MiR-22-3p inhibits fibrotic cataract through inactivation of HDAC6 and increase of α-tubulin acetylation

Pericardial Fluid Accumulates microRNAs That Regulate Heart Fibrosis after Myocardial Infarction

Pericardial fluid (PF) has been suggested as a reservoir of molecular targets that can be modulated for efficient repair after myocardial infarction (MI). Here, we set out to address the content of this biofluid after MI, namely in terms of microRNAs (miRs) that are important modulators of the cardiac pathological response. PF was collected during coronary artery bypass grafting (CABG) from two MI cohorts, patients with non-ST-segment elevation MI (NSTEMI) and patients with ST-segment elevation MI (STEMI), and a control group composed of patients with stable angina and without previous history of MI. The PF miR content was analyzed by small RNA sequencing, and its biological effect was assessed on human cardiac fibroblasts. PF accumulates fibrotic and inflammatory molecules in STEMI patients, namely causing the soluble suppression of tumorigenicity 2 (ST-2), which inversely correlates with the left ventricle ejection fraction. Although the PF of the three patient groups induce similar levels of fibroblast-to-myofibroblast activation in vitro, RNA sequencing revealed that PF from STEMI patients is particularly enriched not only in pro-fibrotic miRs but also anti-fibrotic miRs. Among those, miR-22-3p was herein found to inhibit TGF-β-induced human cardiac fibroblast activation in vitro. PF constitutes an attractive source for screening diagnostic/prognostic miRs and for unveiling novel therapeutic targets in cardiac fibrosis.

Consilience and unity in ocular anterior segment research

In his beautiful book, Consilience: The Unity of Knowledge, the eminent biologist Edward O Wilson, advocates the need for integration and reconciliation across the sciences. He defines consilience as "literally a 'jumping together' of knowledge with a linking of facts ... to create a common groundwork of explanation". It is the premise of this paper that as much as basic biomedical research is in need of data generation using the latest available techniques- unifying available knowledge is just as critical. This involves the necessity to resolve contradictory findings, reduce silos, and acknowledge complexity. We take the cornea and the lens as case studies of our premise. Specifically, in this perspective, we discuss the conflicting and fragmented information on protein aggregation, oxidative damage, and fibrosis. These are fields of study that are integrally tied to anterior segment research. Our goal is to highlight the vital need for Wilson's consilience and unity of knowledge which in turn should lead to enhanced rigor and reproducibility, and most importantly, to greater understanding and not simply knowing.

MicroRNA-1225-5p Promotes the Development of Fibrotic Cataracts via Keap1/Nrf2 Signaling

PURPOSE

Fibrotic cataracts, including anterior subcapsular cataract (ASC) as well as posterior capsule opacification (PCO), are a common vision-threatening cause worldwide. Still, little is known about the underlying mechanisms. Here, we demonstrate a miRNA-based pathway regulating the pathological fibrosis process of lens epithelium.

METHODS

Gain- and loss-of-function approaches, as well as multiple fibrosis models of the lens, were applied to validate the crucial role of two miR-1225 family members in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice.

RESULTS

Both miR-1225-3p and miR-1225-5p prominently stimulate the migration and EMT process of lens epithelial cells (LECs) in vitro as well as lens fibrosis in vivo. Moreover, we demonstrated that the underlying mechanism for these effects of miR-1225-5p is via directly targeting Keap1 to regulate Keap1/Nrf2 signaling. In addition, evidence showed that Keap1/Nrf2 signaling is activated in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice, and inhibition of the Nrf2 pathway can significantly reverse the process of LECs EMT as well as lens fibrosis.

CONCLUSIONS

These results suggest that blockade of miR-1225-5p prevents lens fibrosis via targeting Keap1 thereby inhibiting Nrf2 activation. The 'miR-1225-Keap1-Nrf2' signaling axis presumably holds therapeutic promise in the treatment of fibrotic cataracts.

Inhibition of miR-29a-3p Alleviates Apoptosis of Lens Epithelial Cells via Upregulation of CAND1

PURPOSE

Accumulated evidence has shown that microRNAs (miRNAs) are closely related to the pathogenesis and progression of senile cataracts. Here we investigate the effect of miR-29a-3p in cataractogenesis and determined the potential molecular mechanism involved.

METHODS

In this study, we constructed a selenite cataract model in rats and obtained the miRNAs related to cataracts by whole transcriptome sequencing. To investigate the effect and mechanism of miR-29a-3p on cataracts, we performed several in vivo and in vitro experiments, including CCK8 assay, flow cytometry, luciferase reporter assay, Edu assay, and western blot analysis.

