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Hoboth P, Sztacho M, Hozák P. Nuclear patterns of phosphatidylinositol 4,5- and 3,4-bisphosphate revealed by super-resolution microscopy differ between the consecutive stages of RNA polymerase II transcription. FEBS J 2024. [PMID: 38734927 DOI: 10.1111/febs.17136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/12/2023] [Accepted: 04/05/2024] [Indexed: 05/13/2024]
Abstract
Phosphatidylinositol phosphates are powerful signaling molecules that orchestrate signaling and direct membrane trafficking in the cytosol. Interestingly, phosphatidylinositol phosphates also localize within the membrane-less compartments of the cell nucleus, where they participate in the regulation of gene expression. Nevertheless, current models of gene expression, which include condensates of proteins and nucleic acids, do not include nuclear phosphatidylinositol phosphates. This gap is partly a result of the missing detailed analysis of the subnuclear distribution of phosphatidylinositol phosphates and their relationships with gene expression. Here, we used quantitative dual-color direct stochastic optical reconstruction microscopy to analyze the nanoscale co-patterning between RNA polymerase II transcription initiation and elongation markers with respect to phosphatidylinositol 4,5- or 3,4-bisphosphate in the nucleoplasm and nuclear speckles and compared it with randomized data and cells with inhibited transcription. We found specific co-patterning of the transcription initiation marker P-S5 with phosphatidylinositol 4,5-bisphosphate in the nucleoplasm and with phosphatidylinositol 3,4-bisphosphate at the periphery of nuclear speckles. We showed the specific accumulation of the transcription elongation marker PS-2 and of nascent RNA in the proximity of phosphatidylinositol 3,4-bisphosphate associated with nuclear speckles. Taken together, this shows that the distinct spatial associations between the consecutive stages of RNA polymerase II transcription and nuclear phosphatidylinositol phosphates exhibit specificity within the gene expression compartments. Thus, in analogy to the cellular membranes, where phospholipid composition orchestrates signaling pathways and directs membrane trafficking, we propose a model in which the phospholipid identity of gene expression compartments orchestrates RNA polymerase II transcription.
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Affiliation(s)
- Peter Hoboth
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Viničná Microscopy Core Facility, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Sztacho
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Laboratory of Cancer Cell Architecture, Institute of Biochemistry and Experimental Oncology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Pavel Hozák
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
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2
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Huang AY. Immune Responses Alter Taste Perceptions: Immunomodulatory Drugs Shape Taste Signals during Treatments. J Pharmacol Exp Ther 2019; 371:684-691. [PMID: 31611237 DOI: 10.1124/jpet.119.261297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/08/2019] [Indexed: 01/01/2023] Open
Abstract
Considering that nutrients are required in health and diseases, the detection and ingestion of food to meet the requirements is attributable to the sense of taste. Altered taste sensations lead to a decreased appetite, which is usually one of the frequent causes of malnutrition in patients with diseases. Ongoing taste research has identified a variety of drug pathways that cause changes in taste perceptions in cancer, increasing our understanding of taste disturbances attributable to aberrant mechanisms of taste sensation. The evidence discussed in this review, which addresses the implications of innate immune responses in the modulation of taste functions, focuses on the adverse effects on taste transmission from taste buds by immune modulators responsible for alterations in the perceived intensity of some taste modalities. Another factor, damage to taste progenitor cells that directly results in local effects on taste buds, must also be considered in relation to taste disturbances in patients with cancer. Recent discoveries discussed have provided new insights into the pathophysiology of taste dysfunctions associated with the specific treatments. SIGNIFICANCE STATEMENT: The paradigm that taste signals transmitted to the brain are determined only by tastant-mediated activation via taste receptors has been challenged by the immune modification of taste transmission through drugs during the processing of gustatory information in taste buds. This article reports the findings in a model system (mouse taste buds) that explain the basis for the taste dysfunctions in patients with cancer that has long been observed but never understood.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy and Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, Illinois
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3
