Fetal Alz-50 clone 1, a novel zinc finger protein, binds a specific DNA sequence and acts as a transcriptional regulator

Fetal Alz-50 clone 1 (FAC1) is a novel, developmentally regulated gene that exhibits changes in protein expression and subcellular localization during neuronal development and neurodegeneration, To understand the functional i mplications of altered subcellular localization, we have established a norm al cellular function of FAC1, The FAC1 amino acid sequence contains regiona l homology to transcriptional regulators. Using the polymerase chain reacti on-assisted binding site selection assay, we have identified a DNA sequence recognized by recombinant FAC1, Mutation of any 2 adjacent base pairs in t he identified binding site dramatically reduced the binding preference of F AC1, demonstrating that the binding is specific for the identified site. Nu clear extracts from neural and non-neural cell lines contained a DNA-bindin g activity with similar specificity and nucleotide requirements as the reco mbinant FAC1 protein, This DNA-binding activity can be attributed to FAC1 s ince it is dependent upon the presence of FAC1 and behaves identically on a nondenaturing polyacrylamide gel as transiently transfected FAC1. In NIH3T 3 cells, luciferase reporter plasmids containing the identified binding sit e (CACAACAC) were repressed by cotransfected FAC1 whether the binding site was proximal or distal to the transcription initiation site. This study ind icates that FAC1 is a DNA-binding protein that functions as a transcription factor when localized to the nucleus.