1
|
Zhou L, Na J, Liu X, Wu P. Chromophore-Assisted Light Inactivation for Protein Degradation and Its Application in Biomedicine. Bioengineering (Basel) 2024; 11:651. [PMID: 39061733 PMCID: PMC11273424 DOI: 10.3390/bioengineering11070651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/28/2024] Open
Abstract
The functional investigation of proteins holds immense significance in unraveling physiological and pathological mechanisms of organisms as well as advancing the development of novel pharmaceuticals in biomedicine. However, the study of cellular protein function using conventional genetic manipulation methods may yield unpredictable outcomes and erroneous conclusions. Therefore, precise modulation of protein activity within cells holds immense significance in the realm of biomedical research. Chromophore-assisted light inactivation (CALI) is a technique that labels photosensitizers onto target proteins and induces the production of reactive oxygen species through light control to achieve precise inactivation of target proteins. Based on the type and characteristics of photosensitizers, different excitation light sources and labeling methods are selected. For instance, KillerRed forms a fusion protein with the target protein through genetic engineering for labeling and inactivates the target protein via light activation. CALI is presently predominantly employed in diverse biomedical domains encompassing investigations into protein functionality and interaction, intercellular signal transduction research, as well as cancer exploration and therapy. With the continuous advancement of CALI technology, it is anticipated to emerge as a formidable instrument in the realm of life sciences, yielding more captivating outcomes for fundamental life sciences and precise disease diagnosis and treatment.
Collapse
Affiliation(s)
- Lvjia Zhou
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-Targeting Theranostics, Guangxi Key Laboratory of Bio-Targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning 530021, China; (L.Z.); (J.N.)
| | - Jintong Na
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-Targeting Theranostics, Guangxi Key Laboratory of Bio-Targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning 530021, China; (L.Z.); (J.N.)
| | - Xiyu Liu
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-Targeting Theranostics, Guangxi Key Laboratory of Bio-Targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning 530021, China; (L.Z.); (J.N.)
| | - Pan Wu
- State Key Laboratory of Targeting Oncology, National Center for International Research of Bio-Targeting Theranostics, Guangxi Key Laboratory of Bio-Targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning 530021, China; (L.Z.); (J.N.)
- School of Pharmacy, Guangxi Medical University, Nanning 530021, China
| |
Collapse
|
2
|
Hahn KM, Itano MS, Loew LM, Vitriol EA. Celebrating the creative scientific life of Ken Jacobson. Biophys J 2023; 122:E1-E4. [PMID: 37643609 PMCID: PMC10541490 DOI: 10.1016/j.bpj.2023.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 08/15/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Affiliation(s)
- Klaus M Hahn
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michelle S Itano
- Department of Cell Biology & Physiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Leslie M Loew
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Eric A Vitriol
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia.
| |
Collapse
|
3
|
Hakeem RM, Subramanian BC, Hockenberry MA, King ZT, Butler MT, Legant WR, Bear JE. A Photopolymerized Hydrogel System with Dual Stiffness Gradients Reveals Distinct Actomyosin-Based Mechano-Responses in Fibroblast Durotaxis. ACS NANO 2023; 17:197-211. [PMID: 36475639 PMCID: PMC9839609 DOI: 10.1021/acsnano.2c05941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Durotaxis, migration of cells directed by a stiffness gradient, is critical in development and disease. To distinguish durotaxis-specific migration mechanisms from those on uniform substrate stiffnesses, we engineered an all-in-one photopolymerized hydrogel system containing areas of stiffness gradients with dual slopes (steep and shallow), adjacent to uniform stiffness (soft and stiff) regions. While fibroblasts rely on nonmuscle myosin II (NMII) activity and the LIM-domain protein Zyxin, ROCK and the Arp2/3 complex are surprisingly dispensable for durotaxis on either stiffness gradient. Additionally, loss of either actin-elongator Formin-like 3 (FMNL3) or actin-bundler fascin has little impact on durotactic response on stiffness gradients. However, lack of Arp2/3 activity results in a filopodia-based durotactic migration that is equally as efficient as that of lamellipodia-based durotactic migration. Importantly, we uncover essential and specific roles for FMNL3 and fascin in the formation and asymmetric distribution of filopodia during filopodia-based durotaxis response to the stiffness gradients. Together, our tunable all-in-one hydrogel system serves to identify both conserved as well as distinct molecular mechanisms that underlie mechano-responses of cells experiencing altered slopes of stiffness gradients.
Collapse
Affiliation(s)
- Reem M Hakeem
- Department of Biochemistry and Biophysics, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Bhagawat C Subramanian
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Max A Hockenberry
- Department of Cell Biology and Physiology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- Department of Pharmacology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Zayna T King
- Department of Cell Biology and Physiology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Mitchell T Butler
- Department of Cell Biology and Physiology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Wesley R Legant
- Department of Pharmacology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - James E Bear
- Department of Cell Biology and Physiology, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
- UNC Lineberger Comprehensive Cancer Center, UNC-Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| |
Collapse
|
4
|
Myers KR, Fan Y, McConnell P, Cooper JA, Zheng JQ. Actin capping protein regulates postsynaptic spine development through CPI-motif interactions. Front Mol Neurosci 2022; 15:1020949. [PMID: 36245917 PMCID: PMC9557104 DOI: 10.3389/fnmol.2022.1020949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/12/2022] [Indexed: 12/02/2022] Open
Abstract
Dendritic spines are small actin-rich protrusions essential for the formation of functional circuits in the mammalian brain. During development, spines begin as dynamic filopodia-like protrusions that are then replaced by relatively stable spines containing an expanded head. Remodeling of the actin cytoskeleton plays a key role in the formation and modification of spine morphology, however many of the underlying regulatory mechanisms remain unclear. Capping protein (CP) is a major actin regulating protein that caps the barbed ends of actin filaments, and promotes the formation of dense branched actin networks. Knockdown of CP impairs the formation of mature spines, leading to an increase in the number of filopodia-like protrusions and defects in synaptic transmission. Here, we show that CP promotes the stabilization of dendritic protrusions, leading to the formation of stable mature spines. However, the localization and function of CP in dendritic spines requires interactions with proteins containing a capping protein interaction (CPI) motif. We found that the CPI motif-containing protein Twinfilin-1 (Twf1) also localizes to spines where it plays a role in CP spine enrichment. The knockdown of Twf1 leads to an increase in the density of filopodia-like protrusions and a decrease in the stability of dendritic protrusions, similar to CP knockdown. Finally, we show that CP directly interacts with Shank and regulates its spine accumulation. These results suggest that spatiotemporal regulation of CP in spines not only controls the actin dynamics underlying the formation of stable postsynaptic spine structures, but also plays an important role in the assembly of the postsynaptic apparatus underlying synaptic function.
Collapse
Affiliation(s)
- Kenneth R. Myers
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Yanjie Fan
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Patrick McConnell
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, MO, United States
| | - John A. Cooper
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, MO, United States
| | - James Q. Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA, United States
| |
Collapse
|
5
|
King ZT, Butler MT, Hockenberry MA, Subramanian BC, Siesser PF, Graham DM, Legant WR, Bear JE. Coro1B and Coro1C regulate lamellipodia dynamics and cell motility by tuning branched actin turnover. J Cell Biol 2022; 221:e202111126. [PMID: 35657370 PMCID: PMC9170525 DOI: 10.1083/jcb.202111126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/01/2022] [Accepted: 05/18/2022] [Indexed: 02/03/2023] Open
Abstract
Actin filament dynamics must be precisely controlled in cells to execute behaviors such as vesicular trafficking, cytokinesis, and migration. Coronins are conserved actin-binding proteins that regulate several actin-dependent subcellular processes. Here, we describe a new conditional knockout cell line for two ubiquitous coronins, Coro1B and Coro1C. These coronins, which strongly co-localize with Arp2/3-branched actin, require Arp2/3 activity for proper subcellular localization. Coronin null cells have altered lamellipodial protrusion dynamics due to increased branched actin density and reduced actin turnover within lamellipodia, leading to defective haptotaxis. Surprisingly, excessive cofilin accumulates in coronin null lamellipodia, a result that is inconsistent with the current models of coronin-cofilin functional interaction. However, consistent with coronins playing a pro-cofilin role, coronin null cells have increased F-actin levels. Lastly, we demonstrate that the loss of coronins increases accompanied by an increase in cellular contractility. Together, our observations reveal that coronins are critical for proper turnover of branched actin networks and that decreased actin turnover leads to increased cellular contractility.
Collapse
Affiliation(s)
- Zayna T. King
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - Mitchell T. Butler
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - Max A. Hockenberry
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- Department of Pharmacology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - Bhagawat C. Subramanian
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - Priscila F. Siesser
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - David M. Graham
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - Wesley R. Legant
- Department of Pharmacology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| | - James E. Bear
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
- Department of Pharmacology, University of North Carolina-Chapel Hill School of Medicine, Chapel Hill, NC
| |
Collapse
|
6
|
Ullo MF, Logue JS. ADF and cofilin-1 collaborate to promote cortical actin flow and the leader bleb-based migration of confined cells. eLife 2021; 10:67856. [PMID: 34169836 PMCID: PMC8253594 DOI: 10.7554/elife.67856] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/22/2021] [Indexed: 01/16/2023] Open
Abstract
Melanoma cells have been shown to undergo fast amoeboid (leader bleb-based) migration, requiring a single large bleb for migration. In leader blebs, is a rapid flow of cortical actin that drives the cell forward. Using RNAi, we find that co-depleting cofilin-1 and actin depolymerizing factor (ADF) led to a large increase in cortical actin, suggesting that both proteins regulate cortical actin. Furthermore, severing factors can promote contractility through the regulation of actin architecture. However, RNAi of cofilin-1 but not ADF led to a significant decrease in cell stiffness. We found cofilin-1 to be enriched at leader bleb necks, whereas RNAi of cofilin-1 and ADF reduced bleb sizes and the frequency of motile cells. Strikingly, cells without cofilin-1 and ADF had blebs with abnormally long necks. Many of these blebs failed to retract and displayed slow actin turnover. Collectively, our data identifies cofilin-1 and ADF as actin remodeling factors required for fast amoeboid migration.
