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Manzolillo A, Gresing L, Hübner CA, Franzka P. Knockdown of INPP5K compromises the differentiation of N2A cells. Front Mol Neurosci 2024; 17:1356343. [PMID: 38559586 PMCID: PMC10979461 DOI: 10.3389/fnmol.2024.1356343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
Inositol polyphosphate 5-phosphatase K (INPP5K), also known as SKIP (skeletal muscle and kidney-enriched inositol phosphatase), is a cytoplasmic enzyme with 5-phosphatase activity toward phosphoinositides (PIs). Mutations in INPP5K are associated with autosomal recessive congenital muscular dystrophy with cataracts and intellectual disability (MDCCAID). Notably, muscular dystrophy is characterized by the hypoglycosylation of dystroglycan. Thus, far, the underlying mechanisms are only partially understood. In this study, we show that INPP5K expression increases during brain development. Knockdown of INPP5K in the neuroblastoma-derived cell line N2A impaired their neuronal-like differentiation and interfered with protein glycosylation.
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Affiliation(s)
- Annamaria Manzolillo
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Lennart Gresing
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Christian A. Hübner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Center of Rare Diseases, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Patricia Franzka
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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2
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Srivastav S, van der Graaf K, Singh P, Utama AB, Meyer MD, McNew JA, Stern M. Atl (atlastin) regulates mTor signaling and autophagy in Drosophila muscle through alteration of the lysosomal network. Autophagy 2024; 20:131-150. [PMID: 37649246 PMCID: PMC10761077 DOI: 10.1080/15548627.2023.2249794] [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: 03/06/2023] [Revised: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 09/01/2023] Open
Abstract
ABBREVIATIONS atl atlastin; ALR autophagic lysosome reformation; ER endoplasmic reticulum; GFP green fluorescent protein; HSP hereditary spastic paraplegia; Lamp1 lysosomal associated membrane protein 1 PolyUB polyubiquitin; RFP red fluorescent protein; spin spinster; mTor mechanistic Target of rapamycin; VCP valosin containing protein.
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Affiliation(s)
| | | | - Pratibha Singh
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | | | - Matthew D. Meyer
- Shared Equipment Authority, Rice University, Houston, Texas, USA
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, Texas, USA
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3
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Loncke J, Luyten T, Ramos AR, Erneux C, Bultynck G. Loss of INPP5K attenuates IP 3-induced Ca 2+ responses in the glioblastoma cell line U-251 MG cells. BBA ADVANCES 2023; 4:100105. [PMID: 37842182 PMCID: PMC10568277 DOI: 10.1016/j.bbadva.2023.100105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 09/19/2023] [Accepted: 09/26/2023] [Indexed: 10/17/2023] Open
Abstract
INPP5K (inositol polyphosphate 5-phosphatase K) is an endoplasmic reticulum (ER)-resident enzyme that acts as a phosphoinositide (PI) 5-phosphatase, capable of dephosphorylating various PIs including PI 4,5-bisphosphate (PI(4,5)P2), a key phosphoinositide found in the plasma membrane. Given its ER localization and substrate specificity, INPP5K may play a role in ER-plasma membrane contact sites. Furthermore, PI(4,5)P2 serves as a substrate for phospholipase C, an enzyme activated downstream of extracellular agonists acting on Gq-coupled receptors or tyrosine-kinase receptors, leading to IP3 production and subsequent release of Ca2+ from the ER, the primary intracellular Ca2+ storage organelle. In this study, we investigated the impact of INPP5K on ER Ca2+ dynamics using a previously established INPP5K-knockdown U-251 MG glioblastoma cell model. We here describe that loss of INPP5K impairs agonist-induced, IP3 receptor (IP3R)-mediated Ca2+ mobilization in intact cells, while the ER Ca2+ content and store-operated Ca2+ influx remain unaffected. To further elucidate the underlying mechanisms, we examined Ca2+ release in permeabilized cells stimulated with exogenous IP3. Interestingly, the absence of INPP5K also disrupted IP3-induced Ca2+ release events. These results suggest that INPP5K may directly influence IP3R activity through mechanisms yet to be resolved. The findings from this study point towards role of INPP5K in modulating ER calcium dynamics, particularly in relation to IP3-mediated signaling pathways. However, further work is needed to establish the general nature of our findings and to unravel the exact molecular mechanisms underlying the interplay between INNP5K function and Ca2+ signaling.
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Affiliation(s)
- Jens Loncke
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
| | - Tomas Luyten
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
| | - Ana Raquel Ramos
- ULB, IRIBHM, Campus Erasme, Bâtiment C, 808 Route de Lennik, Bruxelles 1070, Belgium
| | - Christophe Erneux
- ULB, IRIBHM, Campus Erasme, Bâtiment C, 808 Route de Lennik, Bruxelles 1070, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
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4
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Shukla D, Gural BM, Cauley ES, Battula N, Mowla S, Karas BF, Roberts LE, Cavallo L, Turkalj L, Moody SA, Swan LE, Manzini MC. Duplicated zebrafish (Danio rerio) inositol phosphatases inpp5ka and inpp5kb diverged in expression pattern and function. Dev Genes Evol 2023; 233:25-34. [PMID: 37184573 PMCID: PMC10239392 DOI: 10.1007/s00427-023-00703-z] [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: 08/31/2022] [Accepted: 04/27/2023] [Indexed: 05/16/2023]
Abstract
One hurdle in the development of zebrafish models of human disease is the presence of multiple zebrafish orthologs resulting from whole genome duplication in teleosts. Mutations in inositol polyphosphate 5-phosphatase K (INPP5K) lead to a syndrome characterized by variable presentation of intellectual disability, brain abnormalities, cataracts, muscle disease, and short stature. INPP5K is a phosphatase acting at position 5 of phosphoinositides to control their homeostasis and is involved in insulin signaling, cytoskeletal regulation, and protein trafficking. Previously, our group and others have replicated the human phenotypes in zebrafish knockdown models by targeting both INPP5K orthologs inpp5ka and inpp5kb. Here, we show that inpp5ka is the more closely related orthologue to human INPP5K. While both inpp5ka and inpp5kb mRNA expression levels follow a similar trend in the developing head, eyes, and tail, inpp5ka is much more abundantly expressed in these tissues than inpp5kb. In situ hybridization revealed a similar trend, also showing unique localization of inpp5kb in the pineal gland and retina indicating different transcriptional regulation. We also found that inpp5kb has lost its catalytic activity against its preferred substrate, PtdIns(4,5)P2. Since most human mutations are missense changes disrupting phosphatase activity, we propose that loss of inpp5ka alone can be targeted to recapitulate the human presentation. In addition, we show that the function of inpp5kb has diverged from inpp5ka and may play a novel role in the zebrafish.
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Affiliation(s)
- Dhyanam Shukla
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Brian M Gural
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Edmund S Cauley
- Department of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA
| | - Namarata Battula
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Shorbon Mowla
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Brittany F Karas
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Llion E Roberts
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Luca Cavallo
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Luka Turkalj
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA
| | - Laura E Swan
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Chiara Manzini
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA.
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5
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Davies EM, Gurung R, Le KQ, Roan KT, Harvey RP, Mitchell GM, Schwarz Q, Mitchell CA. PI(4,5)P 2-dependent regulation of endothelial tip cell specification contributes to angiogenesis. SCIENCE ADVANCES 2023; 9:eadd6911. [PMID: 37000875 PMCID: PMC10065449 DOI: 10.1126/sciadv.add6911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 02/24/2023] [Indexed: 06/19/2023]
Abstract
Dynamic positioning of endothelial tip and stalk cells, via the interplay between VEGFR2 and NOTCH signaling, is essential for angiogenesis. VEGFR2 activates PI3K, which phosphorylates PI(4,5)P2 to PI(3,4,5)P3, activating AKT; however, PI3K/AKT does not direct tip cell specification. We report that PI(4,5)P2 hydrolysis by the phosphoinositide-5-phosphatase, INPP5K, contributes to angiogenesis. INPP5K ablation disrupted tip cell specification and impaired embryonic angiogenesis associated with enhanced DLL4/NOTCH signaling. INPP5K degraded a pool of PI(4,5)P2 generated by PIP5K1C phosphorylation of PI(4)P in endothelial cells. INPP5K ablation increased PI(4,5)P2, thereby releasing β-catenin from the plasma membrane, and concurrently increased PI(3,4,5)P3-dependent AKT activation, conditions that licensed DLL4/NOTCH transcription. Suppression of PI(4,5)P2 in INPP5K-siRNA cells by PIP5K1C-siRNA, restored β-catenin membrane localization and normalized AKT signaling. Pharmacological NOTCH or AKT inhibition in vivo or genetic β-catenin attenuation rescued angiogenesis defects in INPP5K-null mice. Therefore, PI(4,5)P2 is critical for β-catenin/DLL4/NOTCH signaling, which governs tip cell specification during angiogenesis.
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Affiliation(s)
- Elizabeth M. Davies
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Rajendra Gurung
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Kai Qin Le
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Katherine T. T. Roan
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Richard P. Harvey
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
- School of Clinical Medicine and School of Biotechnology and Biomolecular Science, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Geraldine M. Mitchell
- O’Brien Institute Department of St Vincent’s Institute and University of Melbourne, Department of Surgery, St. Vincent’s Hospital, Fitzroy, Victoria 3065, Australia
- Health Sciences Faculty, Australian Catholic University, Fitzroy, Victoria 3065, Australia
| | - Quenten Schwarz
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, South Australia 5001, Australia
| | - Christina A. Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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Inositol Polyphosphate-5-Phosphatase K ( Inpp5k) Enhances Sprouting of Corticospinal Tract Axons after CNS Trauma. J Neurosci 2022; 42:2190-2204. [PMID: 35135857 PMCID: PMC8936595 DOI: 10.1523/jneurosci.0897-21.2022] [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: 04/27/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 11/21/2022] Open
Abstract
Failure of CNS neurons to mount a significant growth response after trauma contributes to chronic functional deficits after spinal cord injury. Activator and repressor screening of embryonic cortical neurons and retinal ganglion cells in vitro and transcriptional profiling of developing CNS neurons harvested in vivo have identified several candidates that stimulate robust axon growth in vitro and in vivo Building on these studies, we sought to identify novel axon growth activators induced in the complex adult CNS environment in vivo We transcriptionally profiled intact sprouting adult corticospinal neurons (CSNs) after contralateral pyramidotomy (PyX) in nogo receptor-1 knock-out mice and found that intact CSNs were enriched in genes in the 3-phosphoinositide degradation pathway, including six 5-phosphatases. We explored whether inositol polyphosphate-5-phosphatase K (Inpp5k) could enhance corticospinal tract (CST) axon growth in preclinical models of acute and chronic CNS trauma. Overexpression of Inpp5k in intact adult CSNs in male and female mice enhanced the sprouting of intact CST terminals after PyX and cortical stroke and sprouting of CST axons after acute and chronic severe thoracic spinal contusion. We show that Inpp5k stimulates axon growth in part by elevating the density of active cofilin in labile growth cones, thus stimulating actin polymerization and enhancing microtubule protrusion into distal filopodia. We identify Inpp5k as a novel CST growth activator capable of driving compensatory axon growth in multiple complex CNS injury environments and underscores the veracity of using in vivo transcriptional screening to identify the next generation of cell-autonomous factors capable of repairing the damaged CNS.SIGNIFICANCE STATEMENT Neurologic recovery is limited after spinal cord injury as CNS neurons are incapable of self-repair post-trauma. In vitro screening strategies exploit the intrinsically high growth capacity of embryonic CNS neurons to identify novel axon growth activators. While promising candidates have been shown to stimulate axon growth in vivo, concomitant functional recovery remains incomplete. We identified Inpp5k as a novel axon growth activator using transcriptional profiling of intact adult corticospinal tract (CST) neurons that had initiated a growth response after pyramidotomy in plasticity sensitized nogo receptor-1-null mice. Here, we show that Inpp5k overexpression can stimulate CST axon growth after pyramidotomy, stroke, and acute and chronic contusion injuries. These data support in vivo screening approaches to identify novel axon growth activators.
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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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8
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KDM1A inhibition augments the efficacy of rapamycin for the treatment of endometrial cancer. Cancer Lett 2022; 524:219-231. [PMID: 34673129 PMCID: PMC10000284 DOI: 10.1016/j.canlet.2021.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/30/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022]
Abstract
Endometrial cancer (EC) often exhibit aberrant activation of PI3K/Akt/mTOR signaling and targeted therapies using mTOR inhibitors showed limited success. The epigenetic modifier, lysine-specific histone demethylase-1A (KDM1A/LSD1) is overexpressed in EC, however, the mechanistic and therapeutic implications of KDM1A in EC are poorly understood. Here, using 119 FDA-approved drugs screen, we identified that KDM1A inhibition is highly synergistic with mTOR inhibitors. Combination therapy of KDM1A and mTOR inhibitors potently reduced the cell viability, survival, and migration of EC cells. Mechanistic studies demonstrated that KDM1A inhibition attenuated the activation of mTOR signaling cascade and abolished rapamycin induced feedback activation of Akt. RNA-seq analysis identified that KDM1A inhibition downregulated the expression of genes involved in rapamycin induced activation of Akt, including the mTORC2 complex. Chromatin immunoprecipitation experiments confirmed KDM1A recruitment to the promoter regions of mTORC2 complex genes and that KDM1A inhibition promoted enrichment of repressive H3K9me2 marks at their promoters. Combination therapy of KDM1A inhibitor and rapamycin reduced the tumor growth in EC xenograft and patient derived xenograft models in vivo and patient derived tumor explants ex vivo. Importantly, in silico analysis of TCGA EC patients data sets revealed that KDM1A expression positively correlated with the levels of PI3K/Akt/mTOR genes. Collectively, our results provide compelling evidence that KDM1A inhibition potentiates the activity of mTOR inhibitors by attenuating the feedback activation of Akt survival signaling. Furthermore, the use of concurrent KDM1A and mTOR inhibitors may be an attractive targeted therapy for EC patients.
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Jiang L, Chen Y, Min G, Wang J, Chen W, Wang H, Wang X, Yao N. Bcl2-associated athanogene 4 promotes the invasion and metastasis of gastric cancer cells by activating the PI3K/AKT/NF-κB/ZEB1 axis. Cancer Lett 2021; 520:409-421. [PMID: 34419501 DOI: 10.1016/j.canlet.2021.08.020] [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: 04/08/2021] [Revised: 08/14/2021] [Accepted: 08/17/2021] [Indexed: 12/25/2022]
Abstract
Bcl2-associated athanogene 4 (BAG4) has been found to be aberrantly expressed in several types of human cancers. However, little is known about its expression, role, and clinical significance in gastric cancer (GC). In this study, we aimed to address these issues and to explore the underlying mechanisms. The expression level of BAG4, measured by immunohistochemistry, was significantly higher in GC tissues than in paired normal tissues. Elevated BAG4 expression was positively correlated with T stage, lymph node metastasis, and tumor size of GC and was associated with unfavorable outcomes of the patients. The overexpression of BAG4 promoted the in vitro invasion and in vivo metastasis of GC cells, and opposite results were observed after silencing of BAG4. Silencing of BAG4 significantly reduced the phosphorylation of PI3K, AKT, and p65, whereas overexpression of BAG4 markedly enhanced the phosphorylation of these molecules. At the same time, manipulating BAG4 expression resulted in the corresponding changes in p65 nuclear translocation and ZEB1 expression. Luciferase reporter and chromatin immunoprecipitation assays verified that p65 binds to the promoter of ZEB1 to upregulate its transcription. Our results demonstrate that BAG4 plays an oncogenic role in the invasion and metastasis of GC cells by activating the PI3K/AKT/NF-κB/ZEB1 axis to induce epithelial-mesenchymal transition.
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Affiliation(s)
- Lei Jiang
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China.
| | - Yan Chen
- Department of Stomatology, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Guangtao Min
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Jun Wang
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Wei Chen
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Hongpeng Wang
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Xiangwen Wang
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China
| | - Nan Yao
- Sixth Department of General Surgery, The First Hospital of Lanzhou University, Lanzhou, 730000, China.
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Sun J, Harion R, Naito T, Saheki Y. INPP5K and Atlastin-1 maintain the nonuniform distribution of ER-plasma membrane contacts in neurons. Life Sci Alliance 2021; 4:4/11/e202101092. [PMID: 34556534 PMCID: PMC8507493 DOI: 10.26508/lsa.202101092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/03/2021] [Accepted: 09/11/2021] [Indexed: 02/04/2023] Open
Abstract
In neurons, the ER extends throughout all cellular processes, forming multiple contacts with the plasma membrane (PM) to fine-tune neuronal physiology. However, the mechanisms that regulate the distribution of neuronal ER-PM contacts are not known. Here, we used the Caenorhabditis elegans DA9 motor neuron as our model system and found that neuronal ER-PM contacts are enriched in soma and dendrite and mostly absent in axons. Using forward genetic screen, we identified that the inositol 5-phosphatase, CIL-1 (human INPP5K), and the dynamin-like GTPase, ATLN-1 (human Atlastin-1), help to maintain the non-uniform, somatodendritic enrichment of neuronal ER-PM contacts. Mechanistically, CIL-1 acts upstream of ATLN-1 to maintain the balance between ER tubules and sheets. In mutants of CIL-1 or ATLN-1, ER sheets expand and invade into the axon. This is accompanied by the ectopic formation of axonal ER-PM contacts and defects in axon regeneration following laser-induced axotomy. As INPP5K and Atlastin-1 have been linked to neurological disorders, the unique distribution of neuronal ER-PM contacts maintained by these proteins may support neuronal resilience during the onset and progression of these diseases.
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Affiliation(s)
- Jingbo Sun
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Raihanah Harion
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore .,Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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11
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McGrath MJ, Eramo MJ, Gurung R, Sriratana A, Gehrig SM, Lynch GS, Lourdes SR, Koentgen F, Feeney SJ, Lazarou M, McLean CA, Mitchell CA. Defective lysosome reformation during autophagy causes skeletal muscle disease. J Clin Invest 2021; 131:135124. [PMID: 33119550 PMCID: PMC7773396 DOI: 10.1172/jci135124] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 09/23/2020] [Indexed: 12/17/2022] Open
Abstract
The regulation of autophagy-dependent lysosome homeostasis in vivo is unclear. We showed that the inositol polyphosphate 5-phosphatase INPP5K regulates autophagic lysosome reformation (ALR), a lysosome recycling pathway, in muscle. INPP5K hydrolyzes phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] to phosphatidylinositol 4-phosphate [PI(4)P], and INPP5K mutations cause muscular dystrophy by unknown mechanisms. We report that loss of INPP5K in muscle caused severe disease, autophagy inhibition, and lysosome depletion. Reduced PI(4,5)P2 turnover on autolysosomes in Inpp5k–/– muscle suppressed autophagy and lysosome repopulation via ALR inhibition. Defective ALR in Inpp5k–/– myoblasts was characterized by enlarged autolysosomes and the persistence of hyperextended reformation tubules, structures that participate in membrane recycling to form lysosomes. Reduced disengagement of the PI(4,5)P2 effector clathrin was observed on reformation tubules, which we propose interfered with ALR completion. Inhibition of PI(4,5)P2 synthesis or expression of WT INPP5K but not INPP5K disease mutants in INPP5K-depleted myoblasts restored lysosomal homeostasis. Therefore, bidirectional interconversion of PI(4)P/PI(4,5)P2 on autolysosomes was integral to lysosome replenishment and autophagy function in muscle. Activation of TFEB-dependent de novo lysosome biogenesis did not compensate for loss of ALR in Inpp5k–/– muscle, revealing a dependence on this lysosome recycling pathway. Therefore, in muscle, ALR is indispensable for lysosome homeostasis during autophagy and when defective is associated with muscular dystrophy.
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Affiliation(s)
- Meagan J McGrath
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Matthew J Eramo
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Rajendra Gurung
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Absorn Sriratana
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Stefan M Gehrig
- Centre for Muscle Research, Department of Physiology, School of Biomedical Sciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Gordon S Lynch
- Centre for Muscle Research, Department of Physiology, School of Biomedical Sciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Sonia Raveena Lourdes
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Frank Koentgen
- Ozgene Pty Ltd, Bentley, Perth, Western Australia, Australia
| | - Sandra J Feeney
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Michael Lazarou
- Neuroscience Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Catriona A McLean
- Department of Anatomical Pathology, Alfred Hospital, Prahran, Melbourne, Victoria, Australia
| | - Christina A Mitchell
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
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12
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Haapalainen AM, Daddali R, Hallman M, Rämet M. Human CPPED1 belongs to calcineurin-like metallophosphoesterase superfamily and dephosphorylates PI3K-AKT pathway component PAK4. J Cell Mol Med 2021; 25:6304-6317. [PMID: 34009729 PMCID: PMC8366450 DOI: 10.1111/jcmm.16607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 04/20/2021] [Accepted: 04/26/2021] [Indexed: 12/20/2022] Open
Abstract
Protein kinases and phosphatases regulate cellular processes by reversible phosphorylation and dephosphorylation events. CPPED1 is a recently identified serine/threonine protein phosphatase that dephosphorylates AKT1 of the PI3K-AKT signalling pathway. We previously showed that CPPED1 levels are down-regulated in the human placenta during spontaneous term birth. In this study, based on sequence comparisons, we propose that CPPED1 is a member of the class III phosphodiesterase (PDE) subfamily within the calcineurin-like metallophosphoesterase (MPE) superfamily rather than a member of the phosphoprotein phosphatase (PPP) or metal-dependent protein phosphatase (PPM) protein families. We used a human proteome microarray to identify 36 proteins that putatively interact with CPPED1. Of these, GRB2, PAK4 and PIK3R2 are known to regulate the PI3K-AKT pathway. We further confirmed CPPED1 interactions with PAK4 and PIK3R2 by coimmunoprecipitation analyses. We characterized the effect of CPPED1 on phosphorylation of PAK4 and PIK3R2 in vitro by mass spectrometry. CPPED1 dephosphorylated specific serine residues in PAK4, while phosphorylation levels in PIK3R2 remained unchanged. Our findings indicate that CPPED1 may regulate PI3K-AKT pathway activity at multiple levels. Higher CPPED1 levels may inhibit PI3K-AKT pathway maintaining pregnancy. Consequences of decreased CPPED1 expression during labour remain to be elucidated.
