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Campbell T, Hawsawi O, Henderson V, Dike P, Hwang BJ, Liadi Y, White EZ, Zou J, Wang G, Zhang Q, Bowen N, Scott D, Hinton CV, Odero-Marah V. Novel roles for HMGA2 isoforms in regulating oxidative stress and sensitizing to RSL3-Induced ferroptosis in prostate cancer cells. Heliyon 2023; 9:e14810. [PMID: 37113783 PMCID: PMC10126861 DOI: 10.1016/j.heliyon.2023.e14810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/09/2023] [Accepted: 03/17/2023] [Indexed: 04/29/2023] Open
Abstract
Oxidative stress is increased in several cancers including prostate cancer, and is currently being exploited in cancer therapy to induce ferroptosis, a novel nonapoptotic form of cell death. High mobility group A2 (HMGA2), a non-histone protein up-regulated in several cancers, can be truncated due to chromosomal rearrangement or alternative splicing of HMGA2 gene. The purpose of this study is to investigate the role of wild-type vs. truncated HMGA2 in prostate cancer (PCa). We analyzed the expression of wild-type vs. truncated HMGA2 and showed that prostate cancer patient tissue and some cell lines expressed increasing amounts of both wild-type and truncated HMGA2 with increasing tumor grade, compared to normal epithelial cells. RNA-Seq analysis of LNCaP prostate cancer cells stably overexpressing wild-type HMGA2 (HMGA2-WT), truncated HMGA2 (HMGA2-TR) or empty vector (Neo) control revealed that HMGA2-TR cells exhibited higher oxidative stress compared to HMGA2-WT or Neo control cells, which was also confirmed by analysis of basal reactive oxygen species (ROS) levels using 2', 7'-dichlorofluorescin diacetate (DCFDA) dye, the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) and NADP/NADPH using metabolomics. This was associated with increased sensitivity to RAS-selective lethal 3 (RSL3)-induced ferroptosis that could be antagonized by ferrostatin-1. Additionally, proteomic and immunoprecipitation analyses showed that cytoplasmic HMGA2 protein interacted with Ras GTPase-activating protein-binding protein 1 (G3BP1), a cytoplasmic stress granule protein that responds to oxidative stress, and that G3BP1 transient knockdown increased sensitivity to ferroptosis even further. Endogenous knockdown of HMGA2 or G3BP1 in PC3 cells reduced proliferation which was reversed by ferrostatin-1. In conclusion, we show a novel role for HMGA2 in oxidative stress, particularly the truncated HMGA2, which may be a therapeutic target for ferroptosis-mediated prostate cancer therapy.
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Affiliation(s)
- Taaliah Campbell
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Ohuod Hawsawi
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Veronica Henderson
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Precious Dike
- Center for Urban Health Disparities Research and Innovation, Department of Biology, Morgan State University, Baltimore, MD, 21251, USA
| | - Bor-Jang Hwang
- Center for Urban Health Disparities Research and Innovation, Department of Biology, Morgan State University, Baltimore, MD, 21251, USA
| | - Yusuf Liadi
- Center for Urban Health Disparities Research and Innovation, Department of Biology, Morgan State University, Baltimore, MD, 21251, USA
| | - ElShaddai Z. White
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Jin Zou
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - GuangDi Wang
- Department of Chemistry, Xavier University, New Orleans, LA, 70125, USA
| | - Qiang Zhang
- Department of Chemistry, Xavier University, New Orleans, LA, 70125, USA
| | - Nathan Bowen
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Derrick Scott
- Department of Biological Sciences, Delaware State University, Dover, DE, 19901, USA
| | - Cimona V. Hinton
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, USA
| | - Valerie Odero-Marah
- Center for Urban Health Disparities Research and Innovation, Department of Biology, Morgan State University, Baltimore, MD, 21251, USA
- Corresponding author. Center for Urban Health Disparities Research and Innovation, Department of Biology, Morgan State University, Baltimore, MD, 21251, USA.
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Gupta A, Hwang BJ, Benyamien-Roufaeil D, Jain S, Liu S, Gonzales R, Brown RA, Zalzman M, Lu AL, Lu AL. Mammalian MutY Homolog (MYH or MUTYH) is Critical for Telomere Integrity under Oxidative Stress. OBM Geriat 2022; 6:196. [PMID: 35812693 PMCID: PMC9267527 DOI: 10.21926/obm.geriatr.2202196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Telomeres consist of special features and proteins to protect the ends of each chromosome from deterioration and fusion. The telomeric DNA repeats are highly susceptible to oxidative damage that can accelerate telomere shortening and affect telomere integrity. Several DNA repair factors including MYH/MUTYH DNA glycosylase, its interacting partners Rad9/Rad1/Hus1 checkpoint clamp, and SIRT6 aging regulator, are associated with the telomeres. MYH prevents C:G to A:T mutation by removing adenine mispaired with a frequent oxidative DNA lesion, 8-oxoguanine. Here, we show that hMYH knockout (KO) human HEK-293T cells are more sensitive to H2O2 treatment, have higher levels of DNA strand breaks and shorter telomeres than the control hMYH +/+ cells. SIRT6 foci increase at both the global genome and at telomeric regions in H2O2-treated hMYH +/+ cells. However, in untreated hMYH KO HEK-293T cells, SIRT6 foci only increase at the global genome, but not at the telomeric regions. In addition, the hMYH KO HEK-293T cells have increased extra-chromosomal and intra-chromosomal telomeres compared to the control cells, even in the absence of H2O2 treatment. After H2O2 treatment, the frequency of extra-chromosomal telomeres increased in control HEK-293T cells. Remarkably, in H2O2-treated hMYH KO cells, the frequencies of extra-chromosomal telomeres, intra-chromosomal telomeres, and telomere fusions are further increased. We further found that the sensitivity to H2O2 and shortened telomeres of hMYH KO cells, are restored by expressing wild-type hMYH, and partially rescued by expressing hMYHQ324H mutant (defective in Hus1 interaction only), but not by expressing hMYHV315A mutant (defective in both SIRT6 and Hus1 interactions). Thus, MYH interactions with SIRT6 and Hus1 are critical for maintaining cell viability and telomeric stability. Therefore, the failure to coordinate 8-oxoG repair is detrimental to telomere integrity.
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Affiliation(s)
- Aditi Gupta
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bor-Jang Hwang
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Sara Jain
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sophie Liu
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Rex Gonzales
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert A Brown
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Michal Zalzman
- University of Maryland School of Medicine; The Center for Stem Cell Biology and Regenerative Medicine; Marlene and Stewart Greenbaum Cancer Center, Baltimore, MD 21201, USA
| | - A-Lien Lu
- University of Maryland School of Medicine; Marlene and Stewart Greenbaum Cancer Center, Baltimore, MD, USA
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Anwar MI, Iqbal M, Hwang BJ, Faiyaz M, Mun BS, Janulewicz KA, Noh DY. Ultrafast x-ray absorption near edge spectroscopy of Fe 3O 4 using a laboratory based femtosecond x-ray source. Opt Express 2019; 27:6030-6036. [PMID: 30876196 DOI: 10.1364/oe.27.006030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Abstract
Ultrafast time-resolved x-ray absorption near edge spectroscopy (XANES) experiment was performed on a magnetite (Fe3O4) film using a femtosecond laser plasma x-ray source delivering Bremsstrahlung radiation. Ultrafast temporal evolution of the XANES of Fe3O4 following an excitation by an infra-red (IR) laser pulse was observed in a pump-probe scheme. The Fe K x-ray absorption edge shifts towards low energy upon IR excitation as much as 12 eV, which is mainly attributed to the charge transfer between the Fe ions. The shift in the absorption edge occurred within about 150 fs, typical time of non-thermal electronic redistribution. The charge transfer also causes an ultrafast increase in the IR transmission in the similar time scale.
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Abstract
Melanoma patients respond poorly to chemotherapies because they acquire drug resistance. Therapies that can overcome the resistance to inhibitors of the mutated BRAF protein kinase in melanoma are urgently needed. Chk1 protein kinase is a central component of the DNA damage response and plays a crucial role in controlling cell cycle progression. Analyses indicate that low mRNA expression of Chk1 is significantly associated with good overall survival of melanoma patients. To evaluate the effectiveness of Chk1 inhibitors in melanoma therapy, we have generated BRAF inhibitor (PLX4032 or vemurafenib) resistant melanoma cell lines (A375-PLX-R and WM9-PLX-R) from A375 and WM9, respectively. We observe that AKT (protein kinase B) is constitutively activated in A375-PLX-R, but not in WM9-PLX-R cells, suggesting that these cells develop resistance to PLX4032 through different mechanisms. We show that a potent and specific inhibitor of Chk1 (PF477736) is effective in reducing cell viability and colony formation of PLX4032-resistant cells. Even more impressively, PF477736 triggers PLX4032-resistant melanoma cells to regain sensitivity to the PLX4032. Mouse xenograft studies show that treating A375-PLX-R derived tumors with combined PLX4032 and PF477736 significantly reduce tumor growth. Combined treatments with PLX4032 and PF477736 reduce the levels of total Chk1 protein and alter Chk1 phosphorylation at several sites in both PLX4032 sensitive and resistant melanoma cells. Combinatorial treatments with PLX4032 and PF477736 to melanoma cells substantially induce DNA damage and cell death. Our results suggest that Chk1 inhibitors may provide new therapy options for melanoma patients.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Gautam Adhikary
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Richard L Eckert
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA.,Department of Dermatology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Reproductive Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.,University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
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Hwang BJ, Jin J, Gao Y, Shi G, Madabushi A, Yan A, Guan X, Zalzman M, Nakajima S, Lan L, Lu AL. SIRT6 protein deacetylase interacts with MYH DNA glycosylase, APE1 endonuclease, and Rad9-Rad1-Hus1 checkpoint clamp. BMC Mol Biol 2015; 16:12. [PMID: 26063178 PMCID: PMC4464616 DOI: 10.1186/s12867-015-0041-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 05/29/2015] [Indexed: 02/07/2023] Open
Abstract
Background SIRT6, a member of the NAD+-dependent histone/protein deacetylase family, regulates genomic stability, metabolism, and lifespan. MYH glycosylase and APE1 are two base excision repair (BER) enzymes involved in mutation avoidance from oxidative DNA damage. Rad9–Rad1–Hus1 (9–1–1) checkpoint clamp promotes cell cycle checkpoint signaling and DNA repair. BER is coordinated with the checkpoint machinery and requires chromatin remodeling for efficient repair. SIRT6 is involved in DNA double-strand break repair and has been implicated in BER. Here we investigate the direct physical and functional interactions between SIRT6 and BER enzymes. Results We show that SIRT6 interacts with and stimulates MYH glycosylase and APE1. In addition, SIRT6 interacts with the 9-1-1 checkpoint clamp. These interactions are enhanced following oxidative stress. The interdomain connector of MYH is important for interactions with SIRT6, APE1, and 9–1–1. Mutagenesis studies indicate that SIRT6, APE1, and Hus1 bind overlapping but different sequence motifs on MYH. However, there is no competition of APE1, Hus1, or SIRT6 binding to MYH. Rather, one MYH partner enhances the association of the other two partners to MYH. Moreover, APE1 and Hus1 act together to stabilize the MYH/SIRT6 complex. Within human cells, MYH and SIRT6 are efficiently recruited to confined oxidative DNA damage sites within transcriptionally active chromatin, but not within repressive chromatin. In addition, Myh foci induced by oxidative stress and Sirt6 depletion are frequently localized on mouse telomeres. Conclusions Although SIRT6, APE1, and 9-1-1 bind to the interdomain connector of MYH, they do not compete for MYH association. Our findings indicate that SIRT6 forms a complex with MYH, APE1, and 9-1-1 to maintain genomic and telomeric integrity in mammalian cells. Electronic supplementary material The online version of this article (doi:10.1186/s12867-015-0041-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA.
| | - Jin Jin
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA.
| | - Ying Gao
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. .,School of Medicine, Tsinghua University, No.1 Tsinghua Yuan, Haidian District, Beijing, 100084, China.
| | - Guoli Shi
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. .,University of Maryland School of Nursing, 655 West Lombard Street, Baltimore, MD, 21201, USA.
| | - Amrita Madabushi
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. .,Department of Natural and Physical Sciences, Life Sciences Institute, Baltimore City Community College, 801 West Baltimore Street, Baltimore, MD, 21201, USA.
| | - Austin Yan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA.
| | - Xin Guan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA.
| | - Michal Zalzman
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. .,Department of Otorhinolaryngology-Head and Neck Surgery, University of Maryland School of Medicine, 16 South Eutaw Street, Baltimore, MD, 21201, USA.
| | - Satoshi Nakajima
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. .,Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA.
| | - Li Lan
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA. .,Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA.
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA. .,Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD, 21201, USA.
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6
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Hwang BJ, Jin J, Gunther R, Madabushi A, Shi G, Wilson GM, Lu AL. Association of the Rad9-Rad1-Hus1 checkpoint clamp with MYH DNA glycosylase and DNA. DNA Repair (Amst) 2015; 31:80-90. [PMID: 26021743 DOI: 10.1016/j.dnarep.2015.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 05/04/2015] [Accepted: 05/08/2015] [Indexed: 12/18/2022]
Abstract
Cell cycle checkpoints provide surveillance mechanisms to activate the DNA damage response, thus preserving genomic integrity. The heterotrimeric Rad9-Rad1-Hus1 (9-1-1) clamp is a DNA damage response sensor and can be loaded onto DNA. 9-1-1 is involved in base excision repair (BER) by interacting with nearly every enzyme in BER. Here, we show that individual 9-1-1 components play distinct roles in BER directed by MYH DNA glycosylase. Analyses of Hus1 deletion mutants revealed that the interdomain connecting loop (residues 134-155) is a key determinant of MYH binding. Both the N-(residues 1-146) and C-terminal (residues 147-280) halves of Hus1, which share structural similarity, can interact with and stimulate MYH. The Hus1(K136A) mutant retains physical interaction with MYH but cannot stimulate MYH glycosylase activity. The N-terminal domain, but not the C-terminal half of Hus1 can also bind DNA with moderate affinity. Intact Rad9 expressed in bacteria binds to and stimulates MYH weakly. However, Rad9(1-266) (C-terminal truncated Rad9) can stimulate MYH activity and bind DNA with high affinity, close to that displayed by heterotrimeric 9(1-266)-1-1 complexes. Conversely, Rad1 has minimal roles in stimulating MYH activity or binding to DNA. Finally, we show that preferential recruitment of 9(1-266)-1-1 to 5'-recessed DNA substrates is an intrinsic property of this complex and is dependent on complex formation. Together, our findings provide a mechanistic rationale for unique contributions by individual 9-1-1 subunits to MYH-directed BER based on subunit asymmetry in protein-protein interactions and DNA binding events.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Jin Jin
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Randall Gunther
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Amrita Madabushi
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Department of Natural and Physical Sciences, Life Sciences Institute; Baltimore City Community College, Baltimore, MD 21201, United States
| | - Guoli Shi
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; University of Maryland School of Nursing, Baltimore, MD 21201, United States
| | - Gerald M Wilson
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States.
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7
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Lim PX, Patel DR, Poisson KE, Basuita M, Tsai C, Lyndaker AM, Hwang BJ, Lu AL, Weiss RS. Genome Protection by the 9-1-1 Complex Subunit HUS1 Requires Clamp Formation, DNA Contacts, and ATR Signaling-independent Effector Functions. J Biol Chem 2015; 290:14826-40. [PMID: 25911100 DOI: 10.1074/jbc.m114.630640] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Indexed: 01/30/2023] Open
Abstract
The RAD9A-HUS1-RAD1 (9-1-1) complex is a heterotrimeric clamp that promotes checkpoint signaling and repair at DNA damage sites. In this study, we elucidated HUS1 functional residues that drive clamp assembly, DNA interactions, and downstream effector functions. First, we mapped a HUS1-RAD9A interface residue that was critical for 9-1-1 assembly and DNA loading. Next, we identified multiple positively charged residues in the inner ring of HUS1 that were crucial for genotoxin-induced 9-1-1 chromatin localization and ATR signaling. Finally, we found two hydrophobic pockets on the HUS1 outer surface that were important for cell survival after DNA damage. Interestingly, these pockets were not required for 9-1-1 chromatin localization or ATR-mediated CHK1 activation but were necessary for interactions between HUS1 and its binding partner MYH, suggesting that they serve as interaction domains for the recruitment and coordination of downstream effectors at damage sites. Together, these results indicate that, once properly loaded onto damaged DNA, the 9-1-1 complex executes multiple, separable functions that promote genome maintenance.
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Affiliation(s)
- Pei Xin Lim
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Darshil R Patel
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Kelsey E Poisson
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Manpreet Basuita
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Charlton Tsai
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Amy M Lyndaker
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
| | - Bor-Jang Hwang
- the Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - A-Lien Lu
- the Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Robert S Weiss
- From the Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853 and
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Bhalla K, Liu WJ, Thompson K, Anders L, Devarakonda S, Dewi R, Buckley S, Hwang BJ, Polster B, Dorsey SG, Sun Y, Sicinski P, Girnun GD. Cyclin D1 represses gluconeogenesis via inhibition of the transcriptional coactivator PGC1α. Diabetes 2014; 63:3266-78. [PMID: 24947365 PMCID: PMC4392904 DOI: 10.2337/db13-1283] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hepatic gluconeogenesis is crucial to maintain normal blood glucose during periods of nutrient deprivation. Gluconeogenesis is controlled at multiple levels by a variety of signal transduction and transcriptional pathways. However, dysregulation of these pathways leads to hyperglycemia and type 2 diabetes. While the effects of various signaling pathways on gluconeogenesis are well established, the downstream signaling events repressing gluconeogenic gene expression are not as well understood. The cell-cycle regulator cyclin D1 is expressed in the liver, despite the liver being a quiescent tissue. The most well-studied function of cyclin D1 is activation of cyclin-dependent kinase 4 (CDK4), promoting progression of the cell cycle. We show here a novel role for cyclin D1 as a regulator of gluconeogenic and oxidative phosphorylation (OxPhos) gene expression. In mice, fasting decreases liver cyclin D1 expression, while refeeding induces cyclin D1 expression. Inhibition of CDK4 enhances the gluconeogenic gene expression, whereas cyclin D1-mediated activation of CDK4 represses the gluconeogenic gene-expression program in vitro and in vivo. Importantly, we show that cyclin D1 represses gluconeogenesis and OxPhos in part via inhibition of peroxisome proliferator-activated receptor γ coactivator-1α (PGC1α) activity in a CDK4-dependent manner. Indeed, we demonstrate that PGC1α is novel cyclin D1/CDK4 substrate. These studies reveal a novel role for cyclin D1 on metabolism via PGC1α and reveal a potential link between cell-cycle regulation and metabolic control of glucose homeostasis.
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Affiliation(s)
- Kavita Bhalla
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | - Wan-Ju Liu
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | - Keyata Thompson
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | | | | | - Ruby Dewi
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | - Stephanie Buckley
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | - Bor-Jang Hwang
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD
| | - Brian Polster
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD
| | - Susan G Dorsey
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD Department of Organizational Systems and Adult Health, University of Maryland School of Nursing, Baltimore, MD
| | - Yezhou Sun
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD
| | - Piotr Sicinski
- Dana-Farber Cancer Institute, Boston, MA Department of Genetics, Harvard Medical School, Boston, MA
| | - Geoffrey D Girnun
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD Department of Pathology, Stony Brook School of Medicine, Stony Brook, NY
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9
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Hwang BJ, Madabushi A, Jin J, Lin SYS, Lu AL. Histone/protein deacetylase SIRT1 is an anticancer therapeutic target. Am J Cancer Res 2014; 4:211-221. [PMID: 24959376 PMCID: PMC4065402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 04/23/2014] [Indexed: 06/03/2023] Open
Abstract
SIRT1, a member of the NAD(+)-dependent histone/protein deacetylase family, is involved in chromatin remodeling, DNA repair, and stress response and is a potential drug target. 5-fluorouracil (FU) and the SN1-type DNA methylating agent temozolomide (TMZ) are anticancer agents. In this study, we demonstrate that sirt1 knockout mouse embryonic fibroblast cells are more sensitive to FU and DNA methylating agents than normal cells. Based on these findings, the chemotherapy efficacy of SIRT1 inhibitors in combination with FU or TMZ were tested with human breast cancer cells. We found that treatments combining SIRT1 inhibitors with FU or TMZ show synergistic reduction of cell viability and colony formation of breast cancer cells. Thus, inhibition of SIRT1 activity provides a novel anticancer strategy.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - Amrita Madabushi
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimore, MD 21201, USA
- Current address: Department of Natural & Physical Sciences, Life Sciences Institute; Baltimore City Community CollegeBaltimore, MD 21201
| | - Jin Jin
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - Shiou-Yuh S Lin
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimore, MD 21201, USA
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimore, MD 21201, USA
- University of Maryland Greenebaum Cancer CenterBaltimore, MD 21201, USA
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Jin J, Hwang BJ, Chang PW, Toth EA, Lu AL. Interaction of apurinic/apyrimidinic endonuclease 2 (Apn2) with Myh1 DNA glycosylase in fission yeast. DNA Repair (Amst) 2014; 15:1-10. [PMID: 24559510 PMCID: PMC3967872 DOI: 10.1016/j.dnarep.2014.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 12/27/2013] [Accepted: 01/06/2014] [Indexed: 12/29/2022]
Abstract
Oxidative DNA damage is repaired primarily by the base excision repair (BER) pathway in a process initiated by removal of base lesions or mismatched bases by DNA glycosylases. MutY homolog (MYH, MUTYH, or Myh1) is a DNA glycosylase which excises adenine paired with the oxidative lesion 8-oxo-7,8-dihydroguanine (8-oxoG, or G°), thus reducing G:C to T:A mutations. The resulting apurinic/apyrimidinic (AP) site is processed by an AP-endonuclease or a bifunctional glycosylase/lyase. We show here that the major Schizosaccharomyces pombe AP endonuclease, Apn2, binds to the inter-domain connector located between the N- and C-terminal domains of Myh1. This Myh1 inter-domain connector also interacts with the Hus1 subunit of the Rad9-Rad1-Hus1 checkpoint clamp. Mutagenesis studies indicate that Apn2 and Hus1 bind overlapping but different sequence motifs on Myh1. Mutation on I(261) of Myh1 reduces its interaction with Hus1, but only slightly attenuates its interaction with Apn2. However, E(262) of Myh1 is a key determinant for both Apn2 and Hus1 interactions. Like human APE1, Apn2 has 3'-phosphodiesterase activity. However, unlike hAPE1, Apn2 has a weak AP endonuclease activity which cleaves the AP sites generated by Myh1 glycosylase. Functionally, Apn2 stimulates Myh1 glycosylase activity and Apn2 phosphodiesterase activity is stimulated by Myh1. The cross stimulation of Myh1 and Apn2 enzymatic activities is dependent on their physical interaction. Thus, Myh1 and Apn2 constitute an initial BER complex.
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Affiliation(s)
- Jin Jin
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Po-Wen Chang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eric A Toth
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Center for Biomolecular Therapeutics, University of Maryland School of Medicine, Rockville, MD 20850, USA
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Hwang BJ, Shi G, Lu AL. Mammalian MutY homolog (MYH or MUTYH) protects cells from oxidative DNA damage. DNA Repair (Amst) 2013; 13:10-21. [PMID: 24315136 DOI: 10.1016/j.dnarep.2013.10.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 10/22/2013] [Accepted: 10/30/2013] [Indexed: 11/18/2022]
Abstract
MutY DNA glycosylase homologs (MYH or MUTYH) reduce G:C to T:A mutations by removing misincorporated adenines or 2-hydroxyadenines paired with guanine or 8-oxo-7,8-dihydroguanine (8-oxo-G). Mutations in the human MYH (hMYH) gene are associated with the colorectal cancer predisposition syndrome MYH-associated polyposis. To examine the function of MYH in human cells, we regulated MYH gene expression by knockdown or overproduction. MYH knockdown human HeLa cells are more sensitive to the killing effects of H2O2 than the control cells. In addition, hMYH knockdown cells have altered cell morphology, display enhanced susceptibility to apoptosis, and have altered DNA signaling activation in response to oxidative stress. The cell cycle progression of hMYH knockdown cells is also different from that of the control cells following oxidative stress. Moreover, hMYH knockdown cells contain higher levels of 8-oxo-G lesions than the control cells following H2O2 treatment. Although MYH does not directly remove 8-oxo-G, MYH may generate favorable substrates for other repair enzymes. Overexpression of mouse Myh (mMyh) in human mismatch repair defective HCT15 cells makes the cells more resistant to killing and refractory to apoptosis by oxidative stress than the cells transfected with vector. In conclusion, MYH is a vital DNA repair enzyme that protects cells from oxidative DNA damage and is critical for a proper cellular response to DNA damage.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Gouli Shi
- University of Maryland Greenebaum Cancer Center, Baltimore, MD 21201, United States
| | - A-Lien Lu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States; University of Maryland Greenebaum Cancer Center, Baltimore, MD 21201, United States.
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12
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Luncsford PJ, Manvilla BA, Patterson DN, Malik SS, Jin J, Hwang BJ, Gunther R, Kalvakolanu S, Lipinski LJ, Yuan W, Lu W, Drohat AC, Lu AL, Toth EA. Coordination of MYH DNA glycosylase and APE1 endonuclease activities via physical interactions. DNA Repair (Amst) 2013; 12:1043-52. [PMID: 24209961 DOI: 10.1016/j.dnarep.2013.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/30/2013] [Accepted: 09/20/2013] [Indexed: 11/26/2022]
Abstract
MutY homologue (MYH) is a DNA glycosylase which excises adenine paired with the oxidative lesion 7,8-dihydro-8-oxoguanine (8-oxoG, or G(o)) during base excision repair (BER). Base excision by MYH results in an apurinic/apyrimidinic (AP) site in the DNA where the DNA sugar-phosphate backbone remains intact. A key feature of MYH activity is its physical interaction and coordination with AP endonuclease I (APE1), which subsequently nicks DNA 5' to the AP site. Because AP sites are mutagenic and cytotoxic, they must be processed by APE1 immediately after the action of MYH glycosylase. Our recent reports show that the interdomain connector (IDC) of human MYH (hMYH) maintains interactions with hAPE1 and the human checkpoint clamp Rad9-Rad1-Hus1 (9-1-1) complex. In this study, we used NMR chemical shift perturbation experiments to determine hMYH-binding site on hAPE1. Chemical shift perturbations indicate that the hMYH IDC peptide binds to the DNA-binding site of hAPE1 and an additional site which is distal to the APE1 DNA-binding interface. In these two binding sites, N212 and Q137 of hAPE1 are key mediators of the MYH/APE1 interaction. Intriguingly, despite the fact that hHus1 and hAPE1 both interact with the MYH IDC, hHus1 does not compete with hAPE1 for binding to hMYH. Rather, hHus1 stabilizes the hMYH/hAPE1 complex both in vitro and in cells. This is consistent with a common theme in BER, namely that the assembly of protein-DNA complexes enhances repair by efficiently coordinating multiple enzymatic steps while simultaneously minimizing the release of harmful repair intermediates.
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Affiliation(s)
- Paz J Luncsford
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, United States
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13
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Liu S, Gonzalez J, Hwang BJ, Steinberg ML. Induction of cyclin D1 by arsenite and UVB-irradiation in human keratinocytes. J Health Care Poor Underserved 2012; 22:110-21. [PMID: 22102309 DOI: 10.1353/hpu.2011.0158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Arsenic is an environmental pollutant with carcinogenic properties that is found in many regions of the world but that poses a health risk primarily in economically disadvantaged areas. In these areas, arsenic ingestion affects various tissues, especially skin in which it acts as a comutagen with the ultraviolet component of solar radiation. Both epidemiological and experimental evidence indicates that arsenic and ultraviolet radiation act on signaling pathways that effect the expression of cyclin D1. We have previously employed an in vitro model system of human epidermal keratinocytes to study the effects of submicromolar concentrations of sodium arsenite on cyclin D1 expression. Here, we employed this system to demonstrate concordant cyclin D1-related induction profiles of ultraviolet B radiation and arsenite using cDNA microarray analysis. We also show that both of these agents act epigenetically to bring about demethylation of the cyclin D1 promoter.
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Affiliation(s)
- Suqing Liu
- Department of Chemistry, The City College of New York, Convent Avenue and 138th Street, New York, NY 10031, USA
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14
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Hwang BJ, Kuttamperoor F, Wu J, Steinberg ML. Spectrum of mitochondrial DNA deletions within the common deletion region induced by low levels of UVB irradiation of human keratinocytes in vitro. Gene 2009; 440:23-7. [PMID: 19345726 PMCID: PMC2706008 DOI: 10.1016/j.gene.2009.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 03/25/2009] [Accepted: 03/26/2009] [Indexed: 11/30/2022]
Abstract
We show that a single low-dose exposure of human epidermal keratinocytes (NHEK) to an FS20 light source in vitro can induce the formation of mitochondrial DNA deletions in a PCR detection assay. We used primer sets specifically designed to exclude amplification of segments containing the common deletion, but which could detect possibly lower abundance deletions generated within the same region of the mitochondrial genome. We characterized eight novel deletions of which six were generated from cut sites within, or adjacent to, short direct repeats. Two deletions involved cut sites in inverted tetrameric repeats; one of these also involved an insertion.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Chemistry, The City College of the City University of New York, New York, NY 10031
| | - Francis Kuttamperoor
- Department of Chemistry, The City College of the City University of New York, New York, NY 10031
| | - Julia Wu
- Department of Chemistry, The City College of the City University of New York, New York, NY 10031
| | - Mark L. Steinberg
- Department of Chemistry, The City College of the City University of New York, New York, NY 10031
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15
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Steinberg ML, Hubbard K, Utti C, Clas B, Hwang BJ, Hill HZ, Orlow I. Patterns of persistent DNA damage associated with sun exposure and the glutathione S-transferase M1 genotype in melanoma patients. Photochem Photobiol 2009; 85:379-86. [PMID: 19161404 DOI: 10.1111/j.1751-1097.2008.00455.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Solar radiation can lead to changes affecting DNA metabolism resulting in loss of DNA integrity. Skin specimens obtained from melanoma patients treated at the Memorial Sloan-Kettering Cancer Center were used to study patterns of DNA fragmentation using the comet assay and levels of deletions in mitochondrial DNA (mtDNA) using real-time PCR. Skin specimens were classified according to the glutathione S-transferase M1 (GSTM1) genotype (either wild type [WT] or null) and patient sunburn history. GSTM1 null individuals with a sunburn history showed increased levels of both DNA fragmentation by comet assays and mtDNA deletions relative to GSTM1 WT patients with little or no sunburn history. Microarray analyses identified a number of genes whose expression was upregulated >or=5-fold in cells from GSTM1-null patients or from those reporting histories of sunburn. These genes encoded small molecule transporters, various growth factor/chemokine receptors, transcription factors and tumor suppressors. Of 17 genes directly involved in DNA repair, three DNA ligases were highly upregulated while the RAD23 UV excision repair gene and the Growth Arrest and DNA Damage gene (GADD45) were downregulated. These findings support the idea that exposure to solar radiation early in life may induce long-term cellular changes that lead to persistent DNA damage and altered patterns of gene expression.
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Affiliation(s)
- Mark L Steinberg
- Department of Chemistry, The City College of the City University of New York, New York, NY, USA.
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16
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Steinberg ML, Hwang BJ, Tang L, Shah MA. E-cadherin gene alterations in gastric cancers in different ethnic populations. Ethn Dis 2008; 18:S2-74. [PMID: 18646324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
INTRODUCTION A retrospective study of nucleotide sequence alterations in exons 7-9 of the E-cadherin gene and expression of E-cadherin and beta-catenin in gastric tumors from African American, Asian, Causcasian and Hispanic patients was carried out to determine differences potentially related to race/ethnicity in these groups. METHODS Paraffin-embedded tissue sections archived at the Memorial Sloan Kettering Cancer Center were used for immunohistochemical staining of sections for membranous E-cadherin protein and nuclear localization of beta-catenin. DNA from tumor tissue extracted from the paraffin sections was used as template for amplification of the E-cadherin gene exonic regions. RESULTS Sequence analyses of the high-frequency mutation region along E-cadherin exons 7-9 revealed a number sequence alterations in the patient group as a whole, mostly within exon 8. The alterations were mainly single nucleotide insertions, but a palindromic duplication of exon 8 in a Caucasian patient and several extragenic insertions in a Hispanic and an African American patient were also found. Nuclear localization of beta-catenin was correlated with inactivating sequence alterations in three patients. CONCLUSIONS Exon 8 was found to display the most extensive alterations in all the groups studied. As a group, the most extensive sequence alterations were found in tumors from Caucasian patients. A finding of potential significance as a biomarker related to ethnicity was a C insertion at nt 76,598 found independently in two African American patients.
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Affiliation(s)
- Mark L Steinberg
- Department of Chemistry, The City College of New York, Convent Ave and 138th St, New York, NY 10031, USA.
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17
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Hwang BJ, Utti C, Steinberg M. Induction of cyclin D1 by submicromolar concentrations of arsenite in human epidermal keratinocytes. Toxicol Appl Pharmacol 2006; 217:161-7. [PMID: 17005224 DOI: 10.1016/j.taap.2006.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 08/08/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
Arsenic is a prevalent environmental carcinogen but arsenic is not directly mutagenic and the mechanism by which arsenite brings about oncogenic transformation is poorly understood. To gain insight into the oncogenic properties of arsenic, we studied the expression of cyclin D1 in cultured human epidermal keratinocytes treated with submicromolar concentrations of sodium arsenite. Arsenite at concentrations between 200 and 800 nM over a 3-day period brought about an increase in cell growth rate. Uptake of the vital stain, neutral red, arsenite at 200 and 400 nM concentrations brought about a parallel increase in cell viability over the same treatment period. Analysis of cell cycle parameters by flow cytometry showed that the growth stimulation was accompanied by a concomitant shift from the G1 into the S/G2 cell cycle compartment in the arsenite-treated cells. Real-time PCR analysis of cyclin D1 transcription showed that there was an induction of more than three-fold in cells exposed to 400 nM arsenite for 3 days. Quantitation of cyclin D levels in Western blots showed that arsenite treatment caused a time-dependent induction of cyclin D proteins representing an induction of about 2.0-fold after a 7 day treatment period. Electrophoretic mobility shift assays (EMSA) showed that arsenite also stimulated binding of the transcription factors, AP1 and CREBP to their respective binding motifs within 3 days. This supports a mechanism of oncogenesis based on persistent upregulation of D type cyclins leading to a concomitant loss of G1/S checkpoint control.
