1
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Steffen CL, Manoharan GB, Pavic K, Yeste-Vázquez A, Knuuttila M, Arora N, Zhou Y, Härmä H, Gaigneaux A, Grossmann TN, Abankwa DK. Identification of an H-Ras nanocluster disrupting peptide. Commun Biol 2024; 7:837. [PMID: 38982284 PMCID: PMC11233548 DOI: 10.1038/s42003-024-06523-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 06/28/2024] [Indexed: 07/11/2024] Open
Abstract
Hyperactive Ras signalling is found in most cancers. Ras proteins are only active in membrane nanoclusters, which are therefore potential drug targets. We previously showed that the nanocluster scaffold galectin-1 (Gal1) enhances H-Ras nanoclustering via direct interaction with the Ras binding domain (RBD) of Raf. Here, we establish that the B-Raf preference of Gal1 emerges from the divergence of the Raf RBDs at their proposed Gal1-binding interface. We then identify the L5UR peptide, which disrupts this interaction by binding with low micromolar affinity to the B- and C-Raf-RBDs. Its 23-mer core fragment is sufficient to interfere with H-Ras nanoclustering, modulate Ras-signalling and moderately reduce cell viability. These latter two phenotypic effects may also emerge from the ability of L5UR to broadly engage with several RBD- and RA-domain containing Ras interactors. The L5UR-peptide core fragment is a starting point for the development of more specific reagents against Ras-nanoclustering and -interactors.
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Affiliation(s)
- Candy Laura Steffen
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg
| | - Ganesh Babu Manoharan
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg
| | - Karolina Pavic
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg
| | - Alejandro Yeste-Vázquez
- Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam, Amsterdam, The Netherlands
- Amsterdam Institute of Molecular and Life Sciences (AIMMS), VU University Amsterdam, Amsterdam, The Netherlands
| | - Matias Knuuttila
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Neha Arora
- Department of Integrative Biology and Pharmacology, McGovern Medical School, UT Health, Houston, TX, 77030, USA
| | - Yong Zhou
- Department of Integrative Biology and Pharmacology, McGovern Medical School, UT Health, Houston, TX, 77030, USA
| | - Harri Härmä
- Chemistry of Drug Development, Department of Chemistry, University of Turku, 20500, Turku, Finland
| | - Anthoula Gaigneaux
- Bioinformatics Core, Department of Life Sciences and Medicine, University of Luxembourg, 4367, Esch-sur-Alzette, Luxembourg
| | - Tom N Grossmann
- Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam, Amsterdam, The Netherlands
- Amsterdam Institute of Molecular and Life Sciences (AIMMS), VU University Amsterdam, Amsterdam, The Netherlands
| | - Daniel Kwaku Abankwa
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg.
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520, Turku, Finland.
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2
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Kaya P, Schaffner-Reckinger E, Manoharan GB, Vukic V, Kiriazis A, Ledda M, Burgos Renedo M, Pavic K, Gaigneaux A, Glaab E, Abankwa DK. An Improved PDE6D Inhibitor Combines with Sildenafil To Inhibit KRAS Mutant Cancer Cell Growth. J Med Chem 2024; 67:8569-8584. [PMID: 38758695 PMCID: PMC11181323 DOI: 10.1021/acs.jmedchem.3c02129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 04/09/2024] [Accepted: 04/12/2024] [Indexed: 05/19/2024]
Abstract
The trafficking chaperone PDE6D (or PDEδ) was proposed as a surrogate target for K-Ras, leading to the development of a series of inhibitors that block its prenyl binding pocket. These inhibitors suffered from low solubility and suspected off-target effects, preventing their clinical development. Here, we developed a highly soluble, low nanomolar PDE6D inhibitor (PDE6Di), Deltaflexin3, which has the lowest off-target activity as compared to three prominent reference compounds. Deltaflexin3 reduces Ras signaling and selectively decreases the growth of KRAS mutant and PDE6D-dependent cancer cells. We further show that PKG2-mediated phosphorylation of Ser181 lowers K-Ras binding to PDE6D. Thus, Deltaflexin3 combines with the approved PKG2 activator Sildenafil to more potently inhibit PDE6D/K-Ras binding, cancer cell proliferation, and microtumor growth. As observed previously, inhibition of Ras trafficking, signaling, and cancer cell proliferation remained overall modest. Our results suggest reevaluating PDE6D as a K-Ras surrogate target in cancer.