RESULT

Sequencing data showed downregulation of miR-29a-3p in rats with selenite cataracts. Down-regulation of miR-29a-3p could promote lens epithelial cells (SRA01/04) proliferation and inhibit cell apoptosis, and miR-29a-3p silence could inhibit the development of cataracts. Additionally, CAND1 was a direct target gene for miR-29a-3p.

CONCLUSION

These data demonstrate that miR-29a-3p inhibits apoptosis of lens epithelial cells by regulating CAND1, which may be a potential target for senile cataracts.

RASFF1A inhibits the epithelial-mesenchymal transition of lens epithelial cells induced by TGFβ through regulating HDAC6

To explore the role of Ras-association domain family 1 A (RASSF1A) in TGFβ2-induced changes of lens epithelial cells (LECs) behavior. The human LEC line SRA01/04 cells were treated with TGFβ2 in the presence or absence of RASSF1A and histone deacetylase 6 (HDAC6). qRT-PCR and western blot were performed to analysis mRNA and proteins expression. Cell proliferation was evaluated using MTT assay and colony formation assay. Transwell and scratch-wound healing assays were conducted to detected cell migration ability. RASSF1A was downregulated in TGFβ2-induced SRA01/04 cells. RASSF1A overexpression inhibited the cell viability, colony formation and migration abilities of SRA01/04 cells induced by TGFβ2. Overexpression of RASSF1A suppressed TGFβ2-induced EMT of SRA01/04 cells, which was manifested as inhibition of EMT-related proteins α-SMA, Vimentin, Snail and Fn expression. Moreover, RASSF1A down-regulated the expression of HDAC6. Importantly, HDAC6 reversed the effects of RASSF1A on SRA01/04 cells. These findings indicate that RASSF1A prevented TGFβ2-induced proliferation, migration, and EMT of LECs by regulating HDAC6 expression, suggesting that RASSF1A holds promise as a potential target for cataracts treatment.

miR-196b-5p regulates inflammatory process and migration via targeting Nras in trabecular meshwork cells

Glaucoma, an insidious ophthalmic pathology, is typified by an aberrant surge in intraocular pressure (IOP) which culminates in the degeneration of retinal ganglion cells and optical neuropathy. The mitigation of IOP stands as the principal therapeutic strategy to forestall vision loss. The trabecular meshwork's (TM) integrity and functionality are pivotal in modulating aqueous humor egress. Despite their potential significance in glaucomatous pathophysiology, the implications of microRNAs (miRNAs) on TM functionality remain largely enigmatic. Transcriptomic sequencing was employed to delineate the miRNA expression paradigm within the limbal region of rodent glaucoma models, aiming to elucidate miRNA-mediated mechanisms within the glaucomatous milieu. Analytical scrutiny of the sequencing data disclosed 174 miRNAs with altered expression profiles, partitioned into 86 miRNAs with augmented expression and 88 with diminished expression. Notably, miRNAs such as hsa-miR-196b-5p were identified as having substantial expression discrepancies with concomitant statistical robustness, suggesting a potential contributory role in glaucomatous progression. Subsequent in vitro assays affirmed that miR-196b-5p augments the inflammatory cascade within immortalized human TM (iHTM) and glaucoma-induced human TM (GTM3) cells, concurrently attenuating cellular proliferation, motility, and cytoskeletal architecture. Additionally, miR-196b-5p implicates itself in the regulation of IOP and inflammatory processes in rodent models. At a mechanistic level, miR-196b-5p modulates its effects via the targeted repression of Nras (neuroblastoma RAS viral oncogene homolog). Collectively, these transcriptomic investigations furnish a comprehensive vista into the regulatory roles of miRNAs within the glaucomatous framework, and the identification of differentially expressed miRNAs alongside their targets could potentially illuminate novel molecular pathways implicated in glaucoma, thereby aiding in the development of innovative therapeutic avenues.

miR-143 promotes cell proliferation, invasion and migration via directly binding to BRD2 in lens epithelial cells

OBJECTIVE

Cataract causes the greatest number of blindnesses worldwide. This study aims to investigate the role of miR-143 in lens epithelial cells.

METHODS

Clustering analysis was conducted to systematically compare miRNA expression levels across cataract and myopia. The levels of miR-143 and Bromodomain containing 2 (BRD2) were determined using real-time quantitative PCR (RT-qPCR) assay in lens epithelial cells. Transwell and wound healing assays were conducted to detect cell invasive and migratory abilities. The regulation relationship between MiR-143 and BRD2 was assessed using dual-luciferase reporter gene assays. BRD2 was knocked down using siRNA-BRD2, and siRNA-BRD2, and miR-143 inhibitors were transfected into cells with lipofectamine 2000.

