Project description:Cells treated with a specific antibody against α5β1 integrin exhibited cell spreading and scattering, over-expression of liver stem/progenitor cell markers and activation of the ERK1/2 and p38 MAPKs signaling cascades, in a similar manner to the process triggered by HGF/SF1 stimulation. Gene expression profiling revealed marked transcriptional changes of genes involved in cell adhesion and migration, as well as genes encoding chromatin remodeling factors. These responses were accompanied by conspicuous spatial reorganization of centromeres, while integrin genes conserved their spatial positioning in the interphase nucleus. Untreated cells versus HGF/SF1 treated or α5β1 integrin-mediated cell migration
Project description:Soluble VEGFR-1 (sVEGFR-1) acts both as a decoy receptor for VEGFs and as an extracellular matrix protein for α5β1 integrin. A sVEGFR-1-derived peptide that interacts with α5β1 integrin promotes angiogenesis. However, canonical signal downstream integrin activation is not induced, resulting into lack of focal adhesion maturation. We performed a gene expression profile of endothelial cells adhering on sVEGFR-1 compared to that of cells adhering on fibronectin, the principal α5β1 integrin ligand. Three protein kinase-C substrates, adducin, MARCKS, and radixin were differently modulated. Adducin and MARCKS were less phosphorylated whereas radixin was higher phosphorylated in sVEGFR-1 adhering cells, the latter leading to prolonged small GTPase Rac1 activation and induction of a pathway involving the heterotrimeric G protein α13. Altogether, our data indicated endothelial cell acquisition of an highly motile phenotype when adherent on sVEGFR-1. Finally, we indicated radixin as accountable for the angiogenic effect of α5β1 integrin interaction with sVEGFR-1 that in turn depends on an active VEGF-A/VEGFR-2 signaling.
Project description:Primary tumor growth and metastasis in triple-negative breast cancer (TNBC) require supporting vasculature, which develop through a combination of endothelial angiogenesis and vasculogenic mimicry (VM), a process associated with aggressive metastatic behavior in which vascular-like structures are lined by tumor cells. We developed αEGFR-E-P125A, an antibody-endostatin fusion protein that delivers a dimeric, mutant endostatin (E-P125A) payload that inhibits TNBC angiogenesis and VM in vitro and in vivo. To characterize the mechanisms associated with induction and inhibition of VM, RNA-seq of MDA-MB-231-4175 TNBC cells grown in a monolayer (2D) was compared to cells plated on Matrigel undergoing VM (3D). We then compared RNA-seq between TNBC cells in 3D and cells in 3D with VM inhibited by αEGFR-E-P125A (αEGFR-E-P125A). Gene set enrichment analysis (GSEA) demonstrated that VM induction activated the IL6-JAK-STAT3 and angiogenesis pathways, which were downregulated by αEGFR-E-P125A treatment. Correlative analysis of the phospho-proteome demonstrated decreased EGFR phosphorylation at Y1069, along with decreased phosphorylation of focal adhesion kinase (FAK) Y397 and STAT3 Y705 sites downstream of α5β1 integrin. Suppression of phosphorylation events downstream of EGFR and α5β1 integrin demonstrated that αEGFR-E-P125A interferes with ligand-receptor activation, inhibits VM, and overcomes oncogenic signaling associated with EGFR and α5β1 integrin crosstalk. In vivo, αEGFR-E-P125A treatment decreased primary tumor growth and VM, reduced lung metastasis, and confirmed the inhibition of signaling events observed in vitro. Simultaneous inhibition of EGFR and α5β1 integrin signaling by αEGFR-E-P125A is a promising strategy for the inhibition of VM, tumor growth, motility, and metastasis in TNBC and other EGFR-overexpressing tumors.
Project description:The airway epithelium of asthmatics is characterized by intrinsically abnormal wound repair that may contribute to disease pathobiology. In this study, we show that in asthma, the airway epithelial cells at the leading edge of a wound display aberrant migration patterns, reduced expression of α5 and β1 integrin subunits at baseline and during wound repair, resulting in dysregulated cell migration and an inability to fully repair. Transcriptional profiling identified the PI3K/Akt signaling pathway as the top upstream transcriptional regulator of integrin α5β1. Significantly, activation of Akt signaling enhanced airway epithelial repair in cultures derived from asthmatic children via upregulation of α5 and β1 integrin subunits. Conversely, inhibition of the PI3K/Akt signaling pathway in airway epithelial cultures from non-asthmatic children attenuated epithelial repair and reduced α5 and β1 integrin expression. Importantly, the FDA-approved drug celecoxib, and its non-COX2 inhibitory analogue dimethyl-celecoxib, also stimulated the PI3K/Akt/integrin α5β1 axis and restored airway epithelial repair in cells from asthmatics. Thus, targeting the PI3K/Akt pathway may represent a novel therapeutic avenue for asthma.