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Huang AY, Wu SY. The effect of imiquimod on taste bud calcium transients and transmitter secretion. Br J Pharmacol 2016; 173:3121-3133. [PMID: 27464850 DOI: 10.1111/bph.13567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/07/2016] [Accepted: 07/19/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Imiquimod is an immunomodulator approved for the treatment of basal cell carcinoma and has adverse side effects, including taste disturbances. Paracrine transmission, representing cell-cell communication within taste buds, has the potential to shape the final signals that taste buds transmit to the brain. Here, we tested the underlying assumption that imiquimod modifies taste transmitter secretion in taste buds of mice. EXPERIMENTAL APPROACH Taste buds were isolated from C57BL/6J mice. The effects of imiquimod on transmitter release in taste buds were measured using calcium imaging with cellular biosensors, and examining the net effect of imiquimod on taste-evoked ATP secretion from mouse taste buds. KEY RESULTS Up to 72% of presynaptic (Type III) taste cells responded to 100 μM imiquimod with an increase in intracellular Ca2+ concentrations. These Ca2+ responses were inhibited by thapsigargin, an inhibitor of the sarco/endoplasmic reticulum Ca2+ -ATPase, and by U73122, a PLC inhibitor, suggesting that the Ca2+ mobilization elicited by imiquimod was dependent on release from internal Ca2+ stores. Moreover, combining studies of Ca2+ imaging with cellular biosensors showed that imiquimod evoked secretion of 5-HT, which then provided negative feedback onto receptor (Type II) cells to reduce taste-evoked ATP secretion. CONCLUSION AND IMPLICATIONS Our results provide evidence that there is a subset of taste cells equipped with a range of intracellular mechanisms that respond to imiquimod. The findings are also consistent with a role of imiquimod as an immune response modifier, which shapes peripheral taste responses via 5-HT signalling.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA. .,Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, IL, USA.
| | - Sandy Y Wu
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA
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4
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Hamaguchi N, Ohdaira T, Shinohara A, Iwamatsu A, Ihara S, Fukui Y. Identification of ribosomal protein S3a as a candidate for a novel PI 3-kinase target in the nucleus. Cytotechnology 2011; 40:85-92. [PMID: 19003108 DOI: 10.1023/a:1023970222898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) is an important lipid second messenger that mediates various cell responses. We have searched for the nuclear PIP(3) binding proteins using PIP(3) analogue beads. A 33 kD protein was detected in this method, which was identified as ribosomal protein S3a by the mass spectrometric analysis. The recombinant S3a protein bound specifically to PIP(3). S3a localized not only in the cytosol but also in the nucleus. Interestingly, not cytosolic but nuclear S3a bound to PIP(3), suggesting different roles of S3a in the cytosol and the nucleus.
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Affiliation(s)
- Norihisa Hamaguchi
- Laboratory of Biological Chemistry, Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
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5
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Lo Vasco VR, Fabrizi C, Panetta B, Fumagalli L, Cocco L. Expression pattern and sub-cellular distribution of phosphoinositide specific phospholipase C enzymes after treatment with U-73122 in rat astrocytoma cells. J Cell Biochem 2010; 110:1005-12. [PMID: 20564200 DOI: 10.1002/jcb.22614] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Phosphoinositide specific phospholipase C (PI-PLC) enzymes interfere with the metabolism of inositol phospholipids (PI), molecules involved in signal transduction, a complex process depending on various components. Many evidences support the hypothesis that, in the glia, isoforms of PI-PLC family display different expression and/or sub cellular distribution under non-physiological conditions such as the rat astrocytes activation during neurodegeneration, the tumoural progression of some neoplasms and the inflammatory cascade activation after lipopolysaccharide administration, even if their role remains not completely elucidated. Treatment of a cultured established glioma cell line (C6 rat astrocytoma cell line) induces a modification in the pattern of expression and of sub cellular distribution of PI-PLCs compared to untreated cells. Special attention require PI-PLC beta3 and PI-PLC gamma2 isoforms, whose expression and sub cellular localization significantly differ after U-73122 treatment. The meaning of these modifications is unclear, also because the use of this N-aminosteroid compound remains controversial, inasmuch it has further actions which might contribute to the global effect recorded on the treated cells.
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Affiliation(s)
- Vincenza Rita Lo Vasco
- Department of Otorinolaringoiatria, Audiologia and Foniatria "G. Ferreri", Policlinico Umberto I, Rome, Italy.
