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Venugopal S, Dan Q, Sri Theivakadadcham VS, Wu B, Kofler M, Layne MD, Connelly KA, Rzepka MF, Friedberg MK, Kapus A, Szászi K. Regulation of the RhoA exchange factor GEF-H1 by profibrotic stimuli through a positive feedback loop involving RhoA, MRTF, and Sp1. Am J Physiol Cell Physiol 2024; 327:C387-C402. [PMID: 38912734 DOI: 10.1152/ajpcell.00088.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 06/03/2024] [Accepted: 06/14/2024] [Indexed: 06/25/2024]
Abstract
RhoA and its effectors, the transcriptional coactivators myocardin-related transcription factor (MRTF) and serum response factor (SRF), control epithelial phenotype and are indispensable for profibrotic epithelial reprogramming during fibrogenesis. Context-dependent control of RhoA and fibrosis-associated changes in its regulators, however, remain incompletely characterized. We previously identified the guanine nucleotide exchange factor GEF-H1 as a central mediator of RhoA activation in renal tubular cells exposed to inflammatory or fibrotic stimuli. Here we found that GEF-H1 expression and phosphorylation were strongly elevated in two animal models of fibrosis. In the Unilateral Ureteral Obstruction mouse kidney fibrosis model, GEF-H1 was upregulated predominantly in the tubular compartment. GEF-H1 was also elevated and phosphorylated in a rat pulmonary artery banding (PAB) model of right ventricular fibrosis. Prolonged stimulation of LLC-PK1 tubular cells with tumor necrosis factor (TNF)-α or transforming growth factor (TGF)-β1 increased GEF-H1 expression and activated a luciferase-coupled GEF-H1 promoter. Knockdown and overexpression studies revealed that these effects were mediated by RhoA, cytoskeleton remodeling, and MRTF, indicative of a positive feedback cycle. Indeed, silencing endogenous GEF-H1 attenuated activation of the GEF-H1 promoter. Of importance, inhibition of MRTF using CCG-1423 prevented GEF-H1 upregulation in both animal models. MRTF-dependent increase in GEF-H1 was prevented by inhibition of the transcription factor Sp1, and mutating putative Sp1 binding sites in the GEF-H1 promoter eliminated its MRTF-dependent activation. As the GEF-H1/RhoA axis is key for fibrogenesis, this novel MRTF/Sp1-dependent regulation of GEF-H1 abundance represents a potential target for reducing renal and cardiac fibrosis.NEW & NOTEWORTHY We show that expression of the RhoA regulator GEF-H1 is upregulated in tubular cells exposed to fibrogenic cytokines and in animal models of kidney and heart fibrosis. We identify a pathway wherein GEF-H1/RhoA-dependent MRTF activation through its noncanonical partner Sp1 upregulates GEF-H1. Our data reveal the existence of a positive feedback cycle that enhances Rho signaling through control of both GEF-H1 activation and expression. This feedback loop may play an important role in organ fibrosis.
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Affiliation(s)
- Shruthi Venugopal
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Qinghong Dan
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Veroni S Sri Theivakadadcham
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Brian Wu
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Michael Kofler
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Matthew D Layne
- Department of Biochemistry & Cell Biology, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts, United States
| | - Kim A Connelly
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Mark F Rzepka
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Mark K Friedberg
- Division of Cardiology, Labatt Family Heart Center Toronto, Hospital for Sick Children, Toronto, Ontario, Canada
- Translational Medicine, Hospital for Sick Children Research Institute and University of Toronto, Toronto, Ontario, Canada
| | - András Kapus
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Katalin Szászi
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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Takahashi H, Fujimoto T, Yaoi T, Fushiki S, Itoh K. Leukemia inhibitory factor shortens primary cilia by upregulating C-C motif chemokine 2 in human neural stem/progenitor cells. Genes Cells 2023; 28:868-880. [PMID: 37837427 DOI: 10.1111/gtc.13074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/03/2023] [Accepted: 10/03/2023] [Indexed: 10/16/2023]
Abstract
Primary cilia on neural stem/progenitor cells (NSPCs) play an important role in determining cell fate, although the regulatory mechanisms involved in the ciliogenesis remain largely unknown. In this study, we analyzed the effect of the leukemia inhibitory factor (LIF) for the primary cilia in immortalized human NSPCs. LIF withdrawal elongated the primary cilia length, whereas the addition of LIF shortened it. Microarray gene expression analysis revealed that differentially expressed genes (DEGs) associated with LIF treatment were related with the multiple cytokine signaling pathways. Among the DEGs, C-C motif chemokine 2 (CCL2) had the highest ranking and its increase in the protein concentration in the NSPCs-conditioned medium after the LIF treatment was confirmed by ELISA. Interestingly, we found that CCL2 was a negative regulator of cilium length, and LIF-induced shortening of primary cilia was antagonized by CCL2-specific antibody, suggesting that LIF could influence cilia length via upregulating CCL2. The shortening effect of LIF and CCL2 on primary cilia was also observed in SH-SY5Y cells. The results of the study suggested that the LIF-CCL2 axis may well be a regulator of NSPCs and its primary cilia length, which could affect multiple cellular processes, including NSPC proliferation and differentiation.
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Affiliation(s)
- Hisashi Takahashi
- Department of Pathology and Applied Neurobiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Takahiro Fujimoto
- Department of Pathology and Applied Neurobiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Takeshi Yaoi
- Department of Pathology and Applied Neurobiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Shinji Fushiki
- Department of Pathology and Applied Neurobiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Kyoko Itoh
- Department of Pathology and Applied Neurobiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
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Tabuchi A, Ihara D. Regulation of Dendritic Synaptic Morphology and Transcription by the SRF Cofactor MKL/MRTF. Front Mol Neurosci 2021; 14:767842. [PMID: 34795561 PMCID: PMC8593110 DOI: 10.3389/fnmol.2021.767842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/11/2021] [Indexed: 12/12/2022] Open
Abstract
Accumulating evidence suggests that the serum response factor (SRF) cofactor megakaryoblastic leukemia (MKL)/myocardin-related transcription factor (MRTF) has critical roles in many physiological and pathological processes in various cell types. MKL/MRTF molecules comprise MKL1/MRTFA and MKL2/MRTFB, which possess actin-binding motifs at the N-terminus, and SRF-binding domains and a transcriptional activation domain (TAD) at the C-terminus. Several studies have reported that, in association with actin rearrangement, MKL/MRTF translocates from the cytoplasm to the nucleus, where it regulates SRF-mediated gene expression and controls cell motility. Therefore, it is important to elucidate the roles of MKL/MRTF in the nervous system with regard to its structural and functional regulation by extracellular stimuli. We demonstrated that MKL/MRTF is highly expressed in the brain, especially the synapses, and is involved in dendritic complexity and dendritic spine maturation. In addition to the positive regulation of dendritic complexity, we identified several MKL/MRTF isoforms that negatively regulate dendritic complexity in cortical neurons. We found that the MKL/MRTF isoforms were expressed differentially during brain development and the impacts of these isoforms on the immediate early genes including Arc/Arg3.1, were different. Here, we review the roles of MKL/MRTF in the nervous system, with a special focus on the MKL/MRTF-mediated fine-tuning of neuronal morphology and gene transcription. In the concluding remarks, we briefly discuss the future perspectives and the possible involvement of MKL/MRTF in neurological disorders such as schizophrenia and autism spectrum disorder.
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Affiliation(s)
- Akiko Tabuchi
- Laboratory of Molecular Neurobiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Daisuke Ihara
- Laboratory of Molecular Neurobiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
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