| Summary: | 碩士 === 台北醫學院 === 保健營養學研究所 === 85 === Human plasma phospholipid transfer protein (PLTP) was
identified to promote phospholipid transfer from liposomes,
very low density lipoprotein (VLDL) or low density
lipoprotein (LDL) to high density lipoprotein (HDL). PLTP
also plays an important role to facilitate HDL conversion.
However, its physiological function is less known. The
purpose of this study was to investigate the effects of
lipoproteins and insulin on PLTP content and gene
transcription in human hepatoblastoma (HepG2) cells. HepG2 cells
were grown in 90 % MEM (minimum essential medium)
supplemented with 10 % of fetal bovine serum, 1 mM
sodium pyruvate, 50 U/mL penicillin, and 50 ug/ml
streptomycin at 37℃ and in 5 % CO2 atmosphere. Upon 90 %
confluency, the cells were switched to serum-free media
without antibiotics for 24 hours. After 24-hour serum-free
incubation, HDL (50 ug/mL), LDL (50 ug/mL), VLDL (50 ug/
mL) or insulin (1 ug/mL) was added to the media for 12-24 hours.
The control group was without any addition of lipoproteins or
insulin. The conditioned media were collected at 12 and
24 hours for protein analysis. Cells were collected for the
measurements of PLTP content using 10 % SDS-PAGE and
Western blotting, and PLTP mRNA expression using slot blotting.
The results showed that protein secretion into the conditioned
media in LDL, VLDL and insulin treatment groups was
significantly lower than the control group at both 12 and
24 hours (p<0.05). In addition, protein secretion was
significantly increased at 24h than at 12h in all groups
(p<0.05). The cellular PLTP exhibited one major band
with molecular weight of 44.0 kilodaltons (kDa) in
HepG2 cells. The cellular PLTP was not significantly
different among the five groups. The level of PLTP mRNA was
similar among the five groups. In conclusion, lipoproteins
and insulin did not significantly affect PLTP content and gene
transcription in HepG2 cells.
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