IN-VIVO SEARCH FOR BUTYRATE RESPONSIVE SEQUENCES USING TRANSGENIC MICE CARRYING (A)GAMMA GENE PROMOTER MUTANTS

We describe an in vivo approach, in transgenic mice, aimed to identify promoter elements responsible for the induction of gamma globin expre ssion by butyrate. Transgenic lines carrying human (A) gamma gene prom oter truncations at position -141, -201, -382, and -730 (A) gamma were treated with alpha amino butyric acid (alpha ABA), and effects on gam ma globin expression were analyzed at the messenger RNA level. No indu ction of gamma gene expression was observed in animals carrying promot ers truncated at positions -141, -201, or -382 (A) gamma, suggesting e ither that butyrate response elements (BRE) are not located in the pro ximal gamma gene promoter or, if they were, they require the cooperati on of upstream sequences for gamma gene induction, Two animals from on e line carrying the -730 (A) gamma truncation responded to alpha ABA t reatment with significant increases in gamma gene expression, indicati ng that a BRE is located between position -382 and -730 region of the (A) gamma gene promoter, Because the maximum induction by alpha ABA is observed in transgenic mice carrying a (A) gamma gene promoter extend ing to nucleotide -1350, it is likely that another butyrate responsive element is located between -730 and -1350 of the (A) gamma gene promo ter, These results indicate that the transgenic mouse model can be use d for identification of DNA regions that contain cis elements involved in gamma globin gene inducibility. (C) 1996 by The American Society o f Hematology.