Effects Of LSD1 - Mediated Histone H3K4 Demethylation On Transduction Of Androgen Receptor - Regulated Target Genes

Androgen receptor (AR) is a transcription factor that could regulate the transcription of its target genes and contributes to the progressing of prostate cancer. After the binding with androgen, AR moves into nucleus and binds to a DNA sequence called androgen regulation elements (ARE) and functions its activities. In our research we find the binding of AR initiates a process of demethylation of lysine 4 in histion 3 caused by lysine-specific demethylase 1 (LSD1). The demethylation produces H2O2, which is a kind of Reactive oxygen species (ROS), a kind of harmful constituent which could oxidize guanine and cause the recruitment of 8-oxoguanine-DNA glycosylase-1 (OGG1) and Apurinic/apyrimidinic endonuclease (Apel) on specific regions of chromatin to eliminate the oxidative damage and ensure the process of normal transcription. RNA Polymerase II and Topoisomerase II function in the process as protein cofactor as well.Drugs that restrict oxidation and the produce of ROS could influent the transcription of AR targeted genes:PSA, TMPRSS2, miR-125b2 and miR-133b, in which we forecast miR-133b as an AR targeted gene through bioinformatics analysis in previous study. And silencing of LSD1, OGG1 and Topoisomerase II could also reduce the transcription of AR targeted genes. We examined the up-regulation of LSD1, OGG1, Apel, Topo II and RNAP II bingding to chromatin after the stimulation of DHT through ChIP assay. Moreover, silencing of LSD1 could reduce the binding of OGG1, Topo II and RNAP II to specific regions on chromatin, which demonstrate LSD1-initiated demethylation promotes the recruitment of other protein cofactors and the transcription of AR targeted genes. Considering different protein cofactors might bind on different enhancers of chromatin and the space distance is long, those cofactors could not combine with each other in regular circumstances. Oxidation causes the formation of temporary space structure——gene loop and close the space distance to initiate the transcription complex, and we detect the gene loop by Chromosome Conformation Capture assay.In general, our data suggest that in AR signaling pathway, LSD1-initiated demethylation of H3K4 causes oxidation of DNA and produce ROS; BER repair enzymes such as OGG1 and Apel are recruited to eliminate the damage; temporary gene loop occurs to close the space distance and assist the formation of transcription complex contains LSD1, OGG1, Ape1, Topo Ⅱ, RNAP Ⅱ and other cofactors. In the whole model, AR recruits LSD1 on specific regions of chromatin, LSD1 initiates the demethylation of H3K4 and recruits OGG1 and Apel to eliminate oxidative damage. We conclude that demethylation, oxidation of DNA, repair of oxidative damage, and formation of temporary gene loop are all necessary in the process of transcription of AR targeted miR-125b2 and miR-133b. And our data further confirm miR-133b is a direct targeted gene of AR. Those epigenetics conclusion offer a new view in AR related research and could contribute new ideas in the depravation of prostate cancer.