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Affiliation(s)
- Pelin Kaya
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Elisabeth Schaffner-Reckinger
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Ganesh babu Manoharan
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Vladimir Vukic
- Faculty
of Technology, University of Novi Sad, 21000 Novi Sad, Serbia
| | - Alexandros Kiriazis
- Turku
Bioscience Centre, University of Turku and
Åbo Akademi University, 20520 Turku, Finland
| | - Mirko Ledda
- Luxembourg
Center for Systems Biomedicine, University
of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Maria Burgos Renedo
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Karolina Pavic
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Anthoula Gaigneaux
- Bioinformatics
Core, Department of Life Sciences and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Enrico Glaab
- Luxembourg
Center for Systems Biomedicine, University
of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
| | - Daniel Kwaku Abankwa
- Cancer
Cell Biology and Drug Discovery Group, Department of Life Sciences
and Medicine, University of Luxembourg, 4365 Esch-sur-Alzette, Luxembourg
- Turku
Bioscience Centre, University of Turku and
Åbo Akademi University, 20520 Turku, Finland
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3
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Vu CQ, Arai S. Quantitative Imaging of Genetically Encoded Fluorescence Lifetime Biosensors. BIOSENSORS 2023; 13:939. [PMID: 37887132 PMCID: PMC10605767 DOI: 10.3390/bios13100939] [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] [Received: 09/05/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023]
Abstract
Genetically encoded fluorescence lifetime biosensors have emerged as powerful tools for quantitative imaging, enabling precise measurement of cellular metabolites, molecular interactions, and dynamic cellular processes. This review provides an overview of the principles, applications, and advancements in quantitative imaging with genetically encoded fluorescence lifetime biosensors using fluorescence lifetime imaging microscopy (go-FLIM). We highlighted the distinct advantages of fluorescence lifetime-based measurements, including independence from expression levels, excitation power, and focus drift, resulting in robust and reliable measurements compared to intensity-based approaches. Specifically, we focus on two types of go-FLIM, namely Förster resonance energy transfer (FRET)-FLIM and single-fluorescent protein (FP)-based FLIM biosensors, and discuss their unique characteristics and benefits. This review serves as a valuable resource for researchers interested in leveraging fluorescence lifetime imaging to study molecular interactions and cellular metabolism with high precision and accuracy.
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Affiliation(s)
- Cong Quang Vu
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Satoshi Arai
- WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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4
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Babu Manoharan G, Guzmán C, Najumudeen AK, Abankwa D. Detection of Ras nanoclustering-dependent homo-FRET using fluorescence anisotropy measurements. Eur J Cell Biol 2023; 102:151314. [PMID: 37058825 DOI: 10.1016/j.ejcb.2023.151314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 03/10/2023] [Accepted: 04/10/2023] [Indexed: 04/16/2023] Open
Abstract
The small GTPase Ras is frequently mutated in cancer and a driver of tumorigenesis. The recent years have shown great progress in drug-targeting Ras and understanding how it operates on the plasma membrane. We now know that Ras is non-randomly organized into proteo-lipid complexes on the membrane, called nanoclusters. Nanoclusters contain only a few Ras proteins and are necessary for the recruitment of downstream effectors, such as Raf. If tagged with fluorescent proteins, the dense packing of Ras in nanoclusters can be analyzed by Förster/ fluorescence resonance energy transfer (FRET). Loss of FRET can therefore report on decreased nanoclustering and any process upstream of it, such as Ras lipid modifications and correct trafficking. Thus, cellular FRET screens employing Ras-derived fluorescence biosensors are potentially powerful tools to discover chemical or genetic modulators of functional Ras membrane organization. Here we implement fluorescence anisotropy-based homo-FRET measurements of Ras-derived constructs labelled with only one fluorescent protein on a confocal microscope and a fluorescence plate reader. We show that homo-FRET of both H-Ras- and K-Ras-derived constructs can sensitively report on Ras-lipidation and -trafficking inhibitors, as well as on genetic perturbations of proteins regulating membrane anchorage. By exploiting the switch I/II-binding Ras-dimerizing compound BI-2852, this assay is also suitable to report on the engagement of the K-Ras switch II pocket by small molecules such as AMG 510. Given that homo-FRET only requires one fluorescent protein tagged Ras construct, this approach has significant advantages to create Ras-nanoclustering FRET-biosensor reporter cell lines, as compared to the more common hetero-FRET approaches.
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Affiliation(s)
- Ganesh Babu Manoharan
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Camilo Guzmán
- Euro-BioImaging ERIC, Statutory Seat, Turku, Finland
| | - Arafath Kaja Najumudeen
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Daniel Abankwa
- Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
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5
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Pavic K, Chippalkatti R, Abankwa D. Drug targeting opportunities en route to Ras nanoclusters. Adv Cancer Res 2022; 153:63-99. [PMID: 35101236 DOI: 10.1016/bs.acr.2021.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Disruption of the native membrane organization of Ras by the farnesyltransferase inhibitor tipifarnib in the late 1990s constituted the first indirect approach to drug target Ras. Since then, our understanding of how dynamically Ras shuttles between subcellular locations has changed significantly. Ras proteins have to arrive at the plasma membrane for efficient MAPK-signal propagation. On the plasma membrane Ras proteins are organized into isoform specific proteo-lipid assemblies called nanocluster. Recent evidence suggests that Ras nanocluster have a specific lipid composition, which supports the recruitment of effectors such as Raf. Conversely, effectors possess lipid-recognition motifs, which appear to serve as co-incidence detectors for the lipid domain of a given Ras isoform. Evidence suggests that dimeric Raf proteins then co-assemble dimeric Ras in an immobile complex, thus forming the minimal unit of an active nanocluster. Here we review established and novel trafficking chaperones and trafficking factors of Ras, along with the set of lipid and protein modulators of Ras nanoclustering. We highlight drug targeting approaches and opportunities against these determinants of functional Ras membrane organization. Finally, we reflect on implications for Ras signaling in polarized cells, such as epithelia, which are a common origin of tumorigenesis.
