Site-specific alteration of actin assembly visualized in living renal epithelial cells during ATP depletion
Autor: | Joel M. Weinberg, Fiona M. Pollock, Dorothy R. Sorenson, Chris A. Edwards, Eric A. Shelden |
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Rok vydání: | 2002 |
Předmět: |
Pathology
medicine.medical_specialty Time Factors Swine Green Fluorescent Proteins Arp2/3 complex macromolecular substances Microfilament Kidney Actin remodeling of neurons Adenosine Triphosphate Reference Values medicine Cell Adhesion Animals Cytoskeleton Actin Focal Adhesions biology Actin remodeling Epithelial Cells General Medicine Actins Cell biology Actin Cytoskeleton Luminescent Proteins Microscopy Electron Profilin Nephrology biology.protein LLC-PK1 Cells Indicators and Reagents MDia1 Protein Processing Post-Translational |
Zdroj: | Journal of the American Society of Nephrology : JASN. 13(11) |
ISSN: | 1046-6673 |
Popis: | Disruption of normal actin organization in renal tubular epithelial cells is an important element of renal injury induced by ischemia. Studies of fixed cells indicate that the cytoskeleton is disrupted by both ischemia and ATP depletion in a site-specific manner. However, few studies have examined these effects in living cells, and the relationship between the time course of ATP reduction and alteration of the cytoskeleton remains unclear. Here, time-lapse video images of cultured renal epithelial cells expressing an enhanced green fluorescent protein (EGFP)-actin fusion protein were obtained, and the kinetics of fluorescence actin distribution before and during ATP depletion is quantified and compared with measured ATP levels. This study found that assembly of lamellar actin is inhibited rapidly as cellular ATP levels are reduced, whereas disruption of actin in stress fibers is more gradual and persis- tent. Actin associated with focal adhesions is largely resistant to ATP depletion in these experiments, and, consistent with previous studies, particulate aggregates of actin were formed within the cytoplasm of ATP-depleted cells. Most surprisingly, time-lapse imaging of EGFP-actin distribution, quantitative fluorescence imaging of phalloidin-stained cells, and ultra- structural studies indicate that assembly of actin filaments occurs at sites of epithelial cell-cell attachment in ATP-de- pleted cells. This assembly is initiated early during ATP de- pletion and continues after ATP levels are maximally reduced. Assembly of actin at sites of cell-cell attachment may be an element of the pathology of injury induced by ischemia, or alternatively, could reflect the function of a protective mech- anism. These studies directly demonstrate site-specific alter- ation of actin assembly in living epithelial cells during ATP depletion. The results also reveal that actin reorganization continues after ATP levels are maximally decreased and that epithelial cell-cell attachments are sites of actin assembly in ATP-depleted cells. |
Databáze: | OpenAIRE |
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