Apoptosis in hypoxic mice influenced by miR-138-siRNAs-HIF-1α and miR- 21-siRNAs-HVCN1

Abstract

Background The complications of intraventricular-cerebral hemorrhage in premature infants are irreversible and epilepsy is common in these infants. Inflammation may cause damage to brain cells by increasing oxygen consumption, intracellular calcium, and acidosis. In an infant with intraventricular hemorrhage (IVH), the increase of HIF-1a and HVCN1can reduce the complication of oxygen consumption and acidosis as well as by decrease of S100B can protect nerve cells from apoptosis and epilepsy through less brain damage. In this study, we investigated apoptosis in hypoxic mice influenced by miR-138-siRNAs-HIF-1a and miR-21-siRNAs-HVCN1. Methods YKL40, HIF-1a, HVCN1, and S100b genes were compared between two groups of preterm infants with and without maternal inflammation on the firth and the third day of birth, and also they were followup up three months later to observe their seizures. Then, we transfected miRNAs into cell lines to detect the changes in YKL40, HIF-1a, HVCN1, and S100b genes expression and nerve cell apoptosis. By using specific siRNAs injected in mice, we increased the expression of HIF-1a and HVCN1 and decreased S100b genes. Changes in gene expression were assessed using real-time PCR, Western blotting, flow cytometry (FCM), and immunohistochemistry (IHC). Results The expression of the HVCN1 gene revealed a strong negative correlation with epilepsy in both groups of newborns (P < 0.001). The expression levels of the S100b, YKL40, and HIF-1a genes were significantly correlated with epilepsy (P < 0.001). By FCM, the apoptotic index (A.I.) was 41.6 ± 3.3 and 34.5 ± 5.2% after transfecting miRNA-431 and miRNA-34a in cell lines, respectively, while the A.I. was 9.6 ± 2.7 and 7.1 ± 4.2% after transfecting miRNA-21 and miRNA-138. By using IHC double-labeling, it was determined that when hypoxic mice received simultaneous injections of miR-138-siRNAs-HIF-1a and miR-21-siRNAs-HVCN1, there was less apoptosis and epilepsy than in the hypoxia group. Conclusions By injecting miR-138-siRNAs-HIF-1a and miR-21-siRNAs-HVCN1 simultaneously into hypoxia mice, we boosted HVCN1 and HIF-1a and decreased S100b, which reduced apoptosis and epilepsy in hypoxic mice.