedlings, suckers and adult foliage are heavily grazed by introduced placental and native marsupial mammals.
19. The ecology of Athrotaxis D. Don (Taxodiaceae) II. The distributions and ecological differentiation of A. cupressoides and A. selaginoides
- Author
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Cullen, PJ, Kirkpatrick, JB, Cullen, PJ, and Kirkpatrick, JB
- Abstract
Athrotaxis selaginoides and A. cupressoides are potentially interbreeding species with partly overlapping ranges. The two Athrotaxis species occur in a wide range of floristic types, with A. selaginoides being concentrated in thamnic and implicate rainforest communities and A. cupressoides in open montane communities. As is consonant with its distribution pattern and the cold resistance of its adult foliage, A. cupressoides seedlings are more frost resistant than those of A. selaginoides. Preliminary experiments showed no difference between the two species in resistance to waterlogging or drought. However, stand structure data indicate that A. selaginoides can survive better in shaded conditions than its congenor. This pattern of ecological differentation is consistent with an origin by parapatic speciation.
20. The ecology of Athrotaxis D. Don (Taxodiaceae) I. Stand structure and regeneration of A. cupressoides
- Author
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Cullen, PJ, Kirkpatrick, JB, Cullen, PJ, and Kirkpatrick, JB
- Abstract
Athrotaxis cupressoides forms stands of varying size class and age class structure in the high subalpine and alpine environments of Tasmania. As with some other southern hemisphere gymnosperms with great longevity, A. cupressoides does not successfully regenerate in dense forest stands without disturb- ance but does so in many open stands. Vegetative regeneration through root suckers occurs in many such stands. Suckers are most frequent in bogs and least evident in blockstreams. There has been little successful seedling or sucker regeneration in open stands in the east of the range of the species since European occupation of the Central Plateau. Exclosure experiments and field observations show that seedlings, suckers and adult foliage are heavily grazed by introduced placental and native marsupial mammals.
21. The ecology of Athrotaxis D. Don (Taxodiaceae) II. The distributions and ecological differentiation of A. cupressoides and A. selaginoides
- Author
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Cullen, PJ, Kirkpatrick, JB, Cullen, PJ, and Kirkpatrick, JB
- Abstract
Athrotaxis selaginoides and A. cupressoides are potentially interbreeding species with partly overlapping ranges. The two Athrotaxis species occur in a wide range of floristic types, with A. selaginoides being concentrated in thamnic and implicate rainforest communities and A. cupressoides in open montane communities. As is consonant with its distribution pattern and the cold resistance of its adult foliage, A. cupressoides seedlings are more frost resistant than those of A. selaginoides. Preliminary experiments showed no difference between the two species in resistance to waterlogging or drought. However, stand structure data indicate that A. selaginoides can survive better in shaded conditions than its congenor. This pattern of ecological differentation is consistent with an origin by parapatic speciation.
22. The Ecology of Athrotaxis D. Don (Taxodiaceae). I. Stand Structure and Regeneration of A. cupressoides
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Cullen, PJ, primary and Kirkpatrick, JB, additional
- Published
- 1988
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23. The Ecology of Athrotaxis D. Don (Taxodiaceae). II. The Distributions and Ecological Differentiation of A. Cupressoides and A. selaginoides
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Cullen, PJ, primary and Kirkpatrick, JB, additional
- Published
- 1988
- Full Text
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24. Application of supercritical carbon dioxide to fruit and vegetables: extraction, processing, and preservation
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Rawson, A, Tiwari, BK, Brunton, N, Brennan, CS, Cullen, PJ, and O'Donnell, CP
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- 2012
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25. Development of pilot-scale plasma bubble reactors for efficient antibiotics removal in wastewater.
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Wang S, Liu Z, Li X, Guo H, Zhang Z, Pang B, Gao Y, Cullen PJ, and Zhou R
- Abstract
Plasma bubble (PB) is a promising technology to control antibiotic wastewater pollution. However, the practical implementation of PB technology at the industrial-scale is still underdeveloped. In addition, the influence of different discharge modes for PB on wastewater treatment is largely unknown. This study designed pilot-scale PB reactors with different discharge modes to investigate the degradation effect of norfloxacin (NOR) and tetracycline (TC) in bulk tap water. Results indicate that the dielectric barrier discharge (DBD) mode with low average discharge power demonstrates superior degradation ability and higher production of O
3(g) and. O2 - (aq) compared to the spark mode which exhibits the high-intensity spark discharge in the tip area of the tube. After 40 min of treatment in a Double DBD reactor, 97.4% and 100% of NOR and TC are removed from 2 L tap water, attributed to the accumulation of antibiotic molecules by PBs and the in-situ generation of O3(g) and. O2 - (aq) produced by plasma. Furthermore, a larger-scale PB reactor is developed by creating an array of four DBD reactors, effectively degrading 8 L mixed antibiotics solution. This study provides valuable insights for PB reactor design and the degradation performance of antibiotic wastewater, which will contribute to the further development of synergistic systems for plasma degradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
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26. Conserved signaling modules regulate filamentous growth in fungi: a model for eukaryotic cell differentiation.
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Vandermeulen MD, Lorenz MC, and Cullen PJ
- Subjects
- Signal Transduction, Mitogen-Activated Protein Kinases metabolism, Mitogen-Activated Protein Kinases genetics, Eukaryotic Cells metabolism, Eukaryotic Cells cytology, Models, Biological, Fungal Proteins metabolism, Fungal Proteins genetics, Animals, Cell Differentiation, MAP Kinase Signaling System, Fungi genetics, Fungi metabolism
- Abstract
Eukaryotic organisms are composed of different cell types with defined shapes and functions. Specific cell types are produced by the process of cell differentiation, which is regulated by signal transduction pathways. Signaling pathways regulate cell differentiation by sensing cues and controlling the expression of target genes whose products generate cell types with specific attributes. In studying how cells differentiate, fungi have proved valuable models because of their ease of genetic manipulation and striking cell morphologies. Many fungal species undergo filamentous growth-a specialized growth pattern where cells produce elongated tube-like projections. Filamentous growth promotes expansion into new environments, including invasion into plant and animal hosts by fungal pathogens. The same signaling pathways that regulate filamentous growth in fungi also control cell differentiation throughout eukaryotes and include highly conserved mitogen-activated protein kinase (MAPK) pathways, which is the focus of this review. In many fungal species, mucin-type sensors regulate MAPK pathways to control filamentous growth in response to diverse stimuli. Once activated, MAPK pathways reorganize cell polarity, induce changes in cell adhesion, and promote the secretion of degradative enzymes that mediate access to new environments. However, MAPK pathway regulation is complicated because related pathways can share components with each other yet induce unique responses (i.e. signal specificity). In addition, MAPK pathways function in highly integrated networks with other regulatory pathways (i.e. signal integration). Here, we discuss signal specificity and integration in several yeast models (mainly Saccharomyces cerevisiae and Candida albicans) by focusing on the filamentation MAPK pathway. Because of the strong evolutionary ties between species, a deeper understanding of the regulation of filamentous growth in established models and increasingly diverse fungal species can reveal fundamentally new mechanisms underlying eukaryotic cell differentiation., Competing Interests: Conflicts of interest The authors declare that there are no competing interests with this study. There are no new data associated with this article., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
- Published
- 2024
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27. CHC22 clathrin recruitment to the early secretory pathway requires two-site interaction with SNX5 and p115.