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Affiliation(s)
- Antti M. Haapalainen
- PEDEGO Research Unit and Medical Research Center OuluUniversity of OuluOuluFinland
- Department of Children and AdolescentsOulu University HospitalOuluFinland
| | - Ravindra Daddali
- PEDEGO Research Unit and Medical Research Center OuluUniversity of OuluOuluFinland
- Department of Children and AdolescentsOulu University HospitalOuluFinland
| | - Mikko Hallman
- PEDEGO Research Unit and Medical Research Center OuluUniversity of OuluOuluFinland
- Department of Children and AdolescentsOulu University HospitalOuluFinland
| | - Mika Rämet
- PEDEGO Research Unit and Medical Research Center OuluUniversity of OuluOuluFinland
- Department of Children and AdolescentsOulu University HospitalOuluFinland
- Faculty of Medicine and Health TechnologyTampere UniversityTampereFinland
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13
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Wang Q, Cao Z, Du B, Zhang Q, Chen L, Wang X, Yuan Z, Wang P, He R, Shan J, Zhao Y, Miao L. Membrane contact site-dependent cholesterol transport regulates Na +/K +-ATPase polarization and spermiogenesis in Caenorhabditis elegans. Dev Cell 2021; 56:1631-1645.e7. [PMID: 34051143 DOI: 10.1016/j.devcel.2021.05.002] [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: 08/10/2020] [Revised: 03/08/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Spermiogenesis in nematodes is a process whereby round and quiescent spermatids differentiate into asymmetric and crawling spermatozoa. The molecular mechanism underlying this symmetry breaking remains uncharacterized. In this study, we revealed that sperm-specific Na+/K+-ATPase (NKA) is evenly distributed on the plasma membrane (PM) of Caenorhabditis elegans spermatids but is translocated to and subsequently enters the invaginated membrane of the spermatozoa cell body during sperm activation. The polarization of NKA depends on the transport of cholesterol from the PM to membranous organelles (MOs) via membrane contact sites (MCSs). The inositol 5-phosphatase CIL-1 and the MO-localized PI4P phosphatase SAC-1 may mediate PI4P metabolism to drive cholesterol countertransport via sterol/lipid transport proteins through MCSs. Furthermore, the NKA function is required for C. elegans sperm motility and reproductive success. Our data imply that the lipid dynamics mediated by MCSs might play crucial roles in the establishment of cell polarity. eGraphical abstract.
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Affiliation(s)
- Qiushi Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Cao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Baochen Du
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Zhang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lianwan Chen
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xia Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhiheng Yuan
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruijun He
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jin Shan
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanmei Zhao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Long Miao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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14
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Sicking M, Lang S, Bochen F, Roos A, Drenth JPH, Zakaria M, Zimmermann R, Linxweiler M. Complexity and Specificity of Sec61-Channelopathies: Human Diseases Affecting Gating of the Sec61 Complex. Cells 2021; 10:1036. [PMID: 33925740 PMCID: PMC8147068 DOI: 10.3390/cells10051036] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/15/2021] [Accepted: 04/17/2021] [Indexed: 12/14/2022] Open
Abstract
The rough endoplasmic reticulum (ER) of nucleated human cells has crucial functions in protein biogenesis, calcium (Ca2+) homeostasis, and signal transduction. Among the roughly one hundred components, which are involved in protein import and protein folding or assembly, two components stand out: The Sec61 complex and BiP. The Sec61 complex in the ER membrane represents the major entry point for precursor polypeptides into the membrane or lumen of the ER and provides a conduit for Ca2+ ions from the ER lumen to the cytosol. The second component, the Hsp70-type molecular chaperone immunoglobulin heavy chain binding protein, short BiP, plays central roles in protein folding and assembly (hence its name), protein import, cellular Ca2+ homeostasis, and various intracellular signal transduction pathways. For the purpose of this review, we focus on these two components, their relevant allosteric effectors and on the question of how their respective functional cycles are linked in order to reconcile the apparently contradictory features of the ER membrane, selective permeability for precursor polypeptides, and impermeability for Ca2+. The key issues are that the Sec61 complex exists in two conformations: An open and a closed state that are in a dynamic equilibrium with each other, and that BiP contributes to its gating in both directions in cooperation with different co-chaperones. While the open Sec61 complex forms an aqueous polypeptide-conducting- and transiently Ca2+-permeable channel, the closed complex is impermeable even to Ca2+. Therefore, we discuss the human hereditary and tumor diseases that are linked to Sec61 channel gating, termed Sec61-channelopathies, as disturbances of selective polypeptide-impermeability and/or aberrant Ca2+-permeability.
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Affiliation(s)
- Mark Sicking
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Sven Lang
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Florian Bochen
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
| | - Andreas Roos
- Department of Neuropediatrics, Essen University Hospital, D-45147 Essen, Germany;
| | - Joost P. H. Drenth
- Department of Molecular Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Muhammad Zakaria
- Department of Genetics, Hazara University, Mansehra 21300, Pakistan;
| | - Richard Zimmermann
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Maximilian Linxweiler
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
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15
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Role of protons in calcium signaling. Biochem J 2021; 478:895-910. [PMID: 33635336 DOI: 10.1042/bcj20200971] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 02/03/2023]
Abstract
Thirty-six years after the publication of the important article by Busa and Nuccitelli on the variability of intracellular pH (pHi) and the interdependence of pHi and intracellular Ca2+ concentration ([Ca2+]i), little research has been carried out on pHi and calcium signaling. Moreover, the results appear to be contradictory. Some authors claim that the increase in [Ca2+]i is due to a reduction in pHi, others that it is caused by an increase in pHi. The reasons for these conflicting results have not yet been discussed and clarified in an exhaustive manner. The idea that variations in pHi are insignificant, because cellular buffers quickly stabilize the pHi, may be a limiting and fundamentally wrong concept. In fact, it has been shown that protons can move and react in the cell before they are neutralized. Variations in pHi have a remarkable impact on [Ca2+]i and hence on some of the basic biochemical mechanisms of calcium signaling. This paper focuses on the possible triggering role of protons during their short cellular cycle and it suggests a new hypothesis for an IP3 proton dependent mechanism of action.
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16
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Schurmans S, Vande Catsyne CA, Desmet C, Moës B. The phosphoinositide 5-phosphatase INPP5K: From gene structure to in vivo functions. Adv Biol Regul 2021; 79:100760. [PMID: 33060052 DOI: 10.1016/j.jbior.2020.100760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/05/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
INPP5K (Inositol Polyphosphate 5-Phosphatase K, or SKIP (for Skeletal muscle and Kidney enriched Inositol Phosphatase) is a member of the phosphoinositide 5-phosphatases family. Its protein structure is comprised of a N-terminal catalytic domain which hydrolyses both PtdIns(4,5)P2 and PtdIns(3,4,5)P3, followed by a SKICH domain at the C-terminus which is responsible for protein-protein interactions and subcellular localization of INPP5K. Strikingly, INPP5K is mostly concentrated in the endoplasmic reticulum, although it is also detected at the plasma membrane, in the cytosol and the nucleus. Recently, mutations in INPP5K have been detected in patients with a rare form of autosomal recessive congenital muscular dystrophy with cataract, short stature and intellectual disability. INPP5K functions extend from control of insulin signaling, endoplasmic reticulum stress response and structural integrity, myoblast differentiation, cytoskeleton organization, cell adhesion and migration, renal osmoregulation, to cancer. The goal of this review is thus to summarize and comment recent and less recent data in the literature on INPP5K, in particular on the structure, expression, intracellular localization, interactions and functions of this specific member of the 5-phosphatases family.
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Affiliation(s)
- Stéphane Schurmans
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium; Secteur de Biochimie Métabolique Vétérinaire, Département des Sciences Fonctionnelles, Faculté de Médecine Vétérinaire, Building B42, Université de Liège, Quartier Vallée 2, Avenue de Cureghem 7A-7D, 4000-Liège, Belgium.
| | - Charles-Andrew Vande Catsyne
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
| | - Christophe Desmet
- Laboratory of Cellular and Molecular Immunology, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
| | - Bastien Moës
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
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17
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Paesmans J, Martin E, Deckers B, Berghmans M, Sethi R, Loeys Y, Pardon E, Steyaert J, Verstreken P, Galicia C, Versées W. A structure of substrate-bound Synaptojanin1 provides new insights in its mechanism and the effect of disease mutations. eLife 2020; 9:64922. [PMID: 33349335 PMCID: PMC7781601 DOI: 10.7554/elife.64922] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/16/2020] [Indexed: 12/13/2022] Open
Abstract
Synaptojanin1 (Synj1) is a phosphoinositide phosphatase, important in clathrin uncoating during endocytosis of presynaptic vesicles. It was identified as a potential drug target for Alzheimer's disease, Down syndrome, and TBC1D24-associated epilepsy, while also loss-of-function mutations in Synj1 are associated with epilepsy and Parkinson's disease. Despite its involvement in a range of disorders, structural, and detailed mechanistic information regarding the enzyme is lacking. Here, we report the crystal structure of the 5-phosphatase domain of Synj1. Moreover, we also present a structure of this domain bound to the substrate diC8-PI(3,4,5)P3, providing the first image of a 5-phosphatase with a trapped substrate in its active site. Together with an analysis of the contribution of the different inositide phosphate groups to catalysis, these structures provide new insights in the Synj1 mechanism. Finally, we analysed the effect of three clinical missense mutations (Y793C, R800C, Y849C) on catalysis, unveiling the molecular mechanisms underlying Synj1-associated disease.
