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Project description:Ephrin-A5 modulates transcriptional responses to EphA2 activation
| PRJNA576595 | ENA
Project description:PurposeFine focusing of light by the eye lens onto the retina relies on the ability of the lens to change shape during the process of accommodation. Little is known about the cellular structures that regulate elasticity and resilience. We tested whether Eph-ephrin signaling is involved in lens biomechanical properties.MethodsWe used confocal microscopy and tissue mechanical testing to examine mouse lenses with genetic disruption of EphA2 or ephrin-A5.ResultsConfocal imaging revealed misalignment of the suture between each shell of newly added fiber cells in knockout lenses. Despite having disordered sutures, loss of EphA2 or ephrin-A5 did not affect lens stiffness. Surprisingly, knockout lenses were more resilient and recovered almost completely after load removal. Confocal microscopy and quantitative image analysis from live lenses before, during, and after compression revealed that knockout lenses had misaligned Y-sutures, leading to a change in force distribution during compression. Knockout lenses displayed decreased separation of fiber cell tips at the anterior suture at high loads and had more complete recovery after load removal, which leads to improved whole-lens resiliency.ConclusionsEphA2 and ephrin-A5 are needed for normal patterning of fiber cell tips and the formation of a well-aligned Y-suture with fiber tips stacked on top of previous generations of fiber cells. The misalignment of lens sutures leads to increased resilience after compression. The data suggest that alignment of the Y-suture may constrain the overall elasticity and resilience of the lens.
| S-EPMC8648058 | biostudies-literature
Project description:Ligand binding induces extensive spatial reorganization and clustering of the EphA2 receptor at the cell membrane. It has previously been shown that the nanoscale spatial distribution of ligands modulates EphA2 receptor reorganization, activation and the invasive properties of cancer cells. However, the mechanisms by which cells transduce ligand nanoscale spatial distribution signals have not been elucidated. Here we used DNA origami nanocalipers to control the positions of ephrin-A5 ligands at the nanoscale and investigated the transcriptional responses following ligand binding. Using mRNA sequencing, we determined the transcriptional profiles of glioblastoma cells treated with nanocalipers presenting a single ephrin-A5 dimer or two dimers spaced 14, 40 or 100 nm apart. We observed divergent transcriptional responses to ephrin-A5 nano-organization, with ephrin-A5 dimers spaced 40 or 100 nm apart showing the highest levels of differential expressed genes compared to treatment with n anocalipers that do not present ephrin-A5. These findings show that the nanoscale organization of ephrin-A5 modulates transcriptional responses to EphA2 activation.
2020-04-07 | GSE138622 | GEO
Project description:The receptor tyrosine kinase EphA2 interacts with its glycosylphosphatidylinositol (GPI)-linked ephrin-A1 ligand in a juxtacrine configuration. The soluble ephrin-A1 protein, without its GPI membrane linker, fails to activate EphA2. However, preclustered ephrin-A1 protein is active in solution and has been frequently used to trigger the EphA2 receptor. Although this approach has yielded insights into EphA2 signaling, preclustered ligands bypass natural receptor clustering processes and thus mask any role of clustering as a signal regulatory mechanism. Here, we present EphA2-expressing cells with a fusion protein of monomeric ephrin-A1 (mEA1) and enhanced monomeric yellow fluorescent protein that is linked to a supported lipid bilayer via a nickel-decahistidine anchor. The mEA1 is homogeneously dispersed, laterally mobile, and monomeric as measured by fluorescence imaging, correlation spectroscopy, and photon counting histogram analysis, respectively. Ephrin-A1 presented in this manner activates EphA2 on the surface of MDA-MB-231 human breast cancer cells, as measured by EphA2 phosphorylation and degradation. Spatial mutation experiments in which nanopatterns on the underlying substrate restrict mEA1 movement in the supported lipid bilayer reveal spatio-mechanical regulation of this signaling pathway, consistent with recently reported observations using a synthetically cross-linked ephrin-A1 dimer.
