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He DX, Li GH, Gu XT, Zhang L, Mao AQ, Wei J, Liu DQ, Shi GY, Ma X. A new agent developed by biotransformation of polyphyllin VII inhibits chemoresistance in breast cancer. Oncotarget 2017; 7:31814-24. [PMID: 26701723 PMCID: PMC5077978 DOI: 10.18632/oncotarget.6674] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/05/2015] [Indexed: 11/25/2022] Open
Abstract
Biotransformation by the endophytes of certain plants changes various compounds, and this ‘green’ chemistry becomes increasingly important for finding new products with pharmacological activity. In this study, polyphyllin VII (PPL7) was biotransformed by endophytes from the medicinal plant Paris polyphylla Smith, var. yunnanensis. This produced a new compound, ZH-2, with pharmacological activity in vitro and in vivo. ZH-2 was more potent than PPL7 in selectively killing more chemoresistant than chemosensitive breast cancer cells. ZH-2 also re-sensitized chemoresistant breast cancer cells, as evidenced by the improved anti-cancer activity of commonly-used chemotherapeutic agent in vitro, in vivo, and in clinical samples. This anti-chemoresistance effect of ZH-2 was associated with inhibiting the epithelial-mesenchymal transition (EMT) pathway. Taken together, our findings are the first one to link biotransformation with a biomedicine. The results provide insights into developing new pharmacologically-active agents via biotransformation by endophytes.
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Affiliation(s)
- Dong-Xu He
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Guo-Hong Li
- Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of The Ministry of Education, Yunnan University, Kunming 650091, China
| | - Xiao-Ting Gu
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Liang Zhang
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Ai-Qin Mao
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Juan Wei
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - De-Quan Liu
- Department of Breast Surgery, The Third Affiliated Hospital, Kunming Medical University, Kunming 650031, China
| | - Gui-Yang Shi
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
| | - Xin Ma
- School of Pharmaceutical Sciences National Engineering, and Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China
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TGF-β signaling in stem cells and tumorigenesis. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
INTRODUCTION The transforming growth factor-β (TGF-β) signaling pathway has a pivotal role in tumor suppression and yet, paradoxically, in tumor promotion. Functional context dependent insights into the TGF-β pathway are crucial in developing TGF-β-based therapeutics for cancer. AREAS COVERED This review discusses the molecular mechanism of the TGF-β pathway and describes the different ways of tumor suppression by TGF-β. It is then explained how tumors can evade these effects and how TGF-β contributes to further growing and spreading of some of the tumors. In the last part of the review, the data on targeting TGF-β pathway for cancer treatment is assessed. This review focuses on anti-TGF-β based treatment and other options targeting activated pathways in tumors where the TGF-β tumor suppressor pathway is lost. Pre-clinical as well up to date results of the most recent clinical trials are given. EXPERT OPINION Targeting the TGF-β pathway can be a promising direction in cancer treatment. However, several challenges still exist, the most important are differentiating between the carcinogenic effects of TGF-β and its other physiological roles, and delineating the tumor suppressive versus the tumor promoting roles of TGF-β in each specific tumor. Future studies are needed in order to find safer and more effective TGF-β-based drugs.
