Role of annexin II in reorganization of cytoskeleton in lung type II cells / by Taran K. Singh.
| Author/creator | Singh, Taran K. author. |
| Other author | Liu, Lin, degree supervisor. |
| Other author | Kalmus, Gerhard W., degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 1999. |
| Description | 88 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The lung type II cells synthesize and secrete pulmonary surfactant that functions to maintain mechanical stability of alveoli. Secretion of lung surfactant requires the movement of lamellar bodies, the secretory granules of type II cells, to the plasma membranes through a cytoskeletal barrier at the cell cortex. Disassembly of the cytoskeleton is necessary to allow lamellar bodies access to the plasma membrane following stimulation of type II cells. Annexin II tetramer (Allt) is a member of the Ca²⁺- dependent phospholipid - binding protein family, and has been shown to bundle or sever actin filament in vitro. It was therefore hypothesized that Allt may facilitate reorganization of the cytoskeleton in type II cells during surfactant secretion. Stimulation of A549 cells, a lung epithelium-derived cell line, with terbutaline caused a transient disassembly of F-actin as determined by the DNase I inhibition assay and staining with Oregon Green 488 Phalloidin. A similar result of also observed in primary culture of lung type II cells. Western blot analysis using anti-actin and anti-annexin II antibodies showed a transient increase of G-actin and annexin II in the soluble fraction of terbutaline-stimulated type II cells. Furthermore, introduction of exogenous Allt in the presence of Ca²⁺ and MgATP into permeabilized type II cells caused a significant disruption in the cortical actin. Phorbol 12-myristate 13-acetate, an activator of protein kinase C, also decreased cortical fluorescence staining in type II cells by phalloidin. Treatment of type 11 cells with A-ethylmaleimide (NEM), a sulfhydryl reagent, resulted in a disruption of the cortical actin. In vitro experiments demonstrated that incubation of Allt with NEM inhibited Allt's F-actin bundling activity without affecting its F-actin binding activity. Therefore, NEM may interfere with Allt's ability to bundle F-actin and thus lead to disassembly of the cortical F-actin in type II cells. NEM also inhibited liposome aggregation mediated by Allt, but not by other annexins. The results above suggest that cytoskeleton undergoes reorganization in the stimulated type II cells and Allt plays a role in this process. Information coming out from this study may be helpful in designing therapies for pulmonary diseases, such as respiratory distress syndrome (RDS) in premature infants and adults. |
| General note | Submitted to the faculty of the Department of Biology. |
| General note | Advisor: Lin Liu |
| General note | Advisor: Gerhard W. Kalmus |
| Dissertation note | M.S. East Carolina University 1999 |
| Bibliography note | Includes bibliographical references (leaves 78-88). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |