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Johnstone M, Xin C, Acott T, Vranka J, Wen J, Martin E, Wang RK. Valve-Like Outflow System Behavior With Motion Slowing in Glaucoma Eyes: Findings Using a Minimally Invasive Glaucoma Surgery–MIGS-Like Platform and Optical Coherence Tomography Imaging. Front Med (Lausanne) 2022; 9:815866. [PMID: 35572956 PMCID: PMC9099151 DOI: 10.3389/fmed.2022.815866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/31/2022] [Indexed: 01/01/2023] Open
Abstract
PurposeThis study aimed to investigate anatomic relationships and biomechanics of pressure-dependent trabecular meshwork and distal valve-like structure deformation in normal and glaucoma eyes using high-resolution optical coherence tomography (HR-OCT).MethodsWe controlled Schlemm’s canal (SC) pressure during imaging with HR-OCT in segments of three normal (NL) and five glaucomatous (GL) ex vivo eyes. The dissected limbal wedges were studied from 15 locations (5 NL and 10 GL). A minimally invasive glaucoma surgery (MIGS)-like cannula was inserted into the SC lumen, whereas the other end was attached to a switch between two reservoirs, one at 0, the other at 30 mm Hg. A steady-state pressure of 30 mm Hg was maintained to dilate SC and collector channels (CC) during 3D volume imaging. The resulting 3D lumen surface relationships were correlated with internal structural features using an image mask that excluded tissues surrounding SC and CC. While imaging with HR-OCT, real-time motion responses in SC and CC areas were captured by switching pressure from 0 to 30 or 30 to 0 mm Hg. NL vs. GL motion differences were compared.ResultsLumen surface and internal relationships were successfully imaged. We identified SC inlet and outlet valve-like structures. In NL and GL, the mean SC areas measured at the steady-state of 0 and 30 mm Hg were each significantly different (p < 0.0001). Synchronous changes in SC and CC lumen areas occurred in <200 ms. Measured SC area differences at the steady-state 0 and 30 mmHg, respectively, were larger in NL than GL eyes (p < 0.0001). The SC motion curves rose significantly more slowly in GL than NL (p < 0.001). Pressure waves traveled from the cannula end along the SC lumen to CC and deep intrascleral channels.ConclusionHR-OCT provided simultaneous measurements of outflow pathway lumen surfaces, internal structures, and biomechanics of real-time pressure-dependent dimension changes. We identified SC inlet and outlet valve-like structures. GL tissues underwent less motion and responded more slowly than NL, consistent with increased tissue stiffness. A MIGS-like shunt to SC permitted pulse waves to travel distally along SC lumen and into CC.
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Affiliation(s)
- Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
- *Correspondence: Murray Johnstone,
| | - Chen Xin
- Department of Ophthalmology, Tongren Hospital, Beijing, China
| | - Ted Acott
- Department of Ophthalmology, Casey Eye Institute, Portland, OR, United States
| | - Janice Vranka
- Department of Ophthalmology, Casey Eye Institute, Portland, OR, United States
| | - Joanne Wen
- Department of Ophthalmology, Duke Eye Center, Durham, NC, United States
| | - Elizabeth Martin
- Department of Ophthalmology, Indiana University, Indianapolis, IN, United States
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
- Department of Bioengineering, University of Washington, Seattle, WA, United States
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Dhamodaran K, Baidouri H, Nartey A, Staverosky J, Keller K, Acott T, Vranka J, Raghunathan V. Endogenous expression of Notch pathway molecules in human trabecular meshwork cells. Exp Eye Res 2022; 216:108935. [PMID: 35033558 PMCID: PMC8885976 DOI: 10.1016/j.exer.2022.108935] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/23/2021] [Accepted: 01/05/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE Cells in the trabecular meshwork sense and respond to a myriad of physical forces through a process known as mechanotransduction. Whilst the effect of substratum stiffness or stretch on TM cells have been investigated in the context of transforming growth factor (TGF-β), Wnt and YAP/TAZ pathways, the role of Notch signaling, an evolutionarily conserved