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6
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Grinberg S, Hasko G, Wu D, Leibovich SJ. Suppression of PLCbeta2 by endotoxin plays a role in the adenosine A(2A) receptor-mediated switch of macrophages from an inflammatory to an angiogenic phenotype. Am J Pathol 2009; 175:2439-53. [PMID: 19850892 DOI: 10.2353/ajpath.2009.090290] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Toll-like receptor (TLR) 2, 4, 7, and 9 agonists, together with adenosine A(2A) receptor (A(2A)R) agonists, switch macrophages from an inflammatory (M1) to an angiogenic (M2-like) phenotype. This switch involves induction of A(2A)Rs by TLR agonists, down-regulation of tumor necrosis factor alpha (TNFalpha) and interleukin-12, and up-regulation of vascular endothelial growth factor (VEGF) and interleukin-10 expression. We show here that the TLR4 agonist lipopolysaccharide (LPS) induces rapid and specific post-transcriptional down-regulation of phospholipase C(PLC)beta1 and beta2 expression in macrophages by de-stabilizing their mRNAs. The PLCbeta inhibitor U73122 down-regulates TNFalpha expression by macrophages, and in the presence of A(2A)R agonists, up-regulates VEGF, mimicking the synergistic action of LPS with A(2A)R agonists. Selective down-regulation of PLCbeta2, but not PLCbeta1, using small-interfering RNA resulted in increased VEGF expression in response to A(2A)R agonists, but did not suppress TNFalpha expression. Macrophages from PLCbeta2(-/-) mice also expressed increased VEGF in response to A(2A)R agonists. LPS-mediated suppression of PLCbeta1 and beta2 is MyD88-dependent. In a model of endotoxic shock, LPS (35 microg/mouse, i.p.) suppressed PLCbeta1 and beta2 expression in spleen, liver, and lung of wild-type but not MyD88(-/-) mice. These studies indicate that LPS suppresses PLCbeta1 and beta2 expression in macrophages in vitro and in several tissues in vivo. These results suggest that suppression of PLCbeta2 plays an important role in switching M1 macrophages into an M2-like state.
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Affiliation(s)
- Stan Grinberg
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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Barlow CA, Laishram RS, Anderson RA. Nuclear phosphoinositides: a signaling enigma wrapped in a compartmental conundrum. Trends Cell Biol 2009; 20:25-35. [PMID: 19846310 DOI: 10.1016/j.tcb.2009.09.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 09/27/2009] [Accepted: 09/28/2009] [Indexed: 01/09/2023]
Abstract
While the presence of phosphoinositides in the nuclei of eukaryotes and the identity of the enzymes responsible for their metabolism have been known for some time, their functions in the nucleus are only now emerging. This is illustrated by the recent identification of effectors for nuclear phosphoinositides. Like the cytosolic phosphoinositide signaling pathway, nuclear phosphatidylinositol 4,5-bisphosphate (PI4,5P(2)) is at the center of the pathway and acts both as a messenger and as a precursor for many additional messengers. Here, recent advances in the understanding of nuclear phosphoinositide signaling and its functions are reviewed with an emphasis on PI4,5P(2) and its role in gene expression. The compartmentalization of nuclear phosphoinositide phosphates (PIP(n)) remains a mystery, but emerging evidence suggests that phosphoinositides occupy several functionally distinct compartments.
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Affiliation(s)
- Christy A Barlow
- University of Wisconsin-Madison, Department of Pharmacology, 1300 University Ave. University of Wisconsin Medical School, Madison, WI 53706, USA
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Klein BM, Andrews JB, Bannan BA, Nazario-Toole AE, Jenkins TC, Christensen KD, Oprisan SA, Meyer-Bernstein EL. Phospholipase C beta 4 in mouse hepatocytes: rhythmic expression and cellular distribution. Comp Hepatol 2008; 7:8. [PMID: 18957089 PMCID: PMC2583973 DOI: 10.1186/1476-5926-7-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Accepted: 10/28/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND Circadian regulated physiological processes have been well documented in the mammalian liver. Phospholipases are important mediators of both cytoplasmic and nuclear signaling mechanisms in hepatocytes, and despite a potentially critical role for these enzymes in regulating the temporal aspect of hepatic physiology, their involvement in the circadian liver clock has not been the subject of much investigation. The phospholipase C beta4 (PLCbeta4) enzyme is of particular interest as it has been linked to circadian clock function. In general, there is no knowledge of the role of the PLCbeta4 isozyme in mammalian hepatocytes as this is the first report of its expression in the mammalian liver. RESULTS We found that in the liver of mice housed on a light:dark cycle, PLCbeta4 protein underwent a significant circadian rhythm with a peak occurring during the early night. In constant darkness, the protein rhythm was more robust and peaked around dusk. We also observed a significant oscillation in plcbeta4 gene expression in the livers of mice housed in both photoperiodic and constant dark conditions. The cellular distribution of the protein in hepatocytes varied over the course of the circadian day with PLCbeta4 primarily cytoplasmic around dusk and nuclear at dawn. CONCLUSION Our results indicate that PLCbeta4 gene and protein expression is regulated by a circadian clock in the mouse liver and is not dependent on the external photoperiod. A light-independent daily translocation of PLCbeta4 implies that it may play a key role in nuclear signaling in hepatocytes and serve as a daily temporal cue for physiological processes in the liver.
