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Xu H, Zhang LB, Luo YY, Wang L, Zhang YP, Chen PQ, Ba XY, Han J, Luo H. Synaptotagmins family affect glucose transport in retinal pigment epithelial cells through their ubiquitination-mediated degradation and glucose transporter-1 regulation. World J Diabetes 2024; 15:958-976. [PMID: 38766439 PMCID: PMC11099358 DOI: 10.4239/wjd.v15.i5.958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/22/2024] [Accepted: 03/11/2024] [Indexed: 05/10/2024] Open
Abstract
BACKGROUND Synaptotagmins (SYTs) are a family of 17 membrane transporters that function as calcium ion sensors during the release of Ca2+-dependent neurotransmitters and hormones. However, few studies have reported whether members of the SYT family play a role in glucose uptake in diabetic retinopathy (DR) through Ca2+/glucose transporter-1 (GLUT1) and the possible regulatory mechanism of SYTs. AIM To elucidate the role of the SYT family in the regulation of glucose transport in retinal pigment epithelial cells and explore its potential as a therapeutic target for the clinical management of DR. METHODS DR was induced by streptozotocin in C57BL/6J mice and by high glucose medium in human retinal pigment epithelial cells (ARPE-19). Bioinformatics analysis, reverse transcriptase-polymerase chain reaction, Western blot, flow cytometry, ELISA, HE staining, and TUNEL staining were used for analysis. RESULTS Six differentially expressed proteins (SYT2, SYT3, SYT4, SYT7, SYT11, and SYT13) were found between the DR and control groups, and SYT4 was highly expressed. Hyperglycemia induces SYT4 overexpression, manipulates Ca2+ influx to induce GLUT1 fusion with the plasma membrane, promotes abnormal expression of the glucose transporter GLUT1 and excessive glucose uptake, induces ARPE-19 cell apoptosis, and promotes DR progression. Parkin deficiency inhibits the proteasomal degradation of SYT4 in DR, resulting in SYT4 accumulation and enhanced GLUT1 fusion with the plasma membrane, and these effects were blocked by oe-Parkin treatment. Moreover, dysregulation of the myelin transcription factor 1 (Myt1)-induced transcription of SYT4 in DR further activated the SYT4-mediated stimulus-secretion coupling process, and this process was inhibited in the oe-MYT1-treated group. CONCLUSION Our study reveals the key role of SYT4 in regulating glucose transport in retinal pigment epithelial cells during the pathogenesis of DR and the underlying mechanism and suggests potential therapeutic targets for clinical DR.
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Affiliation(s)
- Hong Xu
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Li-Bo Zhang
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Yi-Yi Luo
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Ling Wang
- Department of Endocrinology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Ye-Pin Zhang
- Department of Pathology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Pei-Qi Chen
- Department of Endocrinology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Xue-Ying Ba
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Jian Han
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Heng Luo
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
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Zhang C, Gu L, Xie H, Liu Y, Huang P, Zhang J, Luo D, Zhang J. Glucose transport, transporters and metabolism in diabetic retinopathy. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166995. [PMID: 38142757 DOI: 10.1016/j.bbadis.2023.166995] [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: 08/02/2023] [Revised: 12/02/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
Diabetic retinopathy (DR) is the most common reason for blindness in working-age individuals globally. Prolonged high blood glucose is a main causative factor for DR development, and glucose transport is prerequisite for the disturbances in DR caused by hyperglycemia. Glucose transport is mediated by its transporters, including the facilitated transporters (glucose transporter, GLUTs), the "active" glucose transporters (sodium-dependent glucose transporters, SGLTs), and the SLC50 family of uniporters (sugars will eventually be exported transporters, SWEETs). Glucose transport across the blood-retinal barrier (BRB) is crucial for nourishing the neuronal retina in the context of retinal physiology. This physiological process primarily relies on GLUTs and SGLTs, which mediate the glucose transportation across both the cell membrane of retinal capillary endothelial cells and the retinal pigment epithelium (RPE). Under diabetic conditions, increased accumulation of extracellular glucose enhances the retinal cellular glucose uptake and metabolism via both glycolysis and glycolytic side branches, which activates several biochemical pathways, including the protein kinase C (PKC), advanced glycation end-products (AGEs), polyol pathway and hexosamine biosynthetic pathway (HBP). These activated biochemical pathways further increase the production of reactive oxygen species (ROS), leading to oxidative stress and activation of Poly (ADP-ribose) polymerase (PARP). The activated PARP further affects all the cellular components in the retina, and finally resulting in microangiopathy, neurodegeneration and low-to-moderate grade inflammation in DR. This review aims to discuss the changes of glucose transport, glucose transporters, as well as its metabolism in DR, which influences the retinal neurovascular unit (NVU) and implies the possible therapeutic strategies for treating DR.
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Affiliation(s)
- Chaoyang Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Limin Gu
- Department of Ophthalmology, Shanghai Aier Eye Hospital, Shanghai, China.
| | - Hai Xie
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Yan Liu
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Peirong Huang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Jingting Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Dawei Luo
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
| | - Jingfa Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases; Shanghai Clinical Research Center for Eye Diseases; Shanghai Key Clinical Specialty; Shanghai Key Laboratory of Ocular Fundus Diseases; Shanghai Engineering Center for Visual Science and Photomedicine; Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai Eye Research Institute, Shanghai, China.
