75 results on '"Talora C"'
Search Results
52. The loss of ATP2C1 impairs the DNA damage response and induces altered skin homeostasis: Consequences for epidermal biology in Hailey-Hailey disease.
- Author
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Cialfi S, Le Pera L, De Blasio C, Mariano G, Palermo R, Zonfrilli A, Uccelletti D, Palleschi C, Biolcati G, Barbieri L, Screpanti I, and Talora C
- Subjects
- Ataxia Telangiectasia Mutated Proteins metabolism, Cell Differentiation, Epidermis pathology, Gene Expression, Humans, Keratinocytes cytology, Keratinocytes metabolism, Oxidative Stress, Pemphigus, Benign Familial genetics, Calcium-Transporting ATPases genetics, DNA Damage, Epidermis metabolism, Homeostasis, Pemphigus, Benign Familial pathology, Receptor, Notch1 metabolism
- Abstract
Mutation of the Golgi Ca(2+)-ATPase ATP2C1 is associated with deregulated calcium homeostasis and altered skin function. ATP2C1 mutations have been identified as having a causative role in Hailey-Hailey disease, an autosomal-dominant skin disorder. Here, we identified ATP2C1 as a crucial regulator of epidermal homeostasis through the regulation of oxidative stress. Upon ATP2C1 inactivation, oxidative stress and Notch1 activation were increased in cultured human keratinocytes. Using RNA-seq experiments, we found that the DNA damage response (DDR) was consistently down-regulated in keratinocytes derived from the lesions of patients with Hailey-Hailey disease. Although oxidative stress activates the DDR, ATP2C1 inactivation down-regulates DDR gene expression. We showed that the DDR response was a major target of oxidative stress-induced Notch1 activation. Here, we show that this activation is functionally important because early Notch1 activation in keratinocytes induces keratinocyte differentiation and represses the DDR. These results indicate that an ATP2C1/NOTCH1 axis might be critical for keratinocyte function and cutaneous homeostasis, suggesting a plausible model for the pathological features of Hailey-Hailey disease.
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- 2016
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53. A threshold level of NFATc1 activity facilitates thymocyte differentiation and opposes notch-driven leukaemia development.
- Author
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Klein-Hessling S, Rudolf R, Muhammad K, Knobeloch KP, Maqbool MA, Cauchy P, Andrau JC, Avots A, Talora C, Ellenrieder V, Screpanti I, Serfling E, and Patra AK
- Subjects
- Animals, B-Lymphocytes cytology, B-Lymphocytes immunology, Cell Differentiation, Cell Lineage genetics, Cell Lineage immunology, Cell Survival, Gene Expression Regulation, Developmental immunology, Lymphopenia genetics, Lymphopenia pathology, Mice, Mice, Knockout, NFATC Transcription Factors genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma pathology, Promoter Regions, Genetic, Protein Isoforms genetics, Protein Isoforms immunology, Receptor, Notch3 genetics, Receptors, Antigen, T-Cell genetics, Receptors, Antigen, T-Cell immunology, Signal Transduction, T-Lymphocytes cytology, Thymocytes cytology, Thymus Gland cytology, Thymus Gland immunology, Lymphopenia immunology, NFATC Transcription Factors immunology, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma immunology, Receptor, Notch3 immunology, T-Lymphocytes immunology, Thymocytes immunology
- Abstract
NFATc1 plays a critical role in double-negative thymocyte survival and differentiation. However, the signals that regulate Nfatc1 expression are incompletely characterized. Here we show a developmental stage-specific differential expression pattern of Nfatc1 driven by the distal (P1) or proximal (P2) promoters in thymocytes. Whereas, preTCR-negative thymocytes exhibit only P2 promoter-derived Nfatc1β expression, preTCR-positive thymocytes express both Nfatc1β and P1 promoter-derived Nfatc1α transcripts. Inducing NFATc1α activity from P1 promoter in preTCR-negative thymocytes, in addition to the NFATc1β from P2 promoter impairs thymocyte development resulting in severe T-cell lymphopenia. In addition, we show that NFATc1 activity suppresses the B-lineage potential of immature thymocytes, and consolidates their differentiation to T cells. Further, in the pTCR-positive DN3 cells, a threshold level of NFATc1 activity is vital in facilitating T-cell differentiation and to prevent Notch3-induced T-acute lymphoblastic leukaemia. Altogether, our results show NFATc1 activity is crucial in determining the T-cell fate of thymocytes.
- Published
- 2016
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54. Notch3/Jagged1 circuitry reinforces notch signaling and sustains T-ALL.
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Pelullo M, Quaranta R, Talora C, Checquolo S, Cialfi S, Felli MP, te Kronnie G, Borga C, Besharat ZM, Palermo R, Di Marcotullio L, Capobianco AJ, Gulino A, Screpanti I, and Bellavia D
- Subjects
- Animals, Apoptosis, Disease Models, Animal, Fluorescent Antibody Technique, Indirect, Immunoblotting, Jagged-1 Protein, Mice, Mice, Transgenic, Plasmids, Real-Time Polymerase Chain Reaction, Receptor, Notch3, Receptors, Notch physiology, Reverse Transcriptase Polymerase Chain Reaction, Serrate-Jagged Proteins, Transcription, Genetic, Transfection, Calcium-Binding Proteins genetics, Gene Expression Regulation, Neoplastic physiology, Intercellular Signaling Peptides and Proteins genetics, Membrane Proteins genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma pathology, Receptors, Notch genetics, Signal Transduction physiology
- Abstract
Deregulated Notch signaling has been extensively linked to T-cell acute lymphoblastic leukemia (T-ALL). Here, we show a direct relationship between Notch3 receptor and Jagged1 ligand in human cell lines and in a mouse model of T-ALL. We provide evidence that Notch-specific ligand Jagged1 is a new Notch3 signaling target gene. This essential event justifies an aberrant Notch3/Jagged1 cis-expression inside the same cell. Moreover, we demonstrate in Notch3-IC-overexpressing T lymphoma cells that Jagged1 undergoes a raft-associated constitutive processing. The proteolytic cleavage allows the Jagged1 intracellular domain to empower Notch signaling activity and to increase the transcriptional activation of Jagged1 itself (autocrine effect). On the other hand, the release of the soluble Jagged1 extracellular domain has a positive impact on activating Notch signaling in adjacent cells (paracrine effect), finally giving rise to a Notch3/Jagged1 auto-sustaining loop that supports the survival, proliferation, and invasion of lymphoma cells and contributes to the development and progression of Notch-dependent T-ALL. These observations are also supported by a study conducted on a cohort of patients in which Jagged1 expression is associated to adverse prognosis., (Copyright © 2014 Neoplasia Press, Inc. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
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55. The epigenetic factor BORIS/CTCFL regulates the NOTCH3 gene expression in cancer cells.
