Adhesion signaling - crosstalk between integrins, Src and Rho

Kinesin-1 mediates proper ER folding of the CaV1.2 channel and maintains mouse glucose homeostasis

Glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells is a principal mechanism for systemic glucose homeostasis, of which regulatory mechanisms are still unclear. Here we show that kinesin molecular motor KIF5B is essential for GSIS through maintaining the voltage-gated calcium channel CaV1.2 levels, by facilitating an Hsp70-to-Hsp90 chaperone exchange to pass through the quality control in the endoplasmic reticulum (ER). Phenotypic analyses of KIF5B conditional knockout (cKO) mouse beta cells revealed significant abolishment of glucose-stimulated calcium transients, which altered the behaviors of insulin granules via abnormally stabilized cortical F-actin. KIF5B and Hsp90 colocalize to microdroplets on ER sheets, where CaV1.2 but not Kir6.2 is accumulated. In the absence of KIF5B, CaV1.2 fails to be transferred from Hsp70 to Hsp90 via STIP1, and is likely degraded via the proteasomal pathway. KIF5B and Hsc70 overexpression increased CaV1.2 expression via enhancing its chaperone binding. Thus, ER sheets may serve as the place of KIF5B- and Hsp90-dependent chaperone exchange, which predominantly facilitates CaV1.2 production in beta cells and properly enterprises GSIS against diabetes.

WISP1 and Macrophage Migration Inhibitory Factor in Respiratory Inflammation: Novel Insights and Therapeutic Potentials for Asthma and COPD

Recent advancements highlight the intricate interplay between the extracellular matrix (ECM) and immune responses, notably in respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD). The ECM, a dynamic structural framework within tissues, orches-trates a plethora of cellular processes, including immune cell behavior and tissue repair mecha-nisms. WNT1-inducible-signaling pathway protein 1 (WISP1), a key ECM regulator, controls immune cell behavior, cytokine production, and tissue repair by modulating integrins, PI3K, Akt, β-catenin, and mTOR signaling pathways. WISP1 also induces macrophage migration inhibitory factor (MIF) expression via Src kinases and epidermal growth factor receptor (EGFR) activation. MIF, through its wide range of activities, enhances inflammation and tissue restructuring. Rec-ognized for its versatile roles in regulating the immune system, MIF interacts with multiple immune components, such as the NLRP3 inflammasome, thereby sustaining inflammatory pro-cesses. The WISP1-MIF axis potentially unveils complex molecular mechanisms governing im-mune responses and inflammation. Understanding the intricate roles of WISP1 and MIF in the pathogenesis of chronic respiratory diseases such as asthma and COPD could lead to the identi-fication of novel targets for therapeutic intervention to alleviate disease severity and enhance patient outcomes.

Exogenous S1P via S1P receptor 2 induces CTGF expression through Src-RhoA-ROCK-YAP pathway in hepatic stellate cells

BACKGROUND

Hepatic fibrosis, a prevalent chronic liver condition, involves excessive extracellular matrix production associated with aberrant wound healing. Hepatic stellate cells (HSCs) play a pivotal role in liver fibrosis, activated by inflammatory factors such as sphingosine 1-phosphate (S1P). Despite S1P's involvement in fibrosis, its specific role and downstream pathway in HSCs remain controversial.

METHODS

In this study, we investigated the regulatory role of S1P/S1P receptor (S1PR) in Hippo-YAP activation in both LX-2 cell lines and primary HSCs. Real-time PCR, western blot, pharmacological inhibitors, siRNAs, and Rho activity assays were adopted to address the molecular mechanisms of S1P mediated YAP activation.

RESULTS

Serum and exogenous S1P significantly increased the expression of YAP target genes in HSCs. Pharmacologic inhibitors and siRNA-mediated knockdowns of S1P receptors showed S1P receptor 2 (S1PR2) as the primary mediator for S1P-induced CTGF expression in HSCs. Results using siRNA-mediated knockdown, Verteporfin, and Phospho-Tag immunoblots showed that S1P-S1PR2 signaling effectively suppressed the Hippo kinases cascade, thereby activating YAP. Furthermore, S1P increased RhoA activities in cells and ROCK inhibitors effectively blocked CTGF induction. Cytoskeletal-perturbing reagents were shown to greatly modulate CTGF induction, suggesting the important role of actin cytoskeleton in S1P-induced YAP activation. Exogeneous S1P treatment was enough to increase the expression of COL1A1 and α-SMA, that were blocked by YAP specific inhibitor.

CONCLUSIONS

Our data demonstrate that S1P/S1PR2-Src-RhoA-ROCK axis leads to Hippo-YAP activation, resulting in the up-regulation of CTGF, COL1A1 and α-SMA expression in HSCs. Therefore, S1PR2 may represent a potential therapeutic target for hepatic fibrosis.

Development of advanced cardiac progenitor cell culture system through fibronectin and vitronectin derived peptide coated plate

Cardiovascular disease remains a global health concern. Stem cell therapy utilizing human cardiac progenitor cells (hCPCs) shows promise in treating cardiac vascular disease. However, limited availability and senescence of hCPCs hinder their widespread use. To address these challenges, researchers are exploring innovative approaches. In this study, a bioengineered cell culture plate was developed to mimic the natural cardiac tissue microenvironment. It was coated with a combination of extracellular matrix (ECM) peptide motifs and mussel adhesive protein (MAP). The selected ECM peptide motifs, derived from fibronectin and vitronectin, play crucial roles in hCPCs. Results revealed that the Fibro-P and Vitro-P coated plates significantly improved hCPC adhesion, proliferation, migration, and differentiation compared to uncoated plates. Additionally, long-term culture on the coated plates delayed cellular senescence and maintained hCPC stemness. These enhancements were attributed to the activation of integrin downstream signaling pathways. The findings suggest that the engineered ECM peptide motif-MAP-coated plates hold potential for enhancing the therapeutic efficacy of stem cell-based therapies in cardiac tissue engineering and regenerative medicine.

Focal adhesion kinase regulates tendon cell mechanoresponse and physiological tendon development

Tendons enable locomotion by transmitting high tensile mechanical forces between muscle and bone via their dense extracellular matrix (ECM). The application of extrinsic mechanical stimuli via muscle contraction is necessary to regulate healthy tendon function. Specifically, applied physiological levels of mechanical loading elicit an anabolic tendon cell response, while decreased mechanical loading evokes a degradative tendon state. Although the tendon response to mechanical stimuli has implications in disease pathogenesis and clinical treatment strategies, the cell signaling mechanisms by which tendon cells sense and respond to mechanical stimuli within the native tendon ECM remain largely unknown. Therefore, we explored the role of cell-ECM adhesions in regulating tendon cell mechanotransduction by perturbing the genetic expression and signaling activity of focal adhesion kinase (FAK) through both in vitro and in vivo approaches. We determined that FAK regulates tendon cell spreading behavior and focal adhesion morphology, nuclear deformation in response to applied mechanical strain, and mechanosensitive gene expression. In addition, our data reveal that FAK signaling plays an essential role in in vivo tendon development and postnatal growth, as FAK-knockout mouse tendons demonstrated reduced tendon size, altered mechanical properties, differences in cellular composition, and reduced maturity of the deposited ECM. These data provide a foundational understanding of the role of FAK signaling as a critical regulator of in situ tendon cell mechanotransduction. Importantly, an increased understanding of tendon cell mechanotransductive mechanisms may inform clinical practice as well as lead to the discovery of diagnostic and/or therapeutic molecular targets.

I told you to stop: obscurin's role in epithelial cell migration

The giant cytoskeletal protein obscurin contains multiple cell signaling domains that influence cell migration. Here, we follow each of these pathways, examine how these pathways modulate epithelial cell migration, and discuss the cross-talk between these pathways. Specifically, obscurin uses its PH domain to inhibit phosphoinositide-3-kinase (PI3K)-dependent migration and its RhoGEF domain to activate RhoA and slow cell migration. While obscurin's effect on the PI3K pathway agrees with the literature, obscurin's effect on the RhoA pathway runs counter to most other RhoA effectors, whose activation tends to lead to enhanced motility. Obscurin also phosphorylates cadherins, and this may also influence cell motility. When taken together, obscurin's ability to modulate three independent cell migration pathways is likely why obscurin knockout cells experience enhanced epithelial to mesenchymal transition, and why obscurin is a frequently mutated gene in several types of cancer.

Non-Receptor Tyrosine Kinases: Their Structure and Mechanistic Role in Tumor Progression and Resistance

Protein tyrosine kinases (PTKs) function as key molecules in the signaling pathways in addition to their impact as a therapeutic target for the treatment of many human diseases, including cancer. PTKs are characterized by their ability to phosphorylate serine, threonine, or tyrosine residues and can thereby rapidly and reversibly alter the function of their protein substrates in the form of significant changes in protein confirmation and affinity for their interaction with protein partners to drive cellular functions under normal and pathological conditions. PTKs are classified into two groups: one of which represents tyrosine kinases, while the other one includes the members of the serine/threonine kinases. The group of tyrosine kinases is subdivided into subgroups: one of them includes the member of receptor tyrosine kinases (RTKs), while the other subgroup includes the member of non-receptor tyrosine kinases (NRTKs). Both these kinase groups function as an "on" or "off" switch in many cellular functions. NRTKs are enzymes which are overexpressed and activated in many cancer types and regulate variable cellular functions in response to extracellular signaling-dependent mechanisms. NRTK-mediated different cellular functions are regulated by kinase-dependent and kinase-independent mechanisms either in the cytoplasm or in the nucleus. Thus, targeting NRTKs is of great interest to improve the treatment strategy of different tumor types. This review deals with the structure and mechanistic role of NRTKs in tumor progression and resistance and their importance as therapeutic targets in tumor therapy.