Collapse
Affiliation(s)
- Maria F Ullo
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, United States
| | - Jeremy S Logue
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, United States
| |
Collapse
|
7
|
Furger C. Live Cell Assays for the Assessment of Antioxidant Activities of Plant Extracts. Antioxidants (Basel) 2021; 10:antiox10060944. [PMID: 34208019 PMCID: PMC8230623 DOI: 10.3390/antiox10060944] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/31/2021] [Accepted: 06/09/2021] [Indexed: 12/21/2022] Open
Abstract
Plant extracts and pharmacopoeias represent an exceptional breeding ground for the discovery of new antioxidants. Until recently, the antioxidant activity was only measured by chemical hydrogen atom transfer (HAT) and single-electron transfer (SET) cell-free assays that do not inform about the actual effect of antioxidants in living systems. By providing information about the mode of action of antioxidants at the subcellular level, recently developed live cell assays are now changing the game. The idea of this review is to present the different cell-based approaches allowing a quantitative measurement of antioxidant effects of plant extracts. Up to date, only four different approaches have reached a certain degree of standardization: (1) the catalase-like assay using H2O2 as a stressor, (2) the cell antioxidant assay (CAA) using AAPH as a stressor and DCFH-DA as a readout, (3) the AOP1 assay which uses photoinduction to monitor and control cell ROS production, and (4) the Nrf2/ARE gene reporter system. The molecular aspects of these assays are presented in detail along with their features, drawbacks, and benefits. The Nrf2/ARE gene reporter system dedicated to indirect antioxidant effect measurement currently represents the most standardized approach with high-throughput applications. AOP1, the first technology linking a fine-tuning of cell ROS production with a quantitative signal, appears to be the most promising tool for the assessment of direct cellular ROS-scavenging effects at an industrial scale.
Collapse
Affiliation(s)
- Christophe Furger
- Anti Oxidant Power AOP/MH2F-LAAS/CNRS, 7 Avenue du Colonel Roche, BP 54200, 31031 Toulouse, France
| |
Collapse
|
8
|
Binns TC, Ayala AX, Grimm JB, Tkachuk AN, Castillon GA, Phan S, Zhang L, Brown TA, Liu Z, Adams SR, Ellisman MH, Koyama M, Lavis LD. Rational Design of Bioavailable Photosensitizers for Manipulation and Imaging of Biological Systems. Cell Chem Biol 2020; 27:1063-1072.e7. [PMID: 32698018 PMCID: PMC7483975 DOI: 10.1016/j.chembiol.2020.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/04/2020] [Accepted: 06/29/2020] [Indexed: 01/14/2023]
Abstract
Light-mediated chemical reactions are powerful methods for manipulating and interrogating biological systems. Photosensitizers, compounds that generate reactive oxygen species upon excitation with light, can be utilized for numerous biological experiments, but the repertoire of bioavailable photosensitizers is limited. Here, we describe the synthesis, characterization, and utility of two photosensitizers based upon the widely used rhodamine scaffold and demonstrate their efficacy for chromophore-assisted light inactivation, cell ablation in culture and in vivo, and photopolymerization of diaminobenzidine for electron microscopy. These chemical tools will facilitate a broad range of applications spanning from targeted destruction of proteins to high-resolution imaging.
Collapse
Affiliation(s)
- Thomas C Binns
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA; Graduate School, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Anthony X Ayala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ariana N Tkachuk
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Guillaume A Castillon
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Sebastien Phan
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Lixia Zhang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Timothy A Brown
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Stephen R Adams
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Minoru Koyama
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
| |
Collapse
|
9
|
Tagliatela AC, Hempstead SC, Hibshman PS, Hockenberry MA, Brighton HE, Pecot CV, Bear JE. Coronin 1C inhibits melanoma metastasis through regulation of MT1-MMP-containing extracellular vesicle secretion. Sci Rep 2020; 10:11958. [PMID: 32686704 PMCID: PMC7371684 DOI: 10.1038/s41598-020-67465-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/05/2020] [Indexed: 02/06/2023] Open
Abstract
Coronin 1C is overexpressed in multiple tumors, leading to the widely held view that this gene drives tumor progression, but this hypothesis has not been rigorously tested in melanoma. Here, we combined a conditional knockout of Coronin 1C with a genetically engineered mouse model of PTEN/BRAF-driven melanoma. Loss of Coronin 1C in this model increases both primary tumor growth rates and distant metastases. Coronin 1C-null cells isolated from this model are more invasive in vitro and produce more metastatic lesions in orthotopic transplants than Coronin 1C-reexpressing cells due to the shedding of extracellular vesicles (EVs) containing MT1-MMP. Interestingly, these vesicles contain melanosome markers suggesting a melanoma-specific mechanism of EV release, regulated by Coronin 1C, that contributes to the high rates of metastasis in melanoma.
Collapse
Affiliation(s)
- Alicia C Tagliatela
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Stephanie C Hempstead
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Priya S Hibshman
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Max A Hockenberry
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Hailey E Brighton
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Chad V Pecot
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Division of Hematology and Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - James E Bear
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| |
Collapse
|
10
|
Trewin AJ, Berry BJ, Wei AY, Bahr LL, Foster TH, Wojtovich AP. Light-induced oxidant production by fluorescent proteins. Free Radic Biol Med 2018; 128:157-164. [PMID: 29425690 PMCID: PMC6078816 DOI: 10.1016/j.freeradbiomed.2018.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/22/2018] [Accepted: 02/02/2018] [Indexed: 10/18/2022]
Abstract
Oxidants play an important role in the cell and are involved in many redox processes. Oxidant concentrations are maintained through coordinated production and removal systems. The dysregulation of oxidant homeostasis is a hallmark of many disease pathologies. The local oxidant microdomain is crucial for the initiation of many redox signaling events; however, methods to control oxidant product are limited. Some fluorescent proteins, including GFP, TagRFP, KillerRed, miniSOG, and their derivatives, generate oxidants in response to light. These genetically-encoded photosensitizers produce singlet oxygen and superoxide upon illumination and offer spatial and temporal control over oxidant production. In this review, we will examine the photosensitization properties of fluorescent proteins and their application to redox biology. Emerging concepts of selective oxidant species production via photosensitization and the impact of light on biological systems are discussed.
Collapse
Affiliation(s)
- Adam J Trewin
- University of Rochester Medical Center, Department of Anesthesiology and Perioperative Medicine, Rochester 14642, United States
| | - Brandon J Berry
- University of Rochester Medical Center, Department of Pharmacology and Physiology, Rochester 14642, United States
| | - Alicia Y Wei
- University of Rochester Medical Center, Department of Anesthesiology and Perioperative Medicine, Rochester 14642, United States
| | - Laura L Bahr
- University of Rochester Medical Center, Department of Anesthesiology and Perioperative Medicine, Rochester 14642, United States
| | - Thomas H Foster
- University of Rochester Medical Center, Department of Imaging Sciences, Rochester 14642, United States
| | - Andrew P Wojtovich
- University of Rochester Medical Center, Department of Anesthesiology and Perioperative Medicine, Rochester 14642, United States; University of Rochester Medical Center, Department of Pharmacology and Physiology, Rochester 14642, United States.
| |
Collapse
|
11
|
Riani YD, Matsuda T, Takemoto K, Nagai T. Green monomeric photosensitizing fluorescent protein for photo-inducible protein inactivation and cell ablation. BMC Biol 2018; 16:50. [PMID: 29712573 PMCID: PMC5928576 DOI: 10.1186/s12915-018-0514-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/06/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Photosensitizing fluorescent proteins, which generate reactive oxygen species (ROS) upon light irradiation, are useful for spatiotemporal protein inactivation and cell ablation. They give us clues about protein function, intracellular signaling pathways and intercellular interactions. Since ROS generation of a photosensitizer is specifically controlled by certain excitation wavelengths, utilizing colour variants of photosensitizing protein would allow multi-spatiotemporal control of inactivation. To expand the colour palette of photosensitizing protein, here we developed SuperNova Green from its red predecessor, SuperNova. RESULTS SuperNova Green is able to produce ROS spatiotemporally upon blue light irradiation. Based on protein characterization, SuperNova Green produces insignificant amounts of singlet oxygen and predominantly produces superoxide and its derivatives. We utilized SuperNova Green to specifically inactivate the pleckstrin homology domain of phospholipase C-δ1 and to ablate cancer cells in vitro. As a proof of concept for multi-spatiotemporal control of inactivation, we demonstrate that SuperNova Green can be used with its red variant, SuperNova, to perform independent protein inactivation or cell ablation studies in a spatiotemporal manner by selective light irradiation. CONCLUSION Development of SuperNova Green has expanded the photosensitizing protein toolbox to optogenetically control protein inactivation and cell ablation.
