51
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Murakami H, Arnheiter H. Sumoylation modulates transcriptional activity of MITF in a promoter-specific manner. ACTA ACUST UNITED AC 2006; 18:265-77. [PMID: 16029420 PMCID: PMC1351050 DOI: 10.1111/j.1600-0749.2005.00234.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The microphthalmia transcription factor MITF plays important roles in several cell lineages including retinal and neural crest-derived pigment cells. Previous reports have shown that besides its regulation at the transcriptional level, MITF is also regulated post-translationally by phosphorylation and ubiquitination which affect the protein's activity and stability. Here we demonstrate that in addition, MITF is modified in melanoma cells by small ubiquitin-like modifier (SUMO). In vitro assays further show that sumoylation occurs at two lysine residues, K182 and K316, and depends on SUMO E1 activating enzyme (SAE I/SAE II) and E2 conjugating enzyme (Ubc9). Interestingly, MITF with double lysine 182/316 to arginine mutations, although displaying normal DNA binding, stability and nuclear localization, shows a substantial increase in the transcriptional stimulation of promoters containing multiple but not single MITF binding sites. MITF containing the double lysine-to-arginine substitution also shows enhanced cooperation with Sox10 on the Dct promoter. We conclude that SUMO modification of MITF regulates the protein's transcriptional activity especially with respect to synergistic activation. The results suggest that sumoylation plays a significant role among the multiple mechanisms that regulate MITF during development and in adulthood.
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Affiliation(s)
- Hideki Murakami
- Mammalian Development Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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52
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Bosserhoff AK. Melanoma inhibitory activity (MIA): an important molecule in melanoma development and progression. ACTA ACUST UNITED AC 2006; 18:411-6. [PMID: 16280006 DOI: 10.1111/j.1600-0749.2005.00274.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cutaneous malignant melanoma is the leading cause of skin cancer death in industrialized countries. Melanoma development and progression are well defined by clinical and histopathological aspects; however, detailed analysis of molecular changes is still ongoing. The protein MIA, which is strongly expressed in melanoma cells but not in melanocytes, is likely to represent a key molecule regulating melanoma progression. Consistent with this, several in vitro and in vivo model systems indicate a direct involvement of MIA in melanoma migration and invasion, with recent studies suggesting a central role for MIA in early melanoma development by regulating important melanoma-related pathways and molecules. The latest developments in MIA research are summarized in this review, which describes recently published data related to the MIA protein structure and function, the role of MIA in melanoma development and progression, and the regulation of MIA expression. Furthermore, newly discovered MIA-homologous genes are discussed.
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53
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Deng J, Hua K, Caveney EJ, Takahashi N, Harp JB. Protein inhibitor of activated STAT3 inhibits adipogenic gene expression. Biochem Biophys Res Commun 2006; 339:923-31. [PMID: 16329991 DOI: 10.1016/j.bbrc.2005.10.217] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 10/30/2005] [Indexed: 10/25/2022]
Abstract
Protein inhibitor of activated STAT3 (PIAS3), a cytokine-induced repressor of signal transducer and activator of transcription 3 (STAT3) and a modulator of a broad array of nuclear proteins, is expressed in white adipose tissue, but its role in adipogenesis is not known. Here, we determined that PIAS3 was constitutively expressed in 3T3-L1 cells at all stages of adipogenesis. However, it translocated from the nucleus to the cytoplasm 4 days after induction of differentiation by isobutylmethylxanthine, dexamethasone, and insulin (MDI). In ob/ob mice, PIAS3 expression was increased in white adipose tissue depots compared to lean mice and was found in the cytoplasm of adipocytes. Overexpression of PIAS3 in differentiating preadipocytes, which localized primarily to the nucleus, inhibited mRNA level gene expression of adipogenic transcription factors C/EBPalpha and PPARgamma, as well as their downstream target genes aP2 and adiponectin. PIAS3 also inhibited C/EBPalpha promoter activation mediated specifically by insulin, but not dexamethasone or isobutylmethylxanthine. Taken together, these data suggest that PIAS3 may play an inhibitory role in adipogenesis by modulating insulin-activated transcriptional activation events. Increased PIAS3 expression in adipose tissue may play a role in the metabolic disturbances of obesity.
