Distinct chromatin structures at the monoamine oxidase-A promoter correlate with allele-specific expression in SH-SY5Y cells.

M Manca,C Murgatroyd,P Myers,J P Quinn,V J Bubb,J Hill,A Pickles,V Pessoa,H Sharp

doi:10.1111/gbb.12483

Abstract

Monoamine oxidase‐A (MAOA) metabolises monoamines and is implicated in the pathophysiology of psychiatric disorders. A polymorphic repetitive DNA domain, termed the uVNTR (upstream variable number tandem repeat), located at the promoter of the MAOA gene is a risk factor for many of these disorders. MAOA is on the X chromosome suggesting gender could play a role in regulation. We analysed MAOA regulation in the human female cell line, SH‐SY5Y, which is polymorphic for the uVNTR. This heterozygosity allowed us to correlate allele‐specific gene expression with allele‐specific transcription factor binding and epigenetic marks for MAOA. Gene regulation was analysed under basal conditions and in response to the mood stabiliser sodium valproate. Both alleles were transcriptionally active under basal growth conditions; however, the alleles showed distinct transcription factor binding and epigenetic marks at their respective promoters. Exposure of the cells to sodium valproate resulted in differential allelic expression which correlated with allele‐specific changes in distinct transcription factor binding and epigenetic marks at the region encompassing the uVNTR. Biochemically our model for MAOA promoter function has implications for gender differences in gene × environment responses in which the uVNTR has been implicated as a genetic risk.

Highlights

Using chromatin immunoprecipitation (ChIP) analysis in SH-SY5Y cells we show that each allele can support distinct transcription factor, histone-binding and methylation patterns
The situation is more complex in females for several reasons including (1) gene dosage, (2) the potential for Monoamine oxidase-A (MAOA) to escape X-inactivation and (3) heterozygosity of the uVNTR whose genotype might direct distinct MAOA gene expression patterns
We investigated the molecular mechanisms underlying MAOA expression in the human neuroblastoma cell line SH-SY5Y which is both female and heterozygous for the uVNTR

Summary

| INTRODUCTION

Represent either a risk or a protective factor depending on the disorder studied.[4,5,6,7,8,9,10,11] It is thought that the uVNTR acts as a classical tran-. This problem is made more difficult as the MAOA locus has been proposed as one of the loci that can escape X inactivation.[12,13,14] To address the mechanisms which might underpin allele expression in the female we took advantage of the human neuroblastoma-derived SH-SY5Y cell line which has a female karyotype and is heterozygous for the uVNTR This heterozygosity of the uVNTR allows us to distinguish allelic-specific differences in epigenetic marks and transcription factor binding to the DNA encompassing the uVNTR in addition to identification of allele-specific expression directed by the most 50 TSS. The pattern of factor binding and methylation over each allele was correlated with a switch in allele-specific gene expression in response to sodium valproate in SHSY5Y cells

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION