Spatiotemporal regulation of Rho GTPase signaling during endothelial barrier remodeling

Quantitative proteomic landscape of the pathophysiology of adhesive arachnoiditis and its clinical significance: Structure and mechanism of TNC and RANBP1 proteins

The pathophysiological mechanism of adhesive arachnoiditis (AA) is complex, involving the interaction of multiple proteins. In recent years, the development of quantitative proteomics technology has provided a new perspective to reveal its pathological mechanism. The main objective of this study was to reveal the changes of protein expression profiles in arachnoid tissue of patients with AA. Proteomic analysis of arachnoid tissue samples was performed by high-throughput mass spectrometry. Bioinformatics tools were used to process and analyze the data and screen out 712 differentially expressed proteins (DEPs). Specially, 2 hub DEPs (TNC and RANBP1) were found as potential diagnostic markers. The expression levels of TNC and RANBP1 proteins were significantly up-regulated in patients with AA. TNC protein played a key role in inflammation and extracellular matrix remodeling, while RANBP1 was involved in cytoplasmic transport and cell cycle regulation. The abnormal expression and modification of these two proteins were closely related to the pathophysiological process of the disease. Immunoinfiltration analysis found the pathological process of AA were related to the infiltration of memory B cells, activated NK cells and CD8(+) T cells. Additonally, weighted gene co-expression network analysis (WGCNA) showed the organization of the arachnoid proteome into a network of 28 biologically meaningful modules of co-expressed proteins. Of these, 2 modules were positively correlated to AA phenotypes. This study shows a distinct proteomic landscape of AA and non-adhesive arachnoiditis (nAA). These findings also provide valuable insights into the molecular changes associated with potential mechanisms underlying AA.

Transcriptomic profiling with vascular tension analyses reveals molecular targets and phenotypes in preeclamptic placental vasculature

Introduction

The placental vascular system plays an important role in the development of pregnancy hypertension in preeclampsia. The gene profiles of whole placental tissue (containing blood vessels and many other structural components) and pure vascular tissue should be very different. All previous reports using RNA-seq analysis in the placenta have tested its whole tissue or the villous part, and thus the gene profiles in the pure placental blood vessels are unknown.

Methods

This study was the first to address this point with RNA-seq in human placenta at the transcript level. Isolated placental micro-vessels from normal and preeclamptic pregnancies were used for RNA-seq analysis, real-time quantitative polymerase chain reaction (RT-qPCR) verification, and vascular function tests. Furthermore, a vascular function-centric core network was constructed to show the gene-gene interactions and gene-function associations in the placental vessel system.

Results

Differential expression analysis identified a total of 486 significantly changed transcripts. Bioinformatics analysis further confirmed that multiple genes were highly related to blood vessel and placental phenotypes. Several hub genes, including ELMO1, YWHAE, and IL6ST, were significantly reduced in the placental vessels in preeclampsia. Vascular tension experiments showed that angiotensin II-mediated vasoconstriction and exogenous NO donor sodium nitroprusside-induced vasodilation were decreased, while phenylephrine-mediated vascular responses were unchanged in placental micro-vessels in preeclampsia.

Discussion

The results provide important insights into the pathological process in the placental vasculature in preeclampsia and offer great potential for further investigation of these molecular targets in the human placental vascular system.

A Novel Single-Color FRET Sensor for Rho-Kinase Reveals Calcium-Dependent Activation of RhoA and ROCK

Ras homolog family member A (RhoA) acts as a signaling hub in many cellular processes, including cytoskeletal dynamics, division, migration, and adhesion. RhoA activity is tightly spatiotemporally controlled, but whether downstream effectors share these activation dynamics is unknown. We developed a novel single-color FRET biosensor to measure Rho-associated kinase (ROCK) activity with high spatiotemporal resolution in live cells. We report the validation of the Rho-Kinase Activity Reporter (RhoKAR) biosensor. RhoKAR activation was specific to ROCK activity and was insensitive to PKA activity. We then assessed the mechanisms of ROCK activation in mouse fibroblasts. Increasing intracellular calcium with ionomycin increased RhoKAR activity and depleting intracellular calcium with EGTA decreased RhoKAR activity. We also investigated the signaling intermediates in this process. Blocking calmodulin or CaMKII prevented calcium-dependent activation of ROCK. These results indicate that ROCK activity is increased by calcium in fibroblasts and that this activation occurs downstream of CaM/CaMKII.

Molecular dynamics simulations for the structure-based drug design: targeting small-GTPases proteins

INTRODUCTION

Molecular Dynamics (MD) simulations can support mechanism-based drug design. Indeed, MD simulations by capturing biomolecule motions at finite temperatures can reveal hidden binding sites, accurately predict drug-binding poses, and estimate the thermodynamics and kinetics, crucial information for drug discovery campaigns. Small-Guanosine Triphosphate Phosphohydrolases (GTPases) regulate a cascade of signaling events, that affect most cellular processes. Their deregulation is linked to several diseases, making them appealing drug targets. The broad roles of small-GTPases in cellular processes and the recent approval of a covalent KRas inhibitor as an anticancer agent renewed the interest in targeting small-GTPase with small molecules.

AREA COVERED

This review emphasizes the role of MD simulations in elucidating small-GTPase mechanisms, assessing the impact of cancer-related variants, and discovering novel inhibitors.

