13 results found
Brezovjakova H, Tomlinson C, Mohd Naim N, et al., 2019, Junction Mapper is a novel computer vision tool to decipher cell-cell contact phenotypes., eLife, Vol: 8, Pages: 1-48, ISSN: 2050-084X
Stable cell-cell contacts underpin tissue architecture and organization. Quantification of junctions of mammalian epithelia requires laborious manual measurements that are a major roadblock for mechanistic studies. We designed Junction Mapper as an open access, semi-automated software that defines the status of adhesiveness via the simultaneous measurement of pre-defined parameters at cell-cell contacts. It identifies contacting interfaces and corners with minimal user input and quantifies length, area and intensity of junction markers. Its ability to measure fragmented junctions is unique. Importantly, junctions that considerably deviate from the contiguous staining and straight contact phenotype seen in epithelia are also successfully quantified (i.e. cardiomyocytes or endothelia). Distinct phenotypes of junction disruption can be clearly differentiated among various oncogenes, depletion of actin regulators or stimulation with other agents. Junction Mapper is thus a powerful, unbiased and highly applicable software for profiling cell-cell adhesion phenotypes and facilitate studies on junction dynamics in health and disease.
Erasmus JC, Bruche S, Pizarro L, et al., 2017, Corrigendum: Defining functional interactions during biogenesis of epithelial junctions, Nature Communications, Vol: 8, Pages: 14195-14195, ISSN: 2041-1723
The original version of this Article (https://doi.org/10.1038/ncomms13542) contained an error in the spelling of the author Tommaso Poggioli, which was incorrectly given as Tommaso Pogglioli. This has now been corrected in both the PDF and HTML versions of the Article.
Braga VMM, 2016, Defining functional interactions during biogenesis of epithelial junctions, Nature Communications, Vol: 7, Pages: 1-17, ISSN: 2041-1723
In spite of extensive recent progress, a comprehensive understanding of how actin cytoskeleton remodelling supports stable junctions remains to be established. Here we design a platform that integrates actin functions with optimized phenotypic clustering and identify new cytoskeletal proteins, their functional hierarchy and pathways that modulate E-cadherin adhesion. Depletion of EEF1A, an actin bundling protein, increases E-cadherin levels at junctions without a corresponding reinforcement of cell-cell contacts. This unexpected result reflects a more dynamic and mobile junctional actin in EEF1A-depleted cells. A partner for EEF1A in cadherin contact maintenance is the formin DIAPH2, which interacts with EEF1A. In contrast, depletion of either the endocytic regulator TRIP10 or the Rho GTPase activator VAV2 reduces E-cadherin levels at junctions. TRIP10 binds to and requires VAV2 function for its junctional localization. Overall, we present new conceptual insights on junction stabilization, which integrate known and novel pathways with impact for epithelial morphogenesis, homeostasis and diseases.
