Zinc Finger And BTB Domain Containing Protein 5 (ZBTB5)

ZBTB5 expression is higher in retinoblastoma and muscle cancer tissues. ZBTB5 is a potent transcription repressor of cell cycle arrest gene p21 and a potential proto-oncogene stimulating cell proliferation. Expression of ZBTB5 was greatly induced prior to induction of cell cycle arrest gene p21 when cells were expose to DNA damaging agent, etoposide. ZBTB5 potently activated transcription of p21 gene in the absence of p53. ZBTB5 and Sp1 synergistically activates transcription by acting on the p21 promoter lacking distal p53 binding elements both in the p53 null and p53 positive cells. ZBTB5 increased transcription of p21 in the presence of dominant negative mutant form of p53.ZBTB5 has functional duality in the regulation of cell proliferation and can acts either as oncogene or tumor suppressor depending on presence or absence of functional p53.