1
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Wang JCK, Baddock HT, Mafi A, Foe IT, Bratkowski M, Lin TY, Jensvold ZD, Preciado López M, Stokoe D, Eaton D, Hao Q, Nile AH. Structure of the p53 degradation complex from HPV16. Nat Commun 2024; 15:1842. [PMID: 38418456 PMCID: PMC10902388 DOI: 10.1038/s41467-024-45920-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 02/06/2024] [Indexed: 03/01/2024] Open
Abstract
Human papillomavirus (HPV) is a significant contributor to the global cancer burden, and its carcinogenic activity is facilitated in part by the HPV early protein 6 (E6), which interacts with the E3-ligase E6AP, also known as UBE3A, to promote degradation of the tumor suppressor, p53. In this study, we present a single-particle cryoEM structure of the full-length E6AP protein in complex with HPV16 E6 (16E6) and p53, determined at a resolution of ~3.3 Å. Our structure reveals extensive protein-protein interactions between 16E6 and E6AP, explaining their picomolar binding affinity. These findings shed light on the molecular basis of the ternary complex, which has been pursued as a potential therapeutic target for HPV-driven cervical, anal, and oropharyngeal cancers over the last two decades. Understanding the structural and mechanistic underpinnings of this complex is crucial for developing effective therapies to combat HPV-induced cancers. Our findings may help to explain why previous attempts to disrupt this complex have failed to generate therapeutic modalities and suggest that current strategies should be reevaluated.
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Affiliation(s)
- John C K Wang
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Hannah T Baddock
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Amirhossein Mafi
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Ian T Foe
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Matthew Bratkowski
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Ting-Yu Lin
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Zena D Jensvold
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | | | - David Stokoe
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Dan Eaton
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Qi Hao
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
| | - Aaron H Nile
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
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2
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Ye X, Zhang P, Tao J, Wang JCK, Mafi A, Grob NM, Quartararo AJ, Baddock HT, Chan LJG, McAllister FE, Foe I, Loas A, Eaton DL, Hao Q, Nile AH, Pentelute BL. Discovery of reactive peptide inhibitors of human papillomavirus oncoprotein E6. Chem Sci 2023; 14:12484-12497. [PMID: 38020382 PMCID: PMC10646941 DOI: 10.1039/d3sc02782a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 06/01/2023] [Accepted: 08/22/2023] [Indexed: 12/01/2023] Open
Abstract
Human papillomavirus (HPV) infections account for nearly all cervical cancer cases, which is the fourth most common cancer in women worldwide. High-risk variants, including HPV16, drive tumorigenesis in part by promoting the degradation of the tumor suppressor p53. This degradation is mediated by the HPV early protein 6 (E6), which recruits the E3 ubiquitin ligase E6AP and redirects its activity towards ubiquitinating p53. Targeting the protein interaction interface between HPV E6 and E6AP is a promising modality to mitigate HPV-mediated degradation of p53. In this study, we designed a covalent peptide inhibitor, termed reactide, that mimics the E6AP LXXLL binding motif by selectively targeting cysteine 58 in HPV16 E6 with quantitative conversion. This reactide provides a starting point in the development of covalent peptidomimetic inhibitors for intervention against HPV-driven cancers.