Cytotoxicity and toxicoproteomics analysis of thiazolidinedione exposure in human-derived cardiomyocytes

Thiazolidinediones (TZDs) (e.g. pioglitazone and rosiglitazone), known insulin sensitiser agents for type II diabetes mellitus, exhibit controversial effects on cardiac tissue. Despite consensus on their association with increased heart failure risk, limiting TZD use in diabetes management, the underlying mechanisms remain uncharacterised. Herein, we report a comprehensive in vitro investigation utilising a novel toxicoproteomics pipeline coupled with cytotoxicity assays in human adult cardiomyocytes to elucidate mechanistic insights into TZD cardiotoxicity. The cytotoxicity assay findings showed a significant loss of mitochondrial adenosine triphosphate production upon exposure to either TZD agents, which may underpin TZD cardiotoxicity. Our toxicoproteomics analysis revealed that mitochondrial dysfunction primarily stems from oxidative phosphorylation impairment, with distinct signalling mechanisms observed for both agents. The type of cell death differed strikingly between the two agents, with rosiglitazone exhibiting features of caspase-dependent apoptosis and pioglitazone implicating mitochondrial-mediated necroptosis, as evidenced by the protein upregulation in the phosphoglycerate mutase family 5-dynamin-related protein 1 axis. Furthermore, our analysis revealed additional mechanistic aspects of cardiotoxicity, showcasing drug specificity. The downregulation of various proteins involved in protein machinery and protein processing in the endoplasmic reticulum was observed in rosiglitazone-treated cells, implicating proteostasis in the rosiglitazone cardiotoxicity. Regarding pioglitazone, the findings suggested the potential activation of the interplay between the complement and coagulation systems and the disruption of the cytoskeletal architecture, which was primarily mediated through the integrin-signalling pathways responsible for pioglitazone-induced myocardial contractile failure. Collectively, this study unlocks substantial mechanistic insight into TZD cardiotoxicity, providing the rationale for future optimisation of antidiabetic therapies.

Emerging roles of deubiquitinating enzymes in actin cytoskeleton and tumor metastasis

BACKGROUND

Metastasis accounts for the majority of cancer-related deaths. Actin dynamics and actin-based cell migration and invasion are important factors in cancer metastasis. Metastasis is characterized by actin polymerization and depolymerization, which are precisely regulated by molecular changes involving a plethora of actin regulators, including actin-binding proteins (ABPs) and signalling pathways, that enable cancer cell dissemination from the primary tumour. Research on deubiquitinating enzymes (DUBs) has revealed their vital roles in actin dynamics and actin-based migration and invasion during cancer metastasis.

CONCLUSION

Here, we review how DUBs drive tumour metastasis by participating in actin rearrangement and actin-based migration and invasion. We summarize the well-characterized and essential actin cytoskeleton signalling molecules related to DUBs, including Rho GTPases, Src kinases, and ABPs such as cofilin and cortactin. Other DUBs that modulate actin-based migration signalling pathways are also discussed. Finally, we discuss and address therapeutic opportunities and ongoing challenges related to DUBs with respect to actin dynamics.

Effects of Angiogenic Factors on the Epithelial-to-Mesenchymal Transition and Their Impact on the Onset and Progression of Oral Squamous Cell Carcinoma: An Overview

High levels of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF)-2 and angiopoietin (ANG)-2 are found in tissues from oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMDs). As might be expected, VEGF, FGF-2, and ANG-2 overexpression parallels the development of new blood and lymphatic vessels that nourish the growing OPMDs or OSCCs and provide the latter with metastatic routes. Notably, VEGF, FGF-2, and ANG-2 are also linked to the epithelial-to-mesenchymal transition (EMT), a trans-differentiation process that respectively promotes or exasperates the invasiveness of normal and neoplastic oral epithelial cells. Here, we have summarized published work regarding the impact that the interplay among VEGF, FGF-2, ANG-2, vessel generation, and EMT has on oral carcinogenesis. Results from the reviewed studies indicate that VEGF, FGF-2, and ANG-2 spark either protein kinase B (AKT) or mitogen-activated protein kinases (MAPK), two signaling pathways that can promote both EMT and new vessels' formation in OPMDs and OSCCs. Since EMT and vessel generation are key to the onset and progression of OSCC, as well as to its radio- and chemo-resistance, these data encourage including AKT or MAPK inhibitors and/or antiangiogenic drugs in the treatment of this malignancy.

The involvement of interferon regulatory factor 8 in regulating the proliferation of haemocytes in oyster Crassostrea gigas

Interferon regulatory factor 8 (IRF8) is an important transcriptional regulatory factor involving in multiple biological process, such as the antiviral immune response, immune cell proliferation and differentiation. In the present study, the involvement of a previously identified IRF8 homologue (CgIRF8) in regulating haemocyte proliferation of oyster were further investigated. CgIRF8 mRNA transcripts were detectable in all the stages of C. gigas larvae with the highest level in D-veliger (1.76-fold of that in zygote, p < 0.05). Its mRNA transcripts were also detected in all the three haemocyte subpopulations of adult oysters with the highest expression in granulocytes (2.79-fold of that in agranulocytes, p < 0.01). After LPS stimulation, the mRNA transcripts of CgIRF8 in haemocytes significantly increased at 12 h and 48 h, which were 2.04-fold and 1.65-fold (p < 0.05) of that in control group, respectively. Meanwhile, the abundance of CgIRF8 protein in the haemocytes increased significantly at 12 h after LPS stimulation (1.71-fold of that in seawater, p < 0.05). The immunofluorescence assay and Western blot showed that LPS stimulation induced an obvious nucleus translocation of CgIRF8 protein in haemocytes. After the expression of CgIRF8 was inhibited by the injection of CgIRF8 siRNA, the percentage of EdU positive haemocytes, the proportion of granulocytes, and the mRNA expression levels of CgGATA and CgSCL all declined significantly at 12 h after LPS stimulation, which was 0.64-fold (p < 0.05), 0.7-fold (p < 0.05), 0.31-fold and 0.54-fold (p < 0.001) of that in the NC group, respectively. While the expression level of cell proliferation-related protein CgCDK2, CgCDC6, CgCDC45 and CgPCNA were significantly increased (1.99-fold, and 2.41-fold, 3.76-fold and 4.79-fold compared to that in the NC group respectively, p < 0.001). Dual luciferase reporter assay demonstrated that CgIRF8 was able to activate the CgGATA promoter in HEK293T cells after transfection of CgGATA and CgIRF8. These results collectively indicated that CgIRF8 promoted haemocyte proliferation by regulating the expression of CgGATA and other related genes in the immune response of oyster.

Decoding dysregulated genes, molecular pathways and microRNAs involved in cervical cancer

BACKGROUND

The present study aimed to identify dysregulated genes, molecular pathways, and regulatory mechanisms in human papillomavirus (HPV)-associated cervical cancers. We have investigated the disease-associated genes along with the Gene Ontology, survival prognosis, transcription factors and the microRNA (miRNA) that are involved in cervical carcinogenesis, enabling a deeper comprehension of cervical cancer linked to HPV.

METHODS

We used 10 publicly accessible Gene Expression Omnibus (GEO) datasets to examine the patterns of gene expression in cervical cancer. Differentially expressed genes (DEGs), which showed a clear distinction between cervical cancer and healthy tissue samples, were analyzed using the GEO2R tool. Additional bioinformatic techniques were used to carry out pathway analysis and functional enrichment, as well as to analyze the connection between altered gene expression and HPV infection.

RESULTS

In total, 48 DEGs were identified to be differentially expressed in cervical cancer tissues in comparison to healthy tissues. Among DEGs, CCND1, CCNA2 and SPP1 were the key dysregulated genes involved in HPV-associated cervical cancer. The five common miRNAs that were identified against these genes are miR-7-5p, miR-16-5p, miR-124-3p, miR-10b-5p and miR-27a-3p. The hub-DEGs targeted by miRNA hsa-miR-27a-3p are controlled by the common transcription factor SP1.

CONCLUSIONS

The present study has identified DEGs involved in HPV-associated cervical cancer progression and the various molecular pathways and transcription factors regulating them. These findings have led to a better understanding of cervical cancer resulting in the development and identification of possible therapeutic and intervention targets, respectively.

Mechanotransduction in stem cells

Nowadays, it is an established concept that the capability to reach a specialised cell identity via differentiation, as in the case of multi- and pluripotent stem cells, is not only determined by biochemical factors, but that also physical aspects of the microenvironment play a key role; interpreted by the cell through a force-based signalling pathway called mechanotransduction. However, the intricate ties between the elements involved in mechanotransduction, such as the extracellular matrix, the glycocalyx, the cell membrane, Integrin adhesion complexes, Cadherin-mediated cell/cell adhesion, the cytoskeleton, and the nucleus, are still far from being understood in detail. Here we report what is currently known about these elements in general and their specific interplay in the context of multi- and pluripotent stem cells. We furthermore merge this overview to a more comprehensive picture, that aims to cover the whole mechanotransductive pathway from the cell/microenvironment interface to the regulation of the chromatin structure in the nucleus. Ultimately, with this review we outline the current picture of the interplay between mechanotransductive cues and epigenetic regulation and how these processes might contribute to stem cell dynamics and fate.

