UPR-induced Vigorous Chaperone-assisted Selective Autophagy In Muscle Fiber During Exhaustive Exercise Was Improved By HIIT

PURPOSE: This research was aimed to probe the alteration of chaperone-assisted selective autophagy (CASA) among the muscle adaptative effect of high intensity interval training (HIIT) against exhaustive exercise-induced unfold protein response (UPR). METHODS: Male Sprague-Dawley rats were separated into three groups: Group C, Group EE and Group HIIT+EE. HIIT was executed for three days, which contains four periods of 10 min each at 28 m/min with intervening periods of rest lasting 10 min in earch day. The exhaustive exercise (25 ~ 28 m/min) was performed 24 h after HIIT. Gastrocnemius were extracted to assess UPR by levels of Bip; CASA by levels of HSP 70, LC 3 and double immunofluorescent labeling of HSP 70 and BAG 3, LC 3 and p 62, LC 3 and LAMP 2. RESULTS: Exhaustive exercise produced a significant increase in UPR-related protein Bip HSP 70, ubiquitinated proteins (1.23 ± 0.08 vs. 1 ± 0.02, 1.35 ± 0.08 vs. 1 ± 0.12, 1.35 ± 0.06 vs. 1 ± 0.08, p < 0.05), and promote the co-localization of HSP 70 and BAG 3 (30.45 ± 2.03 vs. 3.29 ± 0.38 p < 0.05), which accompanied with elevated autophagy-related proteins LC 3II and co-localization of LC 3 and p 62, LC 3 and LAMP 2(1.23 ± 0.07 vs. 1 ± 0.05, 26,52 ± 3.70 vs. 5.78 ± 1.25, 23 ± 6.18 vs. 2 ± 0,63, p < 0.05). High levels of Bip, ubiquitinated proteins, LC 3II (0,86 ± 0.68 vs. 1.23 ± 0.08, 1.1 ± 0.08 vs. 1.35 ± 0.06, 1.01 ± 0.06 vs. 1.23 ± 0.07, p < 0.05) and co-localization of HSP 70 and BAG 3, LC 3 and p 62, LC 3 and LAMP 2 (9.88 ± 1.06 vs. 30.45 ± 2.03, 15.17 ± 2.47 vs. 26,52 ± 3.70, 6.83 ± 1.13 vs. 23 ± 6.18, p < 0.05) induced by exhaustive exercise were significantly mitigated by HIIT. CONCLUSION: Elevated CASA promotes the degradation of UPR-induced protein aggregation during exhaustive exercise; whereas the decrease of vigorous autophagy levels might attribute to the improvement of UPR after HIIT intervention. Supported by National Natural Science Foundation of China(32000829) and Graduate Research and Innovation Projects of Jiangsu Province (KYCX21_1989)