In this report, we investigate the protective mechanism of co-enzyme Q10 on chicken primary myocardial cells during heat stress. Morphological observations indicate that addition of co-enzyme Q10 protects myocardial cells from heat stress, reduces the damage of mitochondria and nucleus, and decreases the mean number of vacuolated mitochondria. We have previously shown that co-enzyme Q10 can protect myocardial cells by upregulating the expression of Hsp70. Therefore, signaling pathways involved in this process were explored. No changes of total MAPK protein (P38MAPK, JNK, ERK) expression in the experimental groups were detected, with the exception of total JNK1. Co-enzyme Q10 failed to increase the expression of JNK1 compared to the HS group which was treated with heat stress only. Addition of Q10 upregulated the expression of p-P38MAPK, p-JNK, and p-ERK1. Inhibitors of P38MAPK and JNK, SB203580 and SP600125, respectively, weakened the upregulation of Hsp70 by co-enzyme Q10, indicating that MAPK pathways participate in the Hsp70 upregulation by co-enzyme Q10. Co-enzyme Q10 upregulates the expression of p-MEK3/6 and p-MEK4, but not p-MEK7 during heat stress. Expression of p-PKCα and p-PKCβ1 was also elevated following the addition of co-enzyme Q10 during heat stress, and addition of PKC inhibitors decreased the expression of Hsp70 induced by co-enzyme Q10. This confirms that PKC is also associated with the upregulation of Hsp70. In HS+Q10 group, addition of SP600125 or SB203580 could increase cell apoptosis under heat stress. Our results suggest that co-enzyme Q10 upregulates the expression of Hsp70 during heat stress to protect chicken primary myocardial cells via the PKC-MEK3/4/6-P38MAPK/JNK pathways.
Keywords: Chicken myocardial cells; Co-enzyme Q10; HSP70; Heat stress; MAPK pathways; PKC.