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Affiliation(s)
- Bor-Jang Hwang
- Department of Chemistry, The City College of the City University of New York, Convent Avenue and 138th Street, New York, NY 10031, USA
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18
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Ji F, Pierre Z, Liu S, Hwang BJ, Hill HZ, Hubbard K, Steinberg M. Novel mitochondrial deletions in human epithelial cells irradiated with an FS20 ultraviolet light source in vitro. J Photochem Photobiol A Chem 2006. [DOI: 10.1016/j.jphotochem.2006.04.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Qabar A, Nelson M, Guzman J, Corun C, Hwang BJ, Steinberg M. Modulation of sulfur mustard induced cell death in human epidermal keratinocytes using IL-10 and TNF-α. J Biochem Mol Toxicol 2005; 19:213-25. [PMID: 16173061 DOI: 10.1002/jbt.20089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We compared the effects of overexpressing a tightly regulated anti-inflammatory cytokine, interleukin 10 (IL-10), and the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) on sulfur mustard induced cytotoxicity in human epidermal keratinocytes. Both cytokines were overexpressed when compared with the cells transfected with the empty vector as determined by quantitative ELISA. Cells overexpressing interleukin 10 suppressed the pro-inflammatory cytokines interleukin 8 and interleukin 6 following exposure to 50-300 microM sulfur mustard. These cells exhibited delayed onset of sulfur mustard induced cell death. On the other hand, cells overexpressing tumor necrosis factor alpha induced a sustained elevation in both interleukin 6 and 8 expression following exposure to 50-300 microM sulfur mustard. These cells were sensitized to the effects of sulfur mustard that resulted in an increased sulfur mustard induced cell death. Normal human epidermal keratinocytes treated with sulfur mustard exhibited elevated levels of tumor necrosis factor alpha expression and increased activity of nuclear factor kappa B. Gene array data indicated that cells overexpressing interleukin 10 induced several genes that are involved in growth promotion and cell-fate determination. We, therefore, identify IL-10 and TNF-alpha signal transduction pathways and their components as possible candidates for early therapeutic intervention against sulfur mustard induced cell injury.
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Affiliation(s)
- Aziz Qabar
- US Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, MD 21010, USA.
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20
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Affiliation(s)
- B J Hwang
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
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21
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Hwang BJ, Tsai YW, Lee JF, Borthen P, Strehblow HH. In situ EXAFS investigation of carbon-supported Pt clusters under potential control. J Synchrotron Radiat 2001; 8:484-486. [PMID: 11512823 DOI: 10.1107/s0909049500019671] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 02/01/2001] [Indexed: 05/23/2023]
Abstract
The transformation of carbon supported Pt clusters under potential control in 1M HClO4 solution was investigated by in-situ X-ray absorption spectroscopy measurements. Both XANES and EXAFS data are used to show the structure evolution of the Pt clusters at various potentials. It showed that the white line area and the edge energy increase with the applied potential in the range 0.1-1.5V. The coordination number of oxygen and platinum on the Pt/C electrode increases and decreases, respectively, with the applied potential. It is found that the size of Pt cluster does not grow during the electrode fabrication. However, the crystallization of Pt cluster occurs during the potential cycling.
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Affiliation(s)
- B J Hwang
- Dept. of Chem. Eng., NTUST, Taipei, Taiwan, R.O.C.
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22
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Bansal A, Singer JH, Hwang BJ, Xu W, Beaudet A, Feller MB. Mice lacking specific nicotinic acetylcholine receptor subunits exhibit dramatically altered spontaneous activity patterns and reveal a limited role for retinal waves in forming ON and OFF circuits in the inner retina. J Neurosci 2000; 20:7672-81. [PMID: 11027228 PMCID: PMC6772851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Before phototransduction, spontaneous activity in the developing mammalian retina is required for the appropriate patterning of retinothalamic connections, and there is growing evidence that this activity influences the development of circuits within the retina itself. We demonstrate here that the neural substrate that generates waves in the mouse retina develops through three distinct stages. First, between embryonic day 16 and birth [postnatal day 0 (P0)], we observed both large, propagating waves inhibited by nicotinic acetylcholine receptor (nAChR) antagonists and small clusters of cells displaying nonpropagating, correlated calcium increases that were independent of nAChR activation. Second, between P0 and P11, we observed only larger propagating waves that were abolished by toxins specific to alpha3 and beta2 subunit-containing nAChRs. Third, between P11 and P14 (eye opening) we observed propagating activity that was abolished by ionotropic glutamate receptor antagonists. The time course of this developmental shift was dramatically altered in retinas from mice lacking the beta2 nAChR subunit or the beta2 and beta4 subunits. These retinas exhibited a novel circuit at P0, no spontaneous correlated activity between P1 and P8, and the premature induction at P8 of an ionotropic glutamate receptor-based circuit. Retinas from postnatal mice lacking the alpha3 nAChR subunit exhibited spontaneous, correlated activity patterns that were similar to those observed in embryonic wild-type mice. In alpha3-/- and beta2-/- mice, the development and distribution of cholinergic neurons and processes and the density of retinal ganglion cells (RGCs) and the gross segregation of their dendrites into ON and OFF sublaminae were normal. However, the refinement of individual RGC dendrites is delayed. These results indicate that retinal waves mediated by nAChRs are involved in, but not required for, the development of neural circuits that define the ON and OFF sublamina of the inner plexiform layer.
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Affiliation(s)
- A Bansal
- Synapse Formation and Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Howard Hughes Medical Institute-National Institutes of Health Research Scholars Program, Bethesda, Maryland, USA
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Abstract
Herpesviruses can establish a persistent infection in the cells and tissues of their natural hosts and thus may produce diseases due to cytolytic infections. We have isolated a herpesvirus from a bovine vascular endothelial cell culture after continuous subculturing. Typical cytopathic changes were observed in bovine endothelial cell cultures 2 days after inoculation of the virus. The virus had an icosahedral nucleocapsid of 100-150 nm in diameter and an envelope. The sequences of some DNA fragments of the virus were highly homologous to those of the bovine herpesvirus type 4 (BHV-4) strains. The DNA restriction maps of the virus and the reference strains of BHV-4, DN 599 and Movar 33/63 were very similar but not identical. Therefore, the newly isolated virus has been designated Taiwan strain. The presence of BHV-4 DNA in apparently normal bovine endothelial cell cultures was shown by Southern blot hybridization with the BamHI fragment of the newly isolated BHV-4 and was further confirmed by digestion of the DNA with BamHI plus AccI. In conclusion, we have demonstrated that BHV-4 persisted in the bovine endothelial cell cultures and continuous subcultures could lead to the production of infectious viral particles.
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Affiliation(s)
- T M Lin
- Department of Medical Technology, National Cheng Kung University, Tainan, Taiwan, ROC
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24
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Affiliation(s)
- B J Hwang
- Department of Medicine, Stanford University Medical Center, CA, USA
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Hwang BJ, Kim Y, Kim HB, Hwang HJ, Kim JH, Lee HS. Analysis of Corynebacterium glutamicum methionine biosynthetic pathway: isolation and analysis of metB encoding cystathionine gamma-synthase. Mol Cells 1999; 9:300-8. [PMID: 10420990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
The metB gene encoding cystathionine y-synthase, the second enzyme of methionine biosynthetic pathway, was isolated from a pSL109-based Corynebacterium glutamicum gene library via complementation of an Escherichia coli metB mutant. A DNA-sequence analysis of the cloned DNA identified an open-reading frame of 1161 bp which encodes a protein with the molecular weight of 41,655 comprising of 386 amino acids. The putative protein product showed good amino acid-sequence homology to its counterpart in other organisms. Introduction of a plasmid carrying the cloned metB into the C. glutamicum resulted in a 10-fold increase in cystathionine gamma-synthase activities, demonstrating the identity of the cloned gene. The C. glutamicum metB mutant which was generated by the site-specific integration of the cloned DNA into its chromosome did not lose the ability to grow on glucose minimal medium lacking supplemental methionine. The growth rate of the mutant strain was also comparable to that of the parental strain. These data indicate that, in addition to the transsulfuration pathway, other methionine biosynthetic pathways may be present in C. glutamicum.
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Affiliation(s)
- B J Hwang
- Graduate School of Biotechnology, Korea University, Seoul
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26
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Hwang BJ, Ford JM, Hanawalt PC, Chu G. Expression of the p48 xeroderma pigmentosum gene is p53-dependent and is involved in global genomic repair. Proc Natl Acad Sci U S A 1999; 96:424-8. [PMID: 9892649 PMCID: PMC15152 DOI: 10.1073/pnas.96.2.424] [Citation(s) in RCA: 410] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In human cells, efficient global genomic repair of DNA damage induced by ultraviolet radiation requires the p53 tumor suppressor, but the mechanism has been unclear. The p48 gene is required for expression of an ultraviolet radiation-damaged DNA binding activity and is disrupted by mutations in the subset of xeroderma pigmentosum group E cells that lack this activity. Here, we show that p48 mRNA levels strongly depend on basal p53 expression and increase further after DNA damage in a p53-dependent manner. Furthermore, like p53(-/-) cells, xeroderma pigmentosum group E cells are deficient in global genomic repair. These results identify p48 as the link between p53 and the nucleotide excision repair apparatus.
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Affiliation(s)
- B J Hwang
- Departments of Medicine and Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5115, USA
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27
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Abstract
Polymicrogyria, a developmental cortical malformation associated with epilepsy, can be modeled in rats with a transcortical freeze lesion on the day of birth (P0) or P1. We have used field potential recordings to characterize the incidence, propagation patterns, and distribution of epileptiform activity in slices from rats with experimental microgyri. Interictal-like epileptiform activity was evoked in slices from 85% of freeze-lesioned rats aged P12-P118. These data show age-specific properties of epileptogenesis, including: a delay in onset, a decrease in the incidence of epileptiform activity in rats >P40 that was specific to those lesioned on P0 as opposed to P1, and a shift in the likely site of initiation to areas further from the microgyrus in mature animals. Several observations suggest that the area adjacent to the microgyrus, which appears histologically normal in Nissl stains, contains the necessary epileptogenic neuronal circuits: 1) in 78% of slices, epileptiform activity could be evoked only from a focal zone adjacent to the microgyrus (paramicrogyral zone) and not within the microgyrus proper; 2) epileptiform activity consistently originated from a particular site within this paramicrogyral zone, independent of the location of the stimulating electrode, suggesting that the generator is outside of the microgyrus; 3) evoked epileptiform activities in the paramicrogyral cortex were unaltered after separation of this zone from the microgyrus with a transcortical cut; and 4) the short-latency graded field potential evoked in the paramicrogyral zone contained an additional negativity not seen in control slices. The epileptiform activity was blocked reversibly by N-methyl--aspartate receptor antagonists in slices from mature as well as immature freeze-lesioned rats. These results suggest that aberrant synaptic connectivity develops in rat cortex surrounding the microgyrus and produces a focal epileptogenic zone whose capacity to generate epileptiform activities does not depend on connections with the malformation itself. We hypothesize that afferents, originating from cortical and extracortical sites, lose their targets in the region of the malformation and make appropriate laminar contacts in the cortex adjacent to the malformation, creating an overabundance of excitatory input to this cortical zone. Increased excitatory feedback onto specific cortical elements may be one factor involved in epileptogenesis in this model of a cortical malformation.
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Affiliation(s)
- K M Jacobs
- Department of Neurology and Neurological Sciences, Stanford University Medical Center, Stanford, California 94305, USA
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Hwang BJ, Toering S, Francke U, Chu G. p48 Activates a UV-damaged-DNA binding factor and is defective in xeroderma pigmentosum group E cells that lack binding activity. Mol Cell Biol 1998; 18:4391-9. [PMID: 9632823 PMCID: PMC109023 DOI: 10.1128/mcb.18.7.4391] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A subset of xeroderma pigmentosum (XP) group E cells lack a factor that binds to DNA damaged by UV radiation. This factor can be purified to homogeneity as p125, a 125-kDa polypeptide. However, when cDNA encoding p125 is translated in vitro, only a small fraction binds to UV-damaged DNA, suggesting that a second factor is required for the activation of p125. We discovered that most hamster cell lines expressed inactive p125, which was activated in somatic cell hybrids containing human chromosome region 11p11.2-11cen. This region excluded p125 but included p48, which encodes a 48-kDa polypeptide known to copurify with p125 under some conditions. Expression of human p48 activated p125 binding in hamster cells and increased p125 binding in human cells. No such effects were observed from expression of p48 containing single amino acid substitutions from XP group E cells that lacked binding activity, demonstrating that the p48 gene is defective in those cells. Activation of p125 occurred by a "hit-and-run" mechanism, since the presence of p48 was not required for subsequent binding. Nevertheless, p48 was capable of forming a complex with p125 either bound to UV-damaged DNA or in free solution. It is notable that hamster cells fail to efficiently repair cyclobutane pyrimidine dimers in nontranscribed DNA and fail to express p48, which contains a WD motif with homology to proteins that reorganize chromatin. We propose that p48 plays a role in repairing lesions that would otherwise remain inaccessible in nontranscribed chromatin.
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Affiliation(s)
- B J Hwang
- Departments of Medicine and Biochemistry, Stanford University School of Medicine, Stanford, California 94305, USA
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29
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Abstract
We have developed an elution-digestion-sequencing (EDS) method, which yields the internal amino acid sequence of partially purified proteins. The overall yield for the method was greater than 60%. The method yielded peptide peaks that could be sequenced on HPLC for all tested proteins with masses from 45 to 200.10(3) and yielded internal amino acid sequence information when as little as 10 pmol of partially purified protein was used as the starting material. The EDS method was extremely reliable and gave sequence information for each of 25 proteins tested, including high-molecular-mass proteins (M(r) > 100.10(3)) that were difficult to sequence by other methods.
