1
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Rennie M, Lin G, Scarlata S. Multiple functions of phospholipase Cβ1 at a glance. J Cell Sci 2022; 135:276667. [PMID: 36125065 DOI: 10.1242/jcs.260282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phospholipase Cβ (PLCβ) is the main effector of the Gq family of heterotrimeric G proteins that transduces signals from hormones and neurotransmitters into Ca2+ signals. While PLCβ is critical for Ca2+ responses, recent studies have suggested that PLCβ has additional roles independent of its lipase activity. These novel functions are carried out by a cytosolic population of PLCβ that binds and inhibits the component 3 promoter of RNA-induced silencing complex (C3PO) to impact cytosolic RNA populations. Additionally, cytosolic PLCβ binds to stress granule proteins, keeping them dispersed and thus inhibiting stress granule formation. Upon activation of the Gα subunit of Gq (Gαq), cytosolic PLCβ relocalizes to the membrane, releasing C3PO and stress granule proteins, which in turn promotes activation of C3PO and RNA processing, as well as sequestration of specific transcripts into newly formed stress granules. As highlighted in this Cell Science at a Glance and the accompanying poster, the link between Gαq signaling, increased intracellular Ca2+ and changes in RNA processing impacts neuronal cell differentiation and may also affect neuronal development and dysfunction.
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Affiliation(s)
- Madison Rennie
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
| | - Guanyu Lin
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
| | - Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA
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2
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PLCB4 upregulation is associated with unfavorable prognosis in pediatric acute myeloid leukemia. Oncol Lett 2019; 18:6057-6065. [PMID: 31788080 PMCID: PMC6865073 DOI: 10.3892/ol.2019.10921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/21/2019] [Indexed: 02/07/2023] Open
Abstract
Phospholipase C (PLC) is a membrane-associated enzyme that regulates several cellular behaviors including cell motility, growth, transformation and differentiation. PLC is involved in cancer migration, invasion and drug resistance. However, the expression status and prognostic role of PLCB4 in acute myeloid leukemia (AML) remain unclear. In the present study, the complete clinical and mRNA expression data of 285 pediatric patients with de novo AML were obtained from the Therapeutically Available Research to Generate Effective Treatments database. The association between PLCB4 expression and clinical and molecular features was explored. The expression of PLCB4 was significantly higher in patients with AML who relapsed compared with those with long-term complete remission. Patients with PLCB4 upregulation had significantly lower overall survival (OS) and event free survival (EFS) rate compared with those with low PLCB4 expression. Multivariate Cox's regression analyses demonstrated that high PLCB4 expression was an independent risk factor of adverse OS (P<0.01; HR, 2.081) and EFS (P<0.01; HR, 2.130). Following stratification analysis according to transplant status in cases of first complete remission, the patients with high expression of PLCB4 had significantly lower OS and EFS rate in the chemotherapy group, but not the stem cell transplant group. Furthermore, PLCB4-associated genes were identified using Spearman's rank correlation analysis. KEGG pathway analysis revealed that PLCB4 and its associated genes were mainly involved in three potential pathways, including the Rap1 signaling pathway. Overall, the findings of the present study suggest that increased PLCB4 expression is associated with poor clinical outcome in pediatric patients with AML, and thus may represent a potential prognostic biomarker and therapeutic target for AML.
