The mouse APLP2 gene: Chromosomal localization and promoter characterization

Senile plaques are primarily comprised of deposits of the β-amyloid protein derived from larger amyloid precursor proteins (APPs). APP is a member of a gene family, including amyloid precursor-like proteins APLP1 and APLP2. Using interspecific mouse backcross mapping, we localized the mouse APLP2 gene to the proximal region of mouse chromosome 9, syntenic with a region of human 11q. We cloned an ∼1.2-kilobase mouse genomic fragment containing the APLP2 gene promoter. The APLP2 promoter lacks a typical TATA box, is GC-rich, and contains several sequences for transcription factor binding. S1 nuclease protection analysis revealed the presence of multiple transcription start sites. The lack of a TATA box, the presence of a high GC content, and multiple transcription start sites place the APLP2 promoter in the class of promoters of "housekeeping genes." Regulatory regions within the promoter were assayed by transfection of mouse N2a and Ltk^- cells with constructs containing progressive 5′-deletions of the APLP2 promoter fused to the bacterial chloramphenicol acetyl transferase (CAT) reporter gene. A minimal region that includes sequences 99 bp upstream of the predominant transcription start site of the APLP2 promoter was sufficient to direct high levels of CAT expression.