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Yuan M, He Q, Xiang W, Deng Y, Lin S, Zhang R. Natural compounds efficacy in Ophthalmic Diseases: A new twist impacting ferroptosis. Biomed Pharmacother 2024; 172:116230. [PMID: 38350366 DOI: 10.1016/j.biopha.2024.116230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/18/2024] [Accepted: 01/29/2024] [Indexed: 02/15/2024] Open
Abstract
Ferroptosis, a distinct form of cell death, is characterized by the iron-mediated oxidation of lipids and is finely controlled by multiple cellular metabolic pathways. These pathways encompass redox balance, iron regulation, mitochondrial function, as well as amino acid, lipid, and sugar metabolism. Additionally, various disease-related signaling pathways also play a role in the regulation of ferroptosis. In recent years, with the introduction of the concept of ferroptosis and the deepening of research on its mechanism, ferroptosis is closely related to various biological conditions of eye diseases, including eye organ development, aging, immunity, and cancer. This article reviews the development of the concept of ferroptosis, the mechanism of ferroptosis, and its latest research progress in ophthalmic diseases and reviews the research on ferroptosis in ocular diseases within the framework of metabolism, active oxygen biology, and iron biology. Key regulators and mechanisms of ferroptosis in ocular diseases introduce important concepts and major open questions in the field of ferroptosis and related natural compounds. It is hoped that in future research, further breakthroughs will be made in the regulation mechanism of ferroptosis and the use of ferroptosis to promote the treatment of eye diseases. At the same time, natural compounds may be the direction of new drug development for the potential treatment of ferroptosis in the future. Open up a new way for clinical ophthalmologists to research and prevent diseases.
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Affiliation(s)
- Mengxia Yuan
- Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, China.
| | - Qi He
- People's Hospital of Ningxiang City, Ningxiang, China
| | - Wang Xiang
- The First People's Hospital of Changde City, Changde, China
| | - Ying Deng
- People's Hospital of Ningxiang City, Ningxiang, China
| | - Shibin Lin
- Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, China
| | - Riping Zhang
- Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, China.
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Ogura J, Sato T, Higuchi K, Sivaprakasam S, Kopel J, Bhutia YD, Ganapathy V. Binding of Citrate-Fe 3+ to Plastic Culture Dishes, an Artefact Useful as a Simple Technique to Screen for New Iron Chelators. Int J Mol Sci 2022; 23:ijms23126657. [PMID: 35743100 PMCID: PMC9223814 DOI: 10.3390/ijms23126657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/05/2022] [Accepted: 06/09/2022] [Indexed: 11/21/2022] Open
Abstract
NaCT mediates citrate uptake in the liver cell line HepG2. When these cells were exposed to iron (Fe3+), citrate uptake/binding as monitored by the association of [14C]-citrate with cells increased. However, there was no change in NaCT expression and function, indicating that NaCT was not responsible for this Fe3+-induced citrate uptake/binding. Interestingly however, the process exhibited substrate selectivity and saturability as if the process was mediated by a transporter. Notwithstanding these features, subsequent studies demonstrated that the iron-induced citrate uptake/binding did not involve citrate entry into cells; instead, the increase was due to the formation of citrate-Fe3+ chelate that adsorbed to the cell surface. Surprisingly, the same phenomenon was observed in culture wells without HepG2 cells, indicating the adsorption of the citrate-Fe3+ chelate to the plastic surface of culture wells. We used this interesting phenomenon as a simple screening technique for new iron chelators with the logic that if another iron chelator is present in the assay system, it would compete with citrate for binding to Fe3+ and prevent the formation and adsorption of citrate-Fe3+ to the culture well. This technique was validated with the known iron chelators deferiprone and deferoxamine, and with the bacterial siderophore 2,3-dihydroxybenzoic acid and the catechol carbidopa.
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Affiliation(s)
- Jiro Ogura
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
- Graduate School of Pharmaceutical Sciences, Yamagata University, Yamagata 990-8560, Japan
| | - Toshihiro Sato
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
- Department of Pharmaceutical Sciences, Tohoku University Hospital, Sendai 980-8574, Japan
| | - Kei Higuchi
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
- Department of Pharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo 192-0392, Japan
| | - Sathish Sivaprakasam
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
| | - Jonathan Kopel
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
| | - Yangzom D. Bhutia
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; (J.O.); (T.S.); (K.H.); (S.S.); (J.K.); (Y.D.B.)