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Affiliation(s)
- Brittany M Klein
- Department of Biology and Program in Neuroscience, College of Charleston, Charleston, SC 29424, USA.
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9
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Lo Vasco VR, Fabrizi C, Artico M, Cocco L, Billi AM, Fumagalli L, Manzoli FA. Expression of phosphoinositide-specific phospholipase C isoenzymes in cultured astrocytes. J Cell Biochem 2007; 100:952-9. [PMID: 17063484 DOI: 10.1002/jcb.21048] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Signal transduction from plasma membrane to cell nucleus is a complex process depending on various components including lipid signaling molecules, in particular phosphoinositides and their related enzymes, which act at cell periphery and/or plasma membrane as well as at nuclear level. As far as the nervous system may concern the inositol lipid cycle has been hypothesized to be involved in numerous neural as well as glial functions. In this context, however, a precise panel of glial PLC isoforms has not been determined yet. In the present experiments we investigated astrocytic PLC isoforms in astrocytes obtained from foetal primary cultures of rat brain and from an established cultured (C6) rat astrocytoma cell line, two well known cell models for experimental studies on glia. Identification of PLC isoforms was achieved by using a combination of RT-PCR and immunocytochemistry experiments. While in both cell models the most represented PI-PLC isoforms were beta4, gamma1, delta4, and epsilon, isoforms PI-PLC beta2 and delta3 were not detected. Moreover, in primary astrocyte cultures PI-PLC delta3 resulted well expressed in C6 cells but was absent in astrocytes. Immunocytochemistry performed with antibodies against specific PLC isoforms substantially confirmed this pattern of expression both in astrocytes and C6 glioma cells. In particular while some isoenzymes (namely isoforms beta3 and beta4) resulted mainly nuclear, others (isoforms delta4 and epsilon) were preferentially localized at cytoplasmic and plasma membrane level.
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Affiliation(s)
- Vincenza Rita Lo Vasco
- Department of Fisiologia e Farmacologia V Erspamer, Respiratorie e Morfologiche, University of Rome La Sapienza, Rome, Italy
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10
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Cocco L, Faenza I, Fiume R, Maria Billi A, Gilmour RS, Manzoli FA. Phosphoinositide-specific phospholipase C (PI-PLC) β1 and nuclear lipid-dependent signaling. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:509-21. [PMID: 16624616 DOI: 10.1016/j.bbalip.2006.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 03/02/2006] [Accepted: 03/03/2006] [Indexed: 10/24/2022]
Abstract
Over the last years, evidence has suggested that phosphoinositides, which are involved in the regulation of a large variety of cellular processes both in the cytoplasm and in the plasma membrane, are present also within the nucleus. A number of advances has resulted in the discovery that phosphoinositide-specific phospholipase C signalling in the nucleus is involved in cell growth and differentiation. Remarkably, the nuclear inositide metabolism is regulated independently from that present elsewhere in the cell. Even though nuclear inositol lipids hydrolysis generates second messengers such as diacylglycerol and inositol 1,4,5-trisphosphate, it is becoming increasingly clear that in the nucleus polyphosphoinositides may act by themselves to influence pre-mRNA splicing and chromatin structure. Among phosphoinositide-specific phospholipase C, the beta(1) isoform appears to be one of the key players of the nuclear lipid signaling. This review aims at highlighting the most significant and up-dated findings about phosphoinositide-specific phospholipase C beta(1) in the nucleus.
