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Li J, Chen K, Li X, Zhang X, Zhang L, Yang Q, Xia Y, Xie C, Wang X, Tong J, Shen Y. Mechanistic insights into the alterations and regulation of the AKT signaling pathway in diabetic retinopathy. Cell Death Discov 2023; 9:418. [PMID: 37978169 PMCID: PMC10656479 DOI: 10.1038/s41420-023-01717-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 11/05/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023] Open
Abstract
In the early stages of diabetic retinopathy (DR), diabetes-related hyperglycemia directly inhibits the AKT signaling pathway by increasing oxidative stress or inhibiting growth factor expression, which leads to retinal cell apoptosis, nerve proliferation and fundus microvascular disease. However, due to compensatory vascular hyperplasia in the late stage of DR, the vascular endothelial growth factor (VEGF)/phosphatidylinositol 3 kinase (PI3K)/AKT cascade is activated, resulting in opposite levels of AKT regulation compared with the early stage. Studies have shown that many factors, including insulin, insulin-like growth factor-1 (IGF-1), VEGF and others, can regulate the AKT pathway. Disruption of the insulin pathway decreases AKT activation. IGF-1 downregulation decreases the activation of AKT in DR, which abrogates the neuroprotective effect, upregulates VEGF expression and thus induces neovascularization. Although inhibiting VEGF is the main treatment for neovascularization in DR, excessive inhibition may lead to apoptosis in inner retinal neurons. AKT pathway substrates, including mammalian target of rapamycin (mTOR), forkhead box O (FOXO), glycogen synthase kinase-3 (GSK-3)/nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor kappa-B (NF-κB), are a research focus. mTOR inhibitors can delay or prevent retinal microangiopathy, whereas low mTOR activity can decrease retinal protein synthesis. Inactivated AKT fails to inhibit FOXO and thus causes apoptosis. The GSK-3/Nrf2 cascade regulates oxidation and inflammation in DR. NF-κB is activated in diabetic retinas and is involved in inflammation and apoptosis. Many pathways or vital activities, such as the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) signaling pathways, interact with the AKT pathway to influence DR development. Numerous regulatory methods can simultaneously impact the AKT pathway and other pathways, and it is essential to consider both the connections and interactions between these pathways. In this review, we summarize changes in the AKT signaling pathway in DR and targeted drugs based on these potential sites.
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Affiliation(s)
- Jiayuan Li
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
- Department of Cardiology, The Second Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Kuangqi Chen
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiang Li
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Xuhong Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Liyue Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Qianjie Yang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Yutong Xia
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Chen Xie
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiawei Wang
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China
| | - Jianping Tong
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China.
| | - Ye Shen
- Department of Ophthalmology, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang, China.
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Gao AY, Haak AJ, Bakri SJ. In vitro laboratory models of proliferative vitreoretinopathy. Surv Ophthalmol 2023; 68:861-874. [PMID: 37209723 DOI: 10.1016/j.survophthal.2023.05.007] [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: 05/26/2022] [Revised: 05/13/2023] [Accepted: 05/15/2023] [Indexed: 05/22/2023]
Abstract
Proliferative vitreoretinopathy (PVR), the most common cause of recurrent retinal detachment, is characterized by the formation and contraction of fibrotic membranes on the surface of the retina. There are no Food and Drug Administration (FDA)-approved drugs to prevent or treat PVR. Therefore, it is necessary to develop accurate in vitro models of the disease that will enable researchers to screen drug candidates and prioritize the most promising candidates for clinical studies. We provide a summary of recent in vitro PVR models, as well as avenues for model improvement. Several in vitro PVR models were identified, including various types of cell cultures. Additionally, novel techniques that have not been used to model PVR were identified, including organoids, hydrogels, and organ-on-a-chip models. Novel ideas for improving in vitro PVR models are highlighted. Researchers may consult this review to help design in vitro models of PVR, which will aid in the development of therapies to treat the disease.
