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Tubular bridges for bronchial epithelial cell migration and communication.

Zani BG, Indolfi L, Edelman ER - PLoS ONE (2010)

Bottom Line: Intercellular signaling enables cell masses to communicate through endocrine pathways at a distance or by direct contact over shorter dimensions.Using various cellular imaging techniques on human tissue cultures, we identified two types of tubular, bronchial epithelial (EP) connections, up to a millimeter in length, designated EP bridges.These tubular EP conduits may represent an ultra long-range form of direct intercellular communication and a completely new mechanism of tissue-mediated cell migration.

View Article: PubMed Central - PubMed

Affiliation: Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America. zani@mit.edu

ABSTRACT

Background: Biological processes from embryogenesis to tumorigenesis rely on the coordinated coalescence of cells and synchronized cell-to-cell communication. Intercellular signaling enables cell masses to communicate through endocrine pathways at a distance or by direct contact over shorter dimensions. Cellular bridges, the longest direct connections between cells, facilitate transfer of cellular signals and components over hundreds of microns in vitro and in vivo.

Methodology/principal findings: Using various cellular imaging techniques on human tissue cultures, we identified two types of tubular, bronchial epithelial (EP) connections, up to a millimeter in length, designated EP bridges. Structurally distinct from other cellular connections, the first type of EP bridge may mediate transport of cellular material between cells, while the second type of EP bridge is functionally distinct from all other cellular connections by mediating migration of epithelial cells between EP masses. Morphological and biochemical interactions with other cell types differentially regulated the nuclear factor-kappaB and cyclooxygenase inflammatory pathways, resulting in increased levels of inflammatory molecules that impeded EP bridge formation. Pharmacologic inhibition of these inflammatory pathways caused increased morphological and mobility changes stimulating the biogenesis of EP bridges, in part through the upregulation of reactive oxygen species pathways.

Conclusions/significance: EP bridge formation appears to be a normal response of EP physiology in vitro, which is differentially inhibited by inflammatory cellular pathways depending upon the morphological and biochemical interactions between EP cells and other cell types. These tubular EP conduits may represent an ultra long-range form of direct intercellular communication and a completely new mechanism of tissue-mediated cell migration.

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Related in: MedlinePlus

Cell migration via EP bridges.A: An individual cell migrating over 10 h through an EP bridge that connects EP islands (not a connection between only two cells). The cell expanded the elastic structure of the EP bridge, which returned to original size after the cell passed (0–6 h). The migrating cell exited the EP bridge through an elastic sheath and migrated into the EP island (7–10 h). EP bridge length remained relatively stable over 31 h as ECs grew underneath the bridge. The EP bridge measured 623 µm at 0 h and 562 µm at 31 h. B: Lysosome (red) and nucleus (blue) staining in EPs/ECs show nuclei co-localized with lysosomes in an EP bridge connecting two EP islands. C–D: F-actin (red), Golgi marker (green), and nucleus (blue) immunostaining show co-localization of nuclei and Golgi suggesting an individual cell expanded the EP bridge structure (C-Ci), while multiple cells were within another EP bridge (D). Scale bars: (A 0 h and 31 h, B, C, D), 50 µm; (A subpanels, Ci), 10 µm.
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pone-0008930-g004: Cell migration via EP bridges.A: An individual cell migrating over 10 h through an EP bridge that connects EP islands (not a connection between only two cells). The cell expanded the elastic structure of the EP bridge, which returned to original size after the cell passed (0–6 h). The migrating cell exited the EP bridge through an elastic sheath and migrated into the EP island (7–10 h). EP bridge length remained relatively stable over 31 h as ECs grew underneath the bridge. The EP bridge measured 623 µm at 0 h and 562 µm at 31 h. B: Lysosome (red) and nucleus (blue) staining in EPs/ECs show nuclei co-localized with lysosomes in an EP bridge connecting two EP islands. C–D: F-actin (red), Golgi marker (green), and nucleus (blue) immunostaining show co-localization of nuclei and Golgi suggesting an individual cell expanded the EP bridge structure (C-Ci), while multiple cells were within another EP bridge (D). Scale bars: (A 0 h and 31 h, B, C, D), 50 µm; (A subpanels, Ci), 10 µm.

Mentions: To date, cytonemes and TNTs have not yet been shown to transport genetic material, let alone cells; therefore, the existence of nuclei within a high percentage of EP bridges raised the question if genetic material was being transported between cells and/or cells were migrating between EP islands. Time-lapse light microscopy showed what appeared to be entire cells migrating through EP bridges (Figure 4A and Figures S8 to S9 with corresponding Movies S2 and S3, respectively). The migrating cells seemed to expand an elastic, tubular morphology of EP bridges which returned to original size as the cells migrated through the bridges. The possibility does exist that nuclei alone are being transported between EPs; however, in support of entire cells, and not just nuclei, migrating through EP bridges, immunofluorescent imaging showed co-localization of all nuclei with other cellular markers: lysosomes or Golgi apparatuses (Figure 4, B to D and Figure S7B). Also, the presence of the marker for non-mucus, secretory Clara cells within some EP bridges further supported the notion that specific EP bridges act as conduits for the movement of cells between EP islands (Figure S10). Further studies are needed to determine the specific types of cells moving within all EP bridges, but based on the composition of EP islands the most likely cell types migrating via these conduits are Clara cells and undifferentiated, transitional EPs. Overall these findings implied that two distinct connections between EP islands existed: the first being simple, tubular connections possibly mediating transport of cellular material between two cells (type I); and the second being complex, tubular connections facilitating migration of entire cells between multi-cellular EP islands (type II).


