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Ek-Vitorin JF, Shahidullah M, Lopez Rosales JE, Delamere NA. Patch clamp studies on TRPV4-dependent hemichannel activation in lens epithelium. Front Pharmacol 2023; 14:1101498. [PMID: 36909173 PMCID: PMC9998544 DOI: 10.3389/fphar.2023.1101498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/06/2023] [Indexed: 02/26/2023] Open
Abstract
ATP release from the lens via hemichannels has been explained as a response to TRPV4 activation when the lens is subjected to osmotic swelling. To explore the apparent linkage between TRPV4 activation and connexin hemichannel opening we performed patch-clamp recordings on cultured mouse lens epithelial cells exposed to the TRPV4 agonist GSK1016790A (GSK) in the presence or absence of the TRPV4 antagonist HC067047 (HC). GSK was found to cause a fast, variable and generally large non-selective increase of whole cell membrane conductance evident as a larger membrane current (Im) over a wide voltage range. The response was prevented by HC. The GSK-induced Im increase was proportionally larger at negative voltages and coincided with fast depolarization and the simultaneous disappearance of an outward current, likely a K+ current. The presence of this outward current in control conditions appeared to be a reliable predictor of a cell's response to GSK treatment. In some studies, recordings were obtained from single cells by combining cell-attached and whole-cell patch clamp configurations. This approach revealed events with a channel conductance 180-270 pS following GSK application through the patch pipette on the cell-attached side. The findings are consistent with TRPV4-dependent opening of Cx43 hemichannels.
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Affiliation(s)
- Jose F Ek-Vitorin
- Department of Physiology, University of Arizona, Tucson, AZ, United States
| | - Mohammad Shahidullah
- Department of Physiology, University of Arizona, Tucson, AZ, United States.,Department of Ophthalmology and Vision Science, University of Arizona, Tucson, AZ, United States
| | | | - Nicholas A Delamere
- Department of Physiology, University of Arizona, Tucson, AZ, United States.,Department of Ophthalmology and Vision Science, University of Arizona, Tucson, AZ, United States
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Cantrell LS, Gletten RB, Schey KL. Proteome Remodeling of the Eye Lens at 50 Years Identified With Data-Independent Acquisition. Mol Cell Proteomics 2022; 22:100453. [PMID: 36470534 PMCID: PMC9800634 DOI: 10.1016/j.mcpro.2022.100453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 11/03/2022] [Accepted: 11/20/2022] [Indexed: 12/12/2022] Open
Abstract
The eye lens is responsible for focusing and transmitting light to the retina. The lens does this in the absence of organelles, yet maintains transparency for at least 5 decades before onset of age-related nuclear cataract (ARNC). It is hypothesized that oxidative stress contributes significantly to ARNC formation. It is in addition hypothesized that transparency is maintained by a microcirculation system that delivers antioxidants to the lens nucleus and exports small molecule waste. Common data-dependent acquisition methods are hindered by dynamic range of lens protein expression and provide limited context to age-related changes in the lens. In this study, we utilized data-independent acquisition mass spectrometry to analyze the urea-insoluble membrane protein fractions of 16 human lenses subdivided into three spatially distinct lens regions to characterize age-related changes, particularly concerning the lens microcirculation system and oxidative stress response. In this pilot cohort, we measured 4788 distinct protein groups, 46,681 peptides, and 7592 deamidated sequences, more than in any previous human lens data-dependent acquisition approach. Principally, we demonstrate that a significant proteome remodeling event occurs at approximately 50 years of age, resulting in metabolic preference for anaerobic glycolysis established with organelle degradation, decreased abundance of protein networks involved in calcium-dependent cell-cell contacts while retaining networks related to oxidative stress response. Furthermore, we identified multiple antioxidant transporter proteins not previously detected in the human lens and describe their spatiotemporal and age-related abundance changes. Finally, we demonstrate that aquaporin-5, among other proteins, is modified with age by post-translational modifications including deamidation and truncation. We suggest that the continued accumulation of each of these age-related outcomes in proteome remodeling contribute to decreased fiber cell permeability and result in ARNC formation.