- Author
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Greig J, Bates GT, Yin DI, Briant K, Simonetti B, Cullen PJ, and Brodsky FM
- Subjects
- Humans, Protein Transport, Secretory Pathway, Protein Binding, Golgi Matrix Proteins metabolism, Golgi Matrix Proteins genetics, Golgi Apparatus metabolism, Animals, Clathrin Heavy Chains, Sorting Nexins metabolism, Sorting Nexins genetics, Glucose Transporter Type 4 metabolism, Clathrin metabolism
- Abstract
The two clathrin isoforms, CHC17 and CHC22, mediate separate intracellular transport routes. CHC17 performs endocytosis and housekeeping membrane traffic in all cells. CHC22, expressed most highly in skeletal muscle, shuttles the glucose transporter GLUT4 from the ERGIC (endoplasmic-reticulum-to-Golgi intermediate compartment) directly to an intracellular GLUT4 storage compartment (GSC), from where GLUT4 can be mobilized to the plasma membrane by insulin. Here, molecular determinants distinguishing CHC22 from CHC17 trafficking are defined. We show that the C-terminal trimerization domain of CHC22 interacts with SNX5, which also binds the ERGIC tether p115. SNX5, and the functionally redundant SNX6, are required for CHC22 localization independently of their participation in the endosomal ESCPE-1 complex. In tandem, an isoform-specific patch in the CHC22 N-terminal domain separately mediates binding to p115. This dual mode of clathrin recruitment, involving interactions at both N- and C-termini of the heavy chain, is required for CHC22 targeting to ERGIC membranes to mediate the Golgi-bypass route for GLUT4 trafficking. Interference with either interaction inhibits GLUT4 targeting to the GSC, defining a bipartite mechanism regulating a key pathway in human glucose metabolism., (© 2024. The Author(s).)
- Published
- 2024
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28. Gain- and loss-of-function alleles within signaling pathways lead to phenotypic diversity among individuals.
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Vandermeulen MD, Khaiwal S, Rubio G, Liti G, and Cullen PJ
- Abstract
Understanding how phenotypic diversity is generated is an important question in biology. We explored phenotypic diversity among wild yeast isolates ( Saccharomyces cerevisiae ) and found variation in the activity of MAPK signaling pathways as a contributing mechanism. To uncover the genetic basis of this mechanism, we identified 1957 SNPs in 62 candidate genes encoding signaling proteins from a MAPK signaling module within a large collection of yeast (>1500 individuals). Follow-up testing identified functionally relevant variants in key signaling proteins. Loss-of-function (LOF) alleles in a PAK kinase impacted protein stability and pathway specificity decreasing filamentous growth and mating phenotypes. In contrast, gain-of-function (GOF) alleles in G-proteins that were hyperactivating induced filamentous growth. Similar amino acid substitutions in G-proteins were identified in metazoans that in some cases were fixed in multicellular lineages including humans, suggesting hyperactivating GOF alleles may play roles in generating phenotypic diversity across eukaryotes. A mucin signaler that regulates MAPK activity was also found to contain a prevalance of presumed GOF alleles amoung individuals based on changes in mucin repeat numbers. Thus, genetic variation in signaling pathways may act as a reservoir for generating phenotypic diversity across eukaryotes., Competing Interests: The authors have no competing interests in the study., (© 2024 The Author(s).)
- Published
- 2024
- Full Text
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29. Mechanism and regulation of cargo entry into the Commander endosomal recycling pathway.
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Butkovič R, Walker AP, Healy MD, McNally KE, Liu M, Veenendaal T, Kato K, Liv N, Klumperman J, Collins BM, and Cullen PJ
- Subjects
- Humans, Protein Binding, HeLa Cells, Integrins metabolism, Endosomes metabolism, Sorting Nexins metabolism, Sorting Nexins genetics, Protein Transport
- Abstract
Commander is a multiprotein complex that orchestrates endosomal recycling of integral cargo proteins and is essential for normal development. While the structure of this complex has recently been described, how cargo proteins are selected for Commander-mediated recycling remains unclear. Here we identify the mechanism through which the unstructured carboxy-terminal tail of the cargo adaptor sorting nexin-17 (SNX17) directly binds to the Retriever sub-complex of Commander. SNX17 adopts an autoinhibited conformation where its carboxy-terminal tail occupies the cargo binding groove. Competitive cargo binding overcomes this autoinhibition, promoting SNX17 endosomal residency and the release of the tail for Retriever association. Furthermore, our study establishes the central importance of SNX17-Retriever association in the handover of integrin and lipoprotein receptor cargoes into pre-existing endosomal retrieval sub-domains. In describing the principal mechanism of cargo entry into the Commander recycling pathway we provide key insight into the function and regulation of this evolutionary conserved sorting pathway., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
30. Structural basis for coupling of the WASH subunit FAM21 with the endosomal SNX27-Retromer complex.
- Author
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Guo Q, Chen KE, Gimenez-Andres M, Jellett AP, Gao Y, Simonetti B, Liu M, Danson CM, Heesom KJ, Cullen PJ, and Collins BM
- Subjects
- Humans, Microfilament Proteins metabolism, Microfilament Proteins genetics, Microfilament Proteins chemistry, Protein Binding, Crystallography, X-Ray, Binding Sites, Models, Molecular, Endosomes metabolism, Sorting Nexins metabolism, Sorting Nexins genetics, Sorting Nexins chemistry, Vesicular Transport Proteins metabolism, Vesicular Transport Proteins genetics, Vesicular Transport Proteins chemistry
- Abstract
Endosomal membrane trafficking is mediated by specific protein coats and formation of actin-rich membrane domains. The Retromer complex coordinates with sorting nexin (SNX) cargo adaptors including SNX27, and the SNX27-Retromer assembly interacts with the Wiskott-Aldrich syndrome protein and SCAR homolog (WASH) complex which nucleates actin filaments establishing the endosomal recycling domain. Crystal structures, modeling, biochemical, and cellular validation reveal how the FAM21 subunit of WASH interacts with both Retromer and SNX27. FAM21 binds the FERM domain of SNX27 using acidic-Asp-Leu-Phe (aDLF) motifs similar to those found in the SNX1 and SNX2 subunits of the ESCPE-1 complex. Overlapping FAM21 repeats and a specific Pro-Leu containing motif bind three distinct sites on Retromer involving both the VPS35 and VPS29 subunits. Mutation of the major VPS35-binding site does not prevent cargo recycling; however, it partially reduces endosomal WASH association indicating that a network of redundant interactions promote endosomal activity of the WASH complex. These studies establish the molecular basis for how SNX27-Retromer is coupled to the WASH complex via overlapping and multiplexed motif-based interactions required for the dynamic assembly of endosomal membrane recycling domains., Competing Interests: Competing interests statement:The authors declare no competing interest.
- Published
- 2024
- Full Text
- View/download PDF
31. Modulators of MAPK pathway activity during filamentous growth in Saccharomyces cerevisiae.
- Author
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Pujari AN and Cullen PJ
- Subjects
- Mutation, Gene Expression Regulation, Fungal, Phenotype, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism, MAP Kinase Signaling System, Alleles, Mitogen-Activated Protein Kinases metabolism, Mitogen-Activated Protein Kinases genetics
- Abstract
Mitogen-activated protein kinase (MAPK) pathways control the response to intrinsic and extrinsic stimuli. In the budding yeast Saccharomyces cerevisiae, cells undergo filamentous growth, which is regulated by the fMAPK pathway. To better understand the regulation of the fMAPK pathway, a genetic screen was performed to identify spontaneous mutants with elevated activity of an fMAPK pathway-dependent growth reporter (ste4 FUS1-HIS3). In total, 159 mutants were isolated and analyzed by secondary screens for invasive growth by the plate-washing assay and filament formation by microscopy. Thirty-two mutants were selected for whole-genome sequencing, which identified new alleles in genes encoding known regulators of the fMAPK pathway. These included gain-of-function alleles in STE11, which encodes the MAPKKK, as well as loss-of-function alleles in KSS1, which encodes the MAP kinase, and loss-of-function alleles in RGA1, which encodes a GTPase-activating protein (GAP) for CDC42. New alleles in previously identified pathway modulators were also uncovered in ALY1, AIM44, RCK2, IRA2, REG1, and in genes that regulate protein folding (KAR2), glycosylation (MNN4), and turnover (BLM10). Mutations leading to C-terminal truncations in the transcription factor Ste12p were also uncovered that resulted in elevated reporter activity, identifying an inhibitory domain of the protein from residues 491 to 688. We also find that a diversity of filamentous growth phenotypes can result from combinatorial effects of multiple mutations and by loss of different regulators of the response. The alleles identified here expand the connections surrounding MAPK pathway regulation and reveal new features of proteins that function in the signaling cascade., Competing Interests: Conflicts of interest The author(s) declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)
- Published
- 2024
- Full Text
- View/download PDF
32. Long-Chain Hydrocarbons from Nonthermal Plasma-Driven Biogas Upcycling.
- Author
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Knezevic J, Zhang T, Zhou R, Hong J, Zhou R, Barnett C, Song Q, Gao Y, Xu W, Liu D, Proschogo N, Mohanty B, Strachan J, Soltani B, Li F, Maschmeyer T, Lovell EC, and Cullen PJ
- Abstract
The burgeoning necessity to discover new methodologies for the synthesis of long-chain hydrocarbons and oxygenates, independent of traditional reliance on high-temperature, high-pressure, and fossil fuel-based carbon, is increasingly urgent. In this context, we introduce a nonthermal plasma-based strategy for the initiation and propagation of long-chain carbon growth from biogas constituents (CO
2 and CH4 ). Utilizing a plasma reactor operating at atmospheric room temperature, our approach facilitates hydrocarbon chain growth up to C40 in the solid state (including oxygenated products), predominantly when CH4 exceeds CO2 in the feedstock. This synthesis is driven by the hydrogenation of CO2 and/or amalgamation of CHx radicals. Global plasma chemistry modeling underscores the pivotal role of electron temperature and CHx radical genesis, contingent upon varying CO2 /CH4 ratios in the plasma system. Concomitant with long-chain hydrocarbon production, the system also yields gaseous products, primarily syngas (H2 and CO), as well as liquid-phase alcohols and acids. Our finding demonstrates the feasibility of atmospheric room-temperature synthesis of long-chain hydrocarbons, with the potential for tuning the chain length based on the feed gas composition.- Published
- 2024
- Full Text
- View/download PDF
33. Understanding the endo-lysosomal network in neurodegeneration.
- Author
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Cullen PJ, Holstege H, Small SA, and St George-Hyslop P
- Subjects
- Humans, Lysosomes, Alzheimer Disease
- Published
- 2024
- Full Text
- View/download PDF
34. Retromer-dependent lysosomal stress in Parkinson's disease.
- Author
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Alessi DR, Cullen PJ, Cookson M, Merchant KM, and Small SA
- Subjects
- Humans, Vesicular Transport Proteins genetics, Vesicular Transport Proteins metabolism, Mutation, Lysosomes metabolism, Parkinson Disease genetics, Parkinson Disease metabolism
- Abstract
While causative mutations in complex disorders are rare, they can be used to extract a biological pathway whose pathogenicity can generalize to common forms of the disease. Here we begin by relying on the biological consequences of mutations in LRRK2 and VPS35, genetic causes of autosomal-dominant Parkinson's disease, to hypothesize that 'Retromer-dependent lysosomal stress' represents a pathway that can generalize to idiopathic Parkinson's disease. Next, we outline a series of studies that can test this hypothesis, including the development of biomarkers of pathway dysfunction. If validated, the hypothesis can suggest a unified mechanism of disease and might inform future diagnostic and therapeutic investigations. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.
