scholarly journals Cathepsin K Regulates Intraocular Pressure by Modulating Extracellular Matrix Remodeling and Actin-Bundling in the Trabecular Meshwork Outflow Pathway

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2864
Author(s):  
Avinash Soundararajan ◽  
Sachin Anil Ghag ◽  
Sai Supriya Vuda ◽  
Ting Wang ◽  
Padmanabhan Paranji Pattabiraman
Keyword(s):  
Extracellular Matrix ◽  
Intraocular Pressure ◽  
Actin Cytoskeleton ◽  
Trabecular Meshwork ◽  
Critical Role ◽  
Constitutive Expression ◽  
Cathepsin K ◽  
Actin Dynamics ◽  
Actin Depolymerization ◽  
Outflow Pathway

The homeostasis of extracellular matrix (ECM) and actin dynamics in the trabecular meshwork (TM) outflow pathway plays a critical role in intraocular pressure (IOP) regulation. We studied the role of cathepsin K (CTSK), a lysosomal cysteine protease and a potent collagenase, on ECM modulation and actin cytoskeleton rearrangements in the TM outflow pathway and the regulation of IOP. Initially, we found that CTSK was negatively regulated by pathological stressors known to elevate IOP. Further, inactivating CTSK using balicatib, a pharmacological cell-permeable inhibitor of CTSK, resulted in IOP elevation due to increased levels and excessive deposition of ECM-like collagen-1A in the TM outflow pathway. The loss of CTSK activity resulted in actin-bundling via fascin and vinculin reorganization and by inhibiting actin depolymerization via phospho-cofilin. Contrarily, constitutive expression of CTSK decreased ECM and increased actin depolymerization by decreasing phospho-cofilin, negatively regulated the availability of active TGFβ2, and reduced the levels of alpha-smooth muscle actin (αSMA), indicating an antifibrotic action of CTSK. In conclusion, these observations, for the first time, demonstrate the significance of CTSK in IOP regulation by maintaining the ECM homeostasis and actin cytoskeleton-mediated contractile properties of the TM outflow pathway.

Inflammatory Disease and Abortive Platelet Shedding Caused by a Mutation in a Pivotal Regulator of Actin Dynamics in the redears Mouse.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1606-1606
Author(s):  
Monica J. Justice ◽  
Ben T. Kile ◽  
Lanette S. Woodward
Keyword(s):  
Actin Cytoskeleton ◽  
Inflammatory Disease ◽  
Critical Role ◽  
Neutrophil Infiltration ◽  
Blood Platelet ◽  
Forward Genetics ◽  
Actin Dynamics ◽  
Actin Depolymerization ◽  
Function Discovery

Abstract Mouse mutagenesis using forward genetics is valuable as a gene function discovery tool. We are looking for blood defects in a large ENU mutagenesis screen, and have isolated many new mouse mutants that reveal new mechanisms in hematopoiesis. One mutant mouse strain, called redears, is an intriguing model of inflammatory disease and thrombocytopenia. Animals homozygous for the redears (rd) mutation develop spontaneous inflammatory lesions of the ears and tail characterized by neutrophil infiltration and peripheral neutrophila. Unexpectedly, blood platelet numbers are dramatically reduced in rd/rd animals. A thorough analysis of platelet biogenesis shows that the platelet precursor cell, the megakaryocyte, undergoes abnormal maturation, which results in gross morphological abnormalities, increased ploidy and abortive platelet shedding. Here we report a mutation in a novel gene related to the yeast actin-interacting protein Aip1 in rd/rd mice. In yeast, Aip1 interacts with, and increases the activity of cofilin, a key regulator of actin depolymerization. Our data confirm that actin dynamics are dysregulated in rd/rd megakaryocytes and neutrophils. The massive cytoplasmic reorganization that is required for megakaryocyte maturation and platelet shedding has long been assumed to depend on the actin cytoskeleton. Intriguingly, recent studies suggest the process is caspase-dependent, and represents a form of ‘para-apoptosis’. With this in mind, we found that chemotaxis and apoptosis are perturbed in rd/rd neutrophils, suggesting that neutrophils are playing a key role in driving the inflammation. Disrupted actin depolymerization would provide an explanation for chemotactic deficiencies. Further, recent evidence implicating cofilin and other actin regulators in the initiation of apoptosis would suggest that this novel protein may play an essential role in neutrophil cell death. Thus, the redears mouse not only provides the first in vivo demonstration of the critical role of the actin cytoskeleton in megakaryocyte development and platelet production, but also represents a unique reagent to examine the relationship between actin dynamics, cellular maturation, inflammation and apoptosis. Our ongoing mutagenesis efforts continue to reveal new developmental mechanisms. New mutants, genetic tools, and resources can be found at www.mouse-genome.bcm.tmc.edu

scholarly journals SNHG3 cooperates with ELAVL2 to modulate cell apoptosis and extracellular matrix accumulation by stabilizing SNAI2 in human trabecular meshwork cells under oxidative stress

