Guanine Nucleotide Exchange Factor Vav1 Research Articles

Key mRNAs and lncRNAs of pituitary that affect the reproduction of FecB + + small tail han sheep

BackgroundThe pituitary directly regulates the reproductive process through follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Transcriptomic research on the pituitaries of ewes with different FecB (fecundity Booroola) genotypes has shown that some key genes and lncRNAs play an important role in pituitary function and sheep fecundity. Our previous study found that ewes with FecB + + genotypes (without FecB mutation) still had individuals with more than one offspring per birth. It is hoped to analyze this phenomenon from the perspective of the pituitary transcriptome.ResultsThe 12 Small Tail Han Sheep were equally divided into polytocous sheep in the follicular phase (PF), polytocous sheep in the luteal phase (PL), monotocous sheep in the follicular phase (MF), and monotocous sheep in the luteal phase (ML). Pituitary tissues were collected after estrus synchronous treatment for transcriptomic analysis. A total of 384 differentially expressed genes (DEGs) (182 in PF vs. MF and 202 in PL vs. ML) and 844 differentially expressed lncRNAs (DELs) (427 in PF vs. MF and 417 in PL vs. ML) were obtained from the polytocous-monotocous comparison groups in the two phases. Functional enrichment analysis showed that the DEGs in the two phases were enriched in signaling pathways known to play an important role in sheep fecundity, such as calcium ion binding and cAMP signaling pathways. A total of 1322 target relationship pairs (551 pairs in PF vs. MF and 771 pairs in PL vs. ML) were obtained for the target genes prediction of DELs, of which 29 DEL-DEG target relationship pairs (nine pairs in PF vs. MF and twenty pairs in PL vs. ML). In addition, the competing endogenous RNA (ceRNA) networks were constructed to explore the regulatory relationships of DEGs, and some important regulatory relationship pairs were obtained.ConclusionAccording to the analysis results, we hypothesized that the pituitary first receives steroid hormone signals from the ovary and uterus and that VAV3 (Vav Guanine Nucleotide Exchange Factor 3), GABRG1 (Gamma-Aminobutyric Acid A Receptor, Gamma 1), and FNDC1 (Fibronectin Type III Domain Containing 1) played an important role in this process. Subsequently, the reproductive process was regulated by gonadotropins, and IGFBP1 (Insulin-like Growth Factor Binding Protein 1) was directly involved in this process, ultimately affecting litter size. In addition, TGIF1 (Transforming Growth Factor-Beta-Induced Factor 1) and TMEFF2 (Transmembrane Protein With EGF Like And Two Follistatin Like Domains 2) compensated for the effect of the FecB mutation and function by acting on TGF-β/SMAD signaling pathway, an important pathway for sheep reproduction. These results provided a reference for understanding the mechanism of multiple births in Small Tail Han Sheep without FecB mutation.

Whole-genome DNA methylation profiling reveals epigenetic signatures in developing muscle in Tan and Hu sheep and their offspring.

The Tan sheep is a popular local breed in China because of its tenderness and flavor. The Hu sheep breed is also famous for its high litter size, and its muscle growth rate is faster than that of Tan sheep. However, the epigenetic mechanism behind these muscle-related phenotypes is unknown. In this study, the longissimus dorsi tissue from 18 6 month-old Tan sheep, Hu sheep, and Tan-Hu F2 generation (6 sheep per population) were collected. After genomic DNA extraction, whole-genome bisulfite sequencing (WGBS) and bioinformatics analysis were performed to construct genome-wide DNA methylome maps for the Tan sheep, Hu sheep and their Tan-Hu F2 generation. Distinct genome-wide DNA methylation patterns were observed between Tan sheep and Hu sheep. Moreover, DNA methylated regions were significantly increased in the skeletal muscle from Tan sheep vs. the F2 generation compared to the Hu sheep vs. F2 generation and the Tan sheep vs. Hu sheep. Compared with Hu sheep, the methylation levels of actin alpha 1 (ACTA1), myosin heavy chain 11 (MYH11), Wiskott-Aldrich syndrome protein (WAS), vav guanine nucleotide exchange factor 1 (VAV1), fibronectin 1 (FN1) and Rho-associated protein kinase 2 (ROCK2) genes were markedly distinct in the Tan sheep. Furthermore, Gene Ontology analysis indicated that these genes were involved in myotube differentiation, myotube cell development, smooth muscle cell differentiation and striated muscle cell differentiation. The findings from this study, in addition to data from previous research, demonstrated that the ACTA1, MYH11, WAS, VAV1, FN1, and ROCK2 genes may exert regulatory effects on muscle development.