- Correspondence: ; Tel.: +1-(806)-743-2518
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Hereditary hemochromatosis promotes colitis and colon cancer and causes bacterial dysbiosis in mice. Biochem J 2021; 477:3867-3883. [PMID: 32955078 PMCID: PMC7557149 DOI: 10.1042/bcj20200392] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/17/2020] [Accepted: 09/21/2020] [Indexed: 12/24/2022]
Abstract
Hereditary hemochromatosis (HH), an iron-overload disease, is a prevalent genetic disorder. As excess iron causes a multitude of metabolic disturbances, we postulated that iron overload in HH disrupts colonic homeostasis and colon–microbiome interaction and exacerbates the development and progression of colonic inflammation and colon cancer. To test this hypothesis, we examined the progression and severity of colitis and colon cancer in a mouse model of HH (Hfe−/−), and evaluated the potential contributing factors. We found that experimentally induced colitis and colon cancer progressed more robustly in Hfe−/− mice than in wild-type mice. The underlying causes were multifactorial. Hfe−/− colons were leakier with lower proliferation capacity of crypt cells, which impaired wound healing and amplified inflammation-driven tissue injury. The host/microflora axis was also disrupted. Sequencing of fecal 16S RNA revealed profound changes in the colonic microbiome in Hfe−/− mice in favor of the pathogenic bacteria belonging to phyla Proteobacteria and TM7. There was an increased number of bacteria adhered onto the mucosal surface of the colonic epithelium in Hfe−/− mice than in wild-type mice. Furthermore, the expression of innate antimicrobial peptides, the first-line of defense against bacteria, was lower in Hfe−/− mouse colon than in wild-type mouse colon; the release of pro-inflammatory cytokines upon inflammatory stimuli was also greater in Hfe−/− mouse colon than in wild-type mouse colon. These data provide evidence that excess iron accumulation in colonic tissue as happens in HH promotes colitis and colon cancer, accompanied with bacterial dysbiosis and loss of function of the intestinal/colonic barrier.
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Haferkamp S, Drexler K, Federlin M, Schlitt HJ, Berneburg M, Adamski J, Gaumann A, Geissler EK, Ganapathy V, Parkinson EK, Mycielska ME. Extracellular Citrate Fuels Cancer Cell Metabolism and Growth. Front Cell Dev Biol 2020; 8:602476. [PMID: 33425906 PMCID: PMC7793864 DOI: 10.3389/fcell.2020.602476] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/16/2020] [Indexed: 12/13/2022] Open
Abstract
Cancer cells need excess energy and essential nutrients/metabolites not only to divide and proliferate but also to migrate and invade distant organs for metastasis. Fatty acid and cholesterol synthesis, considered a hallmark of cancer for anabolism and membrane biogenesis, requires citrate. We review here potential pathways in which citrate is synthesized and/or supplied to cancer cells and the impact of extracellular citrate on cancer cell metabolism and growth. Cancer cells employ different mechanisms to support mitochondrial activity and citrate synthesis when some of the necessary substrates are missing in the extracellular space. We also discuss the different transport mechanisms available for the entry of extracellular citrate into cancer cells and how citrate as a master metabolite enhances ATP production and fuels anabolic pathways. The available literature suggests that cancer cells show an increased metabolic flexibility with which they tackle changing environmental conditions, a phenomenon crucial for cancer cell proliferation and metastasis.
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Affiliation(s)
| | - Konstantin Drexler
- Department of Dermatology, University Medical Center, Regensburg, Germany
| | - Marianne Federlin
- Department of Conservative Dentistry and Periodontology, University Medical Center, Regensburg, Germany
| | - Hans J Schlitt
- Department of Surgery, University Medical Center Regensburg, Regensburg, Germany
| | - Mark Berneburg
- Department of Dermatology, University Medical Center, Regensburg, Germany
| | - Jerzy Adamski
- Research Unit Molecular Endocrinology and Metabolism, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.,Lehrstuhl für Experimentelle Genetik, Technische Universität München, Munich, Germany.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Andreas Gaumann
- Institute of Pathology, Kaufbeuren-Ravensburg, Kaufbeuren, Germany
| | - Edward K Geissler
- Department of Surgery, University Medical Center Regensburg, Regensburg, Germany
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - E Kenneth Parkinson
- Center for Immunobiology and Regenerative Medicine, Barts and The London School of Medicine and Dentistry, Blizard Institute, London, United Kingdom
| | - Maria E Mycielska
- Department of Surgery, University Medical Center Regensburg, Regensburg, Germany
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Luo H, Ma C. Identification of prognostic genes in uveal melanoma microenvironment. PLoS One 2020; 15:e0242263. [PMID: 33196683 PMCID: PMC7668584 DOI: 10.1371/journal.pone.0242263] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 10/30/2020] [Indexed: 12/22/2022] Open
Abstract
Background Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Many previous studies have demonstrated that the infiltrating of immune and stromal cells in the tumor microenvironment contributes significantly to prognosis. Methods Dataset TCGA-UVM, download from TCGA portal, was taken as the training cohort, and GSE22138, obtained from GEO database, was set as the validation cohort. ESTIMATE algorithm was applied to find intersection differentially expressed genes (DEGs) among tumor microenvironment. Kaplan-Meier analysis and univariate Cox regression model were performed on intersection DEGs to initial screen for potential prognostic genes. Then these genes entered into the validation cohort for validation using the same methods as that in the training cohort. Moreover, we conducted correlation analyses between the genes obtained in the validation cohort and the status of chromosome 3, chromosome 8q, and tumor metastasis to get prognosis genes. At last, the immune infiltration analysis was performed between the prognostic genes and 6 main kinds of tumor-infiltrating immune cells (TICs) for understanding the role of the genes in the tumor microenvironment. Results 959 intersection DEGs were found in the UM microenvironment. Kaplan-Meier and Cox analysis was then performed in the training and validation cohorts on these DEGs, and 52 genes were identified with potential prognostic value. After comparing the 52 genes to chromosome 3, chromosome 8q, and metastasis, we obtained 21 genes as the prognostic genes. The immune infiltration analysis showed that Neutrophil had the potential prognostic ability, and almost every prognostic gene we had identified was correlated with abundances of Neutrophil and CD8+ T Cell. Conclusions Identifying 21 prognosis genes (SERPINB9, EDNRB, RAPGEF3, HFE, RNF43, ZNF415, IL12RB2, MTUS1, NEDD9, ZNF667, AZGP1, WARS, GEM, RAB31, CALHM2, CA12, MYEOV, CELF2, SLCO5A1, ISM1, and PAPSS2) could accurately identify patients' prognosis and had close interactions with Neutrophil in the tumor environment, which may provide UM patients with personalized prognosis prediction and new treatment insights.
