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Guo X, Peng K, He Y, Xue L. Mechanistic regulation of FOXO transcription factors in the nucleus. Biochim Biophys Acta Rev Cancer 2024; 1879:189083. [PMID: 38309444 DOI: 10.1016/j.bbcan.2024.189083] [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: 10/18/2023] [Revised: 01/28/2024] [Accepted: 01/31/2024] [Indexed: 02/05/2024]
Abstract
FOXO proteins represent evolutionarily conserved transcription factors (TFs) that play critical roles in responding to various physiological signals or pathological stimuli, either through transcription-dependent or -independent mechanisms. Dysfunction of these proteins have been implicated in numerous diseases, including cancer. Although the regulation of FOXO TFs shuttling between the cytoplasm and the nucleus has been extensively studied and reviewed, there's still a lack of a comprehensive review focusing on the intricate interactions between FOXO, DNA, and cofactors in the regulation of gene expression. In this review, we aim to summarize recent advances and provide a detailed understanding of the mechanism underlying FOXO proteins binding to target DNA. Additionally, we will discuss the challenges associated with pharmacological approaches in modulating FOXO function, and explore the dynamic association between TF, DNA, and RNA on chromatin. This review will contribute to a better understanding of mechanistic regulations of eukaryotic TFs within the nucleus.
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Affiliation(s)
- Xiaowei Guo
- The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China; The Engineering Research Center of Reproduction and Translational Medicine of Hunan Province, Changsha, China.
| | - Kai Peng
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Yanwen He
- Changsha Stomatological Hospital, Hunan University of Chinese Medicine, Changsha, Hunan, China
| | - Lei Xue
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, Shanghai, China.
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Guo X, Wu C, Pan Y, Zhu X, Peng K, Ma X, Xue L. Mechanistic insights and implications of FOXO-SNAI interplay. Bioessays 2022; 44:e2200070. [PMID: 35832016 DOI: 10.1002/bies.202200070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/29/2021] [Accepted: 07/05/2022] [Indexed: 11/06/2022]
Abstract
Autophagy promotes both health and disease, depending on tissue types and genetic contexts, yet the regulatory mechanism remain incompletely understood. Our recent publication has uncovered a coherent FOXO-SNAI feed-forward loop in autophagy, which is evolutionarily conserved from Drosophila to human. In addition, it's revealed that DNA binding plays a critical role in intracellular localization of nucleocytoplasmic shuttling proteins. Based on these findings, herein we further integrate mechanistic insights of FOXO-SNAI regulatory interplay in autophagy and unravel the potential link of FOXO-induced autophagy with SNAI in diseases. Besides, the generality of DNA-retention mechanism on transcription factor nuclear localization is illustrated with wide-ranging discussion, and more functions potentially regulated by FOXO-SNAI feedforward loop are provided. Elucidation of these unsolved paradigms will expand the understanding of FOXO-SNAI interplay and facilitate the development of new therapeutics targeting FOXO-SNAI axis in diseases.
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Affiliation(s)
- Xiaowei Guo
- School of Medicine, Hunan Normal University, Changsha, Hunan, China.,Institute of Intervention Vessel, Shanghai 10th People's Hospital, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Chenxi Wu
- College of Traditional Chinese Medicine, North China University of Science and Technology, Tangshan, Hebei, China
| | - Yu Pan
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Xiaojie Zhu
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Kai Peng
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Xianjue Ma
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
| | - Lei Xue
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, School of Life Science and Technology, Tongji University, Shanghai, China.,Zhuhai Precision Medical Center, Zhuhai People's Hospital, Zhuhai Hospital Affiliated with Jinan University, Zhuhai, Guangdong, China
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Kappert L, Ruzicka P, Kutikhin A, De La Torre C, Fischer A, Hecker M, Arnold C, Korff T. Loss of Nfat5 promotes lipid accumulation in vascular smooth muscle cells. FASEB J 2021; 35:e21831. [PMID: 34383982 DOI: 10.1096/fj.202100682r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/09/2021] [Accepted: 07/19/2021] [Indexed: 01/19/2023]
Abstract
The nuclear factor of activated T-cells 5 (NFAT5) is a transcriptional regulator of macrophage activation and T-cell development, which controls stabilizing responses of cells to hypertonic and biomechanical stress. In this study, we detected NFAT5 in the media layer of arteries adjacent to human arteriosclerotic plaques and analyzed its role in vascular smooth muscle cells (VSMCs) known to contribute to arteriosclerosis through the uptake of lipids and transformation into foam cells. Exposure of both human and mouse VSMCs to cholesterol stimulated the nuclear translocation of NFAT5 and increased the expression of the ATP-binding cassette transporter Abca1, required to regulate cholesterol efflux from cells. Loss of Nfat5 promoted cholesterol accumulation in these cells and inhibited the expression of genes involved in the management of oxidative stress or lipid handling, such as Sod1, Plin2, Fabp3, and Ppard. The functional relevance of these observations was subsequently investigated in mice fed a high-fat diet upon induction of a smooth muscle cell-specific genetic ablation of Nfat5 (Nfat5(SMC)-/- ). Under these conditions, Nfat5(SMC)-/- but not Nfat5fl/fl mice developed small, focal lipid-rich lesions in the aorta after 14 and 25 weeks, which were formed by intracellular lipid droplets deposited in the sub-intimal VSMCs layer. While known for being activated by external stimuli, NFAT5 was found to mediate the expression of VSMC genes associated with the handling of lipids in response to a cholesterol-rich environment. Failure of this protective function may promote the formation of lipid-laden arterial VSMCs and pro-atherogenic vascular responses.