Cymbaria daurica L.: A Mongolian herbal medicine for treating eczema via natural killer cell-mediated cytotoxicity pathway.

Cymbaria daurica L. (C. daurica) is a perennial herb known commonly as "Xinba" (Chinese) and "Kanba-Arong" (Mongolian). In Mongolia, it is used as a traditional medicine to treat eczema and other skin diseases due to its anti-swelling, anti-inflammatory, anti-hemorrhagic, and anti-itching properties. However, the potential mechanism of action for eczema treatment has not been reported. To investigate the effect of C. daurica on 1-chloro-2,4-dinitrobenzene (DNCB)-induced eczema in rats and the associated action mechanism. Qualitative analysis of C. daurica was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on information obtained from compound identification and relevant literature, the possible targets of C. daurica against eczema were analyzed using network pharmacology and molecular docking methods. The DNCB-induced eczema rat models were treated with different dosages of C. daurica extract (10, 50, and 250mg/mL per day), and the therapeutic effects subsequently evaluated based on the degree of skin inflammation, spleen index, and hematoxylin and eosin staining (H&E staining). Enzyme-linked immunosorbent assay (ELISA), reverse transcription quantitative polymerase chain reaction (RT-qPCR), and western blotting were used to analyze the relevant target effects. The C. daurica mechanism of action on eczema was verified by animal experiments. High-performance liquid chromatography (HPLC) was carried out to determine the content of active ingredients in C. daurica. In addition, the physicochemical properties of the extract were evaluated. Our analysis of the 173 targets included in the protein-protein interaction (PPI) network identified tumor necrosis factor (TNF) and interleukin 2 (IL-2) as key targets involved in the treatment of eczema with C. daurica extract. Furthermore, the 173 targets were associated with the natural killer cell-mediated cytotoxicity pathway. Our results showed that C. daurica significantly reduced IL-2 and TNF-α serum levels in eczema rat models (P<0.0001); thus, playing an important role in the anti-inflammatory response. Furthermore, according to the p-value, RT-qPCR and western blotting showed that the expression of Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1), Vav guanine nucleotide exchange factor (Vav), and growth factor receptor-bound protein 2 (Grb2) changed in the skin of the eczema model rats after treatment with the C. daurica extract. Our study confirms that C. daurica can inhibit SHP-1, Vav, and Grb2 expression; thereby, inhibiting the natural killer cell-mediated cytotoxicity pathway. These results provide insight into the mechanism of C. daurica in treating eczema.

VAV3 regulates glioblastoma cell proliferation, migration, invasion and cancer stem‑like cell self‑renewal.

Glioblastoma multiforme (GBM; World Health Organization grade IV) is one of the most common and aggressive malignant brain tumors and has no effective treatment. Therefore, elucidation of the molecular mechanism of glioma development is very important for finding new therapeutic strategies. The present study evaluated the expression level of Vav guanine nucleotide exchange factor 3 (VAV3) using bioinformatics analysis and demonstrated that VAV3 was overexpressed in human glioblastoma and associated with patient survival. Knock down of VAV3 using shRNA in glioblastoma cells significantly inhibited glioblastoma cell migration, invasion and proliferation. Furthermore, downregulation of VAV3 expression inhibited the stem cell self‑renewal capacity and decreased the expression levels of the stem cell markers Nestin and Sox2. Bioinformatic analysis demonstrated that VAV3 was a target gene of miR‑218. Furthermore, overexpression of VAV3 markedly reversed the tumor suppressor effect of miR‑218 in glioblastoma cell. These findings suggested that VAV3 could be a potential biomarker and therapeutic target for glioblastoma.

Vav1 promotes inflammation and neuronal apoptosis in cerebral ischemia/reperfusion injury by upregulating microglial and NLRP3 inflammasome activation.