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Affiliation(s)
- Karolina Pavic
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Rohan Chippalkatti
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Daniel Abankwa
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
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6
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Parkkola H, Siddiqui FA, Oetken-Lindholm C, Abankwa D. FLIM-FRET Analysis of Ras Nanoclustering and Membrane-Anchorage. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2262:233-250. [PMID: 33977480 DOI: 10.1007/978-1-0716-1190-6_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
On the plasma membrane, Ras is organized into laterally segregated proteo-lipid complexes called nanoclusters. The extent of Ras nanoclustering correlates with its signaling output, positioning nanocluster as dynamic signaling gain modulators. Recent evidence suggests that stacked dimers of Ras and Raf are elemental units at least of one type of Ras nanocluster. However, it is still incompletely understood, in which physiological contexts nanoclustering is regulated and which constituents are parts of nanocluster. Nonetheless, disruption of nanoclustering faithfully diminishes Ras activity in cells, suggesting Ras nanocluster as potential drug targets.While there are several methods available to study Ras nanocluster , fluorescence or Förster resonance energy transfer (FRET ) between fluorescently labeled, nanoclustered Ras proteins is a relatively simple readout. FRET measurements using fluorescence lifetime imaging microscopy (FLIM ) have proven to be robust and sensitive to determine Ras nanoclustering changes. Loss of FRET that emerges due to nanoclustering reports on all processes upstream of Ras nanoclustering, i.e., also on proper trafficking or lipid modification of Ras. Here we report our standard FLIM-FRET protocol to measure nanoclustering-dependent FRET of Ras in mammalian cells. Importantly, nanoclustering-dependent FRET is one of the few methods that can detect differences between the Ras isoforms.
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Affiliation(s)
- Hanna Parkkola
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
| | - Farid Ahmad Siddiqui
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
| | | | - Daniel Abankwa
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland.
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
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7
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Elaiophylin Is a Potent Hsp90/ Cdc37 Protein Interface Inhibitor with K-Ras Nanocluster Selectivity. Biomolecules 2021; 11:biom11060836. [PMID: 34199986 PMCID: PMC8229862 DOI: 10.3390/biom11060836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/27/2021] [Accepted: 06/01/2021] [Indexed: 12/19/2022] Open
Abstract
The natural product elaiophylin is a macrodiolide with a broad range of biological activities. However, no direct target of elaiophylin in eukaryotes has been described so far, which hinders a systematic explanation of its astonishing activity range. We recently showed that the related conglobatin A, a protein–protein interface inhibitor of the interaction between the N-terminus of Hsp90 and its cochaperone Cdc37, blocks cancer stem cell properties by selectively inhibiting K-Ras4B but not H-Ras. Here, we elaborated that elaiophylin likewise disrupts the Hsp90/ Cdc37 interaction, without affecting the ATP-pocket of Hsp90. Similarly to conglobatin A, elaiophylin decreased expression levels of the Hsp90 client HIF1α, a transcription factor with various downstream targets, including galectin-3. Galectin-3 is a nanocluster scaffold of K-Ras, which explains the K-Ras selectivity of Hsp90 inhibitors. In agreement with this K-Ras targeting and the potent effect on other Hsp90 clients, we observed with elaiophylin treatment a submicromolar IC50 for MDA-MB-231 and MIA-PaCa-2 3D spheroid formation. Finally, a strong inhibition of MDA-MB-231 cells grown in the chorioallantoic membrane (CAM) microtumor model was determined. These results suggest that several other macrodiolides may have the Hsp90/ Cdc37 interface as a target site.
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8
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Bitton A, Sambrano J, Valentino S, Houston JP. A Review of New High-Throughput Methods Designed for Fluorescence Lifetime Sensing From Cells and Tissues. FRONTIERS IN PHYSICS 2021; 9:648553. [PMID: 34007839 PMCID: PMC8127321 DOI: 10.3389/fphy.2021.648553] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Though much of the interest in fluorescence in the past has been on measuring spectral qualities such as wavelength and intensity, there are two other highly useful intrinsic properties of fluorescence: lifetime (or decay) and anisotropy (or polarization). Each has its own set of unique advantages, limitations, and challenges in detection when it comes to use in biological studies. This review will focus on the property of fluorescence lifetime, providing a brief background on instrumentation and theory, and examine the recent advancements and applications of measuring lifetime in the fields of high-throughput fluorescence lifetime imaging microscopy (HT-FLIM) and time-resolved flow cytometry (TRFC). In addition, the crossover of these two methods and their outlooks will be discussed.