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Affiliation(s)
- Lior H Katz
- Visiting Scientist, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Houston, TX, USA
| | - Ying Li
- Assistant Professor (Research), The University of Texas, M. D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Dr. Lopa Mishra’s Lab, Houston, TX, USA
| | - Jiun-Sheng Chen
- Research Assistant II, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Dr. Lopa Mishra’s Lab, Houston, TX, USA
| | - Nina M Muñoz
- Research Scientist, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Dr. Lopa Mishra’s Lab, Houston, TX, USA
| | - Avijit Majumdar
- Postdoctoral Fellow, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Dr.Lopa Mishra’s Lab, Houston, TX, USA
| | - Jian Chen
- Instructor, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Houston, TX, USA
| | - Lopa Mishra
- Del and Dennis McCarthy Distinguished Professor and Chair, The University of Texas, M.D. Anderson Cancer Center, Department of Gastroenterology, Hepatology, & Nutrition, Houston, TX, USA, Tel: +1 713 794 3221; Fax: +1 713 745 1886
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Eapen A, Kulkarni R, Ravindran S, Ramachandran A, Sundivakkam P, Tiruppathi C, George A. Dentin phosphophoryn activates Smad protein signaling through Ca2+-calmodulin-dependent protein kinase II in undifferentiated mesenchymal cells. J Biol Chem 2013; 288:8585-8595. [PMID: 23362283 DOI: 10.1074/jbc.m112.413997] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dentin phosphophoryn (DPP) is a major noncollagenous protein in the dentin matrix. In this study, we demonstrate that pluripotent stem cells such as C3H10T1/2 and human bone marrow cells can be committed to the osteogenic lineage by DPP. Treatment with DPP can stimulate the release of intracellular Ca(2+). This calcium flux triggered the activation of Ca(2+)-calmodulin-dependent protein kinase II (CaMKII). Activated CaMKII induced the phosphorylation of Smad1 and promoted nuclear translocation of p-Smad1. Inhibition of store Ca(2+) depletion by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) or down-regulation of CaMKII by KN-62, a selective cell-permeable pharmacological inhibitor or a dominant negative plasmid of CaMKII, blocked DPP-mediated Smad1 phosphorylation. Activation of Smad1 resulted in the expression of osteogenic markers such as Runx2, Osterix, DMP1, Bone sialoprotein, Osteocalcin, NFATc1, and Schnurri-2, which have been implicated in osteoblast differentiation. These findings suggest that DPP is capable of triggering commitment of pluripotent stem cells to the osteogenic lineage.
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Affiliation(s)
- Asha Eapen
- Department of Oral Biology, University of Illinois, Chicago, Illinois 60612
| | - Roma Kulkarni
- Department of Oral Biology, University of Illinois, Chicago, Illinois 60612
| | - Sriram Ravindran
- Department of Oral Biology, University of Illinois, Chicago, Illinois 60612
| | | | | | | | - Anne George
- Department of Oral Biology, University of Illinois, Chicago, Illinois 60612.
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Zhu Y, Colak T, Shenoy M, Liu L, Mehta K, Pai R, Zou B, Xie XS, Pasricha PJ. Transforming growth factor beta induces sensory neuronal hyperexcitability, and contributes to pancreatic pain and hyperalgesia in rats with chronic pancreatitis. Mol Pain 2012; 8:65. [PMID: 22963239 PMCID: PMC3515355 DOI: 10.1186/1744-8069-8-65] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 09/07/2012] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Transforming growth factor beta (TGFβ) is upregulated in chronic inflammation, where it plays a key role in wound healing and promoting fibrosis. However, little is known about the peripheral effects of TGFβ on nociception. METHODS We tested the in vitro effects of TGFβ1 on the excitability of dorsal root ganglia (DRG) neurons and the function of potassium (K) channels. We also studied the effects of TGFβ1 infusion on pain responses to noxious electrical stimulation in healthy rats as well as the effects of neutralization of TGFβ1 on evoked pain behaviors in a rat model of chronic pancreatitis. RESULTS Exposure to TGFβ1 in vitro increased sensory neuronal excitability, decreased voltage-gated A-type K(+) currents (IA) and downregulated expression of the Kv1.4 (KCNA4) gene. Further TGFβ1 infusion into the naïve rat pancreas in vivo induces hyperalgesia and conversely, neutralization of TGFβ1 attenuates hyperalgesia only in rats with experimental chronic pancreatitis. Paradoxically, TGFβ1 neutralization in naïve rats results in pancreatic hyperalgesia. CONCLUSIONS TGFβ1 is an important and complex modulator of sensory neuronal function in chronic inflammation, providing a link between fibrosis and nociception and is a potentially novel target for the treatment of persistent pain associated with chronic pancreatitis.