| S-EPMC3297811 | biostudies-other
Project description:Ligand binding induces extensive spatial reorganization and clustering of the EphA2 receptor at the cell membrane. It has previously been shown that the nanoscale spatial distribution of ligands modulates EphA2 receptor reorganization, activation and the invasive properties of cancer cells. However, the mechanisms by which cells transduce ligand nanoscale spatial distribution signals have not been elucidated. Here we used DNA origami nanocalipers to control the positions of ephrin-A5 ligands at the nanoscale and investigated the transcriptional responses following ligand binding. Using mRNA sequencing, we determined the transcriptional profiles of glioblastoma cells treated with nanocalipers presenting a single ephrin-A5 dimer or two dimers spaced 14, 40 or 100 nm apart. We observed divergent transcriptional responses to ephrin-A5 nano-organization, with ephrin-A5 dimers spaced 40 or 100 nm apart showing the highest levels of differential expressed genes compared to treatment with n anocalipers that do not present ephrin-A5. These findings show that the nanoscale organization of ephrin-A5 modulates transcriptional responses to EphA2 activation.
2020-04-07 | GSE138620 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2015-11-04 | E-GEOD-66929 | biostudies-arrayexpress
Project description:During brain development, growth cones respond to attractive and repulsive axon guidance cues. How growth cones integrate guidance instructions is poorly understood. Here, we demonstrate a link between BDNF (brain derived neurotrophic factor), promoting axonal branching and ephrin-A5, mediating axonal repulsion via Eph receptor tyrosine kinase activation. BDNF enhanced growth cone filopodial dynamics and neurite branching of primary neurons. We show that ephrin-A5 antagonized this BDNF-evoked neuronal motility. BDNF increased ERK phosphorylation (P-ERK) and nuclear ERK entry. Ephrin-A5 suppressed BDNF-induced ERK activity and might sequester P-ERK in the cytoplasm. Neurotrophins are well established stimulators of a neuronal immediate early gene (IEG) response. This is confirmed in this study by e.g. c-fos, Egr1 and Arc upregulation upon BDNF application. This BDNF-evoked IEG response required the transcription factor SRF (serum response factor). Notably, ephrin-A5 suppressed a BDNF-evoked neuronal IEG response, suggesting a role of Eph receptors in modulating gene expression. In opposite to IEGs, long-term ephrin-A5 application induced cytoskeletal gene expression of tropomyosin and actinin. To uncover specific Eph receptors mediating ephrin-As impact on neurotrophin signaling, EphA7 deficient mice were analyzed. In EphA7 deficient neurons alterations in growth cone morphology were observed. However, ephrin-A5 still counteracted neurotrophin signaling suggesting that EphA7 is not required for ephrin and BDNF crosstalk. In sum, our data suggest an interaction of ephrin-As and neurotrophin signaling pathways converging at ERK signaling and nuclear gene activity. As ephrins are involved in development and function of many organs, such modulation of receptor tyrosine kinase signaling and gene expression by Ephs might not be limited to the nervous system.
| S-EPMC3191169 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2014-02-10 | E-GEOD-49852 | biostudies-arrayexpress
Project description:The Eph receptor tyrosine kinase/ephrin ligand system regulates a wide spectrum of physiological processes, while its dysregulation has been implicated in cancer progression. The human EphA3 receptor is widely upregulated in the tumor microenvironment and is highly expressed in some types of cancer cells. Furthermore, EphA3 is among the most highly mutated genes in lung cancer and it is also frequently mutated in other cancers. We report the structure of the ligand-binding domain of the EphA3 receptor in complex with its preferred ligand, ephrin-A5. The structure of the complex reveals a pronounced tilt of the ephrin-A5 ligand compared to its orientation when bound to the EphA2 and EphB2 receptors and similar to its orientation when bound to EphA4. This tilt brings an additional area of ephrin-A5 into contact with regions of EphA3 outside the ephrin-binding pocket thereby enlarging the size of the interface, which is consistent with the high binding affinity of ephrin-A5 for EphA3. This large variation in the tilt of ephrin-A5 bound to different Eph receptors has not been previously observed for other ephrins.
| S-EPMC4439037 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2014-12-18 | E-GEOD-60411 | biostudies-arrayexpress