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Affiliation(s)
- Jianbei Deng
- Department of Nutrition, CB# 7461, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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54
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Levy C, Lee YN, Nechushtan H, Schueler-Furman O, Sonnenblick A, Hacohen S, Razin E. Identifying a common molecular mechanism for inhibition of MITF and STAT3 by PIAS3. Blood 2005; 107:2839-45. [PMID: 16368885 DOI: 10.1182/blood-2005-08-3325] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein inhibitor of activated STAT3 (PIAS3) functions in vivo as a key molecule in suppressing the transcriptional activity of both microphthalmia transcription factor (MITF) and signal transducer and activator of transcription 3 (STAT3), 2 transcription factors that play a major role in the regulation of growth and function in mast cells and melanocytes. Previously, we have demonstrated binding of PIAS3 to MITF leading to the inhibition of MITF transcriptional activity. Following cellular activation, PIAS3 is released from MITF and binds to STAT3. Now we have localized a common binding motif in PIAS3 for MITF and STAT3. This motif (PIAS82-132), which contains 50 amino acids, is sufficient for the inhibition of both MITF and STAT3. Three-dimensional protein modeling demonstrated that this motif contains 2 alpha helices. Disruption of one of the helices led to the loss of PIAS3 inhibitory activity. In addition to contributing to our understanding of the mechanisms of PIAS3 activity, these results could pave the way toward the formulation of an antioncogenic agent for the inhibition of both STAT3 and MITF.
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Affiliation(s)
- Carmit Levy
- Department of Biochemistry, Hebrew University Hadassah Medical School, POB 12272, Jerusalem 91120, Israel
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55
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Lee YN, Razin E. Nonconventional involvement of LysRS in the molecular mechanism of USF2 transcriptional activity in FcepsilonRI-activated mast cells. Mol Cell Biol 2005; 25:8904-12. [PMID: 16199869 PMCID: PMC1265770 DOI: 10.1128/mcb.25.20.8904-8912.2005] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reports of the biological multifunctional activity of various aminoacyl tRNA synthetases have recently accumulated in the literature. The primary function of these critical enzymes is to charge various tRNAs with their appropriate amino acids, thus producing the building blocks of protein synthesis. We have previously shown that lysyl tRNA synthetase (LysRS) associates with microphthalmia transcription factor (MITF) and regulates its activity by synthesis of Ap(4)A in mast cells. Here, we show for the first time that LysRS associates with another transcription factor, USF2, which unlike MITF, is ubiquitously expressed in eukaryotic cells. Using mast cells, we have found that USF2 is negatively regulated by Hint and Ap(4)A acts as a positive regulator of USF2 by a molecular mechanism similar to that described for MITF. Since USF2 plays a significant role in a variety of cellular functions, our finding suggests that LysRS and Ap(4)A may be involved in general regulation of gene transcription.
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Affiliation(s)
- Yu-Nee Lee
- Department of Biochemistry, Hebrew University Hadassah Medical School, Jerusalem, Israel
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56
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Sonnenblick A, Levy C, Razin E. Immunological trigger of mast cells by monomeric IgE: effect on microphthalmia transcription factor, STAT3 network of interactions. THE JOURNAL OF IMMUNOLOGY 2005; 175:1450-5. [PMID: 16034081 DOI: 10.4049/jimmunol.175.3.1450] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Microphthalmia transcription factor (MITF) and STAT3 are two transcription factors that play a major role in the regulation of growth and function of mast cells and melanocytes. We have previously provided experimental evidence regarding the functional cross-talk between MITF, protein inhibitor of activated STAT3, and STAT3 in response to cytokine activation of mast cells. Recent studies have demonstrated that binding of different IgE molecules to their FcepsilonRI induces a spectrum of intracellular events in the absence of specific Ag. In this work, we show for the first time that, in mouse bone marrow-derived mast cells and in rat basophilic leukemia cells, monomeric IgE alone can induce the MITF-protein inhibitor of activated STAT3-STAT3 network of interactions and leads to phosphorylation of MITF at S73 and of STAT3 at both tyrosine 705 and S727. This phosphorylation increases the transcriptional activity of MITF and STAT3 as indicated by mRNA accumulation of their target genes such as Bcl-2, granzyme B, and c-Myc. Interestingly, MITF and STAT3 were not found to be obligatory factors in the anti-apoptotic response induced by IgE. Thus, the phenomenon that IgE alone was able to induce transcription factors that are essential for mast cell function could contribute to our understanding of the pathogenesis of allergy and its associated diseases.