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Affiliation(s)
- Huan Luo
- Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany
- Klinik für Augenheilkunde, Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Chao Ma
- Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and the Berlin Institute of Health, Berlin, Germany
- BCRT—Berlin Institute of Health Center for Regenerative Therapies, Charité—Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Li X, He S, Zhao M. An Updated Review of the Epigenetic Mechanism Underlying the Pathogenesis of Age-related Macular Degeneration. Aging Dis 2020; 11:1219-1234. [PMID: 33014534 PMCID: PMC7505275 DOI: 10.14336/ad.2019.1126] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 11/26/2019] [Indexed: 12/27/2022] Open
Abstract
Epigenetics has been recognized to play an important role in physiological and pathological processes of the human body. Accumulating evidence has indicated that epigenetic mechanisms contribute to the pathogenesis of age-related macular degeneration (AMD). Although the susceptibility related to genetic variants has been revealed by genome-wide association studies, those genetic variants may predict AMD risk only in certain human populations. Other mechanisms, particularly those involving epigenetic factors, may play an important role in the pathogenesis of AMD. Therefore, we briefly summarize the most recent reports related to such epigenetic mechanisms, including DNA methylation, histone modification, and non-coding RNA, and the interplay of genetic and epigenetic factors in the pathogenesis of AMD.
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Affiliation(s)
- Xiaohua Li
- 1Henan Provincial People's Hospital, Zhengzhou, China.,2Henan Eye Hospital, Henan Eye Institute, Henan Key Laboratory of Ophthalmology and Visual Science, Zhengzhou, China.,3People's Hospital of Zhengzhou University, Zhengzhou, China.,4People's Hospital of Henan University, Zhengzhou, China
| | - Shikun He
- 1Henan Provincial People's Hospital, Zhengzhou, China.,2Henan Eye Hospital, Henan Eye Institute, Henan Key Laboratory of Ophthalmology and Visual Science, Zhengzhou, China.,3People's Hospital of Zhengzhou University, Zhengzhou, China.,4People's Hospital of Henan University, Zhengzhou, China.,5Departments of Pathology and Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.,6Ophthalmology Optometry Centre, Peking University People's Hospital, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, Beijing, China
| | - Mingwei Zhao
- 6Ophthalmology Optometry Centre, Peking University People's Hospital, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, Beijing, China
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Bhutia YD, Ogura J, Grippo PJ, Torres C, Sato T, Wachtel M, Ramachandran S, Babu E, Sivaprakasam S, Rajasekaran D, Schniers B, On N, Smoot L, Thangaraju M, Gnana-Prakasam JP, Ganapathy V. Chronic exposure to excess iron promotes EMT and cancer via p53 loss in pancreatic cancer. Asian J Pharm Sci 2020; 15:237-251. [PMID: 32373202 PMCID: PMC7193456 DOI: 10.1016/j.ajps.2020.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 01/19/2020] [Accepted: 02/12/2020] [Indexed: 12/15/2022] Open
Abstract
Based on the evidence that hemochromatosis, an iron-overload disease, drives hepatocellular carcinoma, we hypothesized that chronic exposure to excess iron, either due to genetic or environmental causes, predisposes an individual to cancer. Using pancreatic cancer as our primary focus, we employed cell culture studies to interrogate the connection between excess iron and cancer, and combined in vitro and in vivo studies to explore the connection further. Ferric ammonium citrate was used as an exogenous iron source. Chronic exposure to excess iron induced epithelial-mesenchymal transition (EMT) in normal and cancer cell lines, loss of p53, and suppression of p53 transcriptional activity evidenced from decreased expression of p53 target genes (p21, cyclin D1, Bax, SLC7A11). To further extrapolate our cell culture data, we generated EL-KrasG12D (EL-Kras) mouse (pancreatic neoplastic mouse model) expressing Hfe+/+and Hfe−/− genetic background. p53 target gene expression decreased in EL-Kras/Hfe−/− mouse pancreas compared to EL-Kras/Hfe+/+ mouse pancreas. Interestingly, the incidence of acinar-to-ductal metaplasia and cystic pancreatic neoplasms (CPN) decreased in EL-Kras/Hfe−/− mice, but the CPNs that did develop were larger in these mice than in EL-Kras/Hfe+/+ mice. In conclusion, these in vitro and in vivo studies support a potential role for chronic exposure to excess iron as a promoter of more aggressive disease via p53 loss and SLC7A11 upregulation within pancreatic epithelial cells.
