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Dynamic Changes in the Expressions of Elastogenesis- and Elastinolysis-Associated Genes and Remodeling of the Elastin Network in Volume-Overloaded Heart

ABSTRACT: Background: In the remodeling process of the volume-overloaded heart, the extracellular matrix (ECM) may be dynamically modified to adapt to hemodynamic stress. We investigated the expression of ECM-related genes and modification of the elastin network in the remodeling process of the left ventricles (LVs) of rats with aortocaval fistulae. Methods and Findings: Gene array analysis identified 36 upregulated and 11 downregulated ECM-related genes during evolution from the compensated to the late decompensated phase. Ingenuity Pathway Analysis identified the formation of elastic fibers as an important biological function. Real-time PCR confirmed persistent upregulation of elastogenesis-associated genes, including elastin, lysyl oxidase, lysyl oxidase like-1, fibrillin 1, fibulin 2, versican and latent transforming growth factor beta binding protein 2 at various intervals. The expression levels and enzymatic activities of potent elastases, cathepsin S and cathepsin K increased during the early phase. Immunofluorescence confocal microscopy showed that the microstructure of the elastin network was preserved during the early phase, degraded during the compensated phase, partially repaired during the early decompensated phase, and reinforced during the late decompensated phase. Assessment of elastin concentrations in the LVs showed a consistent temporal pattern throughout the course. Conclusions: In the volume-overloaded heart, upregulation of potent elastases during the early phase and persistent upregulation of elastogenesis-related genes result in early degradation followed by repair and reinforcement of the elastin network of the LV. Remodeling of the elastin network may contribute to changes in the mechanical property of the volume-overloaded heart.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE97044 | GEO | 2018/03/31

REPOSITORIES: GEO

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Project description:Valve remodeling is a complex process involving extracellular matrix organization, development of trilaminar structures, and physical elongation of valve leaflets. However, the cellular and molecular mechanisms regulating valve remodeling and their roles in congenital valve disorders remain poorly understood. Semilunar valves and atrioventricular valves from healthy and age-matched human fetal hearts with pulmonary stenosis (PS) were collected. Single-Cell RNA-sequencing (scRNA-seq) was performed to determine the transcriptomic landscape of multiple valvular cell subtypes in valve remodeling and disease. Spatial localization of newly-identified cell subtypes was determined via immunofluorescence and RNA in situ hybridization. The molecular mechanisms mediating valve development was investigated utilizing primary human fetal valve interstitial cells (VICs) and endothelial cells (VECs). scRNA-seq analysis of healthy human fetal valves identified a novel APOE+ elastin-producing VIC subtype (Elastin-VIC) spatially located underneath VECs sensing the unidirectional flow. Knockdown of APOE in fetal VICs resulted in significant elastogenesis defects. In pulmonary valve with PS, we observed decreased expression of APOE and other genes regulating elastogenesis such as EMILIN1 and LOXL1, as well as elastin fragmentation. These findings suggested the crucial role of APOE in regulating elastogenesis during valve remodeling. Furthermore, cell-cell interaction analysis revealed that JAG1 from unidirectional VECs activates NOTCH signaling in Elastin-VICs through NOTCH3. In vitro Jag1 treatment in VICs increased the expression of elastogenesis-related genes and enhanced contractile functions with related gene expression. This was accompanied by activation of NOTCH signaling and elastogenesis observed in VICs co-cultured with VECs in the presence of unidirectional flow. Notably, we found that the JAG1-NOTCH3 signaling pair was drastically reduced in the PS valves. Lastly, we demonstrated that APOE is indispensable for JAG1-induced NOTCH activation in VICs, reinforcing the presence of a synergistic intrinsic and external regulatory network involving APOE and NOTCH signaling that is responsible for regulating elastogenesis during human valve remodeling. scRNA-seq analysis of human fetal valves identified a novel Elastin-VIC subpopulation, and revealed mechanism of intrinsic APOE and external NOTCH signaling from VECs sensing unidirectional flow in regulating elastogenesis during valve remodeling. These mechanisms may contribute to the pathogenesis of elastic malformation in congenital valve disease.

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Dynamic Changes in the Expressions of Elastogenesis- and Elastinolysis-Associated Genes and Remodeling of the Elastin Network in Volume-Overloaded Heart

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