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Hutchins CM, Gorfe AA. Intrinsically disordered membrane anchors of Rheb, RhoA and DiRas3 small GTPases: Molecular dynamics, membrane organization, and interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.591151. [PMID: 38712287 PMCID: PMC11071463 DOI: 10.1101/2024.04.25.591151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Protein structure has been well established to play a key role in determining function; however, intrinsically disordered proteins and regions (IDPs and IDRs) defy this paradigm. IDPs and IDRs exist as an ensemble of structures rather than a stable 3D structure yet play essential roles in many cell signaling processes. Nearly all Ras Superfamily GTPases are tethered to membranes by a lipid tail at the end of a flexible IDR. The sequence of these IDRs are key determinants of membrane localization, and interactions between the IDR and the membrane have been shown to affect signaling in RAS proteins through modulation of dynamic membrane organization. Here we utilized atomistic molecular dynamics simulations to study the membrane interactions, conformational dynamics, and lipid sorting of three IDRs from small GTPases Rheb, RhoA and DiRas3 in model membranes representing their physiological target membranes. We found that complementarity between lipidated IDR sequence and target membrane lipid composition is a determinant of conformational plasticity. We also show that electrostatic interactions between anionic lipids and basic residues on IDRs generate semi-stable conformational sub-states, and a lack of these residues leads to greater conformational diversity. Finally, we show that small GTPase IDRs with a polybasic domain alter local lipid composition by segregating anionic membrane lipids, and, in some cases, excluding other lipids from their immediate proximity in favor of anionic lipids.
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2
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Gebregiworgis T, Chan JYL, Kuntz DA, Privé GG, Marshall CB, Ikura M. Crystal structure of NRAS Q61K with a ligand-induced pocket near switch II. Eur J Cell Biol 2024; 103:151414. [PMID: 38640594 DOI: 10.1016/j.ejcb.2024.151414] [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: 01/17/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/21/2024] Open
Abstract
The RAS isoforms (KRAS, HRAS and NRAS) have distinct cancer type-specific profiles. NRAS mutations are the second most prevalent RAS mutations in skin and hematological malignancies. Although RAS proteins were considered undruggable for decades, isoform and mutation-specific investigations have produced successful RAS inhibitors that are either specific to certain mutants, isoforms (pan-KRAS) or target all RAS proteins (pan-RAS). While extensive structural and biochemical investigations have focused mainly on K- and H-RAS mutations, NRAS mutations have received less attention, and the most prevalent NRAS mutations in human cancers, Q61K and Q61R, are rare in K- and H-RAS. This manuscript presents a crystal structure of the NRAS Q61K mutant in the GTP-bound form. Our structure reveals a previously unseen pocket near switch II induced by the binding of a ligand to the active form of the protein. This observation reveals a binding site that can potentially be exploited for development of inhibitors against mutant NRAS. Furthermore, the well-resolved catalytic site of this GTPase bound to native GTP provides insight into the stalled GTP hydrolysis observed for NRAS-Q61K.
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Affiliation(s)
- Teklab Gebregiworgis
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada; Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 5C1, Canada; Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 5W9, Canada.
| | - Jonathan Yui-Lai Chan
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Douglas A Kuntz
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Gilbert G Privé
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada; Department of Biochemistry, University of Toronto, 1 Kings College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Christopher B Marshall
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada.
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada.
