Multiscale Analysis of Extracellular Matrix Remodeling in the Failing Heart

Rationale: Cardiac ECM (extracellular matrix) comprises a dynamic molecular network providing structural support to heart tissue function. Understanding the impact of ECM remodeling on cardiac cells during heart failure (HF) is essential to prevent adverse ventricular remodeling and restore organ functionality in affected patients. Objectives: We aimed to (1) identify consistent modifications to cardiac ECM structure and mechanics that contribute to HF and (2) determine the underlying molecular mechanisms. Methods and Results: We first performed decellularization of human and murine ECM (decellularized ECM) and then analyzed the pathological changes occurring in decellularized ECM during HF by atomic force microscopy, 2-photon microscopy, high-resolution 3-dimensional image analysis, and computational fluid dynamics simulation. We then performed molecular and functional assays in patient-derived cardiac fibroblasts based on YAP (yes-associated protein)-transcriptional enhanced associate domain (TEAD) mechanosensing activity and collagen contraction assays. The analysis of HF decellularized ECM resulting from ischemic or dilated cardiomyopathy, as well as from mouse infarcted tissue, identified a common pattern of modifications in their 3-dimensional topography. As compared with healthy heart, HF ECM exhibited aligned, flat, and compact fiber bundles, with reduced elasticity and organizational complexity. At the molecular level, RNA sequencing of HF cardiac fibroblasts highlighted the overrepresentation of dysregulated genes involved in ECM organization, or being connected to TGFβ1 (transforming growth factor β1), interleukin-1, TNF-α, and BDNF signaling pathways. Functional tests performed on HF cardiac fibroblasts pointed at mechanosensor YAP as a key player in ECM remodeling in the diseased heart via transcriptional activation of focal adhesion assembly. Finally, in vitro experiments clarified pathological cardiac ECM prevents cell homing, thus providing further hints to identify a possible window of action for cell therapy in cardiac diseases. Conclusions: Our multiparametric approach has highlighted repercussions of ECM remodeling on cell homing, cardiac fibroblast activation, and focal adhesion protein expression via hyperactivated YAP signaling during HF.

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The AP-1 Transcription Factor Fosl-2 Regulates Autophagy in Cardiac Fibroblasts during Myocardial Fibrogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms22041861 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1861

Author(s):

Jemima Seidenberg ◽

Mara Stellato ◽

Amela Hukara ◽

Burkhard Ludewig ◽

Karin Klingel ◽

...

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Type I Collagen ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Smooth Muscle Actin ◽

Beclin 1 ◽

Type I ◽

Alpha Smooth Muscle Actin

Background: Pathological activation of cardiac fibroblasts is a key step in development and progression of cardiac fibrosis and heart failure. This process has been associated with enhanced autophagocytosis, but molecular mechanisms remain largely unknown. Methods and Results: Immunohistochemical analysis of endomyocardial biopsies showed increased activation of autophagy in fibrotic hearts of patients with inflammatory cardiomyopathy. In vitro experiments using mouse and human cardiac fibroblasts confirmed that blockade of autophagy with Bafilomycin A1 inhibited fibroblast-to-myofibroblast transition induced by transforming growth factor (TGF)-β. Next, we observed that cardiac fibroblasts obtained from mice overexpressing transcription factor Fos-related antigen 2 (Fosl-2tg) expressed elevated protein levels of autophagy markers: the lipid modified form of microtubule-associated protein 1A/1B-light chain 3B (LC3BII), Beclin-1 and autophagy related 5 (Atg5). In complementary experiments, silencing of Fosl-2 with antisense GapmeR oligonucleotides suppressed production of type I collagen, myofibroblast marker alpha smooth muscle actin and autophagy marker Beclin-1 in cardiac fibroblasts. On the other hand, silencing of either LC3B or Beclin-1 reduced Fosl-2 levels in TGF-β-activated, but not in unstimulated cells. Using a cardiac hypertrophy model induced by continuous infusion of angiotensin II with osmotic minipumps, we confirmed that mice lacking either Fosl-2 (Ccl19CreFosl2flox/flox) or Atg5 (Ccl19CreAtg5flox/flox) in stromal cells were protected from cardiac fibrosis. Conclusion: Our findings demonstrate that Fosl-2 regulates autophagocytosis and the TGF-β-Fosl-2-autophagy axis controls differentiation of cardiac fibroblasts. These data provide a new insight for the development of pharmaceutical targets in cardiac fibrosis.

