Endothelial discoidin domain receptor 1 senses flow to modulate YAP activation

DDR1 in pancreatic adenocarcinoma: unraveling the mechanisms of immune exclusion

BACKGROUND

Pancreatic adenocarcinoma (PAAD) is a deadly cancer marked by extensive collagen deposition and limited response to immunotherapy. Discoidin domain receptor1 (DDR1), part of the transmembrane receptor tyrosine kinase family, is linked to inflammation regulation and immune cell infiltration. However, its role in controlling cytokines and chemokines in the microenvironment of PAAD is still unclear.

METHODS

Initially, RNA sequencing data from TCGA were utilized to investigate the expression of DDR1. Subsequently, the relationship between DDR1 and immune infiltration was examined through Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA) analysis, in conjunction with ssGSEA Immunoanalysis. Lastly, the effect of DDR1 on the malignant characteristics of PAAD cells was examined through in vitro experimentation, employing various techniques such as the CCK8 assay, colony formation assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The research revealed a notable increase in the expression level of DDR1 in PAAD. Subsequent analysis indicated a correlation between the differential expression of DDR1 with chemokines and immune infiltration. Additionally, cellular experiments demonstrated that the downregulation of DDR1 led to enhanced expression of chemokines CCL4, CCL5 and CXCL10.

CONCLUSION

DDR1 is linked to tumor immune infiltration, and the knockout of DDR1 results in the upregulation of chemokines CCL4, CCL5 and CXCL10 in Pan02 PAAD cells.

Kindlin-2 Phase Separation in Response to Flow Controls Vascular Stability

BACKGROUND

Atheroprotective shear stress preserves endothelial barrier function, while atheroprone shear stress enhances endothelial permeability. Yet, the underlying mechanisms through which distinct flow patterns regulate EC integrity remain to be clarified. This study aimed to investigate the involvement of Kindlin-2, a key component of focal adhesion and endothelial adherens junctions crucial for regulating endothelial cell (EC) integrity and vascular stability.

METHODS

Mouse models of atherosclerosis in EC-specific Kindlin-2 knockout mice (Kindlin-2iΔEC) were used to study the role of Kindlin-2 in atherogenesis. Pulsatile shear (12±4 dynes/cm2) or oscillatory shear (0.5±4 dynes/cm2) were applied to culture ECs. Live-cell imaging, fluorescence recovery after photobleaching assay, and OptoDroplet assay were used to study the liquid-liquid phase separation (LLPS) of Kindlin-2. Co-immunoprecipitation, mutagenesis, proximity ligation assay, and transendothelial electrical resistance assay were used to explore the underlying mechanism of flow-regulated Kindlin-2 function.

RESULTS

We found that Kindlin-2 localization is altered under different flow patterns. Kindlin-2iΔEC mice showed heightened vascular permeability. Kindlin-2iΔEC were bred onto ApoE-/- mice to generate Kindlin-2iΔEC; ApoE-/- mice, which displayed a significant increase in atherosclerosis lesions. In vitro data showed that in ECs, Kindlin-2 underwent LLPS, a critical process for proper focal adhesion assembly, maturation, and junction formation. Mass spectrometry analysis revealed that oscillatory shear increased arginine methylation of Kindlin-2, catalyzed by PRMT5 (protein arginine methyltransferase 5). Functionally, arginine hypermethylation inhibits Kindlin-2 LLPS, impairing focal adhesion assembly and junction maturation. Notably, we identified R290 of Kindlin-2 as a crucial residue for LLPS and a key site for arginine methylation. Finally, pharmacologically inhibiting arginine methylation reduces EC activation and plaque formation.

CONCLUSIONS

Collectively, our study elucidates that mechanical force induces arginine methylation of Kindlin-2, thereby regulating vascular stability through its impact on Kindlin-2 LLPS. Targeting Kindlin-2 arginine methylation emerges as a promising hemodynamic-based strategy for treating vascular disorders and atherosclerosis.

Force-sensing protein expression in response to cardiovascular mechanotransduction

Force-sensing biophysical cues in microenvironment, including extracellular matrix performances, stretch-mediated mechanics, shear stress and flow-induced hemodynamics, have a significant influence in regulating vascular morphogenesis and cardiac remodeling by mechanotransduction. Once cells perceive these extracellular mechanical stimuli, Piezo activation promotes calcium influx by forming integrin-adhesion-coupling receptors. This induces robust contractility of cytoskeleton structures to further transmit biomechanical alternations into nuclei by regulating Hippo-Yes associated protein (YAP) signaling pathway between cytoplasmic and nuclear translocation. Although biomechanical stimuli are widely studied in cardiovascular diseases, the expression of force-sensing proteins in response to cardiovascular mechanotransduction has not been systematically concluded. Therefore, this review will summarize the force-sensing Piezo, cytoskeleton and YAP proteins to mediate extracellular mechanics, and also give the prominent emphasis on intrinsic connection of these mechanical proteins and cardiovascular mechanotransduction. Extensive insights into cardiovascular mechanics may provide some new strategies for cardiovascular clinical therapy.