Microglia, which are the resident macrophages of the central nervous system, are an important part of the inflammatory response that occurs after cerebral ischemia. Vav guanine nucleotide exchange factor 1 (Vav1) is a guanine nucleotide exchange factor that is related to microglial activation. However, how Vav1 participates in the inflammatory response after cerebral ischemia/reperfusion injury remains unclear. In this study, we subjected rats to occlusion and reperfusion of the middle cerebral artery and subjected the BV-2 microglia cell line to oxygen-glucose deprivation/reoxygenation to mimic cerebral ischemia/reperfusion in vivo and in vitro, respectively. We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral artery and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation. Silencing Vav1 reduced the cerebral infarct volume and brain water content, inhibited neuronal loss and apoptosis in the ischemic penumbra, and improved neurological function in rats subjected to occlusion and reperfusion of the middle cerebral artery. Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3 (NLRP3) inflammasome in the ischemic penumbra, as well as the expression of inflammatory factors. In addition, Vav1 knockdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxygenation. Taken together, these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/reperfusion through inhibiting the activation of microglia and NLRP3 inflammasome.

The fusion oncogene VAV1-MYO1F triggers aberrant T-cell receptor signaling in vivo and drives peripheral T-cell lymphoma in mice.

VAV1-MYO1F is a recently identified gain-of-function fusion protein of the proto-oncogene Vav guanine nucleotide exchange factor 1 (VAV1) that is recurrently detected in T-cell non-Hodgkin's lymphoma (T-NHL) patients. However, the pathophysiological functions of VAV1-MYO1F in lymphomagenesis are insufficiently defined. Therefore, we generated transgenic mouse models to conditionally express VAV1-MYO1F in T-cells in vivo. We demonstrate that VAV1-MYO1F triggers cell autonomous activation of T-cell signaling with an activation of the ERK, JNK, and AKT pathways. VAV1-MYO1F expression induces a T-cell activation phenotype with high surface expression of CD25, ICOS, CD44, PD-1, and decreased CD62L as well as aberrant T-cell differentiation, proliferation, and neoplastic transformation. Consequently, the VAV1-MYO1F expressing T-cells induce a malignant T lymphoproliferative disease with 100% penetrance in vivo that mimics key aspects of human peripheral T-cell lymphoma. These results demonstrate that the human T-cell oncogene VAV1-MYO1F is sufficient to trigger oncogenic T-cell signaling and neoplastic transformation, and moreover, it provides a new clinically relevant mouse model to explore the pathogenesis of and treatment concepts for human T-cell lymphoma.

Targeting HuR-Vav3 mRNA interaction prevents Pseudomonas aeruginosa adhesion to the cystic fibrosis airway epithelium

Cystic fibrosis (CF) is characterized by chronic bacterial infections leading to progressive bronchiectasis and respiratory failure. Pseudomonas aeruginosa (Pa) is the predominant opportunistic pathogen infecting the CF airways. The guanine nucleotide exchange factor Vav3 plays a critical role in Pa adhesion to the CF airways by inducing luminal fibronectin deposition that favors bacteria trapping. Here we report that Vav3 overexpression in CF is caused by upregulation of the mRNA-stabilizing protein HuR. We found that HuR accumulates in the cytoplasm of CF airway epithelial cells and that it binds to and stabilizes Vav3 mRNA. Interestingly, disruption of the HuR-Vav3 mRNA interaction improved the CF epithelial integrity, inhibited the formation of the fibronectin-made bacterial docking platforms, and prevented Pa adhesion to the CF airway epithelium. These findings indicate that targeting HuR represents a promising antiadhesive approach in CF that can prevent initial stages of Pa infection in a context of emergence of multidrug-resistant pathogens.

AFAP1L1 promotes gastric cancer progression by interacting with VAV2 to facilitate CDC42-mediated activation of ITGA5 signaling pathway

BackgroundThe actin filament-associated protein (AFAP) family genes include AFAP1/AFAP-110, AFAP1L1 and AFAP1L2/XB130. Increasing evidence indicates these three AFAP family members participate in tumor progression, but their clinical significance and molecular mechanisms in gastric cancer (GC) remain unclear.MethodsWe first analyzed expression of AFAP family genes using public datasets and verified the results. The clinical significance of AFAP family genes in GC patients was also analyzed. In vitro and in vivo experiments were applied to explore the function of AFAP1L1. Enrichment analysis was used to explore potential molecular mechanisms. We then performed additional experiments, such as cell adhesion assay, co-immunoprecipitation and so on to confirm the downstream molecular mechanisms of AFAP1L1.ResultsPublic data analyses and our verification both showed AFAP1L1 was the only AFAP family members that was significantly upregulated in GC compared with normal gastric tissues. Besides, only AFAP1L1 could predict poor prognosis and act as an independent risk factor for GC patients. In addition, AFAP1L1 promotes GC cells proliferation, migration, invasion in vitro and tumor growth, metastasis in vivo by inducing epithelial-to-mesenchymal transition (EMT). In terms of mechanism, AFAP1L1 interacts with VAV guanine nucleotide exchange factor 2 (VAV2) to activate Rho family GTPases CDC42, which finally promotes expression of integrin subunit alpha 5 (ITGA5) and activation of integrin signaling pathway.ConclusionAFAP1L1 promotes GC progression by inducing EMT through VAV2-mediated activation of CDC42 and ITGA5 signaling pathway, indicating AFAP1L1 may be a promising prognostic biomarker and therapeutic target for GC patients.