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Proline-rich tyrosine kinase 2 mediates transforming growth factor-beta-induced hepatic stellate cell activation and liver fibrosis

Scientific Reports ◽

10.1038/s41598-020-78056-0 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jonghwa Kim ◽

Wonseok Kang ◽

So Hee Kang ◽

Su Hyun Park ◽

Ji Young Kim ◽

...

Keyword(s):

Liver Fibrosis ◽

Tyrosine Kinase ◽

Focal Adhesion ◽

Transforming Growth Factor ◽

Family Members ◽

Type I ◽

Tyrosine Kinase 2 ◽

The Impact ◽

Tgf Β1

AbstractHepatic fibrogenesis is characterized by activation of hepatic stellate cells (HSCs) and accumulation of extracellular matrix (ECM). The impact of ECM on TGF-β-mediated fibrogenic signaling pathway in HSCs has remained obscure. We studied the role of non-receptor tyrosine kinase focal adhesion kinase (FAK) family members in TGF-β-signaling in HSCs. We used a CCl4-induced liver fibrosis mice model to evaluate the effect of FAK family kinase inhibitors on liver fibrosis. RT-PCR and Western blot were used to measure the expression of its target genes; α-SMA, collagen, Nox4, TGF-β1, Smad7, and CTGF. Pharmacological inhibitors, siRNA-mediated knock-down, and plasmid-based overexpression were adopted to modulate the function and the expression level of proteins. Association of PYK2 activation with liver fibrosis was confirmed in liver samples from CCl4-treated mice and patients with significant fibrosis or cirrhosis. TGF-β treatment up-regulated expression of α-SMA, type I collagen, NOX4, CTGF, TGF-β1, and Smad7 in LX-2 cells. Inhibition of FAK family members suppressed TGF-β-mediated fibrogenic signaling. SiRNA experiments demonstrated that TGF-β1 and Smad7 were upregulated via Smad-dependent pathway through FAK activation. In addition, CTGF induction was Smad-independent and PYK2-dependent. Furthermore, RhoA activation was essential for TGF-β-mediated CTGF induction, evidenced by using ROCK inhibitor and dominant negative RhoA expression. We identified that TGF-β1-induced activation of PYK2-Src-RhoA triad leads to YAP/TAZ activation for CTGF induction in liver fibrosis. These findings provide new insights into the role of focal adhesion molecules in liver fibrogenesis, and targeting PYK2 may be an attractive target for developing novel therapeutic strategies for the treatment of liver fibrosis.

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Abstract 292: TRPA1 Promoting Myofibroblast Differentiation Mediate Pressure Overload-Induced Cardiac Fibrosis

Circulation ◽

10.1161/circ.138.suppl_2.292 ◽

2018 ◽

Vol 138 (Suppl_2) ◽

Author(s):

Shuang Li ◽

Dong Han ◽

Dachun Yang

Keyword(s):

Knockout Mice ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Transient Receptor Potential ◽

