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Fu H, Siggs OM, Knight LS, Staffieri SE, Ruddle JB, Birsner AE, Collantes ER, Craig JE, Wiggs JL, D’Amato RJ. Thrombospondin 1 missense alleles induce extracellular matrix protein aggregation and TM dysfunction in congenital glaucoma. J Clin Invest 2022; 132:156967. [PMID: 36453543 PMCID: PMC9711877 DOI: 10.1172/jci156967] [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: 11/23/2021] [Accepted: 10/11/2022] [Indexed: 12/03/2022] Open
Abstract
Glaucoma is a highly heritable disease that is a leading cause of blindness worldwide. Here, we identified heterozygous thrombospondin 1 (THBS1) missense alleles altering p.Arg1034, a highly evolutionarily conserved amino acid, in 3 unrelated and ethnically diverse families affected by congenital glaucoma, a severe form of glaucoma affecting children. Thbs1R1034C-mutant mice had elevated intraocular pressure (IOP), reduced ocular fluid outflow, and retinal ganglion cell loss. Histology revealed an abundant, abnormal extracellular accumulation of THBS1 with abnormal morphology of juxtacanalicular trabecular meshwork (TM), an ocular tissue critical for aqueous fluid outflow. Functional characterization showed that the THBS1 missense alleles found in affected individuals destabilized the THBS1 C-terminus, causing protein misfolding and extracellular aggregation. Analysis using a range of amino acid substitutions at position R1034 showed that the extent of aggregation was correlated with the change in protein-folding free energy caused by variations in amino acid structure. Extracellular matrix (ECM) proteins, especially fibronectin, which bind to THBS1, also accumulated within THBS1 deposits. These results show that missense variants altering THBS1 p.Arg1034 can cause elevated IOP through a mechanism involving impaired TM fluid outflow in association with accumulation of aggregated THBS1 in the ECM of juxtacanalicular meshwork with altered morphology.
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Affiliation(s)
- Haojie Fu
- Vascular Biology Program, Department of Surgery, Boston Children’s Hospital, Boston, Massachusetts, USA.,Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Owen M. Siggs
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia.,Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Lachlan S.W. Knight
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Sandra E. Staffieri
- Centre for Eye Research Australia (CERA), Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.,Department of Ophthalmology, University of Melbourne, Department of Surgery, Parkville, Victoria, Australia.,Department of Ophthalmology, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Jonathan B. Ruddle
- Department of Ophthalmology, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Amy E. Birsner
- Vascular Biology Program, Department of Surgery, Boston Children’s Hospital, Boston, Massachusetts, USA
| | | | - Jamie E. Craig
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Janey L. Wiggs
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Ophthalmology, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Boston, Massachusetts, USA
| | - Robert J. D’Amato
- Vascular Biology Program, Department of Surgery, Boston Children’s Hospital, Boston, Massachusetts, USA.,Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
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MacDonald WW, Swaminathan SS, Heo JY, Castillejos A, Hsueh J, Liu BJ, Jo D, Du A, Lee H, Kang MH, Rhee DJ. Effect of SPARC Suppression in Mice, Perfused Human Anterior Segments, and Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2022; 63:8. [PMID: 35671048 PMCID: PMC9187959 DOI: 10.1167/iovs.63.6.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose Secreted protein, acidic and rich in cysteine (SPARC) elevates intraocular pressure (IOP), increases certain structural extracellular matrix (ECM) proteins in the juxtacanalicular trabecular meshwork (JCT), and decreases matrix metalloproteinase (MMP) protein levels in trabecular meshwork (TM) endothelial cells. We investigated SPARC as a potential target for lowering IOP. We hypothesized that suppressing SPARC will decrease IOP, decrease structural JCT ECM proteins, and alter the levels of MMPs and/or their inhibitors. Methods A lentivirus containing short hairpin RNA of human SPARC suppressed SPARC in mouse eyes and perfused cadaveric human anterior segments with subsequent IOP measurements. Immunohistochemistry determined structural correlates. Human TM cell cultures were treated with SPARC suppressing lentivirus. Quantitative reverse transcriptase polymerase chain reaction (PCR), immunoblotting, and zymography determined total RNA, relative protein levels, and MMP enzymatic activity, respectively. Results Suppressing SPARC decreased IOP in mouse eyes and perfused human anterior segments by approximately 20%. Histologically, this correlated to a decrease in collagen I, IV, and VI in both the mouse TM and human JCT regions; in the mouse, fibronectin was also decreased but not in the human. In TM cells, collagen I and IV, fibronectin, MMP-2, and tissue inhibitor of MMP-1 were decreased. Messenger RNA of the aforementioned genes was not changed. Plasminogen activator inhibitor 1 (PAI-1) was upregulated in vitro by quantitative PCR and immunoblotting. MMP-1 activity was reduced in vitro by zymography. Conclusions Suppressing SPARC decreased IOP in mice and perfused cadaveric human anterior segments corresponding to qualitative structural changes in the JCT ECM, which do not appear to be the result of transcription regulation.
