Overexpression of TLR2 and TLR4 susceptibility to serum deprivation-induced apoptosis in CHO cells.
We examined the effect of overexpression of TLR2 and TLR4 on apoptosis. TLR2 and TLR4 transfected CHO cells were subjected to serum deprivation for 0, 24, and 48 h. CHO cells served as control. The survival was 80.4% and 66.8% in CHO cells, 73.8% and 47.6% in TLR2/CHO, and 70.5% and 53.0% in TLR4/CHO, respectively. Flow cytometry examination suggested that apoptotic cells were 7.17% and 32.91% in control CHO cells, 29.0% and 64.6% in TLR2/CHO, and 41.4% and 64.6% in TLR4/CHO, respectively. The levels of FasL and caspase-8 activity in TLR2/CHO and TLR4/CHO cells were significantly higher than that of CHO cells. Transfection of dominant negative FADD into TLR2/CHO and TLR4/CHO cells significantly reduced apoptosis. Our results suggest that overexpression of TLR2 and TLR4 in CHO cells sensitizes the cells to serum deprivation-induced apoptosis and that the mechanisms are involved in the death receptor-mediated signaling pathway.
Fan
Wei
W
Department of Surgery, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
Ha
Tuanzhu
T
Li
Yan
Y
Ozment-Skelton
Tammy
T
Williams
David L
DL
Kelley
Jim
J
Browder
I William
IW
Li
Chuanfu
C
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016466:CHO Cells; D018929:Cell Culture Techniques / Q000379:methods; D002470:Cell Survival / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D053200:Fas-Associated Death Domain Protein; D005786:Gene Expression Regulation / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D044967:Serum / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D011994:Recombinant Proteins; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4