Clusterin activates the heat shock response via the PI3K/Akt pathway to protect cardiomyocytes from high-temperature-induced apoptosis.

High temperature (HT) is a common symptom of infectious myocarditis. This study investigates the effects of HT on the heat shock response (HSR) and apoptosis in cardiomyocytes, with the aim of providing insights into potential treatment strategies for myocarditis. Rat cardiomyocytes (H9c2 cells) were exposed to 42°C for 1 h, followed by a return to 37°C to simulate high fever conditions. The cells were divided into seven groups: control, oe-NC, oe-CLU, HT, HT + oe-NC, HT + oe-CLU, and HT + oe-CLU + LY294002 (PI3K inhibitor). Protein levels of HSP70, HSP90, Bax, Bcl2, CLU, p-PI3K, and p-Akt were measured by Western blot, while mRNA expression of HSP70, HSP90, Bax, Bcl2, and CLU was assessed via reverse transcription quantitative polymerase chain reaction. Cell proliferation (cell counting kit-8 assay), apoptosis (flow cytometry), and reactive oxygen species (ROS) levels (MitoSOX assay) were also evaluated. HT exposure led to decreased cell proliferation, increased apoptosis, and elevated ROS levels (p < 0.001), while also inducing expression of HSP70 and HSP90 (p < 0.0001). Overexpression of Clusterin (CLU) enhanced HSP70 and HSP90 levels, reduced apoptosis, improved cell proliferation, and decreased ROS under HT conditions (p < 0.0001). The PI3K inhibitor reversed these protective effects, confirming the involvement of the PI3K/Akt pathway (p < 0.05). CLU activates the PI3K/Akt pathway, thereby enhancing the HSR and protecting cardiomyocytes. These findings suggest that CLU could be a potential therapeutic target for myocarditis treatment.