- Author
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Zampieri M, Ciccarone F, Palermo R, Cialfi S, Passananti C, Chiaretti S, Nocchia D, Talora C, Screpanti I, and Caiafa P
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- Cells, Cultured, DNA Methylation, Humans, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics, Promoter Regions, Genetic, Receptor, Notch3, DNA-Binding Proteins physiology, Epigenesis, Genetic, Gene Expression Regulation, Neoplastic, Receptors, Notch genetics
- Abstract
Aberrant upregulation of NOTCH3 gene plays a critical role in cancer pathogenesis. However, the underlying mechanisms are still unknown. We tested here the hypothesis that aberrant epigenetic modifications in the NOTCH3 promoter region might account for its upregulation in cancer cells. We compared DNA and histone methylation status of NOTCH3 promoter region in human normal blood cells and T cell acute lymphoblastic leukemia (T-ALL) cell lines, differentially expressing NOTCH3. We found that histone methylation, rather than DNA hypomethylation, contributes towards establishing an active chromatin status of NOTCH3 promoter in NOTCH3 overexpressing cancer cells. We discovered that the chromatin regulator protein BORIS/CTCFL plays an important role in regulating NOTCH3 gene expression. We observed that BORIS is present in T-ALL cell lines as well as in cell lines derived from several solid tumors overexpressing NOTCH3. Moreover, BORIS targets NOTCH3 promoter in cancer cells and it is able to induce and to maintain a permissive/active chromatin conformation. Importantly, the association between NOTCH3 overexpression and BORIS presence was confirmed in primary T-ALL samples from patients at the onset of the disease. Overall, our results provide novel insights into the determinants of NOTCH3 overexpression in cancer cells, by revealing a key role for BORIS as the main mediator of transcriptional deregulation of NOTCH3., (Copyright © 2014 Elsevier B.V. All rights reserved.)
- Published
- 2014
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56. M2 muscarinic receptor activation regulates Schwann cell differentiation and myelin organization.
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Uggenti C, De Stefano ME, Costantino M, Loreti S, Pisano A, Avallone B, Talora C, Magnaghi V, and Tata AM
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- Animals, Arecoline analogs & derivatives, Arecoline pharmacology, Axons drug effects, Axons physiology, Axons ultrastructure, Cells, Cultured, Mice, Knockout, Myelin Proteins metabolism, Myelin Sheath drug effects, Myelin Sheath ultrastructure, Nerve Degeneration pathology, Nerve Degeneration physiopathology, Peripheral Nervous System Agents pharmacology, RNA, Messenger genetics, RNA, Messenger metabolism, Rats, Wistar, Receptor, Muscarinic M2 agonists, Receptor, Muscarinic M2 genetics, Receptor, Muscarinic M4 genetics, Receptor, Muscarinic M4 metabolism, Schwann Cells drug effects, Schwann Cells ultrastructure, Sciatic Nerve drug effects, Sciatic Nerve physiology, Sciatic Nerve physiopathology, Sciatic Nerve ultrastructure, Signal Transduction drug effects, Transcription Factors metabolism, Myelin Sheath physiology, Neurogenesis drug effects, Receptor, Muscarinic M2 metabolism, Schwann Cells physiology
- Abstract
Glial cells express acetylcholine receptors. In particular, rat Schwann cells express different muscarinic receptor subtypes, the most abundant of which is the M2 subtype. M2 receptor activation causes a reversible arrest of the cell cycle. This negative effect on Schwann cell proliferation suggests that these cells may possibly progress into a differentiating program. In this study we analyzed the in vitro modulation, by the M2 agonist arecaidine, of transcription factors and specific signaling pathways involved in Schwann cell differentiation. The arecaidine-induced M2 receptor activation significantly upregulates transcription factors involved in the promyelinating phase (e.g., Sox10 and Krox20) and downregulates proteins involved in the maintenance of the undifferentiated state (e.g., c-jun, Notch-1, and Jagged-1). Furthermore, arecaidine stimulation significantly increases the expression of myelin proteins, which is accompanied by evident changes in cell morphology, as indicated by electron microscopy analysis, and by substantial cellular re-distribution of actin and cell adhesion molecules. Moreover, ultrastructural and morphometric analyses on sciatic nerves of M2/M4 knockout mice show numerous degenerating axons and clear alterations in myelin organization compared with wild-type mice. Therefore, our data demonstrate that acetylcholine mediates axon-glia cross talk, favoring Schwann cell progression into a differentiated myelinating phenotype and contributing to compact myelin organization., (© 2013 Wiley Periodicals, Inc.)
- Published
- 2014
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57. Loss of Notch1-dependent p21(Waf1/Cip1) expression influences the Notch1 outcome in tumorigenesis.
- Author
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Cialfi S, Palermo R, Manca S, De Blasio C, Vargas Romero P, Checquolo S, Bellavia D, Uccelletti D, Saliola M, D'Alessandro A, Zolla L, Gulino A, Screpanti I, and Talora C
- Subjects
- Apoptosis drug effects, Arsenites toxicity, Carcinogenesis drug effects, Carcinogenesis pathology, Cell Cycle Proteins metabolism, Cell Line, Cell Proliferation drug effects, Cyclin-Dependent Kinase Inhibitor p21 metabolism, F-Box Proteins metabolism, F-Box-WD Repeat-Containing Protein 7, Humans, Keratinocytes drug effects, Keratinocytes pathology, MicroRNAs metabolism, NF-E2-Related Factor 2 metabolism, Oxidative Stress drug effects, Proto-Oncogene Proteins c-myc genetics, Reactive Oxygen Species metabolism, Receptor, Notch1 genetics, Ubiquitin-Protein Ligases metabolism, Carcinogenesis metabolism, Cyclin-Dependent Kinase Inhibitor p21 genetics, Receptor, Notch1 metabolism
- Abstract
Notch signaling plays a complex role in carcinogenesis, and its signaling pathway has both tumor-suppressor and oncogenic components. In this study we investigated the effects of reactive oxygen species (ROS) on Notch1 signaling outcome in keratinocyte biology. We demonstrate that Notch1 function contributes to the arsenic-induced keratinocyte transformation. We found that acute exposure to arsenite increases oxidative stress and inhibits proliferation of keratinocyte cells by upregulation of p21(waf1/Cip1). The necessity of p21(waf1/Cip1) for arsenite-induced cell death was demonstrated by targeted downregulation of p21(waf1/Cip1) by using RNA interference. We further demonstrated that on acute exposure to arsenite, p21(waf1/Cip1) is upregulated and Notch1 downmodulated, whereas on chronic exposure to arsenite, malignant progression of arsenite-treated keratinocytes cells was accompanied by regained expression and activity of Notch1. Notch1 activity in arsenite-transformed keratinocytes inhibits arsenite-induced upregulation of p21(waf1/Cip1) by sustaining c-myc expression. We further demonstrated that c-myc collaborates with Nrf2, a key regulator for the maintenance of redox homeostasis, to promote metabolic activities that support cell proliferation and cytoprotection. Therefore, Notch1-mediated repression of p21(waf1/Cip1) expression results in the inhibition of cell death and keratinocytes transformation. Our results not only demonstrate that sustained Notch1 expression is at least one key event implicated in the arsenite human skin carcinogenic effect, but also may provide mechanistic insights into the molecular aspects that determine whether Notch signaling will be either oncogenic or tumor suppressive.
