| 1. |
- Looman, Camilla, et al.
(author)
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An activating mutation in the PDGF receptor-beta causes abnormal morphology in the mouse placenta
- 2007
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In: International Journal of Developmental Biology. - : UPV/EHU Press. - 0214-6282 .- 1696-3547. ; 51:5, s. 361-370
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Journal article (peer-reviewed)abstract
- An oncogenic D842V mutation in the platelet-derived growth factor (PDGF) alpha-receptor (Pdgfra) has recently been described in patients with gastrointestinal stromal tumors. In order to test if the same mutation would confer oncogenic properties to the homologous PDGF beta-receptor (Pdgfrb), the corresponding aspartic acid residue at position 849 of Pdgfrb was changed into valine (D849V) using a knock-in strategy. This mutation turned out to be dominantly lethal and caused death even in chimeras (from 345 transferred chimeric blastocysts, no living coat chimeras were detected). Experiments employing mouse embryonic fibroblasts (MEFs) indicated hyperactivity of the mutant receptor. The mutant receptor was phosphorylated in a ligand-independent manner and, in contrast to wild-type MEFs, mutant cells proliferated even in the absence of ligand. Knockout experiments have previously indicated a role for Pdgfrb in placental development. We therefore analyzed wild-type and Pdgfrb D849V chimeric placentas from different gestational stages. No differences were detected at embryonic days 11.5 and 13.5 (n=4). At embryonic day 17.5, however, chimeric placentas (n=3/4) displayed abnormalities both in the labyrinth and in the chorionic plate. The changes included hyper-proliferation of alpha-smooth muscle actin and platelet/endothelial cell adhesion molecule-1 positive cells in the labyrinth and cells in the chorionic plate. In addition, the fetal blood vessel compartment of the labyrinth was completely disorganized.
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| 2. |
- Pinidiyaarachchi, Amalka, et al.
(author)
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A detailed analysis of 3D subcellular signal localization
- 2009
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In: Cytometry Part A. - : Wiley. - 1552-4922 .- 1552-4930. ; 75A:4, s. 319-328
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Journal article (peer-reviewed)abstract
- Detection and localization of fluorescent signals in relation to other subcellular structures is an important task in various biological studies. Many methods for analysis of fluorescence microscopy image data are limited to 2D. As cells are in fact 3D structures, there is a growing need for robust methods for analysis of 3D data. This article presents an approach for detecting point-like fluorescent signals and analyzing their subnuclear position. Cell nuclei are delineated using marker-controlled (seeded) 3D watershed segmentation. User-defined object and background seeds are given as input, and gradient information defines merging and splitting criteria. Point-like signals are detected using a modified stable wave detector and localized in relation to the nuclear membrane using distance shells. The method was applied to a set of biological data studying the localization of Smad2-Smad4 protein complexes in relation to the nuclear membrane. Smad complexes appear as early as 1 min after stimulation while the highest signal concentration is observed 45 min after stimulation, followed by a concentration decrease. The robust 3D signal detection and concentration measures obtained using the proposed method agree with previous observations while also revealing new information regarding the complex formation.
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| 3. |
- Wang, Xiaolu, et al.
(author)
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A protein interaction node at the neurotransmitter release site : domains of Aczonin/Piccolo, Bassoon, CAST, and rim converge on the N-terminal domain of Munc13-1
- 2009
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In: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 29:40, s. 12584-12596
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Journal article (peer-reviewed)abstract
- Multidomain scaffolding proteins organize the molecular machinery of neurotransmitter vesicle dynamics during synaptogenesis and synaptic activity. We find that domains of five active zone proteins converge on an interaction node that centers on the N-terminal region of Munc13-1 and includes the zinc-finger domain of Rim1, the C-terminal region of Bassoon, a segment of CAST1/ELKS2, and the third coiled-coil domain (CC3) of either Aczonin/Piccolo or Bassoon. This multidomain complex may constitute a center for the physical and functional integration of the protein machinery at the active zone. An additional connection between Aczonin and Bassoon is mediated by the second coiled-coil domain of Aczonin. Recombinant Aczonin-CC3, expressed in cultured neurons as a green fluorescent protein fusion protein, is targeted to synapses and suppresses vesicle turnover, suggesting involvements in synaptic assembly as well as activity. Our findings show that Aczonin, Bassoon, CAST1, Munc13, and Rim are closely and multiply interconnected, they indicate that Aczonin-CC3 can actively participate in neurotransmitter vesicle dynamics, and they highlight the N-terminal region of Munc13-1 as a hub of protein interactions by adding three new binding partners to its mechanistic potential in the control of synaptic vesicle priming.
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