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Affiliation(s)
- Amir Sonnenblick
- Department of Biochemistry, Hebrew University Hadassah Medical School, Jerusalem, Israel
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57
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Shuai K, Liu B. Regulation of gene-activation pathways by PIAS proteins in the immune system. Nat Rev Immunol 2005; 5:593-605. [PMID: 16056253 DOI: 10.1038/nri1667] [Citation(s) in RCA: 313] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The protein inhibitor of activated STAT (PIAS) family of proteins has been proposed to regulate the activity of many transcription factors, including signal transducer and activator of transcription proteins (STATs), nuclear factor-kappaB, SMA- and MAD-related proteins (SMADs), and the tumour-suppressor protein p53. PIAS proteins regulate transcription through several mechanisms, including blocking the DNA-binding activity of transcription factors, recruiting transcriptional corepressors or co-activators, and promoting protein sumoylation. Recent genetic studies support an in vivo function for PIAS proteins in the regulation of innate immune responses. In this article, we review the current understanding of the molecular basis, specificity and physiological roles of PIAS proteins in the regulation of gene-activation pathways in the immune system.
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Affiliation(s)
- Ke Shuai
- Division of Hematology-Oncology, Department of Medicine, University of California, Los Angeles, California 90095, USA.
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58
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Tatzel J, Poser I, Schroeder J, Bosserhoff AK. Inhibition of melanoma inhibitory activity (MIA) expression in melanoma cells leads to molecular and phenotypic changes. ACTA ACUST UNITED AC 2005; 18:92-101. [PMID: 15760338 DOI: 10.1111/j.1600-0749.2005.00212.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The secreted protein melanoma inhibitory activity (MIA) is highly expressed in malignant melanoma but not in melanocytes and is associated with tumor progression in vivo. Here, we further investigated the functional role of MIA by inhibiting MIA expression of the human melanoma cell line HMB2 via stable antisense MIA cDNA transfection, and subsequent analysis of the cell clones. MIA-deficient cell clones showed several changes in cell morphology and growth pattern. In monolayer and three-dimensional culture enhanced cell-cell contacts were formed. Furthermore, a re-induction of pigment synthesis in comparison with the amelanotic parental cell line HMB2 was observed. Molecular analyses revealed a re-expression of tyrosinase-related protein 1 (Trp-1) and tyrosinase in the MIA-deficient cell clones necessary for melanin synthesis. In accordance, re-expression of MIA in the MIA-deficient melanoma cell clones resulted in downregulation of Trp-1. To identify the molecular mechanisms of MIA regulating pigmentation, MITF and PAX3, two positive regulators of Trp-1 and tyrosinase transcription, and PIAS3, a negative regulator of MITF activity, were analyzed. Only in MIA-deficient cells, expression of PAX3 mRNA and MITF protein was found. In contrast, strong expression of PIAS3 was detected in HMB2 but not in the MIA-deficient cells. To our knowledge this is the first report demonstrating a correlation between MIA expression and pigmentation and morphology of melanocytic cells.
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Affiliation(s)
- Jutta Tatzel
- Institute of Pathology, University of Regensburg, D-93053 Regensburg, Germany
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59
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Abstract
The first mouse microphthalmia transcription factor (Mitf ) mutation was discovered over 60 years ago, and since then over 24 spontaneous and induced mutations have been identified at the locus. Mitf encodes a member of the Myc supergene family of basic helix-loop-helix zipper (bHLH-Zip) transcription factors. Like Myc, Mitf regulates gene expression by binding to DNA as a homodimer or as a heterodimer with another related family member, in the case of Mitf the Tfe3, Tfeb, and Tfec proteins. The study of Mitf has provided many insights into the biology of melanocytes and helped to explain how melanocyte-specific gene expression and signaling is regulated. The human homologue of MITF is mutated in patients with the pigmentary and deafness disorder Waardenburg Syndrome Type 2A (WS2A). The mouse Mitf mutations therefore serve as a model for the study of this human disease. Mutations and/or aberrant expression of several MITF family member genes have also been reported in human cancer, including melanoma (MITF), papillary renal cell carcinoma (TFE3, TFEB), and alveolar soft part sarcoma (TFE3). Genes in the MITF/TFE pathway may therefore also represent valuable therapeutic targets for the treatment of human cancer. Here we review recent developments in the analysis of Mitf function in vivo and in vitro and show how traditional genetics, modern forward genetics and in vitro biochemical analyses have combined to produce an intriguing story on the role and actions of a gene family in a living organism.
