1
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Philips EA, Liu J, Kvalvaag A, Mørch AM, Tocheva AS, Ng C, Liang H, Ahearn IM, Pan R, Luo CC, Leithner A, Qin Z, Zhou Y, Garcia-España A, Mor A, Littman DR, Dustin ML, Wang J, Kong XP. Transmembrane domain-driven PD-1 dimers mediate T cell inhibition. Sci Immunol 2024; 9:eade6256. [PMID: 38457513 DOI: 10.1126/sciimmunol.ade6256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 02/15/2024] [Indexed: 03/10/2024]
Abstract
Programmed cell death-1 (PD-1) is a potent immune checkpoint receptor on T lymphocytes. Upon engagement by its ligands, PD-L1 or PD-L2, PD-1 inhibits T cell activation and can promote immune tolerance. Antagonism of PD-1 signaling has proven effective in cancer immunotherapy, and conversely, agonists of the receptor may have a role in treating autoimmune disease. Some immune receptors function as dimers, but PD-1 has been considered monomeric. Here, we show that PD-1 and its ligands form dimers as a consequence of transmembrane domain interactions and that propensity for dimerization correlates with the ability of PD-1 to inhibit immune responses, antitumor immunity, cytotoxic T cell function, and autoimmune tissue destruction. These observations contribute to our understanding of the PD-1 axis and how it can potentially be manipulated for improved treatment of cancer and autoimmune diseases.
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Affiliation(s)
- Elliot A Philips
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Jia Liu
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Audun Kvalvaag
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
- Institute for Cancer Research, Oslo University Hospital, Oslo, 0379, Norway
| | - Alexander M Mørch
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Anna S Tocheva
- Department of Genetics and Genomic Sciences, Icahn School of Medicine, New York, NY 10029, USA
| | - Charles Ng
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Hong Liang
- Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ian M Ahearn
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Ruimin Pan
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Christina C Luo
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Alexander Leithner
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Zhihua Qin
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Yong Zhou
- Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Antonio Garcia-España
- Research Unit, Hospital Universitari de Tarragona Joan XXIII, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, Tarragona, Spain
| | - Adam Mor
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, NY 10032, USA
| | - Dan R Littman
- Department of Genetics and Genomic Sciences, Icahn School of Medicine, New York, NY 10029, USA
- Howard Hughes Medical Institute, New York, NY 10016, USA
| | - Michael L Dustin
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Jun Wang
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Health, New York, NY 10016, USA
| | - Xiang-Peng Kong
- Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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3
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Chen X, Yao H, Kashif M, Revêchon G, Eriksson M, Hu J, Wang T, Liu Y, Tüksammel E, Strömblad S, Ahearn IM, Philips MR, Wiel C, Ibrahim MX, Bergo MO. A small-molecule ICMT inhibitor delays senescence of Hutchinson-Gilford progeria syndrome cells. eLife 2021; 10:63284. [PMID: 33526168 PMCID: PMC7853716 DOI: 10.7554/elife.63284] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 01/19/2021] [Indexed: 12/31/2022] Open
Abstract
A farnesylated and methylated form of prelamin A called progerin causes Hutchinson-Gilford progeria syndrome (HGPS). Inhibiting progerin methylation by inactivating the isoprenylcysteine carboxylmethyltransferase (ICMT) gene stimulates proliferation of HGPS cells and improves survival of Zmpste24-deficient mice. However, we don't know whether Icmt inactivation improves phenotypes in an authentic HGPS mouse model. Moreover, it is unknown whether pharmacologic targeting of ICMT would be tolerated by cells and produce similar cellular effects as genetic inactivation. Here, we show that knockout of Icmt improves survival of HGPS mice and restores vascular smooth muscle cell numbers in the aorta. We also synthesized a potent ICMT inhibitor called C75 and found that it delays senescence and stimulates proliferation of late-passage HGPS cells and Zmpste24-deficient mouse fibroblasts. Importantly, C75 did not influence proliferation of wild-type human cells or Zmpste24-deficient mouse cells lacking Icmt, indicating drug specificity. These results raise hopes that ICMT inhibitors could be useful for treating children with HGPS.