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Affiliation(s)
- Jone Paesmans
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ella Martin
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Babette Deckers
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Marjolijn Berghmans
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ritika Sethi
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Yannick Loeys
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Els Pardon
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jan Steyaert
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium.,KU Leuven, Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Christian Galicia
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Wim Versées
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
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18
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Csolle MP, Ooms LM, Papa A, Mitchell CA. PTEN and Other PtdIns(3,4,5)P 3 Lipid Phosphatases in Breast Cancer. Int J Mol Sci 2020; 21:ijms21239189. [PMID: 33276499 PMCID: PMC7730566 DOI: 10.3390/ijms21239189] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/31/2022] Open
Abstract
The phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is hyperactivated in ~70% of breast cancers. Class I PI3K generates PtdIns(3,4,5)P3 at the plasma membrane in response to growth factor stimulation, leading to AKT activation to drive cell proliferation, survival and migration. PTEN negatively regulates PI3K/AKT signalling by dephosphorylating PtdIns(3,4,5)P3 to form PtdIns(4,5)P2. PtdIns(3,4,5)P3 can also be hydrolysed by the inositol polyphosphate 5-phosphatases (5-phosphatases) to produce PtdIns(3,4)P2. Interestingly, while PTEN is a bona fide tumour suppressor and is frequently mutated/lost in breast cancer, 5-phosphatases such as PIPP, SHIP2 and SYNJ2, have demonstrated more diverse roles in regulating mammary tumourigenesis. Reduced PIPP expression is associated with triple negative breast cancers and reduced relapse-free and overall survival. Although PIPP depletion enhances AKT phosphorylation and supports tumour growth, this also inhibits cell migration and metastasis in vivo, in a breast cancer oncogene-driven murine model. Paradoxically, SHIP2 and SYNJ2 are increased in primary breast tumours, which correlates with invasive disease and reduced survival. SHIP2 or SYNJ2 overexpression promotes breast tumourigenesis via AKT-dependent and independent mechanisms. This review will discuss how PTEN, PIPP, SHIP2 and SYNJ2 distinctly regulate multiple functional targets, and the mechanisms by which dysregulation of these distinct phosphoinositide phosphatases differentially affect breast cancer progression.
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19
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D'Amico A, Fattori F, Nicita F, Barresi S, Tasca G, Verardo M, Pizzi S, Moroni I, De Mitri F, Frongia A, Pane M, Mercuri E, Tartaglia M, Bertini E. A Recurrent Pathogenic Variant of INPP5K Underlies Autosomal Recessive Congenital Muscular Dystrophy With Cataracts and Intellectual Disability: Evidence for a Founder Effect in Southern Italy. Front Genet 2020; 11:565868. [PMID: 33193651 PMCID: PMC7530278 DOI: 10.3389/fgene.2020.565868] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/18/2020] [Indexed: 01/04/2023] Open
Abstract
Inositol polyphosphate-5-phosphatase K [INPP5K (MIM: 607875)] acts as a PIP3 5-phosphatase and regulates actin cytoskeleton, insulin, and cell migration. Biallelic pathogenic variants in INPP5K have recently been reported in patients affected by a form of muscular dystrophy with childhood onset. Affected patients have limb girdle muscle weakness, often associated with bilateral cataracts, short stature, and intellectual disability. Here we report four patients affected by INPP5K-related muscle dystrophy, who were apparently unrelated but originated from the same geographical area in South Italy. These patients manifest a recognizable phenotype characterized by early onset muscular dystrophy associated with short stature and intellectual disability. All affected subjects were homozygous or compound heterozygous for the c.67G > A (p.Val23Met) missense change and shared a common haplotype, indicating the occurrence of a founder effect.
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Affiliation(s)
- Adele D'Amico
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Fabiana Fattori
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Francesco Nicita
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Sabina Barresi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Giorgio Tasca
- Unità Operativa Complessa di Neurologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Margherita Verardo
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Simone Pizzi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Isabella Moroni
- Child Neurology Unit, Foundation IRCCS Neurological Institute "C. Besta", Milan, Italy
| | - Francesca De Mitri
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Annalia Frongia
- Pediatric Neurology Unit, Catholic University and Nemo Center, Rome, Italy
| | - Marika Pane
- Pediatric Neurology Unit, Catholic University and Nemo Center, Rome, Italy
| | - Eugenio Mercuri
- Pediatric Neurology Unit, Catholic University and Nemo Center, Rome, Italy
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
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20
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The Prediction and Prognostic Significance of INPP5K Expression in Patients with Liver Cancer. BIOMED RESEARCH INTERNATIONAL 2020; 2020:9519235. [PMID: 32420386 PMCID: PMC7201693 DOI: 10.1155/2020/9519235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 03/04/2020] [Accepted: 03/13/2020] [Indexed: 02/06/2023]
Abstract
Liver cancer is a devastating disease for humans with poor prognosis. Although the survival rate of patients with liver cancer has improved in the past decades, the recurrence and metastasis of liver cancer are still obstacles for us. Inositol polyphosphate-5-phosphatase K (INPP5K) belongs to the family of phosphoinositide 5-phosphatases (PI 5-phosphatases), which have been reported to be associated with cell migration, polarity, adhesion, and cell invasion, especially in cancers. However, there have been few studies on the correlation of INPP5K and liver cancer. In this study, we explored the prognostic significance of INPP5K in liver cancer through bioinformatics analysis of data collected from The Cancer Genome Atlas (TCGA) database. Chi-square and Fisher exact tests were used to evaluate the relationship between INPP5K expression and clinical characteristics. Our results showed that low INPP5K expression was correlated with poor outcomes in liver cancer patients. Univariate and multivariate Cox analyses demonstrated that low INPP5K mRNA expression played a significant role in shortening overall survival (OS) and relapse-free survival (RFS), which might serve as the useful biomarker and prognostic factor for liver cancer. In conclusion, low INPP5K mRNA expression is an independent risk factor for poor prognosis in liver cancer.
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21
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Ramos AR, Ghosh S, Suhel T, Chevalier C, Obeng EO, Fafilek B, Krejci P, Beck B, Erneux C. Phosphoinositide 5-phosphatases SKIP and SHIP2 in ruffles, the endoplasmic reticulum and the nucleus: An update. Adv Biol Regul 2019; 75:100660. [PMID: 31628071 DOI: 10.1016/j.jbior.2019.100660] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/18/2019] [Accepted: 09/30/2019] [Indexed: 01/22/2023]
Abstract
Phosphoinositides (PIs) are phosphorylated derivatives of phosphatidylinositol. They act as signaling molecules linked to essential cellular mechanisms in eukaryotic cells, such as cytoskeleton organization, mitosis, polarity, migration or invasion. PIs are phosphorylated and dephosphorylated by a large number of PI kinases and PI phosphatases acting at the 5-, 4- and 3- position of the inositol ring. PI 5-phosphatases i.e. OCRL, INPP5B, SHIP1/2, Synaptojanin 1/2, INPP5E, INPP5J, SKIP (INPP5K) are enzymes that dephosphorylate the 5-phosphate position of PIs. Several human genetic diseases such as the Lowe syndrome, some congenital muscular dystrophy and opsismodysplasia are due to mutations in PI phosphatases, resulting in loss-of-function. The PI phosphatases are also up or down regulated in several human cancers such as glioblastoma or breast cancer. Their cellular localization, that is dynamic and varies in response to stimuli, is an important issue to understand function. This is the case for two members of the PI 5-phosphatase SKIP and SHIP2. Both enzymes are in ruffles, plasma membranes, the endoplasmic reticulum, a situation that is unique for SKIP, and the nucleus. Following localization, PI 5-phosphatases act on specific cellular pools of PIs, which in turn interact with target proteins. Nuclear PIs have emerged as regulators of genome functions in different area of cell signaling. They often localize to nuclear speckles, as do several PI metabolizing kinases and phosphatases. We asked whether SKIP and SHIP2 could have an impact on nuclear PI(4,5)P2. In two glioblastoma cell models, lowering SKIP expression had an impact on nuclear PI(4,5)P2. In a model of SHIP2 deletion in MCF-7 cells, no change in nuclear PI(4,5)P2 was observed. Finally, we present evidence of an anti-tumoral role of SKIP in vivo, in xenografts using as model U87shSKIP cells.
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Affiliation(s)
- Ana Raquel Ramos
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Somadri Ghosh
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Tara Suhel
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Clément Chevalier
- Center for Microscopy and Molecular Imaging ULB, 12 Rue des Professeurs Jeener et Brachet, 6041, Charleroi, Belgium
| | - Eric Owusu Obeng
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium; Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, 40126, Bologna, Italy
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Benjamin Beck
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Christophe Erneux
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium.
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22
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Ramos AR, Ghosh S, Erneux C. The impact of phosphoinositide 5-phosphatases on phosphoinositides in cell function and human disease. J Lipid Res 2018; 60:276-286. [PMID: 30194087 DOI: 10.1194/jlr.r087908] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/01/2018] [Indexed: 02/06/2023] Open
Abstract
Phosphoinositides (PIs) are recognized as major signaling molecules in many different functions of eukaryotic cells. PIs can be dephosphorylated by multiple phosphatase activities at the 5-, 4-, and 3- positions. Human PI 5-phosphatases belong to a family of 10 members. Except for inositol polyphosphate 5-phosphatase A, they all catalyze the dephosphorylation of PI(4,5)P2 and/or PI(3,4,5)P3 at the 5- position. PI 5-phosphatases thus directly control the levels of PI(3,4,5)P3 and participate in the fine-tuning regulatory mechanisms of PI(3,4)P2 and PI(4,5)P2 Second messenger functions have been demonstrated for PI(3,4)P2 in invadopodium maturation and lamellipodia formation. PI 5-phosphatases can use several substrates on isolated enzymes, and it has been challenging to establish their real substrate in vivo. PI(4,5)P2 has multiple functions in signaling, including interacting with scaffold proteins, ion channels, and cytoskeleton proteins. PI 5-phosphatase isoenzymes have been individually implicated in human diseases, such as the oculocerebrorenal syndrome of Lowe, through mechanisms that include lipid control. Oncogenic and tumor-suppressive functions of PI 5-phosphatases have also been reported in different cell contexts. The mechanisms responsible for genetic diseases and for oncogenic or tumor-suppressive functions are not fully understood. The regulation of PI 5-phosphatases is thus crucial in understanding cell functions.