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Affiliation(s)
- Aric Bitton
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM, United States
| | - Jesus Sambrano
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM, United States
| | - Samantha Valentino
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM, United States
| | - Jessica P. Houston
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM, United States
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9
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Siddiqui FA, Parkkola H, Vukic V, Oetken-Lindholm C, Jaiswal A, Kiriazis A, Pavic K, Aittokallio T, Salminen TA, Abankwa D. Novel Small Molecule Hsp90/Cdc37 Interface Inhibitors Indirectly Target K-Ras-Signaling. Cancers (Basel) 2021; 13:927. [PMID: 33672199 PMCID: PMC7927014 DOI: 10.3390/cancers13040927] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/12/2021] [Accepted: 02/17/2021] [Indexed: 12/23/2022] Open
Abstract
The ATP-competitive inhibitors of Hsp90 have been tested predominantly in kinase addicted cancers; however, they have had limited success. A mechanistic connection between Hsp90 and oncogenic K-Ras is not known. Here, we show that K-Ras selectivity is enabled by the loss of the K-Ras membrane nanocluster modulator galectin-3 downstream of the Hsp90 client HIF-1α. This mechanism suggests a higher drug sensitivity in the context of KRAS mutant, HIF-1α-high and/or Gal3-high cancer cells, such as those found, in particular, in pancreatic adenocarcinoma. The low toxicity of conglobatin further indicates a beneficial on-target toxicity profile for Hsp90/Cdc37 interface inhibitors. We therefore computationally screened >7 M compounds, and identified four novel small molecules with activities of 4 μM-44 μM in vitro. All of the compounds were K-Ras selective, and potently decreased the Hsp90 client protein levels without inducing the heat shock response. Moreover, they all inhibited the 2D proliferation of breast, pancreatic, and lung cancer cell lines. The most active compounds from each scaffold, furthermore, significantly blocked 3D spheroids and the growth of K-Ras-dependent microtumors. We foresee new opportunities for improved Hsp90/Cdc37 interface inhibitors in cancer and other aging-associated diseases.
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Affiliation(s)
- Farid Ahmad Siddiqui
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
| | - Hanna Parkkola
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
| | - Vladimir Vukic
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
- Faculty of Technology, University of Novi Sad, 21000 Novi Sad, Serbia
| | - Christina Oetken-Lindholm
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
| | - Alok Jaiswal
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, 00014 Helsinki, Finland; (A.J.); (T.A.)
| | - Alexandros Kiriazis
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
| | - Karolina Pavic
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg;
| | - Tero Aittokallio
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, 00014 Helsinki, Finland; (A.J.); (T.A.)
- Department of Cancer Genetics, Institute for Cancer Research, Oslo University Hospital, N-0310 Oslo, Norway
- Centre for Biostatistics and Epidemiology (OCBE), Faculty of Medicine, University of Oslo, N-0372 Oslo, Norway
| | - Tiina A. Salminen
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland;
| | - Daniel Abankwa
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland; (F.A.S.); (H.P.); (V.V.); (C.O.-L.); (A.K.)
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg;
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10
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Ahearn IM, Court HR, Siddiqui F, Abankwa D, Philips MR. NRAS is unique among RAS proteins in requiring ICMT for trafficking to the plasma membrane. Life Sci Alliance 2021; 4:4/5/e202000972. [PMID: 33579760 PMCID: PMC7893820 DOI: 10.26508/lsa.202000972] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/17/2022] Open
Abstract
Among the RAS isoforms, NRAS uniquely requires carboxyl methylation by ICMT for delivery to the plasma membrane because of having only a single palmitoylation as a second targeting signal. Isoprenylcysteine carboxyl methyltransferase (ICMT) is the third of three enzymes that sequentially modify the C-terminus of CaaX proteins, including RAS. Although all four RAS proteins are substrates for ICMT, each traffics to membranes differently by virtue of their hypervariable regions that are differentially palmitoylated. We found that among RAS proteins, NRAS was unique in requiring ICMT for delivery to the PM, a consequence of having only a single palmitoylation site as its secondary affinity module. Although not absolutely required for palmitoylation, acylation was diminished in the absence of ICMT. Photoactivation and FRAP of GFP-NRAS revealed increase flux at the Golgi, independent of palmitoylation, in the absence of ICMT. Association of NRAS with the prenyl-protein chaperone PDE6δ also required ICMT and promoted anterograde trafficking from the Golgi. We conclude that carboxyl methylation of NRAS is required for efficient palmitoylation, PDE6δ binding, and homeostatic flux through the Golgi, processes that direct delivery to the plasma membrane.