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Affiliation(s)
- Yangzom D Bhutia
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Jiro Ogura
- Department of Pharmaceutical Sciences, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan
| | - Paul J Grippo
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Carolina Torres
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Toshihiro Sato
- Department of Pharmaceutical Sciences, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan
| | - Mitchell Wachtel
- Department of Surgical Pathology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sabarish Ramachandran
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Ellappan Babu
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sathish Sivaprakasam
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Devaraja Rajasekaran
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Bradley Schniers
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Nhu On
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79410, USA.,Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79410, USA
| | - Logan Smoot
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79410, USA
| | - Muthusamy Thangaraju
- Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA 30912, USA
| | | | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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DUAN L, YIN X, MENG H, FANG X, MIN J, WANG F. [Progress on epigenetic regulation of iron homeostasis]. Zhejiang Da Xue Xue Bao Yi Xue Ban 2020; 49:58-70. [PMID: 32621410 PMCID: PMC8800797 DOI: 10.3785/j.issn.1008-9292.2020.02.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Iron homeostasis plays an important role for the maintenance of human health. It is known that iron metabolism is tightly regulated by several key genes, including divalent metal transport-1(DMT1), transferrin receptor 1(TFR1), transferrin receptor 2(TFR2), ferroportin(FPN), hepcidin(HAMP), hemojuvelin(HJV) and Ferritin H. Recently, it is reported that DNA methylation, histone acetylation, and microRNA (miRNA) epigenetically regulated iron homeostasis. Among these epigenetic regulators, DNA hypermethylation of the promoter region of FPN, TFR2, HAMP, HJV and bone morphogenetic protein 6 (BMP6) genes result in inhibitory effect on the expression of these iron-related gene. In addition, histone deacetylase (HADC) suppresses HAMP gene expression. On the contrary, HADC inhibitor upregulates HAMP gene expression. Additional reports showed that miRNA can also modulate iron absorption, transport, storage and utilization via downregulation of DMT1, FPN, TFR1, TFR2, Ferritin H and other genes. It is noteworthy that some key epigenetic regulatory enzymes, such as DNA demethylase TET2 and histone lysine demethylase JmjC KDMs, require iron for the enzymatic activities. In this review, we summarize the recent progress of DNA methylation, histone acetylation and miRNA in regulating iron metabolism and also discuss the future research directions.
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Mohana Devi S, Mahalaxmi I, Kaavya J, Chinnkulandhai V, Balachandar V. Does epigenetics have a role in age related macular degeneration and diabetic retinopathy? Genes Dis 2020; 8:279-286. [PMID: 33997175 PMCID: PMC8093576 DOI: 10.1016/j.gendis.2020.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/06/2020] [Indexed: 02/08/2023] Open
Abstract
Epigenetic mechanisms play an important part in the regulation of gene expression and these alterations may induce long-term changes in gene function and metabolism. They have received extensive attention in bridging the gap between environmental exposures and disease development via their influence on gene expression. DNA methylation is the earliest discovered epigenetic alteration. In this review, we try to examine the role of DNA methylation and histone modification in Age related macular degeneration (AMD) and Diabetic Retinopathy (DR), its vascular complications and recent progress. Given the complex nature of AMD and DR, it is crucial to improve therapeutics which will greatly enhance the quality of life and reduce the burden for millions of patients living with these potentially blinding conditions.
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Affiliation(s)
- S Mohana Devi
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Sankara Nethralaya, 41/18, College Road, Chennai, 600006, India
| | - I Mahalaxmi
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Avinashilingam University for Women, Coimbatore, Tamil Nadu, 641046, India
| | - J Kaavya
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Avinashilingam University for Women, Coimbatore, Tamil Nadu, 641046, India
| | - V Chinnkulandhai
- Department of Biochemistry, Dr.N.G.P Arts and Science College, Coimbatore, Tamil Nadu, 641046, India
| | - V Balachandar
- Human Molecular Genetics and Stem Cells Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
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Chaudhary K, Promsote W, Ananth S, Veeranan-Karmegam R, Tawfik A, Arjunan P, Martin P, Smith SB, Thangaraju M, Kisselev O, Ganapathy V, Gnana-Prakasam JP. Iron Overload Accelerates the Progression of Diabetic Retinopathy in Association with Increased Retinal Renin Expression. Sci Rep 2018; 8:3025. [PMID: 29445185 PMCID: PMC5813018 DOI: 10.1038/s41598-018-21276-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/31/2018] [Indexed: 12/31/2022] Open
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness among working-age adults. Increased iron accumulation is associated with several degenerative diseases. However, there are no reports on the status of retinal iron or its implications in the pathogenesis of DR. In the present study, we found that retinas of type-1 and type-2 mouse models of diabetes have increased iron accumulation compared to non-diabetic retinas. We found similar iron accumulation in postmortem retinal samples from human diabetic patients. Further, we induced diabetes in HFE knockout (KO) mice model of genetic iron overload to understand the role of iron in the pathogenesis of DR. We found increased neuronal cell death, vascular alterations and loss of retinal barrier integrity in diabetic HFE KO mice compared to diabetic wildtype mice. Diabetic HFE KO mouse retinas also exhibited increased expression of inflammation and oxidative stress markers. Severity in the pathogenesis of DR in HFE KO mice was accompanied by increase in retinal renin expression mediated by G-protein-coupled succinate receptor GPR91. In light of previous reports implicating retinal renin-angiotensin system in DR pathogenesis, our results reveal a novel relationship between diabetes, iron and renin-angiotensin system, thereby unraveling new therapeutic targets for the treatment of DR.