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Affiliation(s)
- Ana Raquel Ramos
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Somadri Ghosh
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Christophe Erneux
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
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23
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Dong R, Zhu T, Benedetti L, Gowrishankar S, Deng H, Cai Y, Wang X, Shen K, De Camilli P. The inositol 5-phosphatase INPP5K participates in the fine control of ER organization. J Cell Biol 2018; 217:3577-3592. [PMID: 30087126 PMCID: PMC6168264 DOI: 10.1083/jcb.201802125] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/26/2018] [Accepted: 07/11/2018] [Indexed: 12/19/2022] Open
Abstract
Endoplasmic reticulum (ER) morphology is dynamic and key to its function during different cellular processes. Dong et al. now show in convergent studies in human cells and Caenorhabditis elegans neurons that a phosphoinositide phosphatase (INPP5K) is localized on the surface of the ER network and helps control the shape of the ER. INPP5K (SKIP) is an inositol 5-phosphatase that localizes in part to the endoplasmic reticulum (ER). We show that recruitment of INPP5K to the ER is mediated by ARL6IP1, which shares features of ER-shaping proteins. Like ARL6IP1, INPP5K is preferentially localized in ER tubules and enriched, relative to other ER resident proteins (Sec61β, VAPB, and Sac1), in newly formed tubules that grow along microtubule tracks. Depletion of either INPP5K or ARL6IP1 results in the increase of ER sheets. In a convergent but independent study, a screen for mutations affecting the distribution of the ER network in dendrites of the PVD neurons of Caenorhabditis elegans led to the isolation of mutants in CIL-1, which encodes the INPP5K worm orthologue. The mutant phenotype was rescued by expression of wild type, but not of catalytically inactive CIL-1. Our results reveal an unexpected role of an ER localized polyphosphoinositide phosphatase in the fine control of ER network organization.
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Affiliation(s)
- Rui Dong
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Ting Zhu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lorena Benedetti
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Swetha Gowrishankar
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Huichao Deng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yiying Cai
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Xiangming Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Kang Shen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China .,University of Chinese Academy of Sciences, Beijing, China.,Department of Biology, Stanford University School of Medicine, Stanford, CA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Pietro De Camilli
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT .,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT.,Kavli Institute for Neurosciences, Yale University School of Medicine, New Haven, CT
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24
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Yousaf S, Sheikh SA, Riazuddin S, Waryah AM, Ahmed ZM. INPP5K variant causes autosomal recessive congenital cataract in a Pakistani family. Clin Genet 2018; 93:682-686. [PMID: 28940338 DOI: 10.1111/cge.13143] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/09/2017] [Accepted: 09/17/2017] [Indexed: 11/30/2022]
Abstract
Congenital cataract (CC) is clinically and genetically highly heterogeneous. Here, we enrolled a consanguineous kindred (LUCC15) from Pakistan, with 3 affected individuals suffering with CC. Exome sequencing revealed a transition mutation [c.149 T > C; p.(Ile50Thr)] in INPP5K. Inositol polyphosphate-5-phosphatase K, encoded by INPP5K, is involved in dephosphorylation of phosphatidylinositol (PtdIns) 4,5-bisphosphate, and PtdIns 3,4,5-trisphosphate. Recently, pathogenic variants in INPP5K have been reported in families with congenital muscular dystrophies, intellectual disability, and cataract. In our family LUCC15, mild to moderate intellectual disability along with speech impairment was observed in 2 affected individuals. Magnetic resonance imaging of brain and muscles tissues did not reveal any cerebellar or muscular atrophy. However, electromyography of both upper and lower limbs revealed irritable myopathy. Comparison of clinical phenotype of all the known affected individuals, including LUCC15 family, homozygous for INPP5K alleles revealed reduced penetrance of muscular dystrophy and intellectual disability. Similarly, skeletal muscle abnormalities were highly variable among inpp5ka zebrafish mutants analyzed in this study. These phenotypic variabilities may be due to epigenetic factors and/or genetic modifiers.
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Affiliation(s)
- S Yousaf
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine University of Maryland, Baltimore, Maryland
| | - S A Sheikh
- Molecular Biology & Genetics Department, Liaquat University of Medical & Health Sciences, Jamshoro, Pakistan
| | - S Riazuddin
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine University of Maryland, Baltimore, Maryland
| | - A M Waryah
- Molecular Biology & Genetics Department, Liaquat University of Medical & Health Sciences, Jamshoro, Pakistan
| | - Z M Ahmed
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine University of Maryland, Baltimore, Maryland
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25
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Ramos AR, Elong Edimo W, Erneux C. Phosphoinositide 5-phosphatase activities control cell motility in glioblastoma: Two phosphoinositides PI(4,5)P2 and PI(3,4)P2 are involved. Adv Biol Regul 2018; 67:40-48. [PMID: 28916189 DOI: 10.1016/j.jbior.2017.09.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/01/2017] [Accepted: 09/01/2017] [Indexed: 05/15/2023]
Abstract
Inositol polyphosphate 5-phosphatases or phosphoinositide 5-phosphatases (PI 5-phosphatases) are enzymes that can act on soluble inositol phosphates and/or phosphoinositides (PIs). Several PI 5-phosphatases have been linked to human genetic diseases, in particular the Lowe protein or OCRL which is mutated in the Lowe syndrome. There are 10 different members of this family and 9 of them can use PIs as substrate. One of these substrates, PI(3,4,5)P3 binds to specific PH domains and recruits as effectors specific proteins to signaling complexes. Protein kinase B is one target protein and activation of the kinase will have a major impact on cell proliferation, survival and cell metabolism. Two other PIs, PI(4,5)P2 and PI(3,4)P2, are produced or used as substrates of PI 5-phosphatases (OCRL, INPP5B, SHIP1/2, SYNJ1/2, INPP5K, INPP5J, INPP5E). The inositol lipids may influence many aspects of cytoskeletal organization, lamellipodia formation and F-actin polymerization. PI 5-phosphatases have been reported to control cell migration, adhesion, polarity and cell invasion particularly in cancer cells. In glioblastoma, reducing SHIP2 expression can positively or negatively affect the speed of cell migration depending on the glioblastoma cell type. The two PI 5-phosphatases SHIP2 or SKIP could be localized at the plasma membrane and can reduce either PI(3,4,5)P3 or PI(4,5)P2 abundance. In the glioblastoma 1321 N1 cells, SHIP2 controls plasma membrane PI(4,5)P2 thereby participating in the control of cell migration.
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Affiliation(s)
- Ana Raquel Ramos
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium
| | - William's Elong Edimo
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium
| | - Christophe Erneux
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium.
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26
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Wiessner M, Roos A, Munn CJ, Viswanathan R, Whyte T, Cox D, Schoser B, Sewry C, Roper H, Phadke R, Marini Bettolo C, Barresi R, Charlton R, Bönnemann CG, Abath Neto O, Reed UC, Zanoteli E, Araújo Martins Moreno C, Ertl-Wagner B, Stucka R, De Goede C, Borges da Silva T, Hathazi D, Dell’Aica M, Zahedi RP, Thiele S, Müller J, Kingston H, Müller S, Curtis E, Walter MC, Strom TM, Straub V, Bushby K, Muntoni F, Swan LE, Lochmüller H, Senderek J. Mutations in INPP5K, Encoding a Phosphoinositide 5-Phosphatase, Cause Congenital Muscular Dystrophy with Cataracts and Mild Cognitive Impairment. Am J Hum Genet 2017; 100:523-536. [PMID: 28190456 PMCID: PMC5339217 DOI: 10.1016/j.ajhg.2017.01.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/12/2017] [Indexed: 12/26/2022] Open
Abstract
Phosphoinositides are small phospholipids that control diverse cellular downstream signaling events. Their spatial and temporal availability is tightly regulated by a set of specific lipid kinases and phosphatases. Congenital muscular dystrophies are hereditary disorders characterized by hypotonia and weakness from birth with variable eye and central nervous system involvement. In individuals exhibiting congenital muscular dystrophy, early-onset cataracts, and mild intellectual disability but normal cranial magnetic resonance imaging, we identified bi-allelic mutations in INPP5K, encoding inositol polyphosphate-5-phosphatase K. Mutations impaired phosphatase activity toward the phosphoinositide phosphatidylinositol (4,5)-bisphosphate or altered the subcellular localization of INPP5K. Downregulation of INPP5K orthologs in zebrafish embryos disrupted muscle fiber morphology and resulted in abnormal eye development. These data link congenital muscular dystrophies to defective phosphoinositide 5-phosphatase activity that is becoming increasingly recognized for its role in mediating pivotal cellular mechanisms contributing to disease.
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27
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Osborn DPS, Pond HL, Mazaheri N, Dejardin J, Munn CJ, Mushref K, Cauley ES, Moroni I, Pasanisi MB, Sellars EA, Hill RS, Partlow JN, Willaert RK, Bharj J, Malamiri RA, Galehdari H, Shariati G, Maroofian R, Mora M, Swan LE, Voit T, Conti FJ, Jamshidi Y, Manzini MC. Mutations in INPP5K Cause a Form of Congenital Muscular Dystrophy Overlapping Marinesco-Sjögren Syndrome and Dystroglycanopathy. Am J Hum Genet 2017; 100:537-545. [PMID: 28190459 PMCID: PMC5339112 DOI: 10.1016/j.ajhg.2017.01.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/05/2017] [Indexed: 02/01/2023] Open
Abstract
Congenital muscular dystrophies display a wide phenotypic and genetic heterogeneity. The combination of clinical, biochemical, and molecular genetic findings must be considered to obtain the precise diagnosis and provide appropriate genetic counselling. Here we report five individuals from four families presenting with variable clinical features including muscular dystrophy with a reduction in dystroglycan glycosylation, short stature, intellectual disability, and cataracts, overlapping both the dystroglycanopathies and Marinesco-Sjögren syndrome. Whole-exome sequencing revealed homozygous missense and compound heterozygous mutations in INPP5K in the affected members of each family. INPP5K encodes the inositol polyphosphate-5-phosphatase K, also known as SKIP (skeletal muscle and kidney enriched inositol phosphatase), which is highly expressed in the brain and muscle. INPP5K localizes to both the endoplasmic reticulum and to actin ruffles in the cytoplasm. It has been shown to regulate myoblast differentiation and has also been implicated in protein processing through its interaction with the ER chaperone HSPA5/BiP. We show that morpholino-mediated inpp5k loss of function in the zebrafish results in shortened body axis, microphthalmia with disorganized lens, microcephaly, reduced touch-evoked motility, and highly disorganized myofibers. Altogether these data demonstrate that mutations in INPP5K cause a congenital muscular dystrophy syndrome with short stature, cataracts, and intellectual disability.