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Affiliation(s)
- Lee S. Cantrell
- Vanderbilt University Mass Spectrometry Research Center, Nashville, Tennessee, USA,Vanderbilt University Chemical and Physical Biology Program, Nashville, Tennessee, USA
| | - Romell B. Gletten
- Vanderbilt University Mass Spectrometry Research Center, Nashville, Tennessee, USA,Vanderbilt University Department of Biochemistry, Nashville, Tennessee, USA
| | - Kevin L. Schey
- Vanderbilt University Mass Spectrometry Research Center, Nashville, Tennessee, USA,Vanderbilt University Chemical and Physical Biology Program, Nashville, Tennessee, USA,Vanderbilt University Department of Biochemistry, Nashville, Tennessee, USA,For correspondence: Kevin L. Schey
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Valiunas V, Gordon C, Valiuniene L, Devine D, Lin RZ, Cohen IS, Brink PR. Intercellular delivery of therapeutic oligonucleotides. J Drug Deliv Sci Technol 2022; 72:103404. [PMID: 36721641 PMCID: PMC9886232 DOI: 10.1016/j.jddst.2022.103404] [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] [Indexed: 02/03/2023]
Abstract
One promising approach to cancer therapeutics is to induce changes in gene expression that either reduce cancer cell proliferation or induce cancer cell death. Therefore, delivering oligonucleotides (siRNA/miRNA) that target specific genes or gene programs might have a potential therapeutic benefit. The aim of this study was to examine the potential of cell-based delivery of oligonucleotides to cancer cells via two naturally occurring intercellular pathways: gap junctions and vesicular/exosomal traffic. We utilized human mesenchymal stem cells (hMSCs) as delivery cells and chose to deliver in vitro two synthetic oligonucleotides, AllStars HS Cell Death siRNA and miR-16 mimic, as toxic (therapeutic) oligonucleotides targeting three cancer cell lines: prostate (PC3), pancreatic (PANC1) and cervical (HeLa). Both oligonucleotides dramatically reduced cell proliferation and/or induced cell death when transfected directly into target cells and delivery hMSCs. The delivery and target cells we chose express gap junction connexin 43 (Cx43) endogenously (PC3, PANC1, hMSC) or via stable transfection (HeLaCx43). Co-culture of hMSCs (transfected with either toxic oligonucleotide) with any of Cx43 expressing cancer cells induced target cell death (~20% surviving) or senescence (~85% proliferation reduction) over 96 hours. We eliminated gap junction-mediated delivery by using connexin deficient HeLaWT cells or knocking out endogenous Cx43 in PANC1 and PC3 cells via CRISPR/Cas9. Subsequently, all Cx43 deficient target cells co-cultured with the same toxic oligonucleotide loaded hMSCs proliferated, albeit at significantly slower rates, with cell number increasing on average ~2.2-fold (30% of control cells) over 96 hours. Our results show that both gap junction and vesicular/exosomal intercellular delivery pathways from hMSCs to target cancer cells deliver oligonucleotides and function to either induce cell death or significantly reduce their proliferation. Thus, hMSC-based cellular delivery is an effective method of delivering synthetic oligonucleotides that can significantly reduce tumor cell growth and should be further investigated as a possible approach to cancer therapy.
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Affiliation(s)
- Virginijus Valiunas
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Chris Gordon
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Laima Valiuniene
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Daniel Devine
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Richard Z Lin
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Ira S Cohen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Peter R Brink
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology Stony Brook University, Stony Brook, NY 11794-8661, USA
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Shi Y, Li X, Yang J. Mutations of CX46/CX50 and Cataract Development. Front Mol Biosci 2022; 9:842399. [PMID: 35223995 PMCID: PMC8874012 DOI: 10.3389/fmolb.2022.842399] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 01/12/2022] [Indexed: 12/24/2022] Open
Abstract
Cataract is a common disease in the aging population. Gap junction has been considered a central component in maintaining homeostasis for preventing cataract formation. Gap junction channels consist of connexin proteins with more than 20 members. Three genes including GJA1, GJA3, and GJA8, that encode protein Cx43 (connexin43), Cx46 (connexin46), and Cx50 (connexin50), respectively, have been identified in human and rodent lens. Cx46 together with Cx50 have been detected in lens fiber cells with high expression, whereas Cx43 is mainly expressed in lens epithelial cells. Disrupted expression of the two connexin proteins Cx46 and Cx50 is directly related to the development of severe cataract in human and mice. In this review article, we describe the main role of Cx46 and Cx50 connexin proteins in the lens and the relationship between mutations of Cx46 or Cx50 and hereditary cataracts. Furthermore, the latest progress in the fundamental research of lens connexin and the mechanism of cataract formation caused by lens connexin dysfunction are summarized. Overall, targeting connexin could be a novel approach for the treatment of cataract.