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3
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Lu G, Chang JT, Liu Z, Chen Y, Li M, Zhu JJ. Phospholipase C Beta 1: a Candidate Signature Gene for Proneural Subtype High-Grade Glioma. Mol Neurobiol 2016; 53:6511-6525. [PMID: 26614510 PMCID: PMC5085994 DOI: 10.1007/s12035-015-9518-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/28/2015] [Indexed: 01/09/2023]
Abstract
Phospholipase C beta 1 (PLCβ1) expresses in gliomas and cultured glial cells, but its expression is barely detectable in normal glial cells. We analyzed data from Gene Expression Omnibus (GEO-GDSxxx), The Cancer Genome Atlas (TCGA), and the Repository for Molecular Brain Neoplasia Data (REMBRANDT) to explore the potential role of PLCβ1 as a biomarker in high-grade glioma (HGG). PLCβ1 expression is significantly higher in grade III gliomas than that in grade IV gliomas from GDS1815 (n = 24 vs. 76), GDS1962 (n = 19 vs. 81), and GDS1975 (n = 26 vs. 59). In GDS1815, PLCβ1 expression correlates with several known proneural (PN) signature genes; its expression from PN subtype (n = 15) is significantly higher than that from mesenchymal (Mes) subtype (n = 33) HGG. In GDS1962, PLCβ1 expression is the highest in nontumor brain tissue (n = 23) and is significantly higher than its expression in grade II gliomas [astrocytomas (n = 7) and oligodendrogliomas (n = 37)]. A Kaplan-Meier survival curve from a REMBRANDT cohort demonstrates that glioma patients with intermediate PLCβ1 expression (n = 103) survived significantly longer than PLCβ1 downregulated (2X) groups (n = 226). From TCGA data, PLCβ1 RNA-Seq signal inversely correlates with the pathological grades, and PLCβ1 expression in PN (n = 8) is of significantly higher levels than that in Mes (n = 8) subtypes of glioblastoma. The top 50 % of PLCβ1 expression subgroup (n = 294) of gliomas (grades II to IV merged) survived significantly longer than the low 50 percentile of the PLCβ1 expression subgroup (n = 293). p values are less than 0.05 for all these analyses. We conclude that PLCβ1 is a candidate signature gene for PN subtype HGG, and its expression inversely correlates with glioma pathological grade and is a potential prognostic factor.
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Affiliation(s)
- Guangrong Lu
- The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston (UTHealth) Medical School, 6400 Fannin Street, Suite 2800, Houston, TX, 77030, USA
| | - Jeffrey T Chang
- The Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston (UTHealth) Medical School, Houston, TX, 77030, USA
| | - Zheyu Liu
- Division of Biostatistics, UTHealth School of Public Health, Houston, TX, 77030, USA
| | - Yong Chen
- Division of Biostatistics, UTHealth School of Public Health, Houston, TX, 77030, USA
- Department of Biostatistics and Epidemiology, Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Min Li
- The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston (UTHealth) Medical School, 6400 Fannin Street, Suite 2800, Houston, TX, 77030, USA
- The Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston (UTHealth) Medical School, Houston, TX, 77030, USA
- Department of Medicine and Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Jay-Jiguang Zhu
- The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston (UTHealth) Medical School, 6400 Fannin Street, Suite 2800, Houston, TX, 77030, USA.
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4
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Bavelloni A, Dmitrienko GI, Goodfellow VJ, Ghavami A, Piazzi M, Blalock W, Chiarini F, Cocco L, Faenza I. PLCβ1a and PLCβ1b selective regulation and cyclin D3 modulation reduced by kinamycin F during k562 cell differentiation. J Cell Physiol 2015; 230:587-94. [PMID: 25160985 DOI: 10.1002/jcp.24776] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 08/22/2014] [Indexed: 11/08/2022]
Abstract
Here we report that both PLCβ1a and PLCβ1b are relevant regulators of erythropoiesis in that kinamycin F, a potent inducer of γ-globin production in K562 cells, caused a selectively reduction of both PLCβ1 isozymes even though the results point out that the effect of the drug is mainly directed toward the expression of the PLCβ1a isoform. We have identified a different role for the two isozymes as regulators of K562 differentiation process induced by kinamycin F. The overexpression of PLCβ1b induced an increase in γ-globin expression even in the absence of kinamycin F. Moreover during K562 differentiation, cyclin D3 level is regulated by PLCβ1 signaling pathway. Namely the amplification of the expression of the PLCβ1a, but not of PLCβ1b, is able to maintain high levels of expression of cyclin D3 even after treatment with kinamycin F. This could be due to their different distribution in the cell compartments since the amount of PLCβ1b is mainly present in the nucleus in respect to PLCβ1a. Our data indicate that the amplification of PLCβ1a expression, following treatment with kinamycin F, confers a real advantage to K562 cells viability and protects cells themselves from apoptosis.
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Affiliation(s)
- Alberto Bavelloni
- SC Laboratory of Musculoskeletal Cell Biology, Rizzoli Orthopedic Institute, Bologna, Italy; Laboratory RAMSES, Rizzoli Orthopedic Institute, Bologna, Italy
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5
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Brenner AK, Reikvam H, Lavecchia A, Bruserud Ø. Therapeutic targeting the cell division cycle 25 (CDC25) phosphatases in human acute myeloid leukemia--the possibility to target several kinases through inhibition of the various CDC25 isoforms. Molecules 2014; 19:18414-47. [PMID: 25397735 PMCID: PMC6270710 DOI: 10.3390/molecules191118414] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/28/2014] [Accepted: 11/02/2014] [Indexed: 01/26/2023] Open
Abstract
The cell division cycle 25 (CDC25) phosphatases include CDC25A, CDC25B and CDC25C. These three molecules are important regulators of several steps in the cell cycle, including the activation of various cyclin-dependent kinases (CDKs). CDC25s seem to have a role in the development of several human malignancies, including acute myeloid leukemia (AML); and CDC25 inhibition is therefore considered as a possible anticancer strategy. Firstly, upregulation of CDC25A can enhance cell proliferation and the expression seems to be controlled through PI3K-Akt-mTOR signaling, a pathway possibly mediating chemoresistance in human AML. Loss of CDC25A is also important for the cell cycle arrest caused by differentiation induction of malignant hematopoietic cells. Secondly, high CDC25B expression is associated with resistance against the antiproliferative effect of PI3K-Akt-mTOR inhibitors in primary human AML cells, and inhibition of this isoform seems to reduce AML cell line proliferation through effects on NFκB and p300. Finally, CDC25C seems important for the phenotype of AML cells at least for a subset of patients. Many of the identified CDC25 inhibitors show cross-reactivity among the three CDC25 isoforms. Thus, by using such cross-reactive inhibitors it may become possible to inhibit several molecular events in the regulation of cell cycle progression and even cytoplasmic signaling, including activation of several CDKs, through the use of a single drug. Such combined strategies will probably be an advantage in human cancer treatment.
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Affiliation(s)
- Annette K Brenner
- Section for Hematology, Institute of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Bergen, 5021, Norway
| | - Håkon Reikvam
- Section for Hematology, Institute of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Bergen, 5021, Norway
| | - Antonio Lavecchia
- "Drug Discovery" Laboratory, Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy
| | - Øystein Bruserud
- Section for Hematology, Institute of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Bergen, 5021, Norway.
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6
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Follo MY, Faenza I, Piazzi M, Blalock WL, Manzoli L, McCubrey JA, Cocco L. Nuclear PI-PLCβ1: an appraisal on targets and pathology. Adv Biol Regul 2013; 54:2-11. [PMID: 24296032 DOI: 10.1016/j.jbior.2013.11.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 11/16/2022]
Abstract
Lipid signalling molecules are essential components of the processes that allow one extracellular signal to be transferred inside the nucleus, where specific lipid second messengers elicit reactions capable of regulating gene transcription, DNA replication or repair and DNA cleavage, eventually resulting in cell growth, differentiation, apoptosis or many other cell functions. Nuclear inositides are independently regulated, suggesting that the nucleus constitutes a functionally distinct compartment of inositol lipids metabolism. Indeed, nuclear inositol lipids themselves can modulate nuclear processes, such as transcription and pre-mRNA splicing, growth, proliferation, cell cycle regulation and differentiation. Nuclear PI-PLCβ1 is a key molecule for nuclear inositide signalling, where it plays a role in cell cycle progression, proliferation and differentiation. Here we review the targets and possible involvement of nuclear PI-PLCβ1 in human physiology and pathology.
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Affiliation(s)
- Matilde Y Follo
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
| | - Irene Faenza
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Manuela Piazzi
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - William L Blalock
- CNR - Consiglio Nazionale delle Ricerche, Istituto di Genetica Molecolare and SC Laboratorio di Biologia Cellulare Muscoloscheletrica, IOR, Bologna, Italy
| | - Lucia Manzoli
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
| | - Lucio Cocco
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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7
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Faenza I, Fiume R, Piazzi M, Colantoni A, Cocco L. Nuclear inositide specific phospholipase C signalling - interactions and activity. FEBS J 2013; 280:6311-21. [PMID: 23890371 DOI: 10.1111/febs.12450] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 06/26/2013] [Accepted: 07/18/2013] [Indexed: 01/07/2023]
Abstract
Evidence accumulated over the past 20 years has highlighted the presence of an autonomous nuclear inositol lipid metabolism, and suggests that lipid signalling molecules are important components of signalling pathways operating within the nucleus. Nuclear polyphosphoinositide (PI) signalling relies on the synthesis and metabolism of phosphatidylinositol 4,5-bisphosphate, which can modulate the activity of effector proteins and is a substrate of signalling enzymes. The regulation of the nuclear PI pool is totally independent from the plasma membrane counterpart, suggesting that the nucleus constitutes a functionally distinct compartment of inositol lipids metabolism. Among the nuclear enzymes involved in PI metabolism, inositide specific phospholipase C (PI-PLC) has been one of the most extensively studied. Several isoforms of PI-PLCs have been identified in the nucleus, namely PI-PLC-β1, γ1, δ1 and ζ; however, the β1 isozyme is the best characterized. In the present review, we focus on the signal transduction-related metabolism of nuclear PI-PLC and review the most convincing evidence for PI-PLC expression and activity being involved in differentiation and proliferation programmes in several cell systems. Moreover, nuclear PI-PLC is an intermediate effector and interactor for nuclear inositide signalling. The inositide cycle exists and shows a biological role inside the nucleus. It is an autonomous lipid-dependent signalling system, independently regulated with respect to the one at the plasma membrane counterpart, and is involved in cell cycle progression and differentiation.