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Affiliation(s)
- Lucio Cocco
- Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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11
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Abstract
A large number of observations have hinted at the fact that location impinges on function of some of the main players of nuclear inositol lipid cycle. PLC beta1 is a well-known example, given that it has been shown that only the enzyme located in the nucleus targets the cyclin D3/cdk4 complex, playing, in turn, a key role in the control of normal progression through the G1 phase of the cell cycle. The PLC beta1 gene, which is constituted of 36 small exons and large introns, maps on the short arm of human chromosome 20 (20pl2, nearby markers D20S917 and D20S177) with the specific probe (PAC clone HS881E24) spanning from exon 19 to 32 of the gene itself. The chromosome band 20pl2 has been shown to be rearranged in human diseases such as solid tumors without a more accurate definition of the alteration, maybe because of the absence of candidate genes or specific probes. Moreover, non-specific alterations in chromosome 20 have been found in patients affected by MDS and acute myeloid leukemia AML. MDS is an adult hematological disease that evolves into AML in about 30% of the cases. The availability of a highly specific probe gave an opportunity to perform in patients affected with MDS/AML, associated with normal karyotype, painting and FISH analysis aimed to check the PLC beta1 gene, given that this signaling molecule is a key player in the control of some checkpoints of the normal progression through the cell cycle. FISH analysis disclosed in a small group of MDS/AML patients with normal karyotype the monoallelic deletion of the PLC beta1 gene. In contrast, PLC beta4, another gene coding for a signaling molecule, located on 20pl2.3 at a distance as far as less than 1 Mb from PLC beta1, is unaffected in MDS patients with the deletion of PLC beta1 gene, hinting at an interstitial deletion. The MDS patients, bearing the deletion, rapidly evolved to AML, whilst the normal karyotype MDS patients, showing non-deletion of PLC beta1 gene, are still alive at least 24 months after the diagnosis. The immunocytochemical analysis using an anti PLC beta1 monoclonal antibody showed that all the AML/MDS patients who were normal at FISH analysis also had normal staining of the nucleus, which is a preferential site for PLC beta1. In contrast, the monoallelic deletion gave rise to a dramatic decrease of the nuclear staining suggesting a decreased expression of the nuclear PLC beta1. The reported data strengthen the contention of a key role played by PLC beta1 in the nucleus, suggest a possible involvement of PLC beta1 in the progression of MDS to AML and pave the way for a larger investigation aimed at identifying a possible high risk group among MDS patients with a normal karyotype.
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Affiliation(s)
- Lucio Cocco
- Cellular Signaling Laboratory, Department of Anatomical Sciences, University of Bologna, Via Irnerio 48, Bologna 40126, Italy.
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12
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Lo Vasco VR, Calabrese G, Manzoli L, Palka G, Spadano A, Morizio E, Guanciali-Franchi P, Fantasia D, Cocco L. Inositide-specific phospholipase c β1 gene deletion in the progression of myelodysplastic syndrome to acute myeloid leukemia. Leukemia 2004; 18:1122-6. [PMID: 15085153 DOI: 10.1038/sj.leu.2403368] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Myelodysplastic syndrome (MDS) is an adult hematological disease that evolves into acute myeloid leukemia (AML) in about 30% of the cases. The availability of a highly specific probe moved us to perform in patients affected with MDS/AML, associated with normal karyotype, painting and fluorescence in situ hybridization (FISH) analysis aimed to check the inositide-specific phospholipase C (PI-PLC) beta1 gene, a player in the control of some checkpoints of the cell cycle. Here we present a preliminary observation in which FISH analysis disclosed in a small group of MDS/AML patients with normal karyotype the monoallelic deletion of the PI-PLCbeta1 gene. On the contrary, PI-PLC beta4, another gene coding for a signaling molecule, located on 20p12.3 at a distance as far as less than 1Mb from PI-PLCbeta1, is unaffected in MDS patients with the deletion of PI-PLC beta1 gene, hinting at an interstitial deletion. The MDS patients, bearing the deletion, rapidly evolved to AML. The data suggest the possible involvement of PI-PLCbeta1 in the progression of the disease and pave the way for a larger investigation aimed at identifying a possible high-risk group among MDS patients with a normal karyotype.
