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Zheng P, Qi Y, Li X, Liu Y, Yao Y, Huang G. A capsule network-based method for identifying transcription factors. Front Microbiol 2022; 13:1048478. [PMID: 36560938 PMCID: PMC9763301 DOI: 10.3389/fmicb.2022.1048478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 10/26/2022] [Indexed: 12/12/2022] Open
Abstract
Transcription factors (TFs) are typical regulators for gene expression and play versatile roles in cellular processes. Since it is time-consuming, costly, and labor-intensive to detect it by using physical methods, it is desired to develop a computational method to detect TFs. Here, we presented a capsule network-based method for identifying TFs. This method is an end-to-end deep learning method, consisting mainly of an embedding layer, bidirectional long short-term memory (LSTM) layer, capsule network layer, and three fully connected layers. The presented method obtained an accuracy of 0.8820, being superior to the state-of-the-art methods. These empirical experiments showed that the inclusion of the capsule network promoted great performances and that the capsule network-based representation was superior to the property-based representation for distinguishing between TFs and non-TFs. We also implemented the presented method into a user-friendly web server, which is freely available at http://www.biolscience.cn/Capsule_TF/ for all scientific researchers.
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Affiliation(s)
- Peijie Zheng
- School of Electrical Engineering, Shaoyang University, Shaoyang, China
| | - Yue Qi
- School of Electrical Engineering, Shaoyang University, Shaoyang, China
| | - Xueyong Li
- School of Electrical Engineering, Shaoyang University, Shaoyang, China
| | - Yuewu Liu
- College of Information and Intelligence, Hunan Agricultural University, Changsha, China
| | - Yuhua Yao
- School of Mathematics and Statistics, Hainan Normal University, Haikou, China
| | - Guohua Huang
- School of Electrical Engineering, Shaoyang University, Shaoyang, China,*Correspondence: Guohua Huang,
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2
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The role of transcription factors in the acquisition of the four latest proposed hallmarks of cancer and corresponding enabling characteristics. Semin Cancer Biol 2022; 86:1203-1215. [PMID: 36244529 DOI: 10.1016/j.semcancer.2022.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 01/27/2023]
Abstract
With the recent description of the molecular and cellular characteristics that enable acquisition of both core and new hallmarks of cancer, the consequences of transcription factor dysregulation in the hallmarks scheme has become increasingly evident. Dysregulation or mutation of transcription factors has long been recognized in the development of cancer where alterations in these key regulatory molecules can result in aberrant gene expression and consequential blockade of normal cellular differentiation. Here, we provide an up-to-date review of involvement of dysregulated transcription factor networks with the most recently reported cancer hallmarks and enabling characteristic properties. We present some illustrative examples of the impact of dysregulated transcription factors, specifically focusing on the characteristics of phenotypic plasticity, non-mutational epigenetic reprogramming, polymorphic microbiomes, and senescence. We also discuss how new insights into transcription factor dysregulation in cancer is contributing to addressing current therapeutic challenges.
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3
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Luo J, Liu K, Yao Y, Sun Q, Zheng X, Zhu B, Zhang Q, Xu L, Shen Y, Ren B. DMBX1 promotes tumor proliferation and regulates cell cycle progression via repressing OTX2-mediated transcription of p21 in lung adenocarcinoma cell. Cancer Lett 2019; 453:45-56. [DOI: 10.1016/j.canlet.2019.03.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 12/17/2022]
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4
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Expression analysis of genes encoding double B-box zinc finger proteins in maize. Funct Integr Genomics 2017; 17:653-666. [PMID: 28480497 DOI: 10.1007/s10142-017-0562-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 03/16/2017] [Accepted: 04/24/2017] [Indexed: 10/24/2022]
Abstract
The B-box proteins play key roles in plant development. The double B-box (DBB) family is one of the subfamily of the B-box family, with two B-box domains and without a CCT domain. In this study, 12 maize double B-box genes (ZmDBBs) were identified through a genome-wide survey. Phylogenetic analysis of DBB proteins from maize, rice, Sorghum bicolor, Arabidopsis, and poplar classified them into five major clades. Gene duplication analysis indicated that segmental duplications made a large contribution to the expansion of ZmDBBs. Furthermore, a large number of cis-acting regulatory elements related to plant development, response to light and phytohormone were identified in the promoter regions of the ZmDBB genes. The expression patterns of the ZmDBB genes in various tissues and different developmental stages demonstrated that ZmDBBs might play essential roles in plant development, and some ZmDBB genes might have unique function in specific developmental stages. In addition, several ZmDBB genes showed diurnal expression pattern. The expression levels of some ZmDBB genes changed significantly under light/dark treatment conditions and phytohormone treatments, implying that they might participate in light signaling pathway and hormone signaling. Our results will provide new information to better understand the complexity of the DBB gene family in maize.