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Affiliation(s)
- Xue Chen
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.,Department of Plastic and Cosmetic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Haidong Yao
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Muhammad Kashif
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Gwladys Revêchon
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Maria Eriksson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Jianjiang Hu
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Ting Wang
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Yiran Liu
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Elin Tüksammel
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Staffan Strömblad
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Ian M Ahearn
- Department of Dermatology, New York University Grossman School of Medicine, New York, United States
| | - Mark R Philips
- Perlmutter Cancer Center, New York University Grossman School of Medicine, New York, United States
| | - Clotilde Wiel
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Mohamed X Ibrahim
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.,Sahlgrenska Center for Cancer Research, Gothenburg, Sweden
| | - Martin O Bergo
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
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Philips EA, Garcia-España A, Tocheva AS, Ahearn IM, Adam KR, Pan R, Mor A, Kong XP. The structural features that distinguish PD-L2 from PD-L1 emerged in placental mammals. J Biol Chem 2019; 295:4372-4380. [PMID: 31882544 DOI: 10.1074/jbc.ac119.011747] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/03/2019] [Indexed: 12/19/2022] Open
Abstract
Programmed cell death protein 1 (PD-1) is an inhibitory receptor on T lymphocytes that is critical for modulating adaptive immunity. As such, it has been successfully exploited for cancer immunotherapy. Programmed death ligand 1 (PD-L1) and PD-L2 are ligands for PD-1; the former is ubiquitously expressed in inflamed tissues, whereas the latter is restricted to antigen-presenting cells. PD-L2 binds to PD-1 with 3-fold stronger affinity compared with PD-L1. To date, this affinity discrepancy has been attributed to a tryptophan (W110PD-L2) that is unique to PD-L2 and has been assumed to fit snuggly into a pocket on the PD-1 surface. Contrary to this model, using surface plasmon resonance to monitor real-time binding of recombinantly-expressed and -purified proteins, we found that W110PD-L2 acts as an "elbow" that helps shorten PD-L2 engagement with PD-1 and therefore lower affinity. Furthermore, we identified a "latch" between the C and D β-strands of the binding face as the source of the PD-L2 affinity advantage. We show that the 3-fold affinity advantage of PD-L2 is the consequence of these two opposing features, the W110PD-L2 "elbow" and a C-D region "latch." Interestingly, using phylogenetic analysis, we found that these features evolved simultaneously upon the emergence of placental mammals, suggesting that PD-L2-affinity tuning was part of the alterations to the adaptive immune system required for placental gestation.
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Affiliation(s)
- Elliot A Philips
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Antonio Garcia-España
- Research Unit, Hospital Universitari de Tarragona Joan XXIII, Institut d'Investigació Sanitària Pere Virgili, Universitat Rovira i Virgili, 43005 Tarragona, Spain
| | - Anna S Tocheva
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, New York 10032
| | - Ian M Ahearn
- Perlmutter Cancer Center, New York University School of Medicine, New York, New York 10016
| | - Kieran R Adam
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, New York 10032
| | - Ruimin Pan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Adam Mor
- Columbia Center for Translational Immunology, Columbia University Medical Center, New York, New York 10032
| | - Xiang-Peng Kong
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
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5
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Court H, Ahearn IM, Amoyel M, Bach EA, Philips MR. Regulation of NOTCH signaling by RAB7 and RAB8 requires carboxyl methylation by ICMT. J Cell Biol 2017; 216:4165-4182. [PMID: 29051265 PMCID: PMC5716267 DOI: 10.1083/jcb.201701053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 08/04/2017] [Accepted: 09/12/2017] [Indexed: 01/15/2023] Open
Abstract
Isoprenylcysteine carboxyl methyltransferase (ICMT) methylesterifies C-terminal prenylcysteine residues of CaaX proteins and some RAB GTPases. Deficiency of either ICMT or NOTCH1 accelerates pancreatic neoplasia in Pdx1-Cre;LSL-KrasG12D mice, suggesting that ICMT is required for NOTCH signaling. We used Drosophila melanogaster wing vein and scutellar bristle development to screen Rab proteins predicted to be substrates for ICMT (ste14 in flies). We identified Rab7 and Rab8 as ICMT substrates that when silenced phenocopy ste14 deficiency. ICMT, RAB7, and RAB8 were all required for efficient NOTCH1 signaling in mammalian cells. Overexpression of RAB8 rescued NOTCH activation after ICMT knockdown both in U2OS cells expressing NOTCH1 and in fly wing vein development. ICMT deficiency induced mislocalization of GFP-RAB7 and GFP-RAB8 from endomembrane to cytosol, enhanced binding to RABGDI, and decreased GTP loading of RAB7 and RAB8. Deficiency of ICMT, RAB7, or RAB8 led to mislocalization and diminished processing of NOTCH1-GFP. Thus, NOTCH signaling requires ICMT in part because it requires methylated RAB7 and RAB8.
