Project description:Activation of the Wnt pathway is at the core of many human cancers. During canonical Wnt signaling, the Lrp6 and Frizzled receptors bind to the Wnt growth factor, which leads to the complex being endocytosed. Glycogen Synthase Kinase 3 (GSK3), Dishevelled (Dvl), and Axin are sequestered inside the intraluminal vesicles of late endosomes, known as multivesicular bodies (MVBs). Here we present experiments showing that Wnt causes the endocytosis of focal adhesion (FA) proteins and depletion of Integrin β 1 (ITGβ1) from the cell surface. FAs and integrins provide link the cytoskeleton to the extracellular matrix. Wnt-induced macropinocytosis of the plasma membrane caused ITGβ1 depletion and was accompanied by striking changes in the actin cytoskeleton. In situ protease protection assays in cultured cells showed that ITGβ1 was sequestered within membrane-bounded organelles that corresponded to Wnt-induced MVBs containing GSK3 and focal adhesion-associated proteins. An in vivo model using Xenopus embryos dorsalized by Wnt8 mRNA showed that ITGβ1 depletion decreased Wnt signaling. The cross-talk between Wnt signaling, membrane trafficking, and focal adhesions should be relevant to human cancer and cell biology.
Project description:The goal of this study was to identify transcripts, which are differentially regulatulated in the presence and absence of Focal Adhesion Kinase. As Focal Adhesion Kinase activity can depend upon cell density (Snijder et al. Nature 2009), biological replicates where cells, were seeded very sparsely or confluently, were used. Focal Adhesion Kinase Knockout (ATCC CRL-2644) and Rescue Cells (Sieg et al. 1998, clone DA2) were seeded at two different concentrations. Replicas refer to biological replicates, performed on different days. Only one single technical replicate has been done per biological replicate.
Project description:The goal of this study was to identify transcripts, which are differentially regulatulated in the presence and absence of Focal Adhesion Kinase. As Focal Adhesion Kinase activity can depend upon cell density (Snijder et al. Nature 2009), biological replicates where cells, were seeded very sparsely or confluently, were used.
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. Endothelial cells were let adhere in Petri dishes coated with fibronectin or sVEGFR-1 before RNA extraction and hybridization on Affymetrix microarrays. Endothelial cells plated on BSA-treated Petri dishes were used as non-adhesion control. Each hybridization was performed in triplicate.
Project description:Effect of a tumor promoter TPA on collagen IV based focal adhesions from CHO cells expressing human integrin alpha1 with activating mutation E317A
Project description:To explore the dynamics of integrin adhesion complex disassembly, isolated adhesion complexes from U2OS cells were subjected to mass spectrometry based proteomic analysis. U2OS cells were allowed to spread on FN, treated with nocodazole for 4 hours to disrupt microtubules. To coordinate microtubule-induced integrin adhesion complex disassembly nocodazole was subsequently washed out and adhesion complexes isolated at 5, 10 and 15 minutes during this process.
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:Integrins, the principal extracellular matrix (ECM) receptors of the cell, promote cell adhesion, migration, and proliferation, which are key events for cancer growth and metastasis. To date, most integrin-targeted cancer therapeutics have disrupted integrin-ECM interactions, which are viewed as critical for integrin functions. However, such agents have failed to improve cancer patient outcomes. We show that integrin b1, a highly expressed subunit in lung epithelium, is required for lung adenocarcinoma development in a carcinogen-induced mouse model. Likewise, human lung adenocarcinoma cell lines with integrin b1 deletion failed to form colonies in soft agar and tumors in mice. Mechanistically, we demonstrate that these effects do not require integrin b1-mediated adhesion to ECM but are dependent on integrin b1 cytoplasmic tail-mediated activation of focal adhesion kinase (FAK). Together, these studies support a critical role for integrin b1 in lung tumorigenesis that is mediated through constitutive, ECM-binding independent signaling involving the cytoplasmic tail.