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Affiliation(s)
- Yumeng Shi
- Key Laboratory of Visual Impairment and Restoration of Shanghai, Department of Ophthalmology and Visual Science, Eye Ear Nose and Throat Hospital of Fudan University, Shanghai, China
| | - Xinbo Li
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, United States
- *Correspondence: Jin Yang, ; Xinbo Li,
| | - Jin Yang
- Key Laboratory of Visual Impairment and Restoration of Shanghai, Department of Ophthalmology and Visual Science, Eye Ear Nose and Throat Hospital of Fudan University, Shanghai, China
- *Correspondence: Jin Yang, ; Xinbo Li,
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Ahmed MA, Venugopal S, Jung R. Engaging biological oscillators through second messenger pathways permits emergence of a robust gastric slow-wave during peristalsis. PLoS Comput Biol 2021; 17:e1009644. [PMID: 34871315 PMCID: PMC8675931 DOI: 10.1371/journal.pcbi.1009644] [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: 06/19/2021] [Revised: 12/16/2021] [Accepted: 11/15/2021] [Indexed: 11/19/2022] Open
Abstract
Peristalsis, the coordinated contraction—relaxation of the muscles of the stomach is important for normal gastric motility and is impaired in motility disorders. Coordinated electrical depolarizations that originate and propagate within a network of interconnected layers of interstitial cells of Cajal (ICC) and smooth muscle (SM) cells of the stomach wall as a slow-wave, underly peristalsis. Normally, the gastric slow-wave oscillates with a single period and uniform rostrocaudal lag, exhibiting network entrainment. Understanding of the integrative role of neurotransmission and intercellular coupling in the propagation of an entrained gastric slow-wave, important for understanding motility disorders, however, remains incomplete. Using a computational framework constituted of a novel gastric motility network (GMN) model we address the hypothesis that engaging biological oscillators (i.e., ICCs) by constitutive gap junction coupling mechanisms and enteric neural innervation activated signals can confer a robust entrained gastric slow-wave. We demonstrate that while a decreasing enteric neural innervation gradient that modulates the intracellular IP3 concentration in the ICCs can guide the aboral slow-wave propagation essential for peristalsis, engaging ICCs by recruiting the exchange of second messengers (inositol trisphosphate (IP3) and Ca2+) ensures a robust entrained longitudinal slow-wave, even in the presence of biological variability in electrical coupling strengths. Our GMN with the distinct intercellular coupling in conjunction with the intracellular feedback pathways and a rostrocaudal enteric neural innervation gradient allows gastric slow waves to oscillate with a moderate range of frequencies and to propagate with a broad range of velocities, thus preventing decoupling observed in motility disorders. Overall, the findings provide a mechanistic explanation for the emergence of decoupled slow waves associated with motility impairments of the stomach, offer directions for future experiments and theoretical work, and can potentially aid in the design of new interventional pharmacological and neuromodulation device treatments for addressing gastric motility disorders. The coordinated contraction and relaxation of the muscles of the stomach, known as peristalsis is important for normal gastric motility and primarily governed by electrical depolarizations that originate and propagate within a network of interconnected layers of interstitial cells of Cajal (ICCs) and smooth muscle cells of the stomach wall as a slow-wave. Under normal conditions, a gastric slow-wave oscillates with a single period and uniform rostrocaudal lag, exhibiting network entrainment. However, the understanding of intrinsic and extrinsic mechanisms that ensure propagation of a robust entrained slow-wave remains incomplete. Here, using a computational framework, we show that in conjunction with an enteric neural innervation gradient along the rostrocaudal ICC chain, and intercellular electrical coupling, the intercellular exchange of inositol trisphosphate between ICCs prevents decoupling by extending the longitudinal entrainment range along the stomach wall, even when variability in intercellular coupling exists. The findings from our study indicate ways that ensure the rostrocaudal spread of a robust gastric slow-wave and provide a mechanistic explanation for the emergence of decoupled slow waves associated with motility impairments of the stomach.
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Affiliation(s)
- Md Ashfaq Ahmed
- Department of Biomedical Engineering, Florida International University, Miami, Florida, United States of America
| | - Sharmila Venugopal
- Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (SV); (RJ)
| | - Ranu Jung
- Department of Biomedical Engineering, Florida International University, Miami, Florida, United States of America
- * E-mail: (SV); (RJ)
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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Brink PR, Valiunas V, White TW. Lens Connexin Channels Show Differential Permeability to Signaling Molecules. Int J Mol Sci 2020; 21:ijms21186943. [PMID: 32971763 PMCID: PMC7555617 DOI: 10.3390/ijms21186943] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 12/12/2022] Open
Abstract
Gap junction channels mediate the direct intercellular passage of small ions as well as larger solutes such as second messengers. A family of proteins called connexins make up the subunits of gap junction channels in chordate animals. Each individual connexin forms channels that exhibit distinct permeability to molecules that influence cellular signaling, such as calcium ions, cyclic nucleotides, or inositol phosphates. In this review, we examine the permeability of connexin channels containing Cx43, Cx46, and Cx50 to signaling molecules and attempt to relate the observed differences in permeability to possible in vivo consequences that were revealed by studies of transgenic animals where these connexin genes have been manipulated. Taken together, these data suggest that differences in the permeability of individual connexin channels to larger solutes like 3',5'-cyclic adenosine monophosphate (cAMP) and inositol 1,4,5-trisphosphate (IP3) could play a role in regulating epithelial cell division, differentiation, and homeostasis in organs like the ocular lens.
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