R1, a novel repressor of the human monoamine oxidase A.
Monoamine oxidase catalyzes the oxidative deamination of a number of neurotransmitters. A deficiency in monoamine oxidase A results in aggressive behavior in both humans and mice. Studies on the regulation of monoamine oxidase A gene expression have shown that the Sp1 family is important for monoamine oxidase A expression. To search for novel transcription factors, the sequences of three Sp1 sites in the monoamine oxidase A core promoter were used in the yeast one-hybrid system to screen a human cDNA library. A novel repressor, R1 (RAM2), has been cloned. The R1 cDNA encodes a protein with 454 amino acids and an open reading frame at the 5'-end. The transfection of R1 in a human neuroblastoma cell line, SK-N-BE (2)-C, inhibited the monoamine oxidase A promoter and enzymatic activity. The degree of inhibition of monoamine oxidase A by R1 correlated with the level of R1 protein expression. R1 was also found to repress monoamine oxidase A promoter activity within a natural chromatin environment. A gel-shift assay indicated that the endogenous R1 protein in SK-N-BE (2)-C cells interacted with the R1 binding sequence. R1 also bound directly to the natural monoamine oxidase A promoter in vivo as shown by chromatin immunoprecipitation assay. Immunocytochemical analysis showed that R1 was expressed in both cytosol and nucleus, which suggested a role for R1 in transcriptional regulation. Northern blot analysis revealed the presence of endogenous R1 mRNA in human brain and peripheral tissues. Taken together, this study shows that R1 is a novel repressor that inhibits monoamine oxidase A gene expression.
Chen
Kevin
K
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of California, Los Angeles, California 90033, USA.
Ou
Xiao-Ming
XM
Chen
Gao
G
Choi
Si Ho
SH
Shih
Jean C
JC
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002384:Catalysis; D045744:Cell Line, Tumor; D002843:Chromatin / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D008995:Monoamine Oxidase / Q000737:chemistry / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000502:physiology*
D002843:Chromatin; D012097:Repressor Proteins; D008995:Monoamine Oxidase