Binding of nuclear proteins to promoter elements of the mouse alpha A-crystallin gene.

We have investigated the binding of nuclear proteins from the embryonic chicken lens to synthetic oligonucleotides derived from sequence -111/-55 of the murine alpha A-crystallin gene. These sequences were shown previously to consist of a distal (-111/-88) and a proximal (-88/-60) region which are required for expression of this gene (Chepelinsky, A. B., Sommer, B., and Piatigorsky, J. (1987) Mol. Cell. Biol. 7, 1807-1814). Here we use gel retardation and methylation interference experiments to provide evidence for selective binding of different nuclear proteins to oligonucleotides containing sequences -111/-84, -83/-55, and -111/-55. Similar (although not necessarily identical) proteins were found in nuclear extracts of chicken erythrocytes and HeLa cells. Despite this fact, the alpha A-crystallin promoter (-111/+46) did not function in transfected HeLa cells; moreover, deletion experiments showed that only the TATA box is required for activity of this promoter in a HeLa whole cell extract, the distal (-111/84) and proximal (-83/-55) elements having no positive effect on transcription in the HeLa cell extract. These experiments support the idea that the same or related nuclear proteins found in many tissues are necessary but not sufficient for expression of the murine alpha A-crystallin gene.