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Affiliation(s)
- Irene Faenza
- Cell Signaling Laboratory, Department of Biomedical Science (DIBINEM), University of Bologna, Italy
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8
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Wang X, Barrett M, Sondek J, Harden TK, Zhang Q. Fluorescent phosphatidylinositol 4,5-bisphosphate derivatives with modified 6-hydroxy group as novel substrates for phospholipase C. Biochemistry 2012; 51:5300-6. [PMID: 22703043 DOI: 10.1021/bi300637h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The capacity to monitor spatiotemporal activity of phospholipase C (PLC) isozymes with a PLC-selective sensor would dramatically enhance understanding of the physiological function and disease relevance of these signaling proteins. Previous structural and biochemical studies defined critical roles for several of the functional groups of the endogenous substrate of PLC isozymes, phosphatidylinositol 4,5-bisphosphate (PIP(2)), indicating that these sites cannot be readily modified without compromising interactions with the lipase active site. However, the role of the 6-hydroxy group of PIP(2) for interaction and hydrolysis by PLC has not been explored, possibly due to challenges in synthesizing 6-hydroxy derivatives. Here, we describe an efficient route for the synthesis of novel, fluorescent PIP(2) derivatives modified at the 6-hydroxy group. Two of these derivatives were used in assays of PLC activity in which the fluorescent PIP(2) substrates were separated from their diacylglycerol products and reaction rates quantified by fluorescence. Both PIP(2) analogues effectively function as substrates of PLC-δ1, and the K(M) and V(max) values obtained with one of these are similar to those observed with native PIP(2) substrate. These results indicate that the 6-hydroxy group can be modified to develop functional substrates for PLC isozymes, thereby serving as the foundation for further development of PLC-selective sensors.
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Affiliation(s)
- Xiaoyang Wang
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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9
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Huang W, Hicks SN, Sondek J, Zhang Q. A fluorogenic, small molecule reporter for mammalian phospholipase C isozymes. ACS Chem Biol 2011; 6:223-8. [PMID: 21158426 DOI: 10.1021/cb100308n] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Phospholipase C isozymes (PLCs) catalyze the conversion of the membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)) into two second messengers, inositol 1,4,5-trisphosphate and diacylglycerol. This family of enzymes are key signaling proteins that regulate the physiological responses of many extracellular stimuli such as hormones, neurotransmitters, and growth factors. Aberrant regulation of PLCs has been implicated in various diseases including cancer and Alzheimer's disease. How, when, and where PLCs are activated under different cellular contexts are still largely unknown. We have developed a fluorogenic PLC reporter, WH-15, that can be cleaved in a cascade reaction to generate fluorescent 6-aminoquinoline. When applied in enzymatic assays with either pure PLCs or cell lysates, this reporter displays more than a 20-fold fluorescence enhancement in response to PLC activity. Under assay conditions, WH-15 has comparable K(m) and V(max) with the endogenous PIP(2). This novel reporter will likely find broad applications that vary from imaging PLC activity in live cells to high-throughput screening of PLC inhibitors.
