1
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Odfalk KF, Wickline JL, Smith S, Dobrowolski R, Hopp SC. Hippocampal TMEM55B overexpression in the 5XFAD mouse model of Alzheimer's disease. Hippocampus 2024; 34:29-35. [PMID: 37961834 PMCID: PMC10873028 DOI: 10.1002/hipo.23586] [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: 05/31/2023] [Revised: 09/28/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023]
Abstract
Dysfunction of the endosomal-lysosomal network is a notable feature of Alzheimer's disease (AD) pathology. Dysfunctional endo-lysosomal vacuoles accumulate in dystrophic neurites surrounding amyloid β (Aβ) plaques and may be involved in the pathogenesis and progression of Aβ aggregates. Trafficking and thus maturation of these dysfunctional vacuoles is disrupted in the vicinity of Aβ plaques. Transmembrane protein 55B (TMEM55B), also known as phosphatidylinositol-4,5-bisphosphate 4-phosphatase 1 (PIP4P1) is an endo-lysosomal membrane protein that is necessary for appropriate trafficking of endo-lysosomes. The present study tested whether overexpression of TMEM55B in the hippocampus could prevent plaque-associated axonal accumulation of dysfunctional endo-lysosomes, reduce Aβ plaque load, and prevent hippocampal-dependent learning and memory deficits in the 5XFAD mouse models of Aβ plaque pathology. Immunohistochemical analyses revealed a modest but significant reduction in the accumulation of endo-lysosomes in dystrophic neurites surrounding Aβ plaques, but there was no change in hippocampal-dependent memory or plaque load. Overall, these data indicate a potential role for TMEM55B in reducing endo-lysosomal dysfunction during AD-like Aβ pathology.
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Affiliation(s)
- Kristian F. Odfalk
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio
- Department of Pharmacology, University of Texas Health Science Center San Antonio
| | - Jessica L. Wickline
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio
- Department of Pharmacology, University of Texas Health Science Center San Antonio
| | - Sabrina Smith
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio
- Department of Pharmacology, University of Texas Health Science Center San Antonio
| | - Radek Dobrowolski
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio
- Rutgers University
| | - Sarah C. Hopp
- Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio
- Department of Pharmacology, University of Texas Health Science Center San Antonio
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2
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Pal P, Taylor M, Lam PY, Tonelli F, Hecht CA, Lis P, Nirujogi RS, Phung TK, Yeshaw WM, Jaimon E, Fasimoye R, Dickie EA, Wightman M, Macartney T, Pfeffer SR, Alessi DR. Parkinson's VPS35[D620N] mutation induces LRRK2-mediated lysosomal association of RILPL1 and TMEM55B. SCIENCE ADVANCES 2023; 9:eadj1205. [PMID: 38091401 PMCID: PMC10848721 DOI: 10.1126/sciadv.adj1205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/13/2023] [Indexed: 12/18/2023]
Abstract
We demonstrate that the Parkinson's VPS35[D620N] mutation alters the expression of ~220 lysosomal proteins and stimulates recruitment and phosphorylation of Rab proteins at the lysosome. This recruits the phospho-Rab effector protein RILPL1 to the lysosome where it binds to the lysosomal integral membrane protein TMEM55B. We identify highly conserved regions of RILPL1 and TMEM55B that interact and design mutations that block binding. In mouse fibroblasts, brain, and lung, we demonstrate that the VPS35[D620N] mutation reduces RILPL1 levels, in a manner reversed by LRRK2 inhibition and proteasome inhibitors. Knockout of RILPL1 enhances phosphorylation of Rab substrates, and knockout of TMEM55B increases RILPL1 levels. The lysosomotropic agent LLOMe also induced LRRK2 kinase-mediated association of RILPL1 to the lysosome, but to a lower extent than the D620N mutation. Our study uncovers a pathway through which dysfunctional lysosomes resulting from the VPS35[D620N] mutation recruit and activate LRRK2 on the lysosomal surface, driving assembly of the RILPL1-TMEM55B complex.
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Affiliation(s)
- Prosenjit Pal
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Matthew Taylor
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Pui Yiu Lam
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Francesca Tonelli
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Chloe A. Hecht
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
| | - Pawel Lis
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Raja S. Nirujogi
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Toan K. Phung
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Wondwossen M. Yeshaw
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
| | - Ebsy Jaimon
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
| | - Rotimi Fasimoye
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Emily A. Dickie
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Melanie Wightman
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Thomas Macartney
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Suzanne R. Pfeffer
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
| | - Dario R. Alessi
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
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Sasazawa Y, Hattori N, Saiki S. JNK-interacting protein 4 is a central molecule for lysosomal retrograde trafficking. Bioessays 2023; 45:e2300052. [PMID: 37559169 DOI: 10.1002/bies.202300052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/31/2023] [Accepted: 08/02/2023] [Indexed: 08/11/2023]
Abstract
Lysosomal positioning is an important factor in regulating cellular responses, including autophagy. Because proteins encoded by disease-responsible genes are involved in lysosomal trafficking, proper intracellular lysosomal trafficking is thought to be essential for cellular homeostasis. In the past few years, the mechanisms of lysosomal trafficking have been elucidated with a focus on adapter proteins linking motor proteins to lysosomes. Here, we outline recent findings on the mechanisms of lysosomal trafficking by focusing on adapter protein c-Jun NH2 -terminal kinase-interacting protein (JIP) 4, which plays a central role in this process, and other JIP4 functions and JIP family proteins. Additionally, we discuss neuronal diseases associated with aberrance in the JIP family protein. Accumulating evidence suggests that chemical manipulation of lysosomal positioning may be a therapeutic approach for these neuronal diseases.
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Affiliation(s)
- Yukiko Sasazawa
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Neurology, Juntendo University Faculty of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University Faculty of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Shinji Saiki
- Department of Neurology, Juntendo University Faculty of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Neurology, Institute of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
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4
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Rameh LE, Blind RD. 25 Years of PI5P. Front Cell Dev Biol 2023; 11:1272911. [PMID: 37849742 PMCID: PMC10577294 DOI: 10.3389/fcell.2023.1272911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The accidental discovery of PI5P (phosphatidylinositol-5-phosphate) was published 25 years ago, when PIP5K type II (phosphoinositide-4-phosphate 5-kinase) was shown to actually be a 4-kinase that uses PI5P as a substrate to generate PI(4,5)P2. Consequently, PIP5K type II was renamed to PI5P4K, or PIP4K for short, and PI5P became the last of the 7 signaling phosphoinositides to be discovered. Much of what we know about PI5P comes from genetic studies of PIP4K, as the pathways for PI5P synthesis, the downstream targets of PI5P and how PI5P affects cellular function all remain largely enigmatic. Nevertheless, PI5P and PI5P-dependent PI(4,5)P2 synthesis have been clearly implicated in metabolic homeostasis and in diseases such as cancer. Here, we review the past 25 years of PI5P research, with particular emphasis on the impact this small signaling lipid has on human health.
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Affiliation(s)
- Lucia E. Rameh
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Raymond D. Blind
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
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Zeng W, Zhu J, Zeng D, Guo J, Huang G, Zeng Y, Wang L, Bin J, Liao Y, Shi M, Liao W. Epigenetic Modification-Associated Molecular Classification of Gastric Cancer. J Transl Med 2023; 103:100170. [PMID: 37150296 DOI: 10.1016/j.labinv.2023.100170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 04/02/2023] [Accepted: 04/20/2023] [Indexed: 05/09/2023] Open
Abstract
Epigenetic modification is involved in tumorigenesis and cancer progression. We developed an epigenetic modification-associated molecular classification of gastric cancer (GC) to identify signature genes that accurately predict prognosis and the efficacy of immunotherapy. Least absolute shrinkage and selection operator and multivariate Cox regression analysis were conducted to develop an epigenetic modification-associated molecular classification. We investigated the significance of PIP4P2, an independent prognostic factor of the classification system, in predicting the prognosis and immunotherapy efficacy of patients with GC. The epigenetic modification-associated molecular classification was highly associated with the clinicopathological characteristics of patients and the existing classification of GC. PIP4P2 was highly expressed in GC tissue and tumor-associated macrophages. High PIP4P2 expression in GC tissue-induced tumor progression by activating PI3K/AKT signal transduction had a negative impact on immunotherapy efficacy. High expression of PIP4P2 in macrophages was correlated with poor prognosis in patients with GC. PIP4P2 is an independent unfavorable prognostic factor of epigenetic modification-associated molecular classification, is involved in tumorigenic progression, and is essential for assessing the prognosis and immunotherapy efficacy of GC.
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Affiliation(s)
- Wei Zeng
- Department of Oncology, First Peoples Hospital of Shunde, Shunde Hospital of Southern Medical University, Shunde, China; Department of Hematology and Oncology, Shenzhen University General Hospital, Shenzhen University, Shenzhen, China
| | - Jinfeng Zhu
- Department of General Surgery, Shenzhen University General Hospital, Shenzhen University, Shenzhen, China
| | - Dongqiang Zeng
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Jian Guo
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Genjie Huang
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Yu Zeng
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Ling Wang
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Jianping Bin
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yulin Liao
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Min Shi
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China
| | - Wangjun Liao
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Province Key Laboratory of Molecular Tumor Pathology, Southern Medical University, Guangzhou, China.
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6
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Abstract
Phosphoinositides (PIs) are phospholipids derived from phosphatidylinositol. PIs are regulated via reversible phosphorylation, which is directed by the opposing actions of PI kinases and phosphatases. PIs constitute a minor fraction of the total cellular lipid pool but play pleiotropic roles in multiple aspects of cell biology. Genetic mutations of PI regulatory enzymes have been identified in rare congenital developmental syndromes, including ciliopathies, and in numerous human diseases, such as cancer and metabolic and neurological disorders. Accordingly, PI regulatory enzymes have been targeted in the design of potential therapeutic interventions for human diseases. Recent advances place PIs as central regulators of membrane dynamics within functionally distinct subcellular compartments. This brief review focuses on the emerging role PIs play in regulating cell signaling within the primary cilium and in directing transfer of molecules at interorganelle membrane contact sites and identifies new roles for PIs in subcellular spaces.
