Shear-dependent fibrillogenesis of fibronectin: Impact of platelet integrins and actin cytoskeleton

Low shear-induced fibrillar fibronectin: comparative analyses of morphologies and cellular effects on bovine aortic endothelial cell adhesion and proliferation

Wall shear stress (WSS) is a critical factor in vascular biology, and both high and low WSS are implicated in atherosclerosis. Fibronectin (FN) is a key extracellular matrix protein that plays an important role in cell activities. Under high shear stress, plasma FN undergoes fibrillogenesis; however, its behavior under low shear stress remains unclear. This study aimed to investigate the formation ofin vitrocell-free fibrillar FN (FFN) under low shear rate conditions and its effect on bovine aortic endothelial cell behavior. FN (500µg ml-1) was perfused through slide chambers at three flow rates (0.16 ml h-1, 0.25 ml h-1, and 0.48 ml h-1), corresponding to low shear rates of 0.35 s-1, 0.55 s-1, and 1.05 s-1, respectively, for 4 h at room temperature. The formed FN matrices were observed using fluorescence microscopy and scanning electron microscopy. Under low shear rates, distinct FN matrix structures were observed. FFN0.48 formed immense fibrils with smooth surfaces, FFN0.25 formed a matrix with a rough surface, and FFN16 exhibited nodular structures. FFN0.25 supported cell activities to a greater extent than native FN and other FFN surfaces. Our study suggests that abnormally low shear conditions impact FN structure and function and enhance the understanding of FN fibrillogenesis in vascular biology, particularly in atherosclerosis.

Identification of Parkinson's disease-related pathways and potential risk factors

Objective

To identify Parkinson’s disease (PD)-associated deregulated pathways and genes, to further elucidate the pathogenesis of PD.

Methods

Dataset GSE100054 was downloaded from the Gene Expression Omnibus, and differentially expressed genes (DEGs) in PD samples were identified. Functional enrichment analyses were conducted for the DEGs. The top 10 hub genes in the protein–protein interaction (PPI) network were screened out and used to construct a support vector machine (SVM) model. The expression of the top 10 genes was then validated in another dataset, GSE46129, and a clinical patient cohort.

Results

A total of 333 DEGs were identified. The DEGs were clustered into two gene sets that were significantly enriched in 12 pathways, of which 8 were significantly deregulated in PD, including cytokine–cytokine receptor interaction, gap junction, and actin cytoskeleton regulation. The signature of the top 10 hub genes in the PPI network was used to construct the SVM model, which had high performance for predicting PD. Of the 10 genes, GP1BA, GP6, ITGB5, and P2RY12 were independent risk factors of PD.

Conclusion

Genes such as GP1BA, GP6, P2RY12, and ITGB5 play critical roles in PD pathology through pathways including cytokine−cytokine receptor interaction, gap junctions, and actin cytoskeleton regulation.

Mouse transient receptor potential channel type 6 selectively regulates agonist-induced platelet function

While changes in intracellular calcium levels is a central step in platelet activation and thrombus formation, the contribution and mechanism of receptor-operated calcium entry (ROCE) via transient receptor potential channels (TRPCs) in platelets remains poorly defined. In previous studies, we have shown that TRPC6 regulates hemostasis and thrombosis, in mice. In the present studies, we employed a knockout mouse model system to characterize the role of TRPC6 in ROCE and platelet activation. It was observed that the TRPC6 deletion (Trpc6^−/−) platelets displayed impaired elevation of intracellular calcium, i.e., defective ROCE. Moreover, these platelets also exhibited defects in a host of functional responses, namely aggregation, granule secretion, and integrin αIIbβ3. Interestingly, the aforementioned defects were specific to the thromboxane receptor (TPR), as no impaired responses were observed in response to ADP or the thrombin receptor-activating peptide 4 (TRAP4). The defect in ROCE in the Trpc6^−/− was also observed with 1-oleoyl-2-acetyl-sn-glycerol (OAG). Finally, our studies also revealed that TRPC6 regulates clot retraction. Taken together, our findings demonstrate that TRPC6 directly regulates TPR-dependent ROCE and platelet function. Thus, TRPC6 may serve as a novel target for the therapeutic management of thrombotic diseases.

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TRPC6 regulates TPR-mediated/receptor-operated calcium entry.

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TRPC6 regulates TPR-dependent platelet aggregation, secretion and integrin activation.

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TRPC6 regulates clot retraction.

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TRPC6 expression levels are age-dependent in platelets.