pathway, recently implicated in mechanotransduction, has not been investigated in trabecular meshwork (TM) cells. Here, we compare the endogenous expression of Notch pathway molecules in TM cells from glaucomatous and non-glaucomatous donors, segmental flow regions, and when subjected to cyclical strain, or grown on hydrogels of varying rigidity. METHODS Primary TM from glaucomatous (GTM), non-glaucomatous (NTM) donors, and from segmental flow regions [high flow (HF), low flow (LF)], were utilized between passages 2-6. Cells were (i) plated on tissue culture plastic, (ii) subjected to cyclical strain (6 h and 24 h), or (iii) cultured on 3 kPa and 80 kPa hydrogels. mRNA levels of Notch receptors/ligands/effectors in the TM cells was determined by qRT-PCR. Phagocytosis was determined as a function of substratum stiffness in NTM-HF/LF cells in the presence or absence of 100 nM Dexamethasone treatment. RESULTS Innate expression of Notch pathway genes were significantly overexpressed in GTM cells with no discernible differences observed between HF/LF cells in either NTM or GTM cells cultured on plastic substrates. With 6 h of cyclical strain, a subset of Notch pathway genes presented with altered expression. Expression of Notch receptors/ligands/receptors/inhibitors progressively declined with increasing stiffness and this correlated with phagocytic ability of NTM cells. Dexamethasone treatment decreased phagocytosis regardless of stiffness or cells isolated from segmental outflow regions. CONCLUSIONS We demonstrate here that the Notch expression in cultured TM cells differ intrinsically between GTM vs NTM, and by substratum cues (cyclical strain and stiffness). Of import, the most apparent differences in gene expression were observed as a function of substratum stiffness which closely followed phagocytic ability of cells. Interestingly, on soft substrates (mimicking normal TM stiffness) Notch expression and phagocytosis was highest, while both expression and phagocytosis was significantly lower on stiffer substrates (mimicking glaucomatous stiffness) regardless of DEX treatment. Such context dependent changes suggest Notch pathway may play differing roles in disease vs homeostasis. Studies focused on understanding the mechanistic role of Notch (if any) in outflow homeostasis are thus warranted.
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Affiliation(s)
- Kamesh Dhamodaran
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Hasna Baidouri
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Andrews Nartey
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Julia Staverosky
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Kate Keller
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Ted Acott
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - Janice Vranka
- Casey Eye Institute, Oregon Health and Sciences University, Portland, OR, USA
| | - VijayKrishna Raghunathan
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA,Department of Biomedical Engineering, University of Houston, Houston, TX, USA,Correspondence should be sent to: VijayKrishna Raghunathan, Ph.D., University of Houston, College of Optometry, 4901 Calhoun Rd, Houston, TX, 77204, Phone: (713)-743-8331,
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Yemanyi F, Vranka J, Raghunathan VK. Crosslinked Extracellular Matrix Stiffens Human Trabecular Meshwork Cells Via Dysregulating β-catenin and YAP/TAZ Signaling Pathways. Invest Ophthalmol Vis Sci 2021; 61:41. [PMID: 32832971 PMCID: PMC7452853 DOI: 10.1167/iovs.61.10.41] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose The purpose of this study was to determine whether genipin-induced crosslinked cell-derived matrix (XCDM) precipitates fibrotic phenotypes in human trabecular meshwork (hTM) cells by dysregulating β-catenin and Yes-associated protein (YAP)/ transcriptional coactivator with PDZ-binding motif (TAZ) signaling pathways. Methods Cell-derived matrices were treated with control or genipin for 5 hours to obtain respective uncrosslinked (CDM) and XCDMs and characterized. hTM cells were seeded on these matrices with/without Wnt pathway modulators in serum-free media for 24 hours. Elastic modulus, gene, and protein (whole cell and subcellular fractions) expressions of