- Published
- 2014
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58. Inhibition of microbial growth by carbon nanotube networks.
- Author
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Olivi M, Zanni E, De Bellis G, Talora C, Sarto MS, Palleschi C, Flahaut E, Monthioux M, Rapino S, Uccelletti D, and Fiorito S
- Subjects
- Anti-Infective Agents chemical synthesis, Anti-Infective Agents pharmacology, Candida albicans drug effects, Candida albicans metabolism, Microscopy, Electron, Scanning, Nanotubes, Carbon toxicity, Pseudomonas aeruginosa drug effects, Pseudomonas aeruginosa metabolism, Reactive Oxygen Species metabolism, Staphylococcus aureus drug effects, Staphylococcus aureus metabolism, Anti-Infective Agents chemistry, Nanotubes, Carbon chemistry
- Abstract
In the last years carbon nanotubes have attracted increasing attention for their potential applications in the biomedical field as diagnostic and therapeutic nano tools. Here we investigate the antimicrobial activity of different fully characterized carbon nanotube types (single walled, double walled and multi walled) on representative pathogen species: Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the opportunistic fungus Candida albicans. Our results show that all the carbon nanotube types possess a highly significant antimicrobial capacity, even though they have a colony forming unit capacity and induction of oxidative stress in all the microbial species to a different extent. Moreover, scanning electron microscopy analysis revealed that the microbial cells were wrapped or entrapped by carbon nanotube networks. Our data taken together suggest that the reduced capacity of microbial cells to forming colonies and their oxidative response could be related to the cellular stress induced by the interactions of pathogens with the CNT network.
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- 2013
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59. The translation factor eIF6 is a Notch-dependent regulator of cell migration and invasion.
- Author
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Benelli D, Cialfi S, Pinzaglia M, Talora C, and Londei P
- Subjects
- Cell Line, Tumor, Female, Humans, Ovarian Neoplasms pathology, Precursor Cell Lymphoblastic Leukemia-Lymphoma pathology, Signal Transduction, Cell Movement, Neoplasm Invasiveness, Peptide Initiation Factors physiology, Receptor, Notch1 metabolism
- Abstract
A growing body of evidence indicates that protein factors controlling translation play an important role in tumorigenesis. The protein known as eIF6 is a ribosome anti-association factor that has been implicated in translational initiation and in ribosome synthesis. Over-expression of eIF6 is observed in many natural tumours, and causes developmental and differentiation defects in certain animal models. Here we show that the transcription of the gene encoding eIF6 is modulated by the receptor Notch-1, a protein involved in embryonic development and cell differentiation, as well as in many neoplasms. Inhibition of Notch-1 signalling by γ-secretase inhibitors slowed down cell-cycle progression and reduced the amount of eIF6 in lymphoblastoid and ovarian cancer cell lines. Cultured ovarian cancer cell lines engineered to stably over-expressing eIF6 did not show significant changes in proliferation rate, but displayed an enhanced motility and invasive capacity. Inhibition of Notch-1 signalling in the cells over-expressing eIF6 was effective in slowing down the cell cycle, but did not reduce cell migration and invasion. On the whole, the results suggest that eIF6 is one of the downstream effectors of Notch-1 in the pathway that controls cell motility and invasiveness.
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- 2012
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60. Oxidative stress activation of miR-125b is part of the molecular switch for Hailey-Hailey disease manifestation.
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Manca S, Magrelli A, Cialfi S, Lefort K, Ambra R, Alimandi M, Biolcati G, Uccelletti D, Palleschi C, Screpanti I, Candi E, Melino G, Salvatore M, Taruscio D, and Talora C
- Subjects
- Base Sequence, Cell Differentiation, Cell Proliferation, Cells, Cultured, DNA Primers genetics, Down-Regulation, Humans, Keratinocytes metabolism, Keratinocytes pathology, Models, Biological, Oxidative Stress, Pemphigus, Benign Familial pathology, Receptor, Notch1 genetics, Receptor, Notch1 metabolism, Transcription Factors genetics, Transcription Factors metabolism, Tumor Suppressor Proteins genetics, Tumor Suppressor Proteins metabolism, MicroRNAs genetics, MicroRNAs metabolism, Pemphigus, Benign Familial genetics, Pemphigus, Benign Familial metabolism
- Abstract
Hailey-Hailey disease (HHD) is an autosomal dominant disorder characterized by suprabasal cutaneous cell separation (acantholysis) leading to the development of erosive and oozing skin lesion. Micro RNAs (miRNAs) are endogenous post-transcriptional modulators of gene expression with critical functions in health and disease. Here, we evaluated whether the expression of specific miRNAs may play a role in the pathogenesis of HHD. Here, we report that miRNAs are expressed in a non-random manner in Hailey-Hailey patients. miR-125b appeared a promising candidate for playing a role in HHD manifestation. Both Notch1 and p63 are part of a regulatory signalling whose function is essential for the control of keratinocyte proliferation and differentiation and of note, the expression of both Notch1 and p63 is downregulated in HHD-derived keratinocytes. We found that both Notch1 and p63 expression is strongly suppressed by miR-125b expression. Additionally, we found that miR-125b expression is increased by an oxidative stress-dependent mechanism. Our data suggest that oxidative stress-mediated induction of miR-125b plays a specific role in the pathogenesis of HHD by regulating the expression of factors playing an important role in keratinocyte proliferation and differentiation., (© 2011 John Wiley & Sons A/S.)
- Published
- 2011
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61. Notch signaling and diseases: an evolutionary journey from a simple beginning to complex outcomes.