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Affiliation(s)
- Kapil Chaudhary
- Department of Medicine, Washington University, St. Louis, Missouri, USA
| | | | - Sudha Ananth
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Rajalakshmi Veeranan-Karmegam
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Amany Tawfik
- Dental College of Georgia, Augusta University, Augusta, Georgia, USA
| | | | - Pamela Martin
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Muthusamy Thangaraju
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Oleg Kisselev
- Department of Ophthalmology and Department of Biochemistry & Molecular Biology, Saint Louis University, St. Louis, Missouri, USA
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Jaya P Gnana-Prakasam
- Department of Ophthalmology and Department of Biochemistry & Molecular Biology, Saint Louis University, St. Louis, Missouri, USA.
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13
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Herat LY, Matthews VB, Rakoczy PE, Carnagarin R, Schlaich M. Focusing on Sodium Glucose Cotransporter-2 and the Sympathetic Nervous System: Potential Impact in Diabetic Retinopathy. Int J Endocrinol 2018; 2018:9254126. [PMID: 30123269 PMCID: PMC6079487 DOI: 10.1155/2018/9254126] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/14/2018] [Indexed: 12/21/2022] Open
Abstract
The prevalence of diabetes is at pandemic levels in today's society. Microvascular complications in organs including the eye are commonly observed in human diabetic subjects. Diabetic retinopathy (DR) is a prominent microvascular complication observed in many diabetics and is particularly debilitating as it may result in impaired or complete vision loss. In addition, DR is extremely costly for the patient and financially impacts the economy as a range of drug-related therapies and laser treatment may be essential. Prevention of microvascular complications is the major treatment goal of current therapeutic approaches; however, these therapies appear insufficient. Presently, sodium glucose cotransporter-2 (SGLT2) inhibitors may offer a novel therapy beyond simple glucose lowering. Excitingly, the EMPA-REG clinical trial, which focuses on the clinically used SGLT2 inhibitor empagliflozin, has been extremely fruitful and has highlighted beneficial cardiovascular and renal outcomes. The effects of SGLT2 inhibitors on DR are currently a topic of much research as outlined in the current review, but future studies are urgently needed to fully gain mechanistic insights. Here, we summarize current evidence and identify gaps that need to be addressed.
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Affiliation(s)
- Lakshini Y. Herat
- Dobney Hypertension Centre, School of Biomedical Science, University of Western Australia, Crawley, WA, Australia
| | - Vance B. Matthews
- Dobney Hypertension Centre, School of Biomedical Science, University of Western Australia, Crawley, WA, Australia
| | | | - Revathy Carnagarin
- Dobney Hypertension Centre, School of Medicine, University of Western Australia, Crawley, WA, Australia
| | - Markus Schlaich
- Dobney Hypertension Centre, School of Medicine, University of Western Australia, Crawley, WA, Australia
- Department of Cardiology and Department of Nephrology, Royal Perth Hospital, Perth, WA, Australia
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14
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Asimakopoulou A, Weiskirchen S, Weiskirchen R. Pathogenesis, Diagnostics, and Treatment of Hereditary Haemochromatosis: A 150 Year-Long Understanding of an Iron Overload Disorder. EUROPEAN MEDICAL JOURNAL 2017. [DOI: 10.33590/emj/10310080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Haemochromatosis is an iron overload disorder that can be inherited or acquired and when diagnosis is delayed, disease progression and death can occur. Iron overload was first described by the French internist Armand Trousseau in 1865 in an article on diabetes in which alterations in skin pigmentations were reported. Some years later, the German pathologist Friedrich Daniel von Recklinghausen coined the term ‘haemochromatosis’ for a metabolic disorder characterised by excess deposition of iron in the tissue. This disorder affects 1 in 200 subjects of Caucasians of Northern European descent. The systemic excess iron build-up condition quickly gained an intense clinical interest. Haemochromatosis can lead to severe pathological symptoms in multiple organs, including the liver, bones, spleen, heart, pancreas, joints, and reproductive organs. With the progress of the disease, hepatic damage predominates. Polymorphisms in several independent genes can lead to haemochromatosis. However, the most widely known haemochromatosis-associated and studied ones are genetic variants in the HFE gene, located on the short arm of human chromosome 6. Early detection and phlebotomy prior to the onset of fibrosis/cirrhosis can reduce morbidity and normalise life expectancy. Consequently, phlebotomy has been accepted for decades as a standard treatment for the reduction of iron load. Nowadays, other methods, such as erythrocytapheresis, therapeutic application of iron chelators and proton pump inhibitors, or hepcidin-targeted therapy, are discussed as alternative personalised treatments of hereditary haemochromatosis. This review focusses on the pathogenesis, diagnosis, and therapy of haemochromatosis.