- Published
- 2024
- Full Text
- View/download PDF
35. Survival of Listeria Strains and Shelf Life Determination of Fresh Blueberries ( Vaccinium corymbosum ) Treated with Cold Atmospheric Plasma.
- Author
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Concha-Meyer AA, González-Esparza A, Cullen PJ, Veloso F, Favre M, Valenzuela JC, Toloza L, and Niemira BA
- Abstract
Fresh blueberries are delicate, hand-picked, packaged, and refrigerated fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology; therefore, this study evaluated the CAP treatment effect on acid-tolerant Listeria innocua and Listeria monocytogenes and evaluated changes in the quality of the treated fruit. Samples were spot-inoculated with pH 5.5 and 6.0 acid-adapted Listeria species. Samples were treated with gliding arc CAP for 15, 30, 45, and 60 s and evaluated after 0, 1, 4, 7, and 11 days of storage at 4 °C and 90% humidity for the following quality parameters: total aerobic counts, yeast and molds, texture, color, soluble solids, pH, and titratable acidity. CAP treatments of 30 s and over demonstrated significant reductions in pathogens under both the resistant strain and pH conditions. Sixty-second CAP achieved a 0.54 Log CFU g
-1 reduction in L. monocytogenes (pH 5.5) and 0.28 Log CFU g-1 for L. monocytogenes (pH 6.0). Yeast and mold counts on day 0 showed statistically significant reductions after 30, 45, and 60 s CAP with an average 2.34 Log CFU g-1 reduction when compared to non-CAP treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.- Published
- 2024
- Full Text
- View/download PDF
36. Catalyst-Free Carbon Dioxide Conversion in Water Facilitated by Pulse Discharges.
- Author
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Zhang T, Knezevic J, Zhu M, Hong J, Zhou R, Song Q, Ding L, Sun J, Liu D, Ostrikov KK, Zhou R, and Cullen PJ
- Abstract
By inducing CO
2 -pulsed discharges within microchannel bubbles and regulating thus-forming plasma microbubbles, we observe high-performance, catalyst-free coformation of hydrogen peroxide (H2 O2 ) and oxalate directly from CO2 and water. With isotope-labeled C18 O2 as the feedstock, peaks of H2 18 O16 O and H2 16 O2 observed by ex situ surface-enhanced Raman spectra indicate that single-atom oxygen (O) from CO2 dissociations and H2 O-derived OH radicals both contribute to H2 O2 formation. The global plasma chemistry modeling suggests that high-density, energy-intense electron supply enables high-density CO2 - (aq) and HCO2 - (aq) formation and their subsequent coupling to produce oxalate. The enhanced solvation of CO2 , facilitated by the efficient transport of Cx Oy ionic species and CO, is demonstrated as a crucial benefit of spark discharges interacting with water at the bubble interface. We expect this plasma microbubble approach to provide a novel power-to-chemical avenue to convert CO2 into valuable H2 O2 and oxalic acid platform chemicals, thus leveraging renewable energy resources.- Published
- 2023
- Full Text
- View/download PDF
37. Modulators of MAPK pathway activity during filamentous growth in Saccharomyces cerevisiae .
- Author
-
Pujari AN and Cullen PJ
- Abstract
Mitogen-activated protein kinase (MAPK) pathways control the response to intrinsic and extrinsic stimuli. In the budding yeast Saccharomyces cerevisiae , cells undergo filamentous growth, which is regulated by the fMAPK pathway. To better understand the regulation of the fMAPK pathway, a genetic screen was performed to identify spontaneous mutants with elevated activity of an fMAPK-pathway dependent growth reporter ( ste4 FUS1-HIS3 ). In total, 159 mutants were isolated and analyzed by secondary screens for invasive growth by the plate-washing assay, and filament formation by microscopy. Thirty-two mutants were selected for whole-genome sequencing, which identified new alleles in genes encoding known regulators of the fMAPK pathway. These included gain-of-function alleles in STE11, which encodes the MAPKKK, as well as loss-of-function alleles in KSS1, which encodes the MAP kinase, and RGA1, which encodes a GTPase activating protein (GAP) for CDC42 . New alleles in previously identified pathway modulators were also uncovered in ALY1, AIM44, RCK2, IRA2, REG1 and in genes that regulate protein folding ( KAR2 ), glycosylation ( MNN4 ), and turnover ( BLM10 ). C-terminal truncations in the transcription factor Ste12p were also uncovered that resulted in elevated reporter activity, presumably identifying an inhibitory domain in the C-terminus of the protein. We also show that a wide variety of filamentous growth phenotypes result from mutations in different regulators of the response. The alleles identified here expand the connections surrounding MAPK pathway regulation and reveal new features of proteins that function in the signaling cascade., Competing Interests: CONFLICT OF INTEREST The authors declare no conflict of interests in the study.
- Published
- 2023
- Full Text
- View/download PDF
38. Turnover and bypass of p21-activated kinase during Cdc42-dependent MAPK signaling in yeast.
- Author
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González B, Mirzaei M, Basu S, Pujari AN, Vandermeulen MD, Prabhakar A, and Cullen PJ
- Subjects
- Intracellular Signaling Peptides and Proteins metabolism, Protein Stability, cdc42 GTP-Binding Protein, Saccharomyces cerevisiae genetics, cdc42 GTP-Binding Protein, Saccharomyces cerevisiae metabolism, Mitogen-Activated Protein Kinases genetics, Mitogen-Activated Protein Kinases metabolism, p21-Activated Kinases genetics, p21-Activated Kinases metabolism, Saccharomyces cerevisiae enzymology, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism
- Abstract
Mitogen-activated protein kinase (MAPK) pathways regulate multiple cellular behaviors, including the response to stress and cell differentiation, and are highly conserved across eukaryotes. MAPK pathways can be activated by the interaction between the small GTPase Cdc42p and the p21-activated kinase (Ste20p in yeast). By studying MAPK pathway regulation in yeast, we recently found that the active conformation of Cdc42p is regulated by turnover, which impacts the activity of the pathway that regulates filamentous growth (fMAPK). Here, we show that Ste20p is regulated in a similar manner and is turned over by the 26S proteasome. This turnover did not occur when Ste20p was bound to Cdc42p, which presumably stabilized the protein to sustain MAPK pathway signaling. Although Ste20p is a major component of the fMAPK pathway, genetic approaches here identified a Ste20p-independent branch of signaling. Ste20p-independent signaling partially required the fMAPK pathway scaffold and Cdc42p-interacting protein, Bem4p, while Ste20p-dependent signaling required the 14-3-3 proteins, Bmh1p and Bmh2p. Interestingly, Ste20p-independent signaling was inhibited by one of the GTPase-activating proteins for Cdc42p, Rga1p, which unexpectedly dampened basal but not active fMAPK pathway activity. These new regulatory features of the Rho GTPase and p21-activated kinase module may extend to related pathways in other systems., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
