TISSUE-SPECIFIC AND SPECIES-SPECIFIC PROMOTER ELEMENTS OF RAT GAMMA-CRYSTALLIN GENES

The 5′ flanking regions of the six rat γ-crystallin genes (γA-γF) are all capable of conferring lens-specific expression to the bacterial chioramphenicol acetyl transferase (CAT) reporter gene in either transdifferentiating chicken neural retina cells or mouse lens epithelial cells. Deletion mapping of the moat active γ-crystallin promoter region, the γD region, showed that at least three elements are required for maximal expression in mouse lens epithelial cells: element(s) located between -200 and -106, a conserved CG rich region around position -75, and a CG stretch around -15. The region between -200 and -106 was dispensable in transdifferentiating chicken neural retina cells, which instead required the region between -106 and -78. The maximal activity of the γE and γ promoters was also dependent upon the integrity of the conserved CG region located around -75. A synthetic oligonucleotide containing this sequence was capable of lens-specific enhancement of the activity of the tk promoter in transdifferentiating chicken neural retina cells but not in mouse lens epitheilal cells. Our results further show that this region may contain a silencer element, active in non-lens tissues, as well. © 1990 Oxford University Press.