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Talora C, Campese AF, Bellavia D, Felli MP, Vacca A, Gulino A, and Screpanti I
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- Animals, Autoimmunity, Humans, Neoplasms metabolism, Biological Evolution, Disease, Receptors, Notch metabolism, Signal Transduction
- Abstract
Notch signaling pathway regulates a wide variety of cellular processes during development and it also plays a crucial role in human diseases. This important link is firmly established in cancer, since a rare T-ALL-associated genetic lesion has been initially reported to result in deletion of Notch1 ectodomain and constitutive activation of its intracellular region. Interestingly, the cellular response to Notch signaling can be extremely variable depending on the cell type and activation context. Notch signaling triggers signals implicated in promoting carcinogenesis and autoimmune diseases, whereas it can also sustain responses that are critical to suppress carcinogenesis and to negatively regulate immune response. However, Notch signaling induces all these effects via an apparently simple signal transduction pathway, diversified into a complex network along evolution from Drosophila to mammals. Indeed, an explanation of this paradox comes from a number of evidences accumulated during the last few years, which dissected the intrinsic canonical and non-canonical components of the Notch pathway as well as several modulatory extrinsic signaling events. The identification of these signals has shed light onto the mechanisms whereby Notch and other pathways collaborate to induce a particular cellular phenotype. In this article, we review the role of Notch signaling in cells as diverse as T lymphocytes and epithelial cells of the epidermis, with the main focus on understanding the mechanisms of Notch versatility.
- Published
- 2008
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62. Human papilloma virus-dependent HMGA1 expression is a relevant step in cervical carcinogenesis.
- Author
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Mellone M, Rinaldi C, Massimi I, Petroni M, Veschi V, Talora C, Truffa S, Stabile H, Frati L, Screpanti I, Gulino A, and Giannini G
- Subjects
- Cell Line, Tumor, Cell Proliferation, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Female, Gene Expression Profiling, HMGA1a Protein metabolism, HeLa Cells, Humans, Oncogene Proteins, Viral genetics, Oncogene Proteins, Viral metabolism, Papillomavirus Infections virology, RNA, Messenger genetics, Receptor, Notch1 metabolism, Reverse Transcriptase Polymerase Chain Reaction methods, Tumor Suppressor Protein p53 metabolism, Uterine Cervical Neoplasms pathology, Cell Transformation, Viral genetics, Gene Expression Regulation, Neoplastic, HMGA1a Protein genetics, Papillomaviridae genetics, Papillomavirus Infections genetics, Uterine Cervical Neoplasms genetics, Uterine Cervical Neoplasms virology
- Abstract
HMGA1 is a member of a small family of architectural transcription factors involved in the coordinate assembly of multiprotein complexes referred to as enhanceosomes. In addition to their role in cell proliferation, differentiation, and development, high-mobility group proteins of the A type (HMGA) family members behave as transforming protoncogenes either in vitro or in animal models. Recent reports indicated that HMGA1 might counteract p53 pathway and provided an interesting hint on the mechanisms determining HMGA's transforming potential. HMGA1 expression is deregulated in a very large array of human tumors, including cervical cancer, but very limited information is available on the molecular mechanisms leading to HMGA1 deregulation in cancer cells. Here, we report that HMGA1 expression is sustained by human papilloma virus (HPV) E6/E7 proteins in cervical cancer, as demonstrated by either E6/E7 overexpression or by repression through RNA interference. Knocking down HMGA1 expression by means of RNA interference, we also showed that it is involved in cell proliferation and contributes to p53 inactivation in this type of neoplasia. Finally, we show that HMGA1 is necessary for the full expression of HPV18 E6 and E7 oncoproteins thus establishing a positive autoregulatory loop between HPV E6/E7 and HMGA1 expression.
- Published
- 2008
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63. Notch3 and the Notch3-upregulated RNA-binding protein HuD regulate Ikaros alternative splicing.
- Author
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Bellavia D, Mecarozzi M, Campese AF, Grazioli P, Talora C, Frati L, Gulino A, and Screpanti I
- Subjects
- Alternative Splicing genetics, Animals, Blotting, Western, Cell Differentiation physiology, Cell Proliferation, Chromatin Immunoprecipitation, DNA Primers, ELAV-Like Protein 4, Electrophoretic Mobility Shift Assay, Flow Cytometry, Gene Expression Regulation genetics, Ikaros Transcription Factor genetics, Luciferases, Membrane Glycoproteins metabolism, Mice, RNA Interference, Receptor, Notch3, Receptors, Antigen, T-Cell, alpha-beta metabolism, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction genetics, T-Lymphocytes metabolism, Alternative Splicing physiology, ELAV Proteins metabolism, Gene Expression Regulation physiology, Ikaros Transcription Factor physiology, Receptors, Notch metabolism, Signal Transduction physiology, T-Lymphocytes cytology
- Abstract
Constitutive activation of the transmembrane receptor, Notch3, and loss of function of the hematopoietic transcription repressor, Ikaros (IK), play direct roles in T-cell differentiation and leukemogenesis that are dependent on pre-T-cell receptor (pre-TCR) signaling. We demonstrate the occurrence of crosstalk between Notch3 and IK that results in transcriptional regulation of the gene encoding the pTalpha chain of the pre-TCR. We also show that, in the presence of the pre-TCR, constitutive activation of Notch3 in thymocytes causes increased expression of dominantnegative non-DNA-binding IK isoforms, which are able to restrain the IK inhibition of Notch3's transcriptional activation of pTalpha. This effect appears to be mediated by Notch3's pre-TCR-dependent upregulation of the RNA-binding protein, HuD. Notch3 signaling thus appears to play a critical role in the diminished IK activity described in several lymphoid leukemias. By exerting transcription-activating and transcription-repressing effects on the pTalpha promoter, Notch3 and IK cooperate in the fine-tuning of pre-TCR expression and function, which has important implications for the regulation of thymocyte differentiation and proliferation.
- Published
- 2007
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64. Cross talk among Notch3, pre-TCR, and Tal1 in T-cell development and leukemogenesis.