RESULTS

Through retrieving five databases, 2690 miRNAs were selected. Volcano plot results demonstrated that 200 miRNAs were differentially expressed between cataract and myopia, in which 152 miRNAs were upregulated and 48 miRNAs downregulated in myopia compared with cataract. MiR-143 was upregulated in cataract compared with myopia (P<0.05). MiR-143 inhibitor suppressed the proliferation, invasion and migration of lens epithelial cells (all P<0.05). Luciferase reporter assays confirmed that BRD2 was a miR-143 target gene in SRA01/04 cells. Knockdown of BRD2 promoted SRA01/04 cell proliferation, invasion and migration (all P<0.05). In addition, silencing of BRD2 partially reversed the functions of miR-143 inhibitor on proliferation, invasion and migration (all P<0.05).

CONCLUSION

MiR-143 suppresses lens epithelial cell proliferation, invasion and migration by regulating BRD2, which may support a novel therapeutic strategy for cataract patients.

A framework for Frizzled-G protein coupling and implications to the PCP signaling pathways

The ten Frizzled receptors (FZDs) are essential in Wnt signaling and play important roles in embryonic development and tumorigenesis. Among these, FZD6 is closely associated with lens development. Understanding FZD activation mechanism is key to unlock these emerging targets. Here we present the cryo-EM structures of FZD6 and FZD3 which are known to relay non-canonical planar cell polarity (PCP) signaling pathways as well as FZD1 in their G protein-coupled states and in the apo inactive states, respectively. Comparison of the three inactive/active pairs unveiled a shared activation framework among all ten FZDs. Mutagenesis along with imaging and functional analysis on the human lens epithelial tissues suggested potential crosstalk between the G-protein coupling of FZD6 and the PCP signaling pathways. Together, this study provides an integrated understanding of FZD structure and function, and lays the foundation for developing therapeutic modulators to activate or inhibit FZD signaling for a range of disorders including cancers and cataracts.

Engineering Extracellular Matrix-Bound Nanovesicles Secreted by Three-Dimensional Human Mesenchymal Stem Cells

Extracellular matrix (ECM) in the human tissue contains vesicles, which are defined as matrix-bound nanovesicles (MBVs). MBVs serve as one of the functional components in ECM, recapitulating part of the regulatory roles and in vivo microenvironment. In this study, extracellular vesicles from culture supernatants (SuEVs) and MBVs are isolated from the conditioned medium or ECM, respectively, of 3D human mesenchymal stem cells. Nanoparticle tracking analysis shows that MBVs are smaller than SuEVs (100-150 nm). Transmission electron microscopy captures the typical cup shape morphology for both SuEVs and MBVs. Western blot reveals that MBVs have low detection of some SuEV markers such as syntenin-1. miRNA analysis of MBVs shows that 3D microenvironment enhances the expression of miRNAs such as miR-19a and miR-21. In vitro functional analysis shows that MBVs can facilitate human pluripotent stem cell-derived forebrain organoid recovery after starvation and promote high passage fibroblast proliferation. In macrophage polarization, 2D MBVs tend to suppress the pro-inflammatory cytokine IL-12β, while 3D MBVs tend to enhance the anti-inflammatory cytokine IL-10. This study has the significance in advancing the understanding of the bio-interface of nanovesicles with human tissue and the design of cell-free therapy for treating neurological disorders such as ischemic stroke.

Roles of Histone Acetyltransferases and Deacetylases in the Retinal Development and Diseases

The critical role of epigenetic modification of histones in maintaining the normal function of the nervous system has attracted increasing attention. Among these modifications, the level of histone acetylation, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is essential in regulating gene expression. In recent years, the research progress on the function of HDACs in retinal development and disease has advanced remarkably, while that regarding HATs remains to be investigated. Here, we overview the roles of HATs and HDACs in regulating the development of diverse retinal cells, including retinal progenitor cells, photoreceptor cells, bipolar cells, ganglion cells, and Müller glial cells. The effects of HATs and HDACs on the progression of various retinal diseases are also discussed with the highlight of the proof-of-concept research regarding the application of available HDAC inhibitors in treating retinal diseases.

The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens

The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.