Extracellular matrix stiffness mediates insulin secretion in pancreatic islets via mechanosensitive Piezo1 channel regulated Ca2+ dynamics

The pancreatic islet is surrounded by ECM that provides both biochemical and mechanical cues to the islet β-cell to regulate cell survival and insulin secretion. Changes in ECM composition and mechanical properties drive β-cell dysfunction in many pancreatic diseases. While several studies have characterized changes in islet insulin secretion with changes in substrate stiffness, little is known about the mechanotransduction signaling driving altered islet function in response to mechanical cues. We hypothesized that increasing matrix stiffness will lead to insulin secretion dysfunction by opening the mechanosensitive ion channel Piezo1 and disrupting intracellular Ca2+ dynamics in mouse and human islets. To test our hypothesis, mouse and human cadaveric islets were encapsulated in a biomimetic reverse thermal gel (RTG) scaffold with tailorable stiffness that allows formation of islet focal adhesions with the scaffold and activation of Piezo1 in 3D. Our results indicate that increased scaffold stiffness causes insulin secretion dysfunction mediated by increases in Ca2+ influx and altered Ca2+ dynamics via opening of the mechanosensitive Piezo1 channel. Additionally, inhibition of Piezo1 rescued glucose-stimulated insulin secretion (GSIS) in islets in stiff scaffolds. Overall, our results emphasize the role mechanical properties of the islet microenvironment plays in regulating function. It also supports further investigation into the modulation of Piezo1 channel activity to restore islet function in diseases like type 2 diabetes (T2D) and pancreatic cancer where fibrosis of the peri-islet ECM leads to increased tissue stiffness and islet dysfunction.

The epithelial adherens junction component PLEKHA7 regulates ECM remodeling and cell behavior through miRNA-mediated regulation of MMP1 and LOX

Epithelial adherens junctions (AJs) are cell-cell adhesion complexes that are influenced by tissue mechanics, such as those emanating from the extracellular matrix (ECM). Here, we introduce a mechanism whereby epithelial AJs can also regulate the ECM. We show that the AJ component PLEKHA7 regulates levels and activity of the key ECM remodeling components MMP1 and LOX in well-differentiated colon epithelial cells, through the miR-24 and miR-30c miRNAs. PLEKHA7 depletion in epithelial cells results in LOX-dependent ECM remodeling in culture and in the colonic mucosal lamina propria in mice. Furthermore, PLEKHA7-depleted cells exhibit increased migration and invasion rates that are MMP1- and LOX- dependent, and form colonies in 3D cultures that are larger in size and acquire aberrant morphologies in stiffer matrices. These results reveal an AJ-mediated mechanism, through which epithelial cells drive ECM remodeling to modulate their behavior, including acquisition of phenotypes that are hallmarks of conditions such as fibrosis and tumorigenesis.

Vesicle fusion and release in neurons under dynamic mechanical equilibrium

Vesicular fusion plays a pivotal role in cellular processes, involving stages like vesicle trafficking, fusion pore formation, content release, and membrane integration or separation. This dynamic process is regulated by a complex interplay of protein assemblies, osmotic forces, and membrane tension, which together maintain a mechanical equilibrium within the cell. Changes in cellular mechanics or external pressures prompt adjustments in this equilibrium, highlighting the system's adaptability. This review delves into the synergy between intracellular proteins, structural components, and external forces in facilitating vesicular fusion and release. It also explores how cells respond to mechanical stress, maintaining equilibrium and offering insights into vesicle fusion mechanisms and the development of neurological disorders.

Differential Smad2/3 linker phosphorylation is a crosstalk mechanism of Rho/ROCK and canonical TGF-β3 signaling in tenogenic differentiation

The transforming growth factor (TGF)-β3 is a well-known inducer for tenogenic differentiation, signaling via the Smad2/3 pathway. Furthermore, other factors like extracellular matrix or mechanical force can induce tenogenic differentiation and possibly alter the response to TGF-β3 by signaling via the Rho/ROCK pathway. The aim of this study was to investigate the interplay of Rho/ROCK and TGF-β3/Smad signaling in tenogenic differentiation, with the Smad2/3 molecule hypothesized as a possible interface. Cultured as monolayers or on collagen I matrices, mesenchymal stromal cells (MSC) were treated with the ROCK inhibitor Y-27632 (10 µM), TGF-β3 (10 ng/ml) or both combined. Control cells were cultured accordingly, without Y-27632 and/or without TGF-β3. At different time points, MSC were analyzed by real-time RT-PCR, immunofluorescence, and Western blot. Cultivation of MSC on collagen matrices and ROCK inhibition supported tenogenic differentiation and fostered the effect of TGF-β3. The phosphorylation of the linker region of Smad2 was reduced by cultivation on collagen matrices, but not by ROCK inhibition. The latter, however, led to increased phosphorylation of the linker region of Smad3. In conclusion, collagen matrices and the Rho/ROCK signaling pathway influence the TGF-β3/Smad2/3 pathway by regulating different phosphorylation sites of the Smad linker region.

Iron/ROS/Itga3 mediated accelerated depletion of hippocampal neural stem cell pool contributes to cognitive impairment after hemorrhagic stroke

Hemorrhagic stroke, specifically intracerebral hemorrhage (ICH), has been implicated in the development of persistent cognitive impairment, significantly compromising the quality of life for affected individuals. Nevertheless, the precise underlying mechanism remains elusive. Here, we report for the first time that the accumulation of iron within the hippocampus, distal to the site of ICH in the striatum, is causally linked to the observed cognitive impairment with both clinical patient data and animal model. Both susceptibility-weighted imaging (SWI) and quantitative susceptibility mapping (QSM) demonstrated significant iron accumulation in the hippocampus of ICH patients, which is far from the actual hematoma. Logistical regression analysis and multiple linear regression analysis identified iron level as an independent risk factor with a negative correlation with post-ICH cognitive impairment. Using a mouse model of ICH, we demonstrated that iron accumulation triggers an excessive activation of neural stem cells (NSCs). This overactivation subsequently leads to the depletion of the NSC pool, diminished neurogenesis, and the onset of progressive cognitive dysfunction. Mechanistically, iron accumulation elevated the levels of reactive oxygen species (ROS), which downregulated the expression of Itga3. Notably, pharmacological chelation of iron accumulation or scavenger of aberrant ROS levels, as well as conditionally overexpressed Itga3 in NSCs, remarkably attenuated the exhaustion of NSC pool, abnormal neurogenesis and cognitive decline in the mouse model of ICH. Together, these results provide molecular insights into ICH-induced cognitive impairment, shedding light on the value of maintaining NSC pool in preventing cognitive dysfunction in patients with hemorrhagic stroke or related conditions.

Inhibiting MMP13 Attenuates Deep Vein Thrombosis in a Mouse Model by Reducing the Expression of Pdpn

OBJECTIVE

Matrix metalloproteinase 13 (MMP13) is an extracellular matrix protease that affects the progression of atherosclerotic plaques and arterial thrombi by degrading collagens, modifying protein structures and regulating inflammatory responses, but its role in deep vein thrombosis (DVT) has not been determined. The purpose of this study was to investigate the potential effects of MMP13 and MMP13-related genes on the formation of DVT.

METHODS

We altered the expression level of MMP13 in vivo and conducted a transcriptome study to examine the expression and relationship between MMP13 and MMP13-related genes in a mouse model of DVT. After screening genes possibly related to MMP13 in DVT mice, the expression levels of candidate genes in human umbilical vein endothelial cells (HUVECs) and the venous wall were evaluated. The effect of MMP13 on platelet aggregation in HUVECs was investigated in vitro.

RESULTS

Among the differentially expressed genes, interleukin 1 beta, podoplanin (Pdpn), and factor VIII von Willebrand factor (F8VWF) were selected for analysis in mice. When MMP13 was inhibited, the expression level of PDPN decreased significantly in vitro. In HUVECs, overexpression of MMP13 led to an increase in the expression level of PDPN and induced platelet aggregation, while transfection of PDPN-siRNA weakened the ability of MMP13 to increase platelet aggregation.

CONCLUSIONS

Inhibiting the expression of MMP13 could reduce the burden of DVT in mice. The mechanism involves downregulating the expression of Pdpn through MMP13, which could provide a novel gene target for DVT diagnosis and treatment.

Newcastle disease virus activates diverse signaling pathways via Src to facilitate virus entry into host macrophages

As an intrinsic cellular mechanism responsible for the internalization of extracellular ligands and membrane components, caveolae-mediated endocytosis (CavME) is also exploited by certain pathogens for endocytic entry [e.g., Newcastle disease virus (NDV) of paramyxovirus]. However, the molecular mechanisms of NDV-induced CavME remain poorly understood. Herein, we demonstrate that sialic acid-containing gangliosides, rather than glycoproteins, were utilized by NDV as receptors to initiate the endocytic entry of NDV into HD11 cells. The binding of NDV to gangliosides induced the activation of a non-receptor tyrosine kinase, Src, leading to the phosphorylation of caveolin-1 (Cav1) and dynamin-2 (Dyn2), which contributed to the endocytic entry of NDV. Moreover, an inoculation of cells with NDV-induced actin cytoskeletal rearrangement through Src to facilitate NDV entry via endocytosis and direct fusion with the plasma membrane. Subsequently, unique members of the Rho GTPases family, RhoA and Cdc42, were activated by NDV in a Src-dependent manner. Further analyses revealed that RhoA and Cdc42 regulated the activities of specific effectors, cofilin and myosin regulatory light chain 2, responsible for actin cytoskeleton rearrangement, through diverse intracellular signaling cascades. Taken together, our results suggest that an inoculation of NDV-induced Src-mediated cellular activation by binding to ganglioside receptors. This process orchestrated NDV endocytic entry by modulating the activities of caveolae-associated Cav1 and Dyn2, as well as specific Rho GTPases and downstream effectors.

