Analyses Of Regulation Mechanisms And Roles Of The HIF-1α And SDF-1α/CXCR4in Astrocytes During Hypoxia Stress

Objective:To investigate the pathway and the role of the regulatory mechanism of hypoxiainducible factor-1α(HIF-1α) and stromal cell derived factor1α/chemokine receptor4(SDF-la/CXCR4) in astrocytes model during hypoxia stress.Methods:SD rat astrocytes were cultured and purificated. The astrocytes were randomly divided into three groups, hypoxia group(group A, n=6), siRNA positive group by treated with hypoxia (group B, n=6), siRNA negative group by treated with hypoxia (group C, n=6). Group A were induced to hypoxia by cultured with CoCl2final concentration of50μmol/L. Group B, SD rat astrocytes were transfected siRNA constructor in order to silent HIF-la gene, and then induced to hypoxia by cultured with CoCl2final concentration of50μmol/L. Group C, the astrocytes were transfected negative vector, and then were induced to hypoxia with the same method above. The hypoxia induction in all of groups were analysed for various lengths of time, Oh (T1)、4h (T2)、16h (T3)、24h (T4)、36h (T5). To detect the HIF-la and SDF-1a mRNA expression by using RT-PCR, At the same time to measure the SDF-1a secretion by using the ELISA. All date were analysed by the SPSS17.0software.Results:The astrocytes hypoxia model and HIF-la gene siRNA vector were successfully constructed. This study showed that the mRNA expression of HIF-la and SDF-la were increased in group A and group C for any lengths of experimental time in the cobalt chloride hypoxia environment in contrast with T1(P<0.05). On the other hand, the mRNA expression levels of HIF-1a and SDF-1a showed no significant change in group B for any lengths of experimental time (P>0.05). There was significant difference between group A and group B (P<0.05), also group B and group C (P<0.05), however there was no significant difference between group A compared with group C(P>0.05). On the other hand, the expression of SDF-1protein were raised in group A and group C for any lengths of treatment time in the chemical hypoxia in contrast with T1(P<0.05). But there was no significant difference of SDF-1protein expression among any lengths of treatment time in group B in contrast with T1(P>0.05). There was significant difference between group A and group B (P<0.05), also group B and group C (P<0.05), however there was no significant difference between group A compared with group C(P>0.05).Conclusion:This study indentified HIF-1α and SDF-1α/CXCR4play an important regulatory role in neural cells during hypoxia stress. It is via up-regulation expression of HIF-1α that the up-regulation expression of SDF-1α induced by hypoxia in the astrocytes.