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5
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Zhang J, Le TD, Liu L, He J, Li J. A novel framework for inferring condition-specific TF and miRNA co-regulation of protein-protein interactions. Gene 2015; 577:55-64. [PMID: 26611531 DOI: 10.1016/j.gene.2015.11.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 10/16/2015] [Accepted: 11/17/2015] [Indexed: 12/11/2022]
Abstract
Recent studies have shown that transcription factors (TFs) and microRNAs (miRNAs), while independently regulate their downstream targets, collaborate with each other to regulate gene expression. However, their synergistic roles in protein-protein interactions (PPIs) remain mostly unknown. In this paper, we present a novel framework (called CoRePPI) for inferring TF and miRNA co-regulation of PPIs. Particularly, CoRePPI is aimed at discovering the co-regulation specific to a condition of interest, by using heterogeneous data, including miRNA and messenger RNA (mRNA) expression profiles, putative miRNA targets, TF targets and PPIs. CoRePPI firstly finds the network motifs indicating the co-regulation of PPIs by TFs and miRNAs in tumor and normal conditions separately. Then by identifying the differential motifs found in one condition but not in the other, it builds the networks consisting of TFs, miRNAs and their co-regulated PPIs specific to different conditions respectively. To validate CoRePPI, we apply it to the Pan-Cancer dataset which includes the expression profiles of 12 cancer types from TCGA. Through network topology analysis, we found that the tumor and normal CoRePPI networks are scale-free. Furthermore, the results of differential and intersected network analysis between the tumor and normal CoRePPI networks suggest that only a small fraction of the regulatory relationships between TFs and miRNAs are conserved in both conditions but they co-regulate different downstream PPIs in tumor and normal conditions; and in different conditions the majority of the regulatory relationships between TFs and miRNAs are different although they may regulate the same PPIs in their respective conditions. The CoRePPI sub-networks constructed for the three types of cancers (breast cancer, lung cancer and ovarian cancer) are all scale-free, and the intersection of these CoRePPI sub-networks can be utilized as the biomarker CoRePPI sub-network of the three types of cancers. The PPI enrichment analyses of the tumor and normal CoRePPI networks suggest that the co-regulating TFs and miRNAs are significantly associated with the specific biological processes, diseases and pathways. In addition, comparing with the two non-condition-specific approaches, the tumor CoRePPI network is found to have the most enriched cancer-related PPIs. Altogether, the results uncover the combined regulatory patterns of TFs and miRNAs on the PPIs, and may provide new insights for research in cancer-associated TFs and miRNAs.
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Affiliation(s)
- Junpeng Zhang
- School of Engineering, Dali University, Dali, Yunnan 671003, China.
| | - Thuc Duy Le
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Lin Liu
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Jianfeng He
- School of Information Engineering and Automation, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Jiuyong Li
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia.
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6
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Park S, Sung B, Jang EJ, Kim DH, Park CH, Choi YJ, Ha YM, Kim MK, Kim ND, Yu BP, Chung HY. Inhibitory action of salicylideneamino-2-thiophenol on NF-κB signaling cascade and cyclooxygenase-2 in HNE-treated endothelial cells. Arch Pharm Res 2013; 36:880-9. [DOI: 10.1007/s12272-013-0116-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/02/2013] [Indexed: 01/04/2023]
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7
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Lokmic Z, Musyoka J, Hewitson TD, Darby IA. Hypoxia and hypoxia signaling in tissue repair and fibrosis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 296:139-85. [PMID: 22559939 DOI: 10.1016/b978-0-12-394307-1.00003-5] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Following injury, vascular damage results in the loss of perfusion and consequent low oxygen tension (hypoxia) which may be exacerbated by a rapid influx of inflammatory and mesenchymal cells with high metabolic demands for oxygen. Changes in systemic and cellular oxygen concentrations induce tightly regulated response pathways that attempt to restore oxygen supply to cells and modulate cell function in hypoxic conditions. Most of these responses occur through the induction of the transcription factor hypoxia-inducible factor-1 (HIF-1) which regulates many processes needed for tissue repair during ischemia in the damaged tissue. HIF-1 transcriptionally upregulates expression of metabolic proteins (GLUT-1), adhesion proteins (integrins), soluble growth factors (TGF-β and VEGF), and extracellular matrix components (type I collagen and fibronectin), which enhance the repair process. For these reasons, HIF-1 is viewed as a positive regulator of wound healing and a potential regulator of organ repair and tissue fibrosis. Understanding the complex role of hypoxia in the loss of function in scarring tissues and biology of chronic wound, and organ repair will aid in the development of pharmaceutical agents that can redress the detrimental outcomes often seen in repair and scarring.
