Limits...
A talin-dependent LFA-1 focal zone is formed by rapidly migrating T lymphocytes.

Smith A, Carrasco YR, Stanley P, Kieffer N, Batista FD, Hogg N - J. Cell Biol. (2005)

Bottom Line: Talin is essential for the stability and formation of the LFA-1 zone.Disruption of the talin-integrin link leads to loss of zone integrity and a substantial decrease in speed of migration on ICAM-1.This adhesive structure, which differs from the previously described integrin-containing attachments displayed by many other cell types, we have termed the "focal zone."

View Article: PubMed Central - PubMed

Affiliation: Leukocyte Adhesion Laboratory, Cancer Research UK London Research Institute, London WC2A 3PX, England, UK.

ABSTRACT
Cells such as fibroblasts and endothelial cells migrate through the coordinated responses of discrete integrin-containing focal adhesions and complexes. In contrast, little is known about the organization of integrins on the highly motile T lymphocyte. We have investigated the distribution, activity, and cytoskeletal linkage of the integrin lymphocyte function associated antigen-1 (LFA-1) on human T lymphocytes migrating on endothelial cells and on ligand intercellular adhesion molecule-1 (ICAM-1). The pattern of total LFA-1 varies from low expression in the lamellipodia to high expression in the uropod. However, high affinity, clustered LFA-1 is restricted to a mid-cell zone that remains stable over time and over a range of ICAM-1 densities. Talin is essential for the stability and formation of the LFA-1 zone. Disruption of the talin-integrin link leads to loss of zone integrity and a substantial decrease in speed of migration on ICAM-1. This adhesive structure, which differs from the previously described integrin-containing attachments displayed by many other cell types, we have termed the "focal zone."

Show MeSH

Related in: MedlinePlus

Structure and stability of the ICAM-1 binding zone on migrating T cells. Human T cells were added to ICAM-1–containing planar lipid bilayers (175 molecules/μm2) in the presence of 5 mM MgCl2 at 37°C. (A) The location of a concentrated zone of ICAM-1 (red) on a migrating T cell. (B) A T cell migrating over time displays the stability of the zone of ICAM-1 binding in relation to its intensity and cellular position. (C) The total amount of ICAM-1 within the zone of migrating T cells was calculated at time 0 (equals 100%) and the relative ICAM-1 levels were recorded at intervals over a period of 130 s. All results are expressed as an average of 10 cells ± SD. (D) The lack of ICAM-1 incorporation in the bilayer resulted in the failure of T cell attachment and polarization. Bars, 10 μm. (E) The density of ICAM-1 in the zone decreases as the ICAM-1 level in the lipid bilayer decreases (r2 = 0.9677). (F) The area occupied by the zone of ICAM-1 shows stability over a range of ICAM-1 concentrations (175 to 44 molecules/μm2) and then declines by 22 molecules/μm2. (G) The migration speed is constant between 175 and 44 molecules/μm2 and reduces significantly (P < 0.01) below this level. E–G were composed from values obtained from the same experiments (n = 5–7; ±SD). All images were taken with a 63× oil immersion objective. *, P < 0.01.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2171377&req=5

fig2: Structure and stability of the ICAM-1 binding zone on migrating T cells. Human T cells were added to ICAM-1–containing planar lipid bilayers (175 molecules/μm2) in the presence of 5 mM MgCl2 at 37°C. (A) The location of a concentrated zone of ICAM-1 (red) on a migrating T cell. (B) A T cell migrating over time displays the stability of the zone of ICAM-1 binding in relation to its intensity and cellular position. (C) The total amount of ICAM-1 within the zone of migrating T cells was calculated at time 0 (equals 100%) and the relative ICAM-1 levels were recorded at intervals over a period of 130 s. All results are expressed as an average of 10 cells ± SD. (D) The lack of ICAM-1 incorporation in the bilayer resulted in the failure of T cell attachment and polarization. Bars, 10 μm. (E) The density of ICAM-1 in the zone decreases as the ICAM-1 level in the lipid bilayer decreases (r2 = 0.9677). (F) The area occupied by the zone of ICAM-1 shows stability over a range of ICAM-1 concentrations (175 to 44 molecules/μm2) and then declines by 22 molecules/μm2. (G) The migration speed is constant between 175 and 44 molecules/μm2 and reduces significantly (P < 0.01) below this level. E–G were composed from values obtained from the same experiments (n = 5–7; ±SD). All images were taken with a 63× oil immersion objective. *, P < 0.01.

Mentions: To analyze LFA-1–ICAM-1 with minimal interference from other receptor pairs, we next investigated T cell migration on glycophosphoinositide-linked ICAM-1 incorporated into planar lipid bilayers (Dustin et al., 1997; Carrasco et al., 2004). In addition, this model permitted more detailed visualization of contact between ligand and receptor. In this setting, the striking feature of T cells was the formation of a single mid-cell region of concentrated ICAM-1 corresponding to the focal zone associated with T cells migrating on target cells (Fig. 2 A and Video 2, available at http://www.jcb.org/cgi/content/full/jcb.200412032/DC1). Observation over time showed that the zone maintained a constant cellular location (Fig. 2 B), and quantification of the density of ICAM-1 indicated that it also remained stable over time at ∼400 molecules/μm2 (Fig. 2 C). The process was totally ICAM-1 dependent, as the T cells failed to either attach or migrate in its absence (Fig. 2 D).