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Affiliation(s)
- Xiyun Ye
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Peiyuan Zhang
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Jason Tao
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - John C K Wang
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Amirhossein Mafi
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Nathalie M Grob
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Anthony J Quartararo
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Hannah T Baddock
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Leanne J G Chan
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Fiona E McAllister
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Ian Foe
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Andrei Loas
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
| | - Dan L Eaton
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Qi Hao
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Aaron H Nile
- Calico Life Sciences LLC 1170 Veterans Boulevard South San Francisco CA 94080 USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
- The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology 500 Main Street Cambridge MA 02142 USA
- Center for Environmental Health Sciences, Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA
- Broad Institute of MIT and Harvard 415 Main Street Cambridge MA 02142 USA
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3
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Chen XR, Poudel L, Hong Z, Johnen P, Katti S, Tripathi A, Nile AH, Green SM, Khan D, Schaaf G, Bono F, Bankaitis VA, Igumenova TI. Mechanisms by which small molecules of diverse chemotypes arrest Sec14 lipid transfer activity. J Biol Chem 2023; 299:102861. [PMID: 36603766 PMCID: PMC9898755 DOI: 10.1016/j.jbc.2022.102861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/05/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023] Open
Abstract
Phosphatidylinositol (PtdIns) transfer proteins (PITPs) enhance the activities of PtdIns 4-OH kinases that generate signaling pools of PtdIns-4-phosphate. In that capacity, PITPs serve as key regulators of lipid signaling in eukaryotic cells. Although the PITP phospholipid exchange cycle is the engine that stimulates PtdIns 4-OH kinase activities, the underlying mechanism is not understood. Herein, we apply an integrative structural biology approach to investigate interactions of the yeast PITP Sec14 with small-molecule inhibitors (SMIs) of its phospholipid exchange cycle. Using a combination of X-ray crystallography, solution NMR spectroscopy, and atomistic MD simulations, we dissect how SMIs compete with native Sec14 phospholipid ligands and arrest phospholipid exchange. Moreover, as Sec14 PITPs represent new targets for the development of next-generation antifungal drugs, the structures of Sec14 bound to SMIs of diverse chemotypes reported in this study will provide critical information required for future structure-based design of next-generation lead compounds directed against Sec14 PITPs of virulent fungi.
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Affiliation(s)
- Xiao-Ru Chen
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Lokendra Poudel
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Zebin Hong
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Philipp Johnen
- Institute for Crop Science and Resource Conservation, Universität Bonn, Bonn, Germany
| | - Sachin Katti
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Ashutosh Tripathi
- Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Aaron H Nile
- Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Savana M Green
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA; Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA
| | - Danish Khan
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA
| | - Gabriel Schaaf
- Institute for Crop Science and Resource Conservation, Universität Bonn, Bonn, Germany
| | - Fulvia Bono
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Vytas A Bankaitis
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA; Department of Cell Biology & Genetics, Texas A&M University, College Station, Texas, USA.
| | - Tatyana I Igumenova
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas USA.
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4
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Judge RA, Sridar J, Tunyasuvunakool K, Jain R, Wang JCK, Ouch C, Xu J, Mafi A, Nile AH, Remarcik C, Smith CL, Ghosh C, Xu C, Stoll V, Jumper J, Singh AH, Eaton D, Hao Q. Author Correction: Structure of the PAPP-A BP5 complex reveals mechanism of substrate recognition. Nat Commun 2022; 13:5694. [PMID: 36171222 PMCID: PMC9519949 DOI: 10.1038/s41467-022-33522-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | - Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Rinku Jain
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Aaron H Nile
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | - Crystal Ghosh
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Stoll
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | | | - Amoolya H Singh
- Calico Life Sciences LLC, South San Francisco, CA, USA.,GRAIL, Menlo Park, CA, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA.
| | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA.
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5
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Judge RA, Sridar J, Tunyasunvunakool K, Jain R, Wang JCK, Ouch C, Xu J, Mafi A, Nile AH, Remarcik C, Smith CL, Ghosh C, Xu C, Stoll V, Jumper J, Singh AH, Eaton D, Hao Q. Structure of the PAPP-A BP5 complex reveals mechanism of substrate recognition. Nat Commun 2022; 13:5500. [PMID: 36127359 PMCID: PMC9489782 DOI: 10.1038/s41467-022-33175-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 03/31/2022] [Accepted: 09/03/2022] [Indexed: 11/09/2022] Open
Abstract
Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-ABP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.
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Affiliation(s)
| | - Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Rinku Jain
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Aaron H Nile
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | - Crystal Ghosh
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Stoll
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | | | - Amoolya H Singh
- Calico Life Sciences LLC, South San Francisco, CA, USA.,GRAIL, Menlo Park, CA, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA.
| | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA.
