p53 acts as a co-repressor to regulate keratin 14 expression during epidermal cell differentiation.
During epidermal cell differentiation, keratin 14 (K14) expression is down-regulated, p53 expression varies, and the expression of the p53 target genes, p21 and 14-3-3σ, increases. These trends suggest that the relative transcriptional activity of p53 is increased during epidermal cell differentiation. To determine the relationship between K14 and p53, we constructed K14 promoters of various sizes and found that wild-type p53 could repress the promoter activity of all of the K14 promoter constructs in H1299 cells. K14-p160 contains an SP1 binding site mutation that prevents p53 from repressing K14 expression. Using a DNA affinity precipitation assay, we confirmed that p53 forms a complex with SP1 at the SP1 binding site between nucleotides -48 and -43 on the K14 promoter. Thus, our data indicate that p53 acts as a co-repressor to down-regulate K14 expression by binding to SP1. Next, we used a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced epidermal cell differentiation model to examine the inhibition of K14 expression caused by increased p53 activity. Human ovarian teratocarcinoma C9 cells were treated with TPA to induce differentiation. Over-expression of the dominant negative p53 mutant ΔTAp53, which inhibits p53 activity, prevented the TPA-induced K14 down-regulation in C9 cells. Furthermore, treatment of normal primary human foreskin keratinocytes (PHFK) with the p53 inhibitor pifithrin-α (PFT-α) showed that the inhibition of p53 activity relieves K14 repression during epidermal cell differentiation. Finally, we found that TPA induces the phosphorylation of p53 at residue 378, which enhances the affinity of p53 to bind to Sp1 and repress K14 expression.
Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Bi-He
BH
Cai
Pei-Ching
PC
Hsu
I-Lun
IL
Hsin
Chung-Faye
CF
Chao
Mei-Hua
MH
Lu
Hwang-Chi
HC
Lin
Shih-Hwa
SH
Chiou
Pao-Luh
PL
Tao
Jang-Yi
JY
Chen
D020029:Base Pairing / Q000235:genetics; D001483:Base Sequence; D052160:Benzothiazoles / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002478:Cells, Cultured; D056970:Co-Repressor Proteins / Q000378:metabolism*; D000078404:Epidermal Cells; D052816:Foreskin / Q000166:cytology; D005786:Gene Expression Regulation / Q000187:drug effects; D005799:Genes, Dominant / Q000235:genetics; D006801:Humans; D053547:Keratin-14 / Q000235:genetics* / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D052160:Benzothiazoles; D056970:Co-Repressor Proteins; C507540:KRT14 protein, human; D053547:Keratin-14; D050505:Mutant Proteins; D016329:Sp1 Transcription Factor; D016159:Tumor Suppressor Protein p53; D014050:Toluene; C121565:pifithrin; D013755:Tetradecanoylphorbol Acetate