Collapse
Affiliation(s)
- Yemima Dani Riani
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan
| | - Tomoki Matsuda
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan.,The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka, Ibaraki, 567-0047, Japan
| | - Kiwamu Takemoto
- Graduate School of Medicine, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama, 236-0027, Japan
| | - Takeharu Nagai
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan. .,The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka, Ibaraki, 567-0047, Japan.
| |
Collapse
|
12
|
Tyrosine dephosphorylated cortactin downregulates contractility at the epithelial zonula adherens through SRGAP1. Nat Commun 2017; 8:790. [PMID: 28983097 PMCID: PMC5629210 DOI: 10.1038/s41467-017-00797-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 07/20/2017] [Indexed: 11/25/2022] Open
Abstract
Contractile adherens junctions support cell−cell adhesion, epithelial integrity, and morphogenesis. Much effort has been devoted to understanding how contractility is established; however, less is known about whether contractility can be actively downregulated at junctions nor what function this might serve. We now identify such an inhibitory pathway that is mediated by the cytoskeletal scaffold, cortactin. Mutations of cortactin that prevent its tyrosine phosphorylation downregulate RhoA signaling and compromise the ability of epithelial cells to generate a contractile zonula adherens. This is mediated by the RhoA antagonist, SRGAP1. We further demonstrate that this mechanism is co-opted by hepatocyte growth factor to promote junctional relaxation and motility in epithelial collectives. Together, our findings identify a novel function of cortactin as a regulator of RhoA signaling that can be utilized by morphogenetic regulators for the active downregulation of junctional contractility. Epithelial cell-cell adhesions are contractile junctions, but whether contractility can be down-regulated is not known. Here the authors report how tyrosine dephosphorylation of the cytoskeletal scaffold, cortactin, recruits the RhoA antagonist SRGAP1 to relax adherens junctions in response to HGF.
Collapse
|
13
|
di Pietro F, Valon L, Li Y, Goïame R, Genovesio A, Morin X. An RNAi Screen in a Novel Model of Oriented Divisions Identifies the Actin-Capping Protein Z β as an Essential Regulator of Spindle Orientation. Curr Biol 2017; 27:2452-2464.e8. [PMID: 28803871 DOI: 10.1016/j.cub.2017.06.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/06/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022]
Abstract
Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. We developed a new cellular model of oriented cell divisions combining micropatterning and localized recruitment of Gαi and performed an RNAi screen for regulators acting downstream of Gαi. Remarkably, this screen revealed a unique subset of dynein regulators as being essential for spindle orientation, shedding light on a core regulatory aspect of oriented divisions. We further analyze the involvement of one novel regulator, the actin-capping protein CAPZB. Mechanistically, we show that CAPZB controls spindle orientation independently of its classical role in the actin cytoskeleton by regulating the assembly, stability, and motor activity of the dynein/dynactin complex at the cell cortex, as well as the dynamics of mitotic microtubules. Finally, we show that CAPZB controls planar divisions in vivo in the developing neuroepithelium. This demonstrates the power of this in cellulo model of oriented cell divisions to uncover new genes required in spindle orientation in vertebrates.
Collapse
Affiliation(s)
- Florencia di Pietro
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Sorbonne Universités, UPMC Université Paris 06, IFD, 4 Place Jussieu, 75252 Paris, France
| | - Léo Valon
- Laboratoire Physico-Chimie, Institut Curie, PSL Research University, CNRS, UPMC Université Paris 06, 75005 Paris, France
| | - Yingbo Li
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France; Scientific Center for Computational Biology, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Rosette Goïame
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Auguste Genovesio
- Scientific Center for Computational Biology, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France
| | - Xavier Morin
- Cell Division and Neurogenesis, IBENS, Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, 75005 Paris, France.
| |
Collapse
|
14
|
Long MJC, Poganik JR, Ghosh S, Aye Y. Subcellular Redox Targeting: Bridging in Vitro and in Vivo Chemical Biology. ACS Chem Biol 2017; 12:586-600. [PMID: 28068059 DOI: 10.1021/acschembio.6b01148] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Networks of redox sensor proteins within discrete microdomains regulate the flow of redox signaling. Yet, the inherent reactivity of redox signals complicates the study of specific redox events and pathways by traditional methods. Herein, we review designer chemistries capable of measuring flux and/or mimicking subcellular redox signaling at the cellular and organismal level. Such efforts have begun to decipher the logic underlying organelle-, site-, and target-specific redox signaling in vitro and in vivo. These data highlight chemical biology as a perfect gateway to interrogate how nature choreographs subcellular redox chemistry to drive precision redox biology.
Collapse
Affiliation(s)
- Marcus J. C. Long
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Jesse R. Poganik
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Souradyuti Ghosh
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Yimon Aye
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14850, United States
- Department
of Biochemistry, Weill Cornell Medicine, New York, New York 10065, United States
| |
Collapse
|
15
|
McMillen LM, Vavylonis D. Model of turnover kinetics in the lamellipodium: implications of slow- and fast- diffusing capping protein and Arp2/3 complex. Phys Biol 2016; 13:066009. [PMID: 27922825 DOI: 10.1088/1478-3975/13/6/066009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cell protrusion through polymerization of actin filaments at the leading edge of motile cells may be influenced by spatial gradients of diffuse actin and regulators. Here we study the distribution of two of the most important regulators, capping protein and Arp2/3 complex, which regulate actin polymerization in the lamellipodium through capping and nucleation of free barbed ends. We modeled their kinetics using data from prior single molecule microscopy experiments on XTC cells. These experiments have provided evidence for a broad distribution of diffusion coefficients of both capping protein and Arp2/3 complex. The slowly diffusing proteins appear as extended 'clouds' while proteins bound to the actin filament network appear as speckles that undergo retrograde flow. Speckle appearance and disappearance events correspond to assembly and dissociation from the actin filament network and speckle lifetimes correspond to the dissociation rate. The slowly diffusing capping protein could represent severed capped actin filament fragments or membrane-bound capping protein. Prior evidence suggests that slowly diffusing Apr2/3 complex associates with the membrane. We use the measured rates and estimates of diffusion coefficients of capping protein and Arp2/3 complex in a Monte Carlo simulation that includes particles in association with a filament network and diffuse in the cytoplasm. We consider two separate pools of diffuse proteins, representing fast and slowly diffusing species. We find a steady state with concentration gradients involving a balance of diffusive flow of fast and slow species with retrograde flow. We show that simulations of FRAP are consistent with prior experiments performed on different cell types. We provide estimates for the ratio of bound to diffuse complexes and calculate conditions where Arp2/3 complex recycling by diffusion may become limiting. We discuss the implications of slowly diffusing populations and suggest experiments to distinguish among mechanisms that influence long range transport.
Collapse
Affiliation(s)
- Laura M McMillen
- Department of Physics, Lehigh University, Bethlehem PA 18015, USA
| | | |
Collapse
|
16
|
Pélissier-Monier A, Sanson B, Monier B. Performing Chromophore-Assisted Laser Inactivation in Drosophila Embryos Using GFP. Methods Mol Biol 2016; 1478:161-176. [PMID: 27730580 DOI: 10.1007/978-1-4939-6371-3_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Chromophore-assisted laser inactivation (CALI) is an optogenetic technique in which light-induced release of reactive oxygen species triggers acute inactivation of a protein of interest, with high spatial and temporal resolution. At its simplest, selective protein inactivation can be achieved via the genetic fusion of the protein to a photosensitizer such as EGFP, and using standard optical setups such as laser scanning confocal microscopes. Although use of CALI in Drosophila is relatively recent, this technique can be a powerful complement to developmental genetics, especially in vivo as it allows visualization of the immediate consequences of local protein inactivation when coupled to time-lapse microscopy analysis. In addition to providing examples of protocols, this chapter is intended as a conceptual framework to support the rational design of CALI experiments.
Collapse
Affiliation(s)
- Anne Pélissier-Monier
- Université Toulouse III-Paul Sabatier, 118 route de Narbonne, 31062, Toulouse, France
- CNRS, UMR5547, Centre de Biologie du Développement, 31062, Toulouse, France
| | - Bénédicte Sanson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge, CB2 3DY, UK.
| | - Bruno Monier
- Université Toulouse III-Paul Sabatier, 118 route de Narbonne, 31062, Toulouse, France
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération, CNRS, UMR5088, 31062, Toulouse, France
| |
Collapse
|
17
|
Gomez GA, McLachlan RW, Wu SK, Caldwell BJ, Moussa E, Verma S, Bastiani M, Priya R, Parton RG, Gaus K, Sap J, Yap AS. An RPTPα/Src family kinase/Rap1 signaling module recruits myosin IIB to support contractile tension at apical E-cadherin junctions. Mol Biol Cell 2015; 26:1249-62. [PMID: 25631816 PMCID: PMC4454173 DOI: 10.1091/mbc.e14-07-1223] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cell-cell adhesion couples the contractile cortices of epithelial cells together, generating tension to support a range of morphogenetic processes. E-cadherin adhesion plays an active role in generating junctional tension by promoting actin assembly and cortical signaling pathways that regulate myosin II. Multiple myosin II paralogues accumulate at mammalian epithelial cell-cell junctions. Earlier, we found that myosin IIA responds to Rho-ROCK signaling to support junctional tension in MCF-7 cells. Although myosin IIB is also found at the zonula adherens (ZA) in these cells, its role in junctional contractility and its mode of regulation are less well understood. We now demonstrate that myosin IIB contributes to tension at the epithelial ZA. Further, we identify a receptor type-protein tyrosine phosphatase alpha-Src family kinase-Rap1 pathway as responsible for recruiting myosin IIB to the ZA and supporting contractile tension. Overall these findings reinforce the concept that orthogonal E-cadherin-based signaling pathways recruit distinct myosin II paralogues to generate the contractile apparatus at apical epithelial junctions.