IMPORTANCE

In general, it is known that the paramyxovirus gains access to host cells through direct penetration at the plasma membrane; however, emerging evidence suggests more complex entry mechanisms for paramyxoviruses. The endocytic entry of Newcastle disease virus (NDV), a representative member of the paramyxovirus family, into multiple types of cells has been recently reported. Herein, we demonstrate the binding of NDV to induce ganglioside-activated Src signaling, which is responsible for the endocytic entry of NDV through caveolae-mediated endocytosis. This process involved Src-dependent activation of the caveolae-associated Cav1 and Dyn2, as well as specific Rho GTPase and downstream effectors, thereby orchestrating the endocytic entry process of NDV. Our findings uncover a novel molecular mechanism of endocytic entry of NDV into host cells and provide novel insight into paramyxovirus mechanisms of entry.

Effect of Focal Adhesion Kinase and Vinculin Expression on Migration Parameters of Normal and Tumor Epitheliocytes

Focal adhesions (FAs) are mechanosensory structures that transform physical stimuli into chemical signals guiding cell migration. Comprehensive studies postulate correlation between the FA parameters and cell motility metrics for individual migrating cells. However, which properties of the FAs are critical for epithelial cell motility in a monolayer remains poorly elucidated. We used high-throughput microscopy to describe relationship between the FA parameters and cell migration in immortalized epithelial keratinocytes (HaCaT) and lung carcinoma cells (A549) with depleted or inhibited vinculin and focal adhesion kinase (FAK) FA proteins. To evaluate relationship between the FA morphology and cell migration, we used substrates with varying stiffness in the model of wound healing. Cells cultivated on fibronectin had the highest FA area values, migration rate, and upregulated expression of FAK and vinculin mRNAs, while the smallest FA area and slower migration rate to the wound were specific to cells cultivated on glass. Suppression of vinculin expression in both normal and tumor cells caused decrease of the FA size and fluorescence intensity but did not affect cell migration into the wound. In contrast, downregulation or inactivation of FAK did not affect the FA size but significantly slowed down the wound closure rate by both HaCaT and A549 cell lines. We also showed that the FAK knockdown results in the FA lifetime decrease for the cells cultivated both on glass and fibronectin. Our data indicate that the FA lifetime is the most important parameter defining migration of epithelial cells in a monolayer. The observed change in the cell migration rate in a monolayer caused by changes in expression/activation of FAK kinase makes FAK a promising target for anticancer therapy of lung carcinoma.

Loss of Myo19 increases metastasis by enhancing microenvironmental ROS gradient and chemotaxis

Tumor metastasis involves cells migrating directionally in response to external chemical signals. Reactive oxygen species (ROS) in the form of H2O2 has been demonstrated as a chemoattractant for neutrophils but its spatial characteristics in tumor microenvironment and potential role in tumor cell dissemination remain unknown. Here we investigate the spatial ROS distribution in 3D tumor spheroids and identify a ROS concentration gradient in spheroid periphery, which projects into a H2O2 gradient in tumor microenvironment. We further reveal the role of H2O2 gradient to induce chemotaxis of tumor cells by activating Src and subsequently inhibiting RhoA. Finally, we observe that the absence of mitochondria cristae remodeling proteins including the mitochondria-localized actin motor Myosin 19 (Myo19) enhances ROS gradient and promotes tumor dissemination. Myo19 downregulation is seen in many tumors, and Myo19 expression is negatively associated with tumor metastasis in vivo. Together, our study reveals the chemoattractant role of tumor microenvironmental ROS and implies the potential impact of mitochondria cristae disorganization on tumor invasion and metastasis.

Tm4sf19 deficiency inhibits osteoclast multinucleation and prevents bone loss

BACKGROUND

Multinucleation is a hallmark of osteoclast formation and has a unique ability to resorb bone matrix. During osteoclast differentiation, the cytoskeleton reorganization results in the generation of actin belts and eventual bone resorption. Tetraspanins are involved in adhesion, migration and fusion in various cells. However, its function in osteoclast is still unclear. In this study, we identified Tm4sf19, a member of the tetraspanin family, as a regulator of osteoclast function.

MATERIALS AND METHODS

We investigate the effect of Tm4sf19 deficiency on osteoclast differentiation using bone marrow-derived macrophages obtained from wild type (WT), Tm4sf19 knockout (KO) and Tm4sf19 LELΔ mice lacking the large extracellular loop (LEL). We analyzed bone mass of young and aged WT, KO and LELΔ mice by μCT analysis. The effects of Tm4sf19 LEL-Fc fusion protein were accessed in osteoclast differentiation and osteoporosis animal model.

RESULTS

We found that deficiency of Tm4sf19 inhibited osteoclast function and LEL of Tm4sf19 was responsible for its function in osteoclasts in vitro. KO and LELΔ mice exhibited higher trabecular bone mass compared to WT mice. We found that Tm4sf19 interacts with integrin αvβ3 through LEL, and that this binding is important for cytoskeletal rearrangements in osteoclast by regulating signaling downstream of integrin αvβ3. Treatment with LEL-Fc fusion protein inhibited osteoclast function in vitro and administration of LEL-Fc prevented bone loss in an osteoporosis mouse model in vivo.

CONCLUSION

We suggest that Tm4sf19 regulates osteoclast function and that LEL-Fc may be a promising drug to target bone destructive diseases caused by osteoclast hyper-differentiation.

Anoikis and cancer cell differentiation: novel modes of shikonin derivatives anticancer action in vitro

BACKGROUND

Shikonin is a naturally occurring naphthoquinone found in the roots of several genera of the Boraginaceae family, widely known for its numerous biological activities, such as antiinflammatory, antioxidant, antimicrobial and anticancer. In this study, the antitumor effect of six naphthoquinones isolated from the roots of Onosma visianii was evaluated using two cell lines, mouse melanoma B16 and highly aggressive rat glioma cell line C6.

METHODS AND RESULTS

All examined shikonins dose-dependently decreased the viability of tested cells, with compounds 5 and 6 being the most potent ones and hence subjected to further analysis. The diminished viability of B16 melanoma cells was in correlation with detected caspase-mediated apoptosis. Importantly, observed altered cell morphology along with the loss of dividing potential upon exposure to both shikonins implied reprogram of B16 cell phenotype. Elevated expression of myelin basic protein indicated the acquirement of Schwann-like cell phenotype, while detected autophagy might be connected to this phenomenon. On the contrary, upon exposure to both agents, C6 cells underwent specific cell death-anoikis, provoked by detachment from the extracellular matrix and compromised integrin signaling. Oppositely to compound 5, compound 6 realized anoikis in a caspase-independent manner and under sustained ERK1/2 activation, indicating the deviation from standard proanoikis signaling.

CONCLUSIONS

Herein, we have pointed out the diversity and novelty in the mode of action of shikonin derivatives depending on the tumor cell features, which represents a good platform for new investigations of these promising natural compounds.

Portal hypertension in patients with nonalcoholic fatty liver disease: Current knowledge and challenges

Portal hypertension (PH) has traditionally been observed as a consequence of significant fibrosis and cirrhosis in advanced non-alcoholic fatty liver disease (NAFLD). However, recent studies have provided evidence that PH may develop in earlier stages of NAFLD, suggesting that there are additional pathogenetic mechanisms at work in addition to liver fibrosis. The early development of PH in NAFLD is associated with hepatocellular lipid accumulation and ballooning, leading to the compression of liver sinusoids. External compression and intra-luminal obstacles cause mechanical forces such as strain, shear stress and elevated hydrostatic pressure that in turn activate mechanotransduction pathways, resulting in endothelial dysfunction and the development of fibrosis. The spatial distribution of histological and functional changes in the periportal and perisinusoidal areas of the liver lobule are considered responsible for the pre-sinusoidal component of PH in patients with NAFLD. Thus, current diagnostic methods such as hepatic venous pressure gradient (HVPG) measurement tend to underestimate portal pressure (PP) in NAFLD patients, who might decompensate below the HVPG threshold of 10 mmHg, which is traditionally considered the most relevant indicator of clinically significant portal hypertension (CSPH). This creates further challenges in finding a reliable diagnostic method to stratify the prognostic risk in this population of patients. In theory, the measurement of the portal pressure gradient guided by endoscopic ultrasound might overcome the limitations of HVPG measurement by avoiding the influence of the pre-sinusoidal component, but more investigations are needed to test its clinical utility for this indication. Liver and spleen stiffness measurement in combination with platelet count is currently the best-validated non-invasive approach for diagnosing CSPH and varices needing treatment. Lifestyle change remains the cornerstone of the treatment of PH in NAFLD, together with correcting the components of metabolic syndrome, using nonselective beta blockers, whereas emerging candidate drugs require more robust confirmation from clinical trials.

