Transcriptional activity of the SHP-1 gene in MCF7 cells is differentiallyregulated by binding of NF-Y factor to two distinct CCAAT-elements

Our previous studies have shown that SHP-1, a SH2 domain-containing protein -tyrosine phosphatase, is expressed not only in cells of hematopoietic line ages, but also in many non-hematopoietic cells under the control of an alte rnative tissue-specific promoter, pi. In this study, the activity of the P1 promoter was analyzed in a region spanning 3.5 kb upstream of the major tr anscription start site in nonhematopoietic MCF-7 cells. Using DNA footprint ing, gel retardation assays and mutational analysis, we have characterized cis-regulatory elements that are essential to confer the pi promoter activi ty. An upstream Spl element (-126 to -118) positively regulated this TATA-b ox-lacking promoter. Two inverted CCAAT-elements (-332 to -328 and -66 to - 62) played important roles in regulating the SHP-1 gene expression, and tra nscription factor NF-Y predominantly bound to the two CCAAT-elements. Bindi ng of NF-Y to the distal CCAAT element enhanced the transcriptional activit y of the P1 promoter. In contrast, binding of NF-Y to the proximal CCAAT-el ement and interacting with repressor(s) inhibited the promoter activity. Fu rthermore, incubation of MCF7 cells with 100 ng/ml trichostatin A, an inhib itor of histone deacetylase, significantly increased the activity of the P1 promoter. Mutation in the proximal CCAAT-element, however, eliminated the activating effect of trichostatin A on the promoter. Together, our data sug gest that NF-Y factor can function either as a specific positive or negativ e regulator of P1 promoter activity in non-hematopoietic MCF7 cells. (C) 20 01 Elsevier Science B.V. All rights reserved.