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Karaosmanoğlu C, Yıldız SH, Akdoğan M, Erdoğan MÖ. Association of CUL4B with the pathogenesis of age-related cataract. Int Ophthalmol 2024; 44:288. [PMID: 38937308 DOI: 10.1007/s10792-024-03011-1] [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: 01/11/2022] [Accepted: 10/29/2023] [Indexed: 06/29/2024]
Abstract
PURPOSE Age-related cataract (ARC) is the most common cause of visual impairment and blindness in older adults. However, the role of CUL4B in the ARC remains unclear. Therefore, we investigated CUL4B expression and its effects on apoptosis. MATERIALS AND METHODS CUL4B expression levels were detected by a quantitative real-time polymerase chain reaction from the anterior lens capsules of patients with ARC and HLE-B3 cells treated with different concentrations of H2O2. CUL4B expression was silenced by siRNA transfection to evaluate apoptosis. CUL4B and apoptotic proteins B cell lymphoma 2 (Bcl-2), myeloid cell leukemia 1 (Mcl-1), caspase-3, cleaved caspase-3, Bax, Bak, and Bid were assessed using western blot analysis. Apoptosis was monitored using the TUNEL assay. RESULTS CUL4B expression was downregulated in the anterior lens capsules (P < 0.0001) and H2O2-treated HLE-B3 cells (P = 0.0405). CUL4B protein levels were significantly lower in 100 µmol/L (P = 0.0012) and 200 µmol/L (P = 0.0041) H2O2-treated HLE-B3 cells than in the untreated cells. CUL4B expression was significantly knocked down at the mRNA (P = 0.0043) and protein levels (P = 0.0002) in HLE-B3 cells. Bcl-2 (P = 0.0199), Mcl-1 (P = 0.0042), and caspase-3 (P = 0.0142) were significantly downregulated, whereas cleaved caspase-3 (P = 0.0089) and Bak (P = 0.009) were significantly upregulated in the knockdown group. The TUNEL assay showed a greater induction of apoptosis. CONCLUSIONS CUL4B downregulation promotes the apoptosis of lens epithelial cells. Our study may help in understanding the role of CUL4B in ARC pathogenesis.
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Affiliation(s)
- Cem Karaosmanoğlu
- Department of Medical Genetics, Faculty of Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey.
| | - Saliha Handan Yıldız
- Department of Medical Genetics, Faculty of Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey
| | - Müberra Akdoğan
- Department of Ophthalmology, Faculty of Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey
| | - Müjgan Özdemir Erdoğan
- Department of Medical Genetics, Faculty of Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey
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The roles of mouse double minute 2 (MDM2) oncoprotein in ocular diseases: A review. Exp Eye Res 2022; 217:108910. [PMID: 34998788 DOI: 10.1016/j.exer.2021.108910] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/03/2021] [Accepted: 12/21/2021] [Indexed: 12/19/2022]
Abstract
Mouse double minute 2 (MDM2), an E3 ubiquitin ligase and the primary negative regulator of the tumor suppressor p53, cooperates with its structural homolog MDM4/MDMX to control intracellular p53 level. In turn, overexpression of p53 upregulates and forms an autoregulatory feedback loop with MDM2. The MDM2-p53 axis plays a pivotal role in modulating cell cycle control and apoptosis. MDM2 itself is regulated by the PI3K-AKT and RB-E2F-ARF pathways. While amplification of the MDM2 gene or overexpression of MDM2 (due to MDM2 SNP T309G, for instance) is associated with various malignancies, numerous studies have shown that MDM2/p53 alterations may also play a part in the pathogenetic process of certain ocular disorders (Fig. 1). These include cancers (retinoblastoma, uveal melanoma), fibrocellular proliferative diseases (proliferative vitreoretinopathy, pterygium), neovascular diseases, degenerative diseases (cataract, primary open-angle glaucoma, age-related macular degeneration) and infectious/inflammatory diseases (trachoma, uveitis). In addition, MDM2 is implicated in retinogenesis and regeneration after optic nerve injury. Anti-MDM2 therapy has shown potential as a novel approach to treating these diseases. Despite major safety concerns, there are high expectations for the clinical value of reformative MDM2 inhibitors. This review summarizes important findings about the role of MDM2 in ocular pathologies and provides an overview of recent advances in treating these diseases with anti-MDM2 therapies.
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Wang Z, Su D, Sun Z, Liu S, Sun L, Li Q, Guan L, Liu Y, Ma X, Hu S. MDM2 phosphorylation mediates H 2O 2-induced lens epithelial cells apoptosis and age-related cataract. Biochem Biophys Res Commun 2020; 528:112-119. [PMID: 32471716 DOI: 10.1016/j.bbrc.2020.05.060] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/09/2020] [Indexed: 12/14/2022]
Abstract
Lens epithelial cells (LECs) apoptosis induced by oxidative stress is a major factor in age-related-cataract (ARC) pathogenesis, but there are still many blind nodes in this progress. This study aimed to investigate the effects of MDM2 phosphorylation in ARC and H2O2-induced lens epithelial cells apoptosis. Our results confirmed that the levels of p-MDM2 (Ser166) and p-MDM2 (Ser186) in the anterior lens capsules of human cataracts were reduced compared to that in normal capsules. Similarly, in naturally aging cataract mice, the level of MDM2 phosphorylation also decreased. Oxidative stress-induced apoptosis model was constructed by cultivating HLE-B3 cells with 200 μM H2O2. It was confirmed that MDM2 could regulate lens epithelial cell apoptosis, and MDM2 inhibitors could partly inhibited AKT's role in suppressing apoptosis induced by H2O2. Besides, we examed the decreased level of p-AKT(Ser473) in apoptosis of lens epithelial cells and ARC. Our study revealed that MDM2 phosphorylation mediated H2O2-induced lens epithelial cells apoptosis and ARC, which could provide new ideas for the clinical treatment of ARC.
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Affiliation(s)
- Zhongying Wang
- Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China
| | - Dongmei Su
- Department of Genetics, National Research Institute for Family Planning, Health Department, Beijing, 100081, China; Graduate School, Peking Union Medical College, Beijing, 100081, China
| | - Zhaoyi Sun
- Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China
| | - Shanhe Liu
- Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China
| | - Lei Sun
- Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China
| | - Qian Li
- Department of Genetics, National Research Institute for Family Planning, Health Department, Beijing, 100081, China
| | - Lina Guan
- Department of Genetics, National Research Institute for Family Planning, Health Department, Beijing, 100081, China
| | - Yong Liu
- Medical Research Center of Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China
| | - Xu Ma
- Department of Genetics, National Research Institute for Family Planning, Health Department, Beijing, 100081, China; Graduate School, Peking Union Medical College, Beijing, 100081, China.
| | - Shanshan Hu
- Hongqi Hospital of Mudanjiang Medical College, Mudanjiang, 157011, Heilongjiang, China.
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Hilliard SA, Li Y, Dixon A, El-Dahr SS. Mdm4 controls ureteric bud branching via regulation of p53 activity. Mech Dev 2020; 163:103616. [PMID: 32464196 DOI: 10.1016/j.mod.2020.103616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 05/19/2020] [Accepted: 05/21/2020] [Indexed: 02/07/2023]
Abstract
The antagonism between Mdm2 and its close homolog Mdm4 (also known as MdmX) and p53 is vital for embryogenesis and organogenesis. Previously, we demonstrated that targeted disruption of Mdm2 in the Hoxb7+ ureteric bud (Ub) lineage, which gives rise to the renal collecting system, causes renal hypodysplasia culminating in perinatal lethality. In this study, we examine the unique role of Mdm4 in establishing the collecting duct system of the murine kidney. Hoxb7Cre driven loss of Mdm4 in the Ub lineage (UbMdm4-/-) disrupts branching morphogenesis and triggers UB cell apoptosis. UbMdm4-/- kidneys exhibit abnormally dilated Ub tips while the medulla is hypoplastic. These structural alterations result in secondary depletion of nephron progenitors and nascent nephrons. As a result, newborn UbMdm4-/- mice have hypo-dysplastic kidneys. Transcriptional profiling revealed downregulation of the Ret-tyrosine kinase pathway components, Gdnf, Wnt11, Sox8, Etv4 and Cxcr4 in the UbMdm4-/- mice relative to controls. Moreover, the expression levels of the canonical Wnt signaling members Axin2 and Wnt9b are downregulated. Mdm4 deletion upregulated p53 activity and p53-target gene expression including Cdkn1a (p21), Gdf15, Ccng1, PERP, and Fas. Germline loss of p53 in UbMdm4-/- mice largely rescues kidney development and terminal differentiation of the collecting duct. We conclude that Mdm4 plays a unique and vital role in Ub branching morphogenesis and collecting system development.
