p21WAF/CIP1/SDI1 is upregulated due to increased mRNA stability during hydroxyurea-induced senescence of human fibroblasts.
Hydoxyurea induces senescence-like growth arrest in normal human fibroblasts. p21(WAF/CIP1/SDI1), a cyclin dependent kinase inhibitor, was found to be upregulated during this growth arrest. Levels of p21(WAF/CIP1/SDI1) protein and mRNA were increased nine-fold by hydroxyurea in these cells. In order to determine whether p21(WAF/CIP1/SDI1) mRNA is increased by hydroxyurea at the transcriptional level, human fibroblast cells were transfected with reporter constructs containing a p21(WAF/CIP1/SDI1) promoter fragment and then treated with hydroxyurea. The luciferase activities in the reporter-transfected fibroblast cells were not increased by hydroxyurea, indicating that p21(WAF/CIP1/SDI1) transcription was not elevated by hydroxyurea. The half-life of the p21(WAF/CIP1/SDI1) mRNA was increased by 2.5-fold but that of p21(WAF/CIP1/SDI1) protein was not. Our results suggest that increased mRNA stability is the major mechanism of p21(WAF/CIP1/SDI1) elevation in the hydroxyurea-induced growth arrest of human fibroblasts.
Kim
Hyun-Seok
HS
Department of Biochemistry, College of Medicine, Hallym University, 1 Okchon-dong, Chuncheon, Gangwon-do 200-702, South Korea.
Yeo
Eui-ju
EJ
Park
Seong-Hoon
SH
Park
Joo-In
JI
Park
Sang-Chul
SC
Shin
Jong-Yeon
JY
Kim
Min-Ju
MJ
Oh
Soo-Jin
SJ
Won
Moo-Ho
MH
Kang
Tae-Chun
TC
Park
Jae-Bong
JB
Kim
Jaebong
J
Kim
Jong-Il
JI
Lee
Hyun-Yong
HY
Lee
Jae-Yong
JY
D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D016922:Cellular Senescence; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D006918:Hydroxyurea / Q000378:metabolism / Q000494:pharmacology*; D008156:Luciferases / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D008156:Luciferases; D006918:Hydroxyurea