c-Kit suppresses atherosclerosis in hyperlipidemic mice

Elevated c-kit expression in failed autologous arteriovenous fistulas in end-stage renal disease patients

BACKGROUND

Serum stem cell factor is elevated in end-stage renal disease (ESRD) patients. This study aimed to investigate the expression of the c-kit receptor, which is the specific membrane receptor of stem cell factor, in failed autologous arteriovenous fistulas (AVFs) in end-stage renal disease patients.

METHODS

A total of 14 ESRD patients with initial AVFs creation and 16 ESRD patients with reconstruction were enrolled in this study. Hematoxylin and eosin (H&E) and elastic Verhoeff-Van Gieson (EVG) staining were used for histomorphometric analyses. Immunohistochemistry was used to examine the expression of c-kit in the intima, and a correlation analysis was performed with the intimal area and the percentage of area stenosis. A double-label immunofluorescence method was used to explore the colocalization of c-kit with α-smooth muscle actin (α-SMA) and CD31. The expression of c-kit and the related PI3K/Akt signaling axis, including PI3K, P-PI3K, Akt, P-Akt473, P-Akt308, and mTOR, was measured by western blotting.

RESULTS

Internal elastic lamina (IEL) area, intimal area, percentage of area stenosis, and average optical density (AOD) of c-kit in the intima were significantly higher in the failed group than in the preoperative group (p ⩽ 0.001). The AOD of c-kit in the intima was positively correlated with the intimal area and the percentage of stenosis (intimal area: R = 0.744, p < 0.001; the percentage of stenosis: R = 0.923, p < 0.001). C-kit colocalized with α-SMA but not with CD31 in studies of c-kit target cells. Moreover, the levels of c-kit and P-PI3K, P-Akt473 and mTOR in the PI3K/Akt axis were also higher in the failed group than in the initial group (p < 0.05).

CONCLUSIONS

C-kit and related proteins associated with the PI3K/Akt pathway were elevated in failed AVFs among ESRD patients and that the expression level of c-kit in the intima correlates with the degree of AVF stenosis.

Endothelial microRNAs and long noncoding RNAs in cardiovascular ageing

Atherosclerosis and numerous other cardiovascular diseases develop in an age-dependent manner. The endothelial cells that line the vessel walls play an important role in the development of atherosclerosis. Non-coding RNA like microRNAs and long non-coding RNAs are known to play an important role in endothelial function and are implicated in the disease progression. Here, we summarize several microRNAs and long non-coding RNAs that are known to have an altered expression with endothelial aging and discuss their role in endothelial cell function and senescence. These processes contribute to aging-induced atherosclerosis development and by targeting the non-coding RNAs controlling endothelial cell function and senescence, atherosclerosis can potentially be attenuated.

Proteomics Analysis of Genetic Liability of Abdominal Aortic Aneurysm Identifies Plasma Neogenin and Kit Ligand: The ARIC Study

BACKGROUND

Genome-wide association studies have reported 23 gene loci related to abdominal aortic aneurysm (AAA)-a potentially lethal condition characterized by a weakened dilated vessel wall. This study aimed to identify proteomic signatures and pathways related to these risk loci to better characterize AAA genetic susceptibility.

METHODS

Plasma concentrations of 4870 proteins were determined using a DNA aptamer-based array. Linear regression analysis estimated the associations between the 23 risk alleles and plasma protein levels with adjustments for potential confounders in a race-stratified analysis of 1671 Black and 7241 White participants. Significant proteins were then evaluated for their prediction of clinical AAA (454 AAA events in 11 064 individuals), and those significantly associated with AAA were further interrogated using Mendelian randomization analysis.

RESULTS

Risk variants proximal to PSRC1-CELSR2-SORT1, PCIF1-ZNF335-MMP9, RP11-136O12.2/TRIB1, ZNF259/APOA5, IL6R, PCSK9, LPA, and APOE were associated with 118 plasma proteins in Whites and 59 were replicated in Black participants. Novel associations with clinical AAA incidence were observed for kit ligand (HR, 0.59 [95% CI, 0.42-0.82] for top versus first quintiles) and neogenin (HR, 0.64 [95% CI, 0.46-0.88]) over a median 21.2-year follow-up; neogenin was also associated with ultrasound-detected asymptomatic AAA (N=4295; 57 asymptomatic AAA cases). Mendelian randomization inverse variance weighted estimates suggested that AAA risk is promoted by lower levels of kit ligand (OR per SD=0.67; P=1.4×10-5) and neogenin (OR per SD=0.50; P=0.03).

CONCLUSIONS

Low levels of neogenin and kit ligand may be novel risk factors for AAA development in potentially causal pathways. These findings provide insights and potential targets to reduce AAA susceptibility.