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Affiliation(s)
- Daniel P S Osborn
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Heather L Pond
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Neda Mazaheri
- Department of Genetics, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran; Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran
| | - Jeremy Dejardin
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Christopher J Munn
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Khaloob Mushref
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Edmund S Cauley
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Isabella Moroni
- Pediatric Neurology Unit, Fondazione IRCCS Istituto Neurologico C. Besta, 20133 Milan, Italy
| | - Maria Barbara Pasanisi
- Pediatric Neurology Unit, Fondazione IRCCS Istituto Neurologico C. Besta, 20133 Milan, Italy; Division of Neuromuscular Diseases and Neuroimmunology, Fondazione IRCCS Istituto Neurologico C. Besta, 20126 Milan, Italy
| | - Elizabeth A Sellars
- Department of Pediatrics, Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR 72202, USA
| | - R Sean Hill
- Program in Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jennifer N Partlow
- Program in Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | | | - Jaipreet Bharj
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Reza Azizi Malamiri
- Department of Paediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6163764648, Iran
| | - Hamid Galehdari
- Department of Genetics, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran; Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran
| | - Gholamreza Shariati
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran; Department of Medical Genetics, Faculty of Medicine, Ahvaz Jundishapur, University of Medical Sciences, Ahvaz 6135715794, Iran
| | - Reza Maroofian
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK; University of Exeter Medical School, RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Exeter EX1 2LU, UK
| | - Marina Mora
- Division of Neuromuscular Diseases and Neuroimmunology, Fondazione IRCCS Istituto Neurologico C. Besta, 20126 Milan, Italy
| | - Laura E Swan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Thomas Voit
- NIHR GOSH Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Francesco J Conti
- NIHR GOSH Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Yalda Jamshidi
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK.
| | - M Chiara Manzini
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA.
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28
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Hakim S, Dyson JM, Feeney SJ, Davies EM, Sriratana A, Koenig MN, Plotnikova OV, Smyth IM, Ricardo SD, Hobbs RM, Mitchell CA. Inpp5e suppresses polycystic kidney disease via inhibition of PI3K/Akt-dependent mTORC1 signaling. Hum Mol Genet 2016; 25:2295-2313. [PMID: 27056978 DOI: 10.1093/hmg/ddw097] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 03/17/2016] [Indexed: 12/20/2022] Open
Abstract
Polycystic kidney disease (PKD) is a common cause of renal failure with few effective treatments. INPP5E is an inositol polyphosphate 5-phosphatase that dephosphorylates phosphoinositide 3-kinase (PI3K)-generated PI(3,4,5)P3 and is mutated in ciliopathy syndromes. Germline Inpp5e deletion is embryonically lethal, attributed to cilia stability defects, and is associated with polycystic kidneys. However, the molecular mechanisms responsible for PKD development upon Inpp5e loss remain unknown. Here, we show conditional inactivation of Inpp5e in mouse kidney epithelium results in severe PKD and renal failure, associated with a partial reduction in cilia number and hyperactivation of PI3K/Akt and downstream mammalian target of rapamycin complex 1 (mTORC1) signaling. Treatment with an mTORC1 inhibitor improved kidney morphology and function, but did not affect cilia number or length. Therefore, we identify Inpp5e as an essential inhibitor of the PI3K/Akt/mTORC1 signaling axis in renal epithelial cells, and demonstrate a critical role for Inpp5e-dependent mTORC1 regulation in PKD suppression.
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Affiliation(s)
- Sandra Hakim
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Jennifer M Dyson
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Sandra J Feeney
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Elizabeth M Davies
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Absorn Sriratana
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Monica N Koenig
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Olga V Plotnikova
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Ian M Smyth
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia Development and Stem Cell program, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia
| | - Sharon D Ricardo
- Development and Stem Cell program, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia
| | - Robin M Hobbs
- Development and Stem Cell program, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC 3800, Australia Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia
| | - Christina A Mitchell
- Cancer Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
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29
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Regulation of PtdIns(3,4,5)P3/Akt signalling by inositol polyphosphate 5-phosphatases. Biochem Soc Trans 2016; 44:240-52. [DOI: 10.1042/bst20150214] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The phosphoinositide 3-kinase (PI3K) generated lipid signals, PtdIns(3,4,5)P3 and PtdIns(3,4)P2, are both required for the maximal activation of the serine/threonine kinase proto-oncogene Akt. The inositol polyphosphate 5-phosphatases (5-phosphatases) hydrolyse the 5-position phosphate from the inositol head group of PtdIns(3,4,5)P3 to yield PtdIns(3,4)P2. Extensive work has revealed several 5-phosphatases inhibit PI3K-driven Akt signalling, by decreasing PtdIns(3,4,5)P3 despite increasing cellular levels of PtdIns(3,4)P2. The roles that 5-phosphatases play in suppressing cell proliferation and transformation are slow to emerge; however, the 5-phosphatase PIPP [proline-rich inositol polyphosphate 5-phosphatase; inositol polyphosphate 5-phosphatase (INPP5J)] has recently been identified as a putative tumour suppressor in melanoma and breast cancer and SHIP1 [SH2 (Src homology 2)-containing inositol phosphatase 1] inhibits haematopoietic cell proliferation. INPP5E regulates cilia stability and INPP5E mutations have been implicated ciliopathy syndromes. This review will examine 5-phosphatase regulation of PI3K/Akt signalling, focussing on the role PtdIns(3,4,5)P3 5-phosphatases play in developmental diseases and cancer.
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30
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Piscatelli HL, Li M, Zhou D. Dual 4- and 5-phosphatase activities regulate SopB-dependent phosphoinositide dynamics to promote bacterial entry. Cell Microbiol 2015; 18:705-19. [PMID: 26537021 DOI: 10.1111/cmi.12542] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 10/21/2015] [Accepted: 10/24/2015] [Indexed: 12/16/2022]
Abstract
Salmonella are able to invade non-phagocytic cells such as intestinal epithelial cells by modulating the host actin cytoskeleton to produce membrane ruffles. Two type III effector proteins SopB and SopE play key roles to this modulation. SopE is a known guanine nucleotide exchange factor (GEF) capable of activating Rac1 and CDC42. SopB is a phosphatidylinositol 4-phosphatase and 5-phosphatase promoting membrane ruffles and invasion of Salmonella through undefined mechanisms. Previous studies have demonstrated that the 4-phosphatase activity of SopB is required for PtdIns-3-phosphate (PtdIns(3)P) accumulation and SopB-mediated invasion. We show here that both the 4-phosphatase as well as the 5-phosphatase activities of SopB are essential in ruffle formation and subsequent invasion. We found that the 5-phosphatase activity of SopB is likely responsible for generating PtdIns-3,4-bisphosphate (PtdIns(3,4)P(2)) and subsequent recruitment of sorting nexin 9 (SNX9), an actin modulating protein. Intriguingly, the 4-phosphatase activity is responsible for the dephosphorylation of PtdIns(3,4)P(2) into PtdIns(3)P. Alone, neither activity is sufficient for ruffling but when acting in conjunction with one another, the 4-phosphatase and 5-phosphatase activities led to SNX9-mediated ruffling and Salmonella invasion. This work reveals the unique ability of bacterial effector protein SopB to utilize both its 4- and 5-phosphatase activities to regulate phosphoinositide dynamics to promote bacterial entry.
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Affiliation(s)
- Heather L Piscatelli
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Menghan Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Daoguo Zhou
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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31
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Ijuin T, Hatano N, Hosooka T, Takenawa T. Regulation of insulin signaling in skeletal muscle by PIP3 phosphatase, SKIP, and endoplasmic reticulum molecular chaperone glucose-regulated protein 78. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3192-201. [DOI: 10.1016/j.bbamcr.2015.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/30/2022]
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Phosphatidylinositol 3,4,5-Trisphosphate Phosphatase SKIP Links Endoplasmic Reticulum Stress in Skeletal Muscle to Insulin Resistance. Mol Cell Biol 2015; 36:108-18. [PMID: 26483413 DOI: 10.1128/mcb.00921-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 11/20/2022] Open
Abstract
Insulin resistance is critical in the pathogenesis of type 2 diabetes. Endoplasmic reticulum (ER) stress in liver and adipose tissues plays an important role in the development of insulin resistance. Although skeletal muscle is a primary site for insulin-dependent glucose disposal, it is unclear if ER stress in those tissues contributes to insulin resistance. In this study, we show that skeletal muscle kidney-enriched inositol polyphosphate phosphatase (SKIP), a PIP3 (phosphatidylinositol-3,4,5-trisphosphate) phosphatase, links ER stress to insulin resistance in skeletal muscle. SKIP expression was increased due to ER stress and was higher in the skeletal muscle isolated from high-fat-diet-fed mice and db/db mice than in that from wild-type mice. Mechanistically, ER stress promotes activating transcription factor 6 (ATF6) and X-box binding protein 1 (XBP1)-dependent expression of SKIP. These findings underscore the specific and prominent role of SKIP in the development of insulin resistance in skeletal muscle.
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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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Hsu F, Mao Y. The structure of phosphoinositide phosphatases: Insights into substrate specificity and catalysis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:698-710. [PMID: 25264170 DOI: 10.1016/j.bbalip.2014.09.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/10/2014] [Accepted: 09/17/2014] [Indexed: 12/17/2022]
Abstract
Phosphoinositides (PIs) are a group of key signaling and structural lipid molecules involved in a myriad of cellular processes. PI phosphatases, together with PI kinases, are responsible for the conversion of PIs between distinctive phosphorylation states. PI phosphatases are a large collection of enzymes that are evolved from at least two disparate ancestors. One group is distantly related to endonucleases, which apply divalent metal ions for phosphoryl transfer. The other group is related to protein tyrosine phosphatases, which contain a highly conserved active site motif Cys-X5-Arg (CX5R). In this review, we focus on structural insights to illustrate current understandings of the molecular mechanisms of each PI phosphatase family, with emphasis on their structural basis for substrate specificity determinants and catalytic mechanisms. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- FoSheng Hsu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Yuxin Mao
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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35
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Differential SKIP expression in PTEN-deficient glioblastoma regulates cellular proliferation and migration. Oncogene 2014; 34:3711-27. [DOI: 10.1038/onc.2014.303] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 07/18/2014] [Accepted: 08/13/2014] [Indexed: 12/25/2022]
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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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Abstract
p21-Activated protein kinases (PAKs) are centrally involved in a plethora of cellular processes and functions. Their function as effectors of small GTPases Rac1 and Cdc42 has been extensively studied during the past two decades, particularly in the realms of cell proliferation, apoptosis, and hence tumorigenesis, as well as cytoskeletal remodeling and related cellular events in health and disease. In recent years, a large number of studies have shed light onto the fundamental role of group I PAKs, most notably PAK1, in metabolic homeostasis. In skeletal muscle, PAK1 was shown to mediate the function of insulin on stimulating GLUT4 translocation and glucose uptake, while in pancreatic β-cells, PAK1 participates in insulin granule localization and vesicle release. Furthermore, we demonstrated that PAK1 mediates the cross talk between insulin and Wnt/β-catenin signaling pathways and hence regulates gut proglucagon gene expression and the production of the incretin hormone glucagon-like peptide-1 (GLP-1). The utilization of chemical inhibitors of PAK and the characterization of Pak1(-/-) mice enabled us to gain mechanistic insights as well as to assess the overall contribution of PAKs in metabolic homeostasis. This review summarizes our current understanding of PAKs, with an emphasis on the emerging roles of PAK1 in glucose homeostasis.