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Affiliation(s)
- Weigang Huang
- Division of Medicinal Chemistry and Natural Products and ‡Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Stephanie N. Hicks
- Division of Medicinal Chemistry and Natural Products and ‡Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - John Sondek
- Division of Medicinal Chemistry and Natural Products and ‡Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Qisheng Zhang
- Division of Medicinal Chemistry and Natural Products and ‡Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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10
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Reduction of phosphoinositide-phospholipase C beta1 methylation predicts the responsiveness to azacitidine in high-risk MDS. Proc Natl Acad Sci U S A 2009; 106:16811-6. [PMID: 19805378 DOI: 10.1073/pnas.0907109106] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lipid signaling pathways are involved in cell growth, differentiation, and apoptosis, and could have a role in the progression of myelodysplastic syndromes (MDS) into acute myeloid leukemia (AML). Indeed, recent studies showed that phosphoinositide-phospholipase (PI-PL)Cbeta1 mono-allelic deletion correlates with a higher risk of AML evolution. Also, a single patient treated with azacitidine, a DNA methyltransferase inhibitor currently used in MDS, displayed a direct correlation between PI-PLCbeta1 gene expression and drug responsiveness. Consequently, we hypothesized that PI-PLCbeta1 could be a target for demethylating therapy. First, we analyzed the structure of PI-PLCbeta1 gene promoter, then quantified the degree of PI-PLCbeta1 promoter methylation and gene expression in MDS patients at baseline and during azacitidine administration. Indeed, PI-PLCbeta1 mRNA increased in responder patients, along with a reduction of PI-PLCbeta1 promoter methylation. Also, the molecular response correlated to and anticipated the clinical outcome, thus suggesting that PI-PLCbeta1 gene reactivation could predict azacitidine responsiveness. Our results demonstrate not only that PI-PLCbeta1 promoter is hypermethylated in high-risk MDS patients, but also that the amount of PI-PLCbeta1 mRNA could predict the clinical response to azacitidine, therefore indicating a promising new therapeutic approach.
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11
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Follo MY, Mongiorgi S, Bosi C, Cappellini A, Finelli C, Chiarini F, Papa V, Libra M, Martinelli G, Cocco L, Martelli AM. The Akt/Mammalian Target of Rapamycin Signal Transduction Pathway Is Activated in High-Risk Myelodysplastic Syndromes and Influences Cell Survival and Proliferation. Cancer Res 2007; 67:4287-94. [PMID: 17483341 DOI: 10.1158/0008-5472.can-06-4409] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Akt/mammalian target of rapamycin (mTOR) signaling pathway is important for both cell growth and survival. In particular, an impaired regulation of the Akt/mTOR axis has been strongly implicated in mechanisms related to neoplastic transformation, through enhancement of cell proliferation and survival. Myelodysplastic syndromes (MDS) are a group of heterogeneous hematopoietic stem cell disorders characterized by ineffective hematopoiesis and by a high risk of evolution into acute myelogenous leukemia (AML). The pathogenesis of the MDS evolution into AML is still unclear, although some recent studies indicate that aberrant activation of survival signaling pathways could be involved. In this investigation, done by means of immunofluorescent staining, we report an activation of the Akt/mTOR pathway in high-risk MDS patients. Interestingly, not only mTOR was activated but also its downstream targets, 4E-binding protein 1 and p70 ribosomal S6 kinase. Treatment with the selective mTOR inhibitor, rapamycin, significantly increased apoptotic cell death of CD33(+) (but not CD33(-)) cells from high-risk MDS patients. Rapamycin was ineffective in cells from healthy donors or low-risk MDS. Moreover, incubation of high-risk MDS patient CD34(+) cells with rapamycin decreased the in vitro clonogenic capability of these cells. In contrast, the phosphoinositide 3-kinase inhibitor, LY294002, did not significantly affect the clonogenic activity of high-risk MDS cells. Taken together, our results indicate that the Akt/mTOR pathway is critical for cell survival and proliferation in high-risk MDS patients. Therefore, this signaling network could become an interesting therapeutic target for treating more advanced MDS cases.
