B. Tiwari et Vk. Parnaik, Identification of altered DNA-protein interactions at the lamin A proximalpromoter in quiescent hepatocytes, CELL MOL B, 45(6), 1999, pp. 865-875
The nuclear lamina of differentiated cells is composed of A-type and B-type
lamins. The expression of the A-type lamins has been shown to be primarily
under transcriptional control in proliferating cells. In order to gain ins
ights into the factors involved in downregulation of the promoter in quiesc
ent cells, we have compared the DNA-protein interactions at the rat lamin A
proximal promoter in fetal (dividing) hepatocytes and adult (quiescent) he
patocytes by DNase I footprinting analysis, electrophoretic mobility shift
assays and UV crosslinking experiments. We have identified proteins from ad
ult hepatocyte nuclear extracts that are bound to sequences within 28 bp do
wnstream of the transcription initiation site (62 and 48 kDa proteins) and
within 20 bp upstream of the initiation site (54 kDa protein), which may fu
nction as transcriptional repressors of the lamin A proximal promoter.