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Affiliation(s)
- Ian M Ahearn
- The Ronald O Perelman Department of Dermatology, New York University Grossman School of Medicine, New York, NY, USA .,The Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY, USA.,Veterans Affairs New York Harbor Healthcare System, Manhattan Campus, New York, NY, USA
| | - Helen R Court
- The Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY, USA
| | - Farid Siddiqui
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
| | - Daniel Abankwa
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland.,Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Mark R Philips
- The Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY, USA
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11
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Brodwolf R, Volz-Rakebrand P, Stellmacher J, Wolff C, Unbehauen M, Haag R, Schäfer-Korting M, Zoschke C, Alexiev U. Faster, sharper, more precise: Automated Cluster-FLIM in preclinical testing directly identifies the intracellular fate of theranostics in live cells and tissue. Theranostics 2020; 10:6322-6336. [PMID: 32483455 PMCID: PMC7255044 DOI: 10.7150/thno.42581] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/01/2020] [Indexed: 12/25/2022] Open
Abstract
Fluorescence microscopy is widely used for high content screening in 2D cell cultures and 3D models. In particular, 3D tissue models are gaining major relevance in modern drug development. Enabling direct multiparametric evaluation of complex samples, fluorescence lifetime imaging (FLIM) adds a further level to intensity imaging by the sensitivity of the fluorescence lifetime to the microenvironment. However, the use of FLIM is limited amongst others by the acquisition of sufficient photon numbers without phototoxic effects in live cells. Herein, we developed a new cluster-based analysis method to enhance insight, and significantly speed up analysis and measurement time for the accurate translation of fluorescence lifetime information into pharmacological pathways. Methods: We applied a fluorescently-labeled dendritic core-multishell nanocarrier and its cargo Bodipy as molecules of interest (MOI) to human cells and reconstructed human tissue. Following the sensitivity and specificity assessment of the fitting-free Cluster-FLIM analysis of data in silico and in vitro, we evaluated the dynamics of cellular molecule uptake and intracellular interactions. For 3D live tissue investigations, we applied multiphoton (mp) FLIM. Owing to Cluster-FLIM's statistics-based fitting-free analysis, we utilized this approach for automatization. Results: To discriminate the fluorescence lifetime signatures of 5 different fluorescence species in a single color channel, the Cluster-FLIM method requires only 170, respectively, 90 counts per pixel to obtain 95% sensitivity (hit rate) and 95% specificity (correct rejection rate). Cluster-FLIM revealed cellular interactions of MOIs, representing their spatiotemporal intracellular fate. In a setting of an automated workflow, the assessment of lysosomal trapping of the MOI revealed relevant differences between normal and tumor cells, as well as between 2D and 3D models. Conclusion: The automated Cluster-FLIM tool is fitting-free, providing images with enhanced information, contrast, and spatial resolution at short exposure times and low fluorophore concentrations. Thereby, Cluster-FLIM increases the applicability of FLIM in high content analysis of target molecules in drug development and beyond.
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12
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Sizaire F, Le Marchand G, Pécréaux J, Bouchareb O, Tramier M. Automated screening of AURKA activity based on a genetically encoded FRET biosensor using fluorescence lifetime imaging microscopy. Methods Appl Fluoresc 2020; 8:024006. [PMID: 32032967 DOI: 10.1088/2050-6120/ab73f5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Fluorescence Lifetime Imaging Microscopy (FLIM) is a robust tool to measure Förster Resonance Energy Transfer (FRET) between two fluorescent proteins, mainly when using genetically-encoded FRET biosensors. It is then possible to monitor biological processes such as kinase activity with a good spatiotemporal resolution and accuracy. Therefore, it is of interest to improve this methodology for future high content screening purposes. We here implement a time-gated FLIM microscope that can image and quantify fluorescence lifetime with a higher speed than conventional techniques such as Time-Correlated Single Photon Counting (TCSPC). We then improve our system to perform automatic screen analysis in a 96-well plate format. Moreover, we use a FRET biosensor of AURKA activity, a mitotic kinase involved in several epithelial cancers. Our results show that our system is suitable to measure FRET within our biosensor paving the way to the screening of novel compounds, potentially allowing to find new inhibitors of AURKA activity.
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Affiliation(s)
- Florian Sizaire
- Univ Rennes, CNRS, IGDR (Genetics and Development Institute of Rennes), UMR 6290, F-35000 Rennes, France
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13
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Poudel C, Mela I, Kaminski CF. High-throughput, multi-parametric, and correlative fluorescence lifetime imaging. Methods Appl Fluoresc 2020; 8:024005. [PMID: 32028271 PMCID: PMC8208541 DOI: 10.1088/2050-6120/ab7364] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 12/18/2019] [Accepted: 02/06/2020] [Indexed: 12/11/2022]
Abstract
In this review, we discuss methods and advancements in fluorescence lifetime imaging microscopy that permit measurements to be performed at faster speed and higher resolution than previously possible. We review fast single-photon timing technologies and the use of parallelized detection schemes to enable high-throughput and high content imaging applications. We appraise different technological implementations of fluorescence lifetime imaging, primarily in the time-domain. We also review combinations of fluorescence lifetime with other imaging modalities to capture multi-dimensional and correlative information from a single sample. Throughout the review, we focus on applications in biomedical research. We conclude with a critical outlook on current challenges and future opportunities in this rapidly developing field.
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Affiliation(s)
- Chetan Poudel
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology,
Philippa Fawcett Drive, University of
Cambridge, Cambridge CB3 0AS, United
Kingdom
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14
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Siddiqui F, Alam C, Rosenqvist P, Ora M, Sabt A, Manoharan GB, Bindu L, Okutachi S, Catillon M, Taylor T, Abdelhafez OM, Lönnberg H, Stephen AG, Papageorgiou AC, Virta P, Abankwa D. PDE6D Inhibitors with a New Design Principle Selectively Block K-Ras Activity. ACS OMEGA 2020; 5:832-842. [PMID: 31956834 PMCID: PMC6964506 DOI: 10.1021/acsomega.9b03639] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 12/09/2019] [Indexed: 05/12/2023]
Abstract
The trafficking chaperone PDE6D (also referred to as PDEδ) has been nominated as a surrogate target for K-Ras4B (hereafter K-Ras). Arl2-assisted unloading of K-Ras from PDE6D in the perinuclear area is significant for correct K-Ras localization and therefore activity. However, the unloading mechanism also leads to the undesired ejection of PDE6D inhibitors. To counteract ejection, others have recently optimized inhibitors for picomolar affinities; however, cell penetration generally seems to remain an issue. To increase resilience against ejection, we engineered a "chemical spring" into prenyl-binding pocket inhibitors of PDE6D. Furthermore, cell penetration was improved by attaching a cell-penetration group, allowing us to arrive at micromolar in cellulo potencies in the first generation. Our model compounds, Deltaflexin-1 and -2, selectively disrupt K-Ras, but not H-Ras membrane organization. This selectivity profile is reflected in the antiproliferative activity on colorectal and breast cancer cells, as well as the ability to block stemness traits of lung and breast cancer cells. While our current model compounds still have a low in vitro potency, we expect that our modular and simple inhibitor redesign could significantly advance the development of pharmacologically more potent compounds against PDE6D and related targets, such as UNC119 in the future.