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Affiliation(s)
- Elizabeth Michele Davies
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Christina Anne Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Harald Alfred Stenmark
- Department of Molecular Cell Biology, Institute for Cancer Research. The Norwegian Radium Hospital, Montebello, N-0379 Oslo, Norway
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Montebello, N-0379 Oslo, Norway
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7
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Wen T, Thapa N, Cryns VL, Anderson RA. Regulation of Phosphoinositide Signaling by Scaffolds at Cytoplasmic Membranes. Biomolecules 2023; 13:1297. [PMID: 37759697 PMCID: PMC10526805 DOI: 10.3390/biom13091297] [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: 08/01/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023] Open
Abstract
Cytoplasmic phosphoinositides (PI) are critical regulators of the membrane-cytosol interface that control a myriad of cellular functions despite their low abundance among phospholipids. The metabolic cycle that generates different PI species is crucial to their regulatory role, controlling membrane dynamics, vesicular trafficking, signal transduction, and other key cellular events. The synthesis of phosphatidylinositol (3,4,5)-triphosphate (PI3,4,5P3) in the cytoplamic PI3K/Akt pathway is central to the life and death of a cell. This review will focus on the emerging evidence that scaffold proteins regulate the PI3K/Akt pathway in distinct membrane structures in response to diverse stimuli, challenging the belief that the plasma membrane is the predominant site for PI3k/Akt signaling. In addition, we will discuss how PIs regulate the recruitment of specific scaffolding complexes to membrane structures to coordinate vesicle formation, fusion, and reformation during autophagy as well as a novel lysosome repair pathway.
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Affiliation(s)
- Tianmu Wen
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA; (T.W.); (N.T.)
| | - Narendra Thapa
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA; (T.W.); (N.T.)
| | - Vincent L. Cryns
- Department of Medicine, University of Wisconsin Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Richard A. Anderson
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA; (T.W.); (N.T.)
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8
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Vidalle MC, Sheth B, Fazio A, Marvi MV, Leto S, Koufi FD, Neri I, Casalin I, Ramazzotti G, Follo MY, Ratti S, Manzoli L, Gehlot S, Divecha N, Fiume R. Nuclear Phosphoinositides as Key Determinants of Nuclear Functions. Biomolecules 2023; 13:1049. [PMID: 37509085 PMCID: PMC10377365 DOI: 10.3390/biom13071049] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Polyphosphoinositides (PPIns) are signalling messengers representing less than five per cent of the total phospholipid concentration within the cell. Despite their low concentration, these lipids are critical regulators of various cellular processes, including cell cycle, differentiation, gene transcription, apoptosis and motility. PPIns are generated by the phosphorylation of the inositol head group of phosphatidylinositol (PtdIns). Different pools of PPIns are found at distinct subcellular compartments, which are regulated by an array of kinases, phosphatases and phospholipases. Six of the seven PPIns species have been found in the nucleus, including the nuclear envelope, the nucleoplasm and the nucleolus. The identification and characterisation of PPIns interactor and effector proteins in the nucleus have led to increasing interest in the role of PPIns in nuclear signalling. However, the regulation and functions of PPIns in the nucleus are complex and are still being elucidated. This review summarises our current understanding of the localisation, biogenesis and physiological functions of the different PPIns species in the nucleus.
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Affiliation(s)
- Magdalena C Vidalle
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Bhavwanti Sheth
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Antonietta Fazio
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Maria Vittoria Marvi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Leto
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Foteini-Dionysia Koufi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Neri
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Casalin
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Giulia Ramazzotti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Matilde Y Follo
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Ratti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Lucia Manzoli
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Sonakshi Gehlot
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Nullin Divecha
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Roberta Fiume
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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Du Y, Chang W, Gao L, Deng L, Ji WK. Tex2 is required for lysosomal functions at TMEM55-dependent ER membrane contact sites. J Cell Biol 2023; 222:213838. [PMID: 36705603 PMCID: PMC9930140 DOI: 10.1083/jcb.202205133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 10/17/2022] [Accepted: 01/05/2023] [Indexed: 01/28/2023] Open
Abstract
ER tubules form and maintain membrane contact sites (MCSs) with late endosomes/lysosomes (LE/lys). The molecular composition and cellular functions of these MCSs are poorly understood. Here, we find that Tex2, an SMP domain-containing lipid transfer protein conserved in metazoan and yeast, is a tubular ER protein and is recruited to ER-LE/lys MCSs by TMEM55, phosphatases that convert PI(4,5)P2 to PI5P on LE/lys. We show that the Tex2-TMEM55 interaction occurs between an N-terminal region of Tex2 and a catalytic motif in the PTase domain of TMEM55. The Tex2-TMEM55 interaction can be regulated by endosome-resident type 2 PI4K activities. Functionally, Tex2 knockout results in defects in lysosomal trafficking, digestive capacity, and lipid composition of LE/lys membranes. Together, our data identify Tex2 as a tubular ER protein that resides at TMEM55-dependent ER-LE/lys MCSs required for lysosomal functions.
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Affiliation(s)
- Yuanjiao Du
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Wuhan, China,https://ror.org/00p991c53Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China,https://ror.org/00sdcjz77Shenzhen Bay Laboratory, Shenzhen, China
| | - Weiping Chang
- https://ror.org/00sdcjz77Shenzhen Bay Laboratory, Shenzhen, China
| | - Lei Gao
- https://ror.org/05hfa4n20Microscopy Core Facility, Westlake University, Hangzhou, Zhejiang, China
| | - Lin Deng
- https://ror.org/00sdcjz77Shenzhen Bay Laboratory, Shenzhen, China
| | - Wei-Ke Ji
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Wuhan, China,https://ror.org/00p991c53Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China,https://ror.org/00sdcjz77Shenzhen Bay Laboratory, Shenzhen, China,Correspondence to Wei-Ke Ji:
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10
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Qin Y, Medina MW. Mechanism of the Regulation of Plasma Cholesterol Levels by PI(4,5)P 2. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:89-119. [PMID: 36988878 DOI: 10.1007/978-3-031-21547-6_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Elevated low-density lipoprotein (LDL) cholesterol (LDLc) is one of the most well-established risk factors for cardiovascular disease, while high levels of high-density lipoprotein (HDL) cholesterol (HDLc) have been associated with protection from cardiovascular disease. Cardiovascular disease remains one of the leading causes of death worldwide; thus it is important to understand mechanisms that impact LDLc and HDLc metabolism. In this chapter, we will discuss molecular processes by which phosphatidylinositol-(4,5)-bisphosphate, PI(4,5)P2, is thought to modulate LDLc or HDLc. Section 1 will provide an overview of cholesterol in the circulation, discussing processes that modulate the various forms of lipoproteins (LDL and HDL) carrying cholesterol. Section 2 will describe how a PI(4,5)P2 phosphatase, transmembrane protein 55B (TMEM55B), impacts circulating LDLc levels through its ability to regulate lysosomal decay of the low-density lipoprotein receptor (LDLR), the primary receptor for hepatic LDL uptake. Section 3 will discuss how PI(4,5)P2 interacts with apolipoprotein A-I (apoA1), the key apolipoprotein on HDL. In addition to direct mechanisms of PI(4,5)P2 action on circulating cholesterol, Sect. 4 will review how PI(4,5)P2 may indirectly impact LDLc and HDLc by affecting insulin action. Last, as cholesterol is controlled through intricate negative feedback loops, Sect. 5 will describe how PI(4,5)P2 is regulated by cholesterol.
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Affiliation(s)
- Yuanyuan Qin
- Department of Pediatrics, Division of Cardiology, University of California, San Francisco, Oakland, CA, USA
| | - Marisa W Medina
- Department of Pediatrics, Division of Cardiology, University of California, San Francisco, Oakland, CA, USA.
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11
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Enrich C, Lu A, Tebar F, Rentero C, Grewal T. Ca 2+ and Annexins - Emerging Players for Sensing and Transferring Cholesterol and Phosphoinositides via Membrane Contact Sites. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:393-438. [PMID: 36988890 DOI: 10.1007/978-3-031-21547-6_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Maintaining lipid composition diversity in membranes from different organelles is critical for numerous cellular processes. However, many lipids are synthesized in the endoplasmic reticulum (ER) and require delivery to other organelles. In this scenario, formation of membrane contact sites (MCS) between neighbouring organelles has emerged as a novel non-vesicular lipid transport mechanism. Dissecting the molecular composition of MCS identified phosphoinositides (PIs), cholesterol, scaffolding/tethering proteins as well as Ca2+ and Ca2+-binding proteins contributing to MCS functioning. Compelling evidence now exists for the shuttling of PIs and cholesterol across MCS, affecting their concentrations in distinct membrane domains and diverse roles in membrane trafficking. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) at the plasma membrane (PM) not only controls endo-/exocytic membrane dynamics but is also critical in autophagy. Cholesterol is highly concentrated at the PM and enriched in recycling endosomes and Golgi membranes. MCS-mediated cholesterol transfer is intensely researched, identifying MCS dysfunction or altered MCS partnerships to correlate with de-regulated cellular cholesterol homeostasis and pathologies. Annexins, a conserved family of Ca2+-dependent phospholipid binding proteins, contribute to tethering and untethering events at MCS. In this chapter, we will discuss how Ca2+ homeostasis and annexins in the endocytic compartment affect the sensing and transfer of cholesterol and PIs across MCS.
