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Upreti A, Padula SL, Weaver JM, Wagner BD, Kneller AM, Petulla AL, Lachke SA, Robinson ML. A Transcriptomics Analysis of the Regulation of Lens Fiber Cell Differentiation in the Absence of FGFRs and PTEN. Cells 2024; 13:1222. [PMID: 39056803 PMCID: PMC11274593 DOI: 10.3390/cells13141222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/28/2024] [Accepted: 07/17/2024] [Indexed: 07/28/2024] Open
Abstract
Adding 50% vitreous humor to the media surrounding lens explants induces fiber cell differentiation and a significant immune/inflammatory response. While Fgfr loss blocks differentiation in lens epithelial explants, this blockage is partially reversed by deleting Pten. To investigate the functions of the Fgfrs and Pten during lens fiber cell differentiation, we utilized a lens epithelial explant system and conducted RNA sequencing on vitreous humor-exposed explants lacking Fgfrs, or Pten or both Fgfrs and Pten. We found that Fgfr loss impairs both vitreous-induced differentiation and inflammation while the additional loss of Pten restores these responses. Furthermore, transcriptomic analysis suggested that PDGFR-signaling in FGFR-deficient explants is required to mediate the rescue of vitreous-induced fiber differentiation in explants lacking both Fgfrs and Pten. The blockage of β-crystallin induction in explants lacking both Fgfrs and Pten in the presence of a PDGFR inhibitor supports this hypothesis. Our findings demonstrate that a wide array of genes associated with fiber cell differentiation are downstream of FGFR-signaling and that the vitreous-induced immune responses also depend on FGFR-signaling. Our data also demonstrate that many of the vitreous-induced gene-expression changes in Fgfr-deficient explants are rescued in explants lacking both Fgfrs and Pten.
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Affiliation(s)
- Anil Upreti
- Cell, Molecular and Structural Biology Program, Miami University, Oxford, OH 45056, USA; (A.U.); (S.L.P.); (J.M.W.)
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Stephanie L. Padula
- Cell, Molecular and Structural Biology Program, Miami University, Oxford, OH 45056, USA; (A.U.); (S.L.P.); (J.M.W.)
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Jacob M. Weaver
- Cell, Molecular and Structural Biology Program, Miami University, Oxford, OH 45056, USA; (A.U.); (S.L.P.); (J.M.W.)
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Brad D. Wagner
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Allison M. Kneller
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Anthony L. Petulla
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
| | - Salil A. Lachke
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA;
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE 19716, USA
| | - Michael L. Robinson
- Cell, Molecular and Structural Biology Program, Miami University, Oxford, OH 45056, USA; (A.U.); (S.L.P.); (J.M.W.)
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA; (B.D.W.); (A.M.K.); (A.L.P.)
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2
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Regulation of lens water content: Effects on the physiological optics of the lens. Prog Retin Eye Res 2022:101152. [DOI: 10.1016/j.preteyeres.2022.101152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 12/09/2022]
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Beyer EC, Mathias RT, Berthoud VM. Loss of fiber cell communication may contribute to the development of cataracts of many different etiologies. Front Physiol 2022; 13:989524. [PMID: 36171977 PMCID: PMC9511111 DOI: 10.3389/fphys.2022.989524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
The lens is an avascular organ that is supported by an internal circulation of water and solutes. This circulation is driven by ion pumps, channels and transporters in epithelial cells and by ion channels in fiber cells and is maintained by fiber-fiber and fiber-epithelial cell communication. Gap junctional intercellular channels formed of connexin46 and connexin50 are critical components of this circulation as demonstrated by studies of connexin null mice and connexin mutant mice. Moreover, connexin mutants are one of the most common causes of autosomal dominant congenital cataracts. However, alterations of the lens circulation and coupling between lens fiber cells are much more prevalent, beyond the connexin mutant lenses. Intercellular coupling and levels of connexins are decreased with aging. Gap junction-mediated intercellular communication decreases in mice expressing mutant forms of several different lens proteins and in some mouse models of lens protein damage. These observations suggest that disruption of ionic homeostasis due to reduction of the lens circulation is a common component of the development of many different types of cataracts. The decrease in the lens circulation often reflects low levels of lens fiber cell connexins and/or functional gap junction channels.
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Affiliation(s)
- Eric C. Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL, United States
- *Correspondence: Eric C. Beyer,
| | - Richard T. Mathias
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, United States
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Sellitto C, Li L, White TW. Double Deletion of PI3K and PTEN Modifies Lens Postnatal Growth and Homeostasis. Cells 2022; 11:cells11172708. [PMID: 36078116 PMCID: PMC9455000 DOI: 10.3390/cells11172708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/23/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
We have previously shown that the conditional deletion of either the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K), or its opposing phosphatase, phosphatase and tensin homolog (PTEN), had distinct effects on lens growth and homeostasis. The deletion of p110α reduced the levels of phosphorylated Akt and equatorial epithelial cell proliferation, and resulted in smaller transparent lenses in adult mice. The deletion of PTEN increased levels of phosphorylated Akt, altered lens sodium transport, and caused lens rupture and cataract. Here, we have generated conditional p110α/PTEN double-knockout mice, and evaluated epithelial cell proliferation and lens homeostasis. The double deletion of p110α and PTEN rescued the defect in lens size seen after the single knockout of p110α, but accelerated the lens rupture phenotype seen in PTEN single-knockout mice. Levels of phosphorylated Akt in double-knockout lenses were significantly higher than in wild-type lenses, but not as elevated as those reported for PTEN single-knockout lenses. These results showed that the double deletion of the p110α catalytic subunit of PI3K and its opposing phosphatase, PTEN, exacerbated the rupture defect seen in the single PTEN knockout and alleviated the growth defect observed in the single p110α knockout. Thus, the integrity of the PI3K signaling pathway was absolutely essential for proper lens homeostasis, but not for lens growth.