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Affiliation(s)
- Lena Kappert
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Philipp Ruzicka
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Anton Kutikhin
- Division of Experimental Medicine, Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russian Federation
| | - Carolina De La Torre
- Center of Medical Research, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Andreas Fischer
- Division Vascular Signaling and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Department of Internal Medicine I, Heidelberg University, Heidelberg, Germany.,European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Markus Hecker
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Caroline Arnold
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Thomas Korff
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.,European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
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NFAT5, which protects against hypertonicity, is activated by that stress via structuring of its intrinsically disordered domain. Proc Natl Acad Sci U S A 2020; 117:20292-20297. [PMID: 32747529 DOI: 10.1073/pnas.1911680117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nuclear Factor of Activated T cells 5 (NFAT5) is a transcription factor (TF) that mediates protection from adverse effects of hypertonicity by increasing transcription of genes, including those that lead to cellular accumulation of protective organic osmolytes. NFAT5 has three intrinsically ordered (ID) activation domains (ADs). Using the NFAT5 N-terminal domain (NTD), which contains AD1, as a model, we demonstrate by biophysical methods that the NTD senses osmolytes and hypertonicity, resulting in stabilization of its ID regions. In the presence of sufficient NaCl or osmolytes, trehalose and sorbitol, the NFAT5 NTD undergoes a disorder-to-order shift, adopting higher average secondary and tertiary structure. Thus, NFAT5 is activated by the stress that it protects against. In its salt and/or osmolyte-induced more ordered conformation, the NTD interacts with several proteins, including HMGI-C, which is known to protect against apoptosis. These findings raise the possibility that the increased intracellular ionic strength and elevated osmolytes caused by hypertonicity activate and stabilize NFAT5.
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Izumi Y, Burg MB, Ferraris JD. 14-3-3-β and -{varepsilon} contribute to activation of the osmoprotective transcription factor NFAT5 by increasing its protein abundance and its transactivating activity. Physiol Rep 2014; 2:e12000. [PMID: 24771694 PMCID: PMC4001879 DOI: 10.14814/phy2.12000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Having previously found that high NaCl causes rapid exit of 14‐3‐3 isoforms from the nucleus, we used siRNA‐mediated knockdown to test whether 14‐3‐3s contribute to the high NaCl‐induced increase in the activity of the osmoprotective transcription factor NFAT5. We find that, when NaCl is elevated, knockdown of 14‐3‐3‐β and/or 14‐3‐3‐ε decreases NFAT5 transcriptional activity, as assayed both by luciferase reporter and by the mRNA abundance of the NFAT5 target genes aldose reductase and the sodium‐ and chloride‐dependent betaine transporter, BGT1. Knockdown of other 14‐3‐3 isoforms does not significantly affect NFAT5 activity. 14‐3‐3‐β and/or 14‐3‐3‐ε do not act by affecting the nuclear localization of NFAT5, but by at least two other mechanisms: (1) 14‐3‐3‐β and 14‐3‐3‐ε increase protein abundance of NFAT5 and (2) they increase NFAT5 transactivating activity. When NaCl is elevated, knockdown of 14‐3‐3‐β and/or 14‐3‐3‐ε reduces the protein abundance of NFAT5, as measured by Western blot, without affecting the level of NFAT5 mRNA, and the knockdown also decreases NFAT5 transactivating activity, as measured by luciferase reporter. The 14‐3‐3s increase NFAT5 protein, not by increasing its translation, but by decreasing the rate at which it is degraded, as measured by cycloheximide chase. It is not clear at this point whether the 14‐3‐3s affect NFAT5 directly or indirectly through their effects on other proteins that signal activation of NFAT5. e12000 When NaCl is elevated, knockdown of 14‐3‐3‐β and/or 14‐3‐3‐ε reduces the protein abundance of NFAT5, as measured by Western blot, without affecting the level of NFAT5 mRNA, and the knockdown also decreases NFAT5 transactivating activity, as measured by luciferase reporter. The 14‐3‐3s increase NFAT5 protein, not by increasing its translation, but by decreasing the rate at which it is degraded, as measured by cycloheximide chase.