Project description:Integrin α5β1 and αv crosstalk in chemotaxis and clonogenic survival of prostate cancer cells is abrogated by a bispecific α5β1/αv antibody (BsAbα5β1/αv), which uniquely induces internalization and lysosomal degradation of target integrins. We hypothesized that the BsAbα5β1/αv inactivates pathological mechanosignaling pathways that correlate with integrin expression from patient samples. Mechanistic studies indicate that the BsAbα5β1/αv uniquely reverses YAP, beta-catenin and FAK nuclear localization compared to monospecific integrin α5β1 and αv antibody controls in basal-type androgen-receptor negative prostate cancer cells. Dual integrin αv and α5 knockdown alone phenocopied the BsAbα5β1/αv effect. Following BsAbα5β1/αv treatment, ATAC-seq studies indicated the chromatin accessibility to TEAD and AP-1 family members was markedly reduced. In vitro and in vivo RNA-seq indicated down-regulation of Myc/E2F, TGF-beta and epithelial mesenchymal transition (EMT) and upregulation of Type I and II interferon transcriptomic pathways. The BsAbα5β1/αv induced CXCL10 and CCL5 cytokine secretion, immune-infiltration of tumors, and natural-killer cell-mediated elimination of the basal-type prostate cancer xenografts in nude mice. αv integrin was highly expressed and principally correlated with the Myc signaling pathway in rapid autopsy tissue microarrays, consistent with correlative data from the SU2C metastatic castration-resistant prostate cancer and DKFZ early-onset prostate cancer cohorts. These studies connect integrin signaling with the central biology of basal-type and castration-resistant prostate cancer and define a novel therapeutic strategy that controls critical immunosuppressive pathways.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Integrin α5β1 mediates cell adhesion to the extracellular matrix (ECM) by binding fibronectin (Fn). Selectivity for Fn by α5β1 is achieved through recognition of an RGD motif in the 10th type-III Fn domain (Fn10) and the synergy site in the 9th type-III Fn domain (Fn9). However, details of the interaction dynamics are unknown. Here, we compared synergy-site and Fn-truncation mutations for their α5β1-binding affinities and stabilities. We also interrogated binding of the α5β1 ectodomain headpiece fragment to Fn using hydrogen deuterium exchange mass spectrometry (HDX MS) to probe binding sites and sites of integrin conformational change. Our results suggest the synergistic effect of Fn9 requires both specific residues and a folded domain. We found some residues considered important for synergy are required for stability. Additionally, we show decreases in fibronectin HDX are localized to a synergy peptide containing contacting residues in two β-strands, an intervening loop in Fn9, and the RGD-containing loop in Fn10, indicative of binding sites. We also identified binding sites in the α5-subunit β-propeller domain for the Fn9 synergy site and in the β1-subunit βI domain for Fn10 based on decreases in α5β1 HDX. Interestingly, the dominant effect of Fn binding was an increase in α5β1 deuterium exchange distributed over multiple sites that undergo changes in conformation or solvent accessibility and appear to be sites where energy is stored in the higher-energy, open-integrin conformation. Together, our results highlight regions important for α5β1 binding to Fn and dynamics associated with this interaction.
Project description:As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain.A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development.Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines.
Project description:PurposeWe investigated the evidence of recent positive selection in the human phototransduction system at single nucleotide polymorphism (SNP) and gene level.MethodsSNP genotyping data from the International HapMap Project for European, Eastern Asian, and African populations was used to discover differences in haplotype length and allele frequency between these populations. Numeric selection metrics were computed for each SNP and aggregated into gene-level metrics to measure evidence of recent positive selection. The level of recent positive selection in phototransduction genes was evaluated and compared to a set of genes shown previously to be under recent selection, and a set of highly conserved genes as positive and negative controls, respectively.ResultsSix of 20 phototransduction genes evaluated had gene-level selection metrics above the 90th percentile: RGS9, GNB1, RHO, PDE6G, GNAT1, and SLC24A1. The selection signal across these genes was found to be of similar magnitude to the positive control genes and much greater than the negative control genes.ConclusionsThere is evidence for selective pressure in the genes involved in retinal phototransduction, and traces of this selective pressure can be demonstrated using SNP-level and gene-level metrics of allelic variation. We hypothesize that the selective pressure on these genes was related to their role in low light vision and retinal adaptation to ambient light changes. Uncovering the underlying genetics of evolutionary adaptations in phototransduction not only allows greater understanding of vision and visual diseases, but also the development of patient-specific diagnostic and intervention strategies.