Activation of cell adhesion and migration is an early event of platelet-rich plasma (PRP)-dependent stimulation of human adipose-derived stem/stromal cells

Stem cell therapy is a promising treatment in regenerative medicine. Human adipose-derived stem/stromal cells (hASCs), a type of mesenchymal stem cell, are easy to harvest. In plastic and aesthetic surgery, hASC may be applied in the treatment of fat grafting, wound healing, and scar remodeling. Platelet-rich plasma (PRP) contains various growth factors, including platelet-derived growth factor (PDGF), which accelerates wound healing. We previously reported that PRP promotes the proliferation of hASC via multiple signaling pathways, and we evaluated the effect of PRP on the stimulation of hASC adhesion and migration, leading to the proliferation of these cells. When hASCs were treated with PRP, AKT, ERK1/2, paxillin and RhoA were rapidly activated. PRP treatment led to the formation of F-actin stress fibers. Strong signals for integrin β1, paxillin and RhoA at the cell periphery of RPR-treated cells indicated focal adhesion. PRP promoted cell adhesion and movement of hASC, compared with the control group. Imatinib, an inhibitor of the PDGF receptor tyrosine kinase, inhibited the promotion of PRP-dependent cell migration. PDGF treatment of hASCs also stimulated cell adhesion and migration but to a lesser extent than PRP treatment. PRP promoted the adhesion and the migration of hASC, mediated by the activation of AKT in the integrin signaling pathway. PRP treatment was more effective than PDGF treatment in enhancing cell migration. Thus, the ability of PRPs to promote migration of hASC to enhance cell growth is evident.

Myo6 mediates osteoclast function and is essential for joint damage in collagen-induced arthritis

OBJECTIVES

To explore the novel function of MYO6 on Osteoclast differentiation and its joint destruction capacity in Rheumatoid arthritis mice model.

METHODS

We examined joint erosion in a collagen-induced arthritis (CIA) mouse model using micro-CT, with the mice having a MYO6 knockout background. Inflammatory cytokines were analyzed using an enzyme-linked immunosorbent assay (ELISA). In vitro, we investigated the osteoclastogenesis ability of bone marrow-derived macrophages isolated from MYO6-/- mice and their littermate controls, examining both morphological and functional differences. Furthermore, we explored podosome formation and endosome maturation using immunofluorescence staining.

RESULTS

We found that MYO6 deficiency attenuated arthritis development and bone destruction in CIA mice as well as impaired osteoclast differentiation by inhibiting NFATc1 induction. Our findings indicate that MYO6 is essential for the organization of podosomes by modulating the FAK/AKT and integrin-β3/Src pathways. MYO6 also mediates endosome transportation by regulating the expression of Rab5 and GM130. This may impact the maintenance and functionality of the ruffled border, as well as the regulation of autophagy in osteoclasts.

CONCLUSION

Our results demonstrated a critical function of MYO6 in osteoclast differentiation and its potential relevance in experimental arthritis.

Mechanobiology of portal hypertension

The interplay between mechanical stimuli and cellular mechanobiology orchestrates the physiology of tissues and organs in a dynamic balance characterized by constant remodelling and adaptative processes. Environmental mechanical properties can be interpreted as a complex set of information and instructions that cells read continuously, and to which they respond. In cirrhosis, chronic inflammation and injury drive liver cells dysfunction, leading to excessive extracellular matrix deposition, sinusoidal pseudocapillarization, vascular occlusion and parenchymal extinction. These pathological events result in marked remodelling of the liver microarchitecture, which is cause and result of abnormal environmental mechanical forces, triggering and sustaining the long-standing and progressive process of liver fibrosis. Multiple mechanical forces such as strain, shear stress, and hydrostatic pressure can converge at different stages of the disease until reaching a point of no return where the fibrosis is considered non-reversible. Thereafter, reciprocal communication between cells and their niches becomes the driving force for disease progression. Accumulating evidence supports the idea that, rather than being a passive consequence of fibrosis and portal hypertension (PH), mechanical force-mediated pathways could themselves represent strategic targets for novel therapeutic approaches. In this manuscript, we aim to provide a comprehensive review of the mechanobiology of PH, by furnishing an introduction on the most important mechanisms, integrating these concepts into a discussion on the pathogenesis of PH, and exploring potential therapeutic strategies.

Type I collagen proteolysis by matrix metalloproteinase-2 contributes to focal adhesion kinase activation and vascular smooth muscle cell proliferation in the aorta in early hypertension

INTRODUCTION

Increased matrix metalloproteinase (MMP)-2 activity contributes to increase vascular smooth muscle cell (VSMC) proliferation in the aorta in early hypertension by cleaving many proteins of the extracellular matrix. Cleaved products from type I collagen may activate focal adhesion kinases (FAK) that trigger migration and proliferation signals in VSMC. We therefore hypothesized that increased activity of MMP-2 proteolyzes type I collagen in aortas of hypertensive rats, and thereby, induces FAK activation, thus leading to increased VSMC proliferation and hypertrophic remodeling in early hypertension.

METHODS

Male Sprague-Dawley rats were submitted to renovascular hypertension by the two kidney-one clip (2K1C) model and treated with doxycycline (30 mg/kg/day) by gavage from the third to seventh-day post-surgery. Controls were submitted to sham surgery. Systolic blood pressure (SBP) was measured daily by tail-cuff plethysmography and the aortas were processed for zymography and Western blot for MMP-2, pFAK/FAK, integrins and type I collagen. Mass spectrometry, morphological analysis and Ki67 immunofluorescence were also done to identify collagen changes and VSMC proliferation. A7r5 cells were stimulated with collagen and treated with the MMP inhibitors (doxycycline or ARP-100), and with the FAK inhibitor PND1186 for 24 h. Cells were lysed and evaluated by Western blot for pFAK/FAK.

RESULTS

2K1C rats developed elevated SBP in the first week as well as increased expression and activity of MMP-2 in the aorta (p < 0.05 vs. Sham). Treatment with doxycycline reduced both MMP activity and type I collagen proteolysis in aortas of 2K1C rats (p < 0.05). Increased pFAK/FAK and increased VSMC proliferation (p < 0.05 vs. Sham groups) were also seen in the aortas of 2K1C and doxycycline decreased both parameters (p < 0.05). Higher proliferation of VSMC contributed to hypertrophic remodeling as seen by increased media/lumen ratio and cross sectional area (p < 0.05 vs Sham groups). In cell culture, MMP-2 cleaves collagen, an effect reversed by MMP inhibitors (p < 0.05). Increased levels of pFAK/FAK were observed when collagen was added in the culture medium (p < 0.05 vs control) and MMP and FAK inhibitors reduced this effect.

CONCLUSIONS

Increase in MMP-2 activity proteolyzes type I collagen in the aortas of 2K1C rats and contributes to activate FAK and induces VSMC proliferation during the initial phase of hypertension.

Identification of Rare Genetic Variants in Familial Spontaneous Coronary Artery Dissection and Evidence for Shared Biological Pathways

Rare familial spontaneous coronary artery dissection (SCAD) kindreds implicate genetic disease predisposition and provide a unique opportunity for candidate gene discovery. Whole-genome sequencing was performed in fifteen probands with non-syndromic SCAD who had a relative with SCAD, eight of whom had a second relative with extra-coronary arteriopathy. Co-segregating variants and associated genes were prioritized by quantitative variant, gene, and disease-level metrics. Curated public databases were queried for functional relationships among encoded proteins. Fifty-four heterozygous coding variants in thirteen families co-segregated with disease and fulfilled primary filters of rarity, gene variation constraint, and predicted-deleterious protein effect. Secondary filters yielded 11 prioritized candidate genes in 12 families, with high arterial tissue expression (n = 7), high-confidence protein-level interactions with genes associated with SCAD previously (n = 10), and/or previous associations with connective tissue disorders and aortopathies (n = 3) or other vascular phenotypes in mice or humans (n = 11). High-confidence associations were identified among 10 familial SCAD candidate-gene-encoded proteins. A collagen-encoding gene was identified in five families, two with distinct variants in COL4A2. Familial SCAD is genetically heterogeneous, yet perturbations of extracellular matrix, cytoskeletal, and cell-cell adhesion proteins implicate common disease-susceptibility pathways. Incomplete penetrance and variable expression suggest genetic or environmental modifiers.

BACH1 promotes lung adenocarcinoma cell metastasis through transcriptional activation of ITGA2

BACH1 plays an important role in promoting cancer. This study aims to further verify the relationship between the expression level of BACH1 in lung adenocarcinoma prognosis, as well as the influence of BACH1 expression on lung adenocarcinoma and the potential mechanism. The expression level of BACH1 in lung adenocarcinoma and its relationship with prognosis was evaluated by lung adenocarcinoma tissue microarray analysis combined with bioinformatics approaches. Gene knockdown and overexpression were used to investigate the functions and molecular mechanisms of BACH1 in lung adenocarcinoma cells. The regulatory downstream pathways and target genes of BACH1 in lung adenocarcinoma cells were explored by bioinformatics and RNA sequencing data analysis, real-time PCR, western blot analysis, and cell immunofluorescence and cell adhesion assays. Chromatin immunoprecipitation and dual-luciferase reporter assays were carried out to verify the target gene binding site. In the present study, BACH1 is abnormally highly expressed in lung adenocarcinoma tissues, and high BACH1 expression is negatively correlated with patient prognosis. BACH1 promotes the migration and invasion of lung adenocarcinoma cells. Mechanistically, BACH1 directly binds to the upstream sequence of the ITGA2 promoter to promote ITGA2 expression, and the BACH1-ITGA2 axis is involved in cytoskeletal regulation in lung adenocarcinoma cells by activating the FAK-RAC1-PAK signaling pathway. Our results indicated that BACH1 positively regulates the expression of ITGA2 through a transcriptional mechanism, thereby activating the FAK-RAC1-PAK signaling pathway to participate in the formation of the cytoskeleton in tumor cells and then promoting the migration and invasion of tumor cells.