Histone acetyltransferase inhibition reverses opacity in rat galactose-induced cataract

Cataract, a disease that causes opacity of the lens, is the leading cause of blindness worldwide. Cataracts secondary to diabetes are common, even in young patients, so they are of significant clinical importance. Here, we used an ex vivo model of galactose-induced cataracts in the rat lens to investigate the therapeutic effects of histone acetyltransferase (HAT) inhibitors. Among the tested HAT inhibitors, TH1834 was the only one that could reverse most of the opacity once it had formed in the lens. Combination treatment with C646/CPTH2 and CBP30/CPTH2 also had therapeutic effects. In lens cross-sections, vacuoles were present in the tissue of the cortical equatorial region of untreated cataract samples. In treated cataract samples, lens tissue regenerated to fill the vacuoles. To identify the genes regulated by HAT inhibitors, qRT-PCR was performed on treated and untreated cataract samples to determine candidate genes. Expression of Acta1 and Stmn4, both of which are involved in the cytoskeleton, were altered significantly in C646+CPTH2 samples. Expression of Emd, a nuclear membrane protein, and Prtfdc1, which is involved in cancer cell proliferation, were altered significantly in CBP30+CPTH2 samples. Acta1, Acta2, Arrdc3, Hebp2, Hist2h2ab, Pmf1, Ppdpf, Rbm3, RGD1561694, Slc16a6, Slfn13, Tagln, Tgfb1i1, and Tuba1c in TH1834 samples were significantly altered. These genes were primarily related to regulation of cell proliferation, the cytoskeleton, and cell differentiation. Expression levels increased with the onset of cataracts and was suppressed in samples treated with HAT inhibitors.

Noncoding RNAs in cataract formation: star molecules emerge in an endless stream

For decades, research on the pathological mechanism of cataracts has usually focused on the abnormal protein changes caused by a series of risk factors. However, an entire class of molecules, termed non-coding RNA (ncRNA), was discovered in recent years and proven to be heavily involved in cataract formation. Recent studies have recognized the key regulatory roles of ncRNAs in cataracts by shaping cellular activities such as proliferation, apoptosis, migration and epithelial-mesenchymal transition (EMT). This review summarizes our current insight into the biogenesis, properties and functions of ncRNAs and then discusses the development of research on ncRNAs in cataracts. Considering the significant role of ncRNA in cataract formation, research on novel associated regulatory mechanisms is urgently needed, and the development of therapeutic alternatives for the treatment of cataracts seems promising.

Long Non-Coding RNA H19 Prevents Lens Fibrosis through Maintaining Lens Epithelial Cell Phenotypes

The integrity of lens epithelial cells (LECs) lays the foundation for lens function and transparency. By contrast, epithelial-mesenchymal transition (EMT) of LECs leads to lens fibrosis, such as anterior subcapsular cataracts (ASC) and fibrotic forms of posterior capsule opacification (PCO). However, the underlying mechanisms remain unclear. Here, we aimed to explore the role of long non-coding RNA (lncRNA) H19 in regulating TGF-β2-induced EMT during lens fibrosis, revealing a novel lncRNA-based regulatory mechanism. In this work, we identified that lncRNA H19 was highly expressed in LECs, but downregulated by exposure to TGF-β2. In both human lens epithelial explants and SRA01/04 cells, knockdown of H19 aggravated TGF-β2-induced EMT, while overexpressing H19 partially reversed EMT and restored lens epithelial phenotypes. Semi-in vivo whole lens culture and H19 knockout mice demonstrated the indispensable role of H19 in sustaining lens clarity through maintaining LEC features. Bioinformatic analyses further implied a potential H19-centered regulatory mechanism via Smad-dependent pathways, confirmed by in vitro experiments. In conclusion, we uncovered a novel role of H19 in inhibiting TGF-β2-induced EMT of the lens by suppressing Smad-dependent signaling, providing potential therapeutic targets for treating lens fibrosis.

MiR-22-3p Inhibits Proliferation and Promotes Differentiation of Skeletal Muscle Cells by Targeting IGFBP3 in Hu Sheep

The growth and development of skeletal muscle require a series of regulatory factors. MiRNA is a non-coding RNA with a length of about 22 nt, which can inhibit the expression of mRNA and plays an important role in the growth and development of muscle cells. The role of miR-22-3p in C2C12 cells and porcine skeletal muscle has been reported, but it has not been verified in Hu sheep skeletal muscle. Through qPCR, CCK-8, EdU and cell cycle studies, we found that overexpression of miR-22-3p inhibited proliferation of skeletal muscle cells (p < 0.01). The results of qPCR and immunofluorescence showed that overexpression of miR-22-3p promoted differentiation of skeletal muscle cells (p < 0.01), while the results of inhibiting the expression of miR-22-3p were the opposite. These results suggested that miR-22-3p functions in growth and development of sheep skeletal muscle cells. Bioinformatic analysis with mirDIP, miRTargets, and RNAhybrid software suggested IGFBP3 was the target of miR-22-3p, which was confirmed by dual-luciferase reporter system assay. IGFBP3 is highly expressed in sheep skeletal muscle cells. Overexpression of IGFBP3 was found to promote proliferation of skeletal muscle cells indicated by qPCR, CCK-8, EdU, and cell cycle studies (p < 0.01). The results of qPCR and immunofluorescence experiments proved that overexpression of IGFBP3 inhibited differentiation of skeletal muscle cells (p < 0.01), while the results of interfering IGFBP3 with siRNA were the opposite. These results indicate that miR-22-3p is involved in proliferation and differentiation of skeletal muscle cells by targeting IGFBP3.

