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Monensin-dependent and -independent mechanisms of cell-matrix adhesion
Abstract:
Attachment and spreading of human FL cells on a subcellular matrix (SCM) preparation made by treating confluent cell monolayers with deoxycholate are insensitive to the presence of monensin. However, if the cell suspension is surface-iodinated prior to adhesion using the LPO/H2O2 system, cell spreading on SCM is inhibited by 1 microM monensin. The suggested interpretation is that cell surface components required for cell spreading on SCM are inactivated by iodination and need replacement from intracellular reserves by a monensin-sensitive pathway. This pathway is not required in the absence of iodination when sufficient surface components (or a monensin-independent pathway of surface expression) are available. Support for this interpretation is obtained by means of double-iodination experiments in which surface-labelled cells adhere and spread, are detached and labelled a second time and then allowed to adhere again to SCM. Cell spreading in the second case is inhibited by approximately 80%, suggesting that both previously expressed and newly recruited receptors are inactivated.
Insights
Cell spreading on subcellular matrix (SCM) is unaffected by monensin unless cells are iodinated. Iodination inactivates surface components, requiring a monensin-sensitive pathway for replacement from intracellular reserves.
Area of Science:
- Cell Biology
- Biochemistry
Background:
- Cell adhesion and spreading are crucial processes mediated by cell surface components.
- Understanding the regulation of these surface components is vital for cell biology research.
Purpose of the Study:
- To investigate the role of intracellular reserves in cell spreading on subcellular matrix (SCM).
- To determine the effect of surface iodination on cell spreading and its sensitivity to monensin.
Main Methods:
- Human FL cells were cultured and treated to prepare SCM.
- Cells were subjected to surface iodination using the lactoperoxidase/hydrogen peroxide (LPO/H2O2) system.
- Cell adhesion and spreading assays were performed on SCM in the presence or absence of monensin.
- Double-iodination experiments were conducted to assess receptor replenishment.
Main Results:
- Cell attachment and spreading on SCM were insensitive to monensin in untreated cells.
- Surface iodination of cells prior to adhesion inhibited spreading on SCM in a monensin-sensitive manner.
- Double-iodination experiments showed an approximately 80% inhibition of cell spreading, suggesting inactivation of both existing and newly recruited surface receptors.
Conclusions:
- Cell spreading on SCM relies on surface components that can be inactivated by iodination.
- A monensin-sensitive pathway facilitates the replacement of inactivated surface components from intracellular reserves.
- This pathway is essential when surface components are depleted or inactivated, as demonstrated by iodination experiments.