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Affiliation(s)
- Yaohui Zhu
- Johns Hopkins Center for Neurogastroenterology, Department of Medicine, Division of Gastroenterology and Hepatology, Baltimore, MD 21205, USA
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Possible Involvement of Smad Signaling Pathways in Induction of Odontoblastic Properties in KN-3 Cells by Bone Morphogenetic Protein-2: A Growth Factor to Induce Dentin Regeneration. Int J Dent 2012; 2012:258469. [PMID: 22505896 PMCID: PMC3299296 DOI: 10.1155/2012/258469] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 12/12/2011] [Indexed: 11/18/2022] Open
Abstract
We examined the effects of bone morphogenetic protein-2 (BMP-2) on growth, differentiation, and intracellular signaling pathways of odontoblast-like cells, KN-3 cells, to clarify molecular mechanisms of odontoblast differentiation during pulp regeneration process. After treatment with BMP-2, the cell morphology, growth, alkaline phosphatase (ALP) activity, and the activation and expression of BMP-induced intracellular signaling molecules, such as Smad1/5/8 and Smad6/7, as well as activities of dentin sialoprotein (DSP) and dentin matrix protein 1 (DMP1), were examined. BMP-2 had no effects on the morphology, growth, or ALP activity of KN-3 cells, whereas it induced the phosphorylation of Smad1/5/8 and expression of Smad6/7. BMP-2 also induced the expressions of DSP and DMP-1. Our results suggest that KN-3 cells may express an odontoblastic phenotype with the addition of BMP-2 through the activation of Smad signaling pathways.
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Pinidiyaarachchi A, Zieba A, Allalou A, Pardali K, Wählby C. A detailed analysis of 3D subcellular signal localization. Cytometry A 2009; 75:319-28. [PMID: 19006073 DOI: 10.1002/cyto.a.20663] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Detection and localization of fluorescent signals in relation to other subcellular structures is an important task in various biological studies. Many methods for analysis of fluorescence microscopy image data are limited to 2D. As cells are in fact 3D structures, there is a growing need for robust methods for analysis of 3D data. This article presents an approach for detecting point-like fluorescent signals and analyzing their subnuclear position. Cell nuclei are delineated using marker-controlled (seeded) 3D watershed segmentation. User-defined object and background seeds are given as input, and gradient information defines merging and splitting criteria. Point-like signals are detected using a modified stable wave detector and localized in relation to the nuclear membrane using distance shells. The method was applied to a set of biological data studying the localization of Smad2-Smad4 protein complexes in relation to the nuclear membrane. Smad complexes appear as early as 1 min after stimulation while the highest signal concentration is observed 45 min after stimulation, followed by a concentration decrease. The robust 3D signal detection and concentration measures obtained using the proposed method agree with previous observations while also revealing new information regarding the complex formation.
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Bobbili N, Kim Y, Dunn M, Yang J, Ong A. Effects of maternal immunisation against myostatin on post-natal growth and skeletal muscle mass of offspring in mice. FOOD AGR IMMUNOL 2008. [DOI: 10.1080/09540100801956596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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9
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Modulation of the Bioactive Conformation of Transforming Growth Factor β: Possible Implications of Cation Binding for Biological Function. Top Curr Chem (Cham) 2008. [DOI: 10.1007/128_2007_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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10
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Abstract
Transforming growth factor-beta (TGF-beta) represents a large family of growth and differentiation factors that mobilize complex signaling networks to regulate cellular differentiation, proliferation, motility, adhesion, and apoptosis. TGF-beta signaling is tightly regulated by multiple complex mechanisms, and its deregulation plays a key role in the progression of many forms of cancer. Upon ligand binding, TGF-beta signals are transduced by Smad proteins, which in turn are tightly dependent on modulation by adaptor proteins such as embryonic liver fodrin, Smad anchor for receptor activation, filamin, and crkl. A further layer of regulation is imposed by ubiquitin-mediated targeting and proteasomal degradation of specific components of the TGF-beta signaling pathway. This review focuses on the ubiquitinators that regulate TGF-beta signaling and the association of these ubiquitin ligases with various forms of cancer. Delineating the role of ubiquitinators in the TGF-beta signaling pathway could yield powerful novel therapeutic targets for designing new cancer treatments.