Circular RNA erythrocyte membrane protein band 4.1 assuages ultraviolet irradiation-induced apoptosis of lens epithelial cells by stimulating 5'-bisphosphate nucleotidase 1 in a miR-24-3p-dependent manner

Apoptosis of lens epithelial cells contributed to the formation of age-related cataract (ARC), and previous data revealed that circular RNA (circRNA) was responsible for the underneath mechanism. The study was organized to explore the role of circular RNA erythrocyte membrane protein band 4.1 (circ_EPB41) in ultraviolet (UV) irradiation-induced apoptosis of lens epithelial cells. SRA01/04 cells were irradiated with UV to mimic the ARC cell model. The RNA levels of circ_EPB41, microRNA-24-3p (miR-24-3p), and 3ʹ(2ʹ), 5ʹ-bisphosphate nucleotidase 1 (BPNT1) were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. 5-Ethynyl-29-deoxyuridine, 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide and DNA content quantitation assays were performed to investigate cell proliferation. Flow cytometry was conducted to analyze cell apoptosis. Dual-luciferase reporter assay was implemented to confirm the interaction among circ_EPB41, miR-24-3p, and BPNT1. Our data showed that circ_EPB41 and BPNT1 expression were downregulated in ARC tissues and UV-irradiated SRA01/04 cells as compared with normal anterior lens capsules and untreated SRA01/04 cells. Circ_EPB41 overexpression ameliorated the effects of UV irradiation on the proliferation and apoptosis of SRA01/04 cells. Besides, miR-24-3p, a target miRNA of circ_EPB41, attenuated circ_EPB41 introduction-mediated proliferation, and apoptosis of UV-irradiated SRA01/04 cells. MiR-24-3p regulated UV irradiation-induced effects by targeting BPNT1. Importantly, it was found that circ_EPB41 stimulated BPNT1 production by miR-24-3p. Taken together, the enforced expression of circ_EPB41 ameliorated UV irradiation-induced apoptosis of lens epithelial cells by miR-24-3p/BPNT1 pathway, providing us with a potential target for the therapy of UV-caused ARC.

MiR-22-3p inhibits fibrotic cataract through inactivation of HDAC6 and increase of α-tubulin acetylation

OBJECTIVES

Fibrotic cataract, including posterior capsule opacification (PCO) and anterior subcapsular cataract (ASC), renders millions of people visually impaired worldwide. However, the underlying mechanism remains poorly understood. Here, we report a miRNA-based regulatory pathway that controls pathological fibrosis of lens epithelium.

MATERIALS AND METHODS

Expression of miR-22-3p and histone deacetylase 6 (HDAC6) in normal and PCO patient samples were measured by qPCR. Human lens epithelial explants were treated with TGF-β2 in the presence or absence of miR-22-3p mimics or inhibitor. Cell proliferation was determined by MTS assay, and migration was tested by transwell assay. Expression of HDAC6 and EMT-related molecules were analysed by Western blot, qPCR and immunocytochemical experiments.

RESULTS

We identify miR-22-3p as a downregulated miRNA targeting HDAC6 in LECs during lens fibrosis and TGF-β2 treatment. Mechanistically, gain- and loss-of-function experiments in human LECs and lens epithelial explants reveal that miR-22-3p prevents proliferation, migration and TGF-β2 induced EMT of LECs via targeting HDAC6 and thereby promoting α-tubulin acetylation. Moreover, pharmacological targeting of HDAC6 deacetylase with Tubacin prevents fibrotic opaque formation through increasing α-tubulin acetylation under TGF-β2 stimulated conditions in both human lens epithelial explants and the whole rat lenses.

CONCLUSIONS

These findings suggest that miR-22-3p prevents lens fibrotic progression by targeting HDAC6 thereby promoting α-tubulin acetylation. The 'miR-22-HDAC6-α-tubulin (de)acetylation' signalling axis may be therapeutic targets for the treatment of fibrotic cataract.