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Affiliation(s)
- Yuichiro Izumi
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Li M, Shoemaker BA, Thangudu RR, Ferraris JD, Burg MB, Panchenko AR. Mutations in DNA-binding loop of NFAT5 transcription factor produce unique outcomes on protein-DNA binding and dynamics. J Phys Chem B 2013; 117:13226-34. [PMID: 23734591 PMCID: PMC3807822 DOI: 10.1021/jp403310a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The nuclear factor of activated T
cells 5 (NFAT5 or TonEBP) is
a Rel family transcriptional activator and is activated by hypertonic
conditions. Several studies point to a possible connection between
nuclear translocation and DNA binding; however, the mechanism of NFAT5
nuclear translocation and the effect of DNA binding on retaining NFAT5
in the nucleus are largely unknown. Recent experiments showed that
different mutations introduced in the DNA-binding loop and dimerization
interface were important for DNA binding and some of them decreased
the nuclear–cytoplasm ratio of NFAT5. To understand the mechanisms
of these mutations, we model their effect on protein dynamics and
DNA binding. We show that the NFAT5 complex without DNA is much more
flexible than the complex with DNA. Moreover, DNA binding considerably
stabilizes the overall dimeric complex and the NFAT5 dimer is only
marginally stable in the absence of DNA. Two sets of NFAT5 mutations
from the same DNA-binding loop are found to have different mechanisms
of specific and nonspecific binding to DNA. The R217A/E223A/R226A
(R293A/E299A/R302A using isoform c numbering) mutant is characterized
by significantly compromised binding to DNA and higher complex flexibility.
On the contrary, the T222D (T298D in isoform c) mutation, a potential
phosphomimetic mutation, makes the overall complex more rigid and
does not significantly affect the DNA binding. Therefore, the reduced
nuclear–cytoplasm ratio of NFAT5 can be attributed to reduced
binding to DNA for the triple mutant, while the T222D mutant suggests
an additional mechanism at work.
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Affiliation(s)
- Minghui Li
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health , Bethesda, MD, United States
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Cheung CY, Ko BC. NFAT5 in cellular adaptation to hypertonic stress - regulations and functional significance. J Mol Signal 2013; 8:5. [PMID: 23618372 PMCID: PMC3655004 DOI: 10.1186/1750-2187-8-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/11/2013] [Indexed: 12/22/2022] Open
Abstract
The Nuclear Factor of Activated T Cells-5 (NFAT5), also known as OREBP or TonEBP, is a member of the nuclear factors of the activated T cells family of transcription factors. It is also the only known tonicity-regulated transcription factor in mammals. NFAT5 was initially known for its role in the hypertonic kidney inner medulla for orchestrating a genetic program to restore the cellular homeostasis. Emerging evidence, however, suggests that NFAT5 might play a more diverse functional role, including a pivotal role in blood pressure regulation and the development of autoimmune diseases. Despite the growing significance of NFAT5 in physiology and diseases, our understanding of how its activity is regulated remains very limited. Furthermore, how changes in tonicities are converted into functional outputs via NFAT5 remains elusive. Therefore, this review aims to summarize our current knowledge on the functional roles of NFAT5 in osmotic stress adaptation and the signaling pathways that regulate its activity.
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Affiliation(s)
- Chris Yk Cheung
- Department of Anatomical and Cellular Pathology, and The State Key Laboratory in Oncology in South China, The Chinese University of Hong Kong, The Prince of Wales Hospital, Rm 38019, Clinical Sciences Building, Shatin, Hong Kong, China.
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A Single Amino Acid Substitution in the Renal Betaine/GABA Transporter Prevents Trafficking to the Plasma Membrane. ACTA ACUST UNITED AC 2013. [DOI: 10.1155/2013/598321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
One response to hypertonic stress in the renal medulla and MDCK cells is the upregulation of betaine transporter (BGT1) synthesis, followed by trafficking to the plasma membrane (PM) and an increase in betaine transport. Upregulation of BGT1 was enhanced by inhibitors of phosphatases PP1 and PP2A and was attenuated by inhibitors of protein kinase C, suggesting an important role for phosphorylation reactions. This was tested using mutants of BGT1 tagged with EGFP. The PM trafficking motifs of BGT1 reside near the C terminus, and truncation at lysine560 resulted in a protein that remained intracellular during hypertonic stress. This K560Δ mutant colocalized with endoplasmic reticulum (ER). Substitution of alanine at Thr40, a putative phosphorylation site, also prevented trafficking to the PM during hypertonic stress. Live-cell imaging showed that T40A was not retained in the ER and colocalized with markers for Golgi and endosomes. In contrast, substitution of aspartate or glutamate at Thr40, to mimic phosphorylation, restored normal trafficking to the PM. HEK293 cells transfected with K560Δ or T40A mutants had 10% of the GABA transport activity of native BGT1, but normal transport activity was restored in cells expressing T40E. Normal BGT1 trafficking likely requires phosphorylation at Thr40 in addition to C-terminal motifs.
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