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Wang Y, Wang Y, Zhang J, Shi Z, Liu J. LncRNA NONHSAT227443.1 Confers Esophageal Squamous Cell Carcinoma Chemotherapy Resistance by Activating PI3K/AKT Signaling via Targeting MRTFB. Technol Cancer Res Treat 2024; 23:15330338241274369. [PMID: 39150441 PMCID: PMC11329966 DOI: 10.1177/15330338241274369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 06/04/2024] [Accepted: 07/08/2024] [Indexed: 08/17/2024] Open
Abstract
INTRODUCTION Esophageal cancer presents significant challenges due to limited treatment options and poor prognosis, particularly in advanced stages. Dysregulated long non-coding RNAs (lncRNAs) are implicated in cancer progression and treatment resistance. This study investigated the roles of dysregulated lncRNA NONHSAT227443.1, identified through lncRNA-seq, and its downstream target gene MRTFB in esophageal squamous cell carcinoma (ESCC). METHODS Dysregulated lncRNAs were identified through lncRNA-seq in esophageal cancer tissues with varying chemotherapy response. The regulatory interaction of overexpressed NONHSAT227443.1 was assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Functional assays, including cell viability, cell proliferation, and flow cytometry analyses, were performed to comprehensively investigate the influence of NONHSAT227443.1 and its downstream molecules on ESCC. RESULTS NONHSAT227443.1 was significantly overexpressed in paclitaxel plus platinum chemotherapy non-responders and esophageal cancer cell lines. Chemotherapy exposure led to diminished NONHSAT227443.1 expression. NONHSAT227443.1 negatively regulated MRTFB expression, and their combined dysregulation correlated with increased cancer activity, proliferation, and suppressed apoptosis. Diminished MRTFB expression was associated with PI3K/AKT pathway activation. CONCLUSION Our study provides insights into NONHSAT227443.1 and MRTFB roles in esophageal cancer, contributing to aggressive traits and treatment resistance. NONHSAT227443.1 and MRTFB may serve as potential therapeutic targets to enhance the response to paclitaxel plus platinum chemotherapy in non-responsive cases.
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Affiliation(s)
- Yuchen Wang
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China
- Graduate School, Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Yingying Wang
- Department of Functional Region of Diagnosis, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jinze Zhang
- Department of Thoracic Endoscopy Room, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China
| | - Zhihua Shi
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Junfeng Liu
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China
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Speight P, Rozycki M, Venugopal S, Szászi K, Kofler M, Kapus A. Myocardin-related transcription factor and serum response factor regulate cilium turnover by both transcriptional and local mechanisms. iScience 2021; 24:102739. [PMID: 34278253 PMCID: PMC8261663 DOI: 10.1016/j.isci.2021.102739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 11/02/2020] [Accepted: 06/15/2021] [Indexed: 12/31/2022] Open
Abstract
Turnover of the primary cilium (PC) is critical for proliferation and tissue homeostasis. Each key component of the PC resorption machinery, the HEF1/Aurora kinase A (AurA)/HDAC6 pathway harbors cis-elements potentially targeted by the transcriptional co-activator myocardin-related transcription factor (MRTF) and/or its partner serum response factor (SRF). Thus we investigated if MRTF and/or SRF regulate PC turnover. Here we show that (1) both MRTF and SRF are indispensable for serum-induced PC resorption, and (2) they act via both transcriptional and local mechanisms. Intriguingly, MRTF and SRF are present in the basal body and/or the PC, and serum facilitates ciliary MRTF recruitment. MRTF promotes the stability and ciliary accumulation of AurA and facilitates SRF phosphorylation. Ciliary SRF interacts with AurA and HDAC6. MRTF also inhibits ciliogenesis. It interacts with and is required for the correct localization of the ciliogenesis modulator CEP290. Thus, MRTF and SRF are critical regulators of PC assembly and/or disassembly, acting both as transcription factors and as PC constituents.