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Cui N, Liu S, Zheng Z, Pi Z, Liu Z, Song F. The chemical profile of Fubai Chrysanthemum (Fubaiju) and its mechanism in preventing cataract based on ultrahigh-performance liquid chromatography coupled with mass spectrometry and network pharmacology. J Sep Sci 2022; 45:2406-2414. [PMID: 35490347 DOI: 10.1002/jssc.202100832] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 04/08/2022] [Accepted: 04/20/2022] [Indexed: 11/12/2022]
Abstract
Chrysanthemum is a kind of herb that can be used for both medicine and food. Although it has been shown to affect the redox damage of the lens, but the mechanism of action has not been systematically studied. This study identified the chemical profile of Fubai Chrysanthemum. Meanwhile, network pharmacology and the enrichment of the Kyoto encyclopedia of genes and genomes pathway were combined to investigate the substance basis of Fubai Chrysanthemum for preventing cataract. The aqueous extracts of Fubaiju mainly contained 39 compounds. Compared with Gongju, Jinsiju and Wild chrysanthemum, Fubai Chrysanthemum showed a higher scavenging rate of 1,1-diphenyl-2-picrylhydrazyl free radicals and higher content of total flavonoid. 14 chemical differences in four kinds of chrysanthemum were found based on principal component difference analysis. Pathway enrichment analysis showed that the main mechanisms of Fubai Chrysanthemum for preventing cataract were affecting the oxidative stress process and regulating cell growth and metabolism. Eventually, 11 key targets of Fubai Chrysanthemum for cataract prevention were identified. The strategy provided a better understanding of the chemical profile of Fubai Chrysanthemum and elucidated that its higher flavonoid content plays an important role in preventing cataract through antioxidant action and regulating cell growth. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Naiyun Cui
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.,School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - Shu Liu
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
| | - Zhong Zheng
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
| | - Zifeng Pi
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.,College of Pharmacy, Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Zhiqiang Liu
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China
| | - Fengrui Song
- State Key Laboratory of Electroanalytical Chemistry, National Center of Mass Spectrometry in Changchun and Jilin Provincal Key Laboratory of Chinese Medicine Chemistry and Mass Spectrometry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.,School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China
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Chen Y, Petrova RS, Qiu C, Donaldson PJ. -Intracellular hydrostatic pressure regulation in the bovine lens: a role in the regulation of lens optics? Am J Physiol Regul Integr Comp Physiol 2022; 322:R263-R279. [PMID: 35107027 DOI: 10.1152/ajpregu.00309.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The optical properties of the bovine lens have been shown to be actively maintained by an internal microcirculation system. In the mouse lens, this water transport through gap junction channels generates an intracellular hydrostatic pressure gradient, which is subjected to a dual feedback regulation that is mediated by the reciprocal modulation of the transient receptor potential vanilloid channels, TRPV1 and TRPV4. Here we test whether a similar feedback regulation of pressure exists in the bovine lens, and whether it regulates overall lens optics. Lens pressure was measured using a microelectrode/pico-injector-based pressure measurement system, and lens optics were monitored in organ cultured lenses using a laser ray tracing system. Like the mouse, the bovine lenses exhibited a similar pressure gradient (0 to 340 mmHg). Activation of TRPV1 with capsaicin caused a biphasic increase in surface pressure, while activation of TRPV4 with GSK1016790A caused a biphasic decrease in pressure. These biphasic responses were abolished if lenses were pre-incubated with either the TRPV1 inhibitor A-889425, or the TRPV4 inhibitor HC-067047. While modulation of lens pressure by TRPV1 and TRPV4 had minimal effects on lens power and overall vision quality, the changes in lens pressure did induce opposing changes to lens geometry and GRIN that effectively kept lens power constant. Hence, our results suggest that the TRPV1/4 mediated feedback control of lens hydrostatic pressure operates to ensure that any fluctuations in lens water transport, and consequently water content, do not result in changes in lens power and therefore overall vision quality.
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Affiliation(s)
- Yadi Chen
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
| | - Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
| | - Chen Qiu
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
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7
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Giannone AA, Li L, Sellitto C, White TW. Physiological Mechanisms Regulating Lens Transport. Front Physiol 2022; 12:818649. [PMID: 35002784 PMCID: PMC8735835 DOI: 10.3389/fphys.2021.818649] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
The transparency and refractive properties of the lens are maintained by the cellular physiology provided by an internal microcirculation system that utilizes spatial differences in ion channels, transporters and gap junctions to establish standing electrochemical and hydrostatic pressure gradients that drive the transport of ions, water and nutrients through this avascular tissue. Aging has negative effects on lens transport, degrading ion and water homeostasis, and producing changes in lens water content. This alters the properties of the lens, causing changes in optical quality and accommodative amplitude that initially result in presbyopia in middle age and ultimately manifest as cataract in the elderly. Recent advances have highlighted that the lens hydrostatic pressure gradient responds to tension transmitted to the lens through the Zonules of Zinn through a mechanism utilizing mechanosensitive channels, multiple sodium transporters respond to changes in hydrostatic pressure to restore equilibrium, and that connexin hemichannels and diverse intracellular signaling cascades play a critical role in these responses. The mechanistic insight gained from these studies has advanced our understanding of lens transport and how it responds and adapts to different inputs both from within the lens, and from surrounding ocular structures.
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Affiliation(s)
- Adrienne A Giannone
- Master of Science Program, Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
| | - Leping Li
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Caterina Sellitto
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Thomas W White
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
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Regulation of the Membrane Trafficking of the Mechanosensitive Ion Channels TRPV1 and TRPV4 by Zonular Tension, Osmotic Stress and Activators in the Mouse Lens. Int J Mol Sci 2021; 22:ijms222312658. [PMID: 34884463 PMCID: PMC8657824 DOI: 10.3390/ijms222312658] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/30/2022] Open
Abstract
Lens water transport generates a hydrostatic pressure gradient that is regulated by a dual-feedback system that utilizes the mechanosensitive transient receptor potential vanilloid (TRPV) channels, TRPV1 and TRPV4, to sense changes in mechanical tension and extracellular osmolarity. Here, we investigate whether the modulation of TRPV1 or TRPV4 activity dynamically affects their membrane trafficking. Mouse lenses were incubated in either pilocarpine or tropicamide to alter zonular tension, exposed to osmotic stress, or the TRPV1 and TRPV4 activators capsaicin andGSK1016790A (GSK101), and the effect on the TRPV1 and TRPV4 membrane trafficking in peripheral fiber cells visualized using confocal microscopy. Decreases in zonular tension caused the removal of TRPV4 from the membrane of peripheral fiber cells. Hypotonic challenge had no effect on TRPV1, but increased the membrane localization of TRPV4. Hypertonic challenge caused the insertion of TRPV1 and the removal of TRPV4 from the membranes of peripheral fiber cells. Capsaicin caused an increase in TRPV4 membrane localization, but had no effect on TRPV1; while GSK101 decreased the membrane localization of TRPV4 and increased the membrane localization of TRPV1. These reciprocal changes in TRPV1/4 membrane localization are consistent with the channels acting as mechanosensitive transducers of a dual-feedback pathway that regulates lens water transport.
