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Annexins in rat enterocyte and hepatocyte: an immunogold electron-microscope study
J S Weinman1, J M Feinberg, D P Rainteau
1Département de Biochimie, UFR Biomédicale des Saints-Pères, Université René Descartes, Paris, France.
Cell and Tissue Research
|November 1, 1994
Summary
This study reveals the location of annexins in rat intestine and liver cells using immunogold labeling. Annexins are associated with cell membranes and cytoskeletal proteins, suggesting roles in exocytosis and endocytosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Annexins are a family of calcium-dependent phospholipid-binding proteins.
- Their precise localization and functions within epithelial cells remain incompletely understood.
- Previous studies suggest roles in membrane trafficking and cytoskeletal organization.
Purpose of the Study:
- To investigate the ultrastructural localization of annexins II, IV, and VI in rat enterocytes and hepatocytes.
- To elucidate the potential functions of these annexins based on their cellular distribution.
- To explore the relationship between annexin localization and cellular processes like exocytosis and endocytosis.
Main Methods:
- Immunogold labeling of ultrathin sections of rat small intestine and liver.
- Transmission electron microscopy to visualize annexin localization at the ultrastructural level.
Main Results:
- Annexins II, IV, and VI were localized to the microvilli core, rootlets, and plasma membranes in enterocytes.
- Annexin VI was specifically concentrated in hepatocyte microvilli, bile canaliculi, sinusoidal cell surfaces, and the space of Disse.
- Annexin VI was also detected in mitochondria of both cell types.
- Observed localizations suggest calcium-dependent associations with membranes and actin cytoskeleton.
Conclusions:
- The findings support the role of annexins in calcium-dependent membrane-cytoskeletal interactions.
- The distribution of annexins in epithelial cells indicates their involvement in exocytotic and endocytotic processes.
- This study provides ultrastructural evidence for annexin function in cellular transport mechanisms.