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Bildik G, Gray JP, Mao W, Yang H, Ozyurt R, Orellana VR, De Wever O, Carey MS, Bast RC, Lu Z. DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas. Autophagy 2024; 20:675-691. [PMID: 38169324 PMCID: PMC10936598 DOI: 10.1080/15548627.2023.2299516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 12/20/2023] [Indexed: 01/05/2024] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) and low-grade ovarian cancer (LGSOC) are characterized by the prevalence of KRAS oncogene mutations. DIRAS3 is the first endogenous non-RAS protein that heterodimerizes with RAS, disrupts RAS clustering, blocks RAS signaling, and inhibits cancer cell growth. Here, we found that DIRAS3-mediated KRAS inhibition induces ROS-mediated apoptosis in PDAC and LGSOC cells with KRAS mutations, but not in cells with wild-type KRAS, by downregulating NFE2L2/Nrf2 transcription, reducing antioxidants, and inducing oxidative stress. DIRAS3 also induces cytoprotective macroautophagy/autophagy that may protect mutant KRAS cancer cells from oxidative stress, by inhibiting mutant KRAS, activating the STK11/LKB1-PRKAA/AMPK pathway, increasing lysosomal CDKN1B/p27 localization, and inducing autophagic gene expression. Treatment with chloroquine or the novel dimeric chloroquine analog DC661 significantly enhances DIRAS3-mediated inhibition of mutant KRAS tumor cell growth in vitro and in vivo. Taken together, our study demonstrates that DIRAS3 plays a critical role in regulating mutant KRAS-driven oncogenesis in PDAC and LGSOC.Abbreviations: AFR: autophagic flux reporter; ATG: autophagy related; CQ: chloroquine; DCFDA: 2'-7'-dichlorodihydrofluorescein diacetate; DIRAS3: DIRAS family GTPase 3; DOX: doxycycline; KRAS: KRAS proto-oncogene, LGSOC: low-grade serous ovarian cancer; MiT/TFE: microphthalmia family of transcription factors; NAC: N-acetylcysteine; PDAC: pancreatic ductal adenocarcinoma; ROS: reactive oxygen species; TFEB: transcription factor EB.
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Affiliation(s)
- Gamze Bildik
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Joshua P. Gray
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Weiqun Mao
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Hailing Yang
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Rumeysa Ozyurt
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Vivian R. Orellana
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Olivier De Wever
- Laboratory of Experimental Cancer Research, Cancer Research Institute Ghent, Belgium; Department of Human Structure and Repair, Ghent University, Ghent, Belgium
| | - Mark S. Carey
- Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada
| | - Robert C. Bast
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Zhen Lu
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Araya MK, Gorfe AA. Conformational ensemble-dependent lipid recognition and segregation by prenylated intrinsically disordered regions in small GTPases. Commun Biol 2023; 6:1111. [PMID: 37919400 PMCID: PMC10622456 DOI: 10.1038/s42003-023-05487-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/19/2023] [Indexed: 11/04/2023] Open
Abstract
We studied diverse prenylated intrinsically disordered regions (PIDRs) of Ras and Rho family small GTPases using long timescale atomistic molecular dynamics simulations in an asymmetric model membrane of phosphatidylcholine (PC) and phosphatidylserine (PS) lipids. Here we show that conformational plasticity is a key determinant of lipid sorting by polybasic PIDRs and provide evidence for lipid sorting based on both headgroup and acyl chain structures. We further show that conformational ensemble-based lipid recognition is generalizable to all polybasic PIDRs, and that the sequence outside the polybasic domain (PBD) modulates the conformational plasticity, bilayer adsorption, and interactions of PIDRs with membrane lipids. Specifically, we find that palmitoylation, the ratio of basic to acidic residues, and the hydrophobic content of the sequence outside the PBD significantly impact the diversity of conformational substates and hence the extent of conformation-dependent lipid interactions. We thus propose that the PBD is required but not sufficient for the full realization of lipid sorting by prenylated PBD-containing membrane anchors, and that the membrane anchor is not only responsible for high affinity membrane binding but also directs the protein to the right target membrane where it participates in lipid sorting.
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Affiliation(s)
- Mussie K Araya
- McGovern Medical School, University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, 6431 Fannin St., Houston, TX, 77030, USA
| | - Alemayehu A Gorfe
- McGovern Medical School, University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, 6431 Fannin St., Houston, TX, 77030, USA.
- Biochemistry and Cell Biology Program & Therapeutics and Pharmacology Program, UTHealth MD Anderson Cancer Center Graduate School of Biomedical Sciences, Houston, 6431 Fannin St., TX, 77030, USA.
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5
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Shree S, McLean MA, Stephen AG, Sligar SG. Revealing KRas4b topology on the membrane surface. Biochem Biophys Res Commun 2023; 678:122-127. [PMID: 37633182 PMCID: PMC10528110 DOI: 10.1016/j.bbrc.2023.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 08/16/2023] [Indexed: 08/28/2023]
Abstract
KRas4b is a membrane-bound regulatory protein belonging to the family of small GTPases that function as a molecular switch, facilitating signal transduction from activated membrane receptors to intracellular pathways controlling cell growth and proliferation. Oncogenic mutations locking KRas4b in the active GTP state are responsible for nearly 85% of all Ras-driven cancers. Understanding the membrane-bound state of KRas4b is crucial for designing new therapeutic approaches targeting oncogenic KRas-driven signaling pathways. Extensive research demonstrates the significant involvement of the membrane bilayer in Ras-effector interactions, with anionic lipids playing a critical role in determining protein conformations The preferred topology of KRas4b for interacting with signaling partners has been a long-time question. Computational studies suggest a membrane-proximal conformation, while other biophysical methods like neutron reflectivity propose a membrane-distal conformation. To address these gaps, we employed FRET measurements to investigate the conformation of KRas4b. Using fully post-translationally modified KRas4b, we designed a Nanodisc based FRET assay to study KRas4b-membrane interactions. We suggest an extended conformation of KRas4b relative to the membrane surface. Measurement of FRET donor - acceptor distances reveal that a negatively charged membrane surface weakly favors closer association with the membrane surface. Our findings provide insights into the role of anionic lipids in determining the dynamic conformations of KRas4b and shed light on the predominant conformation of its topology on lipid headgroups.
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Affiliation(s)
- Shweta Shree
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - Mark A McLean
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD, 21701, United States
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States.
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Liu J, Arora N, Zhou Y. RAS GTPases and Interleaflet Coupling in the Plasma Membrane. Cold Spring Harb Perspect Biol 2023; 15:a041414. [PMID: 37463719 PMCID: PMC10513163 DOI: 10.1101/cshperspect.a041414] [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] [Indexed: 07/20/2023]
Abstract
RAS genes are frequently mutated in cancer. The primary signaling compartment of wild-type and constitutively active oncogenic mutant RAS proteins is the inner leaflet of the plasma membrane (PM). Thus, a better understanding of the unique environment of the PM inner leaflet is important to shed further light on RAS function. Over the past few decades, an integrated approach of superresolution imaging, molecular dynamic simulations, and biophysical assays has yielded new insights into the capacity of RAS proteins to sort lipids with specific headgroups and acyl chains, to assemble signaling nanoclusters on the inner PM. RAS proteins also sense and respond to changes in components of the outer PM leaflet, including glycophosphatidylinositol-anchored proteins, sphingophospholipids, glycosphingolipids, and galectins, as well as cholesterol that translocates between the two leaflets. Such communication between the inner and outer leaflets of the PM, called interleaflet coupling, allows RAS to potentially integrate extracellular mechanical and electrostatic information with intracellular biochemical signaling events, and reciprocally allows mutant RAS-transformed tumor cells to modify tumor microenvironments. Here, we review RAS-lipid interactions and speculate on potential mechanisms that allow communication between the opposing leaflets of the PM.