EXPERT OPINION

The application of MD simulations to small-GTPases exemplifies the role of MD simulations in the structure-based drug design process for challenging biomolecular targets. Furthermore, AI and machine learning-enhanced MD simulations, coupled with the upcoming power of quantum computing, are promising instruments to target elusive small-GTPases mutations and splice variants. This powerful synergy will aid in developing innovative therapeutic strategies associated to small-GTPases deregulation, which could potentially be used for personalized therapies and in a tissue-agnostic manner to treat tumors with mutations in small-GTPases.

Erk1/2 is not required for endothelial barrier establishment despite its requirement for cAMP-dependent Rac1 activation in heart endothelium

The contribution of Erk1/2 to endothelial barrier regulation is convoluted and differs depending on the vascular bed. We explored the effects of Erk1/2 inhibition on endothelial barrier maintenance and its relationship with cAMP-dependent barrier strengthening. Thus, myocardial endothelial cells (MyEnd) were isolated and protein expression, localization and activity of structural and signaling molecules involved in maintenance of endothelial function were investigated by Western blot, immunostainings and G-LISA, respectively. The transendothelial electrical resistance (TEER) from confluent MyEnd monolayers was measured and used as a direct indicator of barrier integrity in vitro. Miles assay was performed to evaluate vascular permeability in vivo. Erk1/2 inhibition with U0126 affected neither the structural organization of adherens or tight junctions nor the protein level of their components, However, TEER drop significantly upon U0126 application, but the effect was transitory as the barrier function recovered 30 min after treatment. Erk1/2 inhibition delayed cAMP-mediated barrier strengthening but did not prevent barrier fortification despite diminishing Rac1 activation. Moreover, Erk1/2 inhibition, induced vascular leakage that could be prevented by local cAMP elevation in vivo. Our data demonstrate that Erk1/2 is required to prevent vascular permeability but is not critical for cAMP-mediated barrier enhancement.

Exploring the nexus between MYH9 and tumors: novel insights and new therapeutic opportunities

The myosin heavy chain 9 (MYH9) gene, located on human chromosome 22, encodes non-muscle myosin heavy chain IIA (NM IIA). This protein is essential to various cellular events, such as generating intracellular chemomechanical force and facilitating the movement of the actin cytoskeleton. Mutations associated with thrombocytopenia in autosomal dominant diseases first highlighted the significance of the MYH9 gene. In recent years, numerous studies have demonstrated the pivotal roles of MYH9 in various cancers. However, its effects on cancer are intricate and not fully comprehended. Furthermore, the elevated expression of MYH9 in certain malignancies suggests its potential as a target for tumor therapy. Nonetheless, there is a paucity of literature summarizing MYH9's role in tumors and the therapeutic strategies centered on it, necessitating a systematic analysis. This paper comprehensively reviews and analyzes the pertinent literature in this domain, elucidating the fundamental structural characteristics, biological functions, and the nexus between MYH9 and tumors. The mechanisms through which MYH9 contributes to tumor development and its multifaceted roles in the tumorigenic process are also explored. Additionally, we discuss the relationship between MYH9-related diseases (MYH9-RD) and tumors and also summarize tumor therapeutic approaches targeting MYH9. The potential clinical applications of studying the MYH9 gene include improving early diagnosis, clinical staging, and prognosis of tumors. This paper is anticipated to provide novel insights for tumor therapy.

The Vitamin K-Dependent Anticoagulant Factor, Protein S, Regulates Vascular Permeability

Protein S (PROS1) is a vitamin K-dependent anticoagulant factor, which also acts as an agonist for the TYRO3, AXL, and MERTK (TAM) tyrosine kinase receptors. PROS1 is produced by the endothelium which also expresses TAM receptors, but little is known about its effects on vascular function and permeability. Transwell permeability assays as well as Western blotting and immunostaining analysis were used to monitor the possible effects of PROS1 on both endothelial cell permeability and on the phosphorylation state of specific signaling proteins. We show that human PROS1, at its circulating concentrations, substantially increases both the basal and VEGFA-induced permeability of endothelial cell (EC) monolayers. PROS1 induces p38 MAPK (Mitogen Activated Protein Kinase), Rho/ROCK (Rho-associated protein kinase) pathway activation, and actin filament remodeling, as well as substantial changes in Vascular Endothelial Cadherin (VEC) distribution and its phosphorylation on Ser665 and Tyr685. It also mediates c-Src and PAK-1 (p21-activated kinase 1) phosphorylation on Tyr416 and Ser144, respectively. Exposure of EC to human PROS1 induces VEC internalization as well as its cleavage into a released fragment of 100 kDa and an intracellular fragment of 35 kDa. Using anti-TAM neutralizing antibodies, we demonstrate that PROS1-induced VEC and c-Src phosphorylation are mediated by both the MERTK and TYRO3 receptors but do not involve the AXL receptor. MERTK and TYRO3 receptors are also responsible for mediating PROS1-induced MLC (Myosin Light Chain) phosphorylation on a site targeted by the Rho/ROCK pathway. Our report provides evidence for the activation of the c-Src/VEC and Rho/ROCK/MLC pathways by PROS1 for the first time and points to a new role for PROS1 as an endogenous vascular permeabilizing factor.