The human genome, like other mammalian genomes, encodes numerous natural antisense transcripts (NATs) that have been classified into head-to-head, tail-to-tail, or fully overlapped categories in reference to their sense transcripts. Evidence for NAT-mediated epigenetic silencing of sense transcription remains scanty. The DHRS4 gene encodes a metabolic enzyme and forms a gene cluster with its two immediately downstream homologous genes, DHRS4L2 and DHRS4L1 , generated by gene duplication. We identified a head-to-head NAT of DHRS4 , designated AS1DHRS4, which markedly regulates the expression of these three genes in the DHRS4 gene cluster. By pairing with ongoing sense transcripts, AS1DHRS4 not only mediates deacetylation of histone H3 and demethylation of H3K4 in cis for the DHRS4 gene, but also interacts physically in trans with the epigenetic modifiers H3K9- and H3K27-specific histone methyltransferases G9a and EZH2, targeting the promoters of the downstream DHRS4L2 and DHRS4L1 genes to induce local repressive H3K9me2 and H3K27me3 histone modifications. Furthermore, AS1DHRS4 induces DNA methylation in the promoter regions of DHRS4L2 by recruiting DNA methyltransferases. This study demonstrates that AS1DHRS4, as a long noncoding RNA, simultaneously controls the chromatin state of each gene within the DHRS4 gene cluster in a discriminative manner. This finding provides an example of transcriptional control over the multiple and highly homologous genes in a tight gene cluster, and may help explain the role of antisense RNAs in the regulation of duplicated genes as the result of genomic evolution.

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BackgroundEsophageal squamous cell carcinoma (ESCC) is a highly aggressive cancer whose underlying molecular mechanisms are poorly understood. The natural antisense transcript (NAT) WRAP53 regulates p53 expression and WRAP53 protein is a component of telomerase. NATs play key roles in carcinogenesis, and although WRAP53 is known to increase cancer cell survival, its role in ESCC clinicopathology is unknown. The aim of this study was to investigate WRAP53 expression in ESCC and to correlate it with clinicopathological characteristics.MethodsWRAP53 mRNA and protein expression was measured by quantitative PCR (qRT-PCR) and western blotting, respectively, in 4 ESSC cells lines and in 45 paired ESCC and non-neoplastic esophageal mucosa tissues. To correlate WRAP53 protein expression with clinicopathological characteristics, immunohistochemistry (IHC) was performed on 134 ESCC and 85 non-neoplastic esophageal mucosa tissues.ResultsExpression of WRAP53 was detected in all ESCC cell lines and was upregulated in the ESCC tissues compared with the corresponding non-neoplastic tissues (P<0.01). More cells expressed WRAP53 protein in the ESCC tissues than in the non-neoplastic tissues (P<0.01). Overexpression of WRAP53 was significantly correlated with tumor infiltration depth (P = 0.000), clinical stage (P = 0.001), and lymph node metastasis (P = 0.025). Wrap53 expression was not correlated with age, gender, or tumor differentiation.ConclusionThis report indicates increased expression of WRAP53 in ESCC and that WRAP53 overexpression is correlated with tumor progression. WRAP53 may play a significant role in ESCC; accordingly, WRAP53 could be a useful biomarker for ESCC.

Low testosterone has been inversely associated with hypertension. Our objective was to determine the associations between total testosterone (TT), free testosterone (FT), bioavailable testosterone (BioT), sex hormone–binding globulin (SHBG), and hypertension. Two hundred fifty-three men were enrolled in this study. TT and SHBG were measured by chemiluminescent immunoassay, and FT and BioT were calculated. Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg and/or diastolic blood pressure (DBP) ≥90 mm Hg. Our results showed that hypertensive men had higher SHBG levels, and lower FT and BioT, compared to normotensive men. FT and BioT were inversely associated with SBP and DBP after adjusting for covariates (age, smoking, alcohol consumption, and physical activity). Furthermore, there was a significant decrease in the odds ratios for hypertension in the third and fourth quartiles of BioT and FT, compared to the lowest quartile before and after adjusting for covariates. In contrast, the OR for hypertension in the third quartile of SHBG was lower than the highest quartile. Our data show that FT and BioT are inversely correlated with SBP, DBP, and hypertension in men.

BackgroundThe human DHRS4 gene cluster consists of three genes, DHRS4, DHRS4L2 and DHRS4L1. Among them, DHRS4 encodes NADP(H)-dependent retinol dehydrogenase/reductase. In a previous study, we investigated the alternative splicing of DHRS4 and DHRS4L2. DHRS4L1 was added to the gene cluster recently, but little is known about its structure and expression. To reveal the regulatory mechanism of the DHRS4 gene cluster expression, we studied the structure and transcription of DHRS4L1 in the context of the transcriptional behaviors of the human DHRS4 gene cluster. Based on the results of bioinformatics analysis, we propose a possible mechanism for the transcriptional regulation of the human DHRS4 gene cluster.ResultsThe homologous comparison analysis suggests that DHRS4, DHRS4L2 and DHRS4L1 are three homologous genes in human. DHRS4L1 and DHRS4L2 are paralogues of DHRS4, and DHRS4L2 is the most recent member of the DHRS4 gene cluster. In the minus strand of the human DHRS4 gene cluster, a gene transcribed in an antisense direction was found containing a 5' sequence overlapping the region of exon 1 and promoter of DHRS4. By cloning the full length of RNA variants through 5'RACE and 3'RACE, we identified two transcription start sites, within exon a2 and exon 1, of this newly named gene DHRS4L1 using neuroblastoma cell line BE(2)-M17. Analysis of exon composition in the transcripts of DHRS4 gene cluster revealed that exon 1 was absent in all the transcripts initiated from exon a1 of DHRS4L2 and exon a2 of DHRS4L1.ConclusionsAlternatively spliced RNA variants are prevalent in the human DHRS4 gene cluster. Based on the analysis of gene transcripts and bioinformatic prediction, we propose here that antisense transcription may be involved in the transcriptional initiation regulation of DHRS4 and in the posttranscriptional splicing of DHRS4L2 and DRHS4L1 for the homologous identity of DHRS4 gene cluster. Beside the alternative transcriptional start sites, the antisense RNA is novel possible factor serving to remove exon 1 from the transcripts initiated from exon a1 and exon a2.