Collagen VIII in vascular diseases

Collagens have dual functions in the extracellular matrix (ECM), acting as both structural components and signaling molecules in matricellular communication. Although collagen molecules share a common triple helix motif, the supramolecular organization helps classify them into nearly 30 different types of collagens. Collagen type VIII is a non-fibrillar, short-chain, network-forming collagen that is expressed throughout the vasculature. Collagen VIII expression is aberrant in cardiovascular, lung, and renal disease, as well as in several different types of cancer. It plays active roles in angiogenesis, vessel injury repair, maintenance of arterial compliance, atherosclerotic plaque formation and stability modulation, fibrosis, and ECM remodeling. This review presents an overview of the characteristics of collagen VIII in vascular-related disorders, from clinical significance to laboratory studies, with a major focus on highlighting the signaling properties of collagen VIII in the vascular ECM. The expression patterns of collagen VIII in human diseases and experimental animal models highlight the protein's important yet underexplored functions. A deeper understanding of its mechanisms and downstream signaling pathways may pave the way for translational and tissue engineering applications of collagen VIII.

Mechanosensory entities and functionality of endothelial cells

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations.

Exploring the relationship between hemodynamics and the immune microenvironment in carotid atherosclerosis: Insights from CFD and CyTOF technologies

Carotid atherosclerosis is a major cause of stroke. Hemodynamic forces, such as shear stress and oscillatory shear, play an important role in the initiation and progression of atherosclerosis. The alteration of the immune microenvironment is the fundamental pathological mechanism by which diverse external environmental factors impact the formation and progression of plaques. However, Current research on the relationship between hemodynamics and immunity in atherosclerosis still lack of comprehensive understanding. In this study, we combined computational fluid dynamics (CFD) and Mass cytometry (CyTOF) technologies to explore the changes in the immune microenvironment within plaques under different hemodynamic conditions. Our results indicated that neutrophils were enriched in adverse flow environments. M2-like CD163+CD86+ macrophages were predominantly enriched in high WSS and low OSI environments, while CD163-CD14+ macrophages were enriched in low WSS and high OSI environments. Functional analysis further revealed T cell pro-inflammatory activation and dysregulation in modulation, along with an imbalance in M1-like/M2-like macrophages, suggesting their potential involvement in the progression of atherosclerotic lesions mediated by adverse flow patterns. Our study elucidated the potential mechanisms by which hemodynamics regulated the immune microenvironment within plaques, providing intervention targets for future precision therapies.

DDR1-targeted therapies: current limitations and future potential

Discoidin domain receptor (DDR)-1 has a crucial role in regulating vital processes, including cell differentiation, proliferation, adhesion, migration, invasion, and matrix remodeling. Overexpression or activation of DDR1 in various pathological scenarios makes it a potential therapeutic target for the treatment of cancer, fibrosis, atherosclerosis, and neuropsychiatric, psychiatric, and neurodegenerative disorders. In this review, we summarize current therapeutic approaches targeting DDR1 from a medicinal chemistry perspective. Furthermore, we analyze factors other than issues of low selectivity and risk of resistance, contributing to the infrequent success of DDR1 inhibitors. The complex interplay between DDR1 and the extracellular matrix (ECM) necessitates additional validation, given that DDR1 might exhibit complex and synergistic interactions with other signaling molecules during ECM regulation. The mechanisms involved in DDR1 regulation in cancer and inflammation-related diseases also remain unknown.

Improving impact of heparan sulfate on the endothelial glycocalyx abnormalities in atherosclerosis as revealed by glycan-protein interactome

Endothelial dysfunction induced by oxidative stress is an early predictor of atherosclerosis, which can cause various cardiovascular diseases. The glycocalyx layer on the endothelial cell surface acts as a barrier to maintain endothelial biological function, and it can be impaired by oxidative stress. However, the mechanism of glycocalyx damage during the development of atherosclerosis remains largely unclear. Herein, we established a novel strategy to address these issues from the glycomic perspective that has long been neglected. Using countercharged fluorescence protein staining and quantitative mass spectrometry, we found that heparan sulfate, a major component of the glycocalyx, was structurally altered by oxidative stress. Comparative proteomics and protein microarray analysis revealed several new heparan sulfate-binding proteins, among which alpha-2-Heremans-Schmid glycoprotein (AHSG) was identified as a critical protein. The molecular mechanism of AHSG with heparin was characterized through several methods. A heparan analog could relieve atherosclerosis by protecting heparan sulfate from degradation during oxidative stress and by reducing the accumulation of AHSG at lesion sites. In the present study, the molecular mechanism of anti-atherosclerotic effect of heparin through interaction with AHSG was revealed. These findings provide new insights into understanding of glycocalyx damage in atherosclerosis and lead to the development of corresponding therapeutics.