Collapse
Affiliation(s)
- Guillermo A Gomez
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Robert W McLachlan
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Selwin K Wu
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Benjamin J Caldwell
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Elliott Moussa
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Suzie Verma
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Michele Bastiani
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Rashmi Priya
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Robert G Parton
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | - Katharina Gaus
- UNSW Australia, ARC Centre of Excellence in Advanced Molecular Imaging and Australian Centre for Nanomedicine, Sydney 2052, Australia
| | - Jan Sap
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216 CNRS Bâtiment Lamarck, F-75205 Paris Cedex 13, France
| | - Alpha S Yap
- Division of Cell Biology and Molecular Medicine, Institute for Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| |
Collapse
|
18
|
Sano Y, Watanabe W, Matsunaga S. Chromophore-assisted laser inactivation--towards a spatiotemporal-functional analysis of proteins, and the ablation of chromatin, organelle and cell function. J Cell Sci 2014; 127:1621-9. [PMID: 24737873 DOI: 10.1242/jcs.144527] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chromophore-assisted laser or light inactivation (CALI) has been employed as a promising technique to achieve spatiotemporal knockdown or loss-of-function of target molecules in situ. CALI is performed using photosensitizers as generators of reactive oxygen species (ROS). There are two CALI approaches that use either transgenic tags with chemical photosensitizers, or genetically encoded fluorescent protein fusions. Using spatially restricted microscopy illumination, CALI can address questions regarding, for example, protein isoforms, subcellular localization or phase-specific analyses of multifunctional proteins that other knockdown approaches, such as RNA interference or treatment with chemicals, cannot. Furthermore, rescue experiments can clarify the phenotypic capabilities of CALI after the depletion of endogenous targets. CALI can also provide information about individual events that are involved in the function of a target protein and highlight them in multifactorial events. Beyond functional analysis of proteins, CALI of nuclear proteins can be performed to induce cell cycle arrest, chromatin- or locus-specific DNA damage. Even at organelle level - such as in mitochondria, the plasma membrane or lysosomes - CALI can trigger cell death. Moreover, CALI has emerged as an optogenetic tool to switch off signaling pathways, including the optical depletion of individual neurons. In this Commentary, we review recent applications of CALI and discuss the utility and effective use of CALI to address open questions in cell biology.
Collapse
Affiliation(s)
- Yukimi Sano
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | | | | |
Collapse
|
19
|
Henson JH, Gianakas AD, Henson LH, Lakin CL, Voss MK, Bewersdorf J, Oldenbourg R, Morris RL. Broadening the spectrum of actin-based protrusive activity mediated by Arp2/3 complex-facilitated polymerization: motility of cytoplasmic ridges and tubular projections. Cytoskeleton (Hoboken) 2014; 71:484-500. [PMID: 25111797 DOI: 10.1002/cm.21186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 06/19/2014] [Accepted: 07/21/2014] [Indexed: 11/08/2022]
Abstract
Arp2/3 complex-facilitated actin polymerization plays an essential role in a variety of cellular functions including motility, adherence, endocytosis, and trafficking. In the present study, we employ the sea urchin coelomocyte experimental model system to test the hypotheses that Arp2/3 complex-nucleated actin assembly mediates the motility of two unusual cellular protrusions; the cytoplasmic ridges present during coelomocyte spreading, and inducible, tubular-shaped, and neurite-like projections. Our investigations couple pharmacological manipulation employing inhibitors of actin polymerization and the Arp2/3 complex with a wide array of imaging methods including digitally enhanced phase contrast, DIC, and polarization light microscopy of live cells; conventional, confocal and super-resolution light microscopy of fluorescently labeled cells; and scanning and transmission electron microscopy. Taken together, the results of this study indicate that Arp2/3 complex-facilitated actin polymerization underlies the motility of coelomocyte cytoplasmic ridges and tubular projections, that these processes are related to each other, and that they have been preliminarily identified in other cell types. The results also highlight the broad spectrum of actin-based protrusive activities dependent on the Arp2/3 complex and provide additional insights into the pervasive nature of this ubiquitous actin nucleator. Furthermore, we provide the first evidence of a possible mechanistic difference between the impacts of the small molecule drugs BDM and CK666 on the Arp2/3 complex.
Collapse
Affiliation(s)
- John H Henson
- Department of Biology, Dickinson College, Carlisle, Pennsylvania; Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; Marine Biological Laboratory, Woods Hole, Massachusetts
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Luo L, Wall AA, Yeo JC, Condon ND, Norwood SJ, Schoenwaelder S, Chen KW, Jackson S, Jenkins BJ, Hartland EL, Schroder K, Collins BM, Sweet MJ, Stow JL. Rab8a interacts directly with PI3Kγ to modulate TLR4-driven PI3K and mTOR signalling. Nat Commun 2014; 5:4407. [PMID: 25022365 DOI: 10.1038/ncomms5407] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/16/2014] [Indexed: 02/06/2023] Open
Abstract
Toll-like receptor 4 (TLR4) is activated by bacterial lipopolysaccharide (LPS) to mount innate immune responses. The TLR4-induced release of pro- and anti-inflammatory cytokines generates robust inflammatory responses, which must then be restrained to avoid disease. New mechanisms for the critical regulation of TLR-induced cytokine responses are still emerging. Here we find TLR4 complexes localized in LPS-induced dorsal ruffles on the surface of macrophages. We discover that the small GTPase Rab8a is enriched in these ruffles and recruits phosphatidylinositol 3-kinase (PI3Kγ) as an effector by interacting directly through its Ras-binding domain. Rab8a and PI3Kγ function to regulate Akt signalling generated by surface TLR4. Rab8a and PI3Kγ do not affect TLR4 endocytosis, but instead regulate mammalian target of rapamycin signalling as a mechanism for biasing the cytokine profile to constrain inflammation in innate immunity.
Collapse
Affiliation(s)
- Lin Luo
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia [2]
| | - Adam A Wall
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia [2]
| | - Jeremy C Yeo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Suzanne J Norwood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Simone Schoenwaelder
- 1] Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia [2] Heart Research Institute & Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kaiwen W Chen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Shaun Jackson
- 1] Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia [2] Heart Research Institute & Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Brendan J Jenkins
- Centre for Innate Immunity and Infectious Diseases, MIMR-PHI Institute of Medical Research, Monash University, 27-31 Wright Street, Clayton, Victoria 3168, Australia
| | - Elizabeth L Hartland
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria 3010, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| |
Collapse
|
21
|
Zhang JF, Dong LJ, Jiang W, Zhang H, Ding WF, Zhou GX, Mao ZB. Effect of up-regulation of CDX2 expression on miRNA expression profiles and biological behavior in gastric cancer SGC-7901 cells. Shijie Huaren Xiaohua Zazhi 2013; 21:2241-2249. [DOI: 10.11569/wcjd.v21.i23.2241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To screen differentially expressed miRNAs in human gastric carcinoma cells with up-regulated caudal type homeobox gene 2 (CDX2) expression and to analyze their effect on biological behavior of cells.
METHODS: A recombinant eukaryotic expression plasmid carrying the CDX2 gene was constructed. SGC-7901 cells were divided into three groups: non-transfected cells, cells transfected with PEGFP-N1 or PEGFP-N1-CDX2. The expression of GFP was observed by fluorescent microscopy. Expression of CDX2 mRNA and EGFP-CDX2 fusion protein was detected by qRT-PCR and Western blot, respectively. Cell proliferation was measured using CCK8 assay. In vitro cell migration and adhesion were measured by cell scratch assay, Transwell assay and cell adhesion assay. Differentially expressed miRNAs were detected using a miRNA chip, and their target genes were forecasted using Miranda, TargetScan and Mirtarget2 software.
RESULTS: The eukaryotic expression vector PEGFP-N1-CDX2 was successfully constructed. The expression levels of CDX2 mRNA and protein were higher in SGC-7901 transfected with PEGFP-N1-CDX2 than in control cells. In SGC-7901 cells transfected with PEGFP-N1-CDX2, cell proliferation, invasion and adhesion were significantly inhibited (all P < 0.05) compared with non-transfected cell or cells transfected with PEGFP-N1. Of 59 identified differentially expressed miRNAs between cells transfected PEGFP-N1-CDX2 and those transfected with PEGFP-N1, 25 had > 2-fold up-regulation and 34 had > 2-fold down-regulation in cells transfected with PEGFP-N1-CDX2. Many target genes of these differentially expressed miRNAs were predicted using miRNA target predication tools.
CONCLUSION: Up-regulation of CDX2 expression inhibits the growth, migration and adhesion of SGC-7901 cells. The antitumor effect of CDX2 may be associated with miRNA expression.