signaling mediators and targets of Wnt/β-catenin and YAP/TAZ pathways were determined. Results At the highest genipin concentration (10% XCDM), XCDM had increased immunostaining of N-ε(γ-glutamyl)-lysine crosslinks, appeared morphologically fused, and was stiffer (5.3-fold, P < 0.001). On 10% XCDM, hTM cells were 7.8-fold (P < 0.001) stiffer, total β-catenin was unchanged, pβ-catenin was elevated, and pGSK3β was suppressed. Although 10% XCDM had no effect on cytoplasmic β-catenin levels, it reduced nuclear β-catenin, cadherin 11, and key Wnt target genes/proteins. The 10% XCDM increased total TAZ, decreased pTAZ, and increased cytoplasmic TAZ levels in hTM cells. The 10% XCDM increased total YAP, reduced nuclear YAP levels, and critical YAP/TAZ target genes/proteins. Wnt activation rescued hTM cells from 10% XCDM-induced stiffening associated with increased nuclear β-catenin. Conclusions Increased cytoplasmic TAZ may inhibit β-catenin from its nuclear shuttling or regulating cadherin 11 important for aqueous homeostasis. Elevated cytoplasmic TAZ may inhibit YAP's probable homeostatic function in the nucleus. Together, TAZ's cytoplasmic localization may be an important downstream event of how increased TM extracellular matrix (ECM) crosslinking may cause increased stiffness and ocular hypertension in vivo. However, Wnt pathway activation may ameliorate ocular hypertensive phenotypes induced by crosslinked ECM.
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Affiliation(s)
- Felix Yemanyi
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, United States
| | - Janice Vranka
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, United States
| | - Vijay Krishna Raghunathan
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, United States.,Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, United States
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Yemanyi F, Vranka J, Raghunathan VK. Glucocorticoid-induced cell-derived matrix modulates transforming growth factor β2 signaling in human trabecular meshwork cells. Sci Rep 2020; 10:15641. [PMID: 32973273 PMCID: PMC7518434 DOI: 10.1038/s41598-020-72779-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 07/28/2020] [Indexed: 01/11/2023] Open
Abstract
Aberrant remodeling of trabecular meshwork (TM) extracellular matrix (ECM) may induce ocular hypertensive phenotypes in human TM (hTM) cells to cause ocular hypertension, via a yet unknown mechanism. Here, we show that, in the absence of exogenous transforming growth factor-beta2 (TGFβ2), compared with control matrices (VehMs), glucocorticoid-induced cell-derived matrices (GIMs) trigger non-Smad TGFβ2 signaling in hTM cells, correlated with overexpression/activity of structural ECM genes (fibronectin, collagen IV, collagen VI, myocilin), matricellular genes (connective tissue growth factor [CTGF], secreted protein, acidic and rich in cysteine), crosslinking genes/enzymes (lysyl oxidase, lysyl oxidase-like 2–4, tissue transglutaminase-2), and ECM turnover genes/enzymes (matrix metalloproteinases-MMP2,14 and their inhibitors-TIMP2). However, in the presence of exogenous TGFβ2, VehMs and GIMs activate Smad and non-Smad TGFβ2 signaling in hTM cells, associated with overexpression of α-smooth muscle actin (α-SMA), and differential upregulation of aforementioned ECM genes/proteins with new ones emerging (collagen-I, thrombospondin-I, plasminogen activator inhibitor, MMP1, 9, ADAMTS4, TIMP1); with GIM-TGFβ2-induced changes being mostly more pronounced. This suggests dual glaucomatous insults potentiate profibrotic signaling/phenotypes. Lastly, we demonstrate type I TGFβ receptor kinase inhibition abrogates VehM-/GIM- and/or TGFβ2-induced upregulation of α-SMA and CTGF. Collectively, pathological TM microenvironments are sufficient to elicit adverse cellular responses that may be ameliorated by targeting TGFβ2 pathway.
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Affiliation(s)
- Felix Yemanyi
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA
| | - Janice Vranka
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - Vijay Krishna Raghunathan
- Department of Basic Sciences, College of Optometry, University of Houston, Houston, TX, USA. .,Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, USA.