Characterization of Novel Derivatives of MBQ-167, an inhibitor of the GTP-binding proteins Rac/Cdc42.

Rac and Cdc42, are homologous GTPases that regulate cell migration, invasion, and cell cycle progression; thus, representing key targets for metastasis therapy. We previously reported on the efficacy of MBQ-167, which blocks both Rac1 and Cdc42 in breast cancer cells and mouse models of metastasis. To identify compounds with increased activity, a panel of MBQ-167 derivatives was synthesized, maintaining its 9-ethyl-3-(1H-1,2,3-triazol-1-yl)-9H-carbazole core. Similar to MBQ-167, MBQ-168 and EHop-097, inhibit activation of Rac and Rac1B splice variant and breast cancer cell viability, and induce apoptosis. MBQ-167 and MBQ-168 inhibit Rac and Cdc42 by interfering with guanine nucleotide binding, and MBQ-168 is a more effective inhibitor of PAK (1,2,3) activation. EHop-097 acts via a different mechanism by inhibiting the interaction of the guanine nucleotide exchange factor (GEF) Vav with Rac. MBQ-168 and EHop-097 inhibit metastatic breast cancer cell migration, and MBQ-168 promotes loss of cancer cell polarity to result in disorganization of the actin cytoskeleton and detachment from the substratum. In lung cancer cells, MBQ-168 is more effective than MBQ-167 or EHop-097 at reducing ruffle formation in response to EGF. Comparable to MBQ-167, MBQ-168 significantly inhibits HER2+ tumor growth and metastasis to lung, liver, and spleen. Both MBQ-167 and MBQ-168 inhibit the cytochrome P450 (CYP) enzymes 3A4, 2C9, and 2C19. However, MBQ-168 is ~10X less potent than MBQ-167 at inhibiting CYP3A4, thus demonstrating its utility in relevant combination therapies. In conclusion, the MBQ-167 derivatives MBQ-168 and EHop-097 are additional promising anti metastatic cancer compounds with similar and distinct mechanisms.

Cortactin: A universal host cytoskeletal target of Gram-negative and Gram-positive bacterial pathogens.

Pathogenic bacteria possess a great potential of causing infectious diseases and represent a serious threat to human and animal health. Understanding the molecular basis of infection development can provide new valuable strategies for disease prevention and better control. In host-pathogen interactions, actin-cytoskeletal dynamics play a crucial role in the successful adherence, invasion, and intracellular motility of many intruding microbial pathogens. Cortactin, a major cellular factor that promotes actin polymerization and other functions, appears as a central regulator of host-pathogen interactions and different human diseases including cancer development. Various important microbes have been reported to hijack cortactin signaling during infection. The primary regulation of cortactin appears to proceed via serine and/or tyrosine phosphorylation events by upstream kinases, acetylation, and interaction with various other host proteins, including the Arp2/3 complex, filamentous actin, the actin nucleation promoting factor N-WASP, focal adhesion kinase FAK, the large GTPase dynamin-2, the guanine nucleotide exchange factor Vav2, and the actin-stabilizing protein CD2AP. Given that many signaling factors can affect cortactin activities, several microbes target certain unique pathways, while also sharing some common features. Here we review our current knowledge of the hallmarks of cortactin as a major target for eminent Gram-negative and Gram-positive bacterial pathogens in humans.

The guanine nucleotide exchange factor Vav3 intervenes in the migration pathway of oligodendrocyte precursor cells on tenascin-C.