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6
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Sugiura T, Nakao H, Ikeda K, Khan D, Nile AH, Bankaitis VA, Nakano M. Biophysical parameters of the Sec14 phospholipid exchange cycle - Effect of lipid packing in membranes. Biochim Biophys Acta Biomembr 2020; 1863:183450. [PMID: 32828847 DOI: 10.1016/j.bbamem.2020.183450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 11/28/2022]
Abstract
Sec14, a yeast phosphatidylinositol/phosphatidylcholine transfer protein, functions at the trans-Golgi membranes. It lacks domains involved in protein-protein or protein-lipid interactions and consists solely of the Sec14 domain; hence, the mechanism underlying Sec14 function at proper sites remains unclear. In this study, we focused on the lipid packing of membranes and evaluated its association with in vitro Sec14 lipid transfer activity. Phospholipid transfer assays using pyrene-labelled phosphatidylcholine suggested that increased membrane curvature as well as the incorporation of phosphatidylethanolamine accelerated the lipid transfer. The quantity of membrane-bound Sec14 significantly increased in these membranes, indicating that "packing defects" of the membranes promote the membrane binding and phospholipid transfer of Sec14. Increased levels of phospholipid unsaturation promoted Sec14-mediated PC transfer, but had little effect on the membrane binding of the protein. Our results demonstrate the possibility that the location and function of Sec14 are regulated by the lipid packing states produced by a translocase activity at the trans-Golgi network.
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Affiliation(s)
- Taichi Sugiura
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Danish Khan
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128, USA
| | - Aaron H Nile
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX 77843-1114, USA
| | - Vytas A Bankaitis
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128, USA; Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX 77843-1114, USA
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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7
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Hansen S, Nile AH, Mehta SC, Fuhrmann J, Hannoush RN. Lead Optimization Yields High Affinity Frizzled 7-Targeting Peptides That Modulate Clostridium difficile Toxin B Pathogenicity in Epithelial Cells. J Med Chem 2019; 62:7739-7750. [PMID: 31429553 DOI: 10.1021/acs.jmedchem.9b00500] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Frizzled 7 (FZD7) receptors have been shown to play a central role in intestinal stem cell regeneration and, more recently, in Clostridium difficile pathogenesis. Yet, targeting FZD7 receptors with small ligands has not been explored as an approach to block C. difficile pathogenesis. Here, we report the discovery of high affinity peptides that selectively bind to FZD7 receptors. We describe an integrated approach for lead optimization, utilizing structure-based rational design and directed evolution, to enhance the peptide binding affinity while still maintaining FZD7 receptor selectivity. This work yielded new peptide leads with picomolar binding constants to FZD7 as measured by biophysical methods. The new peptides block the interaction between C. difficile toxin B (TcdB) and FZD receptors and perturb C. difficile pathogenesis in epithelial cells. As such, our findings provide a proof of concept that targeting FZD receptors could be a viable pharmacological approach to protect epithelial cells from TcdB pathogenicity.
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8
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Abstract
Wnt signaling regulates physiological processes ranging from cell differentiation to bone formation. Dysregulation of Wnt signaling is linked to several human ailments, including colorectal, pancreatic, and breast cancers. As such, modulation of this pathway has been an attractive strategy for therapeutic development of anticancer agents. Since the discovery of Wnt proteins more than 35 years ago, research efforts continue to focus on understanding the biochemistry of their molecular interactions and their biological functions. Wnt is a secreted glycoprotein covalently modified with a cis-unsaturated fatty acyl group at a conserved serine residue, and this modification is required for Wnt secretion and activity. To initiate signaling, Wnt proteins bind to cell-surface Frizzled (FZD) receptors, but the molecular basis for recognition of Wnt's fatty acyl moiety by the extracellular cysteine-rich domain of FZD has become clear only very recently. Here, we review the most recent developments in the field, focusing on structural and biochemical studies of the FZD receptor family and highlighting new insights into their molecular arrangement and mode of regulation by cis-unsaturated fatty acids. Additionally, we examine how other lipid-binding proteins recognize fatty acyl chains on Wnt proteins in the regulation of Wnt secretion and activities. Altogether, this perspective expands our understanding of fatty acid–protein interactions in the FZD system and provides a basis for guiding future research in the field.