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Affiliation(s)
- Pam Speight
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
| | - Matthew Rozycki
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
| | - Shruthi Venugopal
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
| | - Katalin Szászi
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
- Department of Surgery, University of Toronto, Toronto, ON M5B 1T8, Canada
| | - Michael Kofler
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
| | - András Kapus
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, University of Toronto, Room 621, 209 Victoria Street, Toronto, ON M5B 1T8, Canada
- Department of Surgery, University of Toronto, Toronto, ON M5B 1T8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5B 1T8, Canada
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Kansakar U, Jankauskas SS, Gambardella J, Santulli G. Targeting the phenotypic switch of vascular smooth muscle cells to tackle atherosclerosis. Atherosclerosis 2021; 324:117-120. [PMID: 33832772 PMCID: PMC8195811 DOI: 10.1016/j.atherosclerosis.2021.03.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 03/19/2021] [Accepted: 03/25/2021] [Indexed: 02/08/2023]
Affiliation(s)
- Urna Kansakar
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York City, 10461, NY, United States
| | - Stanislovas S Jankauskas
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York City, 10461, NY, United States; Department of Medicine (Division of Cardiology), Albert Einstein College of Medicine - Montefiore University Hospital, New York City, 10461, NY, United States
| | - Jessica Gambardella
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York City, 10461, NY, United States; Department of Medicine (Division of Cardiology), Albert Einstein College of Medicine - Montefiore University Hospital, New York City, 10461, NY, United States; Department of Advanced Biomedical Sciences, "Federico II" University, Naples, 80131, Italy
| | - Gaetano Santulli
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York City, 10461, NY, United States; Department of Medicine (Division of Cardiology), Albert Einstein College of Medicine - Montefiore University Hospital, New York City, 10461, NY, United States; Department of Advanced Biomedical Sciences, "Federico II" University, Naples, 80131, Italy; International Translational Research and Medical Education (ITME), Naples, 80100, Italy.
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Kinase-Independent Functions of MASTL in Cancer: A New Perspective on MASTL Targeting. Cells 2020; 9:cells9071624. [PMID: 32640605 PMCID: PMC7407770 DOI: 10.3390/cells9071624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 02/07/2023] Open
Abstract
Microtubule-associated serine/threonine kinase-like (MASTL; Greatwall) is a well-characterized kinase, whose catalytic role has been extensively studied in relation to cell-cycle acceleration. Importantly, MASTL has been implicated to play a substantial role in cancer progression and subsequent studies have shown that MASTL is a significant regulator of the cellular actomyosin cytoskeleton. Several kinases have non-catalytic properties, which are essential or even sufficient for their functions. Likewise, MASTL functions have been attributed both to kinase-dependent phosphorylation of downstream substrates, but also to kinase-independent regulation of the actomyosin contractile machinery. In this review, we aimed to highlight the catalytic and non-catalytic roles of MASTL in proliferation, migration, and invasion. Further, we discussed the implications of this dual role for therapeutic design.
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MRTFB suppresses colorectal cancer development through regulating SPDL1 and MCAM. Proc Natl Acad Sci U S A 2019; 116:23625-23635. [PMID: 31690663 DOI: 10.1073/pnas.1910413116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Myocardin-related transcription factor B (MRTFB) is a candidate tumor-suppressor gene identified in transposon mutagenesis screens of the intestine, liver, and pancreas. Using a combination of cell-based assays, in vivo tumor xenograft assays, and Mrtfb knockout mice, we demonstrate here that MRTFB is a human and mouse colorectal cancer (CRC) tumor suppressor that functions in part by inhibiting cell invasion and migration. To identify possible MRTFB transcriptional targets, we performed whole transcriptome RNA sequencing in MRTFB siRNA knockdown primary human colon cells and identified 15 differentially expressed genes. Among the top candidate tumor-suppressor targets were melanoma cell adhesion molecule (MCAM), a known tumor suppressor, and spindle apparatus coiled-coil protein 1 (SPDL1), which has no confirmed role in cancer. To determine whether these genes play a role in CRC, we knocked down the expression of MCAM and SPDL1 in human CRC cells and showed significantly increased invasion and migration of tumor cells. We also showed that Spdl1 expression is significantly down-regulated in Mrtfb knockout mouse intestine, while lower SPDL1 expression levels are significantly associated with reduced survival in CRC patients. Finally, we show that depletion of MCAM and SPDL1 in human CRC cells significantly increases tumor development in xenograft assays, further confirming their tumor-suppressive roles in CRC. Collectively, our findings demonstrate the tumor-suppressive role of MRTFB in CRC and identify several genes, including 2 tumor suppressors, that act downstream of MRTFB to regulate tumor growth and survival in CRC patients.