Collapse
|
22
|
Vitriol EA, Wise AL, Berginski ME, Bamburg JR, Zheng JQ. Instantaneous inactivation of cofilin reveals its function of F-actin disassembly in lamellipodia. Mol Biol Cell 2013; 24:2238-47. [PMID: 23676663 PMCID: PMC3708729 DOI: 10.1091/mbc.e13-03-0156] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/01/2013] [Accepted: 05/08/2013] [Indexed: 12/23/2022] Open
Abstract
Cofilin is a key regulator of the actin cytoskeleton. It can sever actin filaments, accelerate filament disassembly, act as a nucleation factor, recruit or antagonize other actin regulators, and control the pool of polymerization-competent actin monomers. In cells these actions have complex functional outputs. The timing and localization of cofilin activity are carefully regulated, and thus global, long-term perturbations may not be sufficient to probe its precise function. To better understand cofilin's spatiotemporal action in cells, we implemented chromophore-assisted laser inactivation (CALI) to instantly and specifically inactivate it. In addition to globally inhibiting actin turnover, CALI of cofilin generated several profound effects on the lamellipodia, including an increase of F-actin, a rearward expansion of the actin network, and a reduction in retrograde flow speed. These results support the hypothesis that the principal role of cofilin in lamellipodia at steady state is to break down F-actin, control filament turnover, and regulate the rate of retrograde flow.
Collapse
Affiliation(s)
- Eric A. Vitriol
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Ariel L. Wise
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Mathew E. Berginski
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - James R. Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - James Q. Zheng
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| |
Collapse
|
23
|
Priya R, Yap AS, Gomez GA. E-cadherin supports steady-state Rho signaling at the epithelial zonula adherens. Differentiation 2013; 86:133-40. [PMID: 23643492 DOI: 10.1016/j.diff.2013.01.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/14/2013] [Accepted: 01/15/2013] [Indexed: 11/15/2022]
Abstract
In simple polarized epithelial cells, the Rho GTPase commonly localizes to E-cadherin-based cell-cell junctions, such as the zonula adherens (ZA), where it regulates the actomyosin cytoskeleton to support junctional integrity and tension. An important question is how E-cadherin contributes to Rho signaling, notably whether junctional Rho may depend on cadherin adhesion. We sought to investigate this by assessing Rho localization and activity in epithelial monolayers depleted of E-cadherin by RNAi. We report that E-cadherin depletion reduced both Rho and Rho-GTP at the ZA, an effect that was rescued by expressing a RNAi-resistant full-length E-cadherin transgene. This impact on Rho signaling was accompanied by reduced junctional localization of the Rho GEF ECT2 and the centralspindlin complex that recruits ECT2. Further, the Rho signaling pathway contributes to the selective stabilization of E-cadherin molecules in the apical zone of the cells compared with E-cadherin at the lateral surface, thereby creating a more defined and restricted pool of E-cadherin that forms the ZA. Thus, E-cadherin and Rho signaling cooperate to ensure proper ZA architecture and function.
Collapse
Affiliation(s)
- Rashmi Priya
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | | | | |
Collapse
|
24
|
Chan KT, Jones SW, Brighton HE, Bo T, Cochran SD, Sharpless NE, Bear JE. Intravital imaging of a spheroid-based orthotopic model of melanoma in the mouse ear skin. INTRAVITAL 2013; 2. [PMID: 28748125 DOI: 10.4161/intv.25805] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Multiphoton microscopy is a powerful tool that enables the visualization of fluorescently tagged tumor cells and their stromal interactions within tissues in vivo. We have developed an orthotopic model of implanting multicellular melanoma tumor spheroids into the dermis of the mouse ear skin without the requirement for invasive surgery. Here, we demonstrate the utility of this approach to observe the primary tumor, single cell actin dynamics, and tumor-associated vasculature. These methods can be broadly applied to investigate an array of biological questions regarding tumor cell behavior in vivo.
Collapse
Affiliation(s)
- Keefe T Chan
- Department of Cell Biology and Physiology; Howard Hughes Medical Institute, Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| | - Stephen W Jones
- Department of Cell Biology and Physiology; Howard Hughes Medical Institute, Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| | - Hailey E Brighton
- Department of Cell Biology and Physiology; Howard Hughes Medical Institute, Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| | - Tao Bo
- Department of Cell Biology and Physiology; Howard Hughes Medical Institute, Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| | - Shelly D Cochran
- Department of Biomedical Engineering; North Carolina State University; Raleigh, NC USA
| | - Norman E Sharpless
- Departments of Genetics and Medicine; Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| | - James E Bear
- Department of Cell Biology and Physiology; Howard Hughes Medical Institute, Lineberger Comprehensive Cancer Center; University of North Carolina-Chapel Hill; Chapel Hill, NC USA
| |
Collapse
|
25
|
Prakash J, Kodanko JJ. Metal-based methods for protein inactivation. Curr Opin Chem Biol 2013; 17:197-203. [DOI: 10.1016/j.cbpa.2012.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 11/29/2012] [Accepted: 12/07/2012] [Indexed: 01/16/2023]
|
26
|
Chong H, Zhu C, Song J, Feng L, Yang Q, Liu L, Lv F, Wang S. Preparation and Optical Property of New Fluorescent Nanoparticles. Macromol Rapid Commun 2013; 34:736-42. [DOI: 10.1002/marc.201200755] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Revised: 01/18/2013] [Indexed: 01/06/2023]
|
27
|
Rab6a/a' are important Golgi regulators of pro-inflammatory TNF secretion in macrophages. PLoS One 2013; 8:e57034. [PMID: 23437303 PMCID: PMC3578815 DOI: 10.1371/journal.pone.0057034] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/16/2013] [Indexed: 02/06/2023] Open
Abstract
Lipopolysaccharide (LPS)-activated macrophages secrete pro-inflammatory cytokines, including tumor necrosis factor (TNF) to elicit innate immune responses. Secretion of these cytokines is also a major contributing factor in chronic inflammatory disease. In previous studies we have begun to elucidate the pathways and molecules that mediate the intracellular trafficking and secretion of TNF. Rab6a and Rab6a' (collectively Rab6) are trans-Golgi-localized GTPases known for roles in maintaining Golgi structure and Golgi-associated trafficking. We found that induction of TNF secretion by LPS promoted the selective increase of Rab6 expression. Depletion of Rab6 (via siRNA and shRNA) resulted in reorganization of the Golgi ribbon into more compact structures that at the resolution of electron microcopy consisted of elongated Golgi stacks that likely arose from fusion of smaller Golgi elements. Concomitantly, the delivery of TNF to the cell surface and subsequent release into the media was reduced. Dominant negative mutants of Rab6 had similar effects in disrupting TNF secretion. In live cells, Rab6-GFP were localized on trans-Golgi network (TGN)-derived tubular carriers demarked by the golgin p230. Rab6 depletion and inactive mutants altered carrier egress and partially reduced p230 membrane association. Our results show that Rab6 acts on TNF trafficking at the level of TGN exit in tubular carriers and our findings suggest Rab6 may stabilize p230 on the tubules to facilitate TNF transport. Both Rab6 isoforms are needed in macrophages for Golgi stack organization and for the efficient post-Golgi transport of TNF. This work provides new insights into Rab6 function and into the role of the Golgi complex in cytokine secretion in inflammatory macrophages.
Collapse
|
28
|
Priya R, Gomez G. Measurement of Junctional Protein Dynamics Using Fluorescence Recovery After Photobleaching (FRAP). Bio Protoc 2013. [DOI: 10.21769/bioprotoc.937] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
|
29
|
Gach PC, Xu W, King SJ, Sims CE, Bear J, Allbritton NL. Microfabricated arrays for splitting and assay of clonal colonies. Anal Chem 2012; 84:10614-20. [PMID: 23153031 PMCID: PMC3525785 DOI: 10.1021/ac301895t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A microfabricated platform was developed for highly parallel and efficient colony picking, splitting, and clone identification. A pallet array provided patterned cell colonies which mated to a second printing array composed of bridging microstructures formed by a supporting base and attached post. The posts enabled mammalian cells from colonies initially cultured on the pallet array to migrate to corresponding sites on the printing array. Separation of the arrays simultaneously split the colonies, creating a patterned replica. Optimization of array elements provided transfer efficiencies greater than 90% using bridging posts of 30 μm diameter and 100 μm length and total colony numbers of 3000. Studies using five mammalian cell lines demonstrated that a variety of adherent cell types could be cultured and effectively split with printing efficiencies of 78-92%. To demonstrate the technique's utility, clonal cell lines with siRNA knockdown of Coronin 1B were generated using the arrays and compared to a traditional FACS/Western Blotting-based approach. Identification of target clones required a destructive assay to identify cells with an absence of Coronin 1B brought about by the successful infection of interfering shRNA construct. By virtue of miniaturization and its parallel format, the platform enabled the identification and generation of 12 target clones from a starting sample of only 3900 cells and required only 5 man hours over 11 days. In contrast, the traditional method required 500,000 cells and generated only 5 target clones with 34 man hours expended over 47 days. These data support the considerable reduction in time, manpower, and reagents using the miniaturized platform for clonal selection by destructive assay versus conventional approaches.