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Affiliation(s)
- Aaron H Nile
- From the Department of Early Discovery Biochemistry, Genentech, South San Francisco, California 94080
| | - Rami N Hannoush
- From the Department of Early Discovery Biochemistry, Genentech, South San Francisco, California 94080
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9
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Sugiura T, Takahashi C, Chuma Y, Fukuda M, Yamada M, Yoshida U, Nakao H, Ikeda K, Khan D, Nile AH, Bankaitis VA, Nakano M. Biophysical Parameters of the Sec14 Phospholipid Exchange Cycle. Biophys J 2018; 116:92-103. [PMID: 30580923 DOI: 10.1016/j.bpj.2018.11.3131] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [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: 09/21/2018] [Revised: 10/24/2018] [Accepted: 11/28/2018] [Indexed: 12/23/2022] Open
Abstract
Sec14, the major yeast phosphatidylcholine (PC)/phosphatidylinositol (PI) transfer protein (PITP), coordinates PC and PI metabolism to facilitate an appropriate and essential lipid signaling environment for membrane trafficking from trans-Golgi membranes. The Sec14 PI/PC exchange cycle is essential for its essential biological activity, but fundamental aspects of how this PITP executes its lipid transfer cycle remain unknown. To address some of these outstanding issues, we applied time-resolved small-angle neutron scattering for the determination of protein-mediated intervesicular movement of deuterated and hydrogenated phospholipids in vitro. Quantitative analysis by small-angle neutron scattering revealed that Sec14 PI- and PC-exchange activities were sensitive to both the lipid composition and curvature of membranes. Moreover, we report that these two parameters regulate lipid exchange activity via distinct mechanisms. Increased membrane curvature promoted both membrane binding and lipid exchange properties of Sec14, indicating that this PITP preferentially acts on the membrane site with a convexly curved face. This biophysical property likely constitutes part of a mechanism by which spatial specificity of Sec14 function is determined in cells. Finally, wild-type Sec14, but not a mixture of Sec14 proteins specifically deficient in either PC- or PI-binding activity, was able to effect a net transfer of PI or PC down opposing concentration gradients in vitro.
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Affiliation(s)
- Taichi Sugiura
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Chisato Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yusuke Chuma
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Masakazu Fukuda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Makiko Yamada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Ukyo Yoshida
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Hiroyuki Nakao
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Keisuke Ikeda
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Danish Khan
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Aaron H Nile
- Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, Texas
| | - Vytas A Bankaitis
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, Texas; Department of Molecular & Cellular Medicine, Texas A&M Health Sciences Center, College Station, Texas
| | - Minoru Nakano
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
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10
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Nile AH, de Sousa E Melo F, Mukund S, Piskol R, Hansen S, Zhou L, Zhang Y, Fu Y, Gogol EB, Kömüves LG, Modrusan Z, Angers S, Franke Y, Koth C, Fairbrother WJ, Wang W, de Sauvage FJ, Hannoush RN. Publisher Correction: A selective peptide inhibitor of Frizzled 7 receptors disrupts intestinal stem cells. Nat Chem Biol 2018; 14:902. [PMID: 29728602 DOI: 10.1038/s41589-018-0069-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The version of this article originally published contained older versions of the Life Sciences Reporting Summary and the Supplementary Text and Figures. The error has been corrected in the HTML and PDF versions of the article.
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Affiliation(s)
- Aaron H Nile
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | | | - Susmith Mukund
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Robert Piskol
- Department of Bioinformatics and Computational Biology, Genentech, South San Francisco, CA, USA
| | - Simon Hansen
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Lijuan Zhou
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Yingnan Zhang
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Yue Fu
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Emily B Gogol
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - László G Kömüves
- Department of Pathology, Genentech, South San Francisco, CA, USA
| | - Zora Modrusan
- Department of Molecular Biology, Genentech, South San Francisco, CA, USA
| | - Stephane Angers
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Yvonne Franke
- Department of Biomolecular Resources, Genentech, South San Francisco, CA, USA
| | - Christopher Koth
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Wayne J Fairbrother
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Weiru Wang
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | | | - Rami N Hannoush
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA.
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11
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Nile AH, de Sousa E Melo F, Mukund S, Piskol R, Hansen S, Zhou L, Zhang Y, Fu Y, Gogol EB, Kömüves LG, Modrusan Z, Angers S, Franke Y, Koth C, Fairbrother WJ, Wang W, de Sauvage FJ, Hannoush RN. A selective peptide inhibitor of Frizzled 7 receptors disrupts intestinal stem cells. Nat Chem Biol 2018; 14:582-590. [PMID: 29632413 DOI: 10.1038/s41589-018-0035-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/21/2018] [Indexed: 02/06/2023]
Abstract
Regeneration of the adult intestinal epithelium is mediated by a pool of cycling stem cells, which are located at the base of the crypt, that express leucine-rich-repeat-containing G-protein-coupled receptor 5 (LGR5). The Frizzled (FZD) 7 receptor (FZD7) is enriched in LGR5+ intestinal stem cells and plays a critical role in their self-renewal. Yet, drug discovery approaches and structural bases for targeting specific FZD isoforms remain poorly defined. FZD proteins interact with Wnt signaling proteins via, in part, a lipid-binding groove on the extracellular cysteine-rich domain (CRD) of the FZD receptor. Here we report the identification of a potent peptide that selectively binds to the FZD7 CRD at a previously uncharacterized site and alters the conformation of the CRD and the architecture of its lipid-binding groove. Treatment with the FZD7-binding peptide impaired Wnt signaling in cultured cells and stem cell function in intestinal organoids. Together, our data illustrate that targeting the lipid-binding groove holds promise as an approach for achieving isoform-selective FZD receptor inhibition.