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Affiliation(s)
- Zerina Lokmic
- Department of Surgery, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
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8
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Jiang Y, Zeng B, Zhao H, Zhang M, Xie S, Lai J. Genome-wide transcription factor gene prediction and their expressional tissue-specificities in maize. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2012; 54:616-30. [PMID: 22862992 DOI: 10.1111/j.1744-7909.2012.01149.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Transcription factors (TFs) are important regulators of gene expression. To better understand TF-encoding genes in maize (Zea mays L.), a genome-wide TF prediction was performed using the updated B73 reference genome. A total of 2298 TF genes were identified, which can be classified into 56 families. The largest family, known as the MYB superfamily, comprises 322 MYB and MYB-related TF genes. The expression patterns of 2 014 (87.64%) TF genes were examined using RNA-seq data, which resulted in the identification of a subset of TFs that are specifically expressed in particular tissues (including root, shoot, leaf, ear, tassel and kernel). Similarly, 98 kernel-specific TF genes were further analyzed, and it was observed that 29 of the kernel-specific genes were preferentially expressed in the early kernel developmental stage, while 69 of the genes were expressed in the late kernel developmental stage. Identification of these TFs, particularly the tissue-specific ones, provides important information for the understanding of development and transcriptional regulation of maize.
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Affiliation(s)
- Yi Jiang
- State Key Laboratory of Agrobiotechnology and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
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9
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Wang W. Regulatory RNA-binding proteins in senescence. Ageing Res Rev 2012; 11:485-90. [PMID: 22414963 DOI: 10.1016/j.arr.2012.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/08/2012] [Accepted: 02/08/2012] [Indexed: 11/18/2022]
Abstract
The expression of senescence-associated genes, which governs the progression and the maintenance of senescence, is regulated at multiple levels. Apart from the transcriptional mechanisms that control cellular senescence, studies over the past decade have revealed that post-transcriptional gene regulation, especially through changes in mRNA turnover and translation, critically influences protein expression patterns in the senescent cell. Among the post-transcriptional regulatory factors, RNA-binding proteins (RBPs) are particularly influential in the establishment of senescence-associated protein profiles. In this review, I discuss the current knowledge of the role of RBPs in cellular senescence and the molecular mechanisms that regulate their function.
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Affiliation(s)
- Wengong Wang
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100191, PR China.
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10
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11
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Wheaton K, Muir J, Ma W, Benchimol S. BTG2 antagonizes Pin1 in response to mitogens and telomere disruption during replicative senescence. Aging Cell 2010; 9:747-60. [PMID: 20569234 DOI: 10.1111/j.1474-9726.2010.00601.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cellular senescence limits the replicative capacity of normal cells and acts as an intrinsic barrier that protects against the development of cancer. Telomere shortening-induced replicative senescence is dependent on the ATM-p53-p21 pathway but additional genes likely contribute to senescence. Here, we show that the p53-responsive gene BTG2 plays an essential role in replicative senescence. Similar to p53 and p21 depletion, BTG2 depletion in human fibroblasts leads to an extension of cellular lifespan, and ectopic BTG2 induces senescence independently of p53. The anti-proliferative function of BTG2 during senescence involves its stabilization in response to telomere dysfunction followed by serum-dependent binding and relocalization of the cell cycle regulator prolyl isomerase Pin1. Pin1 inhibition leads to senescence in late-passage cells, and ectopic Pin1 expression rescues cells from BTG2-induced senescence. The neutralization of Pin1 by BTG2 provides a critical mechanism to maintain senescent arrest in the presence of mitogenic signals in normal primary fibroblasts.
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Affiliation(s)
- Keith Wheaton
- Department of Biology, York University, Toronto, Ontario, Canada.
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12
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Mazzatti DJ, White A, Forsey RJ, Powell JR, Pawelec G. Gene expression changes in long-term culture of T-cell clones: genomic effects of chronic antigenic stress in aging and immunosenescence. Aging Cell 2007; 6:155-63. [PMID: 17286612 PMCID: PMC2049045 DOI: 10.1111/j.1474-9726.2007.00269.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The adaptive immune response requires waves of T-cell clonal expansion on contact with altered self and contraction after elimination of antigen. In the case of persisting antigen, as occurs for example in cytomegalovirus or Epstein–Barr virus infection, this critical process can become dysregulated and responding T-cells enter into a dysfunctional senescent state. Longitudinal studies suggest that the presence of increased numbers of such T-cells is a poor prognostic factor for survival in the very elderly. Understanding the nature of the defects in these T-cells might facilitate intervention to improve immunity in the elderly. The process of clonal expansion under chronic antigenic stress can be modelled in vitro using continuously cultured T-cells. Here, we have used cDNA array technology to investigate differences in gene expression in a set of five different T-cell clones at early, middle and late passage in culture. Differentially expressed genes were confirmed by real-time polymerase chain reaction, and relationships between these assessed using Ingenuity Systems evidence-based association analysis. Several genes and chemokines related to induction of apoptosis and signal transduction pathways regulated by transforming growth factor β (TGFβ), epidermal growth factor (EGF), fos and β-catenin were altered in late compared to early passage cells. These pathways and affected genes may play a significant role in driving the cellular senescent phenotype and warrant further investigation as potential biomarkers of aging and senescence. These genes may additionally provide targets for intervention.