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Abstract
Ocular hypertension has been attributed to increased resistance to aqueous outflow often as a result of changes in trabecular meshwork (TM) extracellular matrix (ECM) using in vivo animal models (for example, by genetic manipulation) and ex vivo anterior segment perfusion organ cultures. These are, however, complex and difficult in dissecting molecular mechanisms and interactions. In vitro approaches to mimic the underlying substrate exist by manipulating either ECM topography, mechanics, or chemistry. These models best investigate the role of individual ECM protein(s) and/or substrate property, and thus do not recapitulate the multifactorial extracellular microenvironment; hence, mitigating its physiological relevance for mechanistic studies. Cell-derived matrices (CDMs), however, are capable of presenting a 3D-microenvironment rich in topography, chemistry, and whose mechanics can be tuned to better represent the network of native ECM constituents in vivo. Critically, the composition of CDMs may also be fine-tuned by addition of small molecules or relevant bioactive factors to mimic homeostasis or pathology. Here, we first provide a streamlined protocol for generating CDMs from TM cell cultures from normal or glaucomatous donor tissues. Second, we document how TM cells can be pharmacologically manipulated to obtain glucocorticoid-induced CDMs and how generated pristine CDMs can be manipulated with reagents like genipin. Finally, we summarize how CDMs may be used in mechanistic studies and discuss their probable application in future TM regenerative studies.
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Affiliation(s)
- Felix Yemanyi
- Department of Basic Sciences, University of Houston, Houston, TX, United States
| | - Janice Vranka
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, United States
| | - VijayKrishna Raghunathan
- Department of Basic Sciences, University of Houston, Houston, TX, United States; The Ocular Surface Institute, College of Optometry, University of Houston, Houston, TX, United States; Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX, United States.
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Raghunathan VK, Benoit J, Kasetti R, Zode G, Salemi M, Phinney BS, Keller KE, Staverosky JA, Murphy CJ, Acott T, Vranka J. Glaucomatous cell derived matrices differentially modulate non-glaucomatous trabecular meshwork cellular behavior. Acta Biomater 2018. [PMID: 29524673 DOI: 10.1016/j.actbio.2018.02.037] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ocular hypertension is a causal risk-factor to developing glaucoma. This is associated with stiffening of the trabecular meshwork (TM), the primary site of resistance to aqueous-humor-outflow. The mechanisms underlying this stiffening or how pathologic extracellular matrix (ECM) affects cell function are poorly understood. It is recognized that mechanotransduction systems allow cells to sense and translate the intrinsic biophysical properties of ECM into intracellular signals to control gene transcription, protein expression, and cell behavior. Using an anterior segment perfusion model, we document that there are significantly more low flow regions that are much stiffer, and fewer high flow regions that are less stiff in glaucomatous TM (GTM) when compared to non-glaucomatous TMs (NTM). GTM tissue also has fewer cells overall when compared with NTM tissue. In order to study the role of pathologic ECM in glaucoma disease progression, we conducted studies using cell derived matrices (CDM). First, we characterized the mechanics, composition and organization of fibronectin in ECM deposited by GTM and NTM cells treated with glucocorticosteroids. Then, we determined that these GTM-derived ECM are able to induce stiffening of normal NTM cells, and alter their gene/protein expression to resemble that of a glaucomatous phenotype. Further, we demonstrate that GTM-derived ECM causes endoplasmic reticular stress in NTM. They also became resistant to being reorganized by these NTM cells. These phenomena were exacerbated by ECMs obtained from steroid treated glaucoma model groups. Collectively, our data demonstrates that CDMs represent a novel tool for the study of bidirectional interactions between TM cells and their immediate microenvironment. STATEMENT OF SIGNIFICANCE Extracellular matrix (ECM) changes are prevalent in a number of diseases. The precise mechanisms by which changes in the ECM contribute to disease progression is unclear, primarily due to absence of appropriate models. Here, using glaucoma as a disease model, we document changes in cell derived matrix (CDM) and tissue mechanics that contribute to the pathology. Subsequently, we determine the effect that ECMs from diseased and healthy individuals have on healthy cell behaviors. Data emanating from this study demonstrate that CDMs are a potent tool for the study of cell-ECM interactions.