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Affiliation(s)
- Eiríkur Steingrímsson
- Department of Biochemistry and Molecular Biology, University of Iceland, 101 Reykjavik, Iceland.
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60
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Abstract
The enormous variety of pigmentation phenotypes in nature reflects a series of remarkable events that begin in the neural crest and end with the manufacture and distribution of pigment by mature melanocytes located in the epidermis and hair follicles. While the origins of melanoblasts from multipotent precursors in the neural crest is striking in itself, yet more so is the fact that these pioneer melanoblasts manage to undertake and survive their long migration, and in doing so proliferate and maintain their identity before ultimately arriving at their destination and undergoing differentiation. With the application of the powerful combination of genetics and molecular and cell biology the mystery surrounding the genesis of the melanocyte lineage is slowly being unravelled. At its heart is the powerful alliance between signal transduction and transcription that coordinates the program of gene expression that confers on a cell its identity, provides its passport for migration, and instructs it in the arts of survival and timely reproduction. The realization that the proliferation and migration of melanoblasts during development resembles closely the proliferation and metastasis of melanoma, a highly dangerous and increasingly common cancer, serves to highlight the value of the melanocyte system as a model for addressing key issues of general significance in both development and cancer.
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Affiliation(s)
- Keith W Vance
- Signalling and Development Laboratory, Marie Curie Research Institute, The Chart, Oxted, Surrey, UK
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61
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Miller AJ, Levy C, Davis IJ, Razin E, Fisher DE. Sumoylation of MITF and Its Related Family Members TFE3 and TFEB. J Biol Chem 2005; 280:146-55. [PMID: 15507434 DOI: 10.1074/jbc.m411757200] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MITF and its related family members TFE3 and TFEB heterodimerize with each other, recognize the same DNA sequences, and are subject to many of the same post-translational modifications. We show that lysine residues within conserved small ubiquitin-like modifier (SUMO) consensus sites in these family members are subject to SUMO modification. Mutation of these sites significantly affects the transcriptional activity of MITF but does not alter dimerization, DNA binding, stability, or nuclear localization. Mutagenesis reducing the number of MITF binding sites in the promoter of TRPM1 from three to one eliminated the difference in transcriptional activity between the MITF mutants. Among other MITF target gene promoter constructs, differences in transcriptional activity between wild type and non-sumoylatable MITF were only seen in promoters with multiple MITF binding sites. These data support a synergy control model in which the functional consequences of MITF sumoylation depend on promoter context. Sumoylation, thus, provides a possible mechanism for altering the effects of MITF by affecting the target genes that it activates.
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Affiliation(s)
- Arlo J Miller
- Dana-Farber Cancer Institute and Children's Hospital, Department of Pediatric Hematology/Oncology, Melanoma Program in Medical Oncology, Harvard Medical School, Boston, Massachusetts 02115, USA
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62
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Sonnenblick A, Levy C, Razin E. Interplay between MITF, PIAS3, and STAT3 in mast cells and melanocytes. Mol Cell Biol 2004; 24:10584-92. [PMID: 15572665 PMCID: PMC533964 DOI: 10.1128/mcb.24.24.10584-10592.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Microphthalmia transcription factor (MITF) and STAT3 are two transcription factors that play a major role in the regulation of growth and function in mast cells and melanocytes. In the present study, we explored the MITF-PIAS3-STAT3 network of interactions, how these interactions regulate gene expression, and how cytokine-mediated phosphorylation of MITF and STAT3 is involved in the in vivo interplay between these three proteins. In NIH 3T3 cells stimulated via gp130 receptor, transfected MITF was found to be phosphorylated at S409. Such phosphorylation of MITF leads to PIAS3 dissociation from MITF and its association with STAT3. Activation of mouse melanoma and mast cells through gp130 or c-Kit receptors induced the mobilization of PIAS3 from MITF to STAT3. In mast cells derived from MITF(di/di) mice, whose MITF lacks the Zip domain (PIAS3-binding domain), we found downregulation in mRNA levels of genes regulated by either MITF or STAT3. This regulatory mechanism is of considerable importance since it is likely to advance the deciphering of a role for MITF and STAT3 in mast cells and melanocytes.