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Bertelli DF, Coope A, Caricilli AM, Prada PO, Saad MJ, Velloso LA, Araujo EP. Inhibition of 72 kDa inositol polyphosphate 5-phosphatase E improves insulin signal transduction in diet-induced obesity. J Endocrinol 2013; 217:131-40. [PMID: 23349329 DOI: 10.1530/joe-12-0562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The 72 kDa inositol polyphosphate 5-phosphatase E (72k-5ptase) controls signal transduction through the catalytic dephosphorylation of the 5-position of membrane-bound phosphoinositides. The reduction of 72k-5ptase expression in the hypothalamus results in improved hypothalamic insulin signal transduction and reduction of food intake and body mass. Here, we evaluated the tissue distribution and the impact of obesity on the expression of 72k-5ptase in peripheral tissues of experimental animals. In addition, insulin signal transduction and action were determined in an animal model of obesity and insulin resistance treated with an antisense (AS) oligonucleotide that reduces 72k-5ptase expression. In lean Wistar rats, 72k-5ptase mRNA and protein are found in highest levels in heart, skeletal muscle, and white adipose tissue. In three distinct models of obesity, Wistar rats, Swiss mice fed on high-fat diet, and leptin-deficient ob/ob mice, the expression of 72k-5ptase is increased in skeletal muscle and adipose tissue. The treatment of obese Wistar rats with an anti-72k-5ptase AS oligonucleotide results in significant reduction of 72k-5ptase catalytic activity, which is accompanied by reduced food intake and body mass and improved insulin signal transduction and action as determined by immunoblotting and clamp studies respectively. 72k-5ptase expression is increased in obesity and its AS inhibition resulted in a significant improvement in insulin signal transduction and restoration of glucose homeostasis.
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Affiliation(s)
- Daniela F Bertelli
- Laboratory of Cell Signaling, Department of Internal Medicine, Faculty of Applied Sciences and Department of Nursing, University of Campinas, DCM-FCM, UNICAMP, 13084-970, Campinas, SP, Brazil
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Abstract
Phosphoinositide signalling molecules interact with a plethora of effector proteins to regulate cell proliferation and survival, vesicular trafficking, metabolism, actin dynamics and many other cellular functions. The generation of specific phosphoinositide species is achieved by the activity of phosphoinositide kinases and phosphatases, which phosphorylate and dephosphorylate, respectively, the inositol headgroup of phosphoinositide molecules. The phosphoinositide phosphatases can be classified as 3-, 4- and 5-phosphatases based on their specificity for dephosphorylating phosphates from specific positions on the inositol head group. The SAC phosphatases show less specificity for the position of the phosphate on the inositol ring. The phosphoinositide phosphatases regulate PI3K/Akt signalling, insulin signalling, endocytosis, vesicle trafficking, cell migration, proliferation and apoptosis. Mouse knockout models of several of the phosphoinositide phosphatases have revealed significant physiological roles for these enzymes, including the regulation of embryonic development, fertility, neurological function, the immune system and insulin sensitivity. Importantly, several phosphoinositide phosphatases have been directly associated with a range of human diseases. Genetic mutations in the 5-phosphatase INPP5E are causative of the ciliopathy syndromes Joubert and MORM, and mutations in the 5-phosphatase OCRL result in Lowe's syndrome and Dent 2 disease. Additionally, polymorphisms in the 5-phosphatase SHIP2 confer diabetes susceptibility in specific populations, whereas reduced protein expression of SHIP1 is reported in several human leukaemias. The 4-phosphatase, INPP4B, has recently been identified as a tumour suppressor in human breast and prostate cancer. Mutations in one SAC phosphatase, SAC3/FIG4, results in the degenerative neuropathy, Charcot-Marie-Tooth disease. Indeed, an understanding of the precise functions of phosphoinositide phosphatases is not only important in the context of normal human physiology, but to reveal the mechanisms by which these enzyme families are implicated in an increasing repertoire of human diseases.
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Xiong Q, Chai J, Deng C, Jiang S, Liu Y, Huang T, Suo X, Zhang N, Li X, Yang Q, Chen M, Zheng R. Characterization of porcine SKIP gene in skeletal muscle development: Polymorphisms, association analysis, expression and regulation of cell growth in C2C12 cells. Meat Sci 2012; 92:490-7. [DOI: 10.1016/j.meatsci.2012.05.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 04/02/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
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Ijuin T, Takenawa T. Role of phosphatidylinositol 3,4,5-trisphosphate (PIP3) 5-phosphatase skeletal muscle- and kidney-enriched inositol polyphosphate phosphatase (SKIP) in myoblast differentiation. J Biol Chem 2012; 287:31330-41. [PMID: 22815484 DOI: 10.1074/jbc.m112.388785] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Insulin-like growth factors (IGFs) are essential for the development, regeneration, and hypertrophy of skeletal muscles. IGF-II promotes myoblast differentiation through phosphatidylinositol 3-kinase (PI 3-kinase), Akt, and mTOR signaling. Here, we report that skeletal muscle- and kidney-enriched inositol polyphosphate phosphatase (SKIP) negatively regulates myogenesis through inhibition of IGF-II production and attenuation of the IGF-II-Akt-mTOR signaling pathway. We also demonstrate that SKIP expression, which was markedly elevated during differentiation, was controlled by MyoD in C2C12 cells. Expression of SKIP inhibited IGF-II at the transcription level. These results indicate that SKIP regulates MyoD-mediated muscle differentiation. Silencing of SKIP increased IGF-II transcription and myoblast differentiation. Furthermore, knockdown of SKIP resulted in thick myotubes with a larger number of nuclei than that in control C2C12 cells. Taken together, these data indicate that SKIP controls the IGF-II-PI 3-kinase-Akt-mTOR auto-regulation loop during myogenesis. Our findings identify SKIP as a key regulator of muscle cell differentiation.
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Affiliation(s)
- Takeshi Ijuin
- Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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42
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Regulation of insulin signaling by the phosphatidylinositol 3,4,5-triphosphate phosphatase SKIP through the scaffolding function of Pak1. Mol Cell Biol 2012; 32:3570-84. [PMID: 22751929 DOI: 10.1128/mcb.00636-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Skeletal muscle and kidney-enriched inositol polyphosphate phosphatase (SKIP) has previously been implicated in the regulation of insulin signaling in skeletal muscle. Here, we present the first report of the mechanisms by which SKIP specifically suppresses insulin signaling and the subsequent glucose uptake. Upon insulin stimulation, SKIP is translocated to the membrane ruffles, where it binds to the active form of Pak1, which mediates multiple protein complex formation with phosphatidylinositol 3,4,5-triphosphate (PIP(3)) effectors such as Akt2, PDK1, and Rac1; this leads to inactivation of these proteins. SKIP also promotes the inhibition of Rac1-dependent kinase activity and the scaffolding function of Pak1, which results in the dissociation of Akt2 and PDK1 from Pak1. Thus, specific suppression of insulin signaling is achieved via the spatiotemporal regulation of SKIP through the scaffolding function of Pak1. These interactions are the foundation of the specific and prominent role of SKIP in the regulation of insulin signaling.
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43
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Ijuin T, Takenawa T. Regulation of insulin signaling and glucose transporter 4 (GLUT4) exocytosis by phosphatidylinositol 3,4,5-trisphosphate (PIP3) phosphatase, skeletal muscle, and kidney enriched inositol polyphosphate phosphatase (SKIP). J Biol Chem 2012; 287:6991-9. [PMID: 22247557 DOI: 10.1074/jbc.m111.335539] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glucose transporter 4 (GLUT4) is responsible for glucose uptake in the skeletal muscle. Insulin-induced translocation of GLUT4 to the plasma membrane requires phosphatidylinositol 3-kinase activation-mediated generation of phosphatidylinositol 3,4,5-trisphosphate PIP(3) and subsequent activation of Akt. Previous studies suggested that skeletal muscle and kidney enriched inositol polyphosphate phosphatase (SKIP) has negative effects on the regulation of insulin signaling in the skeletal muscle cells. Here, we compared its effects on insulin signaling by selective inhibition of SKIP, SHIP2, and phosphatase and tensin homologue on chromosome 10 (PTEN) by short interfering RNA in the C2C12 myoblast cells. Suppression of SKIP significantly increased the insulin-stimulated phosphatidylinositol 3,4,5-trisphosphate levels and Akt phosphorylation. Furthermore, silencing of SKIP, but not of PTEN, increased the insulin-dependent recruitment of GLUT4 vesicles to the plasma membrane. Taken together, these results imply that SKIP negatively regulates insulin signaling and glucose uptake by inhibiting GLUT4 docking and/or fusion to the plasma membrane.
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Affiliation(s)
- Takeshi Ijuin
- Department of Lipid Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe 650-0017, Japan
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44
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Dyson JM, Fedele CG, Davies EM, Becanovic J, Mitchell CA. Phosphoinositide phosphatases: just as important as the kinases. Subcell Biochem 2012; 58:215-279. [PMID: 22403078 DOI: 10.1007/978-94-007-3012-0_7] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phosphoinositide phosphatases comprise several large enzyme families with over 35 mammalian enzymes identified to date that degrade many phosphoinositide signals. Growth factor or insulin stimulation activates the phosphoinositide 3-kinase that phosphorylates phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] to form phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)], which is rapidly dephosphorylated either by PTEN (phosphatase and tensin homologue deleted on chromosome 10) to PtdIns(4,5)P(2), or by the 5-phosphatases (inositol polyphosphate 5-phosphatases), generating PtdIns(3,4)P(2). 5-phosphatases also hydrolyze PtdIns(4,5)P(2) forming PtdIns(4)P. Ten mammalian 5-phosphatases have been identified, which regulate hematopoietic cell proliferation, synaptic vesicle recycling, insulin signaling, and embryonic development. Two 5-phosphatase genes, OCRL and INPP5E are mutated in Lowe and Joubert syndrome respectively. SHIP [SH2 (Src homology 2)-domain inositol phosphatase] 2, and SKIP (skeletal muscle- and kidney-enriched inositol phosphatase) negatively regulate insulin signaling and glucose homeostasis. SHIP2 polymorphisms are associated with a predisposition to insulin resistance. SHIP1 controls hematopoietic cell proliferation and is mutated in some leukemias. The inositol polyphosphate 4-phosphatases, INPP4A and INPP4B degrade PtdIns(3,4)P(2) to PtdIns(3)P and regulate neuroexcitatory cell death, or act as a tumor suppressor in breast cancer respectively. The Sac phosphatases degrade multiple phosphoinositides, such as PtdIns(3)P, PtdIns(4)P, PtdIns(5)P and PtdIns(3,5)P(2) to form PtdIns. Mutation in the Sac phosphatase gene, FIG4, leads to a degenerative neuropathy. Therefore the phosphatases, like the lipid kinases, play major roles in regulating cellular functions and their mutation or altered expression leads to many human diseases.