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Wang Y, Zhang G, Li P, Kang L, Qin B, Cao Y, Luo J, Chen X, Qin M, Guan H. Profiling and Integrated Analysis of the ERCC6-regulated circRNA-miRNA-mRNA Network in Lens Epithelial Cells. Curr Eye Res 2021; 46:1341-1352. [PMID: 33632032 DOI: 10.1080/02713683.2021.1896742] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Purpose: To explore the regulatory role of ERCC6 in the circRNA-miRNA-mRNA network using a cellular ERCC6 overexpression model (OE-ERCC6) in lens epithelial cells.Methods: The expression profiles of circRNAs, miRNAs and mRNAs were determined by RNA-seq, and a regulatory circRNA-miRNA-mRNA network was constructed via bioinformatics. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used for the functional annotation of circRNA host genes, differentially expressed (DE) genes, and miRNA targets.Results: The DE molecules between the OE-ERCC6 and control groups included 269 circRNAs, 241 miRNAs and 3500 mRNAs. We validated 5 selected DE reads of circRNAs (hsa_circ_0001009, hsa_circ_0002024, hsa_circ_0004592, hsa_circ_0001900 and hsa_circ_0001017). Subsequent bioinformatics analysis revealed that the DE circRNAs are mainly involved in oxidative stress- and cell death-related signaling pathways. Finally, a circRNA-miRNA-mRNA network focusing on DNA damage and cell death, which involved 5 circRNAs, 13 miRNAs and 107 mRNAs, was constructed.Conclusion: We constructed a circRNA-miRNA-mRNA network that is regulated by ERCC6. DE circRNAs have the potential to become therapeutic targets related to the lens lesions observed in ARC. The establishment of related in vivo and in vitro models could be a future direction to confirm these hypotheses.
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Affiliation(s)
- Ying Wang
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Guowei Zhang
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Pengfei Li
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Lihua Kang
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Bai Qin
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Yu Cao
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Jiawei Luo
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Xiaojuan Chen
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Miaomiao Qin
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
| | - Huaijin Guan
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, Jiangsu, China
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Delamere NA, Shahidullah M, Mathias RT, Gao J, Sun X, Sellitto C, White TW. Signaling Between TRPV1/TRPV4 and Intracellular Hydrostatic Pressure in the Mouse Lens. Invest Ophthalmol Vis Sci 2021; 61:58. [PMID: 32598448 PMCID: PMC7415899 DOI: 10.1167/iovs.61.6.58] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The lens uses feedback to maintain zero pressure in its surface cells. Positive pressures are detected by transient receptor potential vanilloid (TRPV4), which initiates a cascade that reduces surface cell osmolarity. The first step is opening of gap junction hemichannels. One purpose of the current study was to identify the connexin(s) in the hemichannels. Negative pressures are detected by TRPV1, which initiates a cascade that increases surface osmolarity. The increase in osmolarity was initially reported to be through inhibition of Na/K ATPase activity, but a recent study reported it was through stimulation of Na/K/2Cl (NKCC) cotransport. A second purpose of this study was to reconcile these two reports. Methods Intracellular hydrostatic pressures were measured using a microelectrode/manometer system. Lenses from TRPV1 or Cx50 null mice were studied. Specific inhibitors of Cx50 gap junction channels, NKCC, and Akt were used. Results Either knockout of Cx50 or blockade of Cx50 channels completely eliminated the response to positive surface pressures. Knockout of Cx50 also caused a positive drift in surface pressure. The short-term (∼20-minute) response to negative surface pressures was eliminated by blockade of NKCC, but a long-term (∼4-hour) response restored pressure to zero. Both short- and long-term responses were eliminated by knockout of TRPV1 or inhibition of Akt. Conclusions Hemichannels made from Cx50 are required for the response to positive surface pressures. Negative surface pressures first activate NKCC, but a backup system is inhibition of Na/K ATPase activity. Both responses are initiated by TRPV1 and go through PI3K/Akt before branching.
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Lens fiber cell differentiation occurs independently of fibroblast growth factor receptor signaling in the absence of Pten. Dev Biol 2020; 467:1-13. [PMID: 32858001 DOI: 10.1016/j.ydbio.2020.07.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 11/21/2022]
Abstract
Fibroblast growth factor receptor (FGFR) signaling patterns multiple tissues in both vertebrates and invertebrates, largely through the activation of intracellular kinases. Recent studies have demonstrated that the phosphatase, PTEN negatively regulates FGFR signaling, such that the loss of PTEN can compensate for reduced FGFR signaling to rescue aspects of normal development. In the developing mouse lens, FGFR signaling promotes cell survival and fiber cell differentiation, and the loss of Pten largely compensates for the loss of Fgfr2 during lens development. To explore this regulatory relationship further, we focused on the phenotypic consequences of Pten loss on lens development and fiber cell differentiation in the absence of all FGFR signaling, both in vivo and in lens epithelial explants. Pten deletion partially rescues primary fiber cell elongation and γ-crystallin accumulation in FGFR-deficient lenses in vivo but fails to rescue cell survival or proliferation. However, in lens epithelial explants, where cells survive without FGFR signaling, Pten deletion rescues vitreous humor-induced lens fiber cell differentiation in the combined absence of Fgfr1, Fgfr2 and Fgfr3. This represents the first evidence that vitreous-initiated signaling cascades, independent of FGFR signaling, can drive mammalian lens fiber cell differentiation, when freed from repression by PTEN.
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Muir ER, Pan X, Donaldson PJ, Vaghefi E, Jiang Z, Sellitto C, White TW. Multi-parametric MRI of the physiology and optics of the in-vivo mouse lens. Magn Reson Imaging 2020; 70:145-154. [PMID: 32380160 DOI: 10.1016/j.mri.2020.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/30/2020] [Accepted: 04/19/2020] [Indexed: 02/07/2023]
Abstract
The optics of the ocular lens are determined by its geometry (shape and volume) and its inherent gradient of refractive index (water to protein ratio), which are in turn maintained by unique cellular physiology known as the lens internal microcirculation system. Previously, magnetic resonance imaging (MRI) has been used on ex vivo organ cultured bovine lenses to show that pharmacological perturbations to this microcirculation system disrupt ionic and fluid homeostasis and overall lens optics. In this study, we have optimised in vivo MRI protocols for use on wild-type and transgenic mouse models so that the effects of genetically perturbing the lens microcirculation system on lens properties can be studied. In vivo MRI protocols and post-analysis methods for studying the mouse lens were optimised and used to measure the lens geometry, diffusion, T1 and T2, as well as the refractive index (n) calculated from T2, in wild-type mice and the genetically modified Cx50KI46 mouse. In this animal line, gap junctional coupling in the lens is increased by knocking in the gap junction protein Cx46 into the Cx50 locus. Relative to wild-type mice, Cx50KI46 mice showed significantly reduced lens size and radius of curvature, increased T1 and T2 values, and decreased n in the lens nucleus, which was consistent with the developmental and functional changes characterised previously in this lens model. These proof of principle experiments show that in vivo MRI can be applied to transgenic mouse models to gain mechanistic insights into the relationship between lens physiology and optics, and in the future suggest that longitudinal studies can be performed to determine how this relationship is altered by age in mouse models of cataract.
