MEMBERS OF THE MAZ FAMILY - A NOVEL CDNA CLONE FOR MAZ FROM HUMAN PANCREATIC-ISLET CELLS

A human recombinant cDNA clone that encoded a zinc-finger protein (Myc -associated zinc-finger protein of human islet; MAZi) was cloned by sc reening a cDNA library prepared from human pancreatic islet cells. The encoded protein showed a high degree of homology to the Myc-associate d zinc-finger protein MAZ (ZF87 or Pur-1). However, differences betwee n the cDNAs for MAZi and MAZ were found in the length of the encoded p olyalanine stretch and in the sequence of the 5'-end leader. MAZi tran scripts were significantly more abundant in rat pancreatic islet carci noma tissue than in normal rat islet cells. Moreover, MAZi protein bou nd specifically to the pyrimidine-rich strand of the CT-element of the c-myc gene in vitro and strongly induced the expression of chloramphe nicol acetyltransferase (CAT) from a c-myc promoter/CAT reporter const ruct in human pancreatic cells. Our results suggest that a distinct me mber of the MAZ family is expressed in human islet cells and enhances the transcriptional activity of the c-myc gene. (C) 1996 Academic Pres s, Inc.