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Affiliation(s)
- Anastasia Asimakopoulou
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
| | - Sabine Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
| | - Ralf Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, Aachen, Germany
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15
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Rishi G, Subramaniam VN. The liver in regulation of iron homeostasis. Am J Physiol Gastrointest Liver Physiol 2017; 313:G157-G165. [PMID: 28596277 DOI: 10.1152/ajpgi.00004.2017] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 05/31/2017] [Accepted: 05/31/2017] [Indexed: 01/31/2023]
Abstract
The liver is one of the largest and most functionally diverse organs in the human body. In addition to roles in detoxification of xenobiotics, digestion, synthesis of important plasma proteins, gluconeogenesis, lipid metabolism, and storage, the liver also plays a significant role in iron homeostasis. Apart from being the storage site for excess body iron, it also plays a vital role in regulating the amount of iron released into the blood by enterocytes and macrophages. Since iron is essential for many important physiological and molecular processes, it increases the importance of liver in the proper functioning of the body's metabolism. This hepatic iron-regulatory function can be attributed to the expression of many liver-specific or liver-enriched proteins, all of which play an important role in the regulation of iron homeostasis. This review focuses on these proteins and their known roles in the regulation of body iron metabolism.
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Affiliation(s)
- Gautam Rishi
- Liver Disease and Iron Disorders Research Group, Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia
| | - V Nathan Subramaniam
- Liver Disease and Iron Disorders Research Group, Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia
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16
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Arjunan P, Gnanaprakasam JP, Ananth S, Romej MA, Rajalakshmi VK, Prasad PD, Martin PM, Gurusamy M, Thangaraju M, Bhutia YD, Ganapathy V. Increased Retinal Expression of the Pro-Angiogenic Receptor GPR91 via BMP6 in a Mouse Model of Juvenile Hemochromatosis. Invest Ophthalmol Vis Sci 2016; 57:1612-9. [PMID: 27046124 PMCID: PMC4824383 DOI: 10.1167/iovs.15-17437] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Hemochromatosis, an iron-overload disease, occurs as adult and juvenile types. Mutations in hemojuvelin (HJV), an iron-regulatory protein and a bone morphogenetic protein (BMP) coreceptor, underlie most of the juvenile type. Hjv(-/-) mice accumulate excess iron in retina and exhibit aberrant vascularization and angiomas. A succinate receptor, GPR91, is pro-angiogenic in retina. We hypothesized that Hjv(-/-) retinas have increased BMP signaling and increased GPR91 expression as the basis of angiomas. METHODS Expression of GPR91 was examined by qPCR, immunofluorescence, and Western blot in wild-type and Hjv(-/-) mouse retinas and pRPE cells. Influence of excess iron and BMP6 on GPR91 expression was investigated in ARPE-19 cells, and wild-type and Hjv(-/-) pRPE cells. Succinate was used to activate GPR91 and determine the effects of GPR91 signaling on VEGF expression. Signaling of BMP6 was studied by the expression of Smad1/5/8 and pSmad4, and the BMP-target gene Id1. The interaction of pSmad4 with GPR91 promoter was studied by ChIP. RESULTS Expression of GPR91 was higher in Hjv(-/-) retinas and RPE than in wild-type counterparts. Unexpectedly, BMP signaling was increased, not decreased, in Hjv(-/-) retinas and RPE. Bone morphogenetic protein 6 induced GPR91 in RPE, suggesting that increased BMP signaling in Hjv(-/-) retinas was likely responsible for GPR91 upregulation. Exposure of RPE to excess iron and succinate as well as BMP6 and succinate increased VEGF expression. Bone morphogenetic protein 6 promoted the interaction of pSmad4 with GPR91 promoter in RPE. CONCLUSIONS G-protein-coupled receptor 91 is a BMP6 target and Hjv deletion enhances BMP signaling in retina, thus underscoring a role for excess iron and hemochromatosis in abnormal retinal vascularization.