- Author
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Talora C, Cialfi S, Oliviero C, Palermo R, Pascucci M, Frati L, Vacca A, Gulino A, and Screpanti I
- Subjects
- Animals, Basic Helix-Loop-Helix Transcription Factors metabolism, Cell Transformation, Neoplastic metabolism, Cyclin D1 genetics, Cyclin D1 metabolism, Extracellular Signal-Regulated MAP Kinases genetics, Extracellular Signal-Regulated MAP Kinases metabolism, Gene Expression Regulation, Leukemic genetics, Humans, Leukemia metabolism, Mice, Mice, Mutant Strains, Multiprotein Complexes genetics, Multiprotein Complexes metabolism, Neoplasm Proteins metabolism, Promoter Regions, Genetic genetics, Proto-Oncogene Proteins metabolism, Receptor, Notch3, Receptors, Antigen, T-Cell genetics, Receptors, Antigen, T-Cell metabolism, Receptors, Notch metabolism, T-Cell Acute Lymphocytic Leukemia Protein 1, T-Lymphocytes metabolism, T-Lymphocytes pathology, Basic Helix-Loop-Helix Transcription Factors genetics, Cell Differentiation genetics, Cell Transformation, Neoplastic genetics, Leukemia genetics, Neoplasm Proteins genetics, Proto-Oncogene Proteins genetics, Receptors, Notch genetics, Signal Transduction genetics
- Abstract
Integrated pathways are believed to determine hematopoietic cell fate and/or neoplastic transformation. Notch signaling has been shown to regulate T-cell differentiation and leukemogenesis. However, specific target genes and molecular partners are not fully elucidated. We show that Notch3 activation sustains aberrant SCL/Tal1 overexpression and phosphorylation in mature thymocytes. Furthermore, we define the role of SCL/Tal1 as a component of an activator complex, including phosphorylated Tal1 and Sp1, that specifically enhances cyclin D1 expression and demonstrate that Tal1/Sp1 specifically co-occupy the D1 promoter in vivo, only in the presence of pre-T-cell receptor (TCR). We therefore conclude not only that cyclin D1 is a target of the Tal1/Sp1 complex, but also that Notch3-dependent activation of pre-TCR/ERK signaling regulates SCL/Tal1 function.
- Published
- 2006
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65. The Golgi Ca2+-ATPase KlPmr1p function is required for oxidative stress response by controlling the expression of the heat-shock element HSP60 in Kluyveromyces lactis.
- Author
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Uccelletti D, Farina F, Pinton P, Goffrini P, Mancini P, Talora C, Rizzuto R, and Palleschi C
- Subjects
- Amino Acid Sequence, Calcium metabolism, Calcium-Transporting ATPases genetics, Cell Wall metabolism, Gene Expression Regulation, Fungal, Glycosylation, Kluyveromyces genetics, Microscopy, Electron, Transmission, Mitochondria metabolism, Mitochondria ultrastructure, Molecular Sequence Data, Mutation, Sequence Homology, Amino Acid, Calcium-Transporting ATPases physiology, Chaperonin 60 metabolism, Golgi Apparatus physiology, Kluyveromyces physiology, Oxidative Stress
- Abstract
The Golgi P-type Ca2+-ATPase, Pmr1p, is the major player for calcium homeostasis in yeast. The inactivation of KlPMR1 in Kluyveromyces lactis leads to high pleiotropic phenotypes that include reduced glycosylation, cell wall defects, and alterations of mitochondrial metabolism. In this article we found that cells lacking KlPmr1p have a morphologically altered mitochondrial network and that mitochondria (m) from Klpmr1delta cells accumulate Ca2+ more slowly and reach a lower [Ca2+]m level, when exposed to [Ca2+] < 5 microM, than wild-type cells. The Klpmr1delta cells also exhibit traits of ongoing oxidative stress and present hyperphosphorylation of KlHog1p, the hallmark for the activation of stress response pathways. The mitochondrial chaperone KlHsp60 acts as a multicopy suppressor of phenotypes that occur in cells lacking the Ca2+-ATPase, including relief from oxidative stress and recovery of cell wall thickness and functionality. Inhibition of KlPMR1 function decreases KlHSP60 expression at both mRNA and protein levels. Moreover, KlPRM1 loss of function correlates with both decreases in HSF DNA binding activity and KlHSP60 expression. We suggest a role for KlPMR1 in HSF DNA binding activity, which is required for proper KlHSP60 expression, a key step in oxidative stress response.
- Published
- 2005
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66. Constitutively active Notch1 induces growth arrest of HPV-positive cervical cancer cells via separate signaling pathways.
- Author
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Talora C, Cialfi S, Segatto O, Morrone S, Kim Choi J, Frati L, Paolo Dotto G, Gulino A, and Screpanti I
- Subjects
- Cell Line, Tumor, Cell Proliferation drug effects, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Female, Humans, Immunoglobulin J Recombination Signal Sequence-Binding Protein, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Nuclear Proteins genetics, Nuclear Proteins metabolism, Oncogene Proteins, Viral genetics, Oncogene Proteins, Viral metabolism, Papillomaviridae isolation & purification, Receptor, Notch1, Receptors, Cell Surface genetics, TCF Transcription Factors, Tamoxifen pharmacology, Transcription Factor 7-Like 1 Protein, Transcription Factor AP-1 metabolism, Transcription Factors genetics, Transcription Factors metabolism, Papillomaviridae physiology, Receptors, Cell Surface physiology, Signal Transduction, Transcription Factors physiology, Uterine Cervical Neoplasms metabolism, Uterine Cervical Neoplasms virology
- Abstract
Notch signaling plays a key role in cell-fate determination and differentiation in different organisms and cell types. Several reports suggest that Notch signaling may be involved in neoplastic transformation. However, in primary keratinocytes, Notch1 can function as a tumor suppressor. Similarly, in HPV-positive cervical cancer cells, constitutively active Notch1 signaling was found to cause growth suppression. Activated Notch1 in these cells represses viral E6/E7 expression through AP-1 down-modulation, resulting in increased p53 expression and a block of pRb hyperphosphorylation. Here we show that in cervical cancer cell lines in which Notch1 ability to repress AP-1 activity is impaired, Notch1-enforced expression elicits an alternative pathway leading to growth arrest. Indeed, activated Notch1 signaling suppresses activity of the helix-loop-helix transcription factor E47, via ERK1/2 activation, resulting in inhibition of cell cycle progression. Moreover, we found that RBP-Jkappa-dependent Notch signaling is specifically repressed in cervical cancer cells and this repression could provide one such mechanism that needs to be activated for cervical carcinogenesis. Finally, we show that inhibition of endogenous Notch1 signaling, although results in a proliferative advantage, sensitizes cervical cancer cell lines to drug-induced apoptosis. Together, our results provide novel molecular insights into Notch1-dependent growth inhibitory effects, counteracting the transforming potential of HPV.
- Published
- 2005
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67. PKC theta mediates pre-TCR signaling and contributes to Notch3-induced T-cell leukemia.