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Affiliation(s)
- Aaron H Nile
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | | | - Susmith Mukund
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Robert Piskol
- Department of Bioinformatics and Computational Biology, Genentech, South San Francisco, CA, USA
| | - Simon Hansen
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Lijuan Zhou
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Yingnan Zhang
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Yue Fu
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Emily B Gogol
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - László G Kömüves
- Department of Pathology, Genentech, South San Francisco, CA, USA
| | - Zora Modrusan
- Department of Molecular Biology, Genentech, South San Francisco, CA, USA
| | - Stephane Angers
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Yvonne Franke
- Department of Biomolecular Resources, Genentech, South San Francisco, CA, USA
| | - Christopher Koth
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Wayne J Fairbrother
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA
| | - Weiru Wang
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | | | - Rami N Hannoush
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, CA, USA.
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13
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Lee AY, St Onge RP, Proctor MJ, Wallace IM, Nile AH, Spagnuolo PA, Jitkova Y, Gronda M, Wu Y, Kim MK, Cheung-Ong K, Torres NP, Spear ED, Han MKL, Schlecht U, Suresh S, Duby G, Heisler LE, Surendra A, Fung E, Urbanus ML, Gebbia M, Lissina E, Miranda M, Chiang JH, Aparicio AM, Zeghouf M, Davis RW, Cherfils J, Boutry M, Kaiser CA, Cummins CL, Trimble WS, Brown GW, Schimmer AD, Bankaitis VA, Nislow C, Bader GD, Giaever G. Mapping the cellular response to small molecules using chemogenomic fitness signatures. Science 2014; 344:208-11. [PMID: 24723613 DOI: 10.1126/science.1250217] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Genome-wide characterization of the in vivo cellular response to perturbation is fundamental to understanding how cells survive stress. Identifying the proteins and pathways perturbed by small molecules affects biology and medicine by revealing the mechanisms of drug action. We used a yeast chemogenomics platform that quantifies the requirement for each gene for resistance to a compound in vivo to profile 3250 small molecules in a systematic and unbiased manner. We identified 317 compounds that specifically perturb the function of 121 genes and characterized the mechanism of specific compounds. Global analysis revealed that the cellular response to small molecules is limited and described by a network of 45 major chemogenomic signatures. Our results provide a resource for the discovery of functional interactions among genes, chemicals, and biological processes.
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Affiliation(s)
- Anna Y Lee
- The Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
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14
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Ren J, Pei-Chen Lin C, Pathak MC, Temple BRS, Nile AH, Mousley CJ, Duncan MC, Eckert DM, Leiker TJ, Ivanova PT, Myers DS, Murphy RC, Brown HA, Verdaasdonk J, Bloom KS, Ortlund EA, Neiman AM, Bankaitis VA. A phosphatidylinositol transfer protein integrates phosphoinositide signaling with lipid droplet metabolism to regulate a developmental program of nutrient stress-induced membrane biogenesis. Mol Biol Cell 2014; 25:712-27. [PMID: 24403601 PMCID: PMC3937096 DOI: 10.1091/mbc.e13-11-0634] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [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: 11/01/2013] [Revised: 12/10/2013] [Accepted: 12/23/2013] [Indexed: 12/31/2022] Open
Abstract
Lipid droplet (LD) utilization is an important cellular activity that regulates energy balance and release of lipid second messengers. Because fatty acids exhibit both beneficial and toxic properties, their release from LDs must be controlled. Here we demonstrate that yeast Sfh3, an unusual Sec14-like phosphatidylinositol transfer protein, is an LD-associated protein that inhibits lipid mobilization from these particles. We further document a complex biochemical diversification of LDs during sporulation in which Sfh3 and select other LD proteins redistribute into discrete LD subpopulations. The data show that Sfh3 modulates the efficiency with which a neutral lipid hydrolase-rich LD subclass is consumed during biogenesis of specialized membrane envelopes that package replicated haploid meiotic genomes. These results present novel insights into the interface between phosphoinositide signaling and developmental regulation of LD metabolism and unveil meiosis-specific aspects of Sfh3 (and phosphoinositide) biology that are invisible to contemporary haploid-centric cell biological, proteomic, and functional genomics approaches.