Transforming Growth Factor ◽

Ventricular Remodeling ◽

Cardiac Fibroblasts ◽

Gene Transfection ◽

Pressure Overload

Background: Hypertensive ventricular remodeling is a common cause of heart failure. Activation and accumulation of cardiac fibroblasts is the key contributors to this progression. Our previous studies indicate that transient receptor potential ankyrin 1 (TRPA1), a Ca 2+ channel necessary and sufficient, play a prominent role in ventricular remodeling. However, the molecular mechanisms regulating remain poorly understood. Methods: We used TRPA1 agonists cinnamaldehyde (CA) pretreatment and TRPA1 knockout mice to understand the role of TRPA1 in ventricular remodeling of hypertensive heart. We also examine the mechanisms through gene transfection and in vitro experiments. Results: TRPA1 overexpression fully activated myofibroblast transformation, while fibroblasts lacking TRPA1 were refractory to transforming growth factor β (TGF-β) -induced transdifferentiation. TRPA1 knockout mice showed hypertensive ventricular remodeling reversal following pressure overload. We found that the TGF-β induced TRPA1 expression through calcineurin-NFAT-Dyrk1A signaling pathway via the TRPA1 promoter. Once induced, TRPA1 activates the Ca 2+ -responsive protein phosphatase calcineurin, which itself induced myofibroblast transdifferentiation. Moreover, inhibition of calcineurin prevented TRPA1-dependent transdifferentiation. Conclusion: Our study provides the first evidence that TRPA1 regulation in cardiac fibroblasts transformation in response to hypertensive stimulation. The results suggesting a comprehensive pathway for myofibroblast formation in conjunction with TGF-β, Calcineurin, NFAT and Dyrk1A. Furthermore, these data indicate that negative modulation of cardiac fibroblast TRPA1 may represent a therapeutic strategy against hypertensive cardiac remodeling.

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Abstract 126: High Efficiency Reprogramming of Fibroblasts Into Cardiomyocytes Requires Suppression of Pro-fibrotic Signaling

Circulation Research ◽

10.1161/res.117.suppl_1.126 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Kunhua Song ◽

Yuanbiao Zhao ◽

Pilar Londono ◽

Emily Sharpe ◽

Joshua R Clair ◽

...

Keyword(s):

Molecular Mechanisms ◽

High Efficiency ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Rho Kinase ◽

Transforming Growth Factor Β ◽

Direct Reprogramming ◽

Cardiac Gene Expression ◽

Cardiac Gene ◽

Kinetics Of

The mammalian heart is composed of ~30% cardiomyocytes which have limited capacity to regenerate and ~70% non-cardiomyocytes including endothelial cells and cardiac fibroblasts. Direct reprogramming of fibroblasts into cardiomyocytes by forced expression of cardiomyogenic transcription factors, GMT (GATA4, Mef2C, Tbx5) or GHMT (GATA4, Hand2, Mef2C, Tbx5), has recently been demonstrated, suggesting a novel therapeutic strategy for cardiac repair. Despite extensive efforts, the efficiency of direct reprogramming of embryonic or adult fibroblasts into cardiomyocytes has yet to exceed 20%, or 0.1% respectively, leading many in the field to question the clinical translatability of this method. Here, we demonstrate that pro-fibrotic signaling events governed by transforming growth factor-β (TGF-β) and Rho kinase (ROCK) are concomitantly activated in GHMT-expressing fibroblasts, leading to potent suppression of cardiac reprogramming ( Figure 1 ). Remarkably, pharmacological inhibition of TGF-β, or ROCK leads to conversion of ≥ 60% of fibroblasts into highly functional cardiomyocytes, displaying global cardiac gene expression, spontaneous contractility, action potentials and calcium transients. Furthermore, inhibition of TGF-β, or ROCK dramatically enhances the kinetics of cardiac reprogramming, with spontaneously contracting cardiomyocytes emerging in less than two weeks, as opposed to 4 weeks with GHMT alone. These findings provide new insights into the molecular mechanisms underlying cardiac conversion of fibroblasts, and should enhance efforts to generate cardiomyocytes for clinical applications.

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Featured Article: TGF-β1 dominates extracellular matrix rigidity for inducing differentiation of human cardiac fibroblasts to myofibroblasts

Experimental Biology and Medicine ◽

10.1177/1535370218761628 ◽

2018 ◽

Vol 243 (7) ◽

pp. 601-612 ◽

Cited By ~ 15

Author(s):

Nathan Cho ◽

Shadi E Razipour ◽

Megan L McCain

Keyword(s):

Extracellular Matrix ◽

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Myofibroblast Differentiation ◽