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Affiliation(s)
- V R Lo Vasco
- Cellular Signalling Laboratory, Department of Anatomical Sciences, University of Bologna, Bologna, Italy
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13
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Abstract
Strong evidence has been accumulating over the last 15 years suggesting that phosphoinositides, which are involved in the regulation of a large variety of cellular processes in the cytoplasm and in the plasma membrane, are present within the nucleus. Several advances have resulted in the discovery that nuclear phosphoinositides are involved in cell growth and differentiation. Remarkably, the nuclear inositide metabolism is regulated independently from that present elsewhere in the cell. Although nuclear inositol lipids generate second messengers such as diacylglycerol and inositol 1,4,5-trisphosphate, it is becoming increasingly clear that in the nucleus polyphosphoinositides may act by themselves to influence pre-mRNA splicing and chromatin structure. This review aims at highlighting the most significant and updated findings about inositol lipid metabolism in the nucleus.
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Affiliation(s)
- Alberto M Martelli
- Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, via Irnerio 48, 40126, Bologna, Italy
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14
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Affiliation(s)
- Lucio Cocco
- Cellular Signaling Laboratory, Department of Anatomical Sciences, University of Bologna, via Irnerio 48, Bologna 40126, Italy.
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15
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Tabellini G, Bortul R, Santi S, Riccio M, Baldini G, Cappellini A, Billi AM, Berezney R, Ruggeri A, Cocco L, Martelli AM. Diacylglycerol kinase-theta is localized in the speckle domains of the nucleus. Exp Cell Res 2003; 287:143-54. [PMID: 12799190 DOI: 10.1016/s0014-4827(03)00115-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It is well established that the nucleus is endowed with enzymes that are involved in lipid-dependent signal transduction pathways. Diacylglycerol (DAG) is a fundamental lipid second messenger that is produced in the nucleus. Previous reports have shown that the nucleus contains diacylglycerol kinases (DGKs), i.e., the enzymes that, by converting DAG into phosphatidic acid (PA), terminate DAG-dependent events. Here, we show, by immunofluorescence staining and confocal analysis, that DGK-theta localizes mainly to the nucleus of various cell lines, such as MDA-MB-453, MCF-7, PC12, and HeLa. Nuclear DGK-theta co-localizes with phosphatidylinositol 4,5-bisphosphate (PIP(2)) in domains that correspond to nuclear speckles, as revealed by the use of an antibody to the splicing factor SC-35, a well-established marker for these structures. The spatial distribution of nuclear DGK-theta was dynamic in that it was affected by inhibition of mRNA transcription with alpha-amanitin. Immuno-electron microscopy analysis demonstrated that DGK-theta, PIP(2), and phosphoinositide-specific phospholipase Cbeta1 (PLCbeta1) associated with electron-dense particles within the nucleus that correspond to interchromatin granule clusters. Cell fractionation experiments performed in MDA-MB-453, HeLa, and PC12 cells showed a preferential association of DGK-theta with the nucleus. Western blots demonstrated that DGK-theta was enriched in the nuclear matrix fraction prepared from MDA-MB-453 cells. Immunoprecipitation experiments with an antibody to PLCbeta1 revealed in MDA-MB-453 cells an association between this enzyme and both DGK-theta and phosphatidylinositol phosphate kinase Ialpha (PIPKIalpha). Our findings strengthen the contention that speckles represent a crucial site for the nuclear-based inositol lipid cycle. We may speculate that nuclear speckle-located DGK-theta, on cell stimulation with an agonist, converts to PA the DAG derived from PLCbeta1-dependent PIP(2) hydrolysis.
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Affiliation(s)
- Giovanna Tabellini
- Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell' Apparato Locomotore, Sezione di Anatomia Umana, Cell Signalling Laboratory, Università di Bologna, 40126, Bologna, Italy
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Lambusta D, Nicolosi G, Patti A, Sanfilippo C. Application of lipase catalysis in organic solvents for selective protection–deprotection of bioactive compounds. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1381-1177(03)00042-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Abstract
It is becoming increasingly evident that stimulation of nuclear lipid metabolism plays a central role in many signal transduction pathways that ultimately result in various cell responses including proliferation and differentiation. Nuclear lipid metabolism seems to be at least as complex as that existing at the plasma membrane. However, a distinctive feature of nuclear lipid biochemical pathways is their operational independence from their cell periphery counterparts. Although initially it was thought that nuclear lipids would serve as a source for second messengers, recent evidence points to the likelihood that lipids present in the nucleus also fulfil other roles. The aim of this review is to highlight the most intriguing advances made in the field over the last year, such as the production of new probes for the in situ mapping of nuclear phosphoinositides, the identification of two sources for nuclear diacylglycerol production, the emerging details about the peculiar regulation of nuclear phosphoinositide synthesizing enzymes, and the distinct possibility that nuclear lipids are involved in processes such as chromatin organization and pre-mRNA splicing.