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MESH Headings
- Animals
- Blotting, Western
- Cells, Cultured
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/metabolism
- Down-Regulation
- Electrophoresis, Polyacrylamide Gel
- Fluorescent Dyes
- Glutathione Transferase/metabolism
- Intracellular Signaling Peptides and Proteins/chemistry
- Intracellular Signaling Peptides and Proteins/metabolism
- Mast Cells/metabolism
- Melanocytes/metabolism
- Melanoma, Experimental/pathology
- Mice
- Mice, Transgenic
- Microphthalmia-Associated Transcription Factor
- Microscopy, Fluorescence
- Models, Biological
- NIH 3T3 Cells
- Phosphorylation
- Precipitin Tests
- Protein Inhibitors of Activated STAT
- Protein Structure, Tertiary
- Proto-Oncogene Proteins c-kit/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cytokine/metabolism
- Recombinant Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Rhodamines
- Serine/metabolism
- Signal Transduction
- Transcription Factors/chemistry
- Transcription Factors/metabolism
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Affiliation(s)
- Amir Sonnenblick
- Department of Biochemistry, Hebrew University Hadassah Medical School, POB 12272, Jerusalem 91120, Israel
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63
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Jang HD, Yoon K, Shin YJ, Kim J, Lee SY. PIAS3 Suppresses NF-κB-mediated Transcription by Interacting with the p65/RelA Subunit. J Biol Chem 2004; 279:24873-80. [PMID: 15140884 DOI: 10.1074/jbc.m313018200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nuclear factor-kappaB (NF-kappaB) is a transcription factor critical for key cellular processes, including immune response, apoptosis, and cell cycle progression. A yeast two-hybrid screening, using the Rel homology domain (RHD) of the p65 subunit (RelA) of NF-kappaB as bait, led to the isolation of PIAS3, previously identified as a specific inhibitor of STAT3. We show that PIAS3 can directly associate with p65 using an in vitro pull-down and in vivo coimmunoprecipitation assays. When overexpressed, PIAS3 inhibits NF-kappaB-dependent transcription induced by treatment with tumor necrosis factor alpha (TNF-alpha) or interleukin-1beta or by overexpression of TNF family receptors such as RANK, TNFR1, and CD30 or signal transducers of TNF receptor-associated factors (TRAFs), including TRAF2, TRAF5, and TRAF6. Downregulation of PIAS3 by RNA interference reverses its effect on TNF-alpha-mediated NF-kappaB activation. We found that an N-terminal region of PIAS3 is necessary for both the interaction with p65 and the transcriptional suppression activity. In addition, we found that an LXXLL coregulator signature motif located within the N-terminal region of PIAS3 is the minimal requirement for the interaction with p65. Furthermore, we demonstrate that PIAS3 interferes with p65 binding to the CBP coactivator, thereby resulting in a decreased NF-kappaB-dependent transcription. Taken together, these data suggest that PIAS3 may function in vivo as a modulator in suppressing the transcriptional activity of p65.
