The expression and role of integrin-linked kinase in neonatal rats after hypoxia-ischemia brain damage / 临床儿科杂志

ABSTRACT

Objective To investigate the possible function of integrin-linked kinase (ILK)/protein kinase B (PKB/Akt) signaling in repair of neonatal rat hypoxia-ischemia brain damage (HIBD). Methods Postnatal day 10 SD rats were randomly divided into hypoxia ischemia (HI) group and sham control group. Rat brains were collected at 0 h, 4 h, 6 h, 12 h, 24 h, 48 h and 72 h after hypoxia ischemia damage. Immunolfuorescence staining was used to observe the distribution and expression of ILK. Western blot was used to detect the expression of ILK, Akt, phosphorylated Akt (p-Akt) and vascular endothelial growth factor (VEGF). Lentiviral vectors expressing ILK shRNA were constructed to inhibit the expression of ILK in neonatal rats. After intracerebroventricular injections of LV-ILK shRNA lentivirus and LV-control respectively, HIBD model was established. Rat brains were collected at 4 h and 24 h after HIBD. Western blot was used to detect the expression of ILK, p-Akt, and VEGF. TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining was used to detect cell apoptosis. Results Immunolfuorescence staining showed that ILK was widely distributed in cortex and hippocampus both in HI group and sham control group. ILK located at cell membrane and cytoplasm. Western blot results demonstrated that ILK protein increased after HI, with a peak at 24 h, and maintained higher level than those in sham control group. The p-Akt protein signiifcantly increased at 4 h after HI, and signiifcantly decreased in the following 24 h, and then increased again, with a peak at 48 h, but the level of p-Akt protein was higher than that of sham control group. The VEGF protein increased at 4 h after HI, with a peak at 12 h, higher than that of sham control group. The expression of Akt protein showed no signiifcant difference between HI group and sham control group. Lentiviral vectors containing RNAi targeting ILK was applied successfully in vivo. At 4 h and 24 h after HIBD model, the expression of ILK, p-Akt, and VEGF proteins in right side brain received LV-ILK shRNA signiifcantly decreased compared with those of right side brain received LV-control at the same time point. And cell apoptosis signiifcantly increased in LV-ILK shRNA group. Conclusions The expression of ILK, p-Akt, VEGF proteins increased after HI. By inhibiting the expression of ILK, the expression of p-Akt and VEGF proteins can be reduced, and cell apoptosis could increase in newborn rats after HIBD. The results suggest that ILK may induce the expression of VEGF through activating the PI3K/Akt signaling pathway, and promote cell survival and angiogenesis after HIBD.