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- Angus-Dunne, Sarah J., et al.
(författare)
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Metallocene and organo-main group trifluoromethanesulfonates
- 2006
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Ingår i: Transition metal chemistry (Weinheim). - : Springer Science and Business Media LLC. - 0340-4285 .- 1572-901X. ; 31:2, s. 268-275
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Tidskriftsartikel (refereegranskat)abstract
- The substituted metallocene compounds Cp2M(OSO 2CF3)2 (Cp=η5-C 5H5; M = Ti, Zr, Hf, Nb, Mo), CpTi(OSO2CF 3)3 • 0.75(1,2-dimethoxyethane), and the organo-main group compounds (C6H5)3M′(OSO 2CF3) (M′=Si, Ge), (C6H5) 2Sn(OSO2CF3)2 and (C 6H5)3Sb(OSO2CF3) 2, were synthesized from the corresponding chloride or bromide compounds and silver trifluoromethanesulfonate (triflate) and characterized spectroscopically, including a detailed analysis of their IR spectra. Triflate coordination is typically monodentate, but CpTi(OSO2CF 3)3 • 0.75(1,2-dimethoxyethane) and the organo-germanium triflate show evidence of bidentate CF3SO 3 - ligands and are likely to have polymeric structures. Conductance measurements in nitromethane, acetone and acetonitrile have demonstrated the ease of triflate substitution, with a limited kinetic study of acetone solvation of the Ti and Hf compounds supporting an associative pathway. Three new catalysts for the polymerization of tetrahydrofuran, Cp 2HfCl2/Ag(OSO2CF3), CpTiCl 3/Ag(OSO2CF3) and (C6H 5)2SiCl2/Ag(OSO2CF3), are also reported.
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- Hansen, Christian, et al.
(författare)
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Phosphorylation of DARPP-32 regulates breast cancer cell migration downstream of the receptor tyrosine kinase DDR1.
- 2006
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 1090-2422 .- 0014-4827. ; 312:20, s. 4011-4018
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Tidskriftsartikel (refereegranskat)abstract
- Cell migration plays a central role in processes such as development, wound healing and cancer metastasis. Here we describe a novel interaction between DDR1, a receptor tyrosine kinase activated by collagen, and the phosphoprotein DARPP-32 in mammary epithelial cells. DARPP-32 expression was readily detected in non-transformed mammary cell lines, but was strongly reduced or even absent in breast tumor cell lines, such as MCF7. Transfection of MCF7 cells with DARPP-32 resulted in severely impaired cell migration, while DARPP-32 transfection into the DDR1-deficient breast cancer cell line MDA-MB-231 did not alter migration. Co-expression of both DDR1 and DARPP-32 in MDA-MB-231 cells inhibited migration, thereby supporting a critical role of the DDR1/DARPP-32 complex in motility. Mutational substitution of the phosphorylation sites Thr-34 or Thr-75 on DARPP-32 revealed that phosphorylation of Thr-34 is necessary for the ability of DARPP-32 to impair breast tumor cell migration. Thus, DARPP-32 signaling downstream of DDR1 is a potential new target for effective anti-metastatic breast cancer therapy.
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- Hansen, Christian, et al.
(författare)
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Wnt-5a-induced Phosphorylation of DARPP-32 Inhibits Breast Cancer Cell Migration in a CREB-dependent Manner
- 2009
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 284:40, s. 27533-27543
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Tidskriftsartikel (refereegranskat)abstract
- Tumor cell migration plays a central role in the process of cancer metastasis. We recently identified dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) as an antimigratory phosphoprotein in breast cancer cells. Here we link this effect of DARPP-32 to Wnt-5a signaling by demonstrating that recombinant Wnt-5a triggers cAMP elevation at the plasma membrane and Thr34-DARPP-32 phosphorylation in MCF-7 cells. In agreement, both protein kinase A (PKA) inhibitors and siRNA-mediated knockdown of Frizzled-3 receptor or G alpha(s) expression abolished Wnt-5a-induced phosphorylation of DARPP-32. Furthermore, Wnt-5a induced DARPP-32-dependent inhibition of MCF-7 cell migration. Phospho-Thr-34-DARPP-32 interacted with protein phosphatase-1 (PP1) and potentiated the Wnt-5a-mediated phosphorylation of CREB, a well-known PP1 substrate, but had no effect on CREB phosphorylation by itself. Moreover, inhibition of the Wnt-5a/DARPP-32/CREB pathway, by expression of dominant negative CREB (DN-CREB), diminished the antimigratory effect of Wnt-5a-induced phospho-Thr-34-DARPP-32. Phalloidin-staining revealed that that the presence of phospho-Thr-34-DARPP-32 in MCF-7 cells results in reduced filopodia formation. In accordance, the activity of the Rho GTPase Cdc42, known to be crucial for filopodia formation, was reduced in MCF-7 cells expressing phospho-Thr-34-DARPP- 32. The effects of DARPP-32 on cell migration and filopodia formation could be reversed in T47D breast cancer cells that were depleted of their endogenous DARPP-32 by siRNA targeting. Consequently, Wnt-5a activates a Frizzled-3/G alpha(s)/cAMP/PKA signaling pathway that triggers a DARPP-32- and CREB-dependent antimigratory response in breast cancer cells, representing a novel mechanism whereby Wnt-5a can inhibit breast cancer cell migration.
