Abstract The Ten-eleven translocation (TET) family of dioxygenases hydroxylate 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. 5mC provides important epigenetic instructions during development, and its aberrant control is a major contributor to cellular transformation; however TET functions in regulating the epigenome, particularly in cancer, remain largely unknown. We targeted TET1, TET2, and TET3 for siRNA-mediated depletion in pluripotent human embryonic carcinoma cells and examined the impact on 5mC and 5hmC genome-wide localization. TET1, TET2, and TET3 co-regulate 5hmC at many sites, and depletion of only one of the TETs is sufficient to reduce 5hmC at these co-regulated sites, suggesting a functional co-dependence for TETs. Depletion of TET1 and TET2 had the greatest impact on 5hmC levels at high and low CpG density promoters, respectively, indicating that TETs exhibit DNA sequence-based functional specificity. All TETs prevent hypermethylation throughout the genome, especially in CpG island shores, where TET depletion resulted in prolific hypermethylation. Promoter hypermethylation resulting from TET depletion was associated with histone H2AK119 monoubiquitination, DNMT1, and DNMT3B occupancy. Surprisingly, TETs also promote cytosine methylation, as many loci became hypomethylated following TET depletion. Induction of differentiation generally caused 5hmC reduction, except at transcriptionally activated genes, which become enriched for 5hmC. Importantly, genes prone to promoter hypermethylation in cancer become depleted of intragenic 5hmC and 5mC with TET deficiency. This study highlights the multi-dimensional functions of TETs in mediating DNA methylation, hydroxymethylation, and gene expression patterns, and the results reveal that chromatin landscape and DNA sequence composition are regulators of TET function. Citation Format: Emily L. Putiri, Rochelle L. Tiedemann, Jeong-Hyeon Choi, Keith D. Robertson. Dynamics of TET methylcytosine dioxygenases in 5-methylcytosine and 5-hydroxymethylcytosine patterning in human cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2319. doi:10.1158/1538-7445.AM2014-2319
Abstract 2309: Identification of common and unique epigenetic signatures of chronic hepatitis infection and alcohol abuse in human liver disease
Abstract Dysregulation of the intrinsic DNA methylation landscape is a ubiquitous feature of human carcinogenesis, manifested by global hypomethylation and promoter-specific hypermethylation, ultimately resulting in genome instability and tumor suppressor gene silencing, respectively. Alterations in DNA methylation are particularly apparent in hepatocellular carcinoma (HCC) which afflicts roughly 750,000 new patients each year [1]. Indeed, it has been demonstrated that a variety of tumor suppressor genes (e.g. p53, E-cadherin) are hypermethylated and silenced in HCC [2-4]. Importantly, HCC is accompanied by the premalignant stage of cirrhosis in 80% of cases. One major roadblock to understanding the methylome in HCC is the presence of multiple etiologies such as Hepatitis C virus (HCV), Hepatitis B virus (HBV), and chronic alcoholism. Therefore, we performed genome-wide methylation profiling to dissect the methylation patterns of more than 170 primary liver samples to stratify etiologic and stage-specific changes in the DNA methylation landscape. Our results profile the DNA methylation landscape across normal, cirrhotic, and HCC livers in the largest study of its kind to date. We unveil distinct locus-specific and large-scale effects of HCV, HBV, and chronic alcoholism in hepatocarcinogenesis. Furthermore, analysis indicates a specific methylation profile for individual etiologies as well as conserved patterns throughout cirrhosis and hepatocellular carcinoma. Our study demonstrates that each etiology contains potential biomarkers and targets for downstream clinical therapeutics. This study is our first step toward defining the epigenome in cirrhosis and hepatocellular carcinoma and will be combined with future genomic and epimutational data (e.g. transcription, histone modifications, miRNA) to determine the true extent and interplay between epigenetic marks across different stages of liver cancer. Overall, this research has the potential to improve our understanding of epigenetics and result in diagnostic, prognostic, and therapeutic epigenetic signatures in cirrhosis and hepatocellular carcinoma, which are expected to allow for more timely and efficient detection of disease. 