39. Five Inhibitory Receptors Display Distinct Vesicular Distributions in Murine T Cells.
- Author
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Lu J, Veler A, Simonetti B, Raj T, Chou PH, Cross SJ, Phillips AM, Ruan X, Huynh L, Dowsey AW, Ye D, Murphy RF, Verkade P, Cullen PJ, and Wülfing C
- Subjects
- Mice, Animals, CTLA-4 Antigen metabolism, Carrier Proteins metabolism, Immunotherapy, T-Lymphocytes, Neoplasms metabolism
- Abstract
T cells can express multiple inhibitory receptors. Upon induction of T cell exhaustion in response to a persistent antigen, prominently in the anti-tumor immune response, many are expressed simultaneously. Key inhibitory receptors are CTLA-4, PD-1, LAG3, TIM3, and TIGIT, as investigated here. These receptors are important as central therapeutic targets in cancer immunotherapy. Inhibitory receptors are not constitutively expressed on the cell surface, but substantial fractions reside in intracellular vesicular structures. It remains unresolved to which extent the subcellular localization of different inhibitory receptors is distinct. Using quantitative imaging of subcellular distributions and plasma membrane insertion as complemented by proximity proteomics and biochemical analysis of the association of the inhibitory receptors with trafficking adaptors, the subcellular distributions of the five inhibitory receptors were discrete. The distribution of CTLA-4 was most distinct, with preferential association with lysosomal-derived vesicles and the sorting nexin 1/2/5/6 transport machinery. With a lack of evidence for the existence of specific vesicle subtypes to explain divergent inhibitory receptor distributions, we suggest that such distributions are driven by divergent trafficking through an overlapping joint set of vesicular structures. This extensive characterization of the subcellular localization of five inhibitory receptors in relation to each other lays the foundation for the molecular investigation of their trafficking and its therapeutic exploitation.
- Published
- 2023
- Full Text
- View/download PDF
40. Ecological inducers of the yeast filamentous growth pathway reveal environment-dependent roles for pathway components.
- Author
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Vandermeulen MD and Cullen PJ
- Subjects
- Animals, Signal Transduction, Mitogen-Activated Protein Kinases genetics, Mitogen-Activated Protein Kinases metabolism, Ethanol pharmacology, Carbon metabolism, Saccharomyces cerevisiae metabolism, Galactose
- Abstract
Signaling modules, such as mitogen-activated protein kinase (MAPK) pathways, are evolutionarily conserved drivers of cell differentiation and stress responses. In many fungal species including pathogens, MAPK pathways control filamentous growth, where cells differentiate into an elongated cell type. The convenient model budding yeast Saccharomyces cerevisiae undergoes filamentous growth by the filamentous growth (fMAPK) pathway; however, the inducers of the pathway remain unclear, perhaps because pathway activity has been mainly studied in laboratory conditions. To address this knowledge gap, an ecological framework was used, which uncovered new fMAPK pathway inducers, including pectin, a material found in plants, and the metabolic byproduct ethanol. We also show that induction by a known inducer of the pathway, the non-preferred carbon source galactose, required galactose metabolism and induced the pathway differently than glucose limitation or other non-preferred carbon sources. By exploring fMAPK pathway function in fruit, we found that induction of the pathway led to visible digestion of fruit rind through a known target, PGU1 , which encodes a pectolytic enzyme. Combinations of inducers (galactose and ethanol) stimulated the pathway to near-maximal levels, which showed dispensability of several fMAPK pathway components (e.g., mucin sensor, p21-activated kinase), but not others (e.g., adaptor, MAPKKK) and required the Ras2-protein kinase A pathway. This included a difference between the transcription factor binding partners for the pathway, as Tec1p, but not Ste12p, was partly dispensable for fMAPK pathway activity. Thus, by exploring ecologically relevant stimuli, new modes of MAPK pathway signaling were uncovered, perhaps revealing how a pathway can respond differently to specific environments. IMPORTANCE Filamentous growth is a cell differentiation response and important aspect of fungal biology. In plant and animal fungal pathogens, filamentous growth contributes to virulence. One signaling pathway that regulates filamentous growth is an evolutionarily conserved MAPK pathway. The yeast Saccharomyces cerevisiae is a convenient model to study MAPK-dependent regulation of filamentous growth, although the inducers of the pathway are not clear. Here, we exposed yeast cells to ecologically relevant compounds (e.g., plant compounds), which identified new inducers of the MAPK pathway. In combination, the inducers activated the pathway to near-maximal levels but did not cause detrimental phenotypes associated with previously identified hyperactive alleles. This context allowed us to identify conditional bypass for multiple pathway components. Thus, near-maximal induction of a MAPK pathway by ecologically relevant inducers provides a powerful tool to assess cellular signaling during a fungal differentiation response., Competing Interests: The authors declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
41. Emulsions containing composite (clove, oregano, and cinnamon) essential oils: Phase inversion preparation, physicochemical properties and antibacterial mechanism.