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Affiliation(s)
- Helen Court
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Ian M Ahearn
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Marc Amoyel
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, England, UK
| | - Erika A Bach
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Mark R Philips
- Perlmutter Cancer Center, New York University School of Medicine, New York, NY
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6
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Ahearn IM, Gittler J, Shvartsbeyn M, Meehan SA, Pomeranz MK. Linear atrophoderma of Moulin. Dermatol Online J 2015; 21:13030/qt9x28x358. [PMID: 26990347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 12/15/2015] [Indexed: 06/05/2023] Open
Abstract
We present a 40-year-old woman with asymptomatic, linear, hyperpigmented atrophic plaques in a Blaschkoid distribution on the right back and right upper extremity that is consistent with a diagnosis of linear atrophoderma of Moulin. Clinical lesions developed with a biphasic pattern in late adolescence and in adulthood. The pathogenesis of this acquired, progressive Blaschkolinear dermatosis may hold insight into the pathogenesis of this rare dermatologic condition, as well as other dermotoses, which include those resulting from post-zygotic genetic mosaicism.
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7
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Ahearn IM, Gittler J, Shvartsbeyn M, Meehan SA, Pomeranz MK. Linear atrophoderma of Moulin. Dermatol Online J 2015. [DOI: 10.5070/d32112029549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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8
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Ahearn IM, Hu SW, Meehan SA, Latkowski JA. Primary cutaneous follicle-center lymphoma. Dermatol Online J 2015. [DOI: 10.5070/d32012025049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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9
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Ahearn IM, Hu SW, Meehan SA, Latkowski JA. Primary cutaneous follicle-center lymphoma. Dermatol Online J 2014; 20:13030/qt7zg049ct. [PMID: 25526329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023] Open
Abstract
We present a 64-year-old man with a three-year history of pruritic, pink papules and nodules of the face who was found to have a clonal lymphoproliferative B-cell disease that was characterized by a clonal IGH rearrangement. Although morphologic features present in the biopsy specimen were consistent with a reactive process, additional clinicopathologic correlation (anatomic presentation of lesions on the face, the absence of t(14:18) translocation, and bcl-2 and MUM1 expression) reinforced suspicion of a cutaneous B-cell lymphoma. Systemic work-up with CT/PET and a bone marrow biopsy ultimately excluded systemic disease and primary cutaneous follicle-center lymphoma (PCFCL) was a strong diagnostic consideration. The patient was treated with systemic rituximab with a partial resolution of the facial lesions. The case demonstrates both clinical and pathologic challenges to the diagnosis of primary cutaneous B-cell lymphoma (PCBCL). Furthermore, despite a newly refined classification system, the case also specifically highlights the persistent requirement for flexible clinical reasoning and pathologic correlation. Such reasoning is necessary to generate individualized strategies for diagnosis and treatment when cutaneous B-cell lymphoma is suspected.
