The role of Hsp90α in heat-induced apoptosis and cell damage in primary myocardial cell cultures of neonatal rats

Abstract

ABSTRACT. To understand the mechanism underlying the sudden animal death caused by acute heart failure during heat stress, the relationships among the heat-induced pathological changes and apoptosis and the variations in the levels of protective Hsp90α and its mRNA in the heat-stressed primary myocardial cells of neonatal rats in vitro were studied by cytopathological observation, immunoblotting, RT-PCR, and analysis of the related enzymes. After a period of adaptive cell culture, the myocardial cells were immediately exposed to heat stress at 42°C for 10, 20, 40, 60, 120, 240, 360, and 480 min. Levels of creatine kinase increased from the beginning of heat stress, and the cells exposed to heat stress showed acute cellular Hsp90α, heat stress and myocardial cells lesions characterized by vacuolar degeneration and necrosis after 40 min of heat stress, suggesting that the myocardial cells in vitro were obviously stressed and damaged by higher temperature. The levels of cleaved caspase-3 and cytochrome C, which were related to apoptosis, increased significantly after 40 min of heat stress while the Hsp90α protein level significantly decreased. In contrast, after 6 h of exposure to heat stress, the levels of cleaved caspase-3 and cytochrome C decreased while those of Hsp90α significantly increased, suggesting that early depletion of Hsp90α coincides with a high rate of necrosis and apoptosis in heat-stressed myocardial cells, while the Hsp90α level in surviving cells increases again with significantly less apoptosis after 6 h of heat stress. These findings also indicate that apoptosis of myocardial cells occurs through the activation of the cytochrome C and caspase-3 pathway. The cell repair capacity of Hsp90α is overstrained in the early phase of heat treatment and needs some hours to stabilize. As a result, in the primary myocardial cells in vitro, Hsp90α shows protective activity against damage at the end period of the heat exposure.

Apoptosis in response to heat stress is positively associated with heat-shock protein 90 expression in chicken myocardial cellsin vitro

“…Previous studies reported that heat stress could cause severe damage to myocardial cells in rats, accompanied by an increase in apoptotic cells [19]. Heat stress would also induce superfluous ROS production and oxidative damage to cellular proteins and DNA [1627], which was consistent with our results.…”

“…The present study showed that from 1 h of heat stress, chicken primary myocardial cells were seriously injured, as indicated by reduced cell viability, increased cell apoptosis and intracellular ROS levels. The stress damage was more significant after 5 h of heat stress, especially in terms of apoptosis, suggesting that heat stress could induce oxidative stress and related cell apoptosis in vitro , which was in line with the results of Islam et al [19] in heat-stressed rat primary myocardial cells. There was a strong negative correlation between Hsp90 expression and ROS level/cell apoptosis; namely, high expression of Hsp90 increased anti-stress capacity [1619].…”

Cloning and expression analysis of a heat shock protein 90 β isoform gene from the gills of Wuchang bream (Megalobrama amblycephala Yih) subjected to nitrite stress

“…Second, oxidative stress is an important factor for inducing apoptosis in various cells (Orrenius, 2007); due to their cytoprotective role, HSPs inhibit key steps in the apoptotic cascade and maintain the physiological homeostasis of the cells. This is possible since apoptosis has been shown to trigger the induction of HSP90 Islam et al, 2013). These facts suggest that HSP90 is a gene that is sensitive to nitrite stress and participates in the regulation of the adaptive responses, similar to its role in responses to other environmental stresses.…”

Role of dynamin‐related protein 1‐mediated mitochondrial fission in resistance of mouse C2C12 myoblasts to heat injury

“…In general, acute exposure to very high temperatures can cause apoptotic damage in muscle cells (Islam et al . ) and muscle injury in animals (Abdelnasir et al . ), whereas frequent exposures to moderately high temperatures or heat acclimation (HA) may protect muscle cells against a subsequent severe heat insult (Monastyrskaya et al .…”

“…Exposure to a temperature above the physiological range can produce both detrimental and beneficial effects on muscle health. In general, acute exposure to very high temperatures can cause apoptotic damage in muscle cells (Islam et al 2013) and muscle injury in animals (Abdelnasir et al 2014), whereas frequent exposures to moderately high temperatures or heat acclimation (HA) may protect muscle cells against a subsequent severe heat insult (Monastyrskaya et al 2003;Liu & Brooks, 2012). In fact, HA has also been tested for cross-tolerance or protection against other pathological conditions (Horowitz et al 2015).…”