Matrix Rigidity ◽

Growth Factor Beta ◽

Human Cardiac Fibroblasts ◽

Tgf Β1

Cardiac fibroblasts and their activated derivatives, myofibroblasts, play a critical role in wound healing after myocardial injury and often contribute to long-term pathological outcomes, such as excessive fibrosis. Thus, defining the microenvironmental factors that regulate the phenotype of cardiac fibroblasts and myofibroblasts could lead to new therapeutic strategies. Both chemical and biomechanical cues have previously been shown to induce myofibroblast differentiation in many organs and species. For example, transforming growth factor beta 1, a cytokine secreted by neutrophils, and rigid extracellular matrix environments have both been shown to promote differentiation. However, the relative contributions of transforming growth factor beta 1 and extracellular matrix rigidity, two hallmark cues in many pathological myocardial microenvironments, to the phenotype of human cardiac fibroblasts are unclear. We hypothesized that transforming growth factor beta 1 and rigid extracellular matrix environments would potentially have a synergistic effect on the differentiation of human cardiac fibroblasts to myofibroblasts. To test this, we seeded primary human adult cardiac fibroblasts onto coverslips coated with polydimethylsiloxane of various elastic moduli, introduced transforming growth factor beta 1, and longitudinally quantified cell phenotype by measuring expression of α-smooth muscle actin, the most robust indicator of myofibroblasts. Our data indicate that, although extracellular matrix rigidity influenced differentiation after one day of transforming growth factor beta 1 treatment, ultimately transforming growth factor beta 1 superseded extracellular matrix rigidity as the primary regulator of myofibroblast differentiation. We also measured expression of POSTN, FAP, and FSP1, proposed secondary indicators of fibroblast/myofibroblast phenotypes. Although these genes partially trended with α-smooth muscle actin expression, they were relatively inconsistent. Finally, we demonstrated that activated myofibroblasts incompletely revert to a fibroblast phenotype after they are re-plated onto new surfaces without transforming growth factor beta 1, suggesting differentiation is partially reversible. Our results provide new insights into how microenvironmental cues affect human cardiac fibroblast differentiation in the context of myocardial pathology, which is important for identifying effective therapeutic targets and dictating supporting cell phenotypes for engineered human cardiac disease models. Impact statement Heart disease is the leading cause of death worldwide. Many forms of heart disease are associated with fibrosis, which increases extracellular matrix (ECM) rigidity and compromises cardiac output. Fibrotic tissue is synthesized primarily by myofibroblasts differentiated from fibroblasts. Thus, defining the cues that regulate myofibroblast differentiation is important for understanding the mechanisms of fibrosis. However, previous studies have focused on non-human cardiac fibroblasts and have not tested combinations of chemical and mechanical cues. We tested the effects of TGF-β1, a cytokine secreted by immune cells after injury, and ECM rigidity on the differentiation of human cardiac fibroblasts to myofibroblasts. Our results indicate that differentiation is initially influenced by ECM rigidity, but is ultimately superseded by TGF-β1. This suggests that targeting TGF-β signaling pathways in cardiac fibroblasts may have therapeutic potential for attenuating fibrosis, even in rigid microenvironments. Additionally, our approach can be leveraged to engineer more precise multi-cellular human cardiac tissue models.

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Targeting extracellular matrix stiffness to attenuate disease: From molecular mechanisms to clinical trials

Science Translational Medicine ◽

10.1126/scitranslmed.aao0475 ◽

2018 ◽

Vol 10 (422) ◽

pp. eaao0475 ◽

Cited By ~ 134

Author(s):

Marsha C. Lampi ◽

Cynthia A. Reinhart-King

Keyword(s):

Extracellular Matrix ◽

Clinical Trials ◽

Cellular Response ◽

Molecular Mechanisms ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Therapeutic Interventions ◽

Target Tissue ◽

Matrix Stiffness ◽

Extracellular Matrix Stiffness

Tissues stiffen during aging and during the pathological progression of cancer, fibrosis, and cardiovascular disease. Extracellular matrix stiffness is emerging as a prominent mechanical cue that precedes disease and drives its progression by altering cellular behaviors. Targeting extracellular matrix mechanics, by preventing or reversing tissue stiffening or interrupting the cellular response, is a therapeutic approach with clinical potential. Major drivers of changes to the mechanical properties of the extracellular matrix include phenotypically converted myofibroblasts, transforming growth factor β (TGFβ), and matrix cross-linking. Potential pharmacological interventions to overcome extracellular matrix stiffening are emerging clinically. Aside from targeting stiffening directly, alternative approaches to mitigate the effects of increased matrix stiffness aim to identify and inhibit the downstream cellular response to matrix stiffness. Therapeutic interventions that target tissue stiffening are discussed in the context of their limitations, preclinical drug development efforts, and clinical trials.

