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KMID : 0361920030330060453
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Korean Journal of Orthodontics
2003 Volume.33 No. 6 p.453 ~ p.463
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Effect of Hypoxia on the Signal Transduction of Apoptosis in Osteobiasts
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Park, Young Joo/박영주
Oh, Soh Taek/Kang, Kyung Hwa/Kim, Sang Cheol/오소택/강경학/김상철
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Abstract
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Mammalian cell is critically dependent on a continuous supply of oxygen. Even brief periods of oxygen deprivation can result in profound cellular damage. The aim of this study was to examine the possible mechanism of apoptosis in response to hypoxia in MC3T3E1 osteoblasts.
MC3T3E1 osteoblasts under hypoxic conditions (2% oxygen) resulted in apoptosis in a time-dependent manner, determined by DNA fragmentation assay and nuclear morphology, stained with fluorescent dye (Hoechst 33258) Pretreatment with Z-VAD-FMK, a pancaspase inhibitor, or Z-DEVI)-CHO, a specific caspase-3 inhibitor, suppressed the DNA ladder in response to hypoxia in a concentrationdependent manner. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase-l activity (YVADase) was detected. To confirm what caspases were involved in apoptosis, western blot analysis was performed using an anticaspase-3 or 6 antibody. The 17-kDa protein, that corresponds to the active products of caspase-3 and the 20-kDa protein of the active protein of caspase-6 were generated in hypoxia-challenged lysates, in which the full length forms of caspase-3 and 6 were evident With a time course similar to caspase-3 and 6 activation, hypoxic stress also caused the cleavage of Lamin A, typical of caspase-6 activity. In addition, the hypoxie, stress elicited the release of cytochrdme c into the cytosol during apoptosis: These findings suggested that the activation of caspases accompanied by a cytochrome c release in response to hypoxia was involved in apoptosc cell death in MC3T3E1 osteoblasts.
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