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MESH Headings
- Amino Acid Motifs
- Animals
- Antigens, CD/metabolism
- Blotting, Western
- Carrier Proteins/metabolism
- Cell Cycle
- Cell Line
- Dose-Response Relationship, Drug
- Enzyme Activation
- Glutathione Transferase/metabolism
- Glycoproteins/metabolism
- Humans
- Interleukin-1/metabolism
- Ki-1 Antigen/metabolism
- Luciferases/metabolism
- NF-kappa B/metabolism
- NF-kappa B/physiology
- Osteoprotegerin
- Plasmids/metabolism
- Precipitin Tests
- Protein Binding
- Protein Structure, Tertiary
- Proteins/metabolism
- RNA Interference
- RNA, Small Interfering/metabolism
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor, Type I
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
- TNF Receptor-Associated Factor 5
- TNF Receptor-Associated Factor 6
- Time Factors
- Transcription Factor RelA
- Transcription, Genetic
- Transfection
- Tumor Necrosis Factor-alpha/metabolism
- Two-Hybrid System Techniques
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Affiliation(s)
- Hyun Duk Jang
- Division of Molecular Life Sciences and Center for Cell Signaling Research, Ewha Womans University, Seoul 120-750, Korea
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64
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Lee YN, Nechushtan H, Figov N, Razin E. The function of lysyl-tRNA synthetase and Ap4A as signaling regulators of MITF activity in FcepsilonRI-activated mast cells. Immunity 2004; 20:145-51. [PMID: 14975237 DOI: 10.1016/s1074-7613(04)00020-2] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Revised: 12/11/2003] [Accepted: 12/17/2003] [Indexed: 11/24/2022]
Abstract
The involvement of microphthalmia transcription factor (MITF) in the function of mast cells, melanocytes, and osteoclasts has recently started to be investigated in depth. In a previous study, we found Hint to be associated with MITF in mast cells and showed that it suppresses MITF's transcriptional activity. Here, we have found that lysyl-tRNA synthetase (LysRS) is also associated with MITF and forms a multicomplex with MITF and Hint. We have also shown that Ap4A, an endogenous molecule consisting of two adenosine linked by four phosphate which is known to be synthesized by LysRS, is accumulated intracellularily above 700 microM in IgE-Ag-activated mast cells, binds to Hint, liberates MITF, and thus leads to the activation of MITF-dependent gene expression. This implies that LysRS plays a key role via Ap4A as an important signaling molecule in MITF transcriptional activity.
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Affiliation(s)
- Yu-Nee Lee
- Department of Biochemistry, Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
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65
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Joo A, Aburatani H, Morii E, Iba H, Yoshimura A. STAT3 and MITF cooperatively induce cellular transformation through upregulation of c-fos expression. Oncogene 2004; 23:726-34. [PMID: 14737107 DOI: 10.1038/sj.onc.1207174] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The signal transducer and activator of transcription (STAT) family proteins are transcription factors critical in mediating cytokine signaling. Among them, STAT3 is frequently activated in a number of human cancers and transformed cell lines and is implicated in tumorigenesis. However, although constitutively activated STAT3 mutant (STAT3C) leads to cellular transformation, its transformation potential such as colony-forming activity in soft-agar is much weaker than that of v-src. To identify tumorigenic factors that cooperatively induce cellular transformation with STAT3C, we screened the retroviral cDNA library. We found that the microphthalmia-associated transcription factor (MITF), an essential transcription factor for melanocyte development and pigmentation, induces anchorage-independent growth of NIH-3T3 cells in cooperation with STAT3C. Microarray analysis revealed that c-fos is highly expressed in transformants expressing STAT3C and MITF. Promoter analysis and chromatin immunoprecipitation assay suggested that both STAT3 and MITF can cooperatively upregulate the c-fos gene. In addition, the transformation of NIH-3T3 cells by both MITF and STAT3C was significantly suppressed by a dominant-negative AP-1 retrovirus. These data indicate that MITF and STAT3 cooperatively induce c-fos, resulting in cellular transformation.
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Affiliation(s)
- Akiko Joo
- Division of Molecular and Cellular Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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66
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Levy C, Sonnenblick A, Razin E. Role played by microphthalmia transcription factor phosphorylation and its Zip domain in its transcriptional inhibition by PIAS3. Mol Cell Biol 2004; 23:9073-80. [PMID: 14645519 PMCID: PMC309632 DOI: 10.1128/mcb.23.24.9073-9080.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutation of microphthalmia transcription factor (MITF) results in deafness, bone loss, small eyes, and poorly pigmented eyes and skin. A search for MITF-associated proteins, using a mast cell library that was screened with a construct that encodes the basic helix-loop-helix leucine zipper (Zip) domain of MITF, resulted in the isolation of the STAT3 inhibitor, PIAS3. PIAS3 functions in vivo as a key molecule in suppressing the transcriptional activity of MITF. Here, we report that the Zip domain is the region of MITF that is involved in the direct interaction between MITF and PIAS3. Additionally, we investigated the effect of phosphorylation of MITF on its interaction with PIAS3. We found that phosphorylation of MITF on serines in positions 73 and 409 plays an important role in its association with PIAS3. This effect was profound with phosphorylation on Ser409, which significantly reduced the inhibitory effect of PIAS3 on MITF and also modulated the transcriptional activity of MITF. Thus, phosphorylation of MITF could be considered a fine, and alternative, tuning of its transcriptional machinery.