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Affiliation(s)
- Farid
A. Siddiqui
- Turku
Bioscience Centre, University of Turku and
Åbo Akademi University, 20520 Turku, Finland
| | - Catharina Alam
- Turku
Bioscience Centre, University of Turku and
Åbo Akademi University, 20520 Turku, Finland
| | - Petja Rosenqvist
- Department
of Chemistry, University of Turku, 20014 Turku, Finland
| | - Mikko Ora
- Department
of Chemistry, University of Turku, 20014 Turku, Finland
| | - Ahmed Sabt
- Department
of Chemistry, University of Turku, 20014 Turku, Finland
- Chemistry
of Natural Compounds Department, National
Research Centre, Dokki, 12622 Giza, Egypt
| | - Ganesh babu Manoharan
- Cancer
Cell Biology and Drug Discovery Group, Life Sciences Research Unit, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg
| | - Lakshman Bindu
- NCI
RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, 21702 Frederick, Maryland, United States
| | - Sunday Okutachi
- Cancer
Cell Biology and Drug Discovery Group, Life Sciences Research Unit, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg
| | - Marie Catillon
- Cancer
Cell Biology and Drug Discovery Group, Life Sciences Research Unit, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg
| | - Troy Taylor
- NCI
RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, 21702 Frederick, Maryland, United States
| | - Omaima M. Abdelhafez
- Chemistry
of Natural Compounds Department, National
Research Centre, Dokki, 12622 Giza, Egypt
| | - Harri Lönnberg
- Department
of Chemistry, University of Turku, 20014 Turku, Finland
| | - Andrew G. Stephen
- NCI
RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, 21702 Frederick, Maryland, United States
| | | | - Pasi Virta
- Department
of Chemistry, University of Turku, 20014 Turku, Finland
| | - Daniel Abankwa
- Turku
Bioscience Centre, University of Turku and
Åbo Akademi University, 20520 Turku, Finland
- Cancer
Cell Biology and Drug Discovery Group, Life Sciences Research Unit, University of Luxembourg, 4362 Esch-sur-Alzette, Luxembourg
- E-mail:
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15
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Wang S, Chacko JV, Sagar AK, Eliceiri KW, Yuan M. Nonparametric empirical Bayesian framework for fluorescence-lifetime imaging microscopy. BIOMEDICAL OPTICS EXPRESS 2019; 10:5497-5517. [PMID: 31799027 PMCID: PMC6865096 DOI: 10.1364/boe.10.005497] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/31/2019] [Accepted: 09/29/2019] [Indexed: 05/02/2023]
Abstract
Fluorescence lifetime imaging microscopy (FLIM) is a powerful imaging tool used to study the molecular environment of flurophores. In time domain FLIM, extracting lifetime from fluorophores signals entails fitting data to a decaying exponential distribution function. However, most existing techniques for this purpose need large amounts of photons at each pixel and a long computation time, thus making it difficult to obtain reliable inference in applications requiring either short acquisition or minimal computation time. In this work, we introduce a new nonparametric empirical Bayesian framework for FLIM data analysis (NEB-FLIM), leading to both improved pixel-wise lifetime estimation and a more robust and computationally efficient integral property inference. This framework is developed based on a newly proposed hierarchical statistical model for FLIM data and adopts a novel nonparametric maximum likelihood estimator to estimate the prior distribution. To demonstrate the merit of the proposed framework, we applied it on both simulated and real biological datasets and compared it with previous classical methods on these datasets.
