| A Nonapoptotic Cell Death Process, Entosis, that Occurs by Cell-in-Cell Invasion Cell, Volume 131, Issue 5, 30 November 2007, Pages 966-979 Michael Overholtzer, Arnaud A. Mailleux, Ghassan Mouneimne, Guillaume Normand, Stuart J. Schnitt, Randall W. King, Edmund S. Cibas and Joan S. Brugge Summary Epithelial cells require attachment to extracellular matrix (ECM) to suppress an apoptotic cell death program termed anoikis. Here we describe a nonapoptotic cell death program in matrix-detached cells that is initiated by a previously unrecognized and unusual process involving the invasion of one cell into another, leading to a transient state in which a live cell is contained within a neighboring host cell. Live internalized cells are either degraded by lysosomal enzymes or released. We term this cell internalization process entosis and present evidence for entosis as a mechanism underlying the commonly observed “cell-in-cell” cytological feature in human cancers. Further we propose that entosis is driven by compaction force associated with adherens junction formation in the absence of integrin engagement and may represent an intrinsic tumor suppression mechanism for cells that are detached from ECM. Summary | Full Text | PDF (3047 kb) |
| The aimless RasGEF is required for processing of chemotactic signals through G-protein-coupled receptors in Dictyostelium Current Biology, Volume 6, Issue 6, 1 June 1996, Pages 719-729 Robert H. Insall, Jane Borleis and Peter N. Devreotes Summary The discovery of the gene adds an interesting new member to the family of RasGEFs. Our data suggest an unforeseen role for a RasGEF, and therefore presumably a complete Ras pathway, in the processing of chemotactic signals through G-protein-coupled receptors. Summary | Full Text | PDF (424 kb) |
| Photoreceptor Current and Photoorientation in Chlamydomonas Mediated by 9-Demethylchlamyrhodopsin Biophysical Journal, Volume 81, Issue 5, 1 November 2001, Pages 2897-2907 Elena G. Govorunova, Oleg A. Sineshchekov, Wolfgang Gärtner, Alexander S. Chunaev and Peter Hegemann Abstract Green flagellates possess rhodopsin-like photoreceptors involved in control of their behavior via generation of photocurrents across the plasma membrane. mutants blocked in retinal biosynthesis are “blind,” but they can be rescued by the addition of exogenous retinoids. Photosignaling by chlamyrhodopsin regenerated with 9-demethylretinal was investigated by recording photocurrents from single cells and cell suspensions, and by measuring phototactic orientation. The addition of a saturating concentration of this analog led to reconstitution of all receptor molecules. However, sensitivity of the photoreceptor current in cells reconstituted with the analog was smaller compared with retinal-reconstituted cells, indicating a decreased signaling efficiency of the analog receptor protein. Suppression of the photoreceptor current in double-flash experiments was smaller and its recovery faster with 9-demethylretinal than with retinal, as it would be expected from a decreased PC amplitude in the analog-reconstituted cells. Cells reconstituted with either retinal or the analog displayed negative phototaxis at low light and switched to positive one upon an increase in stimulus intensity, as opposed to the wild type. The reversal of the phototaxis direction in analog-reconstituted cells was shifted to a higher fluence rate compared with cells reconstituted with retinal, which corresponded to the decreased signaling efficiency of 9-demethylchlamyrhodopsin. Abstract | Full Text | PDF (164 kb) |
Copyright © 1964 The Biophysical Society. All rights reserved.
Biophysical Journal, Volume 4, Issue 6, 441-450, 1 November 1964
doi:10.1016/S0006-3495(64)86794-1
Articles
T.T. Puck, P. Sanders and D. Petersen
A method for life cycle analysis in mammalian cells which utilizes the collection function has been applied to the Chinese hamster ovary grown in suspension. The following durations were found for the various parts of the life cycle: S, 4.13 hours; G1, 4.71 hours; G2, 2.81 hours; mitosis, 0.81 hours. The cell has a total generation time of 12.4 hours as opposed to 20.1 hours for the S3 HeLa cell. However, the relative lengths of each phase of the life cycle are identical within experimental uncertainty in the two cells.