- Author
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Felli MP, Vacca A, Calce A, Bellavia D, Campese AF, Grillo R, Di Giovine M, Checquolo S, Talora C, Palermo R, Di Mario G, Frati L, Gulino A, and Screpanti I
- Subjects
- Animals, Cell Membrane, Isoenzymes pharmacokinetics, Lymphoma, T-Cell, Membrane Glycoproteins, Mice, Mice, Transgenic, NF-kappa B genetics, NF-kappa B pharmacology, Protein Kinase C pharmacokinetics, Protein Kinase C-theta, Receptor, Notch3, Receptor, Notch4, Receptors, Antigen, T-Cell, alpha-beta, Receptors, Notch, Signal Transduction, Thymus Gland cytology, Zinc Fingers, Isoenzymes genetics, Isoenzymes pharmacology, Leukemia, T-Cell genetics, Leukemia, T-Cell physiopathology, Protein Kinase C genetics, Protein Kinase C pharmacology, Proto-Oncogene Proteins genetics, Proto-Oncogene Proteins pharmacology, Receptors, Cell Surface genetics
- Abstract
Protein kinase (PK)C theta is a critical regulator of mature T-cell activation and proliferation, being implicated in TCR-triggered nuclear factor (NF)-kappa B activation and providing important survival signals to leukemic T cells. We previously showed that overexpression of pT alpha/pre-TCR and constitutive activation of NF-kappa B characterize the T-cell leukemia/lymphoma developing in Notch3-IC transgenic mice. We report here that PKC theta is a downstream target of Notch3 signaling and that its activation and membrane translocation require a functional pre-TCR in order to trigger NF-kappa B activation in thymocytes and lymphoma cells of transgenic mice. Furthermore, deletion of PKC theta in Notch3-IC transgenic mice reduces the incidence of leukemia, correlating with decreased NF-kappa B activation. This paper therefore suggests that PKC theta mediates the activation of NF-kappa B by pre-TCR in immature thymocytes and contributes to the development of Notch3-dependent T-cell lymphoma.
- Published
- 2005
- Full Text
- View/download PDF
68. High commitment of embryonic keratinocytes to terminal differentiation through a Notch1-caspase 3 regulatory mechanism.
- Author
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Okuyama R, Nguyen BC, Talora C, Ogawa E, Tommasi di Vignano A, Lioumi M, Chiorino G, Tagami H, Woo M, and Dotto GP
- Subjects
- Animals, Animals, Newborn, Caspase 3, Caspases genetics, Cell Lineage genetics, Cells, Cultured, Epidermal Cells, Fetus, In Vitro Techniques, Keratinocytes cytology, Mice, Protein Kinase C genetics, Protein Kinase C metabolism, Protein Kinase C-delta, Receptor, Notch1, Receptors, Cell Surface genetics, Signal Transduction drug effects, Signal Transduction physiology, Up-Regulation genetics, Caspases metabolism, Cell Differentiation genetics, Epidermis embryology, Epidermis growth & development, Keratinocytes metabolism, Receptors, Cell Surface metabolism, Transcription Factors
- Abstract
Embryonic cells are expected to possess high growth/differentiation potential, required for organ morphogenesis and expansion during development. However, little is known about the intrinsic properties of embryonic epithelial cells due to difficulties in their isolation and cultivation. We report here that pure keratinocyte populations from E15.5 mouse embryos commit irreversibly to differentiation much earlier than newborn cells. Notch signaling, which promotes keratinocyte differentiation, is upregulated in embryonic keratinocyte and epidermis, and elevated caspase 3 expression, which we identify as a transcriptional Notch1 target, accounts in part for the high commitment of embryonic keratinocytes to terminal differentiation. In vivo, lack of caspase 3 results in increased proliferation and decreased differentiation of interfollicular embryonic keratinocytes, together with decreased activation of PKC-delta, a caspase 3 substrate which functions as a positive regulator of keratinocyte differentiation. Thus, a Notch1-caspase 3 regulatory mechanism underlies the intrinsically high commitment of embryonic keratinocytes to terminal differentiation.
- Published
- 2004
- Full Text
- View/download PDF
69. Pre-TCR-triggered ERK signalling-dependent downregulation of E2A activity in Notch3-induced T-cell lymphoma.
- Author
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Talora C, Campese AF, Bellavia D, Pascucci M, Checquolo S, Groppioni M, Frati L, von Boehmer H, Gulino A, and Screpanti I
- Subjects
- Animals, Down-Regulation, Helix-Loop-Helix Motifs, Inhibitor of Differentiation Protein 1, Mice, Proto-Oncogene Proteins metabolism, Receptor, Notch3, Receptor, Notch4, Receptors, Antigen, T-Cell metabolism, Receptors, Cell Surface metabolism, Receptors, Notch, Signal Transduction physiology, Lymphoma, T-Cell metabolism, Mitogen-Activated Protein Kinases metabolism, Proto-Oncogene Proteins genetics, Receptors, Cell Surface genetics, Repressor Proteins, Transcription Factors metabolism
- Abstract
Notch and basic helix-loop-helix E2A pathways specify cell fate and regulate neoplastic transformation in a variety of cell types. Whereas Notch enhances tumorigenesis, E2A suppresses it. However, whether and how Notch and E2A interact functionally in an integrative mechanism for regulating neoplastic transformation remains to be understood. It has been shown that Notch3-induced T-cell leukaemia is abrogated by the inactivation of pTalpha/pre-T-cell antigen receptor (pre-TCR). We report here that Notch3-induced transcriptional activation of pTalpha/pre-TCR is responsible for the downregulation of E2A DNA binding and transcriptional activity. Further, the E2A messenger RNA and protein levels remain unaltered but the E2A inhibitor Id1 expression is augmented in thymocytes and T lymphoma cells derived from Notch3 transgenic mice. The increase in Id1 expression is achieved by pre-TCR-induced extracellular-signalling-regulated kinase 1/2. These observations support a model in which the upregulation of pre-TCR signalling seems to be the prerequi-site for Notch3-induced inhibition of E2A, thus leading to the development of lymphoma in Notch3 transgenic mice.
- Published
- 2003
- Full Text
- View/download PDF
70. Specific down-modulation of Notch1 signaling in cervical cancer cells is required for sustained HPV-E6/E7 expression and late steps of malignant transformation.