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Affiliation(s)
- Ashley Y Gao
- Mayo Clinic, Department of Ophthalmology, Rochester, Minnesota, USA
| | - Andrew J Haak
- Mayo Clinic, Department of Physiology and Biomedical Engineering, Rochester, Minnesota, USA
| | - Sophie J Bakri
- Mayo Clinic, Department of Ophthalmology, Rochester, Minnesota, USA.
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Lu F, Leach LL, Gross JM. mTOR activity is essential for retinal pigment epithelium regeneration in zebrafish. PLoS Genet 2022; 18:e1009628. [PMID: 35271573 PMCID: PMC8939802 DOI: 10.1371/journal.pgen.1009628] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 03/22/2022] [Accepted: 02/23/2022] [Indexed: 12/30/2022] Open
Abstract
The retinal pigment epithelium (RPE) plays numerous critical roles in maintaining vision and this is underscored by the prevalence of degenerative blinding diseases like age-related macular degeneration (AMD), in which visual impairment is caused by progressive loss of RPE cells. In contrast to mammals, zebrafish possess the ability to intrinsically regenerate a functional RPE layer after severe injury. The molecular underpinnings of this regenerative process remain largely unknown yet hold tremendous potential for developing treatment strategies to stimulate endogenous regeneration in the human eye. In this study, we demonstrate that the mTOR pathway is activated in RPE cells post-genetic ablation. Pharmacological and genetic inhibition of mTOR activity impaired RPE regeneration, while mTOR activation enhanced RPE recovery post-injury, demonstrating that mTOR activity is essential for RPE regeneration in zebrafish. RNA-seq of RPE isolated from mTOR-inhibited larvae identified a number of genes and pathways dependent on mTOR activity at early and late stages of regeneration; amongst these were components of the immune system, which is emerging as a key regulator of regenerative responses across various tissue and model systems. Our results identify crosstalk between macrophages/microglia and the RPE, wherein mTOR activity is required for recruitment of macrophages/microglia to the RPE injury site. Macrophages/microglia then reinforce mTOR activity in regenerating RPE cells. Interestingly, the function of macrophages/microglia in maintaining mTOR activity in the RPE appeared to be inflammation-independent. Taken together, these data identify mTOR activity as a key regulator of RPE regeneration and link the mTOR pathway to immune responses in facilitating RPE regeneration.
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Affiliation(s)
- Fangfang Lu
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lyndsay L. Leach
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jeffrey M. Gross
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Liu Y, Zheng Y, Zhou Y, Liu Y, Xie M, Meng W, An M. The expression and significance of mTORC1 in diabetic retinopathy. BMC Ophthalmol 2020; 20:297. [PMID: 32689970 PMCID: PMC7370483 DOI: 10.1186/s12886-020-01553-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 07/06/2020] [Indexed: 01/23/2023] Open
Abstract
Background To investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR. Methods A DR rat model was prepared by general feeding combined with intraperitoneal injection of 10% streptozotocin (60 mg/kg). The rats were randomly divided into a control group (NDM group) and a diabetes group (DM group). Three months later, the degrees of retinopathy was determined using hematoxylin and eosin staining, and the levels of p-S6, VEGF, and PEDF proteins were detected by immunohistochemistry and western blotting. Human retinal capillary endothelial cells (HRCECs) were cultured in high glucose (HG) conditions, then treated with rapamycin or transfected with siTSC1.The protein levels of p-S6 were assessed by western blotting. The 5-ethynyl-2′-deoxyuridine assay was used to detect cell proliferation, and the Transwell assay was used to detect cell migration. Results A DM rat model was successfully developed. The expressions of p-S6 and VEGF proteins were significantly increased in the DM group (p < 0.05), and the expression of PEDF protein was significantly decreased compared with the NDM group (p < 0.05). In vitro, the p-S6 protein, as well as cell proliferation and migration, in HG induced HRCECs were increased (p < 0.05) compared with the control (normal glucose) group (p < 0.05). After transfection with siTSC1 to activate mTORC1, the expression of p-S6, as well as cell proliferation and migration, were increased. In contrast, rapamycin decreased p-S6 expression, as well as proliferation and migration, in HG induced HRCECs compared to the control group (p < 0.05). Conclusion mTORC1 plays an important role in DR. After activation, mTORC1 induced expression of the p-S6 protein, regulated the expressions of VEGF and PEDF proteins, and changed the proliferation and migration of endothelial cells. The mTORC1 can therefore be used as a new target,as well as in the treatment of DR.