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Affiliation(s)
- Eric Glasgow
- Laboratory of Cancer Genetics, Digestive Diseases, and GI Developmental Biology, Department of Surgery, Medicine and Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007, USA.
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Kraich M, Klein M, Patiño E, Harrer H, Nickel J, Sebald W, Mueller TD. A modular interface of IL-4 allows for scalable affinity without affecting specificity for the IL-4 receptor. BMC Biol 2006; 4:13. [PMID: 16640778 PMCID: PMC1479839 DOI: 10.1186/1741-7007-4-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Accepted: 04/26/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Interleukin 4 (IL-4) is a key regulator of the immune system and an important factor in the development of allergic hypersensitivity. Together with interleukin 13 (IL-13), IL-4 plays an important role in exacerbating allergic and asthmatic symptoms. For signal transduction, both cytokines can utilise the same receptor, consisting of the IL-4Ralpha and the IL-13Ralpha1 chain, offering an explanation for their overlapping biological functions. Since both cytokine ligands share only moderate similarity on the amino acid sequence level, molecular recognition of the ligands by both receptor subunits is of great interest. IL-4 and IL-13 are interesting targets for allergy and asthma therapies. Knowledge of the binding mechanism will be important for the generation of either IL-4 or IL-13 specific drugs. RESULTS We present a structure/function analysis of the IL-4 ligand-receptor interaction. Structural determination of a number of IL-4 variants together with in vitro binding studies show that IL-4 and its high-affinity receptor subunit IL-4Ralpha interact via a modular protein-protein interface consisting of three independently-acting interaction clusters. For high-affinity binding of wild-type IL-4 to its receptor IL-4Ralpha, only two of these clusters (i.e. cluster 1 centered around Glu9 and cluster 2 around Arg88) contribute significantly to the free binding energy. Mutating residues Thr13 or Phe82 located in cluster 3 to aspartate results in super-agonistic IL-4 variants. All three clusters are fully engaged in these variants, generating a three-fold higher binding affinity for IL-4Ralpha. Mutagenesis studies reveal that IL-13 utilizes the same main binding determinants, i.e. Glu11 (cluster 1) and Arg64 (cluster 2), suggesting that IL-13 also uses this modular protein interface architecture. CONCLUSION The modular architecture of the IL-4-IL-4Ralpha interface suggests a possible mechanism by which proteins might be able to generate binding affinity and specificity independently. So far, affinity and specificity are often considered to co-vary, i.e. high specificity requires high affinity and vice versa. Although the binding affinities of IL-4 and IL-13 to IL-4Ralpha differ by a factor of more than 1000, the specificity remains high because the receptor subunit IL-4Ralpha binds exclusively to IL-4 and IL-13. An interface formed by several interaction clusters/binding hot-spots allows for a broad range of affinities by selecting how many of these interaction clusters will contribute to the overall binding free energy. Understanding how proteins generate affinity and specificity is essential as more and more growth factor receptor families show promiscuous binding to their respective ligands. This limited specificity is, however, not accompanied by low binding affinities.
