Coordinated Regulation of Extracellular Matrix Synthesis by the MicroRNA-29 Family in the Trabecular Meshwork

Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA.
Investigative ophthalmology & visual science (Impact Factor: 3.4). 02/2011; 52(6):3391-7. DOI: 10.1167/iovs.10-6165
Source: PubMed


The microRNA-29 (miR-29) family has emerged, in various tissues, as a key modulator of extracellular matrix (ECM) homeostasis. In this study, the authors investigate the role of the miR-29 family in the regulation of ECM synthesis in the trabecular meshwork (TM) under basal and TGF-β2 stimulatory conditions.
Human TM cells were incubated with 2.5 ng/mL activated, recombinant human TGF-β2 for 24, 48, and 72 hours. A specific pharmacologic inhibitor was used to block SMAD3 function in the context of TGF-β2 stimulation. Changes in the expression of the miR-29 family were assessed by real-time PCR. The effect of miR-29 molecules and inhibitors on ECM levels was determined by immunoblot analysis.
All three members of the miR-29 family were expressed in cultured TM cells. Although the incubation of TM cells with TGF-β2 induced miR-29a and suppressed miR-29b levels, no significant effect was observed on miR-29c expression. Additional studies revealed that SMAD3 modulates miR-29b expression under basal and TGF-β2 conditions. Subsequent gain- and loss-of-function experiments demonstrated that the miR-29 family functions as a critical suppressor of various ECM proteins under basal and TGF-β2 stimulatory conditions.
The findings derived from this study identify the miR-29 family as a critical regulator of ECM expression in the TM and suggest that its modulation by TGF-β2 may be important in controlling ECM synthesis. Together, these data provide further insight into the complex regulatory mechanisms mediating TGF-β2 signaling and ECM production in the TM.

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    • "Critical regulator of ECM expression in the TM, mediating TGF2 signaling Villarreal et al. 2011 [181] miR-29 It could play an important role in modulating TGFs on the outflow pathway Luna et al. 2011 [182] miR-204 and "
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    ABSTRACT: Glaucoma targets a variety of different tissues located in both anterior (e.g., trabecular meshwork) and posterior (e.g., optic nerve head) ocular segments. The transmission of damage between these structures cannot be simply ascribed to intraocular pressure increase. Recent experimental findings provide evidence for the involvement of molecular mediators including proteins and microRNAs. Aqueous humor protein composition is characteristically altered during glaucoma progression. Immunohistochemistry analyses indicate that proteins characterizing glaucomatous aqueous humor are released by damaged trabecular meshwork. This feature incudes (a) Nestin, involved in stem cell recruitment and glial cell activation; (b) A Kinase anchor protein, released as consequence of mitochondrial damage and Rho activation establishing cell shape and motility; (c) Actin related protein 2/3 complex, involved in actin polymerization and cell shape maintenance. As established both in vitro and in glaucomatous aqueous humor, trabecular meshwork cells damaged by oxidative stress release extracellular microRNAs inducing glial cell activation, an established pathogenic mechanism in neurodegenerative diseases. Released microRNAs include miR-21 (apoptosis), miR-450 (cell aging, maintenance of contractile tone), miR-107 (Nestin expression, apoptosis), miR-149 (endothelia and extracellular matrix homeostasis). Experimental evidences indicate that the uveoscleral pathway, via suprachoroidal space, can provide a potential route of access from the anterior region to the posterior segment of the eye and could represent the path followed by biologic mediators to reach the inner layer of the peripapillary retina and transmit damage signals from the anterior to posterior segment during glaucoma course.
    07/2015; 4(1). DOI:10.2174/2211536604666150707124640
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    • "It has been predicted that 30% of human genes may be regulated by miRNAs [8]. Studies have also shown that miRNAs play an important role in the development of the eye, ocular homeostasis, and ocular diseases [9]. A group of miRNAs has also been shown to play critical roles in different pathways in a laser-induced CNVM mouse model [10]. "
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    ABSTRACT: Purpose In the present study, we aimed to investigate the changes in plasma miRNA in patients with wet age-related macular degeneration. Methods The expression profiles of 384 miRNAs in plasma from 33 patients (22 male, 11 female) who were diagnosed with wet age-related macular degeneration with fundus examination, fundus fluorescein angiography, and optical coherence tomography and 31 controls (17 male, 14 female) were evaluated using high-throughput quantitative real-time PCR. Results Our results demonstrated that the expression level of five miRNAs (miR-17-5p, miR-20a-5p, miR-24-3p, miR-106a-5p, and miR-223-3p) was significantly upregulated in patients with age-related macular degeneration when compared to the control group (p<0.05). The expression level of 11 miRNAs (miR-21-5p, miR-25-3p, miR-140-3p, miR-146b-5p, miR-192-5p, miR-335-5p, miR-342-3p, miR-374a-5p, miR-410, miR-574-3p, and miR-660-5p) was significantly downregulated in patients (p<0.05). In addition, ten miRNAs (miR-26b-5p, miR-27b-3p, miR-29a-3p, miR-139-3p, miR-212–3p, miR-324-3p, miR-324-5p, miR-532-3p, miR-744-5p, and miR-Let-7c) were expressed only in the patient group. Conclusions Our results suggest that plasma miRNA levels may change in wet age-related macular degeneration. These molecules may have an important therapeutic target in patients who are unresponsive to antivascular endothelial growth factor therapy. However, further studies must be conducted for possible effects of miRNAs in vascular disorders of eye such as age-related macular degeneration.
    Molecular vision 07/2014; 20:1057-66. · 1.99 Impact Factor
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    • "For example, the above discussed TGF-β2 signaling-dependent miR-29 family members were shown to play a role in the maintenance of the ECM homeostasis. Expression of miR-29 members in human cell culture resulted in significant reduction of the ECM components, such as laminin, fibronectin, collagen I, collagen IV, and SPRC (secreted protein, acidic, and rich in cysteine; Villarreal et al., 2011). miR-133, which is secreted from diseased myocardium following AMI, was shown in the experiments in rats and in human cell culture to directly target 3 UTR of the pro-α1 chains of type I collagen, changing the ECM properties of the recipient tissues (Castoldi et al., 2012). "
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    ABSTRACT: The extracellular environment is a complex entity comprising of the extracellular matrix (ECM) and regulatory molecules. It is highly dynamic and under cell-extrinsic stress, transmits the stressed organism's state to each individual ECM-connected cell. microRNAs (miRNAs) are regulatory molecules involved in virtually all the processes in the cell, especially under stress. In this review, we analyse how miRNA expression is regulated downstream of various signal transduction pathways induced by changes in the extracellular environment. In particular, we focus on the muscular dystrophy-associated cell adhesion molecule dystroglycan capable of signal transduction. Then we show how exactly the same miRNAs feedback to regulate the extracellular environment. The ultimate goal of this bi-directional signal transduction process is to change cell behavior under cell-extrinsic stress in order to respond to it accordingly.
    Frontiers in Genetics 12/2013; 4:305. DOI:10.3389/fgene.2013.00305
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