2020 ◽  
Author(s):  
Sizhen Li ◽  
Qingsong Yang ◽  
Zixiu Zhou ◽  
Min Fu ◽  
Xiaodong Yang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Extracellular Matrix ◽  
Intraocular Pressure ◽  
Oxidative Damage ◽  
Trabecular Meshwork ◽  
Cell Apoptosis ◽  
Cell Injury ◽  
Quantitative Polymerase Chain Reaction ◽  
Subcellular Fractionation ◽  
Cell Counting

Abstract Background: Glaucoma is the main reason for irreversible blindness, and pathological increased intraocular pressure is the leading risk factor for glaucoma. It is reported that trabecular meshwork cell injury is closely associated with the elevated intraocular pressure. The current study aimed to investigate the role of SNHG3 in human trabecular meshwork (HTM) cells under oxidative stress. Methods: A series of experiments including real-time quantitative polymerase chain reaction (RT-qPCR), subcellular fractionation assay, western blot analysis, cell counting kit-8 (CCK-8) assay, RNA pull down, flow cytometry analysis, and RIP assay were employed to explore the biological function and regulatory mechanism of SNHG3 in HTM cells under oxidative stress.Results: First, we observed that H2O2 induced SNHG3 upregulation in HTM cells. Then, we found that SNHG3 silencing alleviated H2O2-induced oxidative damage in HTM cells. Moreover, SNAI2 knockdown alleviated the oxidative damage induced by H2O2 in HTM cells. Mechanistically, SNHG3 bound with ELAVL2 to stabilize SNAI2. Finally, SNAI2 overexpression counteracted the effect of SNHG3 silencing on H2O2-induced HTM cells. Conclusion: Our results demonstrated that SNHG3 cooperated with ELAVL2 to modulate cell apoptosis and extracellular matrix (ECM) accumulation by stabilizing SNAI2 in HTM cells under oxidative stress.

scholarly journals Fluctuations in Intraocular Pressure Increase the Trabecular Meshwork Extracellular Matrix

2014 ◽  
Vol 33 (4) ◽  
pp. 1215-1224 ◽  
Author(s):  
Huan Zou ◽  
Rongdi Yuan ◽  
Qijun Zheng ◽  
Yan Huo ◽  
Min Lang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Intraocular Pressure ◽  
Trabecular Meshwork ◽  
Pressure Increase

scholarly journals Overexpression of SPARC in Human Trabecular Meshwork Increases Intraocular Pressure and Alters Extracellular Matrix

2013 ◽  
Vol 54 (5) ◽  
pp. 3309 ◽  
Author(s):  
Dong-Jin Oh ◽  
Min Hyung Kang ◽  
Yen Hoong Ooi ◽  
Kyu Ryong Choi ◽  
E. Helene Sage ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Intraocular Pressure ◽  
Trabecular Meshwork

Abstract 282: Functional Analysis Of Micrornas In Vascular Disease

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Shusheng Wang ◽  
Qinbo Zhou ◽  
Chastain Anderson
Keyword(s):  
Actin Cytoskeleton ◽  
Therapeutic Potential ◽  
Vascular Development ◽  
Critical Role ◽  
Vascular Diseases ◽  
Tube Formation ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Actin Dynamics

microRNAs (miRNA, miR) are emerging as pivotal modulators of vascular development and disease. Research is my lab is focused on elucidating the functional mechanism and exploring therapeutic potential of microRNAs in vascular diseases. Our recent studies have shown that miR-23 and miR-27 in miR-23~27~24 family are required for proper angiogenesis and neovascularization in a laser-induced vascular injury model. Here we extend our study and provide evidence that miR-24 regulates actin dynamics in ECs through targeting multiple members downstream of Rho signaling, including Pak4, Limk2 and Diaph1 proteins. Consistent with the critical role for actin cytoskeleton in cell motility and proliferation, overexpression of miR-24 in ECs blocks stress fiber and lamellipodia formation, represses EC migration, proliferation and tube formation in vitro, as well as angiogenesis in an ex vivo aortic ring assay. Overexpression of miR-24 in transgenic mice represses postnatal retinal vascular development. Moreover, subretinal delivery of miR-24 mimics represses laser-induced CNV in vivo. Mechanistically, knockdown of miR-24 target protein LIMK2 or PAK4 inhibits stress fiber formation and tube formation in vitro, mimicking miR-24 overexpression phenotype in angiogenesis. Taken together, these findings demonstrate that miR-24 represses angiogenesis by simultaneously regulating multiple components in the actin cytoskeleton pathways, suggesting distinct function of miR-23~27~24 family members in angiogenesis. Manipulation of actin cytoskeleton pathways by miR-24 may represent an attractive therapeutic solution for numerous vascular diseases.