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Natural Sulfur-Containing Compounds: An Alternative Therapeutic Strategy against Liver Fibrosis

Cells ◽

10.3390/cells8111356 ◽

2019 ◽

Vol 8 (11) ◽

pp. 1356 ◽

Cited By ~ 13

Author(s):

Milito ◽

Brancaccio ◽

D’Argenio ◽

Castellano

Keyword(s):

Extracellular Matrix ◽

Growth Factor ◽

Liver Fibrosis ◽

Hepatic Fibrosis ◽

Molecular Mechanisms ◽

Transforming Growth Factor ◽

Extracellular Matrix Proteins ◽

Matrix Proteins ◽

Sulfur Containing ◽

Sulfur Containing Compounds

Liver fibrosis is a pathophysiologic process involving the accumulation of extracellular matrix proteins as collagen deposition. Advanced liver fibrosis can evolve in cirrhosis, portal hypertension and often requires liver transplantation. At the cellular level, hepatic fibrosis involves the activation of hepatic stellate cells and their transdifferentiation into myofibroblasts. Numerous pro-fibrogenic mediators including the transforming growth factor-β1, the platelet-derived growth factor, endothelin-1, toll-like receptor 4, and reactive oxygen species are key players in this process. Knowledge of the cellular and molecular mechanisms underlying hepatic fibrosis development need to be extended to find novel therapeutic strategies. Antifibrotic therapies aim to inhibit the accumulation of fibrogenic cells and/or prevent the deposition of extracellular matrix proteins. Natural products from terrestrial and marine sources, including sulfur-containing compounds, exhibit promising activities for the treatment of fibrotic pathology. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans are largely unknown. This review aims to provide a reference collection on experimentally tested natural anti-fibrotic compounds, with particular attention on sulfur-containing molecules. Their chemical structure, sources, mode of action, molecular targets, and pharmacological activity in the treatment of liver disease will be discussed.

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Cell-derived extracellular matrix-coated silk fibroin scaffold for cardiogenesis of brown adipose stem cells through modulation of TGF-β pathway

Regenerative Biomaterials ◽

10.1093/rb/rbaa011 ◽

2020 ◽

Vol 7 (4) ◽

pp. 403-412

Author(s):

Wei Liu ◽

Yanfeng Sun ◽

Xiaohui Dong ◽

Qi Yin ◽

Huimin Zhu ◽

...

Keyword(s):

Stem Cells ◽

Extracellular Matrix ◽

Silk Fibroin ◽

Transforming Growth Factor ◽

Troponin T ◽

Cardiac Fibroblasts ◽

Adipose Stem Cells ◽

Silk Fibroin Scaffold ◽

Brown Adipose

Abstract The cell-derived extracellular matrix (ECM)-modified scaffolds have advantages of mimic tissue specificity and been thought to better mimic the native cellular microenvironment in vitro. ECM derived from cardiac fibroblasts (CFs) are considered as key elements that provide a natural cell growth microenvironment and change the fate of cardiomyocytes (CMs). Here, a new hybrid scaffold is designed based on silk fibroin (SF) scaffold and CFs-derived ECM. CFs were seeded on the SF scaffold for 10 days culturing and decellularized to produce CFs-derived ECM-coated SF scaffold. The results showed that the cell-derived ECM-modified silk fibroin scaffold material contained collagen, laminin, fibronectin and other ECM components with myocardial-like properties. Further to explore its effects on brown adipose stem cells (BASCs) differentiation into CMs. We found that the CF-derived ECM-coated scaffold also increased the expression of CM-specific proteins (e.g. cardiac troponin T and α-actinin) of BASCs. Notably, the β1-integrin-dependent transforming growth factor-β1 signaling pathway was also involved in the regulation of CF-derived ECM by promoting the differentiation of BASCs into CMs. Overall, these findings provide insights into the bionic manufacturing of engineered cardiac tissues (ECTs) and establish a theoretical basis for the construction of ECTs.

