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Ezrin and moesin are required for efficient T cell adhesion and homing to lymphoid organs.

Chen EJ, Shaffer MH, Williamson EK, Huang Y, Burkhardt JK - PLoS ONE (2013)

Bottom Line: Members of the ezrin, radixin and moesin (ERM) family of actin-binding proteins have been implicated in several aspects of this process, but studies have yielded conflicting results.In vivo, ERM-deficient T cells showed defects in homing to lymphoid organs.Taken together, these results show that ERM proteins are largely dispensable for T cell chemotaxis, but are important for β1 integrin function and homing to lymphoid organs.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Pennsylvania, USA.

ABSTRACT
T cell trafficking between the blood and lymphoid organs is a complex, multistep process that requires several highly dynamic and coordinated changes in cyto-architecture. Members of the ezrin, radixin and moesin (ERM) family of actin-binding proteins have been implicated in several aspects of this process, but studies have yielded conflicting results. Using mice with a conditional deletion of ezrin in CD4+ cells and moesin-specific siRNA, we generated T cells lacking ERM proteins, and investigated the effect on specific events required for T cell trafficking. ERM-deficient T cells migrated normally in multiple in vitro and in vivo assays, and could undergo efficient diapedesis in vitro. However, these cells were impaired in their ability to adhere to the β1 integrin ligand fibronectin, and to polarize appropriately in response to fibronectin and VCAM-1 binding. This defect was specific for β1 integrins, as adhesion and polarization in response to ICAM-1 were normal. In vivo, ERM-deficient T cells showed defects in homing to lymphoid organs. Taken together, these results show that ERM proteins are largely dispensable for T cell chemotaxis, but are important for β1 integrin function and homing to lymphoid organs.

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ERM-deficient T cells can migrate efficiently in confined spaces.A) Wild-type or ERM-deficient T cells were placed in a 5 µm pore collagen gel in the absence (top panels) or presence (bottom panels) of a CCL19 gradient, and cell migration was imaged for 4 hours at 37°C. Tracks of individual cells are presented with the same point of origin. Data are representative of three experiments. Quantitative analysis is presented in Tables 1 and 2. B and C) Frequency of individual cell velocities in (A) in the absence (B) or presence (C) of chemokine. Data are representative of at least three collagen gels per condition in two independent experiments.
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pone-0052368-g002: ERM-deficient T cells can migrate efficiently in confined spaces.A) Wild-type or ERM-deficient T cells were placed in a 5 µm pore collagen gel in the absence (top panels) or presence (bottom panels) of a CCL19 gradient, and cell migration was imaged for 4 hours at 37°C. Tracks of individual cells are presented with the same point of origin. Data are representative of three experiments. Quantitative analysis is presented in Tables 1 and 2. B and C) Frequency of individual cell velocities in (A) in the absence (B) or presence (C) of chemokine. Data are representative of at least three collagen gels per condition in two independent experiments.

Mentions: To further assess the ability of ERM-deficient T cells to migrate within confined spaces, we tested chemotaxis in a three-dimensional (3D) setting. In collagen gels with an average pore size of 5 µm and in the absence of chemokine, ERM-deficient T cells migrated as efficiently as wild-type T cells (Figure 2A, top panels). Although no differences between the two populations were observed in track length, meandering index, or directionality, the average velocity of ERM-deficient T cells was modestly increased in the absence of chemokine (Table 1). Plotting the data as a frequency histogram (Figure 2B) revealed that the velocities of randomly migrating ERM-deficient T cells are highly variable, and the population lacks the Gaussian distribution observed in wild-type cells. Wild-type and ERM-deficient T cells were also tested for chemotaxis in 3D collagen gels in response to a gradient of CCL19. As anticipated, exposure of wild-type T cells to chemokine triggered an increase in velocity and enhanced directional migration (Figure 2A, bottom panels, and Table 2). Consistent with our findings using the transwell assay, ERM-deficient T cells also chemotaxed efficiently. As shown in Table 2, chemotaxing ERM-deficient T cells exhibited velocities, meandering indices and track lengths similar to wild-type cells. Frequency histograms showed that ERM-deficient and wild-type T cells exhibited comparable Gaussian distributions (Figure 2C). Similar results were obtained if we increased the collagen concentration to yield gels with a predicted average pore size of 2 µm (data not shown). Taken together, these findings show that loss of ERM protein expression does not impair T cell migration or chemotaxis per se, though it does affect movement through confined spaces in some experimental settings.


