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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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Medium affects morphology of EPs and EP bridges.A–B: Photomicrographs of EPs cultured alone in BEGM (A) depict a cuboidal EP morphology compared to a flattened, squamous morphology displayed in EPs grown in BEGM:EGM-2 with 5% FBS (B). C–D: Composites of microtubules via acetylated α-tubulin (green), F-actin (red), and nucleus (blue) immunostaining in EPs cultured alone in BEGM (C) show a more organized cytoskeleton compared to EPs grown in BEGM:EGM-2 with 5% FBS (D). E–H: Expression of microtubules (green) and F-actin (red) in EP bridges without nuclei (E–F) or with a nucleus (G–H) in EPs cultured alone in BEGM (E, G) or BEGM:EGM-2 with 5% FBS (F, H). Scale bars: (A–G), 50 µm; (Gi, Hi), 10 µm.
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pone-0008930-g002: Medium affects morphology of EPs and EP bridges.A–B: Photomicrographs of EPs cultured alone in BEGM (A) depict a cuboidal EP morphology compared to a flattened, squamous morphology displayed in EPs grown in BEGM:EGM-2 with 5% FBS (B). C–D: Composites of microtubules via acetylated α-tubulin (green), F-actin (red), and nucleus (blue) immunostaining in EPs cultured alone in BEGM (C) show a more organized cytoskeleton compared to EPs grown in BEGM:EGM-2 with 5% FBS (D). E–H: Expression of microtubules (green) and F-actin (red) in EP bridges without nuclei (E–F) or with a nucleus (G–H) in EPs cultured alone in BEGM (E, G) or BEGM:EGM-2 with 5% FBS (F, H). Scale bars: (A–G), 50 µm; (Gi, Hi), 10 µm.

Mentions: Long, thin EP structures - EP bridges - established connections between EP islands (Figure 1, F to H). Some EP bridges contained nuclei, while all EP bridges were F-actin and microtubule composites (Figure 1, I to K), in contrast to cytonemes and TNTs which contain only F-actin [4], [5]. EP bridge formation was not dependent on the confluence of co-cultures as these structures were observed forming both before and after confluence. Similar to TNT structure, EP bridges hovered above the underlying substratum of ECs (Figure 1L). Possessing both dynamic and static morphological characteristics, EP bridges remained in place up to 2 days and ranged from 50 µm to over a millimeter in length. Time-lapse light microscopy showed EP bridges extending (Figure S2) or contracting (Movie S1) as EP islands moved apart or together. EP bridges were also much wider than cytonemes or TNTs with diameters of 1 to 20 µm. Furthermore, EP bridge formation was not predicated on the presence of ECs as EP bridges were observed in EPs cultured with FBs (Figure S3) or EPs cultured alone (Figure 2).


Tubular bridges for bronchial epithelial cell migration and communication.

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

Medium affects morphology of EPs and EP bridges.A–B: Photomicrographs of EPs cultured alone in BEGM (A) depict a cuboidal EP morphology compared to a flattened, squamous morphology displayed in EPs grown in BEGM:EGM-2 with 5% FBS (B). C–D: Composites of microtubules via acetylated α-tubulin (green), F-actin (red), and nucleus (blue) immunostaining in EPs cultured alone in BEGM (C) show a more organized cytoskeleton compared to EPs grown in BEGM:EGM-2 with 5% FBS (D). E–H: Expression of microtubules (green) and F-actin (red) in EP bridges without nuclei (E–F) or with a nucleus (G–H) in EPs cultured alone in BEGM (E, G) or BEGM:EGM-2 with 5% FBS (F, H). Scale bars: (A–G), 50 µm; (Gi, Hi), 10 µm.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0008930-g002: Medium affects morphology of EPs and EP bridges.A–B: Photomicrographs of EPs cultured alone in BEGM (A) depict a cuboidal EP morphology compared to a flattened, squamous morphology displayed in EPs grown in BEGM:EGM-2 with 5% FBS (B). C–D: Composites of microtubules via acetylated α-tubulin (green), F-actin (red), and nucleus (blue) immunostaining in EPs cultured alone in BEGM (C) show a more organized cytoskeleton compared to EPs grown in BEGM:EGM-2 with 5% FBS (D). E–H: Expression of microtubules (green) and F-actin (red) in EP bridges without nuclei (E–F) or with a nucleus (G–H) in EPs cultured alone in BEGM (E, G) or BEGM:EGM-2 with 5% FBS (F, H). Scale bars: (A–G), 50 µm; (Gi, Hi), 10 µm.
Mentions: Long, thin EP structures - EP bridges - established connections between EP islands (Figure 1, F to H). Some EP bridges contained nuclei, while all EP bridges were F-actin and microtubule composites (Figure 1, I to K), in contrast to cytonemes and TNTs which contain only F-actin [4], [5]. EP bridge formation was not dependent on the confluence of co-cultures as these structures were observed forming both before and after confluence. Similar to TNT structure, EP bridges hovered above the underlying substratum of ECs (Figure 1L). Possessing both dynamic and static morphological characteristics, EP bridges remained in place up to 2 days and ranged from 50 µm to over a millimeter in length. Time-lapse light microscopy showed EP bridges extending (Figure S2) or contracting (Movie S1) as EP islands moved apart or together. EP bridges were also much wider than cytonemes or TNTs with diameters of 1 to 20 µm. Furthermore, EP bridge formation was not predicated on the presence of ECs as EP bridges were observed in EPs cultured with FBs (Figure S3) or EPs cultured alone (Figure 2).

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