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Affiliation(s)
- B J Hwang
- Department of Medicine, Stanford University Medical Center, CA 94305, USA
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30
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Affiliation(s)
- B J Hwang
- Department of Medicine, Stanford University Medical Center 94305, USA
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31
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Abstract
XPE binding factor (XPE-BF) is deficient in a subset of patients from xeroderma pigmentosum complementation group E. Binding activity copurifies with a 125 kDa polypeptide (p125) that binds to DNA damaged by ultraviolet (UV) radiation and many other agents. We isolated cDNA encoding a polypeptide with a predicted amino acid sequence that matched the sequences of eleven tryptic peptides derived from digestion of XPE-BF purified from human placenta. In vitro transcription and translation of the cDNA yielded a polypeptide of 125 kDa that bound specifically to UV-damaged DNA. Therefore the cDNA encodes either all or the major component of XPE-BF.
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Affiliation(s)
- B J Hwang
- Department of Medicine, Stanford University Medical Center, CA 94305, USA
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32
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Abstract
Xeroderma pigmentosum (XP) is an inherited disease characterized by defective repair of DNA damaged by ultraviolet (UV) radiation or agents that produce bulky DNA adducts. Human cells contain a factor that is deficient in a subset of patients from XP complementation group E and binds to DNA damaged by UV, cisplatin, or denaturation. This factor, XPE binding factor (XPE-BF), was purified to near homogeneity. The denatured protein migrated as a 125-kDa polypeptide on SDS-PAGE, and the native protein migrated primarily as a monomer on gel filtration and glycerol gradient sedimentation. Sedimentation revealed major peak in binding activity at 6.8 S, corresponding to the monomeric form, and a minor peak at 14.5 S, suggesting a homodimeric form. Binding activity was dependent on unmodified cysteine residues, stimulated by magnesium, and inhibited by zinc. Binding to UV-damaged nucleotides was 500,000-fold greater than for intact nucleotides, explaining how a molecule with an abundance of only 1-2 molecules per megabase can survey the genome for damaged DNA. Binding required a minimal DNA substrate of between 16 and 26 bp, as determined by a novel "shoe size" assay. Consistent with its previously noted versatility, XPE-BF bound to some cyclobutane pyrimidine dimers and at least one other UV-induced lesion. However, it may not bind to a subset of cyclobutane dimers, likely including the thymine dimer. These findings may explain the relatively mild phenotype of XP group E and suggest the existence of at least one other binding protein involved in the XP repair pathway.
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Affiliation(s)
- B J Hwang
- Department of Medicine, Stanford University Medical Center, California 94305
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33
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Abstract
Two soluble serine proteases Do and So from Escherichia coli were found to distinctively cleave the purified, 39 kDa Ada protein into fragments with sizes of 12-31 kDa. Protease So appears to generate a C-terminal 19 kDa polypeptide, similarly to OmpT protease. In addition, the purified 19 kDa C-terminal half of Ada protein can be further processed mainly to an 18 kDa fragment by protease So and to a 12 kDa by protease Do. These results suggest that proteases Do and So are involved in endogenous cleavage of Ada protein, which may play a role in down-regulating the adaptive response to alkylating agents.
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Affiliation(s)
- C S Lee
- Department of Zoology, College of Natural Sciences, Seoul National University, Korea
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34
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Hwang BJ, Woo KM, Goldberg AL, Chung CH. Protease Ti, a new ATP-dependent protease in Escherichia coli, contains protein-activated ATPase and proteolytic functions in distinct subunits. J Biol Chem 1988; 263:8727-34. [PMID: 2967816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In addition to protease La (the lon gene product), Escherichia coli contains another ATP-dependent protease, Ti. This enzyme (approximately 340 kDa) is composed of two components, both of which are required for proteolysis. Both have been purified to homogeneity by conventional procedures using [3H]casein as the substrate. The ATP-stabilized component, A, has a subunit molecular weight of 80,000 upon gel electrophoresis in the presence of sodium dodecyl sulfate, but it behaves as a dimer (140 kDa) upon gel filtration. Component P, which is relatively heat stable, is inactivated by diisopropyl fluorophosphate and can be labeled with [3H] diisopropyl fluorophosphate. It has a subunit size of 23 kDa, but the isolated component behaves as a complex (260 kDa) of 10-12 subunits. The isoelectric point of component A is 7.0 and that of P is 8.2, and their amino acid compositions differ considerably. The purified enzyme has an ATPase activity that is stimulated 2-4-fold by casein and other protein substrates but not by nonhydrolyzed proteins. Component A also shows ATPase activity which can be stimulated by casein. Addition of component P (which lacks ATPase activity) inhibits basal ATP hydrolysis by A and makes this ATPase more responsive to casein. Although component P contains the serine active site for proteolysis, it shows no proteolytic activity in the absence of component A, Mg2+, and ATP or dATP. Other nucleoside triphosphates are not hydrolyzed and do not support proteolysis. Protease Ti has a Km for ATP of 210 microM for hydrolysis of both casein and ATP. Casein increases the Vmax for ATP without affecting the Km. A Mg2+ concentration of 5 mM is necessary for half-maximal rates of ATP and casein hydrolysis. Ca2+ and Mn2+ partially support these activities. Thus, protease Ti shares many unusual properties with protease La (e.g. coupled ATP and protein hydrolysis and protein-activated ATPase), but these functions in protease Ti are associated with distinct subunits that modify each other's activities.
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Affiliation(s)
- B J Hwang
- Department of Zoology, College of Natural Science, Seoul National University, Korea
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35
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Hwang BJ, Woo KM, Goldberg AL, Chung CH. Protease Ti, a new ATP-dependent protease in Escherichia coli, contains protein-activated ATPase and proteolytic functions in distinct subunits. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68366-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Hwang BJ, Park WJ, Chung CH, Goldberg AL. Escherichia coli contains a soluble ATP-dependent protease (Ti) distinct from protease La. Proc Natl Acad Sci U S A 1987; 84:5550-4. [PMID: 3303028 PMCID: PMC298900 DOI: 10.1073/pnas.84.16.5550] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The energy requirement for protein breakdown in Escherichia coli has generally been attributed to the ATP-dependence of protease La, the lon gene product. We have partially purified another ATP-dependent protease from lon-cells that lack protease La (as shown by immunoblotting). This enzyme hydrolyzes [3H]methyl-casein to acid-soluble products in the presence of ATP and Mg2+. ATP hydrolysis appears necessary for proteolytic activity. Since this enzyme is inhibited by diisopropyl fluorophosphate, it appears to be a serine protease, but it also contains essential thiol residues. We propose to name this enzyme protease Ti. It differs from protease La in nucleotide specificity, inhibitor sensitivity, and subunit composition. On gel filtration, protease Ti has an apparent molecular weight of 370,000. It can be fractionated by phosphocellulose chromatography or by DEAE chromatography into two components with apparent molecular weights of 260,000 and 140,000. When separated, they do not show proteolytic activity. One of these components, by itself, has ATPase activity and is labile in the absence of ATP. The other contains the diisopropyl fluorophosphate-sensitive proteolytic site. These results and the similar findings of Katayama-Fujimura et al. [Katayama-Fujimura, Y., Gottesman, S. & Maurizi, M. R. (1987) J. Biol. Chem. 262, 4477-4485] indicate that E. coli contains two ATP-hydrolyzing proteases, which differ in many biochemical features and probably in their physiological roles.
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