RESUMO
BACKGROUND: The protein kinase C (PKC) family consists of 3 groups of PKCs, namely the conventional PKC (cPKC), atypical PKC and novel PKC.Accumulating studies conducted in recent years have suggested that PKCs may play important roles in the development of cerebral ischemic/hypoxic preconditioning ( I / HPC ).OBJECTIVE: To observe membrane translocation of hypoxia-activated cPKC isoforms(α, βⅠ, βⅡ and γ) at cellular levels in a cell hypoxia model.DESIGN: Randomized block design.SETTING: Department of Neurobiology, College of Basic Medical Sciences,Capital University of Medical Sciences.MATERIALS: The experiment was completed at the Neurobiological Cell Culture Laboratory of Capital University of Medical Sciences in May 2004.Human neuroblastoma cells with the properties of neurons were maintained and passaged in this laboratory.METHODS: The activation of cPKC isoforms under hypoxic condition and changes of cPKCα, βⅠ, βⅡ and γ membrane translocation(an indicator of PKCs activation) in SH-SY5Y neuroblastoma cells in response to hypoxia (1% 02, 5% CO2 and 94% N2) for 0 to 24 hours were observed using SDS-PAGE, Western blotting and immunocytochemistry.MAIN OUTCOME MEASURES: Effect of sustained hypoxia on cPKC membrane translocation in human neuroblastoma cells was observed with SDS-PAGE, cPKC Western blotting, and immunocytochemistry.RESULTS: cPKCα, βⅠ and βⅡ membrane translocation were increased significantly ( P ＜ 0.05 ) in a time-dependent manner in response to hypoxic exposure, and the increase of cPKCβⅠ was more evident( P ＜ 0. 001 ) after 4hours of hypoxic exposure, whereas no cPKCγ was detected in SH-SY5Y neuroblastoma cells either under normoxic or hypoxic condition. The results suggested that all cPKC isoforms, epically cPKCβⅠ, could be activated by sustained hypoxia, and the absence of cPKCγ in SH-SY5Y neuroblastoma cells may be relevant to the loss of specific biological features of the cultured cells.CONCLUSION: Sustained hypoxia activates the isoforms of cPKCα, βⅠ and βⅡ in human neuroblastoma cells and induces their membrane translocation.cPKCγ isoform may not exist in human neuroblastoma cells, or the cells has lost certain biological characteristics.
RESUMO
AIM: To explore the role of cPKCs in the development of cerebral hypoxic preconditioning, the effect of repetitive hypoxia on the level of protein kinases C ?I and ?II (cPKC ?I and ?II ) membrane translocation in the brain of mice was observed. METHODS: The hypoxic preconditioned mouse model was adapted with minor modification from our previous report. The biochemistry techniques of SDS-PAGE and Western blotting were applied to determine the level of cPKC ?I and ?II membrane translocation in cortex and hippocampus of mice. RESULTS: cPKC ?II translocated from the cytosolic fraction to the particulate fraction in response to the repetitive hypoxic exposure (H1-H4) both in hippocampus and cortex of mice, which was regarded as membrane translocation. The significant membrane translocation of cPKC ?II was found in hippocampus of H4 group (173.3%?21.3% vs H0: 100% or H1: 79.5%?10.7%, P0.05, n=8). CONCLUSION: These results suggest that cPKC ?II may play an important role in the development of cerebral hypoxic preconditioning, but the changes of novel and typical PKC isoenzymes are still under investigation.