Collapse
Affiliation(s)
- Philip C. Gach
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Wei Xu
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Samantha J. King
- Department of Cell & Development Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Christopher E. Sims
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - James Bear
- Department of Cell & Development Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Nancy L. Allbritton
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599 and North Carolina State University, Raleigh, NC 27695
| |
Collapse
|
30
|
Abstract
Chromophore-assisted laser inactivation (CALI) is a technique that uses photochemically-generated reactive oxygen species to acutely inactivate target proteins in living cells. Neural development includes highly dynamic cellular processes such as asymmetric cell division, migration, axon and dendrite outgrowth and synaptogenesis. Although many key molecules of neural development have been identified since the past decades, their spatiotemporal contributions to these cellular events are not well understood. CALI provides an appealing tool for elucidating the precise functions of these molecules during neural development. In this review, we summarize the principles of CALI, a recent microscopic setup to perform CALI experiments, and the application of CALI to the study of growth-cone motility and neuroblast asymmetric division.
Collapse
Affiliation(s)
- Wei Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | | | | |
Collapse
|
31
|
CD2AP links cortactin and capping protein at the cell periphery to facilitate formation of lamellipodia. Mol Cell Biol 2012; 33:38-47. [PMID: 23090967 DOI: 10.1128/mcb.00734-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Understanding the physiology of complex relationships between components of signaling pathways and the actin cytoskeleton is an important challenge. CD2AP is a membrane scaffold protein implicated in a variety of physiological and disease processes. The physiological function of CD2AP is unclear, but its biochemical interactions suggest that it has a role in dynamic actin assembly. Here, we report that CD2AP functions to facilitate the recruitment of actin capping protein (CP) to the Src kinase substrate, cortactin, at the cell periphery, and that this is necessary for formation of the short branched filaments that characterize lamellipodium formation and are required for cell migration. Superresolution fluorescence microscopy demonstrated that the efficient colocalization of CP and cortactin at the cell periphery required CD2AP. As both cortactin and CP function to enhance branched actin filament formation, CD2AP functions synergistically to enhance the function of both proteins. Our data demonstrate how the interplay between specialized actin regulatory molecules shapes the actin cytoskeleton.
Collapse
|
32
|
Abstract
Dynamic rearrangement of actin filament networks is critical for cell motility, phagocytosis and endocytosis. Coronins facilitate these processes, in part, by their ability to bind F-actin (filamentous actin). We previously identified a conserved surface-exposed arginine (Arg30) in the β-propeller of Coronin 1B required for F-actin binding in vitro and in vivo. However, whether this finding translates to other coronins has not been well defined. Using quantitative actin-binding assays, we show that mutating the equivalent residue abolishes F-actin binding in Coronin 1A, but not Coronin 1C. By mutagenesis and biochemical competition, we have identified a second actin-binding site in the unique region of Coronin 1C. Interestingly, leading-edge localization of Coronin 1C in fibroblasts requires the conserved site in the β-propeller, but not the site in the unique region. Furthermore, in contrast with Coronin 1A and Coronin 1B, Coronin 1C displays highly co-operative binding to actin filaments. In the present study, we highlight a novel mode of coronin regulation, which has implications for how coronins orchestrate cytoskeletal dynamics.
Collapse
|
33
|
Centralspindlin and α-catenin regulate Rho signalling at the epithelial zonula adherens. Nat Cell Biol 2012; 14:818-828. [PMID: 22750944 DOI: 10.1038/ncb2532] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 05/25/2012] [Indexed: 12/17/2022]
Abstract
The biological impact of Rho depends critically on the precise subcellular localization of its active, GTP-loaded form. This can potentially be determined by the balance between molecules that promote nucleotide exchange or GTP hydrolysis. However, how these activities may be coordinated is poorly understood. We now report a molecular pathway that achieves exactly this coordination at the epithelial zonula adherens. We identify an extramitotic activity of the centralspindlin complex, better understood as a cytokinetic regulator, which localizes to the interphase zonula adherens by interacting with the cadherin-associated protein, α-catenin. Centralspindlin recruits the RhoGEF, ECT2, to activate Rho and support junctional integrity through myosin IIA. Centralspindlin also inhibits the junctional localization of p190 B RhoGAP, which can inactivate Rho. Thus, a conserved molecular ensemble that governs Rho activation during cytokinesis is used in interphase cells to control the Rho GTPase cycle at the zonula adherens.
Collapse
|
34
|
Baumgart F, Rossi A, Verkman AS. Light inactivation of water transport and protein-protein interactions of aquaporin-Killer Red chimeras. ACTA ACUST UNITED AC 2012; 139:83-91. [PMID: 22200949 PMCID: PMC3250104 DOI: 10.1085/jgp.201110712] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aquaporins (AQPs) have a broad range of cellular and organ functions; however, nontoxic inhibitors of AQP water transport are not available. Here, we applied chromophore-assisted light inactivation (CALI) to inhibit the water permeability of AQP1, and of two AQP4 isoforms (M1 and M23), one of which (M23) forms aggregates at the cell plasma membrane. Chimeras containing Killer Red (KR) and AQPs were generated with linkers of different lengths. Osmotic water permeability of cells expressing KR/AQP chimeras was measured from osmotic swelling-induced dilution of cytoplasmic chloride, which was detected using a genetically encoded chloride-sensing fluorescent protein. KR-AQP1 red fluorescence was bleached rapidly (~10% per second) by wide-field epifluorescence microscopy. After KR bleaching, KR-AQP1 water permeability was reduced by up to 80% for the chimera with the shortest linker. Remarkably, CALI-induced reduction in AQP4-KR water permeability was approximately twice as efficient for the aggregate-forming M23 isoform; this suggests intermolecular CALI, which was confirmed by native gel electrophoresis on cells coexpressing M23-AQP4-KR and myc-tagged M23-AQP4. CALI also disrupted the interaction of AQP4 with a neuromyelitis optica autoantibody directed against an extracellular epitope on AQP4. CALI thus permits rapid, spatially targeted and irreversible reduction in AQP water permeability and interactions in live cells. Our data also support the utility of CALI to study protein-protein interactions as well as other membrane transporters and receptors.
Collapse
Affiliation(s)
- Florian Baumgart
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | | | | |
Collapse
|
35
|
Vitriol EA, Zheng JQ. Growth cone travel in space and time: the cellular ensemble of cytoskeleton, adhesion, and membrane. Neuron 2012; 73:1068-81. [PMID: 22445336 DOI: 10.1016/j.neuron.2012.03.005] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2012] [Indexed: 10/28/2022]
Abstract
Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of the neural circuitry. To date, many families of conserved guidance molecules and their corresponding receptors have been identified that work in space and time to ensure billions of axons to reach their targets. Research in the past two decades has also gained significant insight into the ways in which growth cones translate extracellular signals into directional migration. This review aims to examine new progress toward understanding the cellular mechanisms underlying directional motility of the growth cone and to discuss questions that remain to be addressed. Specifically, we will focus on the cellular ensemble of cytoskeleton, adhesion, and membrane and examine how the intricate interplay between these processes orchestrates the directed movement of growth cones.
Collapse
Affiliation(s)
- Eric A Vitriol
- Department of Cell Biology and Neurology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
| | | |
Collapse
|
36
|
Wu C, Asokan SB, Berginski ME, Haynes EM, Sharpless NE, Griffith JD, Gomez SM, Bear JE. Arp2/3 is critical for lamellipodia and response to extracellular matrix cues but is dispensable for chemotaxis. Cell 2012; 148:973-87. [PMID: 22385962 PMCID: PMC3707508 DOI: 10.1016/j.cell.2011.12.034] [Citation(s) in RCA: 371] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/28/2011] [Accepted: 12/21/2011] [Indexed: 02/06/2023]
Abstract
Lamellipodia are sheet-like, leading edge protrusions in firmly adherent cells that contain Arp2/3-generated dendritic actin networks. Although lamellipodia are widely believed to be critical for directional cell motility, this notion has not been rigorously tested. Using fibroblasts derived from Ink4a/Arf-deficient mice, we generated a stable line depleted of Arp2/3 complex that lacks lamellipodia. This line shows defective random cell motility and relies on a filopodia-based protrusion system. Utilizing a microfluidic gradient generation system, we tested the role of Arp2/3 complex and lamellipodia in directional cell migration. Surprisingly, Arp2/3-depleted cells respond normally to shallow gradients of PDGF, indicating that lamellipodia are not required for fibroblast chemotaxis. Conversely, these cells cannot respond to a surface-bound gradient of extracellular matrix (haptotaxis). Consistent with this finding, cells depleted of Arp2/3 fail to globally align focal adhesions, suggesting that one principle function of lamellipodia is to organize cell-matrix adhesions in a spatially coherent manner.