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Affiliation(s)
- Shulei Wang
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jenu V Chacko
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI 53706, USA
| | - Abdul K Sagar
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI 53706, USA
| | - Kevin W Eliceiri
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53706, USA
| | - Ming Yuan
- Department of Statistics, Columbia University, New York, NY 10027, USA
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16
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Nguyen TA, Puhl HL, Pham AK, Vogel SS. Auto-FPFA: An Automated Microscope for Characterizing Genetically Encoded Biosensors. Sci Rep 2018; 8:7374. [PMID: 29743504 PMCID: PMC5943267 DOI: 10.1038/s41598-018-25689-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/26/2018] [Indexed: 12/14/2022] Open
Abstract
Genetically encoded biosensors function by linking structural change in a protein construct, typically tagged with one or more fluorescent proteins, to changes in a biological parameter of interest (such as calcium concentration, pH, phosphorylation-state, etc.). Typically, the structural change triggered by alterations in the bio-parameter is monitored as a change in either fluorescent intensity, or lifetime. Potentially, other photo-physical properties of fluorophores, such as fluorescence anisotropy, molecular brightness, concentration, and lateral and/or rotational diffusion could also be used. Furthermore, while it is likely that multiple photo-physical attributes of a biosensor might be altered as a function of the bio-parameter, standard measurements monitor only a single photo-physical trait. This limits how biosensors are designed, as well as the accuracy and interpretation of biosensor measurements. Here we describe the design and construction of an automated multimodal-microscope. This system can autonomously analyze 96 samples in a micro-titer dish and for each sample simultaneously measure intensity (photon count), fluorescence lifetime, time-resolved anisotropy, molecular brightness, lateral diffusion time, and concentration. We characterize the accuracy and precision of this instrument, and then demonstrate its utility by characterizing three types of genetically encoded calcium sensors as well as a negative control.
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Affiliation(s)
- Tuan A Nguyen
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland, USA
| | - Henry L Puhl
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland, USA
| | - An K Pham
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland, USA
| | - Steven S Vogel
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland, USA.
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17
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Bassard JE, Halkier BA. How to prove the existence of metabolons? PHYTOCHEMISTRY REVIEWS : PROCEEDINGS OF THE PHYTOCHEMICAL SOCIETY OF EUROPE 2018; 17:211-227. [PMID: 29755303 PMCID: PMC5932110 DOI: 10.1007/s11101-017-9509-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 04/19/2017] [Indexed: 05/21/2023]
Abstract
Sequential enzymes in biosynthetic pathways are organized in metabolons. It is challenging to provide experimental evidence for the existence of metabolons as biosynthetic pathways are composed of highly dynamic protein-protein interactions. Many different methods are being applied, each with strengths and weaknesses. We will present and evaluate several techniques that have been applied in providing evidence for the orchestration of the biosynthetic pathways of cyanogenic glucosides and glucosinolates in metabolons. These evolutionarily related pathways have ER-localized cytochromes P450 that are proposed to function as anchoring site for assembly of the enzymes into metabolons. Additionally, we have included commonly used techniques, even though they have not been used (yet) on these two pathways. In the review, special attention will be given to less-exploited fluorescence-based methods such as FCS and FLIM. Ultimately, understanding the orchestration of biosynthetic pathways may contribute to successful engineering in heterologous hosts.
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Affiliation(s)
- Jean-Etienne Bassard
- Plant Biochemistry Laboratory, Center for Synthetic Biology, VILLUM Research Center “Plant Plasticity”, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Barbara Ann Halkier
- DynaMo Center, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Schaaf TM, Peterson KC, Grant BD, Bawaskar P, Yuen S, Li J, Muretta JM, Gillispie GD, Thomas DD. High-Throughput Spectral and Lifetime-Based FRET Screening in Living Cells to Identify Small-Molecule Effectors of SERCA. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2017; 22:262-273. [PMID: 27899691 PMCID: PMC5323330 DOI: 10.1177/1087057116680151] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A robust high-throughput screening (HTS) strategy has been developed to discover small-molecule effectors targeting the sarco/endoplasmic reticulum calcium ATPase (SERCA), based on a fluorescence microplate reader that records both the nanosecond decay waveform (lifetime mode) and the complete emission spectrum (spectral mode), with high precision and speed. This spectral unmixing plate reader (SUPR) was used to screen libraries of small molecules with a fluorescence resonance energy transfer (FRET) biosensor expressed in living cells. Ligand binding was detected by FRET associated with structural rearrangements of green fluorescent protein (GFP, donor) and red fluorescent protein (RFP, acceptor) fused to the cardiac-specific SERCA2a isoform. The results demonstrate accurate quantitation of FRET along with high precision of hit identification. Fluorescence lifetime analysis resolved SERCA's distinct structural states, providing a method to classify small-molecule chemotypes on the basis of their structural effect on the target. The spectral analysis was also applied to flag interference by fluorescent compounds. FRET hits were further evaluated for functional effects on SERCA's ATPase activity via both a coupled-enzyme assay and a FRET-based calcium sensor. Concentration-response curves indicated excellent correlation between FRET and function. These complementary spectral and lifetime FRET detection methods offer an attractive combination of precision, speed, and resolution for HTS.