Oligodendrocyte precursor cells (OPCs) are the exclusive source of myelination in the central nervous system (CNS). Prior to myelination, OPCs migrate to target areas and mature into myelinating oligodendrocytes. This process is underpinned by drastic changes of the cytoskeleton and partially driven by pathways involving small GTPases of the Rho subfamily. In general, the myelination process requires migration, proliferation and differentiation of OPCs. Presently, these processes are only partially understood. In this study, we analyzed the impact of the guanine nucleotide exchange factor (GEF) Vav3 on the migration behavior of OPCs. Vav3 is known to regulate RhoA, Rac1 and RhoG activity and is therefore a promising candidate with regard to a regulatory role concerning the rearrangement of the cytoskeleton. Our study focused on the Vav3 knockout mouse and revealed an enhanced migration capacity of Vav3 -/- OPCs on the extracellular matrix (ECM) glycoprotein tenascin-C (TnC). The migration behavior of individual OPCs on further ECM molecules such as laminin-1 (Ln1), laminin-2 (Ln2) and tenascin-R (TnR) was not affected by the elimination of Vav3. The migration process was further investigated with regard to intracellular signal transmission by pharmacological blockade of downstream pathways of specific Rho GTPases. Our data suggest that activation of RhoA GTPase signaling compromises migration, as inhibition of RhoA-signaling promoted migration behavior. This study provides novel insights into the control of OPC migration, which could be useful for further understanding of the complex differentiation and myelination process.

Mutations Affecting Genes in the Proximal T-Cell Receptor Signaling Pathway in Peripheral T-Cell Lymphoma.

Simple SummaryThe advent of next-generation sequencing (NGS) has allowed rapid advances in genomic studies on the pathogenesis and biology of peripheral T-cell lymphoma (PTCL). Recurrent mutations and fusions in genes related to the proximal TCR signaling pathway have been identified and show an important pathogenic role in PTCL. In this review, we summarize the genomic alterations in TCR signaling identified in different subgroups of PTCL patients and the functional impact of these alterations on TCR signaling and downstream pathways. We also discuss novel agents that could target TCR-related mutations and may hold promise for improving the treatment of PTCL.Peripheral T-cell lymphoma (PTCL) comprises a heterogeneous group of mature T-cell malignancies. Recurrent activating mutations and fusions in genes related to the proximal TCR signaling pathway have been identified in preclinical and clinical studies. This review summarizes the genetic alterations affecting proximal TCR signaling identified from different subgroups of PTCL and the functional impact on TCR signaling and downstream pathways. These genetic abnormalities include mostly missense mutations, occasional indels, and gene fusions involving CD28, CARD11, the GTPase RHOA, the guanine nucleotide exchange factor VAV1, and kinases including FYN, ITK, PLCG1, PKCB, and PI3K subunits. Most of these aberrations are activating mutations that can potentially be targeted by inhibitors, some of which are being tested in clinical trials that are briefly outlined in this review. Finally, we focus on the molecular pathology of recently identified subgroups of PTCL-NOS and highlight the unique genetic profiles associated with PTCL-GATA3.

Morin Disrupts Cytoskeleton Reorganization in Osteoclasts through an ROS/SHP1/c-Src Axis and Grants Protection from LPS-Induced Bone Loss.

Morin is a naturally occurring flavonoid with anti-inflammatory and antioxidative properties. Therefore, we hypothesized that morin may prevent inflammatory bone loss by reducing oxidative stress. To investigate the effect of morin on inflammatory bone loss, mice were injected with lipopolysaccharide (LPS). Osteoclasts (OCs) were analyzed by tartrate-resistant acid phosphatase (TRAP) staining and actin ring formation. Micro-computerized tomography analysis indicated that morin prevented LPS-induced bone loss in mice. In vivo TRAP staining indicated that morin decreased the number and surface of the OCs that were increased in LPS-treated mice. Furthermore, in vitro experiments indicated that morin decreased the number and activity of OCs upon LPS stimulation. Morin decreased actin ring-containing OCs with decreased activation of c-Src (Y416)/vav guanine nucleotide exchange factor 3/Ras-related C3 botulinum toxin substrate 1 compared with LPS alone. Morin decreased cytosolic reactive oxygen species (ROS), thus preventing the oxidation of Src homology region 2 domain-containing phosphatase 1 (SHP-1), followed by the inactivation of c-Src via direct interaction with SHP1. Conversely, SHP1 knockdown abolished the inhibitory effect of morin on OCs. Therefore, our findings suggest that morin disrupted cytoskeletal reorganization via an ROS/SHP1/c-Src axis in OCs, thereby granting protection from LPS-induced bone loss, which demonstrates its therapeutic potential against inflammatory bone loss.