Collapse
Affiliation(s)
- Congying Wu
- Dept of Cell & Developmental Biology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Sreeja B. Asokan
- Dept of Cell & Developmental Biology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Matthew E. Berginski
- Depts of Biomedical Engineering, Computer Science and Pharmacology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Elizabeth M. Haynes
- Dept of Cell & Developmental Biology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Norman E. Sharpless
- Dept of Genetics, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Jack D. Griffith
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Dept of Biochemistry, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - Shawn M. Gomez
- Depts of Biomedical Engineering, Computer Science and Pharmacology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
| | - James E. Bear
- Dept of Cell & Developmental Biology, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine; Chapel Hill, NC 27599 USA
- Howard Hughes Medical Institute
| |
Collapse
|
37
|
Mackey-Cushman SL, Gao J, Holmes DA, Nunoya JI, Wang R, Unutmaz D, Su L. FoxP3 interacts with linker histone H1.5 to modulate gene expression and program Treg cell activity. Genes Immun 2011; 12:559-67. [PMID: 21654845 PMCID: PMC4329728 DOI: 10.1038/gene.2011.31] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 03/04/2011] [Accepted: 03/09/2011] [Indexed: 01/10/2023]
Abstract
The forkhead box transcription factor FoxP3 controls the development and function of CD4+CD25+ regulatory T (Treg) cell. FoxP3 modulates gene expression in Treg cells by multiple epigenetic mechanisms that are not clearly defined. We identified FoxP3-interacting proteins in human T cells by co-immunoprecipitation/MS. We discovered that FoxP3 interacted with linker histone H1.5 via the leucine zipper (LZ) domain. Two independent IPEX patient-derived single residue mutations in the LZ of FoxP3 both abrogated its interaction with H1.5. Functionally, FoxP3 and H1.5 cooperatively repressed interleukin-2 (IL-2) expression in human T cells; and silencing of H1.5 expression inhibited the ability of FoxP3 to suppress IL-2 expression. We show that FoxP3 specifically enhanced H1.5 association at the IL-2 promoter, but reduce its association at the CTLA4 promoter, correlated with higher or lower histone acetylation of the respective promoters. Finally, silencing of H1.5 expression in human Treg cells impaired the Treg function to suppress target T cells. We conclude that FoxP3 interacts with H1.5 to alter its binding to target genes to modulate their expression and to program Treg function.
Collapse
Affiliation(s)
| | - Jianmei Gao
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill Chapel Hill, NC 27599
| | - Derek A. Holmes
- Department of Microbiology and Immunology University of North Carolina, Chapel Hill Chapel Hill, NC 27599
| | - Jun-ichi Nunoya
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill Chapel Hill, NC 27599
| | - Rui Wang
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Derya Unutmaz
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Lishan Su
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill Chapel Hill, NC 27599
- Department of Microbiology and Immunology University of North Carolina, Chapel Hill Chapel Hill, NC 27599
| |
Collapse
|
38
|
Regulation of IL-2 gene expression by Siva and FOXP3 in human T cells. BMC Immunol 2011; 12:54. [PMID: 21955384 PMCID: PMC3208582 DOI: 10.1186/1471-2172-12-54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/28/2011] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Severe autoinflammatory diseases are associated with mutations in the Foxp3 locus in both mice and humans. Foxp3 is required for the development, function, and maintenance of regulatory T cells (Tregs), a subset of CD4 cells that suppress T cell activation and inflammatory processes. Siva is a pro-apoptotic gene that is expressed across a range of tissues, including CD4 T cells. Siva interacts with three tumor necrosis factor receptor (TNFR) family members that are constitutively expressed on Treg cells: CD27, GITR, and OX40. RESULTS Here we report a biophysical interaction between FOXP3 and Siva. We mapped the interaction domains to Siva's C-terminus and to a central region of FOXP3. We showed that Siva repressed IL-2 induction by suppressing IL-2 promoter activity during T cell activation. Siva-1's repressive effect on IL-2 gene expression appears to be mediated by inhibition of NFkappaB, whereas FOXP3 repressed both NFkappaB and NFAT activity. CONCLUSIONS In summary, our data suggest that both FOXP3 and Siva function as negative regulators of IL-2 gene expression in Treg cells, via suppression of NFAT by FOXP3 and of NFkappaB by both FOXP3 and Siva. Our work contributes evidence for Siva's role as a T cell signalling mediator in addition to its known pro-apoptotic function. Though further investigations are needed, evidence for the biophysical interaction between FOXP3 and Siva invites the possibility that Siva may be important for proper Treg cell function.
Collapse
|
39
|
Actin capping protein is required for dendritic spine development and synapse formation. J Neurosci 2011; 31:10228-33. [PMID: 21752999 DOI: 10.1523/jneurosci.0115-11.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dendritic spines serve as the postsynaptic platform for most excitatory synapses in the mammalian brain, and their shape and size are tightly correlated with synaptic strength. The actin cytoskeleton plays a crucial role in the spine structure and its modifications during synapse development and plasticity, but the underlying regulatory mechanisms remain to be elucidated. Here, we report that actin capping protein (CP), a regulator of actin filament growth, plays an essential role for spine development and synapse formation. We found that CP expression in rat hippocampus is elevated at and after the stage of substantial synapse formation. CP knockdown in hippocampal cultures resulted in a marked decline in spine density accompanied by increased filopodia-like protrusions. Moreover, the spines of CP knockdown neurons exhibited an altered morphology, highlighted by multiple thin filopodia-like protrusions emerging from the spine head. Finally, the number of functional synapses was reduced by CP knockdown as evidenced by a reduction in the density of paired presynaptic and postsynaptic markers and in the frequency of miniature EPSCs. These findings indicate that capping of actin filaments by CP represents an essential step for the remodeling of the actin architecture underlying spine morphogenesis and synaptic formation during development.
Collapse
|
40
|
N-WASP regulates the epithelial junctional actin cytoskeleton through a non-canonical post-nucleation pathway. Nat Cell Biol 2011; 13:934-43. [DOI: 10.1038/ncb2290] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 06/03/2011] [Indexed: 12/20/2022]
|
41
|
Multicomponent analysis of junctional movements regulated by myosin II isoforms at the epithelial zonula adherens. PLoS One 2011; 6:e22458. [PMID: 21799860 PMCID: PMC3142163 DOI: 10.1371/journal.pone.0022458] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 06/27/2011] [Indexed: 11/26/2022] Open
Abstract
The zonula adherens (ZA) of epithelial cells is a site of cell-cell adhesion where cellular forces are exerted and resisted. Increasing evidence indicates that E-cadherin adhesion molecules at the ZA serve to sense force applied on the junctions and coordinate cytoskeletal responses to those forces. Efforts to understand the role that cadherins play in mechanotransduction have been limited by the lack of assays to measure the impact of forces on the ZA. In this study we used 4D imaging of GFP-tagged E-cadherin to analyse the movement of the ZA. Junctions in confluent epithelial monolayers displayed prominent movements oriented orthogonal (perpendicular) to the ZA itself. Two components were identified in these movements: a relatively slow unidirectional (translational) component that could be readily fitted by least-squares regression analysis, upon which were superimposed more rapid oscillatory movements. Myosin IIB was a dominant factor responsible for driving the unilateral translational movements. In contrast, frequency spectrum analysis revealed that depletion of Myosin IIA increased the power of the oscillatory movements. This implies that Myosin IIA may serve to dampen oscillatory movements of the ZA. This extends our recent analysis of Myosin II at the ZA to demonstrate that Myosin IIA and Myosin IIB make distinct contributions to junctional movement at the ZA.
Collapse
|
42
|
Kovacs EM, Verma S, Thomas SG, Yap AS. Tuba and N-WASP function cooperatively to position the central lumen during epithelial cyst morphogenesis. Cell Adh Migr 2011; 5:344-50. [PMID: 21677511 DOI: 10.4161/cam.5.4.16717] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The process of epithelial lumenogenesis requires coordination of a network of signaling machinery communicated to each cell through subsequent cell divisions. Formation of a single hollow lumen has previously been shown to require Tuba, a Cdc42 GEF, for Cdc42 activation and correct spindle orientation. Using a Caco-2 model of lumenogenesis, we show that knockdown (KD) of the actin regulator N-WASP, causes a multilumen phenotype similar to Tuba KD. Defects in lumenogenesis in Tuba KD and N-WASP KD cells are observed at the two cell stage with inappropriate marking of the pre-apical patch (PAP) - the precursor to lumen formation. Strikingly, both Tuba and N-WASP depend on each other for localization to the PAP. We conclude that N-WASP functions cooperatively with Tuba to facilitate lumenogenesis and this requires the polyproline region of N-WASP.
Collapse
Affiliation(s)
- Eva M Kovacs
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland-St. Lucia, QLD, Australia
| | | | | | | |
Collapse
|
43
|
Takemoto K, Matsuda T, McDougall M, Klaubert DH, Hasegawa A, Los GV, Wood KV, Miyawaki A, Nagai T. Chromophore-assisted light inactivation of HaloTag fusion proteins labeled with eosin in living cells. ACS Chem Biol 2011; 6:401-6. [PMID: 21226520 DOI: 10.1021/cb100431e] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chromophore-assisted light inactivation (CALI) is a potentially powerful tool for the acute disruption of a target protein inside living cells with high spatiotemporal resolution. This technology, however, has not been widely utilized, mainly because of the lack of an efficient chromophore as the photosensitizing agent for singlet oxygen ((1)O(2)) generation and the difficulty of covalently labeling the target protein with the chromophore. Here we choose eosin as the photosensitizing chromophore showing 11-fold more production of ((1)O(2)) than fluorescein and about 5-fold efficiency in CALI of β-galactosidase by using an eosin-labeled anti-β-galactosidase antibody compared with the fluorescein-labeled one. To covalently label target protein with eosin, we synthesize a membrane-permeable eosin ligand for HaloTag technology, demonstrating easy labeling and efficient inactivation of HaloTag-fused PKC-γ and aurora B in living cells. These antibody- and HaloTag-based CALI techniques using eosin promise effective biomolecule inactivation that is applicable to many cell biological assays in living cells.