Development of Mesoporous Silica Nanoparticle-Based Films with Tunable Arginine-Glycine-Aspartate Peptide Global Density and Clustering Levels to Study Stem Cell Adhesion and Differentiation

Stem cell adhesion is mediated via the binding of integrin receptors to adhesion motifs present in the extracellular matrix (ECM). The spatial organization of adhesion ligands plays an important role in stem cell integrin-mediated adhesion. In this study, we developed a series of biointerfaces using arginine-glycine-aspartate (RGD)-functionalized mesoporous silica nanoparticles (MSN-RGD) to study the effect of RGD adhesion ligand global density (ligand coverage over the surface), spacing, and RGD clustering levels on stem cell adhesion and differentiation. To prepare the biointerface, MSNs were chemically functionalized with RGD peptides via an antifouling poly(ethylene glycol) (PEG) linker. The RGD surface functionalization ratio could be controlled to create MSNs with high and low RGD ligand clustering levels. MSN films with varying RGD global densities could be created by blending different ratios of MSN-RGD and non-RGD-functionalized MSNs together. A computational simulation study was performed to analyze nanoparticle distribution and RGD spacing on the resulting surfaces to determine experimental conditions. Enhanced cell adhesion and spreading were observed when RGD global density increased from 1.06 to 5.32 nmol cm-2 using highly clustered RGD-MSN-based films. Higher RGD ligand clustering levels led to larger cell spreading and increased formation of focal adhesions. Moreover, a higher RGD ligand clustering level promoted the expression of alkaline phosphatase in hMSCs. Overall, these findings indicate that both RGD global density and clustering levels are crucial variables in regulating stem cell behaviors. This study provides important information about ligand-integrin interactions, which could be implemented into biomaterial design to achieve optimal performance of adhesive functional peptides.

The route of autophagy regulation by osteopontin: a review on the linking mechanisms

Autophagy is a dynamic intracellular process of protein degradation, which is mostly triggered by nutrient deprivation. This process initiates with the formation of autophagosomes, which they capture cytosolic material that is then degraded upon fusion with the lysosome. Several factors have been found to be associated with autophagy modulation, of which extracellular matrix (ECM) components has attracted the attention of recent studies. Osteopontin (OPN) is an important extracellular matrix component that has been detected in a wide range of tumor cells, and is involved in cancer cell invasion and metastasis. Recently, a number of studies have focused on the relationship of OPN with autophagy, by delineating the intracellular signaling pathways that connect OPN to the autophagy process. We will summarize signaling pathways and cell surface receptors, through which OPN regulates the process of autophagy.

Leishmania infection alters macrophage and dendritic cell migration in a three-dimensional environment

Background: Leishmaniasis results in a wide spectrum of clinical manifestations, ranging from skin lesions at the site of infection to disseminated lesions in internal organs, such as the spleen and liver. While the ability of Leishmania-infected host cells to migrate may be important to lesion distribution and parasite dissemination, the underlying mechanisms and the accompanying role of host cells remain poorly understood. Previously published work has shown that Leishmania infection inhibits macrophage migration in a 2-dimensional (2D) environment by altering actin dynamics and impairing the expression of proteins involved in plasma membrane-extracellular matrix interactions. Although it was shown that L. infantum induces the 2D migration of dendritic cells, in vivo cell migration primarily occurs in 3-dimensional (3D) environments. The present study aimed to investigate the migration of macrophages and dendritic cells infected by Leishmania using a 3-dimensional environment, as well as shed light on the mechanisms involved in this process. Methods: Following the infection of murine bone marrow-derived macrophages (BMDM), human macrophages and human dendritic cells by L. amazonensis, L. braziliensis, or L. infantum, cellular migration, the formation of adhesion complexes and actin polymerization were evaluated. Results: Our results indicate that Leishmania infection inhibited 3D migration in both BMDM and human macrophages. Reduced expression of proteins involved in adhesion complex formation and alterations in actin dynamics were also observed in Leishmania-infected macrophages. By contrast, increased human dendritic cell migration in a 3D environment was found to be associated with enhanced adhesion complex formation and increased actin dynamics. Conclusion: Taken together, our results show that Leishmania infection inhibits macrophage 3D migration, while enhancing dendritic 3D migration by altering actin dynamics and the expression of proteins involved in plasma membrane extracellular matrix interactions, suggesting a potential association between dendritic cells and disease visceralization.

Hax1 regulate focal adhesion dynamics through IQGAP1

Cell migration is a highly orchestrated process requiring the coordination between the cytoskeleton, cell membrane and extracellular matrix adhesions. Our previous study demonstrated that Hax1 interacts with EB2, a microtubule end-binding protein, and this interaction regulate cell migration in keratinocytes. However, little is known about the underlying regulatory mechanism. Here, we show that Hax1 links dynamic focal adhesions to regulate cell migration via interacting with IQGAP1, a multidomain scaffolding protein, which was identified by affinity purification coupled with LC-MS/MS. Biochemical characterizations revealed that C-terminal region of Hax1 and RGCT domain of IQGAP1 are the most critical binding determinants for its interaction. IQGAP1/Hax1 interaction is essential for cell migration in MCF7 cells. Knockdown of HAX1 not only stabilizes focal adhesions, but also impairs the accumulation of IQGAP in focal adhesions. Further study indicates that this interaction is critical for maintaining efficient focal adhesion turnover. Perturbation of the IQGAP1/Hax1 interaction in vivo using a membrane-permeable TAT-RGCT peptide results in impaired focal adhesion turnover, thus leading to inhibition of directional cell migration. Together, our findings unravel a novel interaction between IQGAP1 and Hax1, suggesting that IQGAP1 association with Hax1 plays a significant role in focal adhesion turnover and directional cell migration. Video Abstract.

SIX1 and EWS/FLI1 co-regulate an anti-metastatic gene network in Ewing Sarcoma

Ewing sarcoma (ES), which is characterized by the presence of oncogenic fusion proteins such as EWS/FLI1, is an aggressive pediatric malignancy with a high rate of early dissemination and poor outcome after distant spread. Here we demonstrate that the SIX1 homeoprotein, which enhances metastasis in most tumor types, suppresses ES metastasis by co-regulating EWS/FLI1 target genes. Like EWS/FLI1, SIX1 promotes cell growth/transformation, yet dramatically inhibits migration and invasion, as well as metastasis in vivo. We show that EWS/FLI1 promotes SIX1 protein expression, and that the two proteins share genome-wide binding profiles and transcriptional regulatory targets, including many metastasis-associated genes such as integrins, which they co-regulate. We further show that SIX1 downregulation of integrins is critical to its ability to inhibit invasion, a key characteristic of metastatic cells. These data demonstrate an unexpected anti-metastatic function for SIX1, through coordinate gene regulation with the key oncoprotein in ES, EWS/FLI1.

CSK-mediated signalling by integrins in cancer

Cancer progression and metastasis are processes heavily controlled by the integrin receptor family. Integrins are cell adhesion molecules that constitute the central components of mechanosensing complexes called focal adhesions, which connect the extracellular environment with the cell interior. Focal adhesions act as key players in cancer progression by regulating biological processes, such as cell migration, invasion, proliferation, and survival. Src family kinases (SFKs) can interplay with integrins and their downstream effectors. SFKs also integrate extracellular cues sensed by integrins and growth factor receptors (GFR), transducing them to coordinate metastasis and cell survival in cancer. The non-receptor tyrosine kinase CSK is a well-known SFK member that suppresses SFK activity by phosphorylating its specific negative regulatory loop (C-terminal Y⁵²⁷ residue). Consequently, CSK may play a pivotal role in tumour progression and suppression by inhibiting SFK oncogenic effects in several cancer types. Remarkably, CSK can localise near focal adhesions when SFKs are activated and even interact with focal adhesion components, such as phosphorylated FAK and Paxillin, among others, suggesting that CSK may regulate focal adhesion dynamics and structure. Even though SFK oncogenic signalling has been extensively described before, the specific role of CSK and its crosstalk with integrins in cancer progression, for example, in mechanosensing, remain veiled. Here, we review how CSK, by regulating SFKs, can regulate integrin signalling, and focus on recent discoveries of mechanotransduction. We additionally examine the cross talk of integrins and GFR as well as the membrane availability of these receptors in cancer. We also explore new pharmaceutical approaches to these signalling pathways and analyse them as future therapeutic targets.