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Ahearn IM, Tsai FD, Court H, Zhou M, Jennings BC, Ahmed M, Fehrenbacher N, Linder ME, Philips MR. FKBP12 binds to acylated H-ras and promotes depalmitoylation. Mol Cell 2011; 41:173-85. [PMID: 21255728 DOI: 10.1016/j.molcel.2011.01.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 09/07/2010] [Accepted: 11/24/2010] [Indexed: 11/19/2022]
Abstract
A cycle of palmitoylation/depalmitoylation of H-Ras mediates bidirectional trafficking between the Golgi apparatus and the plasma membrane, but nothing is known about how this cycle is regulated. We show that the prolyl isomerase (PI) FKBP12 binds to H-Ras in a palmitoylation-dependent fashion and promotes depalmitoylation. A variety of inhibitors of the PI activity of FKBP12, including FK506, rapamycin, and cycloheximide, increase steady-state palmitoylation. FK506 inhibits retrograde trafficking of H-Ras from the plasma membrane to the Golgi in a proline 179-dependent fashion, augments early GTP loading of Ras in response to growth factors, and promotes H-Ras-dependent neurite outgrowth from PC12 cells. These data demonstrate that FKBP12 regulates H-Ras trafficking by promoting depalmitoylation through cis-trans isomerization of a peptidyl-prolyl bond in proximity to the palmitoylated cysteines.
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Affiliation(s)
- Ian M Ahearn
- Department of Medicine, NYU Langone School of Medicine, 550 First Avenue, New York, NY 10016, USA. 0016, USA
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11
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Abstract
K-Ras is a member of a family of proteins that associate with the plasma membrane by virtue of a lipid modification that inserts into the membrane and a polybasic region that associates with the anionic head groups of inner leaflet phospholipids. In the case of K-Ras, the lipid is a C-terminal farnesyl isoprenoid adjacent to a polylysine sequence. The affinity of K-Ras for the plasma membrane can be modulated by diminishing the net charge of the polybasic region. Among the ways this can be accomplished is phosphorylation by protein kinase C (PKC) of serine 181 within the polybasic region. Phosphorylation at this site regulates a farnesyl-electrostatic switch that controls association of K-Ras with the plasma membrane. Surprisingly, engagement of the farnesyl-electrostatic switch promotes apoptosis. This chapter describes methods for directly analyzing the phosphorylation status of K-Ras using metabolic labeling with (32)P, for indirectly assessing the farnesyl-electrostatic switch by following GFP-tagged K-Ras in live cells, for artificially activating the farnesyl-electrostatic switch by directing the kinase domain of a PKC to activated K-Ras using a Ras-binding domain, and for assessing apoptosis of individual cells using a YFP-tagged caspase 3 biosensor.
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Affiliation(s)
- Steven E Quatela
- Department of Medicine, Cancer Institute, New York University School of Medicine, New York, NY, USA
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12
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Bivona TG, Quatela SE, Bodemann BO, Ahearn IM, Soskis MJ, Mor A, Miura J, Wiener HH, Wright L, Saba SG, Yim D, Fein A, Pérez de Castro I, Li C, Thompson CB, Cox AD, Philips MR. PKC regulates a farnesyl-electrostatic switch on K-Ras that promotes its association with Bcl-XL on mitochondria and induces apoptosis. Mol Cell 2006; 21:481-93. [PMID: 16483930 DOI: 10.1016/j.molcel.2006.01.012] [Citation(s) in RCA: 366] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2005] [Revised: 12/12/2005] [Accepted: 01/05/2006] [Indexed: 01/07/2023]
Abstract
K-Ras associates with the plasma membrane (PM) through farnesylation that functions in conjunction with an adjacent polybasic sequence. We show that phosphorylation by protein kinase C (PKC) of S181 within the polybasic region promotes rapid dissociation of K-Ras from the PM and association with intracellular membranes, including the outer membrane of mitochondria where phospho-K-Ras interacts with Bcl-XL. PKC agonists promote apoptosis of cells transformed with oncogenic K-Ras in a S181-dependent manner. K-Ras with a phosphomimetic residue at position 181 induces apoptosis via a pathway that requires Bcl-XL. The PKC agonist bryostatin-1 inhibited the growth in vitro and in vivo of cells transformed with oncogenic K-Ras in a S181-dependent fashion. These data demonstrate that the location and function of K-Ras are regulated directly by PKC and suggest an approach to therapy of K-Ras-dependent tumors with agents that stimulate phosphorylation of S181.
