| 1. |
- Koutsioumpa, Marina, et al.
(författare)
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Interplay between αvβ3 Integrin and Nucleolin Regulates Human Endothelial and Glioma Cell Migration
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:1, s. 343-354
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Tidskriftsartikel (refereegranskat)abstract
- The multifunctional protein nucleolin (NCL) is overexpressed on the surface of activated endothelial and tumor cells and mediates the stimulatory actions of several angiogenic growth factors, such as pleiotrophin (PTN). Because α(v)β(3) integrin is also required for PTN-induced cell migration, the aim of the present work was to study the interplay between NCL and α(v)β(3) by using biochemical, immunofluorescence, and proximity ligation assays in cells with genetically altered expression of the studied molecules. Interestingly, cell surface NCL localization was detected only in cells expressing α(v)β(3) and depended on the phosphorylation of β(3) at Tyr(773) through receptor protein-tyrosine phosphatase β/ζ (RPTPβ/ζ) and c-Src activation. Downstream of α(v)β(3,) PI3K activity mediated this phenomenon and cell surface NCL was found to interact with both α(v)β(3) and RPTPβ/ζ. Positive correlation of cell surface NCL and α(v)β(3) expression was also observed in human glioblastoma tissue arrays, and inhibition of cell migration by cell surface NCL antagonists was observed only in cells expressing α(v)β(3). Collectively, these data suggest that both expression and β(3) integrin phosphorylation at Tyr(773) determine the cell surface localization of NCL downstream of the RPTPβ/ζ/c-Src signaling cascade and can be used as a biomarker for the use of cell surface NCL antagonists as anticancer agents.
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| 2. |
- Lampropoulou, Evgenia, et al.
(författare)
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Cyclin-dependent kinase 5 mediates pleiotrophin-induced endothelial cell migration
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Pleiotrophin (PTN) stimulates endothelial cell migration through binding to receptor protein tyrosine phosphatase beta/zeta (RPTP beta/zeta) and alpha(nu)beta(3) integrin. Screening for proteins that interact with RPTP beta/zeta and potentially regulate PTN signaling, through mass spectrometry analysis, identified cyclindependent kinase 5 (CDK5) activator p35 among the proteins displaying high sequence coverage. Interaction of p35 with the serine/threonine kinase CDK5 leads to CDK5 activation, known to be implicated in cell migration. Protein immunoprecipitation and proximity ligation assays verified p35-RPTP beta/zeta interaction and revealed the molecular association of CDK5 and RPTP beta/zeta. In endothelial cells, PTN activates CDK5 in an RPTP beta/zeta- and phosphoinositide 3-kinase (PI3K)-dependent manner. On the other hand, c-Src, alpha(nu)beta(3) and ERK1/2 do not mediate the PTN-induced CDK5 activation. Pharmacological and genetic inhibition of CDK5 abolished PTN-induced endothelial cell migration, suggesting that CDK5 mediates PTN stimulatory effect. A new pyrrolo[2,3-alpha] carbazole derivative previously identified as a CDK1 inhibitor, was found to suppress CDK5 activity and eliminate PTN stimulatory effect on cell migration, warranting its further evaluation as a new CDK5 inhibitor. Collectively, our data reveal that CDK5 is activated by PTN, in an RPTP beta/zeta-dependent manner, regulates PTN-induced cell migration and is an attractive target for the inhibition of PTN pro-angiogenic properties.
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