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Affiliation(s)
- Jihui Ren
- Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090
- Department of Molecular and Cellular Medicine, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-1114
| | - Coney Pei-Chen Lin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Manish C. Pathak
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-4250
| | - Brenda R. S. Temple
- R. L. Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7260
| | - Aaron H. Nile
- Department of Molecular and Cellular Medicine, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-1114
| | - Carl J. Mousley
- Department of Molecular and Cellular Medicine, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-1114
| | - Mara C. Duncan
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Debra M. Eckert
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112-5650
| | - Thomas J. Leiker
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, CO 80045-0511
| | - Pavlina T. Ivanova
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-6600
| | - David S. Myers
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-6600
| | - Robert C. Murphy
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, CO 80045-0511
| | - H. Alex Brown
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-6600
| | - Jolien Verdaasdonk
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Kerry S. Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Eric A. Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-4250
| | - Aaron M. Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215
| | - Vytas A. Bankaitis
- Department of Molecular and Cellular Medicine, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-1114
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15
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Nile AH, Tripathi A, Yuan P, Mousley CJ, Suresh S, Wallace IM, Shah SD, Pohlhaus DT, Temple B, Nislow C, Giaever G, Tropsha A, Davis RW, St Onge RP, Bankaitis VA. PITPs as targets for selectively interfering with phosphoinositide signaling in cells. Nat Chem Biol 2014; 10:76-84. [PMID: 24292071 PMCID: PMC4059020 DOI: 10.1038/nchembio.1389] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [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: 04/05/2013] [Accepted: 10/02/2013] [Indexed: 01/26/2023]
Abstract
Sec14-like phosphatidylinositol transfer proteins (PITPs) integrate diverse territories of intracellular lipid metabolism with stimulated phosphatidylinositol-4-phosphate production and are discriminating portals for interrogating phosphoinositide signaling. Yet, neither Sec14-like PITPs nor PITPs in general have been exploited as targets for chemical inhibition for such purposes. Herein, we validate what is to our knowledge the first small-molecule inhibitors (SMIs) of the yeast PITP Sec14. These SMIs are nitrophenyl(4-(2-methoxyphenyl)piperazin-1-yl)methanones (NPPMs) and are effective inhibitors in vitro and in vivo. We further establish that Sec14 is the sole essential NPPM target in yeast and that NPPMs exhibit exquisite targeting specificities for Sec14 (relative to related Sec14-like PITPs), propose a mechanism for how NPPMs exert their inhibitory effects and demonstrate that NPPMs exhibit exquisite pathway selectivity in inhibiting phosphoinositide signaling in cells. These data deliver proof of concept that PITP-directed SMIs offer new and generally applicable avenues for intervening with phosphoinositide signaling pathways with selectivities superior to those afforded by contemporary lipid kinase-directed strategies.
