HSP27 phosphorylation protects against endothelial barrier dysfunction under burn serum challenge

Area of Science:

• Cell Biology
• Physiology
• Biochemistry

Background:

• Burn injuries cause endothelial barrier dysfunction, leading to lung edema and shock.
• Heat shock protein 27 (HSP27) regulates actin dynamics via phosphorylation.
• The role of HSP27 in burn-related endothelial dysfunction was previously unknown.

Purpose of the Study:

• To investigate the role of HSP27 phosphorylation in burn serum-induced pulmonary endothelial barrier dysfunction.
• To determine if HSP27 phosphorylation acts as a protective mechanism against burn-related endothelial hyperpermeability.

Main Methods:

• Utilized pulmonary endothelial cell monolayers exposed to burn serum.
• Analyzed F-actin rearrangement and HSP27 phosphorylation dynamics.
• Employed overexpression of wild-type, phospho-mimicking (HSP27(Asp)), and non-phosphorylated (HSP27(Ala)) HSP27 mutants.
• Assessed endothelial barrier function and resistance to F-actin depolymerization (Cytochalasin D).

Main Results:

• Burn serum induced F-actin rearrangement and transient HSP27 phosphorylation, preceding hyperpermeability.
• Overexpression of HSP27(Asp) reversed F-actin changes and attenuated hyperpermeability.
• HSP27(Ala) did not confer protection.
• HSP27(Asp) enhanced resistance to Cytochalasin D-induced barrier disruption.
• Phosphatases and sumoylation-inhibited MK2 activity contributed to blunted HSP27 phosphorylation.

Conclusions:

• HSP27 phosphorylation is a protective response against burn serum-induced endothelial barrier dysfunction.
• Targeting HSP27 phosphorylation represents a potential therapeutic strategy for burn-induced lung edema and shock.