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Affiliation(s)
- Sylvia A Hilliard
- Tulane University School of Medicine, Department of Pediatrics, Section of Pediatric Nephrology, New Orleans, LA 70112, United States of America
| | - Yuwen Li
- Tulane University School of Medicine, Department of Pediatrics, Section of Pediatric Nephrology, New Orleans, LA 70112, United States of America
| | - Angelina Dixon
- Tulane University School of Medicine, Department of Pediatrics, Section of Pediatric Nephrology, New Orleans, LA 70112, United States of America
| | - Samir S El-Dahr
- Tulane University School of Medicine, Department of Pediatrics, Section of Pediatric Nephrology, New Orleans, LA 70112, United States of America.
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Tackmann NR, Zhang Y. Mouse modelling of the MDM2/MDMX-p53 signalling axis. J Mol Cell Biol 2017; 9:34-44. [PMID: 28096294 PMCID: PMC5907827 DOI: 10.1093/jmcb/mjx006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/12/2017] [Indexed: 01/10/2023] Open
Abstract
It is evident that p53 activity is critical for tumour prevention and stress response through its transcriptional activation of genes affecting cellular senescence, apoptosis, cellular metabolism, and DNA repair. The regulation of p53 is highly complex, and MDM2 and MDMX are thought to be critical for deciding the fate of p53, both through inhibitory binding and post-translational modification. Many mouse models have been generated to study the regulation of p53 in vivo, and they have altered our interpretations of how p53 is regulated by MDM2 and MDMX. Although MDM2 is absolutely required for p53 regulation, certain functions are dispensable under unstressed conditions, including the ability of MDM2 to degrade p53. MDMX, on the other hand, may only be required in select situations, like embryogenesis. These models have also clarified how cellular stress signals modify the p53-inhibiting activities of MDM2 and MDMX in vivo. It is clear that more work will need to be performed to further understand the contexts for each of these signals and the requirements of various MDM2 and MDMX functions. Here, we will discuss what we have learned from mouse modelling of MDM2 and MDMX and underscore the ways in which these models could inform future therapies.
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Affiliation(s)
- Nicole R Tackmann
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.,Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Yanping Zhang
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.,Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou 221002, China
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El-Dahr S, Hilliard S, Saifudeen Z. Regulation of kidney development by the Mdm2/Mdm4-p53 axis. J Mol Cell Biol 2017; 9:26-33. [PMID: 28096292 PMCID: PMC5907835 DOI: 10.1093/jmcb/mjx005] [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: 10/12/2016] [Accepted: 01/15/2017] [Indexed: 01/13/2023] Open
Abstract
While p53 activity is required for tumour suppression, unconstrained p53 activity on the other hand is detrimental to the organism, resulting in inappropriate cellular death or proliferation defects. Unimpeded p53 activity is lethal in the developing embryo, underlining the need for maintaining a tight control on p53 activity during this period. The critical role of the negative regulators of p53, Mdm2 and Mdm4, in vertebrate development came to light by fatal disruption of embryogenesis that was observed with Mdm2 and Mdm4 gene deletions in mice. Embryonic lethality was rescued only by superimposing p53 removal. Here we summarize the contribution of the Mdm2/Mdm4–p53 axis that occurs at multiple steps of kidney development. Conditional, cell type-specific deletions reveal distinct functions of these proteins in renal morphogenesis. The severe impact on the renal phenotype from targeted gene deletions underscores the critical role played by the Mdm2/Mdm4–p53 nexus on nephrogenesis, and emphasizes the need to monitor patients with aberrations in this pathway for kidney function defects and associated cardiovascular dysfunction.
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Affiliation(s)
- Samir El-Dahr
- Department of Pediatrics, Section of Pediatric Nephrology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Sylvia Hilliard
- Department of Pediatrics, Section of Pediatric Nephrology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Zubaida Saifudeen
- Department of Pediatrics, Section of Pediatric Nephrology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Zhou X, Cao B, Lu H. Negative auto-regulators trap p53 in their web. J Mol Cell Biol 2017; 9:62-68. [PMID: 28069666 PMCID: PMC5907828 DOI: 10.1093/jmcb/mjx001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/14/2016] [Accepted: 01/06/2017] [Indexed: 01/07/2023] Open
Abstract
The transcriptional factor p53 activates the expression of a myriad of target genes involving a complicated signalling network, resulting in various cellular outcomes, such as growth arrest, senescence, apoptosis, and metabolic changes, and leading to consequent suppression of tumour growth and progression. Because of the profoundly adverse effect of p53 on growth and proliferation of cancer cells, several feedback mechanisms have been employed by the cells to constrain p53 activity. Two major antagonists MDM2 and MDMX (the long forms) are transcriptionally induced by p53, but in return block p53 activity, forming a negative feedback circuit and rendering chemoresistance of several cancer cells. However, they are not alone, as cancer cells also employ other proteins encoded by p53 target genes to inhibit p53 activity at transcriptional, translational, and posttranslational levels. This essay is thus composed to review a recent progress in understanding the mechanisms for how cancer cells hijack the p53 autoregulation by these proteins for their growth advantage and to discuss the clinical implications of these autoregulatory loops.
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Affiliation(s)
- Xiang Zhou
- Fudan University Shanghai Cancer Center and the Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Bo Cao
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Hua Lu
- Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Zhang Y, Zeng SX, Hao Q, Lu H. Monitoring p53 by MDM2 and MDMX is required for endocrine pancreas development and function in a spatio-temporal manner. Dev Biol 2017; 423:34-45. [PMID: 28118981 DOI: 10.1016/j.ydbio.2017.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 02/06/2023]
Abstract
Although p53 is not essential for normal embryonic development, it plays a pivotal role in many biological and pathological processes, including cell fate determination-dependent and independent events and diseases. The expression and activity of p53 largely depend on its two biological inhibitors, MDM2 and MDMX, which have been shown to form a complex in order to tightly control p53 to an undetectable level during early stages of embryonic development. However, more delicate studies using conditional gene-modification mouse models show that MDM2 and MDMX may function separately or synergistically on p53 regulation during later stages of embryonic development and adulthood in a cell and tissue-specific manner. Here, we report the role of the MDM2/MDMX-p53 pathway in pancreatic islet morphogenesis and functional maintenance, using mouse lines with specific deletion of MDM2 or MDMX in pancreatic endocrine progenitor cells. Interestingly, deletion of MDM2 results in defects of embryonic endocrine pancreas development, followed by neonatal hyperglycemia and lethality, by inducing pancreatic progenitor cell apoptosis and inhibiting cell proliferation. However, unlike MDM2-knockout animals, mice lacking MDMX in endocrine progenitor cells develop normally. But, surprisingly, the survival rate of adult MDMX-knockout mice drastically declines compared to control mice, as blockage of neonatal development of endocrine pancreas by inhibition of cell proliferation and subsequent islet dysfunction and hyperglycemia eventually lead to type 1 diabetes-like disease with advanced diabetic nephropathy. As expected, both MDM2 and MDMX deletion-caused pancreatic defects are completely rescued by loss of p53, verifying the crucial role of the MDM2 and/or MDMX in regulating p53 in a spatio-temporal manner during the development, functional maintenance, and related disease progress of endocrine pancreas. Also, our study suggests a possible mouse model of advanced diabetic nephropathy, which is complementary to other established diabetic models and perhaps useful for the development of anti-diabetes therapies.
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Affiliation(s)
- Yiwei Zhang
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA; Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Shelya X Zeng
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA; Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Qian Hao
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Hua Lu
- Department of Biochemistry & Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA; Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA.
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Moyer SM, Larsson CA, Lozano G. Mdm proteins: critical regulators of embry ogenesis and homeostasis. J Mol Cell Biol 2017; 9:mjx004. [PMID: 28093454 PMCID: PMC5439424 DOI: 10.1093/jmcb/mjx004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/13/2016] [Accepted: 01/10/2017] [Indexed: 12/31/2022] Open
Abstract
Mdm2 and Mdm4 are negative regulators of the tumor suppressor p53; hence, this relationship is the focus of many cancer related studies. A multitude of experiments across various developmental stages have been conducted to explore the tissue-specific roles of these proteins in the mouse. When Mdm2 or Mdm4 are deleted in the germline or specific tissues, they display different phenotypic defects, some of which lead to embryonic lethality. Mdm2 loss is often more deleterious than loss of its homolog Mdm4 All tissues experience activation of p53 target genes upon loss of Mdm2 or Mdm4; however, the degree to which the p53 pathway is perturbed is highly tissue-specific and does not correlate to the severity of the morphological phenotypes. Therefore, a need for further understanding of how these proteins regulate p53 activity is warranted, as therapeutic targeting of the p53 pathway is rapidly evolving and gaining attention in the field of cancer research. In this review, we discuss the tissue-specificity of Mdm proteins in regulating p53 and expose the need for investigation at the cell-specific level.
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Affiliation(s)
- Sydney M Moyer
- Department of Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
| | - Connie A Larsson
- Department of Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
| | - Guillermina Lozano
- Department of Genetics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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