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Affiliation(s)
- Pachiappan Arjunan
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 2Department of Periodontics, Georgia Regents University, Augusta, Georgia, United States
| | - Jaya P Gnanaprakasam
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Sudha Ananth
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Michelle A Romej
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | | | - Puttur D Prasad
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Pamela M Martin
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Mariappan Gurusamy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Muthusamy Thangaraju
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Yangzom D Bhutia
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 3Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 3Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
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17
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Epigenetic modifications as potential therapeutic targets in age-related macular degeneration and diabetic retinopathy. Drug Discov Today 2014; 19:1387-93. [DOI: 10.1016/j.drudis.2014.03.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 03/12/2014] [Accepted: 03/31/2014] [Indexed: 12/14/2022]
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18
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Tawfik A, Gnana-Prakasam JP, Smith SB, Ganapathy V. Deletion of hemojuvelin, an iron-regulatory protein, in mice results in abnormal angiogenesis and vasculogenesis in retina along with reactive gliosis. Invest Ophthalmol Vis Sci 2014; 55:3616-25. [PMID: 24812553 DOI: 10.1167/iovs.13-13677] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE Loss-of-function mutations in hemojuvelin (HJV) cause juvenile hemochromatosis, an iron-overload disease. Deletion of Hjv in mice results in excessive iron accumulation and morphologic changes in the retina. Here, we studied the retinal vasculature in Hjv(-/-) mice. METHODS Age-matched wild-type and Hjv(-/-) mice were used for fluorescein angiography and preparation of retinal cryosections, flat-mounts, and trypsin-digested blood vessels. Retinal angiogenesis was monitored by immunofluorescent detection of isolectin-B4, endoglin, and VEGF. Retinal vasculogenesis was monitored by immunofluorescent detection of collagen IV. Reactive gliosis was assessed based on the expression of glial fibrillary acidic protein and vimentin and CD11b/c as markers for Müller cells and microglia. RESULTS Between 18 and 24 months of age, retinas of Hjv(-/-) mice displayed marked disruptions in angiogenesis and vasculogenesis. Blood vessels in Hjv(-/-) mice were tortuous and dilated, with a decrease in the tight-junction protein occludin. There was also evidence of neovascularization in Hjv(-/-) mice with blood vessels appearing in the vitreous, which were leaky. There was reactive gliosis in these mice involving both Müller cells and microglia. Such changes were not detected at 2 weeks of age. Even at the age of 4 months, retinas of Hjv(-/-) mice were almost normal with changes just beginning to appear. Thus, the vascular changes in Hjv(-/-) mouse retinas represent an age-dependent phenomenon. CONCLUSIONS Deletion of Hjv in mice leads to abnormal retinal angiogenesis/vasculogenesis, with proliferation of new, leaky blood vessels in the vitreous. These changes are accompanied with reactive gliosis involving Müller cells and microglia.
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Affiliation(s)
- Amany Tawfik
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Jaya P Gnana-Prakasam
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Vadivel Ganapathy
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
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Ananth S, Gnana-Prakasam JP, Bhutia YD, Veeranan-Karmegam R, Martin PM, Smith SB, Ganapathy V. Regulation of the cholesterol efflux transporters ABCA1 and ABCG1 in retina in hemochromatosis and by the endogenous siderophore 2,5-dihydroxybenzoic acid. Biochim Biophys Acta Mol Basis Dis 2014; 1842:603-12. [PMID: 24462739 DOI: 10.1016/j.bbadis.2014.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 01/08/2014] [Accepted: 01/13/2014] [Indexed: 01/19/2023]
Abstract
Hypercholesterolemia and polymorphisms in the cholesterol exporter ABCA1 are linked to age-related macular degeneration (AMD). Excessive iron in retina also has a link to AMD pathogenesis. Whether these findings mean a biological/molecular connection between iron and cholesterol is not known. Here we examined the relationship between retinal iron and cholesterol using a mouse model (Hfe(-/-)) of hemochromatosis, a genetic disorder of iron overload. We compared the expression of the cholesterol efflux transporters ABCA1 and ABCG1 and cholesterol content in wild type and Hfe(-/-) mouse retinas. We also investigated the expression of Bdh2, the rate-limiting enzyme in the synthesis of the endogenous siderophore 2,5-dihydroxybenzoic acid (2,5-DHBA) in wild type and Hfe(-/-) mouse retinas, and the influence of this siderophore on ABCA1/ABCG1 expression in retinal pigment epithelium. We found that ABCA1 and ABCG1 were expressed in all retinal cell types, and that their expression was decreased in Hfe(-/-) retina. This was accompanied with an increase in retinal cholesterol content. Bdh2 was also expressed in all retinal cell types, and its expression was decreased in hemochromatosis. In ARPE-19 cells, 2,5-DHBA increased ABCA1/ABCG1 expression and decreased cholesterol content. This was not due to depletion of free iron because 2,5-DHBA (a siderophore) and deferiprone (an iron chelator) had opposite effects on transferrin receptor expression and ferritin levels. We conclude that iron is a regulator of cholesterol homeostasis in retina and that removal of cholesterol from retinal cells is impaired in hemochromatosis. Since excessive cholesterol is pro-inflammatory, hemochromatosis might promote retinal inflammation via cholesterol in AMD.
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Affiliation(s)
- Sudha Ananth
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Jaya P Gnana-Prakasam
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Yangzom D Bhutia
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | | | - Pamela M Martin
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Georgia Regents University, Augusta, GA 30912, USA
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, GA 30912, USA.
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