- Author
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Hu J, Zhu H, Feng Y, Yu M, Xu Y, Zhao Y, Zheng B, Lin J, Miao W, Zhou R, and Cullen PJ
- Subjects
- Cinnamomum zeylanicum chemistry, Staphylococcus aureus, Emulsions, Escherichia coli, Anti-Bacterial Agents pharmacology, Microbial Sensitivity Tests, Oils, Volatile pharmacology, Oils, Volatile chemistry, Origanum chemistry, Syzygium
- Abstract
Natural essential oils (EOs), especially those combining different individual EOs (also termed composite EOs) with enhanced performance, are becoming healthy, market-sought food preservatives/additives. This study aims to provide insights into the challenge regarding EOs processing due to their low solubility and the elusive mechanism under the enhanced bio-reactivity of composite EOs. A unique oil/water interacting network was created by phase-inversion processing, which enhances EO solubilization and emulsification to form composite EO formulations (EOFs) containing ordinary cinnamon, oregano and clove EOs. These EOFs mainly contained cinnamaldehyde, carvacrol and eugenol and exhibited excellent post-storage stability. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability of EOFs (at 15.880 μL/mL) was > 88%, and the Ferric reducing antioxidant power (FRAP) was 1.8 mM FeSO
4 ·7H2 O. The minimum inhibitory concentration (MIC) of EOFs against E. coli and S. aureus was ∼7.940 μL/mL. The EOFs could cause quick deterioration of bacterial structures, demonstrating high efficacy in bacteria-killing and anti-biofilm formation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
42. Plasma activated water as a pre-treatment strategy in the context of biofilm-infected chronic wounds.
- Author
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Vyas HKN, Xia B, Alam D, Gracie NP, Rothwell JG, Rice SA, Carter D, Cullen PJ, and Mai-Prochnow A
- Abstract
Healing and treatment of chronic wounds are often complicated due to biofilm formation by pathogens. Here, the efficacy of plasma activated water (PAW) as a pre-treatment strategy has been investigated prior to the application of topical antiseptics polyhexamethylene biguanide, povidone iodine, and MediHoney, which are routinely used to treat chronic wounds. The efficacy of this treatment strategy was determined against biofilms of Escherichia coli formed on a plastic substratum and on a human keratinocyte monolayer substratum used as an in vitro biofilm-skin epithelial cell model. PAW pre-treatment greatly increased the killing efficacy of all the three antiseptics to eradicate the E. coli biofilms formed on the plastic and keratinocyte substrates. However, the efficacy of the combined PAW-antiseptic treatment and single treatments using PAW or antiseptic alone was lower for biofilms formed in the in vitro biofilm-skin epithelial cell model compared to the plastic substratum. Scavenging assays demonstrated that reactive species present within the PAW were largely responsible for its anti-biofilm activity. PAW treatment resulted in significant intracellular reactive oxygen and nitrogen species accumulation within the E. coli biofilms, while also rapidly acting on the microbial membrane leading to outer membrane permeabilisation and depolarisation. Together, these factors contribute to significant cell death, potentiating the antibacterial effect of the assessed antiseptics., Competing Interests: Patrick J. Cullen is the CEO of PlasmaLeap Technologies, the supplier of the plasma power source and BSD reactor utilised in this study., (© 2023 The Authors. Published by Elsevier B.V.)
- Published
- 2023
- Full Text
- View/download PDF
43. An Effective Sanitizer for Fresh Produce Production: In Situ Plasma-Activated Water Treatment Inactivates Pathogenic Bacteria and Maintains the Quality of Cucurbit Fruit.
- Author
-
Rothwell JG, Hong J, Morrison SJ, Vyas HKN, Xia B, Mai-Prochnow A, McConchie R, Phan-Thien KY, Cullen PJ, and Carter DA
- Subjects
- Food Microbiology, Fruit microbiology, Colony Count, Microbial, Food Handling methods, Anti-Infective Agents, Salmonella enterica, Disinfectants pharmacology
- Abstract
The effect of plasma-activated water (PAW) generated with a dielectric barrier discharge diffusor (DBDD) system on microbial load and organoleptic quality of cucamelons was investigated and compared to the established sanitizer, sodium hypochlorite (NaOCl). Pathogenic serotypes of Escherichia coli, Salmonella enterica, and Listeria monocytogenes were inoculated onto the surface of cucamelons (6.5 log CFU g
-1 ) and into the wash water (6 log CFU mL-1 ). PAW treatment involved 2 min in situ with water activated at 1,500 Hz and 120 V and air as the feed gas; NaOCl treatment was a wash with 100 ppm total chlorine; control treatment was a wash with tap water. PAW treatment produced a 3-log CFU g-1 reduction of pathogens on the cucamelon surface without negatively impacting quality or shelf life. NaOCl treatment reduced the pathogenic bacteria on the cucamelon surface by 3 to 4 log CFU g-1 ; however, this treatment also reduced fruit shelf life and quality. Both systems reduced 6-log CFU mL-1 pathogens in the wash water to below detectable limits. The critical role of superoxide anion radical (·O2 - ) in the antimicrobial power of DBDD-PAW was demonstrated through a Tiron scavenger assay, and chemistry modeling confirmed that ·O2 - generation readily occurs in DBDD-PAW generated with the employed settings. Modeling of the physical forces produced during plasma treatment showed that bacteria likely experience strong local electric fields and polarization. We hypothesize that these physical effects synergize with reactive chemical species to produce the acute antimicrobial activity seen with the in situ PAW system. IMPORTANCE Plasma-activated water (PAW) is an emerging sanitizer in the fresh food industry, where food safety must be achieved without a thermal kill step. Here, we demonstrate PAW generated in situ to be a competitive sanitizer technology, providing a significant reduction of pathogenic and spoilage microorganisms while maintaining the quality and shelf life of the produce item. Our experimental results are supported by modeling of the plasma chemistry and applied physical forces, which show that the system can generate highly reactive ·O2 - and strong electric fields that combine to produce potent antimicrobial power. In situ PAW has promise in industrial applications as it requires only low power (12 W), tap water, and air. Moreover, it does not produce toxic by-products or hazardous effluent waste, making it a sustainable solution for fresh food safety., Competing Interests: The authors declare a conflict of interest. P. J. Cullen is the Chief Technology Officer of Plasmaleap Technologies, the supplier of the plasma technology employed to generate plasma bubbles in this study.- Published
- 2023
- Full Text
- View/download PDF
44. Five inhibitory receptors display distinct vesicular distributions in T cells.
- Author
-
Lu J, Veler A, Simonetti B, Raj T, Chou PH, Cross SJ, Phillips AM, Ruan X, Huynh L, Dowsey AW, Ye D, Murphy RF, Verkade P, Cullen PJ, and Wülfing C
- Abstract
T cells can express multiple inhibitory receptors. Upon induction of T cell exhaustion in response to persistent antigen, prominently in the anti-tumor immune response, many are expressed simultaneously. Key inhibitory receptors are CTLA-4, PD-1, LAG3, TIM3 and TIGIT, as investigated here. These receptors are important as central therapeutic targets in cancer immunotherapy. Inhibitory receptors are not constitutively expressed on the cell surface, but substantial fractions reside in intracellular vesicular structures. It remains unresolved to which extent the subcellular localization of different inhibitory receptors is distinct. Using quantitative imaging of subcellular distributions and plasma membrane insertion as complemented by proximity proteomics and a biochemical analysis of the association of the inhibitory receptors with trafficking adaptors, the subcellular distributions of the five inhibitory receptors were discrete. The distribution of CTLA-4 was most distinct with preferential association with lysosomal-derived vesicles and the sorting nexin 1/2/5/6 transport machinery. With a lack of evidence for the existence of specific vesicle subtypes to explain divergent inhibitory receptor distributions, we suggest that such distributions are driven by divergent trafficking through an overlapping joint set of vesicular structures. This extensive characterization of the subcellular localization of five inhibitory receptors in relation to each other lays the foundation for the molecular investigation of their trafficking and its therapeutic exploitation., Competing Interests: Conflicts of Interest The authors declare no conflict of interest.