Dihydromyricetin ameliorates osteogenic differentiation of human aortic valve interstitial cells by targeting c-KIT/interleukin-6 signaling pathway

Aims: Calcific aortic valve disease (CAVD) is a chronic cardiovascular disease with high morbidity that lacks effective pharmacotherapeutics. As a natural flavonoid extracted from Ampelopsis grossedentata, dihydromyricetin (DHM) has been shown to be effective in protecting against atherosclerosis; yet, the therapeutic role of DHM in CAVD remains poorly understood. Herein, we aimed to clarify the therapeutic implications of DHM in CAVD and the underlying molecular mechanisms in human valvular interstitial cells (hVICs).

Methods and Results: The protein levels of two known osteogenesis-specific genes (alkaline phosphatase, ALP; runt-related transcription factor 2, Runx2) and calcified nodule formation in hVICs were detected by Western blot and Alizarin Red staining, respectively. The results showed that DHM markedly ameliorated osteogenic induction medium (OM)–induced osteogenic differentiation of hVICs, as evidenced by downregulation of ALP and Runx2 expression and decreased calcium deposition. The SwissTargetPrediction database was used to identify the potential AVC-associated direct protein target of DHM. Protein–protein interaction (PPI) analysis revealed that c-KIT, a tyrosine-protein kinase, can act as a credible protein target of DHM, as evidenced by molecular docking. Mechanistically, DHM-mediated inhibition of c-KIT phosphorylation drove interleukin-6 (IL-6) downregulation in CAVD, thereby ameliorating OM-induced osteogenic differentiation of hVICs and aortic valve calcification progression.

Conclusion: DHM ameliorates osteogenic differentiation of hVICs by blocking the phosphorylation of c-KIT, thus reducing IL-6 expression in CAVD. DHM could be a viable therapeutic supplement to impede CAVD.

c-Kit expression in smooth muscle cells reduces atherosclerosis burden in hyperlipidemic mice

BACKGROUND AND AIMS

Increased receptor tyrosine kinase (RTK) activity has been historically linked to atherosclerosis. Paradoxically, we recently found that global deficiency in c-Kit function increased atherosclerosis in hyperlipidemic mice. This study aimed to investigate if such unusual atheroprotective phenotype depends upon c-Kit's function in smooth muscle cells (SMC).

METHODS

We studied atherosclerosis in a SMC-specific conditional knockout mice (Kit^SMC) and control littermate. Tamoxifen (TAM) and vehicle treated mice were fed high fat diet for 16 weeks before atherosclerosis assessment in the whole aorta using oil red staining. Smooth muscle cells were traced within the aortic sinus of conditional c-Kit tracing mice (Kit^SMC eYFP) and their control littermates (Kit^WT eYFP) by immunofluorescent confocal microscopy. We then performed RNA sequencing on primary SMC from c-Kit deficient and control mice, and identified significantly altered genes and pathways as a result of c-Kit deficiency in SMC.

RESULTS

Atherosclerosis significantly increased in Kit^SMC mice with respect to control groups. In addition, the loss of c-Kit in SMC increased plaque size and necrotic core area in the aortic sinus of hyperlipidemic mice. Smooth muscle cells from Kit^SMC eYFP mice were more prone to migrate and express foam cell markers (e.g., Mac2 and MCAM) than those from control littermate animals. RNAseq analysis showed a significant upregulation in genes associated with cell proliferation, migration, lipid metabolism, and inflammation secondary to the loss of Kit function in primary SMCs.

CONCLUSIONS

Loss of c-Kit increases SMC migration, proliferation, and expression of foam cell markers in atherosclerotic plaques from hyperlipidemic mice.

Transgelins: Cytoskeletal Associated Proteins Implicated in the Metastasis of Colorectal Cancer

Transgelins, including transgelin-1 (T-1), transgelin-2 (T-2), and transgelin-3 (T-3), are a family of actin-binding proteins (ABPs) that can alter the structure and morphology of the cytoskeleton. These proteins function by regulating migration, proliferation and apoptosis in many different cancers. Several studies have shown that in various types of tumor cells, including colorectal cancer (CRC) cells, and in the tumor microenvironment, the expression and biological effects of transgelins are diverse and may transform during tumor progression. Previous researches have demonstrated that transgelin levels are positively correlated with metastasis in CRC, and down-regulating their expression can inhibit this process. In advanced disease, T-1 is a tumor activator with increasing expression, and T-2 expression increases with the progression of CRC. Finally, T-3 is only expressed in neurons and is not associated with CRC. This evidence suggests that T-1 and T-2 are potential biomarkers and therapeutic targets for CRC metastasis.