Journal of Neuroscience, Vol 12, 4437-4446, Copyright © 1992 by Society for Neuroscience
Promoter organization and activity of human monoamine oxidase (MAO) A and B genes
QS Zhu, J Grimsby, K Chen and JC Shih
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles 90033.
Monoamine oxidase A and B (MAO A and B) play important roles in the
metabolism of biogenic and dietary amines and are encoded by two genes
derived from a common ancestral gene. The promoter regions for human MAO A
and B genes have been characterized using a series of 5' flanking sequences
linked to a human growth hormone reporter gene. When these constructs were
transfected into NIH3T3, SHSY-5Y, and COS7 cells, the maximal promoter
activity for MAO A was found in a 0.14 kilobase (kb) PvuII/DraII fragment
(A0.14) and in a 0.15 kb PstI/NaeI fragment (B0.15) for MAO B. Both
fragments are GC-rich, contain potential Sp1 binding sites, and are in the
region where the MAO A and B 5' flanking sequences share the highest
identity (approximately 60%). However, the organization of the
transcription elements is distinctly different between these two promoters.
Fragment A0.14 consists of three Sp1 elements, all in reversed
orientations, and lacks a TATA box. Two of the Sp1 sites are located within
the downstream 90 base pair (bp) direct repeat, and the third is located at
the 3' end of the upstream 90 bp direct repeat. Fragment B0.15 contains an
Sp1-CACCC-Sp1-TATA structure; deletion of any of these elements reduced
promoter activity. Additional Sp1 sites, CACCC elements, CCAAT boxes, and
direct repeats (four 30 bp direct repeats in MAO A and two 29 bp direct
repeats in MAO B) are found in farther-upstream sequences of both genes
(1.27 kb for MAO A and mostly in 0.2 kb for MAO B). Inclusion of these
sequences decreased promoter activity. The different promoter organization
of MAO A and B genes provides the basis for their different tissue- and
cell- specific expression.