IDENTIFICATION OF NEGATIVE-ACTING AND PROTEIN-BINDING ELEMENTS IN THEMOUSE ALPHA-A-CRYSTALLIN -1556 -1165-REGION/

The mouse alpha A-crystallin-encoding gene (alpha A-cry) is expressed in a highly lens-preferred manner. To date, it has been shown that thi s lens-preferred expression is controlled by four proximal positive-ac ting transcriptional regulatory elements: DE1 (-111/-97), alpha A-CRYB P1 (-66/-57), PE1/TATA (-35/-19) and PE2 (+24/+43). The present study extends our knowledge of mouse alpha A-cry transcriptional regulatory elements to the far upstream region of that gene by demonstrating that the -1556 to -1165 region contains negative-acting sequence elements which function in transfected lens cells derived from mouse, rabbit an d chicken. This is the first negative-acting regulatory region identif ied in mouse alpha A-cry. The -1556 to -1165 region contains sequences similar to repressor/silencer elements identified in other genes, inc luding those highly expressed in the lens, such as the delta 1-crystal lin (delta 1-cry) and vimentin (vim) genes. The -1480 to -1401 region specifically interacts with nuclear proteins isolated from the alpha T N4-1 mouse lens cell line. Contained within this protein-binding regio n and positioned at -1453 to -1444 is a sequence (RS1) similar to the chicken delta 1-cry intron 3 repressor, and which competes for the for mation of -1480 to -1401 DNA-protein complexes. Our findings suggest t hat lens nuclear proteins bind to the mouse alpha A-cry RS1 region. We demonstrate that the chicken delta 1-cry intron repressor binds simil ar nuclear proteins in chicken embryonic lens cells and mouse alpha TN 4-1 lens cells. However, the mouse alpha A-cry RS1 region does not app ear to bind the same protein(s) that bind to the chicken delta 1-cry i ntron repressor, suggesting the existence of a family of silencer prot eins that recognize a similar site in the diverse cry genes.