scholarly journals The Junction-associated Protein AF-6 Interacts and Clusters with Specific Eph Receptor Tyrosine Kinases at Specialized Sites of Cell–Cell Contact in the Brain

1999 ◽  
Vol 144 (2) ◽  
pp. 361-371 ◽  
Author(s):  
Michael Buchert ◽  
Stefan Schneider ◽  
Virginia Meskenaite ◽  
Mark T. Adams ◽  
Eli Canaani ◽  
...  
Keyword(s):  
Rat Brain ◽  
Fluorescent Protein ◽  
Pdz Domain ◽  
Cell Junctions ◽  
Cell Contact ◽  
Physical Interaction ◽  
Eph Receptors ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Cell Cell

The AF-6/afadin protein, which contains a single PDZ domain, forms a peripheral component of cell membranes at specialized sites of cell–cell junctions. To identify potential receptor-binding targets of AF-6 we screened the PDZ domain of AF-6 against a range of COOH-terminal peptides selected from receptors having potential PDZ domain-binding termini. The PDZ domain of AF-6 interacts with a subset of members of the Eph subfamily of RTKs via its COOH terminus both in vitro and in vivo. Cotransfection of a green fluorescent protein-tagged AF-6 fusion protein with full-length Eph receptors into heterologous cells induces a clustering of the Eph receptors and AF-6 at sites of cell–cell contact. Immunohistochemical analysis in the adult rat brain reveals coclustering of AF-6 with Eph receptors at postsynaptic membrane sites of excitatory synapses in the hippocampus. Furthermore, AF-6 is a substrate for a subgroup of Eph receptors and phosphorylation of AF-6 is dependent on a functional kinase domain of the receptor. The physical interaction of endogenous AF-6 with Eph receptors is demonstrated by coimmunoprecipitation from whole rat brain lysates. AF-6 is a candidate for mediating the clustering of Eph receptors at postsynaptic specializations in the adult rat brain.

scholarly journals The Ras Target AF-6 Interacts with ZO-1 and Serves as a Peripheral Component of Tight Junctions in Epithelial Cells

1997 ◽  
Vol 139 (3) ◽  
pp. 785-795 ◽  
Author(s):  
Takaharu Yamamoto ◽  
Naozumi Harada ◽  
Kyoko Kano ◽  
Shin-ichiro Taya ◽  
Eli Canaani ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions ◽  
Adherens Junctions ◽  
Pdz Domain ◽  
Cell Junctions ◽  
Cell Contact ◽  
Fusion Partner ◽  
Cell Contacts ◽  
Contact Sites ◽  
Cell Cell

The dynamic rearrangement of cell–cell junctions such as tight junctions and adherens junctions is a critical step in various cellular processes, including establishment of epithelial cell polarity and developmental patterning. Tight junctions are mediated by molecules such as occludin and its associated ZO-1 and ZO-2, and adherens junctions are mediated by adhesion molecules such as cadherin and its associated catenins. The transformation of epithelial cells by activated Ras results in the perturbation of cell–cell contacts. We previously identified the ALL-1 fusion partner from chromosome 6 (AF-6) as a Ras target. AF-6 has the PDZ domain, which is thought to localize AF-6 at the specialized sites of plasma membranes such as cell–cell contact sites. We investigated roles of Ras and AF-6 in the regulation of cell–cell contacts and found that AF-6 accumulated at the cell–cell contact sites of polarized MDCKII epithelial cells and had a distribution similar to that of ZO-1 but somewhat different from those of catenins. Immunoelectron microscopy revealed a close association between AF-6 and ZO-1 at the tight junctions of MDCKII cells. Native and recombinant AF-6 interacted with ZO-1 in vitro. ZO-1 interacted with the Ras-binding domain of AF-6, and this interaction was inhibited by activated Ras. AF-6 accumulated with ZO-1 at the cell–cell contact sites in cells lacking tight junctions such as Rat1 fibroblasts and PC12 rat pheochromocytoma cells. The overexpression of activated Ras in Rat1 cells resulted in the perturbation of cell–cell contacts, followed by a decrease of the accumulation of AF-6 and ZO-1 at the cell surface. These results indicate that AF-6 serves as one of the peripheral components of tight junctions in epithelial cells and cell–cell adhesions in nonepithelial cells, and that AF-6 may participate in the regulation of cell–cell contacts, including tight junctions, via direct interaction with ZO-1 downstream of Ras.