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Chen B, Li Z, Feng Y, Wu X, Xu Y. Myocardin-related transcription factor A (MRTF-A) mediates doxorubicin-induced PERP transcription in colon cancer cells. Biochem Biophys Res Commun 2018; 503:1732-1739. [DOI: 10.1016/j.bbrc.2018.07.106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 07/21/2018] [Indexed: 10/28/2022]
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Divergent Regulation of Actin Dynamics and Megakaryoblastic Leukemia-1 and -2 (Mkl1/2) by cAMP in Endothelial and Smooth Muscle Cells. Sci Rep 2017. [PMID: 28623279 PMCID: PMC5473867 DOI: 10.1038/s41598-017-03337-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Proliferation and migration of vascular smooth muscle cells (VSMCs) or endothelial cell (ECs) promote or inhibit, respectively, restenosis after angioplasty, vein graft intimal thickening and atherogenesis. Here we investigated the effects of cAMP-induced cytoskeletal remodelling on the serum response factor (SRF) co-factors Megakaryoblastic Leukemia-1 and -2 (MKL1 and MKL2) and their role in controlling VSMC and EC proliferation and migration. Elevation of cAMP using forskolin, dibutyryl-cAMP (db-cAMP), BAY60-6583 or Cicaprost induced rapid cytoskeleton remodelling and inhibited proliferation and migration in VSMCs but not EC. Furthermore, elevated cAMP inhibited mitogen-induced nuclear-translocation of MKL1 and MKL2 in VSMCs but not ECs. Forskolin also significantly inhibited serum response factor (SRF)-dependent reporter gene (SRE-LUC) activity and mRNA expression of pro-proliferative and pro-migratory MKL1/2 target genes in VSMCs but not in ECs. In ECs, MKL1 was constitutively nuclear and MKL2 cytoplasmic, irrespective of mitogens or cAMP. Pharmacological or siRNA inhibition of MKL1 significantly inhibited the proliferation and migration of VSMC and EC. Our new data identifies and important contribution of MKL1/2 to explaining the strikingly different response of VSMCs and ECs to cAMP elevation. Elucidation of these pathways promises to identify targets for specific inhibition of VSMC migration and proliferation.
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Seifert A, Posern G. Tightly controlled MRTF-A activity regulates epithelial differentiation during formation of mammary acini. Breast Cancer Res 2017; 19:68. [PMID: 28592291 PMCID: PMC5463372 DOI: 10.1186/s13058-017-0860-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/25/2017] [Indexed: 01/06/2023] Open
Abstract
Background Myocardin-related transcription factors (MRTF) A and B link actin dynamics and mechanotransduction to gene expression. In mice, MRTF-A is involved in mammary gland differentiation, but its role in human mammary epithelial cells remains unclear. Methods Three-dimensional cultures of human mammary epithelial MCF10A cells were used to model acinar morphogenesis. Stable MRTF-A knockdown, MRTF-A/B rescue and MRTF-A/B overexpression was established to characterize the functional role during morphogenesis using confocal microscopy and expression analysis. Breast cancer patient databases were analyzed for MRTF-A expression. Results We showed that a precise temporal control of MRTFs is required for normal morphogenesis of MCF10A mammary acini. MRTF transcriptional activity, but not their protein amounts, is transiently induced during 3D acini formation. MRTF-A knockdown dramatically reduces acini size and prevents lumen formation. These effects are rescued by re-expression of MRTF-A, and partially by MRTF-B. Conversely, overexpression of MRTF-A and MRTF-B increases acini size, resulting in irregular spheroids without lumen and defective apico-basal polarity. These phenotypes correlate with deregulated expression of cell cycle inhibitors p21/Waf1, p27/Kip1 and altered phosphorylation of retinoblastoma protein. In MRTF overexpressing spheroids, proliferation and apoptosis are simultaneously increased at late stages, whilst neither occurs in control acini. MRTFs interfere with anoikis of the inner cells and cause an integrin switch from α6 to α5, repression of E-cadherin and induction of mesenchymal markers vimentin, Snai2 and Zeb1. Moreover, MRTF-overexpressing spheroids are insensitive to alteration in matrix stiffness. In two breast cancer cohorts, high expression of MRTF-A and known target genes was associated with decreased patient survival. Conclusion MRTF-A is required for proliferation and formation of mammary acini from luminal epithelial cells. Conversely, elevated MRTF activity results in pre-malignant spheroid formation due to defective proliferation, polarity loss and epithelial-mesenchymal transition. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0860-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anja Seifert
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany
| | - Guido Posern
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany.