- Author
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Talora C, Sgroi DC, Crum CP, and Dotto GP
- Subjects
- Cell Transformation, Neoplastic, DNA-Binding Proteins metabolism, Down-Regulation, Female, Genes, Viral, Humans, Immunoglobulin J Recombination Signal Sequence-Binding Protein, Membrane Proteins genetics, Papillomaviridae genetics, Papillomavirus Infections etiology, Papillomavirus Infections metabolism, Papillomavirus Infections pathology, Papillomavirus Infections virology, RNA, Messenger genetics, RNA, Messenger metabolism, RNA, Neoplasm genetics, RNA, Neoplasm metabolism, Receptor, Notch1, Receptor, Notch2, Receptors, Cell Surface genetics, Receptors, Cell Surface metabolism, Signal Transduction, Transcription Factor AP-1 metabolism, Tumor Cells, Cultured, Tumor Virus Infections etiology, Tumor Virus Infections metabolism, Tumor Virus Infections pathology, Tumor Virus Infections virology, Uterine Cervical Neoplasms etiology, Uterine Cervical Neoplasms pathology, Membrane Proteins metabolism, Nuclear Proteins, Papillomaviridae pathogenicity, Transcription Factors, Uterine Cervical Neoplasms metabolism, Uterine Cervical Neoplasms virology
- Abstract
The Notch family of cell surface receptors plays a key role in cell-fate determination and differentiation, functioning in a cell- and context-specific manner. In mammalian cells, Notch activation is generally thought to maintain stem cell potential and inhibit differentiation, thereby promoting carcinogenesis. However, in other contexts such as primary epithelial cells (keratinocytes), increased Notch activity causes exit from the cell cycle and/or commitment to differentiation. We now report that expression of the endogenous Notch1 gene is markedly reduced in a panel of cervical carcinoma cells whereas expression of Notch2 remains elevated, and Notch1 expression is similarly reduced or absent in invasive cervical cancers. Conversely, expression of activated Notch1 causes strong growth inhibition of HPV-positive, but not HPV-negative, cervical carcinoma cells, but exerts no such effects on other epithelial tumor cells. Increased Notch1 signaling, but not Notch2, causes a dramatic down-modulation of HPV-driven transcription of the E6/E7 viral genes, through suppression of AP-1 activity by up-regulation of the Fra-1 family member and decreased c-Fos expression. Thus, Notch1 exerts specific protective effects against HPV-induced transformation through suppression of E6/E7 expression, and down-modulation of Notch1 expression is likely to play an important role in late stages of HPV-induced carcinogenesis.
- Published
- 2002
- Full Text
- View/download PDF
71. Cross talk among calcineurin, Sp1/Sp3, and NFAT in control of p21(WAF1/CIP1) expression in keratinocyte differentiation.
- Author
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Santini MP, Talora C, Seki T, Bolgan L, and Dotto GP
- Subjects
- Animals, Binding Sites, Cell Differentiation genetics, Cyclin-Dependent Kinase Inhibitor p21, Cyclins genetics, Cyclosporine pharmacology, Filaggrin Proteins, Genes, Reporter, Green Fluorescent Proteins, Intermediate Filament Proteins biosynthesis, Intermediate Filament Proteins genetics, Keratinocytes metabolism, Luminescent Proteins genetics, Macromolecular Substances, Membrane Proteins biosynthesis, Membrane Proteins genetics, Mice, Mice, Inbred SENCAR, NFATC Transcription Factors, Promoter Regions, Genetic drug effects, Protein Subunits, Sp3 Transcription Factor, Calcineurin physiology, Cyclins biosynthesis, DNA-Binding Proteins physiology, Gene Expression Regulation drug effects, Keratinocytes cytology, Nuclear Proteins, Sp1 Transcription Factor physiology, Transcription Factors physiology, Transcription, Genetic
- Abstract
Calcium functions as a trigger for the switch between epithelial cell growth and differentiation. We report here that the calcium/calmodulin-dependent phosphatase calcineurin is involved in this process. Treatment of primary mouse keratinocytes with cyclosporin A, an inhibitor of calcineurin activity, suppresses the expression of terminal differentiation markers and of p21(WAF1/Cip1) and p27(KIP1), two cyclin-dependent kinase inhibitors that are usually induced with differentiation. In parallel with down-modulation of the endogenous genes, suppression of calcineurin function blocks induction of the promoters for the p21(WAF1/Cip1) and loricrin differentiation marker genes, whereas activity of these promoters is enhanced by calcineurin overexpression. The calcineurin- responsive region of the p21 promoter maps to a 78-bp Sp1/Sp3-binding sequence next to the TATA box, and calcineurin induces activity of the p21 promoter through Sp1/Sp3-dependent transcription. We find that the endogenous NFAT-1 and -2 transcription factors, major downstream targets of calcineurin, associate with Sp1 in keratinocytes in a calcineurin-dependent manner, and calcineurin up-regulates Sp1/Sp3-dependent transcription and p21 promoter activity in synergism with NFAT1/2. Thus, our study reveals an important role for calcineurin in control of keratinocyte differentiation and p21 expression, and points to a so-far-unsuspected interconnection among this phosphatase, NFATs, and Sp1/Sp3-dependent transcription.
- Published
- 2001
- Full Text
- View/download PDF
72. Notch signaling is a direct determinant of keratinocyte growth arrest and entry into differentiation.
- Author
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Rangarajan A, Talora C, Okuyama R, Nicolas M, Mammucari C, Oh H, Aster JC, Krishna S, Metzger D, Chambon P, Miele L, Aguet M, Radtke F, and Dotto GP
- Subjects
- Animals, Cell Division physiology, Chromatin physiology, Cyclin-Dependent Kinase Inhibitor p21, Cyclins deficiency, Enzyme Inhibitors metabolism, Immunoglobulin J Recombination Signal Sequence-Binding Protein, Mice, Mice, Knockout, Morphogenesis, Receptor, Notch1, Receptor, Notch2, Recombinant Fusion Proteins metabolism, Repressor Proteins metabolism, Signal Transduction, Skin cytology, Transcription, Genetic, Transfection, Cell Differentiation physiology, Cyclins genetics, Cyclins metabolism, DNA-Binding Proteins metabolism, Keratinocytes cytology, Keratinocytes physiology, Membrane Proteins metabolism, Nuclear Proteins, Receptors, Cell Surface metabolism, Transcription Factors
- Abstract
The role of Notch signaling in growth/differentiation control of mammalian epithelial cells is still poorly defined. We show that keratinocyte-specific deletion of the Notch1 gene results in marked epidermal hyperplasia and deregulated expression of multiple differentiation markers. In differentiating primary keratinocytes in vitro endogenous Notch1 is required for induction of p21WAF1/Cip1 expression, and activated Notch1 causes growth suppression by inducing p21WAF1/Cip1 expression. Activated Notch1 also induces expression of 'early' differentiation markers, while suppressing the late markers. Induction of p21WAF1/Cip1 expression and early differentiation markers occur through two different mechanisms. The RBP-Jkappa protein binds directly to the endogenous p21 promoter and p21 expression is induced specifically by activated Notch1 through RBP-Jkappa-dependent transcription. Expression of early differentiation markers is RBP-Jkappa-independent and can be induced by both activated Notch1 and Notch2, as well as the highly conserved ankyrin repeat domain of the Notch1 cytoplasmic region. Thus, Notch signaling triggers two distinct pathways leading to keratinocyte growth arrest and differentiation.