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Pirfenidone exhibits cardioprotective effects by regulating myocardial fibrosis and vascular permeability in pressure-overloaded hearts

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00137.2015 ◽

2015 ◽

Vol 309 (3) ◽

pp. H512-H522 ◽

Cited By ~ 44

Author(s):

Kiyoshi Yamagami ◽

Toru Oka ◽

Qi Wang ◽

Takamaru Ishizu ◽

Jong-Kook Lee ◽

...

Keyword(s):

Heart Failure ◽

Endothelial Cells ◽

Vascular Permeability ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Chronic Phase ◽

Vehicle Group

Although cardiac fibrosis causes heart failure, its molecular mechanisms remain elusive. In this study, we investigated the mechanisms of cardiac fibrosis and examined the effects of the antifibrotic drug pirfenidone (PFD) on chronic heart failure. To understand the responsible mechanisms, we generated an in vivo pressure-overloaded heart failure model via transverse aortic constriction (TAC) and examined the effects of PFD on chronic-phase cardiac fibrosis and function. In the vehicle group, contractile dysfunction and left ventricle fibrosis progressed further from 4 to 8 wk after TAC but were prevented by PFD treatment beginning 4 wk after TAC. We isolated cardiac fibroblasts and vascular endothelial cells from the left ventricles of adult male mice and investigated the cell-type-specific effects of PFD. Transforming growth factor-β induced upregulated collagen 1 expression via p38 phosphorylation and downregulated claudin 5 (Cldn5) expression in cardiac fibroblasts and endothelial cells, respectively; both processes were inhibited by PFD. Moreover, PFD inhibited changes in the collagen 1 and Cldn5 expression levels, resulting in reduced fibrosis and serum albumin leakage into the interstitial space during the chronic phase in TAC hearts. In conclusion, PFD inhibited cardiac fibrosis by suppressing both collagen expression and the increased vascular permeability induced by pressure overload.

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Retinitis Pigmentosa Results in Neurodegeneration Concomitant With Neuroinflammation, Extracellular Matrix Disorganization and the Upregulation of Neuroprotective Pathways in Glial Cells and Neurons

10.21203/rs.3.rs-101559/v1 ◽

2020 ◽

Author(s):

Christina B. Bielmeier ◽

Saskia Roth ◽

Sabrina I. Schmitt ◽

Stefaniya K. Boneva ◽

Anja Schlecht ◽

...

Keyword(s):

Extracellular Matrix ◽

Retinitis Pigmentosa ◽

Retinal Degeneration ◽

Molecular Mechanisms ◽

Genetic Model ◽

Immunofluorescent Staining ◽

System Response ◽

Photoreceptor Degeneration ◽

The Impact

Abstract BackgroundHereditary retinal degenerations like retinitis pigmentosa (RP) are amongst the leading causes of blindness in younger patients. To enable in vivo investigation of cellular and molecular mechanisms responsible for photoreceptor cell death and to allow testing of therapeutic strategies that could prevent retinal degeneration, animal models have been created. Here, we in-depth characterized the transgenic VPP mouse model, a genetic model for autosomal dominant RP. MethodsWe examined the degree of photoreceptor degeneration and studied the impact of the VPP transgene-induced retinal degeneration on the transcriptome level of the retina using next generation RNA sequencing (RNASeq) analyses followed by weighted correlation network analysis (WGCNA). We furthermore identified cellular subpopulations responsible for some of the observed dysregulations using in situ hybridizations, immunofluorescent staining and 3D reconstruction. ResultsOne month-old VPP mice showed a significantly higher number of apoptotic photoreceptor cells that resulted in a significantly thinner ONL in three months-old VPP mice, concomitant with an increase in reactivity of microglia and Müller cells. By RNASeq analysis we identified 9,256 dysregulated genes and six significantly associated gene modules in the subsequently performed WGCNA. Gene ontology enrichment showed, amongst others, dysregulation of TGF-β regulated extracellular matrix organization, factors of the (ocular) immune system/response and apoptosis. ConclusionThe predominant effect pointed towards induction of neuroinflammation and the upregulation of neuroprotective pathways like TGF-β, G-protein activated and VEGF signaling that were significantly associated with the VPP transgene-induced photoreceptor degeneration. Thus, modulation of these processes might represent new therapeutic options to delay the degeneration of photoreceptors in diseases like RP.

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