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Affiliation(s)
- Michael Kraich
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Markus Klein
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Edwin Patiño
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Henning Harrer
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Joachim Nickel
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Walter Sebald
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Rudolf-Virchow Zentrum, DFG Forschungszentrum für Experimentelle Biomedizin, Versbacher Str. 9, D-97078 Würzburg, Germany
| | - Thomas D Mueller
- Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Saha T, Vardhini D, Tang Y, Katuri V, Jogunoori W, Volpe EA, Haines D, Sidawy A, Zhou X, Gallicano I, Schlegel R, Mishra B, Mishra L. RING finger-dependent ubiquitination by PRAJA is dependent on TGF-beta and potentially defines the functional status of the tumor suppressor ELF. Oncogene 2006; 25:693-705. [PMID: 16247473 DOI: 10.1038/sj.onc.1209123] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In gastrointestinal cells, biological signals for transforming growth factor-beta (TGF-beta) are transduced through transmembrane serine/threonine kinase receptors that signal to Smad proteins. Smad4, a tumor suppressor, is often mutated in human gastrointestinal cancers. The mechanism of Smad4 inactivation, however, remains uncertain and could be through E3-mediated ubiquitination of Smad4/adaptor protein complexes. Disruption of ELF (embryonic liver fodrin), a Smad4 adaptor protein, modulates TGF-beta signaling. We have found that PRAJA, a RING-H2 protein, interacts with ELF in a TGF-beta-dependent manner, with a fivefold increase of PRAJA expression and a subsequent decrease in ELF and Smad4 expression, in gastrointestinal cancer cell lines (P < 0.05). Strikingly, PRAJA manifests substantial E3-dependent ubiquitination of ELF and Smad3, but not Smad4. Delta-PRAJA, which has a deleted RING finger domain at the C terminus, abolishes ubiquitination of ELF. A stable cell line that overexpresses PRAJA exhibits low levels of ELF in comparison to a Delta-PRAJA stable cell line, where ELF expression is high compared to normal controls. The alteration of ELF and/or Smad4 expression and/or function in the TGF-beta signaling pathway may be induced by enhancement of ELF degradation, which is mediated by a high-level expression of PRAJA in gastrointestinal cancers. In hepatocytes, half-life (t(1/2)) and rate constant for degradation (k(D)) of ELF is 1.91 h and 21.72 min(-1) when coupled with ectopic expression of PRAJA in cells stimulated by TGF-beta, compared to PRAJA-transfected unstimulated cells (t(1/2) = 4.33 h and k(D) = 9.6 min(-1)). These studies reveal a mechanism for tumorigenesis whereby defects in adaptor proteins for Smads, such as ELF, can undergo degradation by PRAJA, through the ubiquitin-mediated pathway.
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Affiliation(s)
- T Saha
- Department of Surgical Sciences, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007, USA
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Jadlowiec JA, Zhang X, Li J, Campbell PG, Sfeir C. Extracellular matrix-mediated signaling by dentin phosphophoryn involves activation of the Smad pathway independent of bone morphogenetic protein. J Biol Chem 2005; 281:5341-7. [PMID: 16326713 DOI: 10.1074/jbc.m506158200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells have ingenious mechanisms for interpreting complex signals from their external microenvironment. Previously, we have shown that phosphophoryn (PP) regulates the expression of bone/dentin marker genes via the integrin/MAPK signaling pathway (Jadlowiec, J., Koch, H., Zhang, X., Campbell, P. G., Seyedain, M., and Sfeir, C. (2004) J. Biol. Chem. 279, 53323-53330). We hypothesize that other signaling pathways important for mineralized tissue morphogenesis such as the Smad pathway could be involved in PP signaling. We determined activation of the Smad pathway in human adult mesenchymal stem cells following treatment with recombinant PP (rPP). We observed that PP enhanced phosphorylation of Smad1 within 30 min and Smad1 translocation to the nucleus within 1 h. PP up-regulated the expression of Smad1 target genes, Smad6, Dlx5, and Runx2. The timing of PP activation of Smad1 implies this is a direct effect; however, we also investigated the possible involvement of bone morphogenetic proteins in PP stimulation of the Smad pathway. PP was shown to up-regulate Bmp-2 gene expression 12 h post-treatment with PP, which is much later than initial detection of Smad1 phosphorylation at 30 min. Furthermore, addition of Noggin did not block Smad1 phosphorylation by PP. We propose that PP could signal via the Smad pathway by either directly stimulating the phosphorylation of Smad1 via integrins or other mechanisms. These might include integrin/bone morphogenetic protein receptor interactions or involvement of PP with other growth factors leading to the modulation of intracellular signaling. It is noteworthy that a non-transforming growth factor-beta family member activates the Smad pathway. The role of PP in regulating the Smad pathway raises very interesting questions regarding the role of PP during bone and tooth development.