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Abstract
Collagen requires hydroxylation of its proline residues to achieve proper assembly, structure, and function. Prolyl 4-hydroxylase catalyzes formation of 4-hydroxyproline, which is essential for collagen triple helix formation and stability. Prolyl 3-hydroxylase catalyzes formation of 3-hydroxyproline, which is far less abundant in collagens and whose function remains unclear. Recently mutations in prolyl 3-hydroxylase 1 have been associated with osteogenesis imperfecta, yet the temporal and spatial expression patterns of the prolyl 3-hydroxylase family members during development and in adult tissues remain undefined. By northern blot analysis distinct differences in transcript sizes of the three prolyl 3-hydroxylase genes were detected. Quantitative RTPCR demonstrated tissue-specific differences in prolyl 3-hydroxylase expression, most notable of which were high levels of prolyl 3-hydroxylase 2 in kidney and prolyl 3-hydroxylase 1 expression in embryonic tissues. Finally, in situ hybridization was used to assess spatio-temporal distribution of three prolyl 3-hydroxylases at embryonic days 11-15. Importantly, prolyl 3-hydroxylase 1 was expressed within cartilage condensations of the vertebral bodies and in the aortic arch of the developing heart, whereas prolyl 3-hydroxylase 2 was expressed in developing lens capsule. The prolyl 3-hydroxylase 3 gene showed more generalized expression overlapping somewhat with the other two genes. This report characterizes expression of the three prolyl 3-hydroxylase genes in embryonic and adult mice. Overall these data demonstrate tissue specific prolyl 3-hydroxylase gene expression in both fetal and adult tissues indicating a developmental role for prolyl 3-hydroxylase activity.
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Affiliation(s)
- Janice Vranka
- Research Department, Shriners Hospital for Children, Portland, Oregon 97239, USA
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Ishikawa Y, Vranka J, Wirz J, Nagata K, Bächinger HP. The Rough Endoplasmic Reticulum-resident FK506-binding Protein FKBP65 Is a Molecular Chaperone That Interacts with Collagens. J Biol Chem 2008; 283:31584-90. [DOI: 10.1074/jbc.m802535200] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Morello R, Bertin TK, Chen Y, Hicks J, Tonachini L, Monticone M, Castagnola P, Rauch F, Glorieux FH, Vranka J, Bächinger HP, Pace JM, Schwarze U, Byers PH, Weis M, Fernandes RJ, Eyre DR, Yao Z, Boyce BF, Lee B. CRTAP Is Required for Prolyl 3- Hydroxylation and Mutations Cause Recessive Osteogenesis Imperfecta. Cell 2006; 127:291-304. [PMID: 17055431 DOI: 10.1016/j.cell.2006.08.039] [Citation(s) in RCA: 401] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 05/04/2006] [Accepted: 08/18/2006] [Indexed: 11/26/2022]
Abstract
Prolyl hydroxylation is a critical posttranslational modification that affects structure, function, and turnover of target proteins. Prolyl 3-hydroxylation occurs at only one position in the triple-helical domain of fibrillar collagen chains, and its biological significance is unknown. CRTAP shares homology with a family of putative prolyl 3-hydroxylases (P3Hs), but it does not contain their common dioxygenase domain. Loss of Crtap in mice causes an osteochondrodysplasia characterized by severe osteoporosis and decreased osteoid production. CRTAP can form a complex with P3H1 and cyclophilin B (CYPB), and Crtap-/- bone and cartilage collagens show decreased prolyl 3-hydroxylation. Moreover, mutant collagen shows evidence of overmodification, and collagen fibrils in mutant skin have increased diameter consistent with altered fibrillogenesis. In humans, CRTAP mutations are associated with the clinical spectrum of recessive osteogenesis imperfecta, including the type II and VII forms. Hence, dysregulation of prolyl 3-hydroxylation is a mechanism for connective tissue disease.