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Affiliation(s)
- Dawn J Mazzatti
- Unilever Corporate Research, Colworth Park, Sharnbrook, Bedford MK44 1LQ, UK.
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13
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Wheaton K, Riabowol K. Protein kinase C delta blocks immediate-early gene expression in senescent cells by inactivating serum response factor. Mol Cell Biol 2004; 24:7298-311. [PMID: 15282327 PMCID: PMC479731 DOI: 10.1128/mcb.24.16.7298-7311.2004] [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: 01/21/2023] Open
Abstract
Fibroblasts lose the ability to replicate in response to growth factors and become unable to express growth-associated immediate-early genes, including c-fos and egr-1, as they become senescent. The serum response factor (SRF), a major transcriptional activator of immediate-early gene promoters, loses the ability to bind to the serum response element (SRE) and becomes hyperphosphorylated in senescent cells. We identify protein kinase C delta (PKC delta) as the kinase responsible for inactivation of SRF both in vitro and endogenously in senescent cells. This is due to a higher level of PKC delta activity as cells age, production of the PKC delta catalytic fragment, and its nuclear localization in senescent but not in low-passage-number cells. The phosphorylation of T160 of SRF by PKC delta in vitro and in vivo led to loss of SRF DNA binding activity. Both the PKC delta inhibitor rottlerin and ectopic expression of a dominant negative form of PKC delta independently restored SRE-dependent transcription and immediate-early gene expression in senescent cells. Modulation of PKC delta activity in vivo with rottlerin or bistratene A altered senescent- and young-cell morphology, respectively. These observations support the idea that the coordinate transcriptional inhibition of several growth-associated genes by PKC delta contributes to the senescent phenotype.
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Affiliation(s)
- Keith Wheaton
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Centre, University of Calgary, Calgary, Alberta, Canada
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Milanović D, Milosević J, Kanazir S, Rakić L, Ruzdijić S. Effect of amphetamine and phencyclidine on DNA-binding activities of serum response and dyad symmetry elements. Neurochem Int 2003; 42:409-17. [PMID: 12510024 DOI: 10.1016/s0197-0186(02)00133-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Acute administration of D-amphetamine sulphate (AMPH) and (1-[1-phenylcyclohexyl]piperidine hydrochloride) (phencyclidine; PCP) produces a characteristic spatio-temporal distribution of c-Fos protein in the brain. As transcriptional mechanisms underlying the induction of c-fos gene expression may be regulated in a stimulus-specific manner, we have analyzed the binding activities of serum response element (SRE), dyad symmetry element (DSE) and calcium response element (CRE), the major regulatory sites of the c-fos promoter. Electrophoretic mobility shift showed that SRE binding activity was increased for 50-60%, 2-6h after AMPH, while treatment with PCP resulted in light decrease of SRE binding activity throughout the same time period. Co-administration of AMPH and PCP induced gradual increase of SRE binding activity, reaching maximum (86%) at 6h. Binding of nuclear proteins to DSE sequence was increased 1-2h after administration of AMPH (72-87%) and remained elevated till the end of the time window observed. PCP and AMPH/PCP caused different temporal profile of DSE binding with peak (40-54%) 4-6h after administration. In contrast, DNA-binding activity of the CRE sequences remained unchanged throughout the time period of 6h under all conditions. Finally, supershift analysis clearly demonstrated presence of SRF and c-Fos protein in the transcriptional complexes bound to SRE and DSE sequences irrespective to AMPH, PCP or combined treatment. These findings also showed that the presence of c-Fos protein in SRE and DSE nucleocomplex support the hypothesis concerning autoregulation of c-fos gene expression during psychostimulant action in vivo.