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Affiliation(s)
- Julie A Jadlowiec
- Department of Oral Medicine and Pathology, School of Dental Medicine, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15261, USA
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Dubrovska A, Kanamoto T, Lomnytska M, Heldin CH, Volodko N, Souchelnytskyi S. TGFbeta1/Smad3 counteracts BRCA1-dependent repair of DNA damage. Oncogene 2005; 24:2289-97. [PMID: 15735739 DOI: 10.1038/sj.onc.1208443] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Inactivation of the BRCA1 gene has been found to confer susceptibility to early-onset familial breast and ovarian cancers. BRCA1 regulates DNA repair, chromatin remodeling and affects gene transcription. Transforming growth factor-beta (TGFbeta) is a potent regulator of growth, apoptosis and invasiveness of tumor cells, including breast cancer cells. Here we show that Smad3 which is a component of the TGFbeta signaling pathway, forms a complex with BRCA1 in vitro and in vivo. The interaction is mediated by the MH1 domain of Smad3 and the C-terminal part of BRCA1. We observed a co-localization of Smad3 and BRCA1 in nuclear complexes. We also found that TGFbeta1/Smad3 counteracted BRCA1-dependent repair of DNA double-strand breaks in human breast epithelial cells, as evaluated by BRCA1 nuclear foci formation, single-cell gel electrophoresis and cell survival assays. Thus, TGFbeta1/Smad3 suppresses BRCA1-dependent DNA repair in response to a DNA damaging agent.
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Affiliation(s)
- Anna Dubrovska
- Ludwig Institute for Cancer Research, Box 595, Biomedical Center, SE-751 24 Uppsala, Sweden
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15
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Chen HB, Rud JG, Lin K, Xu L. Nuclear targeting of transforming growth factor-beta-activated Smad complexes. J Biol Chem 2005; 280:21329-36. [PMID: 15799969 DOI: 10.1074/jbc.m500362200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Upon stimulation by the transforming growth factor beta (TGF-beta), Smad2 and Smad3 are phosphorylated at their C termini and assemble into stable heteromeric complexes with Smad4. These complexes are the functional entities that translocate into the nucleus and regulate the expression of TGF-beta target genes. Here we report that the TGF-beta-activated phospho-Smad3/Smad4 complex utilizes an importin-independent mechanism for nuclear import and engages different nucleoporins for nuclear import compared with the monomeric Smad4. Within the heteromeric complex, phospho-Smad3 appears to dominate over Smad4 in the nuclear import process and guides the complex to its nuclear destination. We also demonstrate that the binding of phospho-Smad3 to Smad4 prevents Smad4 from interacting with the nuclear export receptor chromosome region maintenance 1. In this way, TGF-beta signaling suppresses nuclear export of Smad4 by chromosome region maintenance 1 and thereby targets Smad4 into the nucleus. Indeed tumorigenic mutations in Smad4 that affect its interaction with Smad2 or Smad3 impair nuclear accumulation of Smad4 in response to TGF-beta.