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Affiliation(s)
- Jennifer M Dyson
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, 3800, Clayton, Australia
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45
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Mak LH, Georgiades SN, Rosivatz E, Whyte GF, Mirabelli M, Vilar R, Woscholski R. A small molecule mimicking a phosphatidylinositol (4,5)-bisphosphate binding pleckstrin homology domain. ACS Chem Biol 2011; 6:1382-90. [PMID: 21958214 DOI: 10.1021/cb2003187] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inositol phospholipids have emerged as important key players in a wide variety of cellular functions. Among the seven existing inositol phospholipids, phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P(2)) has attracted much attention in recent years due to its important role in numerous cellular signaling events and regulations, which in turn impact several human diseases. This particular lipid is recognized in the cell by specific lipid binding domains, such as the Pleckstrin-homology (PH) domain, which is also employed as a tool to monitor this important lipid. Here, we describe the synthesis and biological characterization of a small molecule that mimics the PH domain as judged by its ability to bind specifically to only PI(4,5)P(2) and effectively compete with the PH domain in vitro and in a cellular environment. The binding constant of this small molecule PH domain mimetic (PHDM) was determined to be 17.6 ± 10.1 μM, similar in potency to the PH domain. Using NIH 3T3 mouse fibroblast cells we demonstrated that this compound is cell-permeable and able to modulate PI(4,5)P(2)-dependent effects in a cellular environment such as the endocytosis of the transferrin receptor, loss of mitochondria, as well as stress fiber formation. This highly PI(4,5)P(2)-specific chemical mimetic of a PH domain not only is a powerful research tool but might also be a lead compound in future drug developments targeting PI(4,5)P(2)-dependent diseases such as Lowe syndrome.
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Affiliation(s)
- Lok Hang Mak
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Savvas N. Georgiades
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Evelyn Rosivatz
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Gillian F. Whyte
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Marianna Mirabelli
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Ramon Vilar
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Rudiger Woscholski
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
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46
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The inositol Inpp5k 5-phosphatase affects osmoregulation through the vasopressin-aquaporin 2 pathway in the collecting system. Pflugers Arch 2011; 462:871-83. [DOI: 10.1007/s00424-011-1028-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 09/04/2011] [Accepted: 09/05/2011] [Indexed: 01/15/2023]
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47
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Rahman P, Huysmans RD, Wiradjaja F, Gurung R, Ooms LM, Sheffield DA, Dyson JM, Layton MJ, Sriratana A, Takada H, Tiganis T, Mitchell CA. Silencer of death domains (SODD) inhibits skeletal muscle and kidney enriched inositol 5-phosphatase (SKIP) and regulates phosphoinositide 3-kinase (PI3K)/Akt signaling to the actin cytoskeleton. J Biol Chem 2011; 286:29758-70. [PMID: 21712384 DOI: 10.1074/jbc.m111.263103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Phosphoinositide 3-kinase (PI3K) regulates cell polarity and migration by generating phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) at the leading edge of migrating cells. The serine-threonine protein kinase Akt binds to PI(3,4,5)P(3), resulting in its activation. Active Akt promotes spatially regulated actin cytoskeletal remodeling and thereby directed cell migration. The inositol polyphosphate 5-phosphatases (5-ptases) degrade PI(3,4,5)P(3) to form PI(3,4)P(2), which leads to diminished Akt activation. Several 5-ptases, including SKIP and SHIP2, inhibit actin cytoskeletal reorganization by opposing PI3K/Akt signaling. In this current study, we identify a molecular co-chaperone termed silencer of death domains (SODD/BAG4) that forms a complex with several 5-ptase family members, including SKIP, SHIP1, and SHIP2. The interaction between SODD and SKIP exerts an inhibitory effect on SKIP PI(3,4,5)P(3) 5-ptase catalytic activity and consequently enhances the recruitment of PI(3,4,5)P(3)-effectors to the plasma membrane. In contrast, SODD(-/-) mouse embryonic fibroblasts exhibit reduced Akt-Ser(473) and -Thr(308) phosphorylation following EGF stimulation, associated with increased SKIP PI(3,4,5)P(3)-5-ptase activity. SODD(-/-) mouse embryonic fibroblasts exhibit decreased EGF-stimulated F-actin stress fibers, lamellipodia, and focal adhesion complexity, a phenotype that is rescued by the expression of constitutively active Akt1. Furthermore, reduced cell migration was observed in SODD(-/-) macrophages, which express the three 5-ptases shown to interact with SODD (SKIP, SHIP1, and SHIP2). Therefore, this study identifies SODD as a novel regulator of PI3K/Akt signaling to the actin cytoskeleton.
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Affiliation(s)
- Parvin Rahman
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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48
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Xiong Q, Chai J, Zhang PP, Wu J, Jiang SW, Zheng R, Deng CY. MyoD control of SKIP expression during pig skeletal muscle development. Mol Biol Rep 2010; 38:267-74. [PMID: 20336382 DOI: 10.1007/s11033-010-0104-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 03/16/2010] [Indexed: 11/25/2022]
Abstract
Skeletal muscle and kidney enriched inositol phosphatase (SKIP) was identified as a 5'-inositol phosphatase that hydrolyzes PI(3,4,5)P3 to PI(3,4)P2 that negatively regulates insulin-induced phosphatidylinositol 3-kinase signaling in skeletal muscle. In this study, we obtained a 1575-bp mRNA sequence of porcine SKIP that included the full coding region encoding a protein of 450 amino acids. With the use of comparative mapping, we mapped this gene to SSC12 q1.3, where many QTLs affect Backfat thickness at 10th rib, carcass yield, the number of muscle fibers, and ham weight traits. As a candidate gene for growth and carcass traits, a novel single nucleotide polymorphism in exon 12 (G>A) was detected by PCR-RFLP. The results showed that the GG genotype had higher skin percentage (SP), carcass length to first spondyle (CL1), carcass length to first rib (CL2), but lower intramuscular fat (IMF) as compared with genotype AG (P<0.05), and allele G seemed to be associated with an increase in the growth trait. Porcine SKIP was expressed abundantly in skeletal muscle tissue and was transcriptionally upregulated during skeletal muscle differentiation. Analysis of the porcine SKIP promoter sequence demonstrated that MyoD was involved in regulating SKIP mRNA expression in myotubes, partly via the cis-acting elements in SKIP promoter. In summary, we suggested that SKIP might play a role in the regulation of skeletal muscle development in pigs.
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Affiliation(s)
- Q Xiong
- Agricultural Ministry Key Laboratory of Swine Breeding and Genetics & Key Laboratory of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
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Sasaki T, Takasuga S, Sasaki J, Kofuji S, Eguchi S, Yamazaki M, Suzuki A. Mammalian phosphoinositide kinases and phosphatases. Prog Lipid Res 2009; 48:307-43. [PMID: 19580826 DOI: 10.1016/j.plipres.2009.06.001] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phosphoinositides are lipids that are present in the cytoplasmic leaflet of a cell's plasma and internal membranes and play pivotal roles in the regulation of a wide variety of cellular processes. Phosphoinositides are molecularly diverse due to variable phosphorylation of the hydroxyl groups of their inositol rings. The rapid and reversible configuration of the seven known phosphoinositide species is controlled by a battery of phosphoinositide kinases and phosphoinositide phosphatases, which are thus critical for phosphoinositide isomer-specific localization and functions. Significantly, a given phosphoinositide generated by different isozymes of these phosphoinositide kinases and phosphatases can have different biological effects. In mammals, close to 50 genes encode the phosphoinositide kinases and phosphoinositide phosphatases that regulate phosphoinositide metabolism and thus allow cells to respond rapidly and effectively to ever-changing environmental cues. Understanding the distinct and overlapping functions of these phosphoinositide-metabolizing enzymes is important for our knowledge of both normal human physiology and the growing list of human diseases whose etiologies involve these proteins. This review summarizes the structural and biological properties of all the known mammalian phosphoinositide kinases and phosphoinositide phosphatases, as well as their associations with human disorders.
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Affiliation(s)
- Takehiko Sasaki
- Department of Pathology and Immunology, Akita University, Graduate School of Medicine, Akita 010-8543, Japan.
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50
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The role of the inositol polyphosphate 5-phosphatases in cellular function and human disease. Biochem J 2009; 419:29-49. [PMID: 19272022 DOI: 10.1042/bj20081673] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phosphoinositides are membrane-bound signalling molecules that regulate cell proliferation and survival, cytoskeletal reorganization and vesicular trafficking by recruiting effector proteins to cellular membranes. Growth factor or insulin stimulation induces a canonical cascade resulting in the transient phosphorylation of PtdIns(4,5)P(2) by PI3K (phosphoinositide 3-kinase) to form PtdIns(3,4,5)P(3), which is rapidly dephosphorylated either by PTEN (phosphatase and tensin homologue deleted on chromosome 10) back to PtdIns(4,5)P(2), or by the 5-ptases (inositol polyphosphate 5-phosphatases), generating PtdIns(3,4)P(2). The 5-ptases also hydrolyse PtdIns(4,5)P(2), forming PtdIns4P. Ten mammalian 5-ptases have been identified, which share a catalytic mechanism similar to that of the apurinic/apyrimidinic endonucleases. Gene-targeted deletion of 5-ptases in mice has revealed that these enzymes regulate haemopoietic cell proliferation, synaptic vesicle recycling, insulin signalling, endocytosis, vesicular trafficking and actin polymerization. Several studies have revealed that the molecular basis of Lowe's syndrome is due to mutations in the 5-ptase OCRL (oculocerebrorenal syndrome of Lowe). Futhermore, the 5-ptases SHIP [SH2 (Src homology 2)-domain-containing inositol phosphatase] 2, SKIP (skeletal muscle- and kidney-enriched inositol phosphatase) and 72-5ptase (72 kDa 5-ptase)/Type IV/Inpp5e (inositol polyphosphate 5-phosphatase E) are implicated in negatively regulating insulin signalling and glucose homoeostasis in specific tissues. SHIP2 polymorphisms are associated with a predisposition to insulin resistance. Gene profiling studies have identified changes in the expression of various 5-ptases in specific cancers. In addition, 5-ptases such as SHIP1, SHIP2 and 72-5ptase/Type IV/Inpp5e regulate macrophage phagocytosis, and SHIP1 also controls haemopoietic cell proliferation. Therefore the 5-ptases are a significant family of signal-modulating enzymes that govern a plethora of cellular functions by regulating the levels of specific phosphoinositides. Emerging studies have implicated their loss or gain of function in human disease.
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