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Affiliation(s)
- Yanli Liu
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yarong Zheng
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yekai Zhou
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Yi Liu
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Mengxuan Xie
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Wenjing Meng
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China.,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China
| | - Meixia An
- The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510515, China. .,Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diesases, Guangzhou, China.
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Zhao J, Zhong W, Sun L, Yin Y, Zheng Y. Effect of chloride channel activity on retinal pigment cell proliferation and migration. Mol Med Rep 2017; 15:1771-1776. [PMID: 28259964 DOI: 10.3892/mmr.2017.6202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 12/15/2016] [Indexed: 11/06/2022] Open
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Croze RH, Thi WJ, Clegg DO. ROCK Inhibition Promotes Attachment, Proliferation, and Wound Closure in Human Embryonic Stem Cell-Derived Retinal Pigmented Epithelium. Transl Vis Sci Technol 2016; 5:7. [PMID: 27917311 PMCID: PMC5132148 DOI: 10.1167/tvst.5.6.7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 10/10/2016] [Indexed: 12/27/2022] Open
Abstract
Purpose Nonexudative (dry) age-related macular degeneration (AMD), a leading cause of blindness in the elderly, is associated with the loss of retinal pigmented epithelium (RPE) cells and the development of geographic atrophy, which are areas devoid of RPE cells and photoreceptors. One possible treatment option would be to stimulate RPE attachment and proliferation to replace dying/dysfunctional RPE and bring about wound repair. Clinical trials are underway testing injections of RPE cells derived from pluripotent stem cells to determine their safety and efficacy in treating AMD. However, the factors regulating RPE responses to AMD-associated lesions are not well understood. Here, we use cell culture to investigate the role of RhoA coiled coil kinases (ROCKs) in human embryonic stem cell–derived RPE (hESC-RPE) attachment, proliferation, and wound closure. Methods H9 hESC were spontaneously differentiated into RPE cells. hESC-RPE cells were treated with a pan ROCK1/2 or a ROCK2 only inhibitor; attachment, and proliferation and cell size within an in vitro scratch assay were examined. Results Pharmacological inhibition of ROCKs promoted hESC-RPE attachment and proliferation, and increased the rate of closure of in vitro wounds. ROCK inhibition decreased phosphorylation of cofilin and myosin light chain, suggesting that regulation of the cytoskeleton underlies the mechanism of action of ROCK inhibition. Conclusions ROCK inhibition promotes attachment, proliferation, and wound closure in H9 hESC-RPE cells. ROCK isoforms may have different roles in wound healing. Translational Relevance Modulation of the ROCK-cytoskeletal axis has potential in stimulating wound repair in transplanted RPE cells and attachment in cellular therapies.
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Affiliation(s)
- Roxanne H Croze
- Center for Stem Cell Biology and Engineering, Neuroscience Research Institute, Department of Molecular, Cellular & Developmental Biology, University of California, Santa Barbara, CA, USA
| | - William J Thi
- Center for Stem Cell Biology and Engineering, Neuroscience Research Institute, Department of Molecular, Cellular & Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Dennis O Clegg
- Center for Stem Cell Biology and Engineering, Neuroscience Research Institute, Department of Molecular, Cellular & Developmental Biology, University of California, Santa Barbara, CA, USA
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