Ezrin and moesin are required for efficient T cell adhesion and homing to lymphoid organs.

Chen EJ, Shaffer MH, Williamson EK, Huang Y, Burkhardt JK - PLoS ONE (2013)

ERM-deficient T cells can migrate efficiently in confined spaces.A) Wild-type or ERM-deficient T cells were placed in a 5 µm pore collagen gel in the absence (top panels) or presence (bottom panels) of a CCL19 gradient, and cell migration was imaged for 4 hours at 37°C. Tracks of individual cells are presented with the same point of origin. Data are representative of three experiments. Quantitative analysis is presented in Tables 1 and 2. B and C) Frequency of individual cell velocities in (A) in the absence (B) or presence (C) of chemokine. Data are representative of at least three collagen gels per condition in two independent experiments.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585410&req=5

pone-0052368-g002: ERM-deficient T cells can migrate efficiently in confined spaces.A) Wild-type or ERM-deficient T cells were placed in a 5 µm pore collagen gel in the absence (top panels) or presence (bottom panels) of a CCL19 gradient, and cell migration was imaged for 4 hours at 37°C. Tracks of individual cells are presented with the same point of origin. Data are representative of three experiments. Quantitative analysis is presented in Tables 1 and 2. B and C) Frequency of individual cell velocities in (A) in the absence (B) or presence (C) of chemokine. Data are representative of at least three collagen gels per condition in two independent experiments.
Mentions: To further assess the ability of ERM-deficient T cells to migrate within confined spaces, we tested chemotaxis in a three-dimensional (3D) setting. In collagen gels with an average pore size of 5 µm and in the absence of chemokine, ERM-deficient T cells migrated as efficiently as wild-type T cells (Figure 2A, top panels). Although no differences between the two populations were observed in track length, meandering index, or directionality, the average velocity of ERM-deficient T cells was modestly increased in the absence of chemokine (Table 1). Plotting the data as a frequency histogram (Figure 2B) revealed that the velocities of randomly migrating ERM-deficient T cells are highly variable, and the population lacks the Gaussian distribution observed in wild-type cells. Wild-type and ERM-deficient T cells were also tested for chemotaxis in 3D collagen gels in response to a gradient of CCL19. As anticipated, exposure of wild-type T cells to chemokine triggered an increase in velocity and enhanced directional migration (Figure 2A, bottom panels, and Table 2). Consistent with our findings using the transwell assay, ERM-deficient T cells also chemotaxed efficiently. As shown in Table 2, chemotaxing ERM-deficient T cells exhibited velocities, meandering indices and track lengths similar to wild-type cells. Frequency histograms showed that ERM-deficient and wild-type T cells exhibited comparable Gaussian distributions (Figure 2C). Similar results were obtained if we increased the collagen concentration to yield gels with a predicted average pore size of 2 µm (data not shown). Taken together, these findings show that loss of ERM protein expression does not impair T cell migration or chemotaxis per se, though it does affect movement through confined spaces in some experimental settings.

Bottom Line: Members of the ezrin, radixin and moesin (ERM) family of actin-binding proteins have been implicated in several aspects of this process, but studies have yielded conflicting results.In vivo, ERM-deficient T cells showed defects in homing to lymphoid organs.Taken together, these results show that ERM proteins are largely dispensable for T cell chemotaxis, but are important for β1 integrin function and homing to lymphoid organs.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Pennsylvania, USA.

ABSTRACT
T cell trafficking between the blood and lymphoid organs is a complex, multistep process that requires several highly dynamic and coordinated changes in cyto-architecture. Members of the ezrin, radixin and moesin (ERM) family of actin-binding proteins have been implicated in several aspects of this process, but studies have yielded conflicting results. Using mice with a conditional deletion of ezrin in CD4+ cells and moesin-specific siRNA, we generated T cells lacking ERM proteins, and investigated the effect on specific events required for T cell trafficking. ERM-deficient T cells migrated normally in multiple in vitro and in vivo assays, and could undergo efficient diapedesis in vitro. However, these cells were impaired in their ability to adhere to the β1 integrin ligand fibronectin, and to polarize appropriately in response to fibronectin and VCAM-1 binding. This defect was specific for β1 integrins, as adhesion and polarization in response to ICAM-1 were normal. In vivo, ERM-deficient T cells showed defects in homing to lymphoid organs. Taken together, these results show that ERM proteins are largely dispensable for T cell chemotaxis, but are important for β1 integrin function and homing to lymphoid organs.

Show MeSH
Related in: MedlinePlus