Tubular bridges for bronchial epithelial cell migration and communication.

Zani BG, Indolfi L, Edelman ER - PLoS ONE (2010)

Cell migration via EP bridges.A: An individual cell migrating over 10 h through an EP bridge that connects EP islands (not a connection between only two cells). The cell expanded the elastic structure of the EP bridge, which returned to original size after the cell passed (0–6 h). The migrating cell exited the EP bridge through an elastic sheath and migrated into the EP island (7–10 h). EP bridge length remained relatively stable over 31 h as ECs grew underneath the bridge. The EP bridge measured 623 µm at 0 h and 562 µm at 31 h. B: Lysosome (red) and nucleus (blue) staining in EPs/ECs show nuclei co-localized with lysosomes in an EP bridge connecting two EP islands. C–D: F-actin (red), Golgi marker (green), and nucleus (blue) immunostaining show co-localization of nuclei and Golgi suggesting an individual cell expanded the EP bridge structure (C-Ci), while multiple cells were within another EP bridge (D). Scale bars: (A 0 h and 31 h, B, C, D), 50 µm; (A subpanels, Ci), 10 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2812493&req=5

pone-0008930-g004: Cell migration via EP bridges.A: An individual cell migrating over 10 h through an EP bridge that connects EP islands (not a connection between only two cells). The cell expanded the elastic structure of the EP bridge, which returned to original size after the cell passed (0–6 h). The migrating cell exited the EP bridge through an elastic sheath and migrated into the EP island (7–10 h). EP bridge length remained relatively stable over 31 h as ECs grew underneath the bridge. The EP bridge measured 623 µm at 0 h and 562 µm at 31 h. B: Lysosome (red) and nucleus (blue) staining in EPs/ECs show nuclei co-localized with lysosomes in an EP bridge connecting two EP islands. C–D: F-actin (red), Golgi marker (green), and nucleus (blue) immunostaining show co-localization of nuclei and Golgi suggesting an individual cell expanded the EP bridge structure (C-Ci), while multiple cells were within another EP bridge (D). Scale bars: (A 0 h and 31 h, B, C, D), 50 µm; (A subpanels, Ci), 10 µm.
Mentions: To date, cytonemes and TNTs have not yet been shown to transport genetic material, let alone cells; therefore, the existence of nuclei within a high percentage of EP bridges raised the question if genetic material was being transported between cells and/or cells were migrating between EP islands. Time-lapse light microscopy showed what appeared to be entire cells migrating through EP bridges (Figure 4A and Figures S8 to S9 with corresponding Movies S2 and S3, respectively). The migrating cells seemed to expand an elastic, tubular morphology of EP bridges which returned to original size as the cells migrated through the bridges. The possibility does exist that nuclei alone are being transported between EPs; however, in support of entire cells, and not just nuclei, migrating through EP bridges, immunofluorescent imaging showed co-localization of all nuclei with other cellular markers: lysosomes or Golgi apparatuses (Figure 4, B to D and Figure S7B). Also, the presence of the marker for non-mucus, secretory Clara cells within some EP bridges further supported the notion that specific EP bridges act as conduits for the movement of cells between EP islands (Figure S10). Further studies are needed to determine the specific types of cells moving within all EP bridges, but based on the composition of EP islands the most likely cell types migrating via these conduits are Clara cells and undifferentiated, transitional EPs. Overall these findings implied that two distinct connections between EP islands existed: the first being simple, tubular connections possibly mediating transport of cellular material between two cells (type I); and the second being complex, tubular connections facilitating migration of entire cells between multi-cellular EP islands (type II).

Bottom Line: Intercellular signaling enables cell masses to communicate through endocrine pathways at a distance or by direct contact over shorter dimensions.Using various cellular imaging techniques on human tissue cultures, we identified two types of tubular, bronchial epithelial (EP) connections, up to a millimeter in length, designated EP bridges.These tubular EP conduits may represent an ultra long-range form of direct intercellular communication and a completely new mechanism of tissue-mediated cell migration.

View Article: PubMed Central - PubMed

Affiliation: Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America. zani@mit.edu

ABSTRACT

Background: Biological processes from embryogenesis to tumorigenesis rely on the coordinated coalescence of cells and synchronized cell-to-cell communication. Intercellular signaling enables cell masses to communicate through endocrine pathways at a distance or by direct contact over shorter dimensions. Cellular bridges, the longest direct connections between cells, facilitate transfer of cellular signals and components over hundreds of microns in vitro and in vivo.

Methodology/principal findings: Using various cellular imaging techniques on human tissue cultures, we identified two types of tubular, bronchial epithelial (EP) connections, up to a millimeter in length, designated EP bridges. Structurally distinct from other cellular connections, the first type of EP bridge may mediate transport of cellular material between cells, while the second type of EP bridge is functionally distinct from all other cellular connections by mediating migration of epithelial cells between EP masses. Morphological and biochemical interactions with other cell types differentially regulated the nuclear factor-kappaB and cyclooxygenase inflammatory pathways, resulting in increased levels of inflammatory molecules that impeded EP bridge formation. Pharmacologic inhibition of these inflammatory pathways caused increased morphological and mobility changes stimulating the biogenesis of EP bridges, in part through the upregulation of reactive oxygen species pathways.

Conclusions/significance: EP bridge formation appears to be a normal response of EP physiology in vitro, which is differentially inhibited by inflammatory cellular pathways depending upon the morphological and biochemical interactions between EP cells and other cell types. These tubular EP conduits may represent an ultra long-range form of direct intercellular communication and a completely new mechanism of tissue-mediated cell migration.

Show MeSH
Related in: MedlinePlus