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Affiliation(s)
- Hong Bing Chen
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Sebald W, Nickel J, Zhang JL, Mueller TD. Molecular recognition in bone morphogenetic protein (BMP)/receptor interaction. Biol Chem 2004; 385:697-710. [PMID: 15449706 DOI: 10.1515/bc.2004.086] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractBone morphogenetic proteins (BMPs) and other members of the TGF-β superfamily are secreted signalling proteins determining the development, maintenance and regeneration of tissues and organs. These dimeric proteins bind, via multiple epitopes, two types of signalling receptor chains and numerous extracellular modulator proteins that stringently control their activity. Crystal structures of free ligands and of complexes with type I and type II receptor extracellular domains and with the modulator protein Noggin reveal structural epitopes that determine the affinity and specificity of the interactions. Modelling of a ternary complex BMP/(BMPR-IAEC)2/(ActR-IIEC)2suggests a mechanism of receptor activation that does not rely on direct contacts between extracellular domains of the receptors. Mutational and interaction analyses indicate that the large hydrophobic core of the interface of BMP-2 (wrist epitope) with the type I receptor does not provide a hydrophobic hot spot for binding. Instead, main chain amide and carbonyl groups that are completely buried in the contact region represent major binding determinants. The affinity between ligand and receptor chains is probably strongly increased by two-fold interactions of the dimeric ligand and receptor chains that exist as homodimers in the membrane (avidity effects). BMP muteins with disrupted epitopes for receptor chains or modulator proteins provide clues for drug design and development.
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Affiliation(s)
- Walter Sebald
- Physiologische Chemie II, Theodor-Boveri-Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, D-97074 Würzburg, Germany.
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Bender H, Wang Z, Schuster N, Krieglstein K. TIEG1 facilitates transforming growth factor-beta-mediated apoptosis in the oligodendroglial cell line OLI-neu. J Neurosci Res 2004; 75:344-52. [PMID: 14743447 DOI: 10.1002/jnr.10856] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transforming growth factor-beta (TGF-beta) plays an important role during the period of developmental cell death in the nervous system. Using the oligodendroglial precursor cell line OLI-neu, we have previously established an in vitro system to analyze TGF-beta-mediated cell death on the molecular level. We could show that the Krüppel-like Zn-finger transcription factor TIEG1 was up-regulated after TGF-beta stimulation of OLI-neu cells and mimicked TGF-beta effects in these cells; i.e., overexpression of TIEG1 in OLI-neu cells induced apoptosis as shown by apoptosis ELISA, DNA fragmentation, and caspases-3 activation. The apoptotic pathway seemed to be initiated by repressing the expression of the antiapoptotic protein Bcl-XL. In contrast, the reporter activity of a SMAD consensus promoter was induced, whereas the promoter activity of the inhibitory SMAD7 was reduced, suggesting that SMAD-dependent TGF-beta responses, such as TGF-beta-induced apoptosis, are enhanced in the presence of TIEG1.
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Affiliation(s)
- Herdis Bender
- Center of Anatomy, University of Goettingen, Goettingen, Germany
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Sebald W, Mueller TD. The interaction of BMP-7 and ActRII implicates a new mode of receptor assembly. Trends Biochem Sci 2003; 28:518-21. [PMID: 14559178 DOI: 10.1016/j.tibs.2003.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The recently described structure of bone morphogenetic protein 7 in complex with the extracellular domain of the activin type receptor II provides a new and important paradigm to add to the list of possible modes of receptor assembly. A new mode of a ligand-mediated cooperative receptor assembly without receptor-receptor contacts yields new and exciting insights into the molecular signal transduction mechanism in the transforming growth factor-beta superfamily.
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Affiliation(s)
- Walter Sebald
- Department of Physiological Chemistry II, Biocenter, University of Wuerzburg, Am Hubland, D-97074, Wuerzburg, Germany.
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Moustakas A, Heldin CH. From mono- to oligo-Smads: the heart of the matter in TGF-beta signal transduction. Genes Dev 2002; 16:1867-71. [PMID: 12154118 DOI: 10.1101/gad.1016802] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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