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9
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Gosselin P, Rando G, Fleury-Olela F, Schibler U. Unbiased identification of signal-activated transcription factors by barcoded synthetic tandem repeat promoter screening (BC-STAR-PROM). Genes Dev 2017; 30:1895-907. [PMID: 27601530 PMCID: PMC5024686 DOI: 10.1101/gad.284828.116] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/02/2016] [Indexed: 12/23/2022]
Abstract
Gosselin et al. designed a widely applicable method, dubbed BC-STAR-PROM, to identify signal-activated TFs without any prior knowledge of their properties. To establish proof of concept for BC-STAR-PROM, they applied it to the identification of TFs induced by drugs affecting actin and tubulin cytoskeleton dynamics. The discovery of transcription factors (TFs) controlling pathways in health and disease is of paramount interest. We designed a widely applicable method, dubbed barcorded synthetic tandem repeat promoter screening (BC-STAR-PROM), to identify signal-activated TFs without any a priori knowledge about their properties. The BC-STAR-PROM library consists of ∼3000 luciferase expression vectors, each harboring a promoter (composed of six tandem repeats of synthetic random DNA) and an associated barcode of 20 base pairs (bp) within the 3′ untranslated mRNA region. Together, the promoter sequences encompass >400,000 bp of random DNA, a sequence complexity sufficient to capture most TFs. Cells transfected with the library are exposed to a signal, and the mRNAs that it encodes are counted by next-generation sequencing of the barcodes. This allows the simultaneous activity tracking of each of the ∼3000 synthetic promoters in a single experiment. Here we establish proof of concept for BC-STAR-PROM by applying it to the identification of TFs induced by drugs affecting actin and tubulin cytoskeleton dynamics. BC-STAR-PROM revealed that serum response factor (SRF) is the only immediate early TF induced by both actin polymerization and microtubule depolymerization. Such changes in cytoskeleton dynamics are known to occur during the cell division cycle, and real-time bioluminescence microscopy indeed revealed cell-autonomous SRF–myocardin-related TF (MRTF) activity bouts in proliferating cells.
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Affiliation(s)
- Pauline Gosselin
- Department of Molecular Biology, University of Geneva, CH-1211 Geneva, Switzerland
| | - Gianpaolo Rando
- Department of Molecular Biology, University of Geneva, CH-1211 Geneva, Switzerland
| | | | - Ueli Schibler
- Department of Molecular Biology, University of Geneva, CH-1211 Geneva, Switzerland
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10
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Cheng X, Yang Y, Fan Z, Yu L, Bai H, Zhou B, Wu X, Xu H, Fang M, Shen A, Chen Q, Xu Y. MKL1 potentiates lung cancer cell migration and invasion by epigenetically activating MMP9 transcription. Oncogene 2015; 34:5570-81. [PMID: 25746000 DOI: 10.1038/onc.2015.14] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/17/2014] [Accepted: 01/07/2015] [Indexed: 12/24/2022]
Abstract
Malignant tumors are exemplified by excessive proliferation and aggressive migration/invasion contributing to increased mortality of cancer patients. Matrix metalloproteinase 9 (MMP9) expression is positively correlated with lung cancer malignancy. The mechanism underlying an elevated MMP9 expression is not clearly defined. We demonstrate here that the transcriptional modulator megakaryocytic leukemia 1 (MKL1) was activated by hypoxia and transforming growth factor (TGF-β), two prominent pro-malignancy factors, in cultured lung cancer cells. MKL1 levels were also increased in more invasive types of lung cancer in humans. Depletion of MKL1 in lung cancer cells attenuated migration and invasion both in vitro and in vivo. Overexpression of MKL1 potentiated the induction of MMP9 transcription by hypoxia and TGF-β, whereas MKL1 silencing diminished MMP9 expression. Of interest, MKL1 knockdown eliminated histone H3K4 methylation surrounding the MMP9 promoter. Further analyses revealed that MKL1 recruited ASH2, a component of the H3K4 methyltransferase complex, to activate MMP9 transcription. Depletion of ASH2 ameliorated cancer cell migration and invasion in an MMP9-dependent manner. Together our data indicate that MKL1 potentiates lung cancer cell migration and invasion by epigenetically activating MMP9 transcription.
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Affiliation(s)
- X Cheng
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China.,Jiangsu Institute of Nuclear Medicine, Wuxi, China
| | - Y Yang
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Z Fan
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - L Yu
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - H Bai
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - B Zhou
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - X Wu
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - H Xu
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - M Fang
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China.,Department of Nursing, Jiangsu Jiankang Vocational University, Nanjing, China
| | - A Shen
- Department of Key Laboratory of Inflammation and Molecular Targets, Medical College, Nantong University, Nantong, China
| | - Q Chen
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Y Xu
- Key Laboratory of Cardiovascular Disease and Department of Pathophysiology, Nanjing Medical University, Nanjing, China
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Yang S, Liu L, Xu P, Yang Z. MKL1 inhibits cell cycle progression through p21 in podocytes. BMC Mol Biol 2015; 16:1. [PMID: 25888165 PMCID: PMC4330937 DOI: 10.1186/s12867-015-0029-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 01/16/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The glomerular podocyte is a highly specialized cell type with the ability to ultrafilter blood and support glomerular capillary pressure. However, little is known about the genetic programs leading to this functionality or the final phenotype. RESULTS In the current study, we found that the expression of a myocardin/MKL family member, MKL1, was significantly upregulated during cell cycle arrest induced by a temperature switch in murine podocyte clone 5 (MPC5) cells. Further investigation demonstrated that overexpression of MKL1 led to inhibition of cell proliferation by decreasing the number of cells in S phase of the cell cycle. In contrast, MKL1 knockdown by RNA interference had the opposite effect, highlighting a potential role of MKL1 in blocking G1/S transition of the cell cycle in MPC5 cells. Additionally, using an RT(2) Profiler PCR Array, p21 was identified as a direct target of MKL1. We further revealed that MKL1 activated p21 transcription by recruitment to the CArG element in its promoter, thus resulting in cell cycle arrest. In addition, the expression of MKL1 is positively correlated with that of p21 in podocytes in postnatal mouse kidney and significantly upregulated during the morphological switch of podocytes from proliferation to differentiation. CONCLUSIONS Our observations demonstrate that MKL1 has physiological roles in the maturation and development of podocytes, and thus its misregulation might lead to glomerular and renal dysfunction.
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Affiliation(s)
- Shuang Yang
- Medical School, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, 94 Weijin Road, Tianjin, 300071, China.
| | - Lingjia Liu
- Medical School, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, 94 Weijin Road, Tianjin, 300071, China.
| | - Pengjuan Xu
- Tianjin University of Traditional Chinese Medicine, Tianjin, 300193, China.
| | - Zhuo Yang
- Medical School, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Nankai University, 94 Weijin Road, Tianjin, 300071, China.
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Myocardin related transcription factor A programs epigenetic activation of hepatic stellate cells. J Hepatol 2015; 62:165-74. [PMID: 25109772 DOI: 10.1016/j.jhep.2014.07.029] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/17/2014] [Accepted: 07/23/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Activation of hepatic stellate cells (HSCs) represents a key process in liver injury and, in the absence of intervention, leads to irreversible cirrhosis contributing significantly to the mortality of patients with liver disease. A missing link in the current understanding of HSC activation is the involvement of the epigenetic machinery. We investigated the role of the myocardin related transcription factor A (MRTF-A) in HSC activation. METHODS Liver fibrosis was induced in wild type (WT) and MRTF-A deficient (KO) mice by CCl4 injection. Expression of mRNA and protein was measured by real-time PCR, Western blotting, and immunohistochemistry. Protein binding to DNA was assayed by chromatin immunoprecipitation (ChIP). Knockdown of endogenous proteins was mediated by either small interfering RNA (siRNA) or short hairpin RNA (shRNA), carried by lentiviral particles. RESULTS KO mice exhibited resistance to CCl4-induced liver fibrosis compared to WT littermates. The expression of activated HSC signature genes was suppressed in the absence of MRTF-A. ChIP assays revealed that MRTF-A deficiency led to the erasure of key histone modifications, associated with transcriptional activation, such as H3K4 di- and tri-methylation, on the promoter regions of fibrogenic genes. Mechanistically, MRTF-A recruited a histone methyltransferase complex (COMPASS) to the promoters of fibrogenic genes to activate transcription. Silencing of individual COMPASS components dampened transactivation of fibrogenic genes in vitro and blocked liver fibrosis in mice. Oestradiol suppressed HSC activation by dampening the expression and binding activity of COMPASS. CONCLUSIONS Our data illustrate a novel mechanism that connects MRTF-A dependent histone H3K4 methylation to HSC activation.
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