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Affiliation(s)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.
| | - Albert Lu
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel⋅lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
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12
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Rajala A, Rajala R, Teel K, Rajala RVS. Ribosomal targeting strategy and nuclear labeling to analyze photoreceptor phosphoinositide signatures. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159161. [PMID: 35427794 PMCID: PMC10812878 DOI: 10.1016/j.bbalip.2022.159161] [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: 02/02/2022] [Revised: 04/03/2022] [Accepted: 04/08/2022] [Indexed: 10/18/2022]
Abstract
Reversible phosphorylation of phosphatidylinositol by phosphoinositide (PI) kinases and phosphatases generates seven distinct phosphoinositide phosphates, called phosphoinositides or PIPs. All seven PIPs are formed in the retina and photoreceptor cells. Around 50 genes in the mammalian genome encode PI kinases and PI phosphatases. There are no studies available on the distribution of these enzymes in the retina and photoreceptors. AIM To employ Ribosomal Targeting Strategy and Nuclear Labeling to Analyze Phosphoinositide Signatures in rod-photoreceptor cells. METHODS HA-tagging of ribosomal protein Rpl22 was induced with Cre-recombinase under the control of the rhodopsin promoter. Actively translating mRNAs associated with polyribosomes were isolated by immunoprecipitation with HA antibody, followed by RNA isolation and gene identification. We also isolated biotinylated-rod nuclei from NuTRAP mice under the control of the rhodopsin-Cre promoter and analyzed nuclear phosphoinositides. RESULTS Our results indicate that the expression of class I and class III PI 3-kinase, PI4K IIIβ, PI 5-kinase, PIKfyve, PI3-phosphatases, MTMR2, 4, 6, 7, 14, PI4-phosphatase, TMEM55A, PI 5-phosphatases, SYNJI, INPP5B, INPP5E, INPP5F, SKIP and other phosphatases with dual substrate specificity, PTPMT1, SCAM1, and FIG4 are highly enriched in rod photoreceptor cells compared with the retina and cone-like retina. Our analysis identified the presence of PI(4)P, PI(3,4)P2, PI(3,5)P2, and PI(4,5)P2 in the rod nuclei. CONCLUSIONS Our studies for the first time demonstrate the expression of PI kinases, PI phosphatases, and nuclear PIPs in rod photoreceptor cells. The NuTRAP mice may be useful not only for epigenetic and transcriptomic studies but also for in vivo cell-specific lipidomics research.
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Affiliation(s)
- Ammaji Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean McGee Eye Institute, Oklahoma City, OK 73014, USA
| | - Rahul Rajala
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73014, USA
| | - Kenneth Teel
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean McGee Eye Institute, Oklahoma City, OK 73014, USA
| | - Raju V S Rajala
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean McGee Eye Institute, Oklahoma City, OK 73014, USA.
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13
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Ceyhan Y, Zhang M, Sandoval CG, Agoulnik AI, Agoulnik IU. Expression pattern and the roles of phosphatidylinositol phosphatases in testis. Biol Reprod 2022; 107:902-915. [PMID: 35766372 DOI: 10.1093/biolre/ioac132] [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: 03/23/2022] [Revised: 06/02/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphoinositides (PIs) are relatively rare lipid components of the cellular membranes. Their homeostasis is tightly controlled by specific PI kinases and phosphatases. PIs play essential roles in cellular signaling, cytoskeletal organization, and secretory processes in various diseases and normal physiology. Gene targeting experiments strongly suggest that in mice with deficiency of several PI phosphatases such as Pten, Mtmrs, Inpp4b, and Inpp5b, spermatogenesis is affected, resulting in partial or complete infertility. Similarly, in men, loss of several of the PIP phosphatases is observed in infertility characterized by the lack of mature sperm. Using available gene expression databases, we compare expression of known PI phosphatases in various testicular cell types, infertility patients, and mouse age-dependent testicular gene expression, and discuss their potential roles in testis physiology and spermatogenesis.
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Affiliation(s)
- Yasemin Ceyhan
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Manqi Zhang
- Department of Medicine, Duke University, Durham, NC, USA
| | - Carlos G Sandoval
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,New York University Grossman School of Medicine, New York, NY, USA
| | - Alexander I Agoulnik
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Irina U Agoulnik
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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14
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Wang YH, Sheetz MP. When PIP 2 Meets p53: Nuclear Phosphoinositide Signaling in the DNA Damage Response. Front Cell Dev Biol 2022; 10:903994. [PMID: 35646908 PMCID: PMC9136457 DOI: 10.3389/fcell.2022.903994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms that maintain genome stability are critical for preventing tumor progression. In the past decades, many strategies were developed for cancer treatment to disrupt the DNA repair machinery or alter repair pathway selection. Evidence indicates that alterations in nuclear phosphoinositide lipids occur rapidly in response to genotoxic stresses. This implies that nuclear phosphoinositides are an upstream element involved in DNA damage signaling. Phosphoinositides constitute a new signaling interface for DNA repair pathway selection and hence a new opportunity for developing cancer treatment strategies. However, our understanding of the underlying mechanisms by which nuclear phosphoinositides regulate DNA damage repair, and particularly the dynamics of those processes, is rather limited. This is partly because there are a limited number of techniques that can monitor changes in the location and/or abundance of nuclear phosphoinositide lipids in real time and in live cells. This review summarizes our current knowledge regarding the roles of nuclear phosphoinositides in DNA damage response with an emphasis on the dynamics of these processes. Based upon recent findings, there is a novel model for p53's role with nuclear phosphoinositides in DNA damage response that provides new targets for synthetic lethality of tumors.
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Affiliation(s)
| | - Michael P. Sheetz
- Biochemistry and Molecular Biology Dept., University of Texas Medical Branch, Galveston, TX, United States
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15
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Rudnik S, Heybrock S, Saftig P, Damme M. S-palmitoylation determines TMEM55B-dependent positioning of lysosomes. J Cell Sci 2022; 135:jcs258566. [PMID: 34350967 DOI: 10.1242/jcs.258566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 07/23/2021] [Indexed: 11/20/2022] Open
Abstract
The spatiotemporal cellular distribution of lysosomes depends on active transport mainly driven by microtubule motors such as kinesins and dynein. Different protein complexes attach these molecular motors to their vesicular cargo. TMEM55B (also known as PIP4P1), as an integral lysosomal membrane protein, is a component of such a complex that mediates the retrograde transport of lysosomes by establishing interactions with the cytosolic scaffold protein JIP4 (also known as SPAG9) and dynein-dynactin. Here, we show that TMEM55B and its paralog TMEM55A (PIP4P2) are S-palmitoylated proteins that are lipidated at multiple cysteine residues. Mutation of all cysteines in TMEM55B prevents S-palmitoylation and causes retention of the mutated protein in the Golgi. Consequently, non-palmitoylated TMEM55B is no longer able to modulate lysosomal positioning and the perinuclear clustering of lysosomes. Additional mutagenesis of the dileucine-based lysosomal sorting motif in non-palmitoylated TMEM55B leads to partial missorting to the plasma membrane instead of retention in the Golgi, implicating a direct effect of S-palmitoylation on the adaptor protein-dependent sorting of TMEM55B. Our data suggest a critical role for S-palmitoylation in the trafficking of TMEM55B and TMEM55B-dependent lysosomal positioning.
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Affiliation(s)
- Sönke Rudnik
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Saskia Heybrock
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Paul Saftig
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Markus Damme
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
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16
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Tariq K, Luikart BW. Striking a balance: PIP 2 and PIP 3 signaling in neuronal health and disease. EXPLORATION OF NEUROPROTECTIVE THERAPY 2022; 1:86-100. [PMID: 35098253 PMCID: PMC8797975 DOI: 10.37349/ent.2021.00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phosphoinositides are membrane phospholipids involved in a variety of cellular processes like growth, development, metabolism, and transport. This review focuses on the maintenance of cellular homeostasis of phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidylinositol 3,4,5-trisphosphate (PIP3). The critical balance of these PIPs is crucial for regulation of neuronal form and function. The activity of PIP2 and PIP3 can be regulated through kinases, phosphatases, phospholipases and cholesterol microdomains. PIP2 and PIP3 carry out their functions either indirectly through their effectors activating integral signaling pathways, or through direct regulation of membrane channels, transporters, and cytoskeletal proteins. Any perturbations to the balance between PIP2 and PIP3 signaling result in neurodevelopmental and neurodegenerative disorders. This review will discuss the upstream modulators and downstream effectors of the PIP2 and PIP3 signaling, in the context of neuronal health and disease.
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Affiliation(s)
- Kamran Tariq
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Bryan W Luikart
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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17
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Akhtar BM, Bhatia P, Acharya S, Sharma S, Sharma Y, Aswathy BS, Ganapathy K, Vasudevan A, Raghu P. A human stem cell resource to decipher the biochemical and cellular basis of neurodevelopmental defects in Lowe Syndrome. Biol Open 2022; 11:274000. [PMID: 35023542 PMCID: PMC8822356 DOI: 10.1242/bio.059066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 12/14/2021] [Indexed: 11/20/2022] Open
Abstract
Human brain development is a complex process where multiple cellular and developmental events are coordinated to generate normal structure and function. Alteration in any of these events can impact brain development, manifesting clinically as neurodevelopmental disorders. Human genetic disorders of lipid metabolism often present with features of altered brain function. Lowe syndrome (LS) is an X-linked recessive disease with features of altered brain function. LS results from mutations in OCRL1, which encodes a phosphoinositide 5-phosphatase enzyme. However, the cellular mechanisms by which loss of OCRL1 leads to brain defects remain unknown. Human brain development involves several cellular and developmental features not conserved in other species and understanding such mechanisms remains a challenge. Rodent models of LS have been generated but failed to recapitulate features of the human disease. Here we describe the generation of human stem cell lines from LS patients. Further, we present biochemical characterization of lipid metabolism in patient cell lines and demonstrate their use as a ‘disease-in-a-dish’ model for understanding the mechanism by which loss of OCRL1 leads to altered cellular and physiological brain development. This article has an associated First Person interview with the first author of the paper. Summary: A human iPSC resource to study the cellular basis of neurodevelopmental defects in Lowe syndrome.
