47 research outputs found
Extracellular signal-regulated kinase promotes Rho-dependent focal adhesion formation by suppressing p190A
No full textCell migration is critical for normal development and for pathological processes including cancer cell metastasis. Dynamic remodeling of focal adhesions and the actin cytoskeleton are crucial determinants of cell motility. The Rho family and the mitogen-activated protein kinase (MAPK) module consisting of MEK– extracellular signal-regulated kinase (ERK) are important regulators of these processes, but mechanisms for the integration of these signals during spreading and motility are incompletely understood. Here we show that ERK activity is required for fibronectin-stimulated Rho-GTP loading, Rho-kinase function, and the maturation of focal adhesions in spreading cells. We identify p190A RhoGAP as a major target for ERK signaling in adhesion assembly and identify roles for ERK phosphorylation of the C terminus in p190A localization and activity. These observations reveal a novel role for ERK signaling in adhesion assembly in addition to its established role in adhesion disassembly. Cell migration is a highly coordinated process essential for physiological and pathological processes (69). Signaling through Rho family GTPases (e.g., Rac, Cdc42, and Rho) is crucial for cell migration. Activated Rac and Cdc42 are involved in the production of a dominant lamellipodium and filopodia, respec
Molecular Determinants of the Human a 2C -Adrenergic Receptor Temperature-Sensitive Intracellular Traffic s
No full textABSTRACT The human a 2C -adrenergic receptor (a 2C -AR) is localized intracellularly at physiologic temperature. Decreasing the environmental temperature strongly stimulates the receptor transport to the cell surface. In contrast, rat and mouse a 2C -AR plasma membrane levels are less sensitive to decrease in temperature, whereas the opossum a 2C -AR cell surface levels are not changed in these conditions. Structural analysis demonstrated that human a 2C -AR has a high number of arginine residues in the third intracellular loop and in the C-terminus, organized as putative RXR motifs. Although these motifs do not affect the receptor subcellular localization at 37°C, deletion of the arginine clusters significantly enhanced receptor plasma membrane levels at reduced temperature. We found that this exaggerated transport of the human receptor is mediated by two functional arginine clusters, one in the third intracellular loop and one in the C-terminus. This effect is mediated by interactions with COPI vesicles, but not by 14-3-3 proteins. In rat a 2C -AR, the arginine cluster from the third intracellular loop is shifted to the left due to three missing residues. Reinsertion of these residues in the rat a 2C -AR restored the same temperature sensitivity as in the human receptor. Proteomic and coimmunoprecipitation experiments identified pontin as a molecule having stronger interactions with human a 2C -AR compared with rat a 2C -AR. Inhibition of pontin activity enhanced human receptor plasma membrane levels and signaling at 37°C. Our results demonstrate that human a 2C -AR has a unique temperature-sensitive traffic pattern within the G protein-coupled receptor class due to interactions with different molecular chaperones, mediated in part by strict spatial localization of specific arginine residues
Differential requirement for MEK Partner 1 in DU145 prostate cancer cell migration
No full textAbstract ERK signaling regulates focal adhesion disassembly during cell movement, and increased ERK signaling frequently contributes to enhanced motility of human tumor cells. We previously found that the ERK scaffold MEK Partner 1 (MP1) is required for focal adhesion disassembly in fibroblasts. Here we test the hypothesis that MP1-dependent ERK signaling regulates motility of DU145 prostate cancer cells. We find that MP1 is required for motility on fibronectin, but not for motility stimulated by serum or EGF. Surprisingly, MP1 appears not to function through its known binding partners MEK1 or PAK1, suggesting the existence of a novel pathway by which MP1 can regulate motility on fibronectin. MP1 may function by regulating the stability or expression of paxillin, a key regulator of motility.</p
Additional file 2 of Conservation of immune gene signatures in solid tumors and prognostic implications
No full textConsensus clustering summary of SOM algorithm. This Excel file contains summary of the SOM consensus clustering results as produced by ConsensusClustering GenePattern module [26, 27]. Each cancer dataset (breast, colon, lung ovarian and prostate) has two tabs. One tab displays images of the summary statistics. The other tab lists the number of clusters selected for our analysis and contains Affy ID, gene symbol and title. (XLSX 5007 kb
Additional file 4 of Conservation of immune gene signatures in solid tumors and prognostic implications
No full textUnivariate survival analysis. This Excel file contains all results of univariate survival analysis. (XLSX 159 kb
Additional file 3 of Conservation of immune gene signatures in solid tumors and prognostic implications
No full textCombined meta-intersections between two algorithms SOM and k-means. This Excel file contains final 23 meta-intersections as described in Results section. Each intersection is in separate tab, which also contains gene-annotation enrichment analysis results. (XLSX 721 kb
Epidermal Growth Factor Stimulates Extracellular-Signal Regulated Kinase Phosphorylation of a Novel Site on Cytoplasmic Dynein Intermediate Chain 2
No full textExtracellular-signal regulated kinase (ERK) signaling is required for a multitude of physiological and patho-physiological processes. However, the identities of the proteins that ERK phosphorylates to elicit these responses are incompletely known. Using an affinity purification methodology of general utility, here we identify cytoplasmic dynein intermediate chain 2 (DYNC1I-2, IC-2) as a novel substrate for ERK following epidermal growth factor receptor stimulation of fibroblasts. IC-2 is a subunit of cytoplasmic dynein, a minus-end directed motor protein necessary for transport of diverse cargos along microtubules. Emerging data support the hypothesis that post-translational modification regulates dynein but the signaling mechanisms used are currently unknown. We find that ERK phosphorylates IC-2 on a novel, highly conserved Serine residue proximal to the binding site for the p150Glued subunit of the cargo adapter dynactin. Surprisingly, neither constitutive phosphorylation nor a phosphomimetic substitution of this Serine influences binding of p150Glued to IC-2. These data suggest that ERK phosphorylation of IC-2 regulates dynein function through mechanisms other than its interaction with dynactin
Prosaposin down-modulation decreases metastatic prostate cancer cell adhesion, migration, and invasion
No full textAbstract Background Factors responsible for invasive and metastatic progression of prostate cancer (PCa) remain largely unknown. Previously, we reported cloning of prosaposin (PSAP) and its genomic amplification and/or overexpression in several androgen-independent metastatic PCa cell lines and lymph node metastases. PSAP is the lysosomal precursor of saposins, which serve as activators for lysosomal hydrolases involved in the degradation of ceramide (Cer) and other sphingolipids. Results Our current data show that, in metastatic PCa cells, stable down-modulation of PSAP by RNA-interference via a lysosomal proteolysis-dependent pathway decreased β1A-integrin expression, its cell-surface clustering, and adhesion to basement membrane proteins; led to disassembly of focal adhesion complex; and decreased phosphorylative activity of focal adhesion kinase and its downstream adaptor molecule, paxillin. Cathepsin D (CathD) expression and proteolytic activity, migration, and invasion were also significantly decreased in PSAP knock-down cells. Transient-transfection studies with β1A integrin- or CathD-siRNA oligos confirmed the cause and effect relationship between PSAP and CathD or PSAP and Cer-β1A integrin, regulating PCa cell migration and invasion. Conclusion Our findings suggest that by a coordinated regulation of Cer levels, CathD and β1A-integrin expression, and attenuation of "inside-out" integrin-signaling pathway, PSAP is involved in PCa invasion and therefore might be used as a molecular target for PCa therapy.</p