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Affiliation(s)
- Eric R Muir
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Xingzheng Pan
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Paul J Donaldson
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand; Department of Physiology, School of Medical Sciences, University of Auckland, New Zealand
| | - Ehsan Vaghefi
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Zhao Jiang
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Caterina Sellitto
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Thomas W White
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, USA.
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13
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Shahidullah M, Mandal A, Mathias RT, Gao J, Križaj D, Redmon S, Delamere NA. TRPV1 activation stimulates NKCC1 and increases hydrostatic pressure in the mouse lens. Am J Physiol Cell Physiol 2020; 318:C969-C980. [PMID: 32293931 PMCID: PMC7294325 DOI: 10.1152/ajpcell.00391.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The porcine lens response to a hyperosmotic stimulus involves an increase in the activity of an ion cotransporter sodium-potassium/two-chloride cotransporter 1 (NKCC1). Recent studies with agonists and antagonists pointed to a mechanism that appears to depend on activation of transient receptor potential vanilloid 1 (TRPV1) ion channels. Here, we compare responses in lenses and cultured lens epithelium obtained from TRPV1-/- and wild type (WT) mice. Hydrostatic pressure (HP) in lens surface cells was determined using a manometer-coupled microelectrode approach. The TRPV1 agonist capsaicin (100 nM) caused a transient HP increase in WT lenses that peaked after ∼30 min and then returned toward baseline. Capsaicin did not cause a detectable change of HP in TRPV1-/- lenses. The NKCC inhibitor bumetanide prevented the HP response to capsaicin in WT lenses. Potassium transport was examined by measuring Rb+ uptake. Capsaicin increased Rb+ uptake in cultured WT lens epithelial cells but not in TRPV1-/- cells. Bumetanide, A889425, and the Akt inhibitor Akti prevented the Rb+ uptake response to capsaicin. The bumetanide-sensitive (NKCC-dependent) component of Rb+ uptake more than doubled in response to capsaicin. Capsaicin also elicited rapid (<2 min) NKCC1 phosphorylation in WT but not TRPV1-/- cells. HP recovery was shown to be absent in TRPV1-/- lenses exposed to hyperosmotic solution. Bumetanide and Akti prevented HP recovery in WT lenses exposed to hyperosmotic solution. Taken together, responses to capsaicin and hyperosmotic solution point to a functional role for TRPV1 channels in mouse lens. Lack of NKCC1 phosphorylation and Rb+ uptake responses in TRPV1-/- mouse epithelium reinforces the notion that a hyperosmotic challenge causes TRPV1-dependent NKCC1 activation. The results are consistent with a role for the TRPV1-activated signaling pathway leading to NKCC1 stimulation in lens osmotic homeostasis.
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Affiliation(s)
- Mohammad Shahidullah
- 1Department of Physiology, University of Arizona, Tucson, Arizona,2Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona
| | - Amritlal Mandal
- 1Department of Physiology, University of Arizona, Tucson, Arizona
| | - Richard T. Mathias
- 3Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York
| | - Junyuan Gao
- 3Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York
| | - David Križaj
- 4Department of Ophthalmology and Vision Science, University of Utah School of Medicine, Salt Lake City, Utah
| | - Sarah Redmon
- 4Department of Ophthalmology and Vision Science, University of Utah School of Medicine, Salt Lake City, Utah
| | - Nicholas A. Delamere
- 1Department of Physiology, University of Arizona, Tucson, Arizona,2Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona
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14
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Chen Y, Gao J, Li L, Sellitto C, Mathias RT, Donaldson PJ, White TW. The Ciliary Muscle and Zonules of Zinn Modulate Lens Intracellular Hydrostatic Pressure Through Transient Receptor Potential Vanilloid Channels. Invest Ophthalmol Vis Sci 2020; 60:4416-4424. [PMID: 31639828 PMCID: PMC6808041 DOI: 10.1167/iovs.19-27794] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Purpose Lenses have an intracellular hydrostatic pressure gradient to drive fluid from central fiber cells to surface epithelial cells. Pressure is regulated by a feedback control system that relies on transient receptor potential vanilloid (TRPV)1 and TRPV4 channels. The ciliary muscle transmits tension to the lens through the zonules of Zinn. Here, we have examined if ciliary muscle tension influenced the lens intracellular hydrostatic pressure gradient. Methods We measured the ciliary body position and intracellular hydrostatic pressures in mouse lenses while pharmacologically causing relaxation or contraction of the ciliary muscle. We also used inhibitors of TRPV1 and TRPV4, in addition to phosphoinositide 3-kinase (PI3K) p110α knockout mice and immunostaining of phosphorylated protein kinase B (Akt), to determine how changes in ciliary muscle tension resulted in altered hydrostatic pressure. Results Ciliary muscle relaxation increased the distance between the ciliary body and the lens and caused a decrease in intracellular hydrostatic pressure that was dependent on intact zonules and could be blocked by inhibition of TRPV4. Ciliary contraction moved the ciliary body toward the lens and caused an increase in intracellular hydrostatic pressure and Akt phosphorylation that required intact zonules and was blocked by either inhibition of TRPV1 or genetic deletion of the p110α catalytic subunit of PI3K. Conclusions These results show that the hydrostatic pressure gradient within the lens was influenced by the tension exerted on the lens by the ciliary muscle through the zonules of Zinn. Modulation of the gradient of intracellular hydrostatic pressure in the lens could alter the water content, and the gradient of refractive index.
