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Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo

Keratin intermediate filaments (IF) are obligate heteropolymers containing equal amounts of type I and type II keratin. We have previously shown that microinjected biotinylated type I keratin is rapidly incorporated into endogenous bundles of keratin IF (tonofilaments) of PtK2 cells. In this study w...

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Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1993
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119605/
https://www.ncbi.nlm.nih.gov/pubmed/7686161
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collection PubMed
description Keratin intermediate filaments (IF) are obligate heteropolymers containing equal amounts of type I and type II keratin. We have previously shown that microinjected biotinylated type I keratin is rapidly incorporated into endogenous bundles of keratin IF (tonofilaments) of PtK2 cells. In this study we show that the earliest steps in the assembly of keratin subunits into tonofilaments involve the extremely rapid formation of discrete aggregates of microinjected keratin. These are seen as fluorescent spots containing both type I and type II keratins within 1 min post-injection as determined by double label immunofluorescence. These observations suggest that endogenous type II keratin subunits can be rapidly mobilized from their endogenous state to form complexes with the injected type I protein. Furthermore, confocal microscopy and immunogold electron microscopy suggest that the type I-type II keratin spots from in close association with the endogenous keratin IF network. When the biotinylated protein is injected at concentrations of 0.3-0.5 mg/ml, the organization of the endogenous network of tonofilaments remains undisturbed during incorporation into tonofilaments. However, microinjection of 1.5-2.0 mg/ml of biotinylated type I results in significant alterations in the organization and assembly state of the endogenous keratin IF network soon after microinjection. The results of this study are consistent with the existence of a state of equilibrium between keratin subunits and polymerized keratin IF in epithelial cells, and provide further proof that IF are dynamic elements of the cytoskeleton of mammalian cells.
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spelling pubmed-21196052008-05-01 Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo J Cell Biol Articles Keratin intermediate filaments (IF) are obligate heteropolymers containing equal amounts of type I and type II keratin. We have previously shown that microinjected biotinylated type I keratin is rapidly incorporated into endogenous bundles of keratin IF (tonofilaments) of PtK2 cells. In this study we show that the earliest steps in the assembly of keratin subunits into tonofilaments involve the extremely rapid formation of discrete aggregates of microinjected keratin. These are seen as fluorescent spots containing both type I and type II keratins within 1 min post-injection as determined by double label immunofluorescence. These observations suggest that endogenous type II keratin subunits can be rapidly mobilized from their endogenous state to form complexes with the injected type I protein. Furthermore, confocal microscopy and immunogold electron microscopy suggest that the type I-type II keratin spots from in close association with the endogenous keratin IF network. When the biotinylated protein is injected at concentrations of 0.3-0.5 mg/ml, the organization of the endogenous network of tonofilaments remains undisturbed during incorporation into tonofilaments. However, microinjection of 1.5-2.0 mg/ml of biotinylated type I results in significant alterations in the organization and assembly state of the endogenous keratin IF network soon after microinjection. The results of this study are consistent with the existence of a state of equilibrium between keratin subunits and polymerized keratin IF in epithelial cells, and provide further proof that IF are dynamic elements of the cytoskeleton of mammalian cells. The Rockefeller University Press 1993-07-01 /pmc/articles/PMC2119605/ /pubmed/7686161 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title_full Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title_fullStr Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title_full_unstemmed Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title_short Dynamics of keratin assembly: exogenous type I keratin rapidly associates with type II keratin in vivo
title_sort dynamics of keratin assembly: exogenous type i keratin rapidly associates with type ii keratin in vivo
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119605/
https://www.ncbi.nlm.nih.gov/pubmed/7686161