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Affiliation(s)
- Matilde Y Follo
- Cell Signaling Laboratory, Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia and Istituto di Ematologia ed Oncologia Medica "L. e A. Seràgnoli," Università di Bologna, Bologna, Italy
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12
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Bavelloni A, Faenza I, Cioffi G, Piazzi M, Parisi D, Matic I, Maraldi NM, Cocco L. Proteomic-based analysis of nuclear signaling: PLCbeta1 affects the expression of the splicing factor SRp20 in Friend erythroleukemia cells. Proteomics 2007; 6:5725-34. [PMID: 17022104 DOI: 10.1002/pmic.200600318] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
An extensive body of evidence links inositide-specific phospholipase C (PLC) to the nucleus and the main isoform located in the nucleus is PLCbeta(1). Constitutive overexpression of nuclear PLCbeta(1) has been previously shown to inhibit Friend erythroleukemia cells differentiation and to induce cell cycle progression targeting cyclin D3. The aim of this study was to identify new proteins regulated by PLCbeta(1) overexpression, given the role exerted by its signaling in the nucleus during cell growth and differentiation. To identify novel downstream effectors of nuclear PLCbeta(1)-dependent signaling in Friend erythroleukemia cells, we performed the high-resolution 2-DE-based proteomic analysis. Using a proteomic approach we found that SRp20, a member of the highly conserved SR family of splicing regulators, was down-regulated in cells overexpressing nuclear PLCbeta(1) as compared with wild-type cells. Reduction in SRp20 was confirmed by 2-D Western blotting. Moreover, we have shown that nuclear PLCbeta(1) is bound to the SRp20 splicing factor. Indeed, by immunoprecipitation and subcellular fractioning, we have demonstrated that endogenous PLCbeta(1) and SRp20 physically interact in the nucleus. Here we show the existence of a PLCbeta(1)-specific target, the splicing factor SRp20, whose expression is specifically down-regulated by the nuclear signaling evoked by PLCbeta(1).
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MESH Headings
- Animals
- Blotting, Western
- Cell Nucleus/metabolism
- Cells, Cultured
- Down-Regulation
- Electrophoresis, Gel, Two-Dimensional
- Fluorescein-5-isothiocyanate
- Fluorescent Antibody Technique, Direct
- Fluorescent Dyes
- Gene Expression Regulation, Neoplastic
- Isoelectric Focusing
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Leukemia, Erythroblastic, Acute/metabolism
- Leukemia, Erythroblastic, Acute/pathology
- Mice
- Microscopy, Fluorescence
- Peptide Mapping
- Phospholipase C beta
- Precipitin Tests
- Proteomics/methods
- RNA-Binding Proteins/metabolism
- RNA-Binding Proteins/physiology
- Serine-Arginine Splicing Factors
- Signal Transduction
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Subcellular Fractions/metabolism
- Type C Phospholipases/genetics
- Type C Phospholipases/metabolism
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Affiliation(s)
- Alberto Bavelloni
- Laboratory of Cell Biology and Electron Microscopy, IOR, Bologna Italy
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13
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Cocco L, Follo MY, Faenza I, Bavelloni A, Billi AM, Martelli AM, Manzoli L. Nuclear inositide signaling: An appraisal of phospholipase C β1 behavior in myelodysplastic and leukemia cells. ACTA ACUST UNITED AC 2007; 47:2-9. [PMID: 17335878 DOI: 10.1016/j.advenzreg.2006.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Lucio Cocco
- Cellular Signalling Laboratory, Department of Anatomical Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy.
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14
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Miyara F, Pesty A, Migne C, Djediat C, Huang XB, Dumont-Hassan M, Debey P, Lefèvre B. Spontaneous calcium oscillations and nuclear PLC-β1 in human GV oocytes. Mol Reprod Dev 2007; 75:392-402. [PMID: 17620288 DOI: 10.1002/mrd.20749] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Our aim was to investigate if human oocytes, like mouse oocytes, exhibit spontaneous Ca(2+) oscillations and nuclear translocation of PLC-beta1 prior to germinal vesicle breakdown (GVBD), and to correlate these events with the evolution of chromatin configuration as a landmark for the meiosis resumption kinetics. Human germinal vesicle (GV) oocytes were either loaded with Fluo-3 probe to record Ca(2+) signals or fixed for subsequent fluorescent labeling of both chromatin and PLC-beta1, and immunogold labeling of PLC-beta1. Here for the first time, we show that human oocytes at the GV-stage exhibit spontaneous Ca(2+) oscillations. Interestingly, only oocytes with a large diameter and characterized by a compact chromatin surrounding the nucleolus of the GV could reveal these kind of oscillations. We also observed a translocation of PLC-beta1 from the cytoplasm towards the nucleus during in vitro maturation of human oocytes. Spontaneous calcium oscillations and nuclear translocation of PLC-beta1 may reflect some degree of oocyte maturity. The impact of our results may be very helpful to understand and resolve many enigmatic problems usually encountered during the in vitro meiotic maturation of human GV oocytes.
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Affiliation(s)
- F Miyara
- INRA, UMR 1198, INRA Domaine de Vilvert, Jouy en Josas Cedex, France
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