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Affiliation(s)
- Carmit Levy
- Department of Biochemistry, Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
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67
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Long J, Wang G, Matsuura I, He D, Liu F. Activation of Smad transcriptional activity by protein inhibitor of activated STAT3 (PIAS3). Proc Natl Acad Sci U S A 2004; 101:99-104. [PMID: 14691252 PMCID: PMC314145 DOI: 10.1073/pnas.0307598100] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Indexed: 01/22/2023] Open
Abstract
Smad proteins play pivotal roles in mediating the transforming growth factor beta (TGF-beta) transcriptional responses. We show in this report that PIAS3, a member of the protein inhibitor of activated STAT (PIAS) family, activates TGF-beta/Smad transcriptional responses. PIAS3 interacts with Smad proteins, most strongly with Smad3. PIAS3 and Smad3 interact with each other at the endogenous protein level in mammalian cells and also in vitro, and the association occurs through the C-terminal domain of Smad3. We further show that PIAS3 can interact with the general coactivators p300/CBP, the first evidence that a PIAS protein can associate with p300/CBP. In contrast, PIASy, which inhibits Smad transcriptional activity and other transcriptional responses, is unable to interact with p300/CBP. The RING domain of PIAS3 is essential for interaction with p300/CBP, and a RING domain mutant PIAS3, which cannot bind p300/CBP, no longer activates TGF-beta/Smad-dependent transcription. Furthermore, we show that PIAS3, Smad3, and p300 can form a ternary complex, which is markedly increased by TGF-beta treatment. Taken together, our studies indicate that on TGF-beta treatment, PIAS3 can form a complex with Smads and p300/CBP and activate Smad transcriptional activity.
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Affiliation(s)
- Jianyin Long
- Center for Advanced Biotechnology and Medicine, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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Nojiri S, Joh T, Miura Y, Sakata N, Nomura T, Nakao H, Sobue S, Ohara H, Asai K, Ito M. ATBF1 enhances the suppression of STAT3 signaling by interaction with PIAS3. Biochem Biophys Res Commun 2004; 314:97-103. [PMID: 14715251 DOI: 10.1016/j.bbrc.2003.12.054] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
ATBF1 was first discovered as a suppressor of AFP expression in hepatocytes. It is present in brain, adult liver, lung, and gastro-intestinal tract. Recently, it has been reported that ATBF1 regulates myoblastic differentiation and interacts with v-Myb in regulation of its transactivation. Using the yeast two-hybrid system, we searched for protein-protein interactions to uncover new functions for ATBF1. We present here experimental evidence that ATBF1 is a new regulatory factor for STAT3-mediated signal transduction through its interaction with PIAS3. PIAS3 was thus identified as an ATBF1-binding protein. In co-transfection experiments, the full-length ATBF1 was found to form complexes with PIAS3 in Hep G2 cells. In the luciferase assay, ATBF1 was found to have no influence on STAT3 signaling induced by IL-6 stimulation, but it did synergistically enhance PIAS3 inhibition of activated STAT3. In conclusion, ATBF1 can suppress the IL-6-mediated cellular response by acting together with PIAS3.
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Affiliation(s)
- Shunsuke Nojiri
- Department of Internal Medicine and Bioregulation, Nagoya City University Graduate School of Medical Sciences 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Japan
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Duval D, Duval G, Kedinger C, Poch O, Boeuf H. The 'PINIT' motif, of a newly identified conserved domain of the PIAS protein family, is essential for nuclear retention of PIAS3L. FEBS Lett 2003; 554:111-8. [PMID: 14596924 DOI: 10.1016/s0014-5793(03)01116-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PIAS proteins, cytokine-dependent STAT-associated repressors, exhibit intrinsic E3-type SUMO ligase activities and form a family of transcriptional modulators. Three conserved domains have been identified so far in this protein family, the SAP box, the MIZ-Zn finger/RING module and the acidic C-terminal domain, which are essential for protein interactions, DNA binding or SUMO ligase activity. We have identified a novel conserved domain of 180 residues in PIAS proteins and shown that its 'PINIT' motif as well as other conserved motifs (in the SAP box and in the RING domain) are independently involved in nuclear retention of PIAS3L, the long form of PIAS3, that we have characterized in mouse embryonic stem cells.