- Published
- 2001
- Full Text
- View/download PDF
73. A PKC-eta/Fyn-dependent pathway leading to keratinocyte growth arrest and differentiation.
- Author
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Cabodi S, Calautti E, Talora C, Kuroki T, Stein PL, and Dotto GP
- Subjects
- Animals, Cell Division, Cells, Cultured, Cyclin-Dependent Kinases metabolism, Cyclins antagonists & inhibitors, Cyclins metabolism, Enzyme Activation, ErbB Receptors antagonists & inhibitors, ErbB Receptors metabolism, Fibroblasts cytology, Fibroblasts enzymology, Fibroblasts metabolism, Gene Deletion, Isoenzymes antagonists & inhibitors, Isoenzymes genetics, Keratinocytes metabolism, Mice, Mitosis, Organ Specificity, Protein Binding, Protein Kinase C antagonists & inhibitors, Protein Kinase C genetics, Proto-Oncogene Proteins genetics, Proto-Oncogene Proteins c-fyn, Recombinant Proteins antagonists & inhibitors, Recombinant Proteins metabolism, Skin, Transglutaminases metabolism, Cell Differentiation, Isoenzymes metabolism, Keratinocytes cytology, Keratinocytes enzymology, Protein Kinase C metabolism, Proto-Oncogene Proteins metabolism, Signal Transduction
- Abstract
Growth control of epithelial cells differs substantially from other cell types. Activation of Fyn, a Src kinase family member, is required for normal keratinocyte differentiation. We report that increased Fyn activity by itself suppresses growth of keratinocytes, but not dermal fibroblasts, through downmodulation of EGF receptor (EGFR) signaling. Protein kinase C-eta has also been implicated in keratinocyte growth/differentiation control. We show that growth suppression of keratinocytes by PKC-eta depends mostly on Fyn. PKC-eta activity is both necessary and sufficient for Fyn activation, PKC-eta and Fyn are found in association, and recombinant PKC-eta directly activates Fyn. Thus, our findings reveal a direct cross talk between PKC-eta and Fyn, which presides over the decision between keratinocyte (epithelial) cell growth and differentiation.
- Published
- 2000
- Full Text
- View/download PDF
74. Inhibition of ErbB-2 mitogenic and transforming activity by RALT, a mitogen-induced signal transducer which binds to the ErbB-2 kinase domain.
- Author
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Fiorentino L, Pertica C, Fiorini M, Talora C, Crescenzi M, Castellani L, Alemà S, Benedetti P, and Segatto O
- Subjects
- 3T3 Cells, Amino Acid Sequence, Animals, Breast Neoplasms genetics, Breast Neoplasms metabolism, Cell Cycle, Cell Division, Enzyme Activation, Gene Expression Regulation, Intracellular Signaling Peptides and Proteins, Mice, Mitogen-Activated Protein Kinases metabolism, Mitogens chemistry, Mitogens metabolism, Molecular Sequence Data, Phosphorylation, Protein Binding, Proteins chemistry, Proteins genetics, Rats, Receptor, ErbB-2 chemistry, Receptor, ErbB-2 metabolism, Recombinant Fusion Proteins metabolism, Two-Hybrid System Techniques, src Homology Domains, Carrier Proteins, Catalytic Domain, Cell Transformation, Neoplastic, Mitogens antagonists & inhibitors, Proteins metabolism, Receptor, ErbB-2 antagonists & inhibitors, Signal Transduction
- Abstract
The product of rat gene 33 was identified as an ErbB-2-interacting protein in a two-hybrid screen employing the ErbB-2 juxtamembrane and kinase domains as bait. This interaction was reproduced in vitro with a glutathione S-transferase fusion protein spanning positions 282 to 395 of the 459-residue gene 33 protein. Activation of ErbB-2 catalytic function was required for ErbB-2-gene 33 physical interaction in living cells, whereas ErbB-2 autophosphorylation was dispensable. Expression of gene 33 protein was absent in growth-arrested NIH 3T3 fibroblasts but was induced within 60 to 90 min of serum stimulation or activation of the ErbB-2 kinase and decreased sharply upon entry into S phase. New differentiation factor stimulation of mitogen-deprived mammary epithelial cells also caused accumulation of gene 33 protein, which could be found in a complex with ErbB-2. Overexpression of gene 33 protein in mouse fibroblasts inhibited (i) cell proliferation driven by ErbB-2 but not by serum, (ii) cell transformation induced by ErbB-2 but not by Ras or Src, and (iii) sustained activation of ERK 1 and 2 by ErbB-2 but not by serum. The gene 33 protein may convey inhibitory signals downstream to ErbB-2 by virtue of its association with SH3-containing proteins, including GRB-2, which was found to associate with gene 33 protein in living cells. These data indicate that the gene 33 protein is a feedback inhibitor of ErbB-2 mitogenic function and a suppressor of ErbB-2 oncogenic activity. We propose that the gene 33 protein be renamed with the acronym RALT (receptor-associated late transducer).
- Published
- 2000
- Full Text
- View/download PDF
75. Roles in dimerization and blue light photoresponse of the PAS and LOV domains of Neurospora crassa white collar proteins.
- Author
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Ballario P, Talora C, Galli D, Linden H, and Macino G
- Subjects
- Amino Acid Sequence, Binding Sites, DNA-Binding Proteins genetics, Dimerization, Light, Molecular Sequence Data, Mutation, Neurospora crassa genetics, Phenotype, Transcription Factors genetics, DNA-Binding Proteins physiology, Fungal Proteins, Neurospora crassa physiology, Transcription Factors physiology
- Abstract
The genes coding for white collar-1 and white collar-2 (wc-1 and wc-2) have been isolated previously, and their products characterized as Zn-finger transcription factors involved in the control of blue light-induced genes. Here, we show that the PAS dimerization domains present in both proteins enable the WC-1 and WC-2 proteins to dimerize in vitro. Homodimers and heterodimers are formed between the white collar (WC) proteins. A computer analysis of WC-1 reveals a second domain, called LOV, also identified in NPH1, a putative blue light photoreceptor in plants and conserved in redox-sensitive proteins and in the phytochromes. The WC-1 LOV domain does not dimerize with canonical PAS domains, but it is able to self-dimerize. The isolation of three blind wc-1 strains, each with a single amino acid substitution only in the LOV domain, reveals that this region is essential for blue light responses in Neurospora. The demonstration that the WC-1 proteins in these LOV mutants are still able to self-dimerize suggests that this domain plays an additional role, essential in blue light signal transduction.
- Published
- 1998
- Full Text
- View/download PDF
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