Targeting CCL2-CCR4 axis suppress cell migration of head and neck squamous cell carcinoma

For head and neck squamous cell carcinoma (HNSCC), the local invasion and distant metastasis represent the predominant causes of mortality. Targeted inhibition of chemokines and their receptors is an ongoing antitumor strategy established on the crucial roles of chemokines in cancer invasion and metastasis. Herein, we showed that C-C motif chemokine ligand 2 (CCL2)- C-C motif chemokine receptor 4 (CCR4) signaling, but not the CCL2- C-C motif chemokine receptor 2 (CCR2) axis, induces the formation of the vav guanine nucleotide exchange factor 2 (Vav2)- Rac family small GTPase 1 (Rac1) complex to activate the phosphorylation of myosin light chain (MLC), which is involved in the regulation of cell motility and cancer metastasis. We identified that targeting CCR4 could effectively interrupt the activation of HNSCC invasion and metastasis induced by CCL2 without the promoting cancer relapse observed during the subsequent withdrawal period. All current findings suggested that CCL2-CCR4-Vav2-Rac1-p-MLC signaling plays an essential role in cell migration and cancer metastasis of HNSCC, and CCR4 may serve as a new potential molecular target for HNSCC therapy.

Dynamic interplay of two molecular switches enabled by the MEK1/2–ERK1/2 and IL-6–STAT3 signaling axes controls epithelial cell migration in response to growth factors

Cell migration is an essential physiological process, and aberrant migration of epithelial cells underlies many pathological conditions. However, the molecular mechanisms governing cell migration are not fully understood. We report here that growth factor–induced epithelial cell migration is critically dependent on the crosstalk of two molecular switches, namely phosphorylation switch (P-switch) and transcriptional switch (T-switch). P-switch refers to dynamic interactions of deleted in liver cancer 1 (DLC1) and PI3K with tensin-3 (TNS3), phosphatase and tensin homolog (PTEN), C-terminal tension, and vav guanine nucleotide exchange factor 2 (VAV2) that are dictated by mitogen-activated protein kinase kinase 1/2–extracellular signal–regulated protein kinase 1/2–dependent phosphorylation of TNS3, PTEN, and VAV2. Phosphorylation of TNS3 and PTEN on specific Thr residues led to the switch of DLC1–TNS3 and PI3K–PTEN complexes to DLC1–PTEN and PI3K–TNS3 complexes, whereas Ser phosphorylation of VAV2 promotes the transition of the PI3K–TNS3/PTEN complexes to PI3K–VAV2 complex. T-switch denotes an increase in C-terminal tension transcription/expression regulated by both extracellular signal–regulated protein kinase 1/2 and signal transducer and activator of transcription 3 (STAT3) via interleukin-6–Janus kinase–STAT3 signaling pathway. We have found that, the P-switch is indispensable for both the initiation and continuation of cell migration induced by growth factors, whereas the T-switch is only required to sustain cell migration. The interplay of the two switches facilitated by the interleukin-6–Janus kinase–STAT3 pathway governs a sequence of dynamic protein–protein interactions for sustained cell migration. That a similar mechanism is employed by both normal and tumorigenic epithelial cells to drive their respective migration suggests that the P-switch and T-switch are general regulators of epithelial cell migration and potential therapeutic targets.

The underlying mechanisms of FGF2 on carotid atherosclerotic plaque development revealed by bioinformatics analysis