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Affiliation(s)
- D Duval
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, P.O. Box 10142, C.U. de Strasbourg, 67404 Illkirch, France
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Chiellini C, Costa M, Novelli SE, Amri EZ, Benzi L, Bertacca A, Cohen P, Del Prato S, Friedman JM, Maffei M. Identification of cathepsin K as a novel marker of adiposity in white adipose tissue. J Cell Physiol 2003; 195:309-21. [PMID: 12652657 DOI: 10.1002/jcp.10253] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In obesity, adipocytes undergo dramatic morphological and molecular changes associated with alterations in their gene expression profile. To identify genes differentially modulated in white adipose tissue (WAT) of obese db/db mice compared to wild type (wt) mice, we utilized RNA fingerprinting. Among the 52 candidates that we identified, we focused here on cathepsin K (ctsk), a cysteine protease, prevalently localized in lysosomes and involved in bone extracellular matrix degradation. In db/db mice, WAT ctsk mRNA was elevated 5.9-fold, as were Mitf and TFE3 (2- and 3.3-fold respectively), two transcription factors involved in ctsk induction in osteoclasts. Moreover, the level of WAT ctsk mRNA was increased in other obese models including A(y), fat, and tubby (2.8-, 3.2-, and 4.9-fold respectively) and decreased in mice undergoing weight loss. Despite the ubiquitous distribution of the ctsk transcript, we demonstrated that the obesity related increase is specific to the adipocytes. Further, in vitro experiments proved that the abundance of ctsk transcript increases upon adipose conversion of the established cell line of preadipocytes 3T3-F442A. In addition, ctsk gene expression was examined in adipose tissue of 21 lean and obese male subjects and significant correlations with BMI (r = 0.54, P = 0.012) and plasma leptin levels (r = 0.54, P = 0.015) were found. In conclusion, the WAT of obese db/db mice exhibits a different expression profile from that of the wt mice, and cathepsin K can be considered a novel marker of obesity and a target for the inhibition of adipose mass growth.
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Affiliation(s)
- Chiara Chiellini
- Department of Endocrinology and Metabolism, University of Pisa, Ospedale di Cisanello, Pisa, Italy
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Abstract
Interferon regulatory factor-1 (IRF-1) is a transcriptional activator that is involved in interferon response, regulation of cell growth and oncogenesis. To try to identify the molecules that regulate the function of IRF-1, we performed yeast two-hybrid screening and isolated protein inhibitor of activated STAT3 (PIAS3) as an IRF-1-binding protein. This protein was also found to bind with small ubiquitin-related modifier-1 (SUMO-1) and ubiquitin-conjugating enzyme 9, an E2 in the SUMO-1-conjugating system. Co-expression of PIAS3 induced SUMO-1 modification of IRF-1 in a RING finger domain-dependent manner and also repressed transcriptional activity of IRF-1. Thus, PIAS3 functions as a SUMO-1 ligase for IRF-1 and also as a repressor of IRF-1 transcriptional activity.
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Affiliation(s)
- Koji Nakagawa
- Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
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Abstract
Mutation of microphthalmia transcription factor (MITF) results in deafness, bone loss, small eyes, and poorly pigmented eyes and skin. The primary cell types affected in MITF-deficient mice are melanocytes, osteoclasts and mast cells. A search for MITF-associated proteins, using a mast cell library that was screened with a construct that encodes the basic helix-loop-helix leucine zipper (bHLH-Zip) domain of MITF, resulted in the isolation of the protein kinase C interacting (PKCI) protein 1 and protein inhibitor of activated STAT3 (PIAS3). We have accumulated clear evidence of a function for these two proteins as repressors of MITF-induced transcriptional activity. Here, we describe this evidence and ideas that give some insight into the cellular network of interactions between various transcription factors and MITF.
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Affiliation(s)
- Hovav Nechushtan
- Department of Biochemistry, Hebrew University-Hadassah Medical School, P.O. Box 12272, 91120, Jerusalem, Israel
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