CHARACTERIZATION OF THE 5'-FLANKING REGION OF THE GENE FOR THE GAMMA-CHAIN OF HUMAN FIBRINOGEN

The 5'-flanking region of the gene coding for the gamma chain of human fibrinogen was characterized for its promoter activity, Reporter gene studies using chloramphenicol acetyltransferase as the indicator alon g with mutations in the DNA showed that a TATA-like sequence (-20 to - 23 base pairs (bp)), a CAAT-like sequence (-54 to -57 bp), and an upst ream stimulatory factor (USF) binding site (-66 to -77 bp) constitute a minimal promoter that mediates liver-specific expression of the gene . Electrophoretic gel mobility assays and antibody binding studies con firmed the interaction of USF with the binding site. An IL-6 responsiv e element with a sequence of CTGGAA located at -301 to -306 bp was sho wn to be a functional element in the IL-6 response. In contrast to the IL-6 responsive elements in the human alpha- and beta-fibrinogen gene s, the element in the gene for the gamma chain of human fibrinogen was unaffected by the presence or elevated levels of the beta or delta is oforms of the CCAAT/enhancer binding proteins, A negative element with sequence homology to several silencer elements was also identified in the region of -348 to -390 bp of the gene for the gamma chain of huma n fibrinogen. A comparison of the regulatory elements in the genes cod ing for all three chains in fibrinogen is also presented.