Src stimulates Abl-dependent phosphorylation of the guanine exchange factor Net1A to promote its cytosolic localization and cell motility

The neuroepithelial cell transforming gene 1 (Net1) is a guanine nucleotide exchange factor for the small GTPase RhoA that promotes cancer cell motility and metastasis. Two isoforms of Net1 exist, Net1 and Net1A, both of which are sequestered in the nucleus in quiescent cells to prevent aberrant RhoA activation. Many cell motility stimuli drive cytosolic relocalization of Net1A, but mechanisms controlling this event are not fully understood. Here, we demonstrate that epithelial growth factor stimulates protein kinase Src- and Abl1-dependent phosphorylation of Net1A to promote its cytosolic localization. We show that Abl1 efficiently phosphorylates Net1A on Y373, and that phenylalanine substitution of Y373 prevents Net1A cytosolic localization. Furthermore, we found that Abl1-driven cytosolic localization of Net1A does not require S52, which is a phosphorylation site of a different kinase, c-Jun N-terminal kinase, that inhibits nuclear import of Net1A. However, we did find that MKK7-stimulated cytosolic localization of Net1A does require Y373. We also demonstrate that aspartate substitution at Y373 is sufficient to promote Net1A cytosolic accumulation, and expression of Net1A Y373D potentiates epithelial growth factor-stimulated RhoA activation, downstream myosin light chain 2 phosphorylation, and F-actin accumulation. Moreover, we show that expression of Net1A Y373D in breast cancer cells also significantly increases cell motility and Matrigel invasion. Finally, we show that Net1A is required for Abl1-stimulated cell motility, which is rescued by expression of Net1A Y373D, but not Net1A Y373F. Taken together, this work demonstrates a novel mechanism controlling Net1A subcellular localization to regulate RhoA-dependent cell motility and invasion.

Angiogenic signaling pathways and anti-angiogenic therapy for cancer

Angiogenesis, the formation of new blood vessels, is a complex and dynamic process regulated by various pro- and anti-angiogenic molecules, which plays a crucial role in tumor growth, invasion, and metastasis. With the advances in molecular and cellular biology, various biomolecules such as growth factors, chemokines, and adhesion factors involved in tumor angiogenesis has gradually been elucidated. Targeted therapeutic research based on these molecules has driven anti-angiogenic treatment to become a promising strategy in anti-tumor therapy. The most widely used anti-angiogenic agents include monoclonal antibodies and tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor (VEGF) pathway. However, the clinical benefit of this modality has still been limited due to several defects such as adverse events, acquired drug resistance, tumor recurrence, and lack of validated biomarkers, which impel further research on mechanisms of tumor angiogenesis, the development of multiple drugs and the combination therapy to figure out how to improve the therapeutic efficacy. Here, we broadly summarize various signaling pathways in tumor angiogenesis and discuss the development and current challenges of anti-angiogenic therapy. We also propose several new promising approaches to improve anti-angiogenic efficacy and provide a perspective for the development and research of anti-angiogenic therapy.

Single-Cell Profiling Uncovers the Roles of Endometrial Fibrosis and Microenvironmental Changes in Adenomyosis

Purpose

Adenomyosis (AM) is a common benign uterine disorder that has deleterious effects on women's health. However, the pathogenesis of AM is not clearly understood. We aimed to investigate the pathophysiological changes and molecular mechanism in AM.

Methods

Single-cell RNA sequencing (scRNA-seq) was employed to construct a transcriptomic atlas of various cell subsets from the ectopic endometrium (EC) and eutopic endometrium (EM) of one AM patient and evaluate differential expression. The Cell Ranger software pipeline (version 4.0.0) was applied to conduct sample demultiplexing, barcode processing and mapping reads to the reference genome (human GRCh38). Different cell types were classified with markers with the "FindAllMarkers" function, and differential gene expression analysis was performed with Seurat software in R. The findings were confirmed by Reverse Transcription Real-Time PCR using samples from three AM patients.

Results

We identified nine cell types: endothelial cells, epithelial cells, myoepithelial cells, smooth muscle cells, fibroblasts, lymphocytes, mast cells, macrophages and unknown cells. A number of differentially expressed genes, including CLO4A1, MMP1, TPM2 and CXCL8, were identified from all cell types. Functional enrichment showed that aberrant gene expression in fibroblasts and immune cells was related to fibrosis-associated terms, such as extracellular matrix dysregulation, focal adhesion and the PI3K-Akt signaling pathway. We also identified fibroblast subtypes and determined a potential developmental trajectory related to AM. In addition, we identified increased cell-cell communication patterns in EC, highlighting the imbalanced microenvironment in AM progression.

Conclusion

Our results support the theory of endometrial-myometrial interface disruption for AM, and repeated tissue injury and repair could lead to increased fibrosis in the endometrium. Therefore, the present study reveals the association between fibrosis, the microenvironment, and AM pathogenesis. This study provides insight into the molecular mechanisms regulating AM progression.

Phosphatase regenerating liver 3 participates in Integrinβ1/FAK-Src/MAPK signaling pathway and contributes to the regulation of malignant behaviors in hepatocellular carcinoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the leading cause of mortality worldwide. Phosphatase regenerating liver 3 (PRL-3) was associated with cancer metastasis. However, the significance of PRL-3 in the prognosis of HCC remains elusive. The aim of this study was to elucidate the role of PRL-3 in HCC metastasis and its prognosis.

METHODS

The expressions of PRL-3 in cancer tissues isolated from 114 HCC patients, who underwent curative hepatectomy from May to November in 2008, were analyzed by immunohistochemistry, and its prognostic significance was evaluated. Thereafter, the migration, invasion, and metastatic alterations in MHCC97H cells with PRL-3 overexpression or knockdown were explored and compared with the tumor size and lung metastasis in orthotopic HCC model of nude mice derived from MHCC97H cells with PRL-3 overexpression or knockdown. The underlying mechanism involving PRL-3-mediated effect on HCC migration, invasion, and metastasis was further examined.

RESULTS

Univariate and multivariate analysis demonstrated PRL-3 overexpression was an independent prognostic factor for poor overall survival (OS) and progression-free survival (PFS) of the HCC patients. Increased PRL-3 expression in MHCC97H cells was in accordance with the enhanced metastasis potential. PRL-3 knockdown inhibited the migration, invasiveness, and clone forming ability in MHCC97H cells, whereas PRL-3 overexpression reverted the above behavior. The growth of xenograft tumor in the liver was suppressed, and the lung metastasis in nude mice was inhibited by PRL-3 downregulation. The knockdown of PRL-3 could downregulate the expressions of Integrinβ1 and p-Src (Tyr416), p-Erk (Thr202/Tyr204) activation, and reduce MMP9 expression. Both MEK1/2 inhibitor (U0126) and Src inhibitor could repress PRL-3-induced invasiveness and migration in MHCC97H cells.

CONCLUSIONS

PRL-3 was significantly overexpressed and an independent prognostic factor to predict the death of HCC patients. Mechanically, PRL-3 plays a critical role in HCC invasive and metastasis via Integrinβ1/FAK-Src/RasMAPK signaling. Validation of PRL-3 as a clinical prediction marker in HCC warrants further research.

Uncovering a novel role of focal adhesion and interferon-gamma in cellular rejection of kidney allografts at single cell resolution

Background

Kidney transplant recipients are currently treated with nonspecific immunosuppressants that cause severe systemic side effects. Current immunosuppressants were developed based on their effect on T-cell activation rather than the underlying mechanisms driving alloimmune responses. Thus, understanding the role of the intragraft microenvironment will help us identify more directed therapies with lower side effects.

Methods

To understand the role of the alloimmune response and the intragraft microenvironment in cellular rejection progression, we conducted a Single nucleus RNA sequencing (snRNA-seq) on one human non-rejecting kidney allograft sample, one borderline sample, and T-cell mediated rejection (TCMR) sample (Banff IIa). We studied the differential gene expression and enriched pathways in different conditions, in addition to ligand-receptor (L-R) interactions.

Results

Pathway analysis of T-cells in borderline sample showed enrichment for allograft rejection pathway, suggesting that the borderline sample reflects an early rejection. Hence, this allows for studying the early stages of cellular rejection. Moreover, we showed that focal adhesion (FA), IFNg pathways, and endomucin (EMCN) were significantly upregulated in endothelial cell clusters (ECs) of borderline compared to ECs TCMR. Furthermore, we found that pericytes in TCMR seem to favor endothelial permeability compared to borderline. Similarly, T-cells interaction with ECs in borderline differs from TCMR by involving DAMPS-TLRs interactions.

Conclusion

Our data revealed novel roles of T-cells, ECs, and pericytes in cellular rejection progression, providing new clues on the pathophysiology of allograft rejection.