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Affiliation(s)
- Yadi Chen
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Junyuan Gao
- Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Leping Li
- Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Caterina Sellitto
- Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Richard T Mathias
- Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Thomas W White
- Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
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15
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Padula SL, Anand D, Hoang TV, Chaffee BR, Liu L, Liang C, Lachke SA, Robinson ML. High-throughput transcriptome analysis reveals that the loss of Pten activates a novel NKX6-1/RASGRP1 regulatory module to rescue microphthalmia caused by Fgfr2-deficient lenses. Hum Genet 2019; 138:1391-1407. [PMID: 31691004 DOI: 10.1007/s00439-019-02084-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/28/2019] [Indexed: 01/17/2023]
Abstract
FGFR signaling is critical to development and disease pathogenesis, initiating phosphorylation-driven signaling cascades, notably the RAS-RAF-MEK-ERK and PI3 K-AKT cascades. PTEN antagonizes FGFR signaling by reducing AKT and ERK activation. Mouse lenses lacking FGFR2 exhibit microphakia and reduced ERK and AKT phosphorylation, widespread apoptosis, and defective lens fiber cell differentiation. In contrast, simultaneous deletion of both Fgfr2 and Pten restores ERK and AKT activation levels as well as lens size, cell survival and aspects of fiber cell differentiation; however, the molecular basis of this "rescue" remains undefined. We performed transcriptomic analysis by RNA sequencing of mouse lenses with conditional deletion of Fgfr2, Pten or both Fgfr2 and Pten, which reveal new molecular mechanisms that uncover how FGFR2 and PTEN signaling interact during development. The FGFR2-deficient lens transcriptome demonstrates overall loss of fiber cell identity with deregulated expression of 1448 genes. We find that ~ 60% of deregulated genes return to normal expression levels in lenses lacking both Fgfr2 and Pten. Further, application of customized filtering parameters to these RNA-seq data sets identified 68 high-priority candidate genes. Bioinformatics analyses showed that the cis-binding motif of a high-priority homeodomain transcription factor, NKX6-1, was present in the putative promoters of ~ 78% of these candidates. Finally, biochemical reporter assays demonstrate that NKX6-1 activated the expression of the high-priority candidate Rasgrp1, a RAS-activating protein. Together, these data define a novel regulatory module in which NKX6-1 directly activates Rasgrp1 expression to restore the balance of ERK and AKT activation, thus providing new insights into alternate regulation of FGFR downstream events.
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Affiliation(s)
| | - Deepti Anand
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Thanh V Hoang
- Department of Biology, Miami University, Oxford, OH, 45056, USA.,Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Blake R Chaffee
- Department of Biology, Miami University, Oxford, OH, 45056, USA
| | - Lin Liu
- Department of Biology, Miami University, Oxford, OH, 45056, USA
| | - Chun Liang
- Department of Biology, Miami University, Oxford, OH, 45056, USA
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, Newark, DE, USA.,Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
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16
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Berthoud VM, Gao J, Minogue PJ, Jara O, Mathias RT, Beyer EC. The Connexin50D47A Mutant Causes Cataracts by Calcium Precipitation. Invest Ophthalmol Vis Sci 2019; 60:2336-2346. [PMID: 31117126 PMCID: PMC6534014 DOI: 10.1167/iovs.18-26459] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Purpose Mutations in connexin50 (Cx50) and connexin46 (Cx46) cause cataracts. Because the expression of Cx46fs380 leads to decreased gap junctional coupling and formation of calcium precipitates, we studied Cx50D47A lenses to test whether Cx50 mutants also cause cataracts due to calcium precipitation. Methods Connexin levels were determined by immunoblotting. Gap junctional coupling conductance was calculated from intracellular impedance studies of intact lenses. Intracellular hydrostatic pressure was measured using a microelectrode/manometer system. Intracellular free calcium ion concentrations ([Ca2+]i) were measured using Fura-2 and fluorescence imaging. Calcium precipitation was assessed by Alizarin red staining and compared to the distribution of opacities in darkfield images. Results In Cx50D47A lenses, Cx50 levels were 11% (heterozygotes) and 1.2% (homozygotes), and Cx46 levels were 52% (heterozygotes) and 30% (homozygotes) when compared to wild-type at 2.5 months. Gap junctional coupling in differentiating fibers of Cx50D47A lenses was 49% (heterozygotes) and 29% (homozygotes), and in mature fibers, it was 24% (heterozygotes) and 4% (homozygotes) compared to wild-type lenses. Hydrostatic pressure was significantly increased in Cx50D47A lenses. [Ca2+]i was significantly increased in Cx50D47A lenses. Alizarin red-stained calcium precipitates were present in homozygous Cx50D47A lenses with a similar distribution to the cataracts. Conclusions Cx50D47A expression altered the lens internal circulation by decreasing connexin levels and gap junctional coupling. Reduced water and ion outflow through gap junctions increased the gradients of intracellular hydrostatic pressure and concentrations of free calcium ions. In these lenses, calcium ions accumulated, precipitated, and formed cataracts. These results suggest that mutant lens fiber connexins lead to calcium precipitates, which may cause cataracts.
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Affiliation(s)
- Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, Illinois, United States
| | - Junyuan Gao
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, United States
| | - Peter J Minogue
- Department of Pediatrics, University of Chicago, Chicago, Illinois, United States
| | - Oscar Jara
- Department of Pediatrics, University of Chicago, Chicago, Illinois, United States
| | - Richard T Mathias
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, United States
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, Illinois, United States
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17
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Xu B, Turner SD, Hinton BT. Alteration of transporter activities in the epididymides of infertile initial segment-specific Pten knockout mice. Biol Reprod 2019; 99:536-545. [PMID: 29590317 DOI: 10.1093/biolre/ioy073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 03/22/2018] [Indexed: 12/24/2022] Open
Abstract
A fully functional initial segment, the most proximal region of the epididymis, is important for male fertility. Our previous study generated a mouse model to investigate the importance of initial segment function in male fertility. In that model, phosphatase and tensin homolog (Pten) was conditionally removed from the initial segment epithelium, which resulted in epithelial de-differentiation. When spermatozoa progressed through the de-differentiated epithelial duct, they developed angled flagella, suggesting compromised sperm maturation, which eventually resulted in male infertility. To understand the molecular mechanisms, by which PTEN regulates epididymal sperm maturation, we compared the transcriptome profile of the initial segment between controls and initial segment-specific Pten knockouts and revealed that water, ion, and organic solute transporter activities were one of the top molecular and cellular functions altered following loss of Pten. Alteration in protein levels and localization of several transporters following loss of Pten were also observed by immunofluorescence analysis. Epithelial cells of the initial segment from knockouts were more permeable to fluorescein isothiocyanate-dextran (4000 Da) compared to controls. Interestingly, conditional deletion of Pten from other organs also resulted in changes in transporter activity, suggesting a common role of PTEN in regulation of transporter activity. Taken together, our data support the hypothesis that loss of Pten from the initial segment epithelium results in changes in the transporting and permeability characteristics of the epithelium, which in turn altered the luminal fluid microenvironment that is so important for sperm maturation and male fertility.
