Interaction between two different regulatory elements activates the murine alpha A-crystallin gene promoter in explanted lens epithelia.

Previous experiments have indicated that 5' flanking DNA sequences (nucleotides-366 to +46) are capable of regulating the lens-specific transcription of the murine alpha A-crystallin gene. Here we have analyzed these 5' regulatory sequences by transfecting explanted embryonic chicken lens epithelia with different alpha A-crystallin-CAT (chloramphenicol acetyltransferase) hybrid genes (alpha A-crystallin promoter sequences fused to the bacterial CAT gene in the pSVO-CAT expression vector). The results indicated the presence of a proximal (-88 to +46) and a distal (-111 to -88) domain which must interact for promoter function. Deletion experiments showed that the sequence between -88 and -60 was essential for function of the proximal domain in the explanted epithelia. A synthetic oligonucleotide containing the sequence between -111 and -84 activated the proximal domain when placed in either orientation 57 base pairs upstream from position -88 of the alpha A-crystallin-CAT hybrid gene.