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Affiliation(s)
- Junchen Liu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Neha Arora
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Yong Zhou
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
- Biochemistry and Cell Biology Program, Graduate School of Biomedical Sciences, MD Anderson Cancer Center and University of Texas, Houston, Texas 77030, USA
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Araya MK, Gorfe AA. Conformational ensemble dependent lipid recognition and segregation by prenylated intrinsically disordered regions in small GTPases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.11.553039. [PMID: 37609330 PMCID: PMC10441427 DOI: 10.1101/2023.08.11.553039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
We studied diverse prenylated intrinsically disordered regions (PIDRs) of Ras and Rho family small GTPases using long timescale atomistic molecular dynamics simulations in an asymmetric model membrane of phosphatidylcholine (PC) and phosphatidylserine (PS) lipids. We show that conformational plasticity is a key determinant of lipid sorting by polybasic PIDRs and provide evidence for lipid sorting based on both headgroup and acyl chain structures. We further show that conformational ensemble-based lipid recognition is generalizable to all polybasic PIDRs, and that the sequence outside the polybasic domain (PBD) modulates the conformational plasticity, bilayer adsorption, and interactions of PIDRs with membrane lipids. Specifically, we found that palmitoylation, the ratio of basic to acidic residues, and the hydrophobic content of the sequence outside the PBD significantly impact the diversity of conformational substates and hence the extent of conformation-dependent lipid interactions. We thus propose that the PBD is required but not sufficient for the full realization of lipid sorting by prenylated PBD-containing membrane anchors, and that the membrane anchor is not only responsible for high affinity membrane binding but also directs the protein to the right target membrane where it participates in lipid sorting.
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8
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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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Dynamic regulation of RAS and RAS signaling. Biochem J 2023; 480:1-23. [PMID: 36607281 PMCID: PMC9988006 DOI: 10.1042/bcj20220234] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/16/2022] [Accepted: 12/23/2022] [Indexed: 01/07/2023]
Abstract
RAS proteins regulate most aspects of cellular physiology. They are mutated in 30% of human cancers and 4% of developmental disorders termed Rasopathies. They cycle between active GTP-bound and inactive GDP-bound states. When active, they can interact with a wide range of effectors that control fundamental biochemical and biological processes. Emerging evidence suggests that RAS proteins are not simple on/off switches but sophisticated information processing devices that compute cell fate decisions by integrating external and internal cues. A critical component of this compute function is the dynamic regulation of RAS activation and downstream signaling that allows RAS to produce a rich and nuanced spectrum of biological outputs. We discuss recent findings how the dynamics of RAS and its downstream signaling is regulated. Starting from the structural and biochemical properties of wild-type and mutant RAS proteins and their activation cycle, we examine higher molecular assemblies, effector interactions and downstream signaling outputs, all under the aspect of dynamic regulation. We also consider how computational and mathematical modeling approaches contribute to analyze and understand the pleiotropic functions of RAS in health and disease.
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Remodeling of the Plasma Membrane by Surface-Bound Protein Monomers and Oligomers: The Critical Role of Intrinsically Disordered Regions. J Membr Biol 2022; 255:651-663. [PMID: 35930019 PMCID: PMC9718270 DOI: 10.1007/s00232-022-00256-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/07/2022] [Indexed: 12/24/2022]
Abstract
The plasma membrane (PM) of cells is a dynamic structure whose morphology and composition is in constant flux. PM morphologic changes are particularly relevant for the assembly and disassembly of signaling platforms involving surface-bound signaling proteins, as well as for many other mechanochemical processes that occur at the PM surface. Surface-bound membrane proteins (SBMP) require efficient association with the PM for their function, which is often achieved by the coordinated interactions of intrinsically disordered regions (IDRs) and globular domains with membrane lipids. This review focuses on the role of IDR-containing SBMPs in remodeling the composition and curvature of the PM. The ability of IDR-bearing SBMPs to remodel the Gaussian and mean curvature energies of the PM is intimately linked to their ability to sort subsets of phospholipids into nanoclusters. We therefore discuss how IDRs of many SBMPs encode lipid-binding specificity or facilitate cluster formation, both of which increase their membrane remodeling capacity, and how SBMP oligomers alter membrane shape by monolayer surface area expansion and molecular crowding.