IntroductionThe purpose of this study was to explore the regulatory mechanisms of FGF2 on carotid atherosclerotic plaque development using bioinformatics analysis.Material and methodsExpression profiles of 32 atheroma plaque (AP) and 32 paired distant macroscopically intact (DMI) tissues samples in GSE43292 dataset were downloaded from the Gene Expression Omnibus database. Following identification of differential expression genes (DEGs), correlation analysis of fibroblast growth factor 2 (FGF2) and DEGs was conducted. Subsequently, functional enrichment analysis and protein-protein interaction network for FGF2 significantly correlated DEGs were constructed. Then, microRNAs (miRNAs) that regulated FGF2 and regulatory pairs of long noncoding RNA (lncRNA)-miRNA were predicted to construct lncRNA-miRNA-FGF2 network.ResultsA total of 101 DEGs between AP and DMI samples were identified, and 31 DEGs were analyzed to have coexpression relationships with FGF2, including 23 positively correlated and 8 negatively correlated DEGs. VAV3 had the lowest r value among all FGF2 negatively correlated DEGs. FGF2 positively correlated DEGs was closely related to “regulation of smooth muscle contraction” [eg., Calponin 1 (CNN1)], while FGF2 negatively correlated DEGs was significantly associated with “platelet activation” [eg., Vav Guanine Nucleotide Exchange Factor 3 (VAV3)]. In addition, totally 12 miRNAs that regulated FGF2 were predicted, and hsa-miR-15a-5p and hsa-miR-16-5p were highlighted in lncRNA-miRNA-FGF2 regulatory network.ConclusionsCNN1 might cooperate with FGF2 to regulate smooth muscle contractility during CAP formation. VAV3 might cooperate with FGF2 to be responsible for the development of CAP through participating in platelet activation. Hsa-miR-15a-5p and hsa-miR-16-5p might participate in the development of CAP via regulating FGF2.

Characterization of Rac/Cdc42 Inhibitors as Anti‐cancer Compounds

Metastatic breast cancer continues to be the primary cause of cancer-related death in women, needing targeted therapies to inhibit this process. Therefore, we are designing small molecule inhibitors to specifically block the metastatic phase, focusing on the Rho GTPases Rac1 and Cdc42. These close homologs direct the actin cytoskeletal changes required for cell migration/invasion, driving the first steps of metastasis. Rho GTPases are activated by Guanine Nucleotide Exchange Factors (GEF), which promote the exchange of GDP to GTP. We have designed the molecule Ehop-016, a carbazole derivative, to inhibit Rac1 at an IC50 of 1.1 uM by disrupting the interaction of the GEF Vav2 with Rac1. Based on this molecule, we designed a more potent inhibitor, MBQ-167, to block both Rac1 and Cdc42 at IC50s 103 nM and 78 nM, respectively,in human HER2 (+) breast cancer cells and triple-negative breast cancer cells. Moreover, MBQ-167 inhibits tumor growth and metastasis by ~90% in pre-clinical mouse models of breast cancer. MBQ-167 also has a different mechanism of inhibition to EHop-016 by direct inhibition of GTP/GDP binding. We hypothesized that by designing stronger inhibitors based on MBQ-167 structure with drug-like properties, we could achieve an improved inhibition for Rac1 and Cdc42, as well as achieve different specificities against the numerous oncogenic GEFs that regulate cancer malignancy. Thus, we synthesized a panel of derivatives, maintaining 9-ethyl-3-(1H-1,2,3-triazol-1-yl)-9H-carbazole as the core for each derivative. HER2 (+) breast cancer cells were treated with 500 nM of the derivatives for 72 hrs. The CellTiter 96 Non-Radioactive Cell Proliferation Assay was used to analyze cell viability by quantifying both attached and detached cells in the same well. Results show that MBQ-167 derivatives decreased cell viability to various degrees. Therefore, we have demonstrated that small structural modifications of MBQ-167 can affect the cytotoxic activity of carbazole derivatives with potential as anti-cancer drugs, and as tools to block Rac/Cdc42 activities in biological systems.

Estrogen Decreases Cytoskeletal Organization by Forming an ERα/SHP2/c-Src Complex in Osteoclasts to Protect against Ovariectomy-Induced Bone Loss in Mice.

Loss of ovarian function is closely related to estrogen (E2) deficiency, which is responsible for increased osteoclast (OC) differentiation and activity. We aimed to investigate the action mechanism of E2 to decrease bone resorption in OCs to protect from ovariectomy (OVX)-induced bone loss in mice. In vivo, tartrate-resistant acid phosphatase (TRAP) staining in femur and serum carboxy-terminal collagen crosslinks-1 (CTX-1) were analyzed upon E2 injection after OVX in mice. In vitro, OCs were analyzed by TRAP staining, actin ring formation, carboxymethylation, determination of reactive oxygen species (ROS) level, and immunoprecipitation coupled with Western blot. In vivo and in vitro, E2 decreased OC size more dramatically than OC number and Methyl-piperidino-pyrazole hydrate dihydrochloride (MPPD), an estrogen receptor alpha (ERα) antagonist, augmented the OC size. ERα was found in plasma membranes and E2/ERα signaling affected receptor activator of nuclear factor κB ligand (RANKL)-induced actin ring formation by rapidly decreasing a proto-oncogene tyrosine-protein kinase, cellular sarcoma (c-Src) (Y416) phosphorylation in OCs. E2 exposure decreased physical interactions between NADPH oxidase 1 (NOX1) and the oxidized form of c-Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), leading to higher levels of reduced SHP2. ERα formed a complex with the reduced form of SHP2 and c-Src to decrease c-Src activation upon E2 exposure, which blocked a signal for actin ring formation by decreased Vav guanine nucleotide exchange factor 3 (Vav3) (p–Y) and Ras-related C3 botulinum toxin substrate 1 (Rac1) (GTP) activation in OCs. E2/ERα signals consistently inhibited bone resorption in vitro. In conclusion, our study suggests that E2-binding to ERα forms a complex with SHP2/c-Src to attenuate c-Src activation that was induced upon RANKL stimulation in a non-genomic manner, resulting in an impaired actin ring formation and reducing bone resorption.