Braga VMM, Erasmus JE, Welsh N, 2015, Cooperation of distinct Rac-dependent pathways to stabilize E-cadherin adhesion, Cellular Signalling, Vol: 27, ISSN: 1873-3913
Erasmus JC, Welsh NJ, Braga VMM, 2015, Cooperation of distinct Rac-dependent pathways to stabilise E-cadherin adhesion, Cellular Signalling, Vol: 27, Pages: 1905-1913, ISSN: 1873-3913
The precise mechanisms via which Rac1 is activated by cadherin junctions are not fully known. In keratinocytesRac1 activation by cadherin junctions requires EGFR signalling, but how EGFR does so is unclear. To addresswhich activator could mediate E-cadherin signalling to Rac1, we investigated EGFR and two Rac1 GEFs, SOS1and DOCK180. EGFR RNAi prevented junction-induced Rac1 activation and led to fragmented localization ofE-cadherin at cadherin contacts. In contrast, depletion of another EGFR family member, ErbB3, did not interferewith either process. DOCK180 RNAi, but not SOS1, prevented E-cadherin-induced Rac1 activation. However, in astrong divergence from EGFR RNAi phenotype, DOCK180 depletion did not perturb actin recruitment orcadherin localisation at junctions. Rather, reduced DOCK180 levels impaired the resistance to mechanicalstress of pre-formed cell aggregates. Thus, within the same cell type, EGFR and DOCK180 regulate Rac1activation by newly-formed contacts, but control separate cellular events that cooperate to stabilisejunctions
Kalaji R, Wheeler AP, Erasmus JC, et al., 2012, ROCK1 and ROCK2 regulate epithelial polarisation and geometric cell shape, BIOLOGY OF THE CELL, Vol: 104, Pages: 435-451, ISSN: 0248-4900
Nola S, Erasmus JC, Braga VM, 2012, Quantitative and robust assay to measure cell-cell contact assembly and maintenance, Vol: 827, Pages: 143-155, ISSN: 1940-6029
Epithelial junction formation and maintenance are multistep processes that rely on the clustering of macromolecular complexes. These events are highly regulated by signalling pathways that involve Rho small GTPases. Usually, when analysing the contribution of different components of Rho-dependent pathways to cell-cell adhesion, the localisation of adhesion receptors at junctions is evaluated by immunofluorescence. However, we find that this method has limitations on the quantification (dynamic range), ability to detect partial phenotypes and to differentiate between the participation of a given regulatory protein in assembly and/or maintenance of cell-cell contacts.In this chapter, we describe a suitable method, the aggregation assay, in which we adapted a quantitative strategy to allow objective and reproducible detection of partial phenotypes. Importantly, this methodology estimates the ability of cells to form junctions and their resistance to mechanical shearing forces (stabilisation).
Erasmus J, Aresta S, Nola S, et al., 2010, Newly formed E-cadherin contacts do not activate Cdc42 or induce filopodia protrusion in human keratinocytes, BIOLOGY OF THE CELL, Vol: 102, Pages: 13-24, ISSN: 0248-4900
Liebig T, Erasmus J, Kalaji R, et al., 2009, RhoE Is Required for Keratinocyte Differentiation and Stratification, MOLECULAR BIOLOGY OF THE CELL, Vol: 20, Pages: 452-463, ISSN: 1059-1524
Erasmus J, Braga VMM, 2006, Rho GTPase activation by cell-cell adhesion, Methods in Enzymology, Editors: Der, Hall, Publisher: Elsevier, Pages: 402-415
Zhang JK, Betson M, Erasmus J, et al., 2005, Actin at cell-cell junctions is composed of two dynamic and functional populations, JOURNAL OF CELL SCIENCE, Vol: 118, Pages: 5549-5562, ISSN: 0021-9533
Bayly JC, Douglas LM, Pretorius IS, et al., 2005, Characteristics of Flo11-dependent flocculation in Saccharomyces cerevisiae., FEMS Yeast Res, Vol: 5, Pages: 1151-1156, ISSN: 1567-1356
The FLO11-encoded flocculin is required for a variety of important phenotypes in Saccharomyces cerevisiae, including flocculation, adhesion to agar and plastic, invasive growth, pseudohyphae formation and biofilm development. We present evidence that Flo11p belongs to the Flo1-type class of flocculins rather than to the NewFlo class. Both Flo1-type and NewFlo yeast flocculation are inhibited by mannose. NewFlo flocculation, however, is also inhibited by several other carbohydrates including glucose, maltose and sucrose. These differences have in at least one case been shown to reflect differences in the structure of the carbohydrate-binding site of the flocculins. We report that Flo11p-dependent flocculation is inhibited by mannose, but not by glucose, maltose or sucrose. Furthermore, Flo11p contains a peptide sequence highly similar to one that has been shown to characterise Flo1-type flocculins. Further characterisation of the properties of Flo11p-dependent flocculation revealed that it is dependent on calcium, occurs only at cell densities greater than 1 x 10(8) ml(-1), and only occurs at acidic pH.
Zhang J, Betson M, Erasmus J, et al., 2005, Actin at cell-cell junctions is composed of twodynamic and functional populations
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