scholarly journals Tyrosine-based Signals Regulate the assembly of Daple•PARD3 Complex at Cell-cell Junctions during Polarized Planar Cell Migration

2019 ◽  
Author(s):  
Jason Ear ◽  
Anokhi Saklecha ◽  
Navin Rajapakse ◽  
Julie Choi ◽  
Majid Ghassemian ◽  
...  
Keyword(s):  
Cell Migration ◽  
Tyrosine Kinases ◽  
Planar Cell Polarity ◽  
Pdz Domain ◽  
Cell Junctions ◽  
Cell Contact ◽  
Binding Motif ◽  
Planar Polarity ◽  
Gradient Sensing ◽  
Cell Cell

SummaryPolarized distribution of organelles and molecules inside a cell is vital for a range of cellular processes and its loss is frequently encountered in disease. Polarization during planar cell migration is a special condition in which cellular orientation is triggered by cell-cell contact. Here, we demonstrate that the multi-modular signaling scaffold Daple (CCDC88C) is a component of cell junctions in epithelial cells which serves like a cellular ‘compass’ for establishing and maintaining contact-triggered planar polarity via its interaction with the polarity regulator PARD3, which has been implicated in both apical-basal and planar polarity. This interaction, mediated by Daple’s PDZ-binding motif (PBM) and the third PDZ domain of PARD3, is fine-tuned by two tyrosine phosphoevents on Daple’s PBM that are known to be triggered by a multitude of receptor and non-receptor tyrosine kinases, such as Src. Hypophosphorylation strengthens the interaction, whereas hyperphosphorylation disrupts it. These findings reveal an unexpected role of Daple within the planar cell polarity pathway as a platform for signal integration and gradient sensing for tyrosine-based signals.

Expression of neurocan after transient middle cerebral artery occlusion in adult rat brain

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S217-S217
Author(s):  
Kentaro Deguchi ◽  
Mikiro Takaishi ◽  
Takeshi Hayashi ◽  
Atsuhiko Oohira ◽  
Shoko Nagotani ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Rat Brain ◽  
Middle Cerebral Artery Occlusion ◽  
Cerebral Artery ◽  
Artery Occlusion ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Cerebral Artery Occlusion

Development of Monoamine Oxidase and Aldehyde Dehydrogenase in Reaggregating Cultures of Fetal Rat Brain Cells

1989 ◽  
Vol 16 (3) ◽  
pp. 281-286
Author(s):  
Olof Tottmar ◽  
Maria Söderbäck ◽  
Anders Aspberg
Keyword(s):  
Monoamine Oxidase ◽  
Rat Brain ◽  
Aldehyde Dehydrogenase ◽  
Brain Cells ◽  
Mao B ◽  
Adult Rat ◽  
Fetal Rat ◽  
Adult Rat Brain ◽  
Mao A ◽  
Fetal Rat Brain

The development of monoamine oxidase (MAO) and aldehyde dehydrogenase (ALDH) in reaggregation cultures of fetal rat brain cells was compared with that of enzymatic markers for glial and neuronal cells. Only MAO-A was detected in the cultures during the first week, but, during the following three weeks, the activity of MAO-B increased more rapidly than that of MAO-A. The ratio MAO-A/MAO-B in four-week aggregates was close to that found in the adult rat brain. The activity of ALDH started to increase rapidly after 15 days, and the developmental pattern was intermediate to those of the glial and neuronal markers. The activity after four weeks was close to that found in the adult rat brain. Epidermal growth factor (EGF) caused a slight decrease in the activities of the low-Km ALDH (after four weeks) and the neuronal marker, choline acetyltransferase (after two weeks), whereas the other markers were not affected. By contrast, the activities of MAO-A and MAO-B were greatly increased during almost the entire culture period. It is suggested that this effect of EGF was the result of increased mitotic activity and/or biochemical differentiation of other cell types present in the cell aggregates, e.g. capillary endothelial cells.

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