RETRACTED ARTICLE: GAS5 knockdown alleviates spinal cord injury by reducing VAV1 expression via RNA binding protein CELF2

Long non-coding RNA growth arrest specific transcript 5 (GAS5) has been found to be implicated in the pathogenesis of central nervous diseases and to be a contributor to hypoxic brain injury. However, the roles and molecular mechanisms of GAS5 in spinal cord injury (SCI) have not thoroughly investigated. Here, we reported that GAS5 knockdown improved rat locomotor function and alleviated pathological damage of spinal cord tissues by reducing oxidative stress, caspase-3 activity and vav guanine nucleotide exchange factor 1 (VAV1) expression in SCI rat models. GAS5 knockdown inhibited the increase of malondialdehyde (MDA) level and cell apoptotic rate induced by oxygen–glucose deprivation (OGD) and weakened the inhibitory effects of OGD on superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and cell viability in RN-Sc cells, suggesting that GAS5 loss mitigated OGD-triggered oxidative stress and cell injury in RN-Sc cells. Molecular mechanism explorations revealed that GAS5 recruited CUGBP, Elav-like family member 2 (CELF2) to the coding region of VAV1 mRNA, resulting in the increase of VAV1 mRNA stability and expression levels. VAV1 knockdown weakened OGD-induced oxidative stress and cell injury in RN-Sc cells. VAV1 loss alleviated GAS5-induced oxidative stress and cell injury in OGD-treated RN-Sc cells. As a conclusion, our findings suggested that GAS5 aggravated SCI by increasing VAV1 expression via binding with CELF2, deepening our understanding on function and molecular basis of GAS5 in SCI.

VAV1 mutations contribute to development of T-cell neoplasms in mice

AbstractActivating mutations in the Vav guanine nucleotide exchange factor 1 (VAV1) gene are reported in various subtypes of mature T-cell neoplasms (TCNs). However, oncogenic activities associated with VAV1 mutations in TCNs remain unclear. To define them, we established transgenic mice expressing VAV1 mutants cloned from human TCNs. Although we observed no tumors in these mice for up to a year, tumors did develop in comparably aged mice on a p53-null background (p53−/−VAV1-Tg), and p53−/−VAV1-Tg mice died with shorter latencies than did p53-null (p53−/−) mice. Notably, various TCNs with tendency of maturation developed in p53−/−VAV1-Tg mice, whereas p53−/− mice exhibited only immature TCNs. Mature TCNs in p53−/−VAV1-Tg mice mimicked a subtype of human peripheral T-cell lymphoma (PTCL-GATA3) and exhibited features of type 2 T helper (Th2) cells. Phenotypes seen following transplantation of either p53−/−VAV1 or p53−/− tumor cells into nude mice were comparable, indicating cell-autonomous tumor-initiating capacity. Whole-transcriptome analysis showed enrichment of multiple Myc-related pathways in TCNs from p53−/−VAV1-Tg mice relative to p53−/− or wild-type T cells. Remarkably, amplification of the Myc locus was found recurrently in TCNs of p53−/−VAV1-Tg mice. Finally, treatment of nude mice transplanted with p53−/−VAV1-Tg tumor cells with JQ1, a bromodomain inhibitor that targets the Myc pathway, prolonged survival of mice. We conclude that VAV1 mutations function in malignant transformation of T cells in vivo and that VAV1-mutant–expressing mice could provide an efficient tool for screening new therapeutic targets in TCNs harboring these mutations.