scholarly journals Mechanical stretch induces Ca2+ influx and extracellular release of PGE2 through Piezo1 activation in trabecular meshwork cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takatoshi Uchida ◽  
Shota Shimizu ◽  
Reiko Yamagishi ◽  
Suzumi M. Tokuoka ◽  
Yoshihiro Kita ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Intraocular Pressure ◽  
Trabecular Meshwork ◽  
Pressure Fluctuations ◽  
Mechanical Stretch ◽  
Cell Contraction ◽  
Trabecular Meshwork Cells ◽  
Extracellular Release ◽  
Main Pathway ◽  
Outflow Pathway

AbstractThe trabecular meshwork (TM) constitutes the main pathway for aqueous humor drainage and is exposed to complex intraocular pressure fluctuations. The mechanism of homeostasis in which TM senses changes in intraocular pressure and leads to normal levels of outflow resistance is not yet well understood. Previous reports have shown that Piezo1, a mechanically-activated cation channel, is expressed in TM and isolated TM cells. Therefore, we tested hypothesis that Piezo1 may function in response to membrane tension and stretch in TM. In human trabecular meshwork (hTM) cells, PIEZO1 was showed to be abundantly expressed, and Piezo1 agonist Yoda1 and mechanical stretch caused a Piezo1-dependent Ca2+ influx and release of arachidonic acid and PGE2. Treatment with Yoda1 or PGE2 significantly inhibited hTM cell contraction. These results suggest that mechanical stretch stimuli in TM activates Piezo1 and subsequently regulates TM cell contraction by triggering Ca2+ influx and release of arachidonic acid and PGE2. Thus, Piezo1 could acts as a regulator of intraocular pressure (IOP) within the conventional outflow pathway and could be a novel therapeutic strategy to modulate IOP in glaucoma patients.

scholarly journals Molecular taxonomy of human ocular outflow tissues defined by single cell transcriptomics

2020 ◽  
Author(s):  
Gaurang Patel ◽  
Wen Fury ◽  
Hua Yang ◽  
Maria Gomez-Caraballo ◽  
Yu Bai ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Single Cell ◽  
Ocular Hypertension ◽  
Trabecular Meshwork ◽  
Cell Types ◽  
Specific Expression ◽  
Distinct Cell ◽  
Single Cell Rna Sequencing ◽  
Outflow Pathway

ABSTRACTThe conventional outflow pathway is a complex tissue responsible for maintaining intraocular pressure (IOP) homeostasis. The coordinated effort of multiple cells with differing responsibilities ensure healthy outflow function and IOP maintenance. Dysfunction of one or more resident cell type results in ocular hypertension and risk for glaucoma, a leading cause of blindness. In this study, single cell RNA sequencing was performed to generate a comprehensive cell atlas of human conventional outflow tissues. We obtained 17757 genes expression profiles from 8758 cells from eight eyes of four donors representing the outflow cell transcriptome. Upon clustering analysis, 12 distinct cell types were identified, and region-specific expression of candidate genes were mapped in human tissues. Significantly, we identified two distinct expression patterns (myofibroblast and fibroblast) from cells located in the trabecular meshwork (TM), the primary structural component of the conventional outflow pathway. We also located neuron and macrophage signatures in the TM. The second primary component structure, Schlemm’s canal displayed a unique combination of lymphatic/blood vascular gene expression. Other expression clusters corresponded to cells from neighboring tissues, predominantly in the ciliary muscle/scleral spur, which together correspond to the uveoscleral outflow path. Importantly, the utility of our atlas was demonstrated by mapping glaucoma-relevant genes to outflow cell clusters. Our study provides a comprehensive molecular and cellular classification of conventional and unconventional outflow pathway structures responsible for IOP homeostasis.Significance statementOcular hypertension is the primary, and only modifiable risk factor for glaucoma, the leading cause of irreversible blindness. Intraocular pressure is regulated homeostatically by resistance to aqueous humor outflow through an architecturally complex tissue, the conventional/trabecular pathway. In this study, we generated a comprehensive cell atlas of the human trabecular meshwork and neighboring tissues using single cell, RNA sequencing. We identified 12 distinct cell types, and mapped region-specific expression of candidate genes. The utility of our atlas was demonstrated by mapping glaucoma-relevant genes to conventional outflow cell clusters. Our study provides a comprehensive molecular and cellular classification of tissue structures responsible for intraocular pressure homeostasis in health, and dysregulation in disease.

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