Cell response to mechanical microenvironment cues via Rho signaling: From mechanobiology to mechanomedicine

Mechanical cues in the cell microenvironment such as those from extracellular matrix properties, stretching, compression and shear stress, play a critical role in maintaining homeostasis. Upon sensing mechanical stimuli, cells can translate these external forces into intracellular biochemical signals to regulate their cellular behaviors, but the specific mechanisms of mechanotransduction at the molecular level remain elusive. As a subfamily of the Ras superfamily, Rho GTPases have been recognized as key intracellular mechanotransduction mediators that can regulate multiple cell activities such as proliferation, migration and differentiation as well as biological processes such as cytoskeletal dynamics, metabolism, and organ development. However, the upstream mechanosensors for Rho proteins and downstream effectors that respond to Rho signal activation have not been well illustrated. Moreover, Rho-mediated mechanical signals in previous studies are highly context-dependent. In this review, we systematically summarize the types of mechanical cues in the cell microenvironment and provide recent advances on the roles of the Rho-based mechanotransduction in various cell activities, physiological processes and diseases. Comprehensive insights into the mechanical roles of Rho GTPase partners would open a new paradigm of mechanomedicine for a variety of diseases. STATEMENT OF SIGNIFICANCE: In this review, we highlight the critical role of Rho GTPases as signal mediators to respond to physical cues in microenvironment. This article will add a distinct contribution to this set of knowledge by intensively addressing the relationship between Rho signaling and mechanobiology/mechanotransduction/mechanomedcine. This topic has not been discussed by the journal, nor has it yet been developed by the field. The comprehensive picture that will develop, from molecular mechanisms and engineering methods to disease treatment strategies, represents an important and distinct contribution to the field. We hope that this review would help researchers in various fields, especially clinicians, oncologists and bioengineers, who study Rho signal pathway and mechanobiology/mechanotransduction, understand the critical role of Rho GTPase in mechanotransduction.

S100A8/S100A9 Integrates F-Actin and Microtubule Dynamics to Prevent Uncontrolled Extravasation of Leukocytes

Immune reactions are characterized by the rapid immigration of phagocytes into sites of inflammation. Meticulous regulation of these migratory processes is crucial for preventing uncontrolled and harmful phagocyte extravasation. S100A8/S100A9 is the major calcium-binding protein complex expressed in phagocytes. After release, this complex acts as a proinflammatory alarmin in the extracellular space, but the intracellular functions of these highly abundant proteins are less clear. Results of this study reveal an important role of S100A8/S100A9 in coordinated cytoskeleton rearrangement during migration. We found that S100A8/S100A9 was able to cross-link F-actin and microtubules in a calcium- and phosphorylation-dependent manner. Cells deficient in S100A8/S100A9 showed abnormalities in cell adhesion and motility. Missing cytoskeletal interactions of S100A8/S100A9 caused differences in the surface expression and activation of β1-integrins as well as in the regulation of Src/Syk kinase family members. Loss of S100A8/S100A9 led to dysregulated integrin-mediated adhesion and migration, resulting in an overall higher dynamic activity of non-activated S100A8/S100A9-deficient phagocytes. Our data suggest that intracellular S100A8/S100A9 is part of a novel regulatory mechanism that ensures the precise control necessary to facilitate the change between the quiescent and activated state of phagocytes.

Machilin D Promotes Apoptosis and Autophagy, and Inhibits Necroptosis in Human Oral Squamous Cell Carcinoma Cells

Oral squamous cell carcinoma (OSCC) accounts for about 90% of all head and neck cancers, the prognosis is very poor, and there are no effective targeted therapies. Herein, we isolated Machilin D (Mach), a lignin, from the roots of Saururus chinensis (S. chinensis) and assessed its inhibitory effects on OSCC. Herein, Mach had significant cytotoxicity against human OSCC cells and showed inhibitory effects against cell adhesion, migration, and invasion by inhibiting adhesion molecules, including the FAK/Src pathway. Mach suppressed the PI3K/AKT/mTOR/p70S6K pathway and MAPKs, leading to apoptotic cell death. We investigated other modes of programmed cell death in these cells and found that Mach increased LC3I/II and Beclin1 and decreased p62, leading to autophagosomes, and suppressed the necroptosis-regulatory proteins RIP1 and MLKL. Our findings provide evidence that the inhibitory effects of Mach against human YD-10B OSCC cells are related to the promotion of apoptosis and autophagy and inhibition of necroptosis and are mediated via focal adhesion molecules.

The Role of Autophagy in Breast Cancer Metastasis

Patient morbidity and mortality is significantly increased in metastatic breast cancer. The metastasis process of breast cancer is very complicated and is delicately controlled by various factors. Autophagy is one of the important regulatory factors affecting metastasis in breast cancer by engaging in cell mobility, metabolic adaptation, tumor dormancy, and cancer stem cells. Here, we discuss the effects of autophagy on metastasis in breast cancer and assess the potential use of autophagy modulators for metastasis treatment.

The emerging role of microtubules in invasion plasticity

The ability of cells to switch between different invasive modes during metastasis, also known as invasion plasticity, is an important characteristic of tumor cells that makes them able to resist treatment targeted to a particular invasion mode. Due to the rapid changes in cell morphology during the transition between mesenchymal and amoeboid invasion, it is evident that this process requires remodeling of the cytoskeleton. Although the role of the actin cytoskeleton in cell invasion and plasticity is already quite well described, the contribution of microtubules is not yet fully clarified. It is not easy to infer whether destabilization of microtubules leads to higher invasiveness or the opposite since the complex microtubular network acts differently in diverse invasive modes. While mesenchymal migration typically requires microtubules at the leading edge of migrating cells to stabilize protrusions and form adhesive structures, amoeboid invasion is possible even in the absence of long, stable microtubules, albeit there are also cases of amoeboid cells where microtubules contribute to effective migration. Moreover, complex crosstalk of microtubules with other cytoskeletal networks participates in invasion regulation. Altogether, microtubules play an important role in tumor cell plasticity and can be therefore targeted to affect not only cell proliferation but also invasive properties of migrating cells.

Phosphorylation/dephosphorylation of PTP-PEST at Serine 39 is crucial for cell migration

We investigated the molecular details of the role of protein tyrosine phosphatase (PTP)-PEST in cell migration. PTP-PEST knockout mouse embryonic fibroblasts (KO MEFs) and MEF cells expressing a dominant-negative mutant of PTP-PEST showed significant suppression of cell migration compared to MEF cells expressing wild-type PTP-PEST (WT MEFs). Moreover, MEF cells harbouring a constitutively active mutant of PTP-PEST (S39A MEFs) showed a marked decrease in cell migration. In addition, MEF cells with no PTP-PEST or little PTP activity rapidly adhered to fibronectin and made many focal adhesions compared to WT MEF cells. In contrast, S39A MEF cells showed weak adhesion to fibronectin and formed a few focal adhesions. Furthermore, investigating the subcellular localization showed that Ser39-phosphorylated PTP-PEST was favourably situated in the adherent area of the pseudopodia. Therefore, we propose that suppression of PTP-PEST enzyme activity due to Ser39-phosphorylation in pseudopodia and at the leading edge of migrating cells induces rapid and good adherence to the extracellular matrix. Thus, suppression of PTP activity by Ser39-phosphorylation is critical for cell migration. Three amino acid substitutions in human PTP-PEST have been previously reported to alter PTP activity. These amino acid substitutions in mouse PTP-PEST altered the migration of MEF cells in a positive correlation.

Targeting integrin pathways: mechanisms and advances in therapy

Integrins are considered the main cell-adhesion transmembrane receptors that play multifaceted roles as extracellular matrix (ECM)-cytoskeletal linkers and transducers in biochemical and mechanical signals between cells and their environment in a wide range of states in health and diseases. Integrin functions are dependable on a delicate balance between active and inactive status via multiple mechanisms, including protein-protein interactions, conformational changes, and trafficking. Due to their exposure on the cell surface and sensitivity to the molecular blockade, integrins have been investigated as pharmacological targets for nearly 40 years, but given the complexity of integrins and sometimes opposite characteristics, targeting integrin therapeutics has been a challenge. To date, only seven drugs targeting integrins have been successfully marketed, including abciximab, eptifibatide, tirofiban, natalizumab, vedolizumab, lifitegrast, and carotegrast. Currently, there are approximately 90 kinds of integrin-based therapeutic drugs or imaging agents in clinical studies, including small molecules, antibodies, synthetic mimic peptides, antibody-drug conjugates (ADCs), chimeric antigen receptor (CAR) T-cell therapy, imaging agents, etc. A serious lesson from past integrin drug discovery and research efforts is that successes rely on both a deep understanding of integrin-regulatory mechanisms and unmet clinical needs. Herein, we provide a systematic and complete review of all integrin family members and integrin-mediated downstream signal transduction to highlight ongoing efforts to develop new therapies/diagnoses from bench to clinic. In addition, we further discuss the trend of drug development, how to improve the success rate of clinical trials targeting integrin therapies, and the key points for clinical research, basic research, and translational research.

Brain metastatic outgrowth and osimertinib resistance are potentiated by RhoA in EGFR-mutant lung cancer

The brain is a major sanctuary site for metastatic cancer cells that evade systemic therapies. Through pre-clinical pharmacological, biological, and molecular studies, we characterize the functional link between drug resistance and central nervous system (CNS) relapse in Epidermal Growth Factor Receptor- (EGFR-) mutant non-small cell lung cancer, which can progress in the brain when treated with the CNS-penetrant EGFR inhibitor osimertinib. Despite widespread osimertinib distribution in vivo, the brain microvascular tumor microenvironment (TME) is associated with the persistence of malignant cell sub-populations, which are poised to proliferate in the brain as osimertinib-resistant lesions over time. Cellular and molecular features of this poised state are regulated through a Ras homolog family member A (RhoA) and Serum Responsive Factor (SRF) gene expression program. RhoA potentiates the outgrowth of disseminated tumor cells on osimertinib treatment, preferentially in response to extracellular laminin and in the brain. Thus, we identify pre-existing and adaptive features of metastatic and drug-resistant cancer cells, which are enhanced by RhoA/SRF signaling and the brain TME during the evolution of osimertinib-resistant disease.