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Affiliation(s)
- Trever G Bivona
- Department of Cell Biology, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA
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13
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Abstract
Rap1 and Ras are closely related GTPases that share some effectors but have distinct functions. We studied the subcellular localization of Rap1 and its sites of activation in living cells. Both GFP-tagged Rap1 and endogenous Rap1 were localized to the plasma membrane (PM) and endosomes. The PM association of GFP-Rap1 was dependent on GTP binding, and GFP-Rap1 was rapidly up-regulated on this compartment in response to mitogens, a process blocked by inhibitors of endosome recycling. A novel fluorescent probe for GTP-bound Rap1 revealed that this GTPase was transiently activated only on the PM of both fibroblasts and T cells. Activation on the PM was blocked by inhibitors of endosome recycling. Moreover, inhibition of endosome recycling blocked the ability of Rap1 to promote integrin-mediated adhesion of T cells. Thus, unlike Ras, the membrane localizations of Rap1 are dynamically regulated, and the PM is the principle platform from which Rap1 signaling emanates. These observations may explain some of the biological differences between these GTPases.
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Affiliation(s)
- Trever G Bivona
- Deparment of Cell Biology, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA
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14
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Bivona TG, Pérez De Castro I, Ahearn IM, Grana TM, Chiu VK, Lockyer PJ, Cullen PJ, Pellicer A, Cox AD, Philips MR. Phospholipase Cgamma activates Ras on the Golgi apparatus by means of RasGRP1. Nature 2003; 424:694-8. [PMID: 12845332 DOI: 10.1038/nature01806] [Citation(s) in RCA: 348] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2003] [Accepted: 06/09/2003] [Indexed: 11/09/2022]
Abstract
Ras proteins regulate cellular growth and differentiation, and are mutated in 30% of cancers. We have shown recently that Ras is activated on and transmits signals from the Golgi apparatus as well as the plasma membrane but the mechanism of compartmentalized signalling was not determined. Here we show that, in response to Src-dependent activation of phospholipase Cgamma1, the Ras guanine nucleotide exchange factor RasGRP1 translocated to the Golgi where it activated Ras. Whereas Ca(2+) positively regulated Ras on the Golgi apparatus through RasGRP1, the same second messenger negatively regulated Ras on the plasma membrane by means of the Ras GTPase-activating protein CAPRI. Ras activation after T-cell receptor stimulation in Jurkat cells, rich in RasGRP1, was limited to the Golgi apparatus through the action of CAPRI, demonstrating unambiguously a physiological role for Ras on Golgi. Activation of Ras on Golgi also induced differentiation of PC12 cells, transformed fibroblasts and mediated radioresistance. Thus, activation of Ras on Golgi has important biological consequences and proceeds through a pathway distinct from the one that activates Ras on the plasma membrane.
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Affiliation(s)
- Trever G Bivona
- Department of Medicine, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA
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15
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Ranganathan V, Heine WF, Ciccone DN, Rudolph KL, Wu X, Chang S, Hai H, Ahearn IM, Livingston DM, Resnick I, Rosen F, Seemanova E, Jarolim P, DePinho RA, Weaver DT. Rescue of a telomere length defect of Nijmegen breakage syndrome cells requires NBS and telomerase catalytic subunit. Curr Biol 2001; 11:962-6. [PMID: 11448772 DOI: 10.1016/s0960-9822(01)00267-6] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nijmegen breakage syndrome (NBS) is a rare human disease displaying chromosome instability, radiosensitivity, cancer predisposition, immunodeficiency, and other defects [1, 2]. NBS is complexed with MRE11 and RAD50 in a DNA repair complex [3-5] and is localized to telomere ends in association with TRF proteins [6, 7]. We show that blood cells from NBS patients have shortened telomere DNA ends. Likewise, cultured NBS fibroblasts that exhibit a premature growth cessation were observed with correspondingly shortened telomeres. Introduction of the catalytic subunit of telomerase, TERT, was alone sufficient to increase the proliferative capacity of NBS fibroblasts. However, NBS, but not TERT, restores the capacity of NBS cells to survive gamma irradiation damage. Strikingly, NBS promotes telomere elongation in conjunction with TERT in NBS fibroblasts. These results suggest that NBS is a required accessory protein for telomere extension. Since NBS patients have shortened telomeres, these defects may contribute to the chromosome instability and disease associated with NBS patients.
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Affiliation(s)
- V Ranganathan
- Center for Blood Research, 200 Longwood Avenue, Boston, MA 02115, USA
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