Hyperthermia effects on the cytoskeleton and on cell morphology

Area of Science:

• Cell Biology
• Biophysics
• Materials Science

Background:

• Erythrocyte membranes exhibit distinct thermal transitions between 50-75°C.
• Spectrin, a key cytoskeletal protein, plays a crucial role in maintaining erythrocyte membrane stability.

Purpose of the Study:

• To investigate the thermal transitions and associated morphological changes in human erythrocyte membranes.
• To explore the impact of heat on cytoskeletal proteins like spectrin, actin, and microtubules.
• To compare heat-induced cellular responses with those caused by other morphology-modifying agents.

Main Methods:

• Observation of thermal transitions in human erythrocyte ghost membranes.
• Analysis of spontaneous cell fragmentation, haemolysis, and microvesiculation.
• Mechanical drawing of cell processes and subsequent heating to observe beading patterns.

Main Results:

• Five thermal transitions observed between 50-75°C, including spectrin denaturation at 50°C, haemolysis at 65°C, and microvesiculation above 70°C.
• Cell fragmentation is linked to surface wave growth, caused by thermal impairment of spectrin's stabilizing function.
• Heating affects actin monomers and filaments, and causes microtubule depolymerization, with effects on associated proteins.

Conclusions:

• Thermal stress induces significant morphological changes in erythrocytes, driven by alterations in cytoskeletal protein stability.
• The observed beading patterns in cell processes under thermal stress are analogous to those induced by cytoskeleton-weakening agents.
• Understanding these thermal responses provides insights into the general behavior of eukaryotic cell cytoskeletons under stress.