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Affiliation(s)
- Bilal M Akhtar
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bengaluru-560065, India
| | - Priyanka Bhatia
- Brain Development and Disease Mechanisms, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru-560065, India
| | - Shubhra Acharya
- Brain Development and Disease Mechanisms, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru-560065, India
| | - Sanjeev Sharma
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bengaluru-560065, India
| | - Yojet Sharma
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bengaluru-560065, India
| | - B S Aswathy
- Brain Development and Disease Mechanisms, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru-560065, India
| | - Kavina Ganapathy
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bengaluru-560065, India.,Department of Biotechnology, Center for Post Graduate Studies, School of Sciences, Jain University, Bangalore-560027, India
| | - Anil Vasudevan
- Department of Pediatric Nephrology, St. John's Medical College Hospital, Bengaluru-560034, India
| | - Padinjat Raghu
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bengaluru-560065, India.,Brain Development and Disease Mechanisms, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru-560065, India
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18
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Transcriptome analysis of Kentucky bluegrass subject to drought and ethephon treatment. PLoS One 2021; 16:e0261472. [PMID: 34914788 PMCID: PMC8675742 DOI: 10.1371/journal.pone.0261472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 12/03/2021] [Indexed: 11/19/2022] Open
Abstract
Kentucky bluegrass (Poa pratensis L.) is an excellent cool-season turfgrass utilized widely in Northern China. However, turf quality of Kentucky bluegrass declines significantly due to drought. Ethephon seeds-soaking treatment has been proved to effectively improve the drought tolerance of Kentucky bluegrass seedlings. In order to investigate the effect of ethephon leaf-spraying method on drought tolerance of Kentucky bluegrass and understand the underlying mechanism, Kentucky bluegrass plants sprayed with and without ethephon are subjected to either drought or well watered treatments. The relative water content and malondialdehyde conent were measured. Meanwhile, samples were sequenced through Illumina. Results showed that ethephon could improve the drought tolerance of Kentucky bluegrass by elevating relative water content and decreasing malondialdehyde content under drought. Transcriptome analysis showed that 58.43% transcripts (254,331 out of 435,250) were detected as unigenes. A total of 9.69% (24,643 out of 254,331) unigenes were identified as differentially expressed genes in one or more of the pairwise comparisons. Differentially expressed genes due to drought stress with or without ethephon pre-treatment showed that ethephon application affected genes associated with plant hormone, signal transduction pathway and plant defense, protein degradation and stabilization, transportation and osmosis, antioxidant system and the glyoxalase pathway, cell wall and cuticular wax, fatty acid unsaturation and photosynthesis. This study provides a theoretical basis for revealing the mechanism for how ethephon regulates drought response and improves drought tolerance of Kentucky bluegrass.
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19
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Gu J, Geng M, Qi M, Wang L, Zhang Y, Gao J. The role of lysosomal membrane proteins in glucose and lipid metabolism. FASEB J 2021; 35:e21848. [PMID: 34582051 DOI: 10.1096/fj.202002602r] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/11/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022]
Abstract
Lysosomes have long been regarded as the "garbage dump" of the cell. More recently, however, researchers have revealed novel roles for lysosomal membranes in autophagy, ion transport, nutrition sensing, and membrane fusion and repair. With active research into lysosomal membrane proteins (LMP), increasing evidence has become available showing that LMPs are inextricably linked to glucose and lipid metabolism, and this relationship represents mutual influence and regulation. In this review, we summarize the roles of LMPs in relation to glucose and lipid metabolism, and describe their roles in glucose transport, glycolysis, cholesterol transport, and lipophagy. The role of transport proteins can be traced back to the original discoveries of GLUT8, NPC1, and NPC2, which were all found to have significant roles in the pathways involved in glucose and lipid metabolism. CLC-5 and SIDT2-knockout animals show serious phenotypic disorders of metabolism, and V-ATPase and LAMP-2 have been found to interact with proteins related to glucose and lipid metabolism. These findings all emphasize the critical role of LMPs in glycolipid metabolism and help to strengthen our understanding of the independent and close relationship between LMPs and glycolipid metabolism.
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Affiliation(s)
- Jing Gu
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
| | - Mengya Geng
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Mengxiang Qi
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Jialin Gao
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
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20
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Araki M, Kontani K. Regulation of lysosomal positioning via TMEM55B phosphorylation. J Biochem 2021; 169:507-509. [PMID: 33537719 DOI: 10.1093/jb/mvab013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 12/30/2020] [Indexed: 01/15/2023] Open
Abstract
Lysosomes are dynamic organelles that are transported along microtubules bidirectionally via kinesin and dynein motor proteins. Lysosomal positioning, which is determined by the balance of the bidirectional lysosomal movement, changes under various conditions and affects lysosomal functions such as autophagy and antigen presentation. A recent study by Takemasu et al. (Phosphorylation of TMEM55B by Erk/MAPK regulates lysosomal positioning. J. Biochem. 2019; 166:175-185) has shown that phosphorylation of the transmembrane protein TMEM55B is involved in the retrograde lysosomal trafficking towards the perinuclear region. They found that TMEM55B is phosphorylated upon stimulation with various ligands and that Erk/MAPK mediates the TMEM55B phosphorylation. They have also revealed that a phosphorylation mimic mutant of TMEM55B enhances perinuclear lysosomal clustering compared to the wild-type TMEM55B. These findings suggest that TMEM55B phosphorylation by Erk/MAPK is responsible for regulating lysosomal positioning in response to external stimuli.
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Affiliation(s)
- Makoto Araki
- Department of Biochemistry, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Kenji Kontani
- Department of Biochemistry, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
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21
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Qin Y, Ting F, Kim MJ, Strelnikov J, Harmon J, Gao F, Dose A, Teng BB, Alipour MA, Yao Z, Crooke R, Krauss RM, Medina MW. Phosphatidylinositol-(4,5)-Bisphosphate Regulates Plasma Cholesterol Through LDL (Low-Density Lipoprotein) Receptor Lysosomal Degradation. Arterioscler Thromb Vasc Biol 2020; 40:1311-1324. [PMID: 32188273 DOI: 10.1161/atvbaha.120.314033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE TMEM55B (transmembrane protein 55B) is a phosphatidylinositol-(4,5)-bisphosphate (PI[4,5]P2) phosphatase that regulates cellular cholesterol, modulates LDLR (low-density lipoprotein receptor) decay, and lysosome function. We tested the effects of Tmem55b knockdown on plasma lipids in mice and assessed the roles of LDLR lysosomal degradation and change in (PI[4,5]P2) in mediating these effects. Approach and Results: Western diet-fed C57BL/6J mice were treated with antisense oligonucleotides against Tmem55b or a nontargeting control for 3 to 4 weeks. Hepatic Tmem55b transcript and protein levels were reduced by ≈70%, and plasma non-HDL (high-density lipoprotein) cholesterol was increased ≈1.8-fold (P<0.0001). Immunoblot analysis of fast protein liquid chromatography (FPLC) fractions revealed enrichment of ApoE-containing particles in the LDL size range. In contrast, Tmem55b knockdown had no effect on plasma cholesterol in Ldlr-/- mice. In primary hepatocytes and liver tissues from Tmem55b knockdown mice, there was decreased LDLR protein. In the hepatocytes, there was increased lysosome staining and increased LDLR-lysosome colocalization. Impairment of lysosome function (incubation with NH4Cl or knockdown of the lysosomal proteins LAMP1 or RAB7) abolished the effect of TMEM55B knockdown on LDLR in HepG2 (human hepatoma) cells. Colocalization of the recycling endosome marker RAB11 (Ras-related protein 11) with LDLR in HepG2 cells was reduced by 50% upon TMEM55B knockdown. Finally, knockdown increased hepatic PI(4,5)P2 levels in vivo and in HepG2 cells, while TMEM55B overexpression in vitro decreased PI(4,5)P2. TMEM55B knockdown decreased, whereas overexpression increased, LDL uptake in HepG2 cells. Notably, the TMEM55B overexpression effect was reversed by incubation with PI(4,5)P2. Conclusions: These findings indicate a role for TMEM55B in regulating plasma cholesterol levels by affecting PI(4,5)P2-mediated LDLR lysosomal degradation.
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Affiliation(s)
- Yuanyuan Qin
- From the Department of Pediatrics, University of California San Francisco, Oakland (Y.Q., F.T., R.M.K., M.W.M.)
| | - Flora Ting
- From the Department of Pediatrics, University of California San Francisco, Oakland (Y.Q., F.T., R.M.K., M.W.M.)
| | - Mee J Kim
- Children's Hospital Oakland Research Institute, CA (M.J.K., J.S., J.H., F.G., A.D.)
| | - Jacob Strelnikov
- Children's Hospital Oakland Research Institute, CA (M.J.K., J.S., J.H., F.G., A.D.)
| | - Joseph Harmon
- Children's Hospital Oakland Research Institute, CA (M.J.K., J.S., J.H., F.G., A.D.)
| | - Feng Gao
- Children's Hospital Oakland Research Institute, CA (M.J.K., J.S., J.H., F.G., A.D.)
| | - Andrea Dose
- Children's Hospital Oakland Research Institute, CA (M.J.K., J.S., J.H., F.G., A.D.)
| | - Ba-Bie Teng
- Center for Human Genetics, University of Texas Health Science Center, Houston (B.-B.T.)
| | - Mohsen Amir Alipour
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | | | - Ronald M Krauss
- From the Department of Pediatrics, University of California San Francisco, Oakland (Y.Q., F.T., R.M.K., M.W.M.)
| | - Marisa W Medina
- From the Department of Pediatrics, University of California San Francisco, Oakland (Y.Q., F.T., R.M.K., M.W.M.)
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22
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The Role of Membrane Surface Charge in Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1246:43-54. [DOI: 10.1007/978-3-030-40406-2_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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23
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Ruckert MT, de Andrade PV, Santos VS, Silveira VS. Protein tyrosine phosphatases: promising targets in pancreatic ductal adenocarcinoma. Cell Mol Life Sci 2019; 76:2571-2592. [PMID: 30982078 PMCID: PMC11105579 DOI: 10.1007/s00018-019-03095-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 03/25/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. It is the fourth leading cause of cancer-related death and is associated with a very poor prognosis. KRAS driver mutations occur in approximately 95% of PDAC cases and cause the activation of several signaling pathways such as mitogen-activated protein kinase (MAPK) pathways. Regulation of these signaling pathways is orchestrated by feedback loops mediated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), leading to activation or inhibition of its downstream targets. The human PTPome comprises 125 members, and these proteins are classified into three distinct families according to their structure. Since PTP activity description, it has become clear that they have both inhibitory and stimulatory effects on cancer-associated signaling processes and that deregulation of PTP function is closely associated with tumorigenesis. Several PTPs have displayed either tumor suppressor or oncogenic characteristics during the development and progression of PDAC. In this sense, PTPs have been presented as promising candidates for the treatment of human pancreatic cancer, and many PTP inhibitors have been developed since these proteins were first associated with cancer. Nevertheless, some challenges persist regarding the development of effective and safe methods to target these molecules and deliver these drugs. In this review, we discuss the role of PTPs in tumorigenesis as tumor suppressor and oncogenic proteins. We have focused on the differential expression of these proteins in PDAC, as well as their clinical implications and possible targeting for pharmacological inhibition in cancer therapy.
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Affiliation(s)
- Mariana Tannús Ruckert
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, São Paulo, Brazil
| | - Pamela Viani de Andrade
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, São Paulo, Brazil
| | - Verena Silva Santos
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, São Paulo, Brazil
| | - Vanessa Silva Silveira
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, São Paulo, Brazil.
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Castro-Sánchez P, Aguilar-Sopeña O, Alegre-Gómez S, Ramirez-Munoz R, Roda-Navarro P. Regulation of CD4 + T Cell Signaling and Immunological Synapse by Protein Tyrosine Phosphatases: Molecular Mechanisms in Autoimmunity. Front Immunol 2019; 10:1447. [PMID: 31297117 PMCID: PMC6607956 DOI: 10.3389/fimmu.2019.01447] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/10/2019] [Indexed: 12/13/2022] Open
Abstract
T cell activation and effector function is mediated by the formation of a long-lasting interaction established between T cells and antigen-presenting cells (APCs) called immunological synapse (IS). During T cell activation, different signaling molecules as well as the cytoskeleton and the endosomal compartment are polarized to the IS. This molecular dynamics is tightly regulated by phosphorylation networks, which are controlled by protein tyrosine phosphatases (PTPs). While some PTPs are known to be important regulators of adhesion, ligand discrimination or the stimulation threshold, there is still little information about the regulatory role of PTPs in cytoskeleton rearrangements and endosomal compartment dynamics. Besides, spatial and temporal regulation of PTPs and substrates at the IS is only barely known. Consistent with an important role of PTPs in T cell activation, multiple mutations as well as altered expression levels or dynamic behaviors have been associated with autoimmune diseases. However, the precise mechanism for the regulation of T cell activation and effector function by PTPs in health and autoimmunity is not fully understood. Herein, we review the current knowledge about the regulatory role of PTPs in CD4+ T cell activation, IS assembly and effector function. The potential molecular mechanisms mediating the action of these enzymes in autoimmune disorders are discussed.
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Affiliation(s)
- Patricia Castro-Sánchez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Oscar Aguilar-Sopeña
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Sergio Alegre-Gómez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Rocio Ramirez-Munoz
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Pedro Roda-Navarro
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
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25
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Nakada-Tsukui K, Watanabe N, Maehama T, Nozaki T. Phosphatidylinositol Kinases and Phosphatases in Entamoeba histolytica. Front Cell Infect Microbiol 2019; 9:150. [PMID: 31245297 PMCID: PMC6563779 DOI: 10.3389/fcimb.2019.00150] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PtdIns) metabolism is indispensable in eukaryotes. Phosphoinositides (PIs) are phosphorylated derivatives of PtdIns and consist of seven species generated by reversible phosphorylation of the inositol moieties at the positions 3, 4, and 5. Each of the seven PIs has a unique subcellular and membrane domain distribution. In the enteric protozoan parasite Entamoeba histolytica, it has been previously shown that the PIs phosphatidylinositol 3-phosphate (PtdIns3P), PtdIns(4,5)P2, and PtdIns(3,4,5)P3 are localized to phagosomes/phagocytic cups, plasma membrane, and phagocytic cups, respectively. The localization of these PIs in E. histolytica is similar to that in mammalian cells, suggesting that PIs have orthologous functions in E. histolytica. In contrast, the conservation of the enzymes that metabolize PIs in this organism has not been well-documented. In this review, we summarized the full repertoire of the PI kinases and PI phosphatases found in E. histolytica via a genome-wide survey of the current genomic information. E. histolytica appears to have 10 PI kinases and 23 PI phosphatases. It has a panel of evolutionarily conserved enzymes that generate all the seven PI species. However, class II PI 3-kinases, type II PI 4-kinases, type III PI 5-phosphatases, and PI 4P-specific phosphatases are not present. Additionally, regulatory subunits of class I PI 3-kinases and type III PI 4-kinases have not been identified. Instead, homologs of class I PI 3-kinases and PTEN, a PI 3-phosphatase, exist as multiple isoforms, which likely reflects that elaborate signaling cascades mediated by PtdIns(3,4,5)P3 are present in this organism. There are several enzymes that have the nuclear localization signal: one phosphatidylinositol phosphate (PIP) kinase, two PI 3-phosphatases, and one PI 5-phosphatase; this suggests that PI metabolism also has conserved roles related to nuclear functions in E. histolytica, as it does in model organisms.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Natsuki Watanabe
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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26
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Phosphatidylinositol 5 Phosphate (PI5P): From Behind the Scenes to the Front (Nuclear) Stage. Int J Mol Sci 2019; 20:ijms20092080. [PMID: 31035587 PMCID: PMC6539119 DOI: 10.3390/ijms20092080] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/20/2019] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PI)-related signaling plays a pivotal role in many cellular aspects, including survival, cell proliferation, differentiation, DNA damage, and trafficking. PI is the core of a network of proteins represented by kinases, phosphatases, and lipases which are able to add, remove or hydrolyze PI, leading to different phosphoinositide products. Among the seven known phosphoinositides, phosphatidylinositol 5 phosphate (PI5P) was the last to be discovered. PI5P presence in cells is very low compared to other PIs. However, much evidence collected throughout the years has described the role of this mono-phosphoinositide in cell cycles, stress response, T-cell activation, and chromatin remodeling. Interestingly, PI5P has been found in different cellular compartments, including the nucleus. Here, we will review the nuclear role of PI5P, describing how it is synthesized and regulated, and how changes in the levels of this rare phosphoinositide can lead to different nuclear outputs.
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27
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Gawden-Bone CM, Griffiths GM. Phospholipids: Pulling Back the Actin Curtain for Granule Delivery to the Immune Synapse. Front Immunol 2019; 10:700. [PMID: 31031745 PMCID: PMC6470250 DOI: 10.3389/fimmu.2019.00700] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/14/2019] [Indexed: 12/29/2022] Open
Abstract
Phosphoinositides, together with the phospholipids phosphatidylserine and phosphatidic acid, are important components of the plasma membrane acting as second messengers that, with diacylglycerol, regulate a diverse range of signaling events converting extracellular changes into cellular responses. Local changes in their distribution and membrane charge on the inner leaflet of the plasma membrane play important roles in immune cell function. Here we discuss their distribution and regulators highlighting the importance of membrane changes across the immune synapse on the cytoskeleton and the impact on the function of cytotoxic T lymphocytes.
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Affiliation(s)
| | - Gillian M Griffiths
- Cambridge Institute of Medical Research, University of Cambridge, Cambridge, United Kingdom
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Takemasu S, Nigorikawa K, Yamada M, Tsurumi G, Kofuji S, Takasuga S, Hazeki K. Phosphorylation of TMEM55B by Erk/MAPK regulates lysosomal positioning. J Biochem 2019; 166:175-185. [DOI: 10.1093/jb/mvz026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 04/05/2019] [Indexed: 12/16/2022] Open
Abstract
Abstract
TMEM55B is first identified as phosphatidylinositol-4,5-P24-phosphatases (PtdIns-4,5-P24-phosphatases) that catalyse dephosphorylation of PtdIns-4,5-P2 to PtdIns-5-P. We demonstrate for the first time that TMEM55B is phosphorylated by Erk/MAPK and that this mechanism participates in regulation of lysosomal clustering. Exposure of RAW264.7 macrophages to various stimuli induces phosphorylation of TMEM55B on Ser76 and Ser169, sites corresponding to consensus sequences (PX(S/T)P) for phosphorylation by MAPK. Of these stimuli, Toll-like receptor ligands most strongly induce TMEM55B phosphorylation, and this is blocked by the MEK1/2 inhibitor U0126. However, phosphorylation does not impact intrinsic phosphatase activity of TMEM55B. TMEM55B has recently been implicated in starvation induced lysosomal translocation. Amino acid starvation induces perinuclear lamp1 clustering in RAW264.7 macrophages, which was attenuated by shRNA-mediated knock-down or CRISPR/Cas9-mediated knock-out of TMEM55B. Cells exposed to U0126 also exhibit attenuated lamp1 clustering. Overexpression of TMEM55B but not TMEM55A notably enhances lamp1 clustering, with TMEM55B mutants (lacking phosphorylation sites or mimicking the phosphorylated state) exhibiting lower and higher efficacies (respectively) than wild-type TMEM55B. Collectively, results suggest that phosphorylation of TMEM55B by Erk/MAPK impacts lysosomal dynamics.
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Affiliation(s)
- Shinya Takemasu
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kiyomi Nigorikawa
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Miho Yamada
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Go Tsurumi
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Satoshi Kofuji
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Shunsuke Takasuga
- Department of Pathology and Immunology, Akita University School of Medicine, Akita, Japan
| | - Kaoru Hazeki
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
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29
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Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids. Biochem J 2019; 476:1-23. [PMID: 30617162 DOI: 10.1042/bcj20180022] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/03/2018] [Accepted: 12/07/2018] [Indexed: 12/15/2022]
Abstract
Polyphosphoinositides (PPIs) are essential phospholipids located in the cytoplasmic leaflet of eukaryotic cell membranes. Despite contributing only a small fraction to the bulk of cellular phospholipids, they make remarkable contributions to practically all aspects of a cell's life and death. They do so by recruiting cytoplasmic proteins/effectors or by interacting with cytoplasmic domains of membrane proteins at the membrane-cytoplasm interface to organize and mold organelle identity. The present study summarizes aspects of our current understanding concerning the metabolism, manipulation, measurement, and intimate roles these lipids play in regulating membrane homeostasis and vital cell signaling reactions in health and disease.