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Lee HH, Chen CH, Huang YH, Chiang CH, Huang MY. Biomarkers of Favorable vs. Unfavorable Responses in Locally Advanced Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy. Cells 2022; 11:cells11101611. [PMID: 35626648 PMCID: PMC9139800 DOI: 10.3390/cells11101611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/27/2022] [Accepted: 05/10/2022] [Indexed: 02/04/2023] Open
Abstract
Colorectal cancer is the second leading cause of cancer death globally. The gold standard for locally advanced rectal cancer (LARC) nowadays is preoperative concurrent chemoradiation (CCRT). Approximately three quarters of LARC patients do not achieve pathological complete response and hence suffer from relapse, metastases and inevitable death. The exploration of trustworthy and timely biomarkers for CCRT response is urgently called for. This review focused upon a broad spectrum of biomarkers, including circulating tumor cells, DNA, RNA, oncogenes, tumor suppressor genes, epigenetics, impaired DNA mismatch repair, patient-derived xenografts, in vitro tumor organoids, immunity and microbiomes. Utilizing proper biomarkers can assist in categorizing appropriate patients by the most efficient treatment modality with the best outcome and accompanied by minimal side effects. The purpose of this review is to inspect and analyze accessible data in order to fully realize the promise of precision oncology for rectal cancer patients.
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Affiliation(s)
- Hsin-Hua Lee
- Ph.D. Program in Environmental and Occupational Medicine, National Health Research Institutes, Kaohsiung Medical University, Kaohsiung 807, Taiwan;
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; (C.-H.C.); (C.-H.C.)
- Department of Radiation Oncology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Chien-Hung Chen
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; (C.-H.C.); (C.-H.C.)
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Radiation Oncology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University, Kaohsiung 801, Taiwan
| | - Yu-Hsiang Huang
- Post-Graduate Year Training, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan;
| | - Cheng-Han Chiang
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; (C.-H.C.); (C.-H.C.)
| | - Ming-Yii Huang
- Ph.D. Program in Environmental and Occupational Medicine, National Health Research Institutes, Kaohsiung Medical University, Kaohsiung 807, Taiwan;
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; (C.-H.C.); (C.-H.C.)
- Department of Radiation Oncology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Correspondence: ; Tel.: +886-7-3121101 (ext. 7158)
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Machine learning-driven multiscale modeling reveals lipid-dependent dynamics of RAS signaling proteins. Proc Natl Acad Sci U S A 2022; 119:2113297119. [PMID: 34983849 PMCID: PMC8740753 DOI: 10.1073/pnas.2113297119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2021] [Indexed: 01/17/2023] Open
Abstract
Here we present an unprecedented multiscale simulation platform that enables modeling, hypothesis generation, and discovery across biologically relevant length and time scales to predict mechanisms that can be tested experimentally. We demonstrate that our predictive simulation-experimental validation loop generates accurate insights into RAS-membrane biology. Evaluating over 100,000 correlated simulations, we show that RAS–lipid interactions are dynamic and evolving, resulting in: 1) a reordering and selection of lipid domains in realistic eight-lipid bilayers, 2) clustering of RAS into multimers correlating with specific lipid fingerprints, 3) changes in the orientation of the RAS G-domain impacting its ability to interact with effectors, and 4) demonstration that RAS–RAS G-domain interfaces are nonspecific in these putative signaling domains. RAS is a signaling protein associated with the cell membrane that is mutated in up to 30% of human cancers. RAS signaling has been proposed to be regulated by dynamic heterogeneity of the cell membrane. Investigating such a mechanism requires near-atomistic detail at macroscopic temporal and spatial scales, which is not possible with conventional computational or experimental techniques. We demonstrate here a multiscale simulation infrastructure that uses machine learning to create a scale-bridging ensemble of over 100,000 simulations of active wild-type KRAS on a complex, asymmetric membrane. Initialized and validated with experimental data (including a new structure of active wild-type KRAS), these simulations represent a substantial advance in the ability to characterize RAS-membrane biology. We report distinctive patterns of local lipid composition that correlate with interfacially promiscuous RAS multimerization. These lipid fingerprints are coupled to RAS dynamics, predicted to influence effector binding, and therefore may be a mechanism for regulating cell signaling cascades.
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