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- Kröll, T., et al.
(författare)
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Transfer Reactions on Neutron-rich Nuclei at REX-ISOLDE
- 2009
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1165, s. 363-368 461
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Konferensbidrag (refereegranskat)abstract
- We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the "island of inversion". The (d,p)- and (t,p)-reactions in inverse kinematics on the neutron-rich isotope Mg-30, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The gamma-decay of excited states has been detected in coincidence by the MINIBALL array. First results for Mg-31 and from the search for the second, spherical, 0(+) state in Mg-32 are presented.
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- Scott, Lena, et al.
(författare)
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Allosteric changes of the NMDA receptor trap diffusible dopamine 1 receptors in spines
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:3, s. 762-767
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Tidskriftsartikel (refereegranskat)abstract
- The dopaminergic and glutamatergic systems interact to initiate and organize normal behavior, a communication that may be perturbed in many neuropsychiatric diseases, including schizophrenia. We show here that NMDA, by allosterically modifying NMDA receptors, can act as a scaffold to recruit laterally diffusing dopamine D1 receptors (D1R) to neuronal spines. Using organotypic culture from rat striatum transfected with D1R fused to a fluorescent protein, we show that the majority of dendritic D1R are in lateral diffusion and that their mobility is confined by interaction with NMDA receptors. Exposure to NMDA reduces the diffusion coefficient for D1R and causes an increase in the number of D1R-positive spines. Unexpectedly, the action of NMDA in potentiating D1R recruitment was independent of calcium flow via the NMDA receptor channel. Thus, a highly energy-efficient, diffusion-trap mechanism can account for intraneuronal interaction between the glutamatergic and dopaminergic systems and for regulation of the number of D1R-positive spines. This diffusion trap system represents a molecular mechanism for brain plasticity and offers a promising target for development of antipsychotic therapy
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- Steen, Robert O., et al.
(författare)
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The role of isomeric effects on the luminescence lifetimes and electrochemistry of oligothienyl-bridged dinuclear tris(2,2′-bipyridine) ruthenium(II) complexes
- 2008
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; :11, s. 1784-1794
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Tidskriftsartikel (refereegranskat)abstract
- The luminescence lifetimes (in CH 3CN at room temperature) and electrochemical potentials (in CH 3CN) of a range of mono- and bis(bidentate) 2,2′-bipyridine-capped oligothiophene-bridged Ru II complexes based on the 6-(2-thienyl)-2,2′-bipyridine and 4-(2-thienyl)-2,2′-bipyridine motifs have been measured. The redox potentials occurred in a very narrow range and showed only small shifts from that of [Ru(bpy) 3] 2+, which indicates that the inductive effects of the substituents on the 2,2′-bipyridine ligands are very similar across this series. In the complexes that incorporated a bithiophene moiety the oxidation of the bithienyl group occurred at higher potentials than the metal-centered Ru III/II oxidation. No or very weak interaction between the metal cores in the dinuclear complexes was observed. It was found that the luminescence lifetimes of the complexes where the attachment point of the oligothiophene bridge is in the 4-position of a 2,2′-bipyridine ligand were extended compared to [Ru(bpy) 3] 2+, whereas the luminescence was very short-lived (<30 ns) or completely quenched in the complexes where the oligothiophene bridge was attached in the 6-position. The difference in lifetimes is probably due to steric interactions between the thienyl bridge and the auxiliary bipyridyl ligands, resulting in disturbances in coordination symmetry of the metal core.
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- Valiente-Dobon, J. J., et al.
(författare)
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Lifetime Measurements of the Neutron-Rich N=30 Isotones Ca-50 and Sc-51: Orbital Dependence of Effective Charges in the fp Shell
- 2009
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Ingår i: Physical Review Letters. - 1079-7114. ; 102:24
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Tidskriftsartikel (refereegranskat)abstract
- The lifetimes of the first excited states of the N=30 isotones Ca-50 and Sc-51 have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f(7/2) shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus Ca-48, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.
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