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Affiliation(s)
- Desanka Milanović
- Laboratory of Molecular Neurobiology, Department of Neurobiology and Immunology, Institute for Biological Research, 29 Novembra 142, 11060 Belgrade, Yugoslavia
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15
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Kyng KJ, May A, Brosh RM, Cheng WH, Chen C, Becker KG, Bohr VA. The transcriptional response after oxidative stress is defective in Cockayne syndrome group B cells. Oncogene 2003; 22:1135-49. [PMID: 12606941 DOI: 10.1038/sj.onc.1206187] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cockayne syndrome (CS) is a human hereditary disease belonging to the group of segmental progerias, and the clinical phenotype is characterized by postnatal growth failure, neurological dysfunction, cachetic dwarfism, photosensitivity, sensorineural hearing loss, and retinal degradation. CS-B cells are defective in transcription-coupled DNA repair, base excision repair, transcription, and chromatin structural organization. Using array analysis, we have examined the expression profile in CS complementation group B (CS-B) fibroblasts after exposure to oxidative stress (H2O2) before and after complete complementation with the CSB gene. The following isogenic cell lines were compared: CS-B cells (CS-B null), CS-B cells complemented with wild-type CSB (CS-B wt), and a stably transformed cell line with a point mutation in the ATPase domain of CSB (CS-B ATPase mutant). In the wt rescued cells, we detected significant induction (two-fold) of 112 genes out of the 6912 analysed. The patterns suggested an induction or upregulation of genes involved in several DNA metabolic processes including DNA repair, transcription, and signal transduction. In both CS-B mutant cell lines, we found a general deficiency in transcription after oxidative stress, suggesting that the CSB protein influenced the regulation of transcription of certain genes. Of the 6912 genes, 122 were differentially regulated by more than two-fold. Evidently, the ATPase function of CSB is biologically important as the deficiencies seen in the ATPase mutant cells are very similar to those observed in the CS-B-null cells. Some major defects are in the transcription of genes involved in DNA repair, signal transduction, and ribosomal functions.
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Affiliation(s)
- Kasper J Kyng
- Laboratory of Molecular Gerontology, National Institute on Aging, 5600 Nathan Schock Drive, National Institute of Health, Baltimore, MD 21224, USA
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Abstract
In attempt to meet tissue demands for proper blood flow, the vasculature alters its structure, simultaneously responding to both physical and chemical stresses. Substantial information has emerged in this field of study, particularly concerning the roles of the endothelium and smooth muscle cells in relation to signaling pathways for mechanotransduction. As a first line of defense upon exposure to various stressors, the endothelium and smooth muscle cells respond with adaptive cellular modifications. One prime example of these modifications is the cellular response to oxidative stress as evidenced by accumulated data. A recent proposal of the inflammatory hypothesis of vascular aging emphasized that stress-induced vascular aging may be the primary event that underlies the general aging phenomenon of systemic dysfunction.
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Affiliation(s)
- B P Yu
- Department of Physiology, University of Texas Health Science Center, Mail code 7756, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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17
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Wheaton K, Sampsel K, Boisvert FM, Davy A, Robbins S, Riabowol K. Loss of functional caveolae during senescence of human fibroblasts. J Cell Physiol 2001; 187:226-35. [PMID: 11268002 DOI: 10.1002/jcp.1071] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Primary human fibroblasts have a finite replicative lifespan in culture that culminates in a unique state of growth arrest, termed senescence that is accompanied by distinct morphological and biochemical alterations. Senescent cell responses to extracellular stimuli are believed to be altered at a point after receptors are bound by ligand, leading to improper integration of the signals which initiate DNA replication. In this study we demonstrate that one of the key organizing membrane microdomains for receptor signaling, caveolae, are absent in senescent cells. A comparison of young and senescent cells indicated that senescent cells contained a higher total amount of caveolins 1 and 2 but had significantly less of both proteins in the caveolar fraction. Additionally, caveolar fractions from senescent cells completely lacked the tyrosine-kinase activity associated with functional caveolae. Furthermore, old cells had little caveolar protein exposed to the outer plasma membrane as estimated by using an in vivo biotinylation assay and no detectable caveolin 1 on the cell surface when processed for immunofluoresence and confocal microscopy. Together, these data suggest that a fundamental loss of signal integration at the plasma membrane of senescent cells is due to the loss of signaling competent caveolae.