Collapse
Affiliation(s)
- Kiwamu Takemoto
- Laboratory for Nanosystems Physiology, Research Institute for Electronic Sciences, Hokkaido University, Kita20, Nishi10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Tomoki Matsuda
- Laboratory for Nanosystems Physiology, Research Institute for Electronic Sciences, Hokkaido University, Kita20, Nishi10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Mark McDougall
- Promega BioSciences, 277 Granada Drive, San Luis Obispo, California 93401, United States
| | - Dieter H. Klaubert
- Promega BioSciences, 277 Granada Drive, San Luis Obispo, California 93401, United States
| | - Akira Hasegawa
- Promega KK, Matsumoto Building, 14-15 Nihonbashi, Odemacho, Chuo-Ku, Tokyo 103-0011, Japan
| | - Georgyi V. Los
- Promega Corporation, 2800 Woods Hollow Road, Madison, Wisconsin 53711, United States
| | - Keith V. Wood
- Promega Corporation, 2800 Woods Hollow Road, Madison, Wisconsin 53711, United States
| | - Atsushi Miyawaki
- Laboratory for Cell Function and Dynamics, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takeharu Nagai
- Laboratory for Nanosystems Physiology, Research Institute for Electronic Sciences, Hokkaido University, Kita20, Nishi10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
- Precursory Research for Embryonic Science, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
| |
Collapse
|
44
|
Vegh RB, Solntsev KM, Kuimova MK, Cho S, Liang Y, Loo BLW, Tolbert LM, Bommarius AS. Reactive oxygen species in photochemistry of the red fluorescent protein "Killer Red". Chem Commun (Camb) 2011; 47:4887-9. [PMID: 21359336 DOI: 10.1039/c0cc05713d] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The fluorescent protein aptly named "Killer Red" (KRed) is capable of killing transfected cells and inactivating fused proteins upon exposure to visible light in the presence of oxygen. We have investigated the source of the bioactive species through a variety of photophysical and photochemical techniques. Our results indicate a Type I (electron transfer mediated) photosensitizing mechanism.
Collapse
Affiliation(s)
- Russell B Vegh
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Morton RA, Luo G, Davis MI, Hales TG, Lovinger DM. Fluorophore assisted light inactivation (FALI) of recombinant 5-HT₃A receptor constitutive internalization and function. Mol Cell Neurosci 2011; 47:79-92. [PMID: 21338684 DOI: 10.1016/j.mcn.2011.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 02/03/2011] [Accepted: 02/14/2011] [Indexed: 01/06/2023] Open
Abstract
Fluorescent proteins and molecules are now widely used to tag and visualize proteins resulting in an improved understanding of protein trafficking, localization, and function. In addition, fluorescent tags have also been used to inactivate protein function in a spatially and temporally-defined manner, using a technique known as fluorophore-assisted light inactivation (FALI) or chromophore-assisted light inactivation (CALI). In this study we tagged the serotonin₃ A subunit with the α-bungarotoxin binding sequence (BBS) and subsequently labeled 5-HT₃A/BBS receptors with fluorescently conjugated α-bungarotoxin in live cells. We show that 5-HT₃A/BBS receptors are constitutively internalized in the absence of an agonist and internalization as well as receptor function are inhibited by fluorescence. The fluorescence-induced disruption of function and internalization was reduced with oxygen radical scavengers suggesting the involvement of reactive oxygen species, implicating the FALI process. Furthermore, these data suggest that intense illumination during live-cell microscopy may result in inadvertent FALI and inhibition of protein trafficking.
Collapse
Affiliation(s)
- Russell A Morton
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852, USA
| | | | | | | | | |
Collapse
|
46
|
Stabilizing role of glutamic acid 222 in the structure of Enhanced Green Fluorescent Protein. J Struct Biol 2011; 174:385-90. [PMID: 21335090 DOI: 10.1016/j.jsb.2011.02.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 01/28/2011] [Accepted: 02/10/2011] [Indexed: 11/23/2022]
Abstract
Enhanced Green Fluorescent Protein (EGFP) is a variant of wild-type Green Fluorescent Protein from the jellyfish Aequorea victoria, whose mutations S65T and F64L increase brightness and folding efficiency. EGFP is extensively used in cell biology and biochemistry as a colocalization or expression reporter. Surprisingly, the structure of this very popular protein has not been determined yet. We report here its crystallographic structure at 1.5Å resolution which shows significant differences in the vicinity of residue 64 and of the chromophore. In particular, two conformations are observed for the key residue glutamic acid 222, in apparent contradiction with the single fluorescence lifetime of the protein. We then show that X-ray induced decarboxylation of Glu222 during diffraction data collection results in the disruption of a hydrogen-bond network near the chromophore. Using single-crystal microspectrophotometry, we demonstrate that this correlates with a significant loss of the fluorescence properties. We thus propose a mechanism of bleaching of the protein at low temperature. Taken together, these two sets of results highlight the stabilizing role of Glu222 to the chromophore cavity of EGFP.
Collapse
|
47
|
Ragàs X, Cooper LP, White JH, Nonell S, Flors C. Quantification of Photosensitized Singlet Oxygen Production by a Fluorescent Protein. Chemphyschem 2010; 12:161-5. [DOI: 10.1002/cphc.201000919] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Indexed: 12/12/2022]
|
48
|
Kapustina M, Vitriol E, Elston TC, Loew LM, Jacobson K. Modeling capping protein FRAP and CALI experiments reveals in vivo regulation of actin dynamics. Cytoskeleton (Hoboken) 2010; 67:519-34. [PMID: 20623665 DOI: 10.1002/cm.20463] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To gain insights on cellular mechanisms regulating actin polymerization, we used the Virtual Cell to model fluorescence recovery after photobleaching (FRAP) and chromophore-assisted laser inactivation (CALI) experiments on EGFP-capping protein (EGFP-CP). Modeling the FRAP kinetics demonstrated that the in vivo rate for the dissociation of CP from actin filaments is much faster (approximately 0.1 s(-1)) than that measured in vitro (0.01-0.0004 s(-1)). The CALI simulation revealed that in order to induce sustainable changes in cell morphology after CP inactivation, the cells should exhibit anticapping ability. We included the VASP protein as the anticapping agent in the modeling scheme. The model predicts that VASP affinity for barbed ends has a cooperative dependence on the concentration of VASP-barbed end complexes. This dependence produces a positive feedback that stabilizes the complexes and allows sustained growth at clustered filament tips. We analyzed the range of laser intensities that are sufficient to induce changes in cell morphology. This analysis demonstrates that FRAP experiments with EGFP-CP can be performed safely without changes in cell morphology, because, the intensity of the photobleaching beam is not high enough to produce the critical concentration of free barbed ends that will induce filament growth before diffusional replacement of EGFP-CP occurs.
Collapse
Affiliation(s)
- Maryna Kapustina
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090, USA
| | | | | | | | | |
Collapse
|
49
|
Smutny M, Cox HL, Leerberg JM, Kovacs EM, Conti MA, Ferguson C, Hamilton NA, Parton RG, Adelstein RS, Yap AS. Myosin II isoforms identify distinct functional modules that support integrity of the epithelial zonula adherens. Nat Cell Biol 2010; 12:696-702. [PMID: 20543839 DOI: 10.1038/ncb2072] [Citation(s) in RCA: 260] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 05/18/2010] [Indexed: 12/15/2022]
Abstract
Classic cadherin receptors cooperate with regulators of the actin cytoskeleton to control tissue organization in health and disease. At the apical junctions of epithelial cells, the cadherin ring of the zonula adherens (ZA) couples with a contiguous ring of actin filaments to support morphogenetic processes such as tissue integration and cellular morphology. However, the molecular mechanisms that coordinate adhesion and cytoskeleton at these junctions are poorly understood. Previously we identified non-muscle myosin II as a target of Rho signalling that supports cadherin junctions in mammalian epithelial cells. Myosin II has various cellular functions, which are increasingly attributable to the specific biophysical properties and regulation of its different isoforms. Here we report that myosin II isoforms have distinct and necessary roles at cadherin junctions. Although two of the three mammalian myosin II isoforms are found at the ZA, their localization is regulated by different upstream signalling pathways. Junctional localization of myosin IIA required E-cadherin adhesion, Rho/ROCK and myosin light-chain kinase, whereas junctional myosin IIB depended on Rap1. Further, these myosin II isoforms support E-cadherin junction integrity by different mechanisms. Myosin IIA RNA-mediated interference (RNAi) selectively perturbed the accumulation of E-cadherin in the apical ZA, decreased cadherin homophilic adhesion and disrupted cadherin clustering. In contrast, myosin IIB RNAi decreased filament content, altered dynamics, and increased the lateral movement of the perijunctional actin ring. Myosin IIA and IIB therefore identify two distinct functional modules, with different upstream signals that control junctional localization, and distinct functional effects. We propose that these two isoform-based modules cooperate to coordinate adhesion receptor and F-actin organization to form apical cadherin junctions.
Collapse
Affiliation(s)
- Michael Smutny
- Institute for Molecular Bioscience, Division of Molecular Cell Biology, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Duan X, Liu L, Feng X, Wang S. Assemblies of conjugated polyelectrolytes with proteins for controlled protein photoinactivation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:1602-1606. [PMID: 20496388 DOI: 10.1002/adma.200903716] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Xinrui Duan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P R China
| | | | | | | |
Collapse
|