- Published
- 2023
- Full Text
- View/download PDF
45. Loss of the batten disease protein CLN3 leads to mis-trafficking of M6PR and defective autophagic-lysosomal reformation.
- Author
-
Calcagni' A, Staiano L, Zampelli N, Minopoli N, Herz NJ, Di Tullio G, Huynh T, Monfregola J, Esposito A, Cirillo C, Bajic A, Zahabiyon M, Curnock R, Polishchuk E, Parkitny L, Medina DL, Pastore N, Cullen PJ, Parenti G, De Matteis MA, Grumati P, and Ballabio A
- Subjects
- Humans, Receptor, IGF Type 2 genetics, Receptor, IGF Type 2 metabolism, Proteomics, Molecular Chaperones metabolism, Lysosomes metabolism, Hydrolases metabolism, Autophagy, Membrane Glycoproteins genetics, Membrane Glycoproteins metabolism, Neuronal Ceroid-Lipofuscinoses genetics, Neuronal Ceroid-Lipofuscinoses metabolism
- Abstract
Batten disease, one of the most devastating types of neurodegenerative lysosomal storage disorders, is caused by mutations in CLN3. Here, we show that CLN3 is a vesicular trafficking hub connecting the Golgi and lysosome compartments. Proteomic analysis reveals that CLN3 interacts with several endo-lysosomal trafficking proteins, including the cation-independent mannose 6 phosphate receptor (CI-M6PR), which coordinates the targeting of lysosomal enzymes to lysosomes. CLN3 depletion results in mis-trafficking of CI-M6PR, mis-sorting of lysosomal enzymes, and defective autophagic lysosomal reformation. Conversely, CLN3 overexpression promotes the formation of multiple lysosomal tubules, which are autophagy and CI-M6PR-dependent, generating newly formed proto-lysosomes. Together, our findings reveal that CLN3 functions as a link between the M6P-dependent trafficking of lysosomal enzymes and lysosomal reformation pathway, explaining the global impairment of lysosomal function in Batten disease., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
46. Decapping factor Dcp2 controls mRNA abundance and translation to adjust metabolism and filamentation to nutrient availability.
- Author
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Vijjamarri AK, Niu X, Vandermeulen MD, Onu C, Zhang F, Qiu H, Gupta N, Gaikwad S, Greenberg ML, Cullen PJ, Lin Z, and Hinnebusch AG
- Subjects
- RNA, Messenger genetics, RNA, Messenger metabolism, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae metabolism, RNA Stability genetics, Nonsense Mediated mRNA Decay, Nutrients, Endoribonucleases genetics, Endoribonucleases metabolism, Ribonucleoproteins metabolism, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism
- Abstract
Degradation of most yeast mRNAs involves decapping by Dcp1/Dcp2. DEAD-box protein Dhh1 has been implicated as an activator of decapping, in coupling codon non-optimality to enhanced degradation, and as a translational repressor, but its functions in cells are incompletely understood. RNA-Seq analyses coupled with CAGE sequencing of all capped mRNAs revealed increased abundance of hundreds of mRNAs in dcp2 Δ cells that appears to result directly from impaired decapping rather than elevated transcription. Interestingly, only a subset of mRNAs requires Dhh1 for targeting by Dcp2, and also generally requires the other decapping activators Pat1, Edc3, or Scd6; whereas most of the remaining transcripts utilize nonsense-mediated mRNA decay factors for Dcp2-mediated turnover. Neither inefficient translation initiation nor stalled elongation appears to be a major driver of Dhh1-enhanced mRNA degradation. Surprisingly, ribosome profiling revealed that dcp2 Δ confers widespread changes in relative translational efficiencies (TEs) that generally favor well-translated mRNAs. Because ribosome biogenesis is reduced while capped mRNA abundance is increased by dcp2 Δ , we propose that an increased ratio of mRNA to ribosomes increases competition among mRNAs for limiting ribosomes to favor efficiently translated mRNAs in dcp2 Δ cells. Interestingly, genes involved in respiration or utilization of alternative carbon or nitrogen sources are upregulated, and both mitochondrial function and cell filamentation are elevated in dcp2 Δ cells, suggesting that decapping sculpts gene expression post-transcriptionally to fine-tune metabolic pathways and morphological transitions according to nutrient availability., Competing Interests: AV, XN, MV, CO, FZ, HQ, NG, SG, MG, PC, ZL No competing interests declared, AH Reviewing editor, eLife