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Affiliation(s)
- Bingfang Xu
- Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, USA
| | - Stephen D Turner
- Bioinformatics Core, University of Virginia Health System, Charlottesville, Virginia, USA
| | - Barry T Hinton
- Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, USA
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18
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Mandal A, Shahidullah M, Delamere NA. TRPV1-dependent ERK1/2 activation in porcine lens epithelium. Exp Eye Res 2018; 172:128-136. [PMID: 29654770 DOI: 10.1016/j.exer.2018.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/21/2018] [Accepted: 04/10/2018] [Indexed: 01/07/2023]
Abstract
Recently we determined that the Transient Receptor Potential Vanilloid 4 ion channel (TRPV4) has a crucial signaling role in a pathway that regulates various aspects of lens epithelium function. Here, we report on a different TRPV channel, TRPV1, in porcine lens. The presence of TRPV1 in the lens was evident from RT-PCR studies and Western blot analysis of MAPK signaling pathway activation caused by the TRPV1 agonist capsaicin. TRPV1 mRNA was detected in the epithelium of porcine as well as human lens. Transient ERK1/2 and p38 MAPK phosphorylation was detected within 1 min in the epithelium isolated from intact porcine lenses exposed to capsaicin (100 nM), a selective TRPV1 agonist, and the response was significantly inhibited by A889245 (1.0 μM), a TRPV1 antagonist. A similar ERK 1/2 and p38 response in the epithelium, also inhibitable by A889245, was evident in lenses treated with hyperosmotic solution (350 vs 300 mOsm). Lenses pre-treated with either the cytosolic Ca2+ chelator BAPTA-AM or the PKC inhibitor sotrastaurin (1.0 μM) had a diminished ERK1/2 activation response to capsaicin and hyperosmotic solution. Taken together the findings support the notion that TRPV1 functions as a plasma membrane ion channel that, when activated, permits the entry of extracellular calcium into the lens epithelium, leading to activation of PKC, ERK1/2 and p38 MAPK. It is significant that the findings confirm earlier proposals that hyperosmotic stress is linked to TRPV1 channel activation in the mouse lens. Further studies are ongoing to determine what functional changes are triggered by the TRPV1-linked signaling pathways and how they might relate to lens volume homeostasis.
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Affiliation(s)
- Amritlal Mandal
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA
| | - Mohammad Shahidullah
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA; Department of Ophthalmology & Vision Science, University of Arizona, Tucson, AZ 85724, USA.
| | - Nicholas A Delamere
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA; Department of Ophthalmology & Vision Science, University of Arizona, Tucson, AZ 85724, USA
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19
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Gao J, Minogue PJ, Beyer EC, Mathias RT, Berthoud VM. Disruption of the lens circulation causes calcium accumulation and precipitates in connexin mutant mice. Am J Physiol Cell Physiol 2018; 314:C492-C503. [PMID: 29351411 PMCID: PMC5966789 DOI: 10.1152/ajpcell.00277.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/26/2017] [Accepted: 12/27/2017] [Indexed: 01/01/2023]
Abstract
The lens is an avascular organ whose function and survival depend on an internal circulation system. Cx46fs380 mice model a human autosomal dominant cataract caused by a mutant lens connexin. In these mice, fiber cell connexin levels and gap junction coupling are severely decreased. The present studies were conducted to examine components of the lens circulation system that might be altered and contribute to the pathogenesis of cataracts. Lenses from wild-type mice and Cx46fs380 heterozygotes and homozygotes were studied at 2 months of age. Cx46fs380-expressing lens fiber cells were depolarized. Cx46fs380 lenses had increased intracellular hydrostatic pressure and concentrations of Na+ and Ca2+. The activity of epithelial Na+-K+-ATPase was decreased in Cx46fs380 lenses. All of these changes were more severe in homozygous than in heterozygous Cx46fs380 lenses. Cx46fs380 cataracts were stained by Alizarin red, a dye used to detect insoluble Ca2+. These data suggest that the lens internal circulation was disrupted by expression of Cx46fs380, leading to several consequences including accumulation of Ca2+ to levels so high that precipitates formed. Similar Ca2+-containing precipitates may contribute to cataract formation due to other genetic or acquired etiologies.
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Affiliation(s)
- Junyuan Gao
- Department of Physiology and Biophysics, Stony Brook University , Stony Brook, New York
| | - Peter J Minogue
- Department of Pediatrics, University of Chicago , Chicago, Illinois
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago , Chicago, Illinois
| | - Richard T Mathias
- Department of Physiology and Biophysics, Stony Brook University , Stony Brook, New York
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20
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Schey KL, Petrova RS, Gletten RB, Donaldson PJ. The Role of Aquaporins in Ocular Lens Homeostasis. Int J Mol Sci 2017; 18:E2693. [PMID: 29231874 PMCID: PMC5751294 DOI: 10.3390/ijms18122693] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 12/13/2022] Open
Abstract
Abstract: Aquaporins (AQPs), by playing essential roles in the maintenance of ocular lens homeostasis, contribute to the establishment and maintenance of the overall optical properties of the lens over many decades of life. Three aquaporins, AQP0, AQP1 and AQP5, each with distinctly different functional properties, are abundantly and differentially expressed in the different regions of the ocular lens. Furthermore, the diversity of AQP functionality is increased in the absence of protein turnover by age-related modifications to lens AQPs that are proposed to alter AQP function in the different regions of the lens. These regional differences in AQP functionality are proposed to contribute to the generation and directionality of the lens internal microcirculation; a system of circulating ionic and fluid fluxes that delivers nutrients to and removes wastes from the lens faster than could be achieved by passive diffusion alone. In this review, we present how regional differences in lens AQP isoforms potentially contribute to this microcirculation system by highlighting current areas of investigation and emphasizing areas where future work is required.