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Affiliation(s)
- K Wheaton
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Centre, University of Calgary, Heritage Medical Research Building, Calgary Alberta, Canada
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18
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Grillari J, Hohenwarter O, Grabherr RM, Katinger H. Subtractive hybridization of mRNA from early passage and senescent endothelial cells. Exp Gerontol 2000; 35:187-97. [PMID: 10767578 DOI: 10.1016/s0531-5565(00)00080-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Regulation of cellular processes that eventually lead to a state of growth arrest is an important manifestation of in vitro cellular senescence caused and accompanied by variations of the gene expression pattern. Whereas these changes at the mRNA level have been studied mainly in fibroblast cultures, we concentrated on endothelial cells that represent an accepted model for vascular systems and may be involved in the pathogenesis of diseases related to aging. To isolate differentially expressed genes, we created a subtractive cDNA library using mRNA from senescent (35 passages) and young (five passages) human umbilical vein endothelial cells (HUVECs). Candidate clones were isolated from the cDNA library, differential expression was confirmed by Northern blot analyses and sequences were compared with a genbank data base. Because many mRNAs were below the detection limit of Northern blot analysis, we were forced to establish a more sensitive PCR based method (ATAC-PCR) to quantify and confirm altered levels of gene expression. Several mRNAs were found to be upregulated in senescent HUVECs including two components of the extracellular matrix (ECM): plasminogen activator inhibitor and fibronectin. Elevated expression of both has already been described in senescent cells. The mRNAs of TGF-beta-inducible gene H3 (beta-IG-H3; ECM protein), insulin-like growth factor binding protein (IGFBP-3), p53-inducible gene (PIG3) a protein involved in vesicular transport (SEC13R) and ribosomal protein L28 have likewise been shown to be preferentially expressed in senescent cells. Because studies support the involvement of ECM components, TGF-beta and p53 in tumor suppressing mechanisms, our data supports the hypothesis that cellular senescence and upregulation of ECM proteins may be associated with tumor preventive functions.
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Affiliation(s)
- J Grillari
- Institute of Applied Microbiology, University of Agricultural Sciences, Muthgasse 18, Vienna, Austria.
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Abstract
Reactive oxygen species are produced by all aerobic cells and are widely believed to play a pivotal role in aging as well as a number of degenerative diseases. The consequences of the generation of oxidants in cells does not appear to be limited to promotion of deleterious effects. Alterations in oxidative metabolism have long been known to occur during differentiation and development. Experimental perturbations in cellular redox state have been shown to exert a strong impact on these processes. The discovery of specific genes and pathways affected by oxidants led to the hypothesis that reactive oxygen species serve as subcellular messengers in gene regulatory and signal transduction pathways. Additionally, antioxidants can activate numerous genes and pathways. The burgeoning growth in the number of pathways shown to be dependent on oxidation or antioxidation has accelerated during the last decade. In the discussion presented here, we provide a tabular summary of many of the redox effects on gene expression and signaling pathways that are currently known to exist.
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Affiliation(s)
- R G Allen
- Lankenau Medical Research Center, Thomas Jefferson University, Wynnewood, PA 19106, USA
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Flück M, Waxham MN, Hamilton MT, Booth FW. Skeletal muscle Ca(2+)-independent kinase activity increases during either hypertrophy or running. J Appl Physiol (1985) 2000; 88:352-8. [PMID: 10642401 DOI: 10.1152/jappl.2000.88.1.352] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spikes in free Ca(2+) initiate contractions in skeletal muscle cells, but whether and how they might signal to transcription factors in skeletal muscles of living animals is unknown. Since previous studies in non-muscle cells have shown that serum response factor (SRF) protein, a transcription factor, is phosphorylated rapidly by Ca(2+)/calmodulin (CaM)-dependent protein kinase after rises in intracellular Ca(2+), we measured enzymatic activity that phosphorylates SRF (designated SRF kinase activity). Homogenates from 7-day-hypertrophied anterior latissimus dorsi muscles of roosters had more Ca(2+)-independent SRF kinase activity than their respective control muscles. However, no differences were noted in Ca(2+)/CaM-dependent SRF kinase activity between control and trained muscles. To determine whether the Ca(2+)-independent and Ca(2+)/CaM-dependent forms of Ca(2+)/CaM-dependent protein kinase II (CaMKII) might contribute to some of the SRF kinase activity, autocamtide-3, a synthetic substrate that is specific for CaMKII, was employed. While the Ca(2+)-independent form of CaMKII was increased, like the Ca(2+)-independent form of SRF kinase, no alteration in CaMKII occurred at 7 days of stretch overload. These observations suggest that some of SRF phosphorylation by skeletal muscle extracts could be due to CaMKII. To determine whether this adaptation was specific to the exercise type (i.e., hypertrophy), similar measurements were made in the white vastus lateralis muscle of rats that had completed 2 wk of voluntary running. Although Ca(2+)-independent SRF kinase was increased, no alteration occurred in Ca(2+)/CaM-dependent SRF kinase activity. Thus any role of Ca(2+)-independent SRF kinase signaling has downstream modulators specific to the exercise phenotype.