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30
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Phospholipids and inositol phosphates linked to the epigenome. Histochem Cell Biol 2018; 150:245-253. [DOI: 10.1007/s00418-018-1690-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2018] [Indexed: 12/17/2022]
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31
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Hashimoto Y, Shirane M, Nakayama KI. TMEM55B contributes to lysosomal homeostasis and amino acid-induced mTORC1 activation. Genes Cells 2018; 23:418-434. [DOI: 10.1111/gtc.12583] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 03/13/2018] [Indexed: 01/28/2023]
Affiliation(s)
- Yutaka Hashimoto
- Department of Molecular and Cellular Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka Japan
| | - Michiko Shirane
- Department of Molecular and Cellular Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka Japan
- Department of Molecular Biology; Graduate School of Pharmaceutical Science; Nagoya City University; Nagoya Japan
| | - Keiichi I. Nakayama
- Department of Molecular and Cellular Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka Japan
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32
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Wang L, Wang Y, Duan C, Yang Q. Inositol phosphatase INPP4A inhibits the apoptosis of in vitro neurons with characteristic of intractable epilepsy by reducing intracellular Ca 2+ concentration. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2018; 11:1999-2007. [PMID: 31938306 PMCID: PMC6958220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 08/09/2017] [Indexed: 06/10/2023]
Abstract
Epilepsy is a chronic neurological disorder characterized by recurrent seizures. Seizures can be controlled for most epilepsy patients after drug therapy, but at least 20% of patients develop intractable epilepsy (IE). The mechanism by which IE causes neuronal damage has not been completely understood. Inositol polyphosphate 4 phosphatase (INPP4A), a magnesium-dependent phosphatase, is shown to be associated with glutamate excitotoxicity. Herein, we show that INPP4A plays an essential role in seizure-induced neuronal apoptosis using an in vitro IE neuron model. In this model, INPP4A expression significantly decreased compared to normal neurons. Our results showed that overexpression of INPP4A significantly inhibited LDH activity and increased cell viability while knockdown of INPP4A markedly increased LDH activity and inhibited cell viability. Similarly, overexpression of INPP4A significantly enhanced G1 phase transition to S phase and inhibited apoptosis while knockdown of INPP4A significantly inhibited cell cycle progression and increased apoptosis in IE neurons. Furthermore, INPP4A-mediated inhibition of apoptosis might be associated with reduced intracellular Ca2+ concentration. Our findings thus support the results of the previous in vivo studies that INPP4A is linked to the pathogenesis and progression of intractable epilepsy, which suggest that INPP4A may be an important target against epilepsy, especially IE.
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Affiliation(s)
- Li Wang
- Department of Neurology of The Second Affiliated Hospital, Third Military Medical University No. 1 Xinqiao Main Street, Shapingba District, Chongqing 40037, China
| | - Yue Wang
- Department of Neurology of The Second Affiliated Hospital, Third Military Medical University No. 1 Xinqiao Main Street, Shapingba District, Chongqing 40037, China
| | - Chunmei Duan
- Department of Neurology of The Second Affiliated Hospital, Third Military Medical University No. 1 Xinqiao Main Street, Shapingba District, Chongqing 40037, China
| | - Qingwu Yang
- Department of Neurology of The Second Affiliated Hospital, Third Military Medical University No. 1 Xinqiao Main Street, Shapingba District, Chongqing 40037, China
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Lloyd-Lewis B, Krueger CC, Sargeant TJ, D'Angelo ME, Deery MJ, Feret R, Howard JA, Lilley KS, Watson CJ. Stat3-mediated alterations in lysosomal membrane protein composition. J Biol Chem 2018; 293:4244-4261. [PMID: 29343516 PMCID: PMC5868265 DOI: 10.1074/jbc.ra118.001777] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Indexed: 12/19/2022] Open
Abstract
Lysosome function is essential in cellular homeostasis. In addition to its recycling role, the lysosome has recently been recognized as a cellular signaling hub. We have shown in mammary epithelial cells, both in vivo and in vitro, that signal transducer and activator of transcription 3 (Stat3) modulates lysosome biogenesis and can promote the release of lysosomal proteases that culminates in cell death. To further investigate the impact of Stat3 on lysosomal function, we conducted a proteomic screen of changes in lysosomal membrane protein components induced by Stat3 using an iron nanoparticle enrichment strategy. Our results show that Stat3 activation not only elevates the levels of known membrane proteins but results in the appearance of unexpected factors, including cell surface proteins such as annexins and flotillins. These data suggest that Stat3 may coordinately regulate endocytosis, intracellular trafficking, and lysosome biogenesis to drive lysosome-mediated cell death in mammary epithelial cells. The methodologies described in this study also provide significant improvements to current techniques used for the purification and analysis of the lysosomal proteome.
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Affiliation(s)
- Bethan Lloyd-Lewis
- From the Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom,
| | - Caroline C Krueger
- From the Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Timothy J Sargeant
- the Lysosomal Diseases Research Unit, South Australian Health and Medical Research Institute, Adelaide, South Australia 5000, Australia, and
| | - Michael E D'Angelo
- From the Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Michael J Deery
- the Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom
| | - Renata Feret
- the Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom
| | - Julie A Howard
- the Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom
| | - Kathryn S Lilley
- the Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom
| | - Christine J Watson
- From the Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom,
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34
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Morioka S, Nigorikawa K, Okada E, Tanaka Y, Kasuu Y, Yamada M, Kofuji S, Takasuga S, Nakanishi H, Sasaki T, Hazeki K. TMEM55a localizes to macrophage phagosomes to downregulate phagocytosis. J Cell Sci 2018; 131:jcs.213272. [PMID: 29378918 DOI: 10.1242/jcs.213272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/22/2018] [Indexed: 01/29/2023] Open
Abstract
TMEM55a (also known as PIP4P2) is an enzyme that dephosphorylates the phosphatidylinositol (PtdIns) PtdIns(4,5)P2 to form PtdIns(5)P in vitro However, the in vivo conversion of the polyphosphoinositide into PtdIns(5)P by the phosphatase has not yet been demonstrated, and the role of TMEM55a remains poorly understood. Here, we found that mouse macrophages (Raw264.7) deficient in TMEM55a showed an increased engulfment of large particles without affecting the phagocytosis of Escherichia coli Transfection of a bacterial phosphatase with similar substrate specificity to TMEM55a, namely IpgD, into Raw264.7 cells inhibited the engulfment of IgG-erythrocytes in a manner dependent on its phosphatase activity. In contrast, cells transfected with PIP4K2a, which catalyzes PtdIns(4,5)P2 production from PtdIns(5)P, increased phagocytosis. Fluorescent TMEM55a transfected into Raw264.7 cells was found to mostly localize to the phagosome. The accumulation of PtdIns(4,5)P2, PtdIns(3,4,5)P3 and F-actin on the phagocytic cup was increased in TMEM55a-deficient cells, as monitored by live-cell imaging. Phagosomal PtdIns(5)P was decreased in the knockdown cells, but the augmentation of phagocytosis in these cells was unaffected by the exogenous addition of PtdIns(5)P. Taken together, these results suggest that TMEM55a negatively regulates the phagocytosis of large particles by reducing phagosomal PtdIns(4,5)P2 accumulation during cup formation.
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Affiliation(s)
- Shin Morioka
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Kiyomi Nigorikawa
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Eri Okada
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Yoshimasa Tanaka
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Yoshihiro Kasuu
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Miho Yamada
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Satoshi Kofuji
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
| | - Shunsuke Takasuga
- Department of Pathology and Immunology, Akita University School of Medicine, Akita 010-8543, Japan
| | - Hiroki Nakanishi
- Research Center for Biosignal, Akita University School of Medicine, Akita 010-8543, Japan
| | - Takehiko Sasaki
- Department of Pathology and Immunology, Akita University School of Medicine, Akita 010-8543, Japan
| | - Kaoru Hazeki
- Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima 734-8553, Japan
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Abstract
In higher eukaryotes, the Tyr phosphorylation status of cellular proteins results from the coordinated action of Protein Tyrosine Kinases (PTKs) and Protein Tyrosine Phosphatases (PTPs). PTPs have emerged as highly regulated enzymes with diverse substrate specificity, and proteins with Tyr-dephosphorylation or Tyr-dephosphorylation-like properties can be clustered as the PTPome. This includes proteins from the PTP superfamily, which display a Cys-based catalytic mechanism, as well as enzymes from other gene families (Asp-based phosphatases, His-based phosphatases) that have converged in protein Tyr-dephosphorylation-related functions by using non-Cys-based catalytic mechanisms. Within the Cys-based members of the PTPome, classical PTPs dephosphorylate specific phosphoTyr (pTyr) residues from protein substrates, whereas VH1-like dual-specificity PTPs dephosphorylate pTyr, pSer, and pThr residues, as well as nonproteinaceous substrates, including phosphoinositides and phosphorylated carbohydrates. In addition, several PTPs have impaired catalytic activity as a result of amino acid substitutions at their active sites, but retain regulatory functions related with pTyr signaling. As a result of their relevant biological activity, many PTPs are linked to human disease, including cancer, neurodevelopmental, and metabolic diseases, making these proteins important drug targets and molecular markers in the clinic. Here, a brief overview on the biochemistry and physiology of the different groups of proteins that belong to the mammalian PTPome is presented.
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36
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Willett R, Martina JA, Zewe JP, Wills R, Hammond GRV, Puertollano R. TFEB regulates lysosomal positioning by modulating TMEM55B expression and JIP4 recruitment to lysosomes. Nat Commun 2017; 8:1580. [PMID: 29146937 PMCID: PMC5691037 DOI: 10.1038/s41467-017-01871-z] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/20/2017] [Indexed: 12/27/2022] Open
Abstract
Lysosomal distribution is linked to the role of lysosomes in many cellular functions, including autophagosome degradation, cholesterol homeostasis, antigen presentation, and cell invasion. Alterations in lysosomal positioning contribute to different human pathologies, such as cancer, neurodegeneration, and lysosomal storage diseases. Here we report the identification of a novel mechanism of lysosomal trafficking regulation. We found that the lysosomal transmembrane protein TMEM55B recruits JIP4 to the lysosomal surface, inducing dynein-dependent transport of lysosomes toward the microtubules minus-end. TMEM55B overexpression causes lysosomes to collapse into the cell center, whereas depletion of either TMEM55B or JIP4 results in dispersion toward the cell periphery. TMEM55B levels are transcriptionally upregulated following TFEB and TFE3 activation by starvation or cholesterol-induced lysosomal stress. TMEM55B or JIP4 depletion abolishes starvation-induced retrograde lysosomal transport and prevents autophagosome-lysosome fusion. Overall our data suggest that the TFEB/TMEM55B/JIP4 pathway coordinates lysosome movement in response to a variety of stress conditions.