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Affiliation(s)
- Tory M. Schaaf
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | | | | | - Prachi Bawaskar
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Samantha Yuen
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Ji Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Joseph M. Muretta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | | | - David D. Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
- Photonic Pharma LLC, Minneapolis, MN 55410
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19
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Schaaf TM, Peterson KC, Grant BD, Thomas DD, Gillispie GD. Spectral Unmixing Plate Reader: High-Throughput, High-Precision FRET Assays in Living Cells. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2017; 22:250-261. [PMID: 27879398 PMCID: PMC5506495 DOI: 10.1177/1087057116679637] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have developed a microplate reader that records a complete high-quality fluorescence emission spectrum on a well-by-well basis under true high-throughput screening (HTS) conditions. The read time for an entire 384-well plate is less than 3 min. This instrument is particularly well suited for assays based on fluorescence resonance energy transfer (FRET). Intramolecular protein biosensors with genetically encoded green fluorescent protein (GFP) donor and red fluorescent protein (RFP) acceptor tags at positions sensitive to structural changes were stably expressed and studied in living HEK cells. Accurate quantitation of FRET was achieved by decomposing each observed spectrum into a linear combination of four component (basis) spectra (GFP emission, RFP emission, water Raman, and cell autofluorescence). Excitation and detection are both conducted from the top, allowing for thermoelectric control of the sample temperature from below. This spectral unmixing plate reader (SUPR) delivers an unprecedented combination of speed, precision, and accuracy for studying ensemble-averaged FRET in living cells. It complements our previously reported fluorescence lifetime plate reader, which offers the feature of resolving multiple FRET populations within the ensemble. The combination of these two direct waveform-recording technologies greatly enhances the precision and information content for HTS in drug discovery.
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Affiliation(s)
- Tory M. Schaaf
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | | | | | - David D. Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
- Photonic Pharma LLC, Minneapolis, MN 55410
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20
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Chow EKH. The 2017 SLAS Technology Ten: Translating Life Sciences Innovation. SLAS Technol 2017; 22:3-6. [DOI: 10.1177/2472630316683633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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Najumudeen AK, Jaiswal A, Lectez B, Oetken-Lindholm C, Guzmán C, Siljamäki E, Posada IMD, Lacey E, Aittokallio T, Abankwa D. Cancer stem cell drugs target K-ras signaling in a stemness context. Oncogene 2016; 35:5248-5262. [PMID: 26973241 PMCID: PMC5057041 DOI: 10.1038/onc.2016.59] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 01/22/2016] [Accepted: 01/25/2016] [Indexed: 01/02/2023]
Abstract
Cancer stem cells (CSCs) are considered to be responsible for treatment relapse and have therefore become a major target in cancer research. Salinomycin is the most established CSC inhibitor. However, its primary mechanistic target is still unclear, impeding the discovery of compounds with similar anti-CSC activity. Here, we show that salinomycin very specifically interferes with the activity of K-ras4B, but not H-ras, by disrupting its nanoscale membrane organization. We found that caveolae negatively regulate the sensitivity to this drug. On the basis of this novel mechanistic insight, we defined a K-ras-associated and stem cell-derived gene expression signature that predicts the drug response of cancer cells to salinomycin. Consistent with therapy resistance of CSC, 8% of tumor samples in the TCGA-database displayed our signature and were associated with a significantly higher mortality. Using our K-ras-specific screening platform, we identified several new candidate CSC drugs. Two of these, ophiobolin A and conglobatin A, possessed a similar or higher potency than salinomycin. Finally, we established that the most potent compound, ophiobolin A, exerts its K-ras4B-specific activity through inactivation of calmodulin. Our data suggest that specific interference with the K-ras4B/calmodulin interaction selectively inhibits CSC.
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Affiliation(s)
- A K Najumudeen
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - A Jaiswal
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Helsinki, Finland
| | - B Lectez
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - C Oetken-Lindholm
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - C Guzmán
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - E Siljamäki
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - I M D Posada
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
| | - E Lacey
- Microbial Screening Technologies Pty. Ltd., Building C, Smithfield, New South Wales, Australia
| | - T Aittokallio
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Helsinki, Finland
| | - D Abankwa
- Turku Centre for Biotechnology, Åbo Akademi University, Turku, Finland
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22
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SPRED1 Interferes with K-ras but Not H-ras Membrane Anchorage and Signaling. Mol Cell Biol 2016; 36:2612-25. [PMID: 27503857 DOI: 10.1128/mcb.00191-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/03/2016] [Indexed: 12/13/2022] Open
Abstract
The Ras/mitogen-activated protein kinase (MAPK) signaling pathway is tightly controlled by negative feedback regulators, such as the tumor suppressor SPRED1. The SPRED1 gene also carries loss-of-function mutations in the RASopathy Legius syndrome. Growth factor stimulation translocates SPRED1 to the plasma membrane, triggering its inhibitory activity. However, it remains unclear whether SPRED1 there acts at the level of Ras or Raf. We show that pharmacological or galectin-1 (Gal-1)-mediated induction of B- and C-Raf-containing dimers translocates SPRED1 to the plasma membrane. This is facilitated in particular by SPRED1 interaction with B-Raf and, via its N terminus, with Gal-1. The physiological significance of these novel interactions is supported by two Legius syndrome-associated mutations that show diminished binding to both Gal-1 and B-Raf. On the plasma membrane, SPRED1 becomes enriched in acidic membrane domains to specifically perturb membrane organization and extracellular signal-regulated kinase (ERK) signaling of active K-ras4B (here, K-ras) but not H-ras. However, SPRED1 also blocks on the nanoscale the positive effects of Gal-1 on H-ras. Therefore, a combinatorial expression of SPRED1 and Gal-1 potentially regulates specific patterns of K-ras- and H-ras-dependent signaling output. More broadly, our results open up the possibility that related SPRED and Sprouty proteins act in a similar Ras and Raf isoform-specific manner.
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