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Affiliation(s)
- Alberto M Martelli
- Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia, Cell Signaling Laboratory, Università di Bologna, Via Irnerio 48, Italy.
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Cocco L, Martelli AM, Vitale M, Falconi M, Barnabei O, Stewart Gilmour R, Manzoli FA. Inositides in the nucleus: regulation of nuclear PI-PLCbeta1. Adv Enzyme Regul 2002; 42:181-93. [PMID: 12123715 DOI: 10.1016/s0065-2571(01)00030-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Lucio Cocco
- Department of Anatomical Sciences, Cellular Signaling Laboratory, University of Bologna, Italy.
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Abstract
The existence and function of actin in the nucleus has been hotly debated for forty years. Recently, beta-actin was found to be a component of mammalian SWI/SNF-like BAF chromatin remodeling complexes and still more recently other SWI/SNF-related chromatin remodeling complexes in yeast, flies, and man. Although the function of actin in these chromatin remodeling complexes is only starting to be explored, the fact that actin is one of the most regulated proteins in the cell suggests that control of nuclear actin may be a critical regulatory point in the control of chromatin remodeling. Actin rapidly shuttles between the nucleus and the cytoplasm offering additional sites and modes of regulation. In addition, actin-related proteins (Arps) are also components of these chromatin remodeling complexes and have been implicated in transcriptional control in yeast. The observation that the BAF chromatin remodeling complex in which actin was originally identified, is also a human tumor suppressor complex necessary for the actions of the retinoblastoma protein indicates that the study of nuclear actin is likely to contribute to understanding cell growth control.
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Affiliation(s)
- Ivan A Olave
- Department of Developmental Biology and Department of Pathology, Howard Hughes Medical Institute at Stanford University, Stanford, California 94305, USA.
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Peruzzi D, Aluigi M, Manzoli L, Billi AM, Di Giorgio FP, Morleo M, Martelli AM, Cocco L. Molecular characterization of the human PLC beta1 gene. Biochim Biophys Acta 2002; 1584:46-54. [PMID: 12213492 DOI: 10.1016/s1388-1981(02)00269-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inositide-specific phospholipase C (PLC) signaling constitutes a central intermediate in a number of cellular functions among which the control of cell growth raises a particular interest. Indeed, we have previously shown that nuclear phospholipase C beta1 (PLC beta1) is central for the regulation of mitogen-induced cell growth. We have also assigned by fluorescence in situ hybridization (FISH) analysis the PLC beta1 to human chromosome 20p12. In this study, we have carried out a detailed analysis of the human gene, showing the existence of alternative splicing, which gives rise, besides the two forms (1a and 1b) already shown in rodents, to a new 600 bp smaller form coding for a 110 kDa protein. We have also identified a new exon at the 5', showing no homology with the rodent sequence. Here we provide the complete determination of the exon/intron structure of the gene spanning 250 kb of DNA. We found that the exons are quite small, ranging from 49 to 222 bp, while the introns vary between 108 bp and 34,400 bp. The availability of the understanding of the genome organization of this inositide-specific PLC, which represents a key step of the cell cycle related signaling, could actually pave the way for further genetic analysis of p12 region of human chromosome 20 in diseases involving alterations of the control of cell growth such as malignancies.
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Affiliation(s)
- Daniela Peruzzi
- Department of Anatomical Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio, 48, I-40126 Bologna, Italy
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Abstract
Phosphoinositides act as precursors of second messengers and membrane ligands for protein modules. Specific lipid kinases and phosphatases are located and differentially regulated in cell organelles, generating a non-uniform distribution of phosphoinositides. Although it is not clear whether and how the phosphoinositide pools are integrated, it is certain that they locally control fundamental processes, including membrane trafficking. This applies to the Golgi complex, where a direct, central role of the phosphatidylinositol 4,5-bisphosphate precursor phosphatidylinositol 4-phosphate has recently been reported.
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Affiliation(s)
- Maria De Matteis
- Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, 66030, Santa Maria Imbaro, Chieti, Italy.
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