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Affiliation(s)
- William W MacDonald
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Swarup S Swaminathan
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States.,Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, Florida, United States
| | - Jae Young Heo
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Alexandra Castillejos
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States.,Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Boston, Massachusetts, United States
| | - Jessica Hsueh
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Brian J Liu
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Diane Jo
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Annie Du
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Hyunpil Lee
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Min Hyung Kang
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Douglas J Rhee
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
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Murphy-Ullrich JE. Thrombospondin-1 Signaling Through the Calreticulin/LDL Receptor Related Protein 1 Axis: Functions and Possible Roles in Glaucoma. Front Cell Dev Biol 2022; 10:898772. [PMID: 35693935 PMCID: PMC9185677 DOI: 10.3389/fcell.2022.898772] [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: 03/17/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Thrombospondin-1 (TSP-1) is a matricellular extracellular matrix protein. Matricellular proteins are components of the extracellular matrix (ECM) that regulate key cellular functions and impact ECM organization, but which lack direct primary structural roles in the ECM. TSP-1 expression is upregulated in response to injury, hypoxia, growth factor stimulation, inflammation, glucose, and by reactive oxygen species. Relevant to glaucoma, TSP-1 is also a mechanosensitive molecule upregulated by mechanical stretch. TSP-1 expression is increased in ocular remodeling in glaucoma in both the trabecular meshwork and in the optic nerve head. The exact roles of TSP-1 in glaucoma remain to be defined, however. It plays important roles in cell behavior and in ECM remodeling during wound healing, fibrosis, angiogenesis, and in tumorigenesis and metastasis. At the cellular level, TSP-1 can modulate cell adhesion and migration, protease activity, growth factor activity, anoikis resistance, apoptosis, and collagen secretion and matrix assembly and cross-linking. These multiple functions and macromolecular and receptor interactions have been ascribed to specific domains of the TSP-1 molecule. In this review, we will focus on the cell regulatory activities of the TSP-1 N-terminal domain (NTD) sequence that binds to cell surface calreticulin (Calr) and which regulates cell functions via signaling through Calr complexed with LDL receptor related protein 1 (LRP1). We will describe TSP-1 actions mediated through the Calr/LRP1 complex in regulating focal adhesion disassembly and cytoskeletal reorganization, cell motility, anoikis resistance, and induction of collagen secretion and matrix deposition. Finally, we will consider the relevance of these TSP-1 functions to the pathologic remodeling of the ECM in glaucoma.
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Affiliation(s)
- Joanne E. Murphy-Ullrich
- Departments of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, United States
- *Correspondence: Joanne E. Murphy-Ullrich,
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Yang YF, Sun YY, Peters DM, Keller KE. The Effects of Mechanical Stretch on Integrins and Filopodial-Associated Proteins in Normal and Glaucomatous Trabecular Meshwork Cells. Front Cell Dev Biol 2022; 10:886706. [PMID: 35573666 PMCID: PMC9100841 DOI: 10.3389/fcell.2022.886706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/11/2022] [Indexed: 01/29/2023] Open
Abstract
The trabecular meshwork (TM) is the tissue responsible for regulating aqueous humor fluid egress from the anterior eye. If drainage is impaired, intraocular pressure (IOP) becomes elevated, which is a primary risk factor for primary open angle glaucoma. TM cells sense elevated IOP via changes in their biomechanical environment. Filopodia cellular protrusions and integrin transmembrane proteins may play roles in detecting IOP elevation, yet this has not been studied in detail in the TM. Here, we investigate integrins and filopodial proteins, such as myosin-X (Myo10), in response to mechanical stretch, an in vitro technique that produces mechanical alterations mimicking elevated IOP. Pull-down assays showed Myo10 binding to α5 but not the β1 subunit, αvβ3, and αvβ5 integrins. Several of these integrins colocalized in nascent adhesions in the filopodial tip and shaft. Using conformation-specific antibodies, we found that β1 integrin, but not α5 or αvβ3 integrins, were activated following 1-h mechanical stretch. Cadherin -11 (CDH11), a cell adhesion molecule, did not bind to Myo10, but was associated with filopodia. Interestingly, CDH11 was downregulated on the TM cell surface following 1-h mechanical stretch. In glaucoma cells, CDH11 protein levels were increased. Finally, mechanical stretch caused a small, yet significant increase in Myo10 protein levels in glaucoma cells, but did not affect cellular communication of fluorescent vesicles via filopodia-like tunneling nanotubes. Together, these data suggest that TM cell adhesion proteins, β1 integrin and CDH11, have relatively rapid responses to mechanical stretch, which suggests a central role in sensing changes in IOP elevation in situ.
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Affiliation(s)
- Yong-Feng Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Ying Ying Sun
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States
| | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, United States,Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, United States,*Correspondence: Kate E. Keller,
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Keller KE, Peters DM. Pathogenesis of glaucoma: Extracellular matrix dysfunction in the trabecular meshwork-A review. Clin Exp Ophthalmol 2022; 50:163-182. [PMID: 35037377 DOI: 10.1111/ceo.14027] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/19/2021] [Accepted: 11/26/2021] [Indexed: 12/11/2022]
Abstract
The trabecular meshwork regulates aqueous humour outflow from the anterior chamber of the eye. It does this by establishing a tunable outflow resistance, defined by the interplay between cells and their extracellular matrix (ECM) milieu, and the molecular interactions between ECM proteins. During normal tissue homeostasis, the ECM is remodelled and trabecular cell behaviour is modified, permitting increased aqueous fluid outflow to maintain intraocular pressure (IOP) within a relatively narrow physiological pressure. Dysfunction in the normal homeostatic process leads to increased outflow resistance and elevated IOP, which is a primary risk factor for glaucoma. This review delineates some of the changes in the ECM that lead to gross as well as some more subtle changes in the structure and function of the ECM, and their impact on trabecular cell behaviour. These changes are discussed in the context of outflow resistance and glaucoma.
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Affiliation(s)
- Kate E Keller
- Casey Eye Institute, Oregon Health &Science University, Portland, Oregon, USA
| | - Donna M Peters
- Department of Pathology & Laboratory Medicine, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, USA
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