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Affiliation(s)
- Rose Willett
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA
| | - José A Martina
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA
| | - James P Zewe
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Rachel Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, 200 Lothrop Street, Room S332 Biomedical Sciences Tower, Pittsburgh, PA, 15213, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, Building 50, Room 3537, Bethesda, MD, 20892, USA.
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Hasegawa J, Strunk BS, Weisman LS. PI5P and PI(3,5)P 2: Minor, but Essential Phosphoinositides. Cell Struct Funct 2017; 42:49-60. [PMID: 28302928 DOI: 10.1247/csf.17003] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In most eukaryotes, phosphoinositides (PIs) have crucial roles in multiple cellular functions. Although the cellular levels of phosphatidylinositol 5-phosphate (PI5P) and phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) are extremely low relative to some other PIs, emerging evidence demonstrates that both lipids are crucial for the endocytic pathway, intracellular signaling, and adaptation to stress. Mutations that causes defects in the biosynthesis of PI5P and PI(3,5)P2 are linked to human diseases including neurodegenerative disorders. Here, we review recent findings on cellular roles of PI5P and PI(3,5)P2, as well as the pathophysiological importance of these lipids.Key words: Phosphoinositides, Membrane trafficking, Endocytosis, Vacuoles/Lysosomes, Fab1/PIKfyve.
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Alonso A, Pulido R. The extended human PTPome: a growing tyrosine phosphatase family. FEBS J 2015; 283:1404-29. [PMID: 26573778 DOI: 10.1111/febs.13600] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 10/02/2015] [Accepted: 11/13/2015] [Indexed: 12/13/2022]
Abstract
Tyr phosphatases are, by definition, enzymes that dephosphorylate phospho-Tyr (pTyr) from proteins. This activity is found in several structurally diverse protein families, including the protein Tyr phosphatase (PTP), arsenate reductase, rhodanese, haloacid dehalogenase (HAD) and His phosphatase (HP) families. Most of these families include members with substrate specificity for non-pTyr substrates, such as phospho-Ser/phospho-Thr, phosphoinositides, phosphorylated carbohydrates, mRNAs, or inorganic moieties. A Cys is essential for catalysis in PTPs, rhodanese and arsenate reductase enzymes, whereas this work is performed by an Asp in HAD phosphatases and by a His in HPs, via a catalytic mechanism shared by all of the different families. The category that contains most Tyr phosphatases is the PTP family, which, although it received its name from this activity, includes Ser, Thr, inositide, carbohydrate and RNA phosphatases, as well as some inactive pseudophosphatase proteins. Here, we propose an extended collection of human Tyr phosphatases, which we call the extended human PTPome. The addition of new members (SACs, paladin, INPP4s, TMEM55s, SSU72, and acid phosphatases) to the currently categorized PTP group of enzymes means that the extended human PTPome contains up to 125 proteins, of which ~ 40 are selective for pTyr. We set criteria to ascribe proteins to the extended PTPome, and summarize the more important features of the new PTPome members in the context of their phosphatase activity and their relationship with human disease.
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Affiliation(s)
- Andrés Alonso
- Instituto de Biología y Genética Molecular (IBGM), CSIC-Universidad de Valladolid, Valladolid, Spain
| | - Rafael Pulido
- Biocruces Health Research Institute, Barakaldo, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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Rudge SA, Wakelam MJO. Phosphatidylinositolphosphate phosphatase activities and cancer. J Lipid Res 2015; 57:176-92. [PMID: 26302980 DOI: 10.1194/jlr.r059154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Indexed: 12/13/2022] Open
Abstract
Signaling through the phosphoinositide 3-kinase pathways mediates the actions of a plethora of hormones, growth factors, cytokines, and neurotransmitters upon their target cells following receptor occupation. Overactivation of these pathways has been implicated in a number of pathologies, in particular a range of malignancies. The tight regulation of signaling pathways necessitates the involvement of both stimulatory and terminating enzymes; inappropriate activation of a pathway can thus result from activation or inhibition of the two signaling arms. The focus of this review is to discuss, in detail, the activities of the identified families of phosphoinositide phosphatase expressed in humans, and how they regulate the levels of phosphoinositides implicated in promoting malignancy.
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Affiliation(s)
- Simon A Rudge
- Signalling Programme, Babraham Institute, Cambridge CB22 3AT, United Kingdom
| | - Michael J O Wakelam
- Signalling Programme, Babraham Institute, Cambridge CB22 3AT, United Kingdom
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Montjean R, Aoidi R, Desbois P, Rucci J, Trichet M, Salomon R, Rendu J, Fauré J, Lunardi J, Gacon G, Billuart P, Dorseuil O. OCRL-mutated fibroblasts from patients with Dent-2 disease exhibit INPP5B-independent phenotypic variability relatively to Lowe syndrome cells. Hum Mol Genet 2014; 24:994-1006. [PMID: 25305077 DOI: 10.1093/hmg/ddu514] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
OCRL mutations are associated with both Lowe syndrome and Dent-2 disease, two rare X-linked conditions. Lowe syndrome is an oculo-cerebro-renal disorder, whereas Dent-2 patients mainly present renal proximal tubulopathy. Loss of OCRL-1, a phosphoinositide-5-phosphatase, leads in Lowe patients' fibroblasts to phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) accumulation, with defects in F-actin network, α-actinin distribution and ciliogenesis, whereas fibroblasts of Dent-2 patients are still uncharacterized. To search for mechanisms linked to clinical variability observed between these two OCRL mutation-associated pathologies, we compared dermal fibroblasts from independent patients, four affected by Dent-2 disease and six with Lowe syndrome. For the first time, we describe that Dent-2 fibroblasts with OCRL loss-of-function (LOF) mutations exhibit decrease in actin stress fibers, appearance of punctate α-actinin signals and alteration in primary cilia formation. Interestingly, we quantified these phenotypes as clearly intermediate between Lowe and control fibroblasts, thus suggesting that levels of these defects correlate with clinical variations observed between patients with OCRL mutations. In addition, we show that Lowe and Dent-2 fibroblasts display similar PI(4,5)P2 accumulation levels. Finally, we analyzed INPP5B, a paralogous gene already reported to exhibit functional redundancy with OCRL, and report neither differences in its expression at RNA or protein levels, nor specific allelic variations between fibroblasts of patients. Altogether, we describe here differential phenotypes between fibroblasts from Lowe and Dent-2 patients, both associated with OCRL LOF mutations, we exclude direct roles of PI(4,5)P2 and INPP5B in this phenotypic variability and we underline potential key alterations leading to ocular and neurological clinical features in Lowe syndrome.
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Affiliation(s)
- Rodrick Montjean
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Rifdat Aoidi
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Pierrette Desbois
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Julien Rucci
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Michaël Trichet
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Rémi Salomon
- Service de Néphrologie Pédiatrique, Hôpital Necker Enfants Malades, Paris, France and
| | - John Rendu
- Laboratoire de Biochimie et Génétique Moléculaire, CHU de Grenoble, Grenoble, France
| | - Julien Fauré
- Laboratoire de Biochimie et Génétique Moléculaire, CHU de Grenoble, Grenoble, France
| | - Joël Lunardi
- Laboratoire de Biochimie et Génétique Moléculaire, CHU de Grenoble, Grenoble, France
| | - Gérard Gacon
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Pierre Billuart
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France
| | - Olivier Dorseuil
- INSERM U1016, Institut Cochin, Paris, France, CNRS UMR8104, Paris, France, Université Paris Descartes, Paris, France,
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Bulley SJ, Clarke JH, Droubi A, Giudici ML, Irvine RF. Exploring phosphatidylinositol 5-phosphate 4-kinase function. Adv Biol Regul 2014; 57:193-202. [PMID: 25311266 PMCID: PMC4359101 DOI: 10.1016/j.jbior.2014.09.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 11/30/2022]
Abstract
The family of phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks) is emerging from a comparative backwater in inositide signalling into the mainstream, as is their substrate, phosphatidylinositol 5-phosphate (PI5P). Here we review some of the key questions about the PI5P4Ks, their localisation, interaction, and regulation and also we summarise our current understanding of how PI5P is synthesised and what its cellular functions might be. Finally, some of the evidence for the involvement of PI5P4Ks in pathology is discussed.
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Affiliation(s)
- Simon J Bulley
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Jonathan H Clarke
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Alaa Droubi
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | | | - Robin F Irvine
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK.
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LaBonte ML. Anticoagulant factor V: factors affecting the integration of novel scientific discoveries into the broader framework. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2014; 47 Pt A:23-34. [PMID: 24853975 DOI: 10.1016/j.shpsc.2014.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 03/21/2014] [Accepted: 03/25/2014] [Indexed: 06/03/2023]
Abstract
Since its initial discovery in the 1940s, factor V has long been viewed as an important procoagulant protein in the coagulation cascade. However, in the later part of the 20th century, two different scientists proposed novel anticoagulant roles for factor V. Philip Majerus proposed the first anticoagulant function for factor V in 1983, yet ultimately it was not widely accepted by the broader scientific community. In contrast, Björn Dahlbäck proposed a different anticoagulant role for factor V in 1994. While this role was initially contested, it was ultimately accepted and integrated into the scientific framework. In this paper, I present a detailed historical account of these two anticoagulant discoveries and propose three key reasons why Dahlbäck's anticoagulant role for factor V was accepted whereas Majerus' proposed role was largely overlooked. Perhaps most importantly, Dahlbäck's proposed anticoagulant role was of great clinical interest because the discovery involved the study of an important subset of patients with thrombophilia. Soon after Dahlbäck's 1994 work, this patient population was shown to possess the factor V Leiden mutation. Also key in the ultimate acceptance of the second proposed anticoagulant role was the persistence of the scientist who made the discovery and the interest in and ability of others to replicate and reinforce this work. This analysis of two different yet similar discoveries sheds light on factors that play an important role in how new discoveries are incorporated into the existing scientific framework.