A talin-dependent LFA-1 focal zone is formed by rapidly migrating T lymphocytes.

Smith A, Carrasco YR, Stanley P, Kieffer N, Batista FD, Hogg N - J. Cell Biol. (2005)

Structure and stability of the ICAM-1 binding zone on migrating T cells. Human T cells were added to ICAM-1–containing planar lipid bilayers (175 molecules/μm2) in the presence of 5 mM MgCl2 at 37°C. (A) The location of a concentrated zone of ICAM-1 (red) on a migrating T cell. (B) A T cell migrating over time displays the stability of the zone of ICAM-1 binding in relation to its intensity and cellular position. (C) The total amount of ICAM-1 within the zone of migrating T cells was calculated at time 0 (equals 100%) and the relative ICAM-1 levels were recorded at intervals over a period of 130 s. All results are expressed as an average of 10 cells ± SD. (D) The lack of ICAM-1 incorporation in the bilayer resulted in the failure of T cell attachment and polarization. Bars, 10 μm. (E) The density of ICAM-1 in the zone decreases as the ICAM-1 level in the lipid bilayer decreases (r2 = 0.9677). (F) The area occupied by the zone of ICAM-1 shows stability over a range of ICAM-1 concentrations (175 to 44 molecules/μm2) and then declines by 22 molecules/μm2. (G) The migration speed is constant between 175 and 44 molecules/μm2 and reduces significantly (P < 0.01) below this level. E–G were composed from values obtained from the same experiments (n = 5–7; ±SD). All images were taken with a 63× oil immersion objective. *, P < 0.01.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171377&req=5

fig2: Structure and stability of the ICAM-1 binding zone on migrating T cells. Human T cells were added to ICAM-1–containing planar lipid bilayers (175 molecules/μm2) in the presence of 5 mM MgCl2 at 37°C. (A) The location of a concentrated zone of ICAM-1 (red) on a migrating T cell. (B) A T cell migrating over time displays the stability of the zone of ICAM-1 binding in relation to its intensity and cellular position. (C) The total amount of ICAM-1 within the zone of migrating T cells was calculated at time 0 (equals 100%) and the relative ICAM-1 levels were recorded at intervals over a period of 130 s. All results are expressed as an average of 10 cells ± SD. (D) The lack of ICAM-1 incorporation in the bilayer resulted in the failure of T cell attachment and polarization. Bars, 10 μm. (E) The density of ICAM-1 in the zone decreases as the ICAM-1 level in the lipid bilayer decreases (r2 = 0.9677). (F) The area occupied by the zone of ICAM-1 shows stability over a range of ICAM-1 concentrations (175 to 44 molecules/μm2) and then declines by 22 molecules/μm2. (G) The migration speed is constant between 175 and 44 molecules/μm2 and reduces significantly (P < 0.01) below this level. E–G were composed from values obtained from the same experiments (n = 5–7; ±SD). All images were taken with a 63× oil immersion objective. *, P < 0.01.
Mentions: To analyze LFA-1–ICAM-1 with minimal interference from other receptor pairs, we next investigated T cell migration on glycophosphoinositide-linked ICAM-1 incorporated into planar lipid bilayers (Dustin et al., 1997; Carrasco et al., 2004). In addition, this model permitted more detailed visualization of contact between ligand and receptor. In this setting, the striking feature of T cells was the formation of a single mid-cell region of concentrated ICAM-1 corresponding to the focal zone associated with T cells migrating on target cells (Fig. 2 A and Video 2, available at http://www.jcb.org/cgi/content/full/jcb.200412032/DC1). Observation over time showed that the zone maintained a constant cellular location (Fig. 2 B), and quantification of the density of ICAM-1 indicated that it also remained stable over time at ∼400 molecules/μm2 (Fig. 2 C). The process was totally ICAM-1 dependent, as the T cells failed to either attach or migrate in its absence (Fig. 2 D).

Bottom Line: Talin is essential for the stability and formation of the LFA-1 zone.Disruption of the talin-integrin link leads to loss of zone integrity and a substantial decrease in speed of migration on ICAM-1.This adhesive structure, which differs from the previously described integrin-containing attachments displayed by many other cell types, we have termed the "focal zone."

View Article: PubMed Central - PubMed

Affiliation: Leukocyte Adhesion Laboratory, Cancer Research UK London Research Institute, London WC2A 3PX, England, UK.

ABSTRACT
Cells such as fibroblasts and endothelial cells migrate through the coordinated responses of discrete integrin-containing focal adhesions and complexes. In contrast, little is known about the organization of integrins on the highly motile T lymphocyte. We have investigated the distribution, activity, and cytoskeletal linkage of the integrin lymphocyte function associated antigen-1 (LFA-1) on human T lymphocytes migrating on endothelial cells and on ligand intercellular adhesion molecule-1 (ICAM-1). The pattern of total LFA-1 varies from low expression in the lamellipodia to high expression in the uropod. However, high affinity, clustered LFA-1 is restricted to a mid-cell zone that remains stable over time and over a range of ICAM-1 densities. Talin is essential for the stability and formation of the LFA-1 zone. Disruption of the talin-integrin link leads to loss of zone integrity and a substantial decrease in speed of migration on ICAM-1. This adhesive structure, which differs from the previously described integrin-containing attachments displayed by many other cell types, we have termed the "focal zone."

Show MeSH
Related in: MedlinePlus