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Beta1 integrin-mediated adhesion between renal tubular cells after anoxic injury
W Lieberthal1, J B McKenney, C R Kiefer
1Renal Section, Boston University Medical Center Hospital, MA 02118, USA.
Abstract:
beta 1 integrin-mediated adhesion between renal tubular cells after anoxic injury. This study examined the effect of sublethal injury, induced by ATP depletion (5 mM cyanide in the absence of dextrose), on the distribution and function of beta 1 integrins in primary cultures of mouse proximal tubular (MPT) cells. It was shown in this study that sublethal injury results in loss of focal contacts present in uninjured MPT cells, and that the beta 1 integrin molecule becomes redistributed to the apical membrane domain of sublethally injured cells. Polystyrene beads coated with Arg-Gly-Asp (RGD)-containing peptide adhere to the surface of sublethally injured MPT cells but not to control, dextrose-treated cells, indicating that the beta 1 integrins present on the apical surface of the cell remain functional. The presence of an excess of free RGD-containing peptide reduces binding of RGD-coated beads to sublethally injured MPT cells by approximately 50%. It was also demonstrated that adherence of MPT cells in suspension to cyanide-treated monolayers is increased more than 300% above adhesion to control, uninjured monolayers. This abnormal cell-cell adhesion is ameliorated by the presence of an excess of RGD-containing peptide and is reversed if cyanide-treated cells are allowed to recover for 1 h. It was concluded that the beta 1 integrin becomes expressed on the apical surface of MPT cells after sublethal injury. These apically expressed integrins remain functional and mediate aberrant adhesion between MPT cells.
Insights
Sublethal injury causes beta 1 integrins to move to the cell surface in mouse proximal tubular cells. These functional integrins mediate abnormal cell-cell adhesion after injury.
Area of Science:
- Cell Biology
- Renal Physiology
- Integrin Signaling
Background:
- Beta 1 integrins are crucial for cell adhesion and signaling in renal tubular cells.
- Anoxic injury can disrupt normal cell function and cell-cell interactions in the kidney.
- Understanding integrin behavior after injury is key to renal tissue repair.
Purpose of the Study:
- To investigate the effect of sublethal anoxic injury on beta 1 integrin distribution and function in mouse proximal tubular cells (MPTCs).
- To determine if beta 1 integrins on injured MPTCs remain functional and mediate cell adhesion.
- To explore the role of these integrins in aberrant cell-cell adhesion following injury.
Main Methods:
- Primary cultures of mouse proximal tubular cells were subjected to sublethal injury using ATP depletion (cyanide).
- Immunofluorescence microscopy was used to assess beta 1 integrin localization.
- Adhesion assays with Arg-Gly-Asp (RGD)-coated beads and cell-cell adhesion studies were performed.
Main Results:
- Sublethal injury led to the loss of focal contacts and redistribution of beta 1 integrins to the apical membrane of MPTCs.
- Functional beta 1 integrins on the apical surface of injured cells mediated adhesion to RGD-coated beads.
- Cell-cell adhesion increased over 300% in injured MPTCs, mediated by apically expressed beta 1 integrins.
Conclusions:
- Beta 1 integrin expression is upregulated on the apical surface of MPTCs following sublethal anoxic injury.
- These apically localized beta 1 integrins are functional and contribute to abnormal cell-cell adhesion.
- Targeting these integrins may offer therapeutic potential for kidney injury.