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Affiliation(s)
- Aaron H. Nile
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
| | - Ashutosh Tripathi
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Peihua Yuan
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
| | - Carl J. Mousley
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
| | - Sundari Suresh
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Iain Michael Wallace
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Sweety D. Shah
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
| | - Denise Teotico Pohlhaus
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Brenda Temple
- R. L. Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7260 USA
| | - Corey Nislow
- Faculty of Pharmaceutical Sciences,, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Guri Giaever
- Faculty of Pharmaceutical Sciences,, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Alexander Tropsha
- Laboratory for Molecular Modeling, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7355 USA
| | - Ronald W. Davis
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Robert P. St Onge
- Department of Biochemistry, Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304
| | - Vytas A. Bankaitis
- Department of Molecular & Cellular Medicine, Department of Biochemistry & Biophysics, Department of Chemistry, Texas A&M University, College Station, Texas 77843-1114 USA
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7090 USA
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Mousley CJ, Yuan P, Gaur NA, Trettin KD, Nile AH, Deminoff SJ, Dewar BJ, Wolpert M, Macdonald JM, Herman PK, Hinnebusch AG, Bankaitis VA. A sterol-binding protein integrates endosomal lipid metabolism with TOR signaling and nitrogen sensing. Cell 2012; 148:702-15. [PMID: 22341443 DOI: 10.1016/j.cell.2011.12.026] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [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: 10/15/2010] [Revised: 10/13/2011] [Accepted: 12/05/2011] [Indexed: 11/18/2022]
Abstract
Kes1, and other oxysterol-binding protein superfamily members, are involved in membrane and lipid trafficking through trans-Golgi network (TGN) and endosomal systems. We demonstrate that Kes1 represents a sterol-regulated antagonist of TGN/endosomal phosphatidylinositol-4-phosphate signaling. This regulation modulates TOR activation by amino acids and dampens gene expression driven by Gcn4, the primary transcriptional activator of the general amino acid control regulon. Kes1-mediated repression of Gcn4 transcription factor activity is characterized by nonproductive Gcn4 binding to its target sequences, involves TGN/endosome-derived sphingolipid signaling, and requires activity of the cyclin-dependent kinase 8 (CDK8) module of the enigmatic "large Mediator" complex. These data describe a pathway by which Kes1 integrates lipid metabolism with TORC1 signaling and nitrogen sensing.
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Affiliation(s)
- Carl J Mousley
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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Bankaitis VA, Ile KE, Nile AH, Ren J, Ghosh R, Schaaf G. Thoughts on Sec14-like nanoreactors and phosphoinositide signaling. Adv Biol Regul 2012; 52:115-21. [PMID: 22776890 DOI: 10.1016/j.jbior.2011.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 11/11/2011] [Indexed: 10/28/2022]
Affiliation(s)
- Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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Abstract
Inositol and phosphoinositide signaling pathways represent major regulatory systems in eukaryotes. The physiological importance of these pathways is amply demonstrated by the variety of diseases that involve derangements in individual steps in inositide and phosphoinositide production and degradation. These diseases include numerous cancers, lipodystrophies and neurological syndromes. Phosphatidylinositol transfer proteins (PITPs) are emerging as fascinating regulators of phosphoinositide metabolism. Recent advances identify PITPs (and PITP-like proteins) to be coincidence detectors, which spatially and temporally coordinate the activities of diverse aspects of the cellular lipid metabolome with phosphoinositide signaling. These insights are providing new ideas regarding mechanisms of inherited mammalian diseases associated with derangements in the activities of PITPs and PITP-like proteins.
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Affiliation(s)
- Aaron H Nile
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Aby Grabon
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
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Coffman VC, Nile AH, Lee IJ, Liu H, Wu JQ. Roles of formin nodes and myosin motor activity in Mid1p-dependent contractile-ring assembly during fission yeast cytokinesis. Mol Biol Cell 2010; 20:5195-210. [PMID: 19864459 DOI: 10.1091/mbc.e09-05-0428] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Two prevailing models have emerged to explain the mechanism of contractile-ring assembly during cytokinesis in the fission yeast Schizosaccharomyces pombe: the spot/leading cable model and the search, capture, pull, and release (SCPR) model. We tested some of the basic assumptions of the two models. Monte Carlo simulations of the SCPR model require that the formin Cdc12p is present in >30 nodes from which actin filaments are nucleated and captured by myosin-II in neighboring nodes. The force produced by myosin motors pulls the nodes together to form a compact contractile ring. Live microscopy of cells expressing Cdc12p fluorescent fusion proteins shows for the first time that Cdc12p localizes to a broad band of 30-50 dynamic nodes, where actin filaments are nucleated in random directions. The proposed progenitor spot, essential for the spot/leading cable model, usually disappears without nucleating actin filaments. alpha-Actinin ain1 deletion cells form a normal contractile ring through nodes in the absence of the spot. Myosin motor activity is required to condense the nodes into a contractile ring, based on slower or absent node condensation in myo2-E1 and UCS rng3-65 mutants. Taken together, these data provide strong support for the SCPR model of contractile-ring formation in cytokinesis.
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Affiliation(s)
- Valerie C Coffman
- Department of Molecular Genetics, Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210, USA
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