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Affiliation(s)
- M Flück
- Department of Integrative Biology and Pharmacology, University of Texas Medical School, Houston, Texas 77030, USA
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Affiliation(s)
- Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri‐Columbia, Columbia, Missouri 65211
| | - Amitabha Chakrabarti
- Department of Veterinary Pathobiology, University of Missouri‐Columbia, Columbia, Missouri 65211
| | - Julie Hedrick
- Department of Zoology, University of Wisconsin‐Madison, Madison, Wisconsin 53706
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D'Ippolito G, Schiller PC, Ricordi C, Roos BA, Howard GA. Age-related osteogenic potential of mesenchymal stromal stem cells from human vertebral bone marrow. J Bone Miner Res 1999; 14:1115-22. [PMID: 10404011 DOI: 10.1359/jbmr.1999.14.7.1115] [Citation(s) in RCA: 620] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mesenchymal stem cells (MSCs) residing in bone marrow (BM) are the progenitors for osteoblasts and for several other cell types. In humans, the age-related decrease in bone mass could reflect decreased osteoblasts secondary to an age-related loss of osteoprogenitors. To test this hypothesis, BM cells were isolated from vertebral bodies of thoracic and lumbar spine (T1-L5) from 41 donors (16 women and 25 men) of various ages (3-70 years old) after death from traumatic injury. Primary cultures were grown in alpha modified essential medium with fetal bovine serum for 13 days until adherent cells formed colonies (CFU-Fs). Colonies that stained positive for alkaline phosphatase activity (CFU-F/ALP+) were considered to have osteogenic potential. BM nucleated cells were plated (0.5, 1, 2.5, 5, or 10 x 106 cells/10-cm dish) and grown in dexamethasone (Dex), which promotes osteoblastic differentiation. The optimal plating efficiency using BM-derived cells from donors of various ages was 5 x 106 cells/10-cm dish. BM-derived cells were also grown in the absence of Dex at this plating density. At the optimal plating density, in the presence of Dex, the number of CFU-F/ALP+ present in the BM of the younger donors (3-36 years old) was 66.2 +/- 9.6 per 106 cells (mean +/- SEM), but only 14.7 +/- 2.6 per 106 cells in the older donors (41-70 years old). With longer-term culture (4-5 weeks) of these BM cells in medium containing 10 mM beta-glycerophosphate and 100 microg/ml ascorbic acid, the extracellular matrix mineralized, a result consistent with mature osteoblastic function. These results demonstrate that the number of MSCs with osteogenic potential (CFU-F/ALP+) decreases early during aging in humans and may be responsible for the age-related reduction in osteoblast number. Our results are particularly important in that the vertebrae are a site of high turnover osteoporosis and, possibly, the earliest site of bone loss in age-related osteoporosis.
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Affiliation(s)
- G D'Ippolito
- Geriatric Research, Education, and Clinical Center and Research Service, Veterans Affairs Medical Center, Miami, Florida 33125, USA
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23
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Meyyappan M, Wheaton K, Riabowol KT. Decreased expression and activity of the immediate-early growth response (Egr-1) gene product during cellular senescence. J Cell Physiol 1999; 179:29-39. [PMID: 10082129 DOI: 10.1002/(sici)1097-4652(199904)179:1<29::aid-jcp4>3.0.co;2-d] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Human diploid fibroblasts (HDFs) undergo a limited number of population doublings in culture before reaching the end of their proliferative life span, an event termed in vitro cellular senescence. Considerable evidence suggests that altered expression of key genes involved in the mitogenic response may be responsible for the inability of senescent cells to proliferate. Here we examined the expression and activity of the early growth response-1 (egr-1) gene, an "immediate-early" gene that is believed to link extracellular mitogenic signals to cell-cycle progression. We found that egr-1 was strongly downregulated in senescent HDFs at the level of mRNA, protein, and DNA binding activity. Decreased DNA binding activity of Egr-1 in vitro corresponded to decreased transcriptional activation in vivo. To further understand the mechanism of egr-1 downregulation, we examined the potential role of the serum response elements (SREs) present in the egr-1 promoter. Electrophoretic mobility shift studies using young and old cell nuclear extracts showed a marked decrease in serum response factor (SRF) binding activity to the SRE in old compared to young cells. Loss of SRF binding activity has been correlated with the loss of expression of another growth-related immediate-early gene (c-fos). These results suggest a common mechanism for the downregulation of c-fos, egr-1, and other SRE-dependent, mitogen-responsive genes during cellular senescence.
