Spatial distribution of cytoskeleton intermediate filaments during fetal rat hepatocyte differentiation

Vassy, Jany; Irinopoulou, Théano; Beil, Michael; Rigaut, Jean Paul

doi:10.1002/(sici)1097-0029(19971201)39:5<436::aid-jemt6>3.0.co;2-e

Cited by 9 publications

(4 citation statements)

References 81 publications

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“…14 The endodermally derived hepatocyte is the most abundant liver cell type. 15 Adult hepatocytes are somewhat unique among "simple-type" (i.e., single-layered glandular) epithelia in that they express only K8 and K18, whereas enterocytes and other epithelial cells express 2 (or more) type I or type II keratins. Lower vertebrate hepatocytes may express additional poorly characterized type I keratins, and early embryonic hepatoblasts coexpress K19 with K8/18.…”

Section: If Proteins and Their Distribution In The Livermentioning

confidence: 99%

“…In contrast, single GFAP ablation does not significantly affect the IF organization of activated stellate cells, which indicates that desmin partners with vimentin in generating normal filaments in these cells. The functional significance of IF 15 Van Eyken and Desmet, 16 Wisse et al, 54 and Libbrecht et al 55 *In addition, rat cholangiocytes express K20, 56 chicken stellate cells express keratins, 57 rat oval cells also express K14, 58 and rat embryonic liver cells may express desmin. 15 .…”

Section: Animal Studies Point To the Liver And Intestine As Potentialmentioning

confidence: 99%

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Keratins: Guardians of the liver

2002

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Section: If Proteins and Their Distribution In The Livermentioning

confidence: 99%

Section: Animal Studies Point To the Liver And Intestine As Potentialmentioning

confidence: 99%

Keratins: Guardians of the liver

2002

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“…This last limitation can partially be alleviated by using correlative light and electron microscopy, which combines the live-cell capabilities of light microscopy and the superior spatial resolution of EM (Svitkina and Borisy, 1998). Confocal laser scanning microscopy can visualize the three-dimensional organization of cytoskeletal elements in situ (Vassy et al, 1997;Baschong et al, 1999) but makes use of fluorescent dyes that can affect intermolecular interactions and does not measure physical properties. Indeed, visualizing the actin cytoskeleton by fluorescence microscopy does not quantify its organization; e.g., enhanced fluorescence intensity of the F-actin may not necessarily mean enhanced heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Mapping of Live Cells by Multiple-Particle-Tracking Microrheology

Tseng

Kole

Wirtz

2002

Biophysical Journal

379

367

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This paper introduces the method of live-cell multiple-particle-tracking microrheology (MPTM), which quantifies the local mechanical properties of living cells by monitoring the Brownian motion of individual microinjected fluorescent particles. Particle tracking of carboxylated microspheres imbedded in the cytoplasm produce spatial distributions of cytoplasmic compliances and frequency-dependent viscoelastic moduli. Swiss 3T3 fibroblasts are found to behave like a stiff elastic material when subjected to high rates of deformations and like a soft liquid at low rates of deformations. By analyzing the relative contributions of the subcellular compliances to the mean compliance, we find that the cytoplasm is much more mechanically heterogeneous than reconstituted actin filament networks. Carboxylated microspheres embedded in cytoplasm through endocytosis and amine-modified polystyrene microspheres, which are microinjected or endocytosed, often show directed motion and strong nonspecific interactions with cytoplasmic proteins, which prevents computation of local moduli from the microsphere displacements. Using MPTM, we investigate the mechanical function of alpha-actinin in non-muscle cells: alpha-actinin-microinjected cells are stiffer and yet mechanically more heterogeneous than control cells, in agreement with models of reconstituted cross-linked actin filament networks. MPTM is a new type of functional microscopy that can test the local, rate-dependent mechanical and ultrastructural properties of living cells.

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“…In previous work (20)(21)(22), image analysis procedures were defined in order to describe variations of cytokeratin networks in rat hepatocytes during fetal development. These approaches were not designed to discriminate between different patterns inside individual cells.…”

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confidence: 99%

Quantitative analysis of cytokeratin network topology in the MCF7 cell line

et al. 1999

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Background: In the MCF7 human breast cancer cell line, several patterns of cytokeratin networks are observed, depending on the intracellular localization. Our hypothesis is that architectural variations of cytokeratin networks depend on local tensions or forces appearing spontaneously in the cytoplasm. The aim of this work was to discriminate between the different patterns and to quantitate these variations. Materials and Methods: Image analysis procedures were developed to extract cytokeratin filament networks visualized by immunofluorescence and confocal microscopy. Two methods were used to segment sets of curvilinear objects. The first, the ''mesh-approach,'' based on classical methods of mathematical morphology, takes into account global network topology. The second, the ''filamentapproach'' (novel), is meant to account for individual element morphology. These methods and their combination allow the computation of several features at two levels of geometry: global (network topology) and local (filament morphology).Results: Variations in cytokeratin networks are characterized by their connectivity, density, mesh structure, and filament shape. The connectivity and the density of a network describe its location in a local ''stress-force'' zone or in a ''relaxed'' zone. The mesh structure characterizes the intracellular localization of the network. Moreover, the filament shape reflects the intracellular localization and the occurrence of a ''stress-force'' zone. Conclusions: These features permitted the quantitation of differences within the network patterns and within the specific filament shapes according to the intracellular localization. Further experiments on cells submitted to external forces will test the hypothesis that the architectural variations of intermediate filaments reflect intracytoplasmic tensions.

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Spatial distribution of cytoskeleton intermediate filaments during fetal rat hepatocyte differentiation

Cited by 9 publications

References 81 publications

Keratins: Guardians of the liver

Keratins: Guardians of the liver

Micromechanical Mapping of Live Cells by Multiple-Particle-Tracking Microrheology

Quantitative analysis of cytokeratin network topology in the MCF7 cell line

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