Regulation of Monoamine Oxidase B Gene Expression: Key Roles for Transcription Factors Sp1, Egr1 and CREB, and microRNAs miR-300 and miR-1224

• Published in: Journal of molecular biology 2019-03, Vol.431 (6), p.1127-1147
• Main Authors: Arige, Vikas, Agarwal, Anshu, Khan, Abrar A., Kalyani, Ananthamohan, Natarajan, Bhargavi, Gupta, Vinayak, Reddy, S. Santosh, Barthwal, Manoj K., Mahapatra, Nitish R.
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Binding Sites; Cell Line; Cricetulus; cyclic AMP; Cyclic AMP Response Element-Binding Protein - metabolism; dopamine; Down-Regulation; Early Growth Response Protein 1 - metabolism; Gene Expression Regulation, Enzymologic; Genes, Reporter; Genetic Predisposition to Disease - genetics; Humans; Male; Mice; MicroRNAs - metabolism; Monoamine Oxidase - genetics; Monoamine Oxidase - metabolism; post-transcriptional regulation; Promoter Regions, Genetic; protein kinase A; Rats; Sp1 Transcription Factor - metabolism; Transcription Factors; Transcription, Genetic; transcriptional regulation
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2019.01.042

Monoamine oxidase B (MAO-B), a flavoenzyme located in the outer mitochondrial membrane, is involved in the catabolism of monoamines. Altered levels of MAO-B are associated with cardiovascular/neuronal diseases. However, molecular mechanisms of MAO-B gene regulation are partially understood. We undertook a systematic analysis of the MAO-B gene to identify the key transcriptional/post-transcriptional regulatory molecules. Expression of MAO-B promoter–reporter constructs in cultured cells identified the −144/+25-bp domain as the core promoter region. Stringent in silico analysis of this core promoter predicted binding sites for several transcription factors. Over-expression/down-regulation of transcription factors Sp1/Egr1/CREB increased/decreased the MAO-B promoter–reporter activity and endogenous MAO-B protein level. Electrophoretic mobility shift assays and ChIP assays provided evidence for interactions of Sp1/Egr1/CREB with the MAO-B promoter. MAOB transcript level also positively correlated with the transcript level of Sp1/Egr1/CREB in various human tissue samples. Computational predictions using multiple algorithms coupled with systematic functional analysis revealed direct interactions of the microRNAs miR-1224 and miR-300 with MAO-B 3′-UTR. Dopamine dose-dependently enhanced MAO-B transcript and protein levels via increased binding of CREB to MAO-B promoter and reduced miR-1224/miR-300 levels. 8-Bromo-cAMP and forskolin augmented MAO-B expression, whereas inhibition of PKA diminished the gene expression suggesting involvement of cAMP-PKA axis. Interestingly, Sp1/Egr1/CREB/miR-1224 levels correlate with MAO-B expression in rodent models of hypertension/MPTP-induced neurodegeneration, indicating their roles in governing MAO-B gene expression in these disease states. Taken together, this study elucidates the previously unknown roles of the transcription factors Sp1/Egr1/CREB and microRNAs miR-1224/miR-300 in regulating MAO-B gene expression under basal/disease states involving dysregulated catecholamine levels. [Display omitted] •Aberrant MAO-B expression is associated with cardiovascular/neurological diseases.•We systematically analyzed transcriptional/posttranscriptional regulation of MAO-B.•The transcription factors Sp1, Egr1, and CREB activate MAO-B gene expression.•The microRNAs miR-1224/miR-300 post-transcriptionally down-regulate MAO-B gene.•These findings provide novel insights into mechanisms of catecholamine homeostasis.