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Affiliation(s)
- M Meyyappan
- Department of Medical Science, Southern Alberta Cancer Research Center, University of Calgary Health Sciences Center, Canada
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24
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Sloan MA, Levenson J, Tran Q, Kerbeshian M, Block GD, Eskin A. Aging affects the ocular circadian pacemaker of Aplysia californica. J Biol Rhythms 1999; 14:151-9. [PMID: 10194652 DOI: 10.1177/074873099129000542] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The eye of Aplysia has been used to explore various aspects of circadian rhythms. The authors discovered that age has profound effects on the circadian rhythm of nerve impulses from the eye. With age, there was a significant decrease in the amplitude of the rhythm. The decrease appeared to be continuous over the life span of the animal and was observed both in vitro and in vivo. The free-running period and phase angle of the rhythm steadily increased with age, indicating that the pacemaker itself was affected by age. Rates of transcription and translation were significantly increased with age, suggesting that age-associated alterations of the pacemaker may occur through changes in macromolecular synthesis. Interestingly, eyes from some older (> or = 10 months) animals had "cloudy" lenses (cataracts). Highly damped or arrhythmic rhythms always were seen in eyes with cloudy lenses. Morphology of eyes with cloudy lenses indicated severe retinal degeneration. No such degeneration was observed in eyes with clear lenses that were used in the analysis of the rhythm with age.
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Affiliation(s)
- M A Sloan
- Department of Biology and Biochemistry, University of Houston, TX 77204-5934, USA
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Wu L, Xia YP, Roth SI, Gruskin E, Mustoe TA. Transforming growth factor-beta1 fails to stimulate wound healing and impairs its signal transduction in an aged ischemic ulcer model: importance of oxygen and age. THE AMERICAN JOURNAL OF PATHOLOGY 1999; 154:301-9. [PMID: 9916944 PMCID: PMC1853440 DOI: 10.1016/s0002-9440(10)65276-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/14/1998] [Indexed: 01/27/2023]
Abstract
Clinical trials of exogenous growth factors in treating chronic wounds have been less successful than expected. One possible explanation is that most studies used animal models of acute wounds in young animals, whereas most chronic wounds occur in elderly patients with tissue ischemia. We described an animal model of age- and ischemia-impaired wound healing and analyzed the wound-healing response as well as the transforming growth factor (TGF)-beta1 effect in this model. Rabbits of increasing ages were made ischemic in the ear where dermal ulcers were created. Histological analysis showed that epithelium ingrowth and granulation tissue deposition were significantly impaired with increased age under ischemia. TGF-beta1 stimulated wound repair under both ischemic and non-ischemic conditions in young animals, although it showed no statistical difference in aged animals. Procollagen mRNA expression decreased under ischemic conditions and with aging. Neither TGF-beta1 nor procollagen alpha1(I) mRNA expression increased in response to TGF-beta1 treatment under ischemia in aged animals. Therefore, the wound-healing process is impaired additively by aging and ischemia. The lack of a wound-healing response to TGF-beta1 in aged ischemic wounds may play a role in the chronic wounds.
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Affiliation(s)
- L Wu
- Department of Surgery, Northwestern University Medical School, Chicago, Illinois, USA
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Meyyappan M, Wong H, Hull C, Riabowol KT. Increased expression of cyclin D2 during multiple states of growth arrest in primary and established cells. Mol Cell Biol 1998; 18:3163-72. [PMID: 9584157 PMCID: PMC108898 DOI: 10.1128/mcb.18.6.3163] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cyclin D2 is a member of the family of D-type cyclins that is implicated in cell cycle regulation, differentiation, and oncogenic transformation. To better understand the role of this cyclin in the control of cell proliferation, cyclin D2 expression was monitored under various growth conditions in primary human and established murine fibroblasts. In different states of cellular growth arrest initiated by contact inhibition, serum starvation, or cellular senescence, marked increases (5- to 20-fold) were seen in the expression levels of cyclin D2 mRNA and protein. Indirect immunofluorescence studies showed that cyclin D2 protein localized to the nucleus in G0, suggesting a nuclear function for cyclin D2 in quiescent cells. Cyclin D2 was also found to be associated with the cyclin-dependent kinases CDK2 and CDK4 but not CDK6 during growth arrest. Cyclin D2-CDK2 complexes increased in amounts but were inactive as histone H1 kinases in quiescent cells. Transient transfection and needle microinjection of cyclin D2 expression constructs demonstrated that overexpression of cyclin D2 protein efficiently inhibited cell cycle progression and DNA synthesis. These data suggest that in addition to a role in promoting cell cycle progression through phosphorylation of retinoblastoma family proteins in some cell systems, cyclin D2 may contribute to the induction and/or maintenance of a nonproliferative state, possibly through sequestration of the CDK2 catalytic subunit.
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Affiliation(s)
- M Meyyappan
- Departments of Medical Science, Southern Alberta Cancer Research Center, Calgary, Alberta, Canada T2N 4N1
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