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Affiliation(s)
- Michelle L LaBonte
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA 02481, USA.
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Swanson JA. Phosphoinositides and engulfment. Cell Microbiol 2014; 16:1473-83. [PMID: 25073505 DOI: 10.1111/cmi.12334] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 07/17/2014] [Accepted: 07/28/2014] [Indexed: 12/24/2022]
Abstract
Cellular engulfment of particles, cells or solutes displaces large domains of plasma membrane into intracellular membranous vacuoles. This transfer of membrane is accompanied by major transitions of the phosphoinositide (PI) species that comprise the cytoplasmic face of membrane bilayers. Mapping of membrane PIs during engulfment reveals distinct patterns of protein and PI distributions associated with each stage of engulfment, which correspond with activities that regulate the actin cytoskeleton, membrane movements and vesicle secretion. Experimental manipulation of PI chemistry during engulfment indicates that PIs integrate organelle identity and orient signal transduction cascades within confined subdomains of membrane. These pathways are exploited by microbial pathogens to direct or redirect the engulfment process.
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Affiliation(s)
- Joel A Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109-5620, USA
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Abstract
The specific interaction of phosphoinositides with proteins is critical for a plethora of cellular processes, including cytoskeleton remodelling, mitogenic signalling, ion channel regulation and membrane traffic. The spatiotemporal restriction of different phosphoinositide species helps to define compartments within the cell, and this is particularly important for membrane trafficking within both the secretory and endocytic pathways. Phosphoinositide homoeostasis is tightly regulated by a large number of inositol kinases and phosphatases, which respectively phosphorylate and dephosphorylate distinct phosphoinositide species. Many of these enzymes have been implicated in regulating membrane trafficking and, accordingly, their dysregulation has been linked to a number of human diseases. In the present review, we focus on the inositol phosphatases, concentrating on their roles in membrane trafficking and the human diseases with which they have been associated.
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45
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Medina MW, Bauzon F, Naidoo D, Theusch E, Stevens K, Schilde J, Schubert C, Mangravite LM, Rudel LL, Temel RE, Runz H, Krauss RM. Transmembrane protein 55B is a novel regulator of cellular cholesterol metabolism. Arterioscler Thromb Vasc Biol 2014; 34:1917-23. [PMID: 25035345 DOI: 10.1161/atvbaha.113.302806] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Interindividual variation in pathways affecting cellular cholesterol metabolism can influence levels of plasma cholesterol, a well-established risk factor for cardiovascular disease. Inherent variation among immortalized lymphoblastoid cell lines from different donors can be leveraged to discover novel genes that modulate cellular cholesterol metabolism. The objective of this study was to identify novel genes that regulate cholesterol metabolism by testing for evidence of correlated gene expression with cellular levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) mRNA, a marker for cellular cholesterol homeostasis, in a large panel of lymphoblastoid cell lines. APPROACH AND RESULTS Expression array profiling was performed on 480 lymphoblastoid cell lines established from participants of the Cholesterol and Pharmacogenetics (CAP) statin clinical trial, and transcripts were tested for evidence of correlated expression with HMGCR as a marker of intracellular cholesterol homeostasis. Of these, transmembrane protein 55b (TMEM55B) showed the strongest correlation (r=0.29; P=4.0E-08) of all genes not previously implicated in cholesterol metabolism and was found to be sterol regulated. TMEM55B knockdown in human hepatoma cell lines promoted the decay rate of the low-density lipoprotein receptor, reduced cell surface low-density lipoprotein receptor protein, impaired low-density lipoprotein uptake, and reduced intracellular cholesterol. CONCLUSIONS Here, we report identification of TMEM55B as a novel regulator of cellular cholesterol metabolism through the combination of gene expression profiling and functional studies. The findings highlight the value of an integrated genomic approach for identifying genes that influence cholesterol homeostasis.
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Affiliation(s)
- Marisa W Medina
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.).
| | - Frederick Bauzon
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Devesh Naidoo
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Elizabeth Theusch
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Kristen Stevens
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Jessica Schilde
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Christian Schubert
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lara M Mangravite
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lawrence L Rudel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ryan E Temel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Heiko Runz
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ronald M Krauss
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
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Puhar A, Tronchère H, Payrastre B, Nhieu GTV, Sansonetti PJ. A Shigella effector dampens inflammation by regulating epithelial release of danger signal ATP through production of the lipid mediator PtdIns5P. Immunity 2014; 39:1121-31. [PMID: 24332032 DOI: 10.1016/j.immuni.2013.11.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 10/09/2013] [Indexed: 12/20/2022]
Abstract
Upon infection with Shigella flexneri, epithelial cells release ATP through connexin hemichannels. However, the pathophysiological consequence and the regulation of this process are unclear. Here we showed that in intestinal epithelial cell ATP release was an early alert response to infection with enteric pathogens that eventually promoted inflammation of the gut. Shigella evolved to escape this inflammatory reaction by its type III secretion effector IpgD, which blocked hemichannels via the production of the lipid PtdIns5P. Infection with an ipgD mutant resulted in rapid hemichannel-dependent accumulation of extracellular ATP in vitro and in vivo, which preceded the onset of inflammation. At later stages of infection, ipgD-deficient Shigella caused strong intestinal inflammation owing to extracellular ATP. We therefore describe a new paradigm of host-pathogen interaction based on endogenous danger signaling and identify extracellular ATP as key regulator of mucosal inflammation during infection. Our data provide new angles of attack for the development of anti-inflammatory molecules.
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Affiliation(s)
- Andrea Puhar
- Inserm U786, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France; Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France.
| | - Hélène Tronchère
- Inserm U1048, I2MC, 31432 Toulouse Cedex 4, France; Université Toulouse 3, I2MC, 31432 Toulouse Cedex 4, France
| | - Bernard Payrastre
- Inserm U1048, I2MC, 31432 Toulouse Cedex 4, France; Université Toulouse 3, I2MC, 31432 Toulouse Cedex 4, France; CHU Toulouse, Laboratoire d'Hématologie, 31432 Toulouse Cedex 4, France
| | - Guy Tran Van Nhieu
- Inserm U1050, Equipe Communication Intercellulaire et Infections Microbiennes, CIRB, 75231 Paris Cedex 5, France; CNRS UMR7241, Equipe Communication Intercellulaire et Infections Microbiennes, CIRB, 75231 Paris Cedex 5, France; Collège de France, Equipe Communication Intercellulaire et Infections Microbiennes, CIRB, 75231 Paris Cedex 5, France
| | - Philippe J Sansonetti
- Inserm U786, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France; Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris Cedex 15, France.
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Viaud J, Boal F, Tronchère H, Gaits-Iacovoni F, Payrastre B. Phosphatidylinositol 5-phosphate: A nuclear stress lipid and a tuner of membranes and cytoskeleton dynamics. Bioessays 2013; 36:260-72. [DOI: 10.1002/bies.201300132] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Julien Viaud
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | - Frédéric Boal
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | - Hélène Tronchère
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | | | - Bernard Payrastre
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
- CHU de Toulouse; Laboratoire d'Hématologie; Toulouse France
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48
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Evolutionarily conserved structural changes in phosphatidylinositol 5-phosphate 4-kinase (PI5P4K) isoforms are responsible for differences in enzyme activity and localization. Biochem J 2013; 454:49-57. [PMID: 23758345 PMCID: PMC3749867 DOI: 10.1042/bj20130488] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mammals have genes coding for three PI5P4Ks (PtdIns5P 4-kinases), and these have different cellular localizations, tissue distributions and lipid kinase activities. We describe in the present paper a detailed molecular exploration of human PI5P4Ks α, β and γ, as well as their fly and worm homologues, to understand how and why these differences came to be. The intrinsic ATPase activities of the three isoforms are very similar, and we show that differences in their G-loop regions can account for much of their wide differences in lipid kinase activity. We have also undertaken an extensive in silico evolutionary study of the PI5P4K family, and show experimentally that the single PI5P4K homologues from Caenorhabditis elegans and Drosophila melanogaster are as widely different in activity as the most divergent mammalian isoforms. Finally we show that the close association of PI5P4Ks α and γ is a true heterodimerization, and not a higher oligomer association of homodimers. We reveal that structural modelling is consistent with this and with the apparently random heterodimerization that we had earlier observed between PI5P4Kα and PI5P4Kβ [Wang, Bond, Letcher, Richardson, Lilley, Irvine and Clarke (2010), Biochem. J. 430, 215–221]. Overall the molecular diversity of mammalian PI5P4Ks explains much of their properties and behaviour, but their physiological functionality remains elusive.
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49
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Shisheva A. PtdIns5P: news and views of its appearance, disappearance and deeds. Arch Biochem Biophys 2013; 538:171-80. [PMID: 23916588 DOI: 10.1016/j.abb.2013.07.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/22/2013] [Indexed: 12/24/2022]
Abstract
Accumulated evidence indicates that PtdIns5P, one of the seven phosphoinositides, found now to be constitutively present in yeast, plants and metazoa, serves as a signaling molecule to modulate pleiotropic cellular functions in both the nucleus and the cytoplasm. The enzymatic routes in biogenesis of basal PtdIns5P have remained incompletely understood. The role for candidate kinase PIKfyve that is principally involved in PtdIns(3,5)P2 production, has been questioned. In this review article we scrutinize the past obstacles that prevented the definitive implication of PIKfyve in PtdIns5P biosynthesis from PtdIns and focus on the recent pharmacological and genetic advancements that now make this conclusion well supported. We further summarize our current knowledge of the diverse stimuli modulating PtdIns5P levels, binding partners and regulated cellular process, with particular reference to the available mechanistic insights for the relevant signaling pathways.
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Affiliation(s)
- Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, United States.
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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