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Affiliation(s)
- Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
| | - Romell B Gletten
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
- School of Optometry and Vison Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
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21
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Functional non-coding polymorphism in an EPHA2 promoter PAX2 binding site modifies expression and alters the MAPK and AKT pathways. Sci Rep 2017; 7:9992. [PMID: 28855599 PMCID: PMC5577203 DOI: 10.1038/s41598-017-10117-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 08/04/2017] [Indexed: 01/11/2023] Open
Abstract
To identify possible genetic variants influencing expression of EPHA2 (Ephrin-receptor Type-A2), a tyrosine kinase receptor that has been shown to be important for lens development and to contribute to both congenital and age related cataract when mutated, the extended promoter region of EPHA2 was screened for variants. SNP rs6603883 lies in a PAX2 binding site in the EPHA2 promoter region. The C (minor) allele decreased EPHA2 transcriptional activity relative to the T allele by reducing the binding affinity of PAX2. Knockdown of PAX2 in human lens epithelial (HLE) cells decreased endogenous expression of EPHA2. Whole RNA sequencing showed that extracellular matrix (ECM), MAPK-AKT signaling pathways and cytoskeleton related genes were dysregulated in EPHA2 knockdown HLE cells. Taken together, these results indicate a functional non-coding SNP in EPHA2 promoter affects PAX2 binding and reduces EPHA2 expression. They further suggest that decreasing EPHA2 levels alters MAPK, AKT signaling pathways and ECM and cytoskeletal genes in lens cells that could contribute to cataract. These results demonstrate a direct role for PAX2 in EPHA2 expression and help delineate the role of EPHA2 in development and homeostasis required for lens transparency.
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22
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Sellitto C, Li L, Vaghefi E, Donaldson PJ, Lin RZ, White TW. The Phosphoinosotide 3-Kinase Catalytic Subunit p110α is Required for Normal Lens Growth. Invest Ophthalmol Vis Sci 2017; 57:3145-51. [PMID: 27304846 PMCID: PMC4928694 DOI: 10.1167/iovs.16-19607] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purpose Signal transduction pathways influence lens growth, but little is known about the role(s) of the class 1A phosphoinositide 3-kinases (PI3Ks). To further investigate how signaling regulates lens growth, we generated and characterized mice in which the p110α and p110β catalytic subunits of PI3K were conditionally deleted in the mouse lens. Methods Floxed alleles of the catalytic subunits of PI3K were conditionally deleted in the lens by using MLR10-cre transgenic mice. Lenses of age-matched animals were dissected and photographed. Postnatal lenses were fixed, paraffin embedded, sectioned, and stained with hematoxylin-eosin. Cell proliferation was quantified by labeling S-phase cells in intact lenses with 5-ethynyl-2′-deoxyuridine. Protein kinase B (AKT) activation was examined by Western blotting. Results Lens-specific deletion of p110α resulted in a significant reduction of eye and lens size, without compromising lens clarity. Conditional knockout of p110β had no effect on lens size or clarity, and deletion of both the p110α and p110β subunits resulted in a phenotype that resembled the p110α single-knockout phenotype. Levels of activated AKT were decreased more in p110α- than in p110β-deficient lenses. A significant reduction in proliferating cells in the germinative zone was observed on postnatal day 0 in p110α knockout mice, which was temporally correlated with decreased lens volume. Conclusions These data suggest that the class 1A PI3K signaling pathway plays an important role in the regulation of lens size by influencing the extent and spatial location of cell proliferation in the perinatal period.
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Affiliation(s)
- Caterina Sellitto
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
| | - Leping Li
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
| | - Ehsan Vaghefi
- School of Optometry and Vision Science, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Richard Z Lin
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States 4Medical Service, Department of Veterans Affairs Medical Center, Northport, New York, United States
| | - Thomas W White
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
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Abstract
The lens is an avascular organ composed of an anterior epithelial cell layer and fiber cells that form the bulk of the organ. The lens expresses connexin43 (Cx43), connexin46 (Cx46) and connexin50 (Cx50). Epithelial Cx50 has critical roles in cell proliferation and differentiation, likely involving growth factor-dependent signaling pathways. Both Cx46 and Cx50 are crucial for lens transparency; mutations in their genes have been linked to congenital and age-related cataracts. Congenital cataract-associated connexin mutants can affect protein trafficking, stability and/or function, and the functional effects may differ between gap junction channels and hemichannels. Dominantly inherited cataracts may result from effects of the connexin mutant on its wild type isotype, the other co-expressed wild type connexin and/or its interaction with other cellular components.
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Affiliation(s)
| | - Anaclet Ngezahayo
- Institute of Biophysics, Leibniz University Hannover, Hannover, Germany.
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Donaldson PJ, Grey AC, Maceo Heilman B, Lim JC, Vaghefi E. The physiological optics of the lens. Prog Retin Eye Res 2017; 56:e1-e24. [DOI: 10.1016/j.preteyeres.2016.09.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/09/2016] [Accepted: 09/13/2016] [Indexed: 11/17/2022]
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25
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Gao J, Sun X, White TW, Delamere NA, Mathias RT. Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens. Biophys J 2016; 109:1830-9. [PMID: 26536260 DOI: 10.1016/j.bpj.2015.09.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 09/08/2015] [Accepted: 09/16/2015] [Indexed: 10/22/2022] Open
Abstract
In wild-type lenses from various species, an intracellular hydrostatic pressure gradient goes from ∼340 mmHg in central fiber cells to 0 mmHg in surface cells. This gradient drives a center-to-surface flow of intracellular fluid. In lenses in which gap-junction coupling is increased, the central pressure is lower, whereas if gap-junction coupling is reduced, the central pressure is higher but surface pressure is always zero. Recently, we found that surface cell pressure was elevated in PTEN null lenses. This suggested disruption of a feedback control system that normally maintained zero surface cell pressure. Our purpose in this study was to investigate and characterize this feedback control system. We measured intracellular hydrostatic pressures in mouse lenses using a microelectrode/manometer-based system. We found that all feedback went through transport by the Na/K ATPase, which adjusted surface cell osmolarity such that pressure was maintained at zero. We traced the regulation of Na/K ATPase activity back to either TRPV4, which sensed positive pressure and stimulated activity, or TRPV1, which sensed negative pressure and inhibited activity. The inhibitory effect of TRPV1 on Na/K pumps was shown to signal through activation of the PI3K/AKT axis. The stimulatory effect of TRPV4 was shown in previous studies to go through a different signal transduction path. Thus, there is a local two-legged feedback control system for pressure in lens surface cells. The surface pressure provides a pedestal on which the pressure gradient sits, so surface pressure determines the absolute value of pressure at each radial location. We speculate that the absolute value of intracellular pressure may set the radial gradient in the refractive index, which is essential for visual acuity.
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Affiliation(s)
- Junyuan Gao
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York
| | - Xiurong Sun
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York
| | - Nicholas A Delamere
- Department of Physiology and Biophysics, University of Arizona, Tucson, Arizona
| | - Richard T Mathias
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York.