- Published
- 2023
- Full Text
- View/download PDF
47. The antimicrobial effects of mist spraying and immersion on beef samples with plasma-activated water.
- Author
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Hadinoto K, Yang H, Zhang T, Cullen PJ, Prescott S, and Trujillo FJ
- Subjects
- Animals, Cattle, Humans, Immersion, Meat, Temperature, Colony Count, Microbial, Food Microbiology, Water chemistry, Anti-Infective Agents
- Abstract
The use of plasma-activated water (PAW) as an antimicrobial agent to inactivate Salmonella Typhimurium on chilled beef during meat washing was evaluated. Two meat washing methods, spraying and immersion, were evaluated at contact times of 15, 30 and 60 s and meat storage times of 0, 1 and 7 days. The temperature of PAW was elevated to 55 °C for washing as it increased the microbial inactivation compared to ambient temperature. At the contact time of 60 s and meat storage time of 7 days, PAW spraying and immersion achieved 0.737-log
10 and 0.710-log10 reductions against Salmonella Typhimurium, respectively; there were no significant differences between both washing methods, with spraying being preferred for commercial implementation. Compared to untreated and water-treated samples, meat washing with PAW alone improved the S. Typhimurium inactivation and did not cause negative impacts on the lightness and hue angle values, TBARS value, water holding capacity and pH. However, PAW reduced the redness, yellowness and chroma values with the decreased oxymyoglobin values of 44.1% at the storage time of 1 day. PAW spraying at 55 °C followed by additional water washing at 25 °C for 60 s achieved 0.696-log10 reduction and mitigated a reduction in (i) the redness value, from 11.3 to 18.2, (ii) the yellowness value, from 9.19 to 11.1, and (iii) the chroma value, from 14.5 to 21.3, without displaying colour differences (∆E), as detected by human eyes, compared to water-treated samples. Moreover, the content of myoglobin forms was maintained by additional water washing., Competing Interests: Declaration of Competing Interest Author Patrick J. Cullen is the CEO of PlasmaLeap Technologies, the supplier of the Leap100 power supply and bubble reactors used in this study., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
48. Out of the ESCPE room: Emerging roles of endosomal SNX-BARs in receptor transport and host-pathogen interaction.
- Author
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Simonetti B, Daly JL, and Cullen PJ
- Subjects
- Humans, trans-Golgi Network metabolism, Salmonella typhimurium metabolism, Chlamydia trachomatis metabolism, Viruses metabolism, Protein Transport, Host-Pathogen Interactions, Sorting Nexins metabolism, Endosomes metabolism, Multiprotein Complexes metabolism, Receptors, Cell Surface metabolism
- Abstract
Several functions of the human cell, such as sensing nutrients, cell movement and interaction with the surrounding environment, depend on a myriad of transmembrane proteins and their associated proteins and lipids (collectively termed "cargoes"). To successfully perform their tasks, cargo must be sorted and delivered to the right place, at the right time, and in the right amount. To achieve this, eukaryotic cells have evolved a highly organized sorting platform, the endosomal network. Here, a variety of specialized multiprotein complexes sort cargo into itineraries leading to either their degradation or their recycling to various organelles for further rounds of reuse. A key sorting complex is the Endosomal SNX-BAR Sorting Complex for Promoting Exit (ESCPE-1) that promotes the recycling of an array of cargos to the plasma membrane and/or the trans-Golgi network. ESCPE-1 recognizes a hydrophobic-based sorting motif in numerous cargoes and orchestrates their packaging into tubular carriers that pinch off from the endosome and travel to the target organelle. A wide range of pathogens mimic this sorting motif to hijack ESCPE-1 transport to promote their invasion and survival within infected cells. In other instances, ESCPE-1 exerts restrictive functions against pathogens by limiting their replication and infection. In this review, we discuss ESCPE-1 assembly and functions, with a particular focus on recent advances in the understanding of its role in membrane trafficking, cellular homeostasis and host-pathogen interaction., (© 2023 The Authors. Traffic published by John Wiley & Sons Ltd.)
- Published
- 2023
- Full Text
- View/download PDF
49. Multi-omic approach characterises the neuroprotective role of retromer in regulating lysosomal health.
- Author
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Daly JL, Danson CM, Lewis PA, Zhao L, Riccardo S, Di Filippo L, Cacchiarelli D, Lee D, Cross SJ, Heesom KJ, Xiong WC, Ballabio A, Edgar JR, and Cullen PJ
- Subjects
- Humans, Proteome metabolism, Proteomics, Endosomes metabolism, Protein Transport physiology, Lysosomes metabolism, Neuroprotection, Multiomics
- Abstract
Retromer controls cellular homeostasis through regulating integral membrane protein sorting and transport and by controlling maturation of the endo-lysosomal network. Retromer dysfunction, which is linked to neurodegenerative disorders including Parkinson's and Alzheimer's diseases, manifests in complex cellular phenotypes, though the precise nature of this dysfunction, and its relation to neurodegeneration, remain unclear. Here, we perform an integrated multi-omics approach to provide precise insight into the impact of Retromer dysfunction on endo-lysosomal health and homeostasis within a human neuroglioma cell model. We quantify widespread changes to the lysosomal proteome, indicative of broad lysosomal dysfunction and inefficient autophagic lysosome reformation, coupled with a reconfigured cell surface proteome and secretome reflective of increased lysosomal exocytosis. Through this global proteomic approach and parallel transcriptomic analysis, we provide a holistic view of Retromer function in regulating lysosomal homeostasis and emphasise its role in neuroprotection., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
50. Structure of the endosomal Commander complex linked to Ritscher-Schinzel syndrome.
- Author
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Healy MD, McNally KE, Butkovič R, Chilton M, Kato K, Sacharz J, McConville C, Moody ERR, Shaw S, Planelles-Herrero VJ, Yadav SKN, Ross J, Borucu U, Palmer CS, Chen KE, Croll TI, Hall RJ, Caruana NJ, Ghai R, Nguyen THD, Heesom KJ, Saitoh S, Berger I, Schaffitzel C, Williams TA, Stroud DA, Derivery E, Collins BM, and Cullen PJ
- Subjects
- Humans, Endosomes metabolism, Protein Transport, Proteins metabolism, Abnormalities, Multiple, Craniofacial Abnormalities, Multiprotein Complexes metabolism
- Abstract
The Commander complex is required for endosomal recycling of diverse transmembrane cargos and is mutated in Ritscher-Schinzel syndrome. It comprises two sub-assemblies: Retriever composed of VPS35L, VPS26C, and VPS29; and the CCC complex which contains twelve subunits: COMMD1-COMMD10 and the coiled-coil domain-containing (CCDC) proteins CCDC22 and CCDC93. Combining X-ray crystallography, electron cryomicroscopy, and in silico predictions, we have assembled a complete structural model of Commander. Retriever is distantly related to the endosomal Retromer complex but has unique features preventing the shared VPS29 subunit from interacting with Retromer-associated factors. The COMMD proteins form a distinctive hetero-decameric ring stabilized by extensive interactions with CCDC22 and CCDC93. These adopt a coiled-coil structure that connects the CCC and Retriever assemblies and recruits a 16th subunit, DENND10, to form the complete Commander complex. The structure allows mapping of disease-causing mutations and reveals the molecular features required for the function of this evolutionarily conserved trafficking machinery., Competing Interests: Declaration of interests The authors declare that they have no conflicts of interest., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
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