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Affiliation(s)
- Roy Morello
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Vranka J, Mokashi A, Keene DR, Tufa S, Corson G, Sussman M, Horton WA, Maddox K, Sakai L, Bächinger HP. Selective intracellular retention of extracellular matrix proteins and chaperones associated with pseudoachondroplasia. Matrix Biol 2001; 20:439-50. [PMID: 11691584 DOI: 10.1016/s0945-053x(01)00148-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Mutations in the cartilage oligomeric matrix protein (COMP) gene result in pseudoachondroplasia (PSACH), which is a chondrodysplasia characterized by early-onset osteoarthritis and short stature. COMP is a secreted pentameric glycoprotein that belongs to the thrombospondin family of proteins. We have identified a novel missense mutation which substitutes a glycine for an aspartic acid residue in the thrombospondin (TSP) type 3 calcium-binding domain of COMP in a patient diagnosed with PSACH. Immunohistochemistry and immunoelectron microscopy both show abnormal retention of COMP within characteristically enlarged rER inclusions of PSACH chondrocytes, as well as retention of fibromodulin, decorin and types IX, XI and XII collagen. Aggrecan and types II and VI collagen were not retained intracellularly within the same cells. In addition to selective extracellular matrix components, the chaperones HSP47, protein disulfide isomerase (PDI) and calnexin were localized at elevated levels within the rER vesicles of PSACH chondrocytes, suggesting that they may play a role in the cellular retention of mutant COMP molecules. Whether the aberrant rER inclusions in PSACH chondrocytes are a direct consequence of chaperone-mediated retention of mutant COMP or are otherwise due to selective intracellular protein interactions, which may in turn lead to aggregation within the rER, is unclear. However, our data demonstrate that retention of mutant COMP molecules results in the selective retention of ECM molecules and molecular chaperones, indicating the existence of distinct secretory pathways or ER-sorting mechanisms for matrix molecules, a process mediated by their association with various molecular chaperones.
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Affiliation(s)
- J Vranka
- Research Department, Shriners Hospital for Children, Portland, OR 97201, USA
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Bradley JM, Vranka J, Colvis CM, Conger DM, Alexander JP, Fisk AS, Samples JR, Acott TS. Effect of matrix metalloproteinases activity on outflow in perfused human organ culture. Invest Ophthalmol Vis Sci 1998; 39:2649-58. [PMID: 9856774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
PURPOSE To test the hypothesis that extracellular matrix turnover, mediated by the matrix metalloproteinases, modulates aqueous humor outflow facility in a human outflow model. METHODS Matrix metalloproteinase activity was manipulated and outflow facility evaluated using perfused human anterior segment organ culture. Purified matrix metalloproteinases, tissue inhibitors of metalloproteinases (TIMPs), and several families of synthetic inhibitors of matrix metalloproteinases were added to the perfusion medium. Matrix metalloproteinase expression was increased by adding recombinant interleukin (IL)-1alpha. Kinetic inhibition analysis was conducted for stromelysin, gelatinase A, and gelatinase B with the various inhibitors. Live-dead staining was used to evaluate culture viability. RESULTS Increasing metalloproteinase activity, by adding purified metalloproteinases or by inducing their expression by IL-1alpha treatment, increased outflow facility. Inhibition of endogenous trabecular metalloproteinase activity using TIMP or several families of synthetic metalloproteinase inhibitors reduced outflow rates. The elevation and the reduction of outflow rates were reversible, with changes requiring 1 to 3 days. Kinetic enzyme inhibition analysis produced 50% inhibitory concentration values for these inhibitors that were compatible with the concentration ranges for outflow inhibition. CONCLUSIONS. The ability of several specific matrix metalloproteinase inhibitors to reduce outflow facility implies that endogenous extracellular matrix turnover by these enzymes was required for the maintenance of trabecular outflow resistance, at least in this human culture model. These observations provide support for the hypothesis that controlled extracellular matrix turnover is important in the regulation of aqueous humor outflow facility.
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Affiliation(s)
- J M Bradley
- Department of Ophthalmology, Casey Eye Institute, Oregon Health Sciences University, Portland 97201, USA
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Krahulec I, Ambrusová L, Dresslerová Y, Rafajdusová I, Vranka J. [Incidence of voice and speech disorders in children from selected kindergartens in Bratislava]. Cesk Otolaryngol 1985; 34:48-54. [PMID: 3967324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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