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Chaffee BR, Hoang TV, Leonard MR, Bruney DG, Wagner BD, Dowd JR, Leone G, Ostrowski MC, Robinson ML. FGFR and PTEN signaling interact during lens development to regulate cell survival. Dev Biol 2016; 410:150-163. [PMID: 26764128 DOI: 10.1016/j.ydbio.2015.12.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 12/31/2015] [Accepted: 12/31/2015] [Indexed: 12/13/2022]
Abstract
Lens epithelial cells express many receptor tyrosine kinases (RTKs) that stimulate PI3K-AKT and RAS-RAF-MEK-ERK intracellular signaling pathways. These pathways ultimately activate the phosphorylation of key cellular transcription factors and other proteins that control proliferation, survival, metabolism, and differentiation in virtually all cells. Among RTKs in the lens, only stimulation of fibroblast growth factor receptors (FGFRs) elicits a lens epithelial cell to fiber cell differentiation response in mammals. Moreover, although the lens expresses three different Fgfr genes, the isolated removal of Fgfr2 at the lens placode stage inhibits both lens cell survival and fiber cell differentiation. Phosphatase and tensin homolog (PTEN), commonly known as a tumor suppressor, inhibits ERK and AKT activation and initiates both apoptotic pathways, and cell cycle arrest. Here, we show that the combined deletion of Fgfr2 and Pten rescues the cell death phenotype associated with Fgfr2 loss alone. Additionally, Pten removal increased AKT and ERK activation, above the levels of controls, in the presence or absence of Fgfr2. However, isolated deletion of Pten failed to stimulate ectopic fiber cell differentiation, and the combined deletion of Pten and Fgfr2 failed to restore differentiation-specific Aquaporin0 and DnaseIIβ expression in the lens fiber cells.
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Affiliation(s)
- Blake R Chaffee
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Thanh V Hoang
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Melissa R Leonard
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Devin G Bruney
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Brad D Wagner
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Joseph Richard Dowd
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA
| | - Gustavo Leone
- Department of Molecular Virology, Immunology and Medical Genetics, Department of Molecular Genetics, The Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA
| | - Michael C Ostrowski
- Department of Molecular Virology, Immunology and Medical Genetics, Department of Molecular Genetics, The Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA
| | - Michael L Robinson
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, USA.
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Mroske C, Rasmussen K, Shinde DN, Huether R, Powis Z, Lu HM, Baxter RM, McPherson E, Tang S. Germline activating MTOR mutation arising through gonadal mosaicism in two brothers with megalencephaly and neurodevelopmental abnormalities. BMC MEDICAL GENETICS 2015; 16:102. [PMID: 26542245 PMCID: PMC4635597 DOI: 10.1186/s12881-015-0240-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/03/2015] [Indexed: 01/06/2023]
Abstract
Background In humans, Mammalian Target of Rapamycin (MTOR) encodes a 300 kDa serine/ threonine protein kinase that is ubiquitously expressed, particularly at high levels in brain. MTOR functions as an integrator of multiple cellular processes, and in so doing either directly or indirectly regulates the phosphorylation of at least 800 proteins. While somatic MTOR mutations have been recognized in tumors for many years, and more recently in hemimegalencephaly, germline MTOR mutations have rarely been described. Case presentation We report the successful application of family-trio Diagnostic Exome Sequencing (DES) to identify the underlying molecular etiology in two brothers with multiple neurological and developmental lesions, and for whom previous testing was non-diagnostic. The affected brothers, who were 6 and 23 years of age at the time of DES, presented symptoms including but not limited to mild Autism Spectrum Disorder (ASD), megalencephaly, gross motor skill delay, cryptorchidism and bilateral iris coloboma. Importantly, we determined that each affected brother harbored the MTOR missense alteration p.E1799K (c.5395G>A). This exact variant has been previously identified in multiple independent human somatic cancer samples and has been shown to result in increased MTOR activation. Further, recent independent reports describe two unrelated families in whom p.E1799K co-segregated with megalencephaly and intellectual disability (ID); in both cases, p.E1799K was shown to have originated due to germline mosaicism. In the case of the family reported herein, the absence of p.E1799K in genomic DNA extracted from the blood of either parent suggests that this alteration most likely arose due to gonadal mosaicism. Further, the p.E1799K variant exerts its effect by a gain-of-function (GOF), autosomal dominant mechanism. Conclusion Herein, we describe the use of DES to uncover an activating MTOR missense alteration of gonadal mosaic origin that is likely to be the causative mutation in two brothers who present multiple neurological and developmental abnormalities. Our report brings the total number of families who harbor MTOR p.E1799K in association with megalencephaly and ID to three. In each case, evidence suggests that p.E1799K arose in the affected individuals due to gonadal mosaicism. Thus, MTOR p.E1799K can now be classified as a pathogenic GOF mutation that causes megalencephaly and cognitive impairment in humans. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0240-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cameron Mroske
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | | | | | - Robert Huether
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Zoe Powis
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Hsiao-Mei Lu
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | - Ruth M Baxter
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
| | | | - Sha Tang
- Ambry Genetics Corporation, Aliso Viejo, CA, 92656, USA.
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Hamada N, Fujimichi Y. Role of carcinogenesis related mechanisms in cataractogenesis and its implications for ionizing radiation cataractogenesis. Cancer Lett 2015; 368:262-74. [DOI: 10.1016/j.canlet.2015.02.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 12/20/2022]
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Martinez JM, Wang HZ, Lin RZ, Brink PR, White TW. Differential regulation of Connexin50 and Connexin46 by PI3K signaling. FEBS Lett 2015; 589:1340-5. [PMID: 25935417 PMCID: PMC4433579 DOI: 10.1016/j.febslet.2015.04.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/06/2015] [Accepted: 04/16/2015] [Indexed: 01/28/2023]
Abstract
Gap junction channels can modify their activity in response to cell signaling pathways. Here, we demonstrate that Connexin50 (Cx50) coupling, but not Connexin46 (Cx46), increased when co-expressed with a constitutively active p110α subunit of PI3K in Xenopus oocytes. In addition, inhibition of PI3K signaling by blocking p110α, or Akt, significantly decreased gap junctional conductance in Cx50 transfected HeLa cells, with no effect on Cx46. Alterations in coupling levels were not a result of reduced Cx50 unitary conductance, suggesting that changes in the number of active channels were responsible. These data indicate that Cx50 is specifically regulated by the PI3K signaling pathway.
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Affiliation(s)
- Jennifer M Martinez
- The Department of Physiology & Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Hong-Zhan Wang
- The Department of Physiology & Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Richard Z Lin
- The Department of Physiology & Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Peter R Brink
- The Department of Physiology & Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Thomas W White
- The Department of Physiology & Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA.
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