1. Jemal, A., et al., Global cancer statistics. CA: a cancer journal for clinicians, 2011. 61(2): p. 69-90. 2. Tischoff, I. and A. Tannapfe, DNA methylation in hepatocellular carcinoma. World journal of gastroenterology : WJG, 2008. 14(11): p. 1741-8. 3. Calvisi, D.F., et al., Mechanistic and prognostic significance of aberrant methylation in the molecular pathogenesis of human hepatocellular carcinoma. The Journal of clinical investigation, 2007. 117(9): p. 2713-22. 4. Lambert, M.P., et al., Aberrant DNA methylation distinguishes hepatocellular carcinoma associated with HBV and HCV infection and alcohol intake. Journal of hepatology, 2011. 54(4): p. 705-15. Citation Format: Ryan A. Hlady, Rochelle Tiedemann, William Puszyk, Chen Liu, Jeong-Hyeon Choi, Keith D. Robertson. Identification of common and unique epigenetic signatures of chronic hepatitis infection and alcohol abuse in human liver disease. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2309. doi:10.1158/1538-7445.AM2014-2309
Abstract 2305: Acute depletion reveals novel co-regulation of DNA methylation at conserved loci by DNMT1 and DNMT3B
Abstract DNA methyltransferases (DNMTs) are responsible for establishing (DNMT3A, 3B, 3L) and maintaining (DNMT1) DNA methylation genome-wide. Aberrant DNA methylation is frequently observed in cancer; however, little is known about how regulation of this modification goes awry. In this study, we aim to understand how DNA methylation is regulated by the DNMTs throughout the genome by identifying specific and broad changes in methylation patterning upon depletion of the DNMTs. We utilize siRNA technology to acutely deplete NCCIT embryonal carcinoma cells of DNMT mRNA (individually and in combination), and then assay the impact on genome-wide DNA methylation patterns using the HumanMethylation450 Bead Chip (450K array). Depletion of DNMT1 (individual/combination) resulted in widespread hypomethylation, most notably in gene bodies, 3′UTRs, and intergenic sequences. DNMT3 knockdown resulted in more specific changes in DNA methylation, but surprisingly, more hypermethylation (predominately in gene bodies) than hypomethylation events occurred. These specific hypermethylation events, particularly in samples with DNMT3B KD, significantly overlapped with sites hypomethylated in DNMT1 KD conditions, indicating a potential cross-regulatory role for DNMT1 and DNMT3B in regulating DNA methylation across gene bodies. To gain a more comprehensive genome-wide view of DNA methylation in the absence of DNMT3B, we performed Methyl-CpG-Binding-Domain(MBD)-seq on DNMT3B KD cells. MBD-seq revealed dynamic changes in methylation with minor hypermethylation in promoters and subtle hypomethylation across gene bodies; however, analysis of only the most significant methylation changes (> 4-fold) revealed that more hypermethylation events occur in intronic sequences, consistent with results obtained using the 450K array. To further investigate the overlap between DNMT1 hypomethylated and DNMT3B hypermethylated sites, we examined DNA methylation in HCT116 colorectal carcinoma cells lacking (KO) or over-expressing (KI) DNMT1/DNMT3B. Interestingly, a marked number of CpG sites that gained methylation in the DNMT3B KO overlapped significantly with sites that became hypermethylated in DNMT1 and DNMT3B KI, and hypomethylated in DNMT1 KO. Additionally, these HCT116 hypermethylated CpG sites gained methylation in NCCIT DNMT3B KD (individual/combination) and lost methylation in DNMT1 KD. Taken together, these results suggest that DNMT1 and DNMT3B co-regulate DNA methylation at conserved loci across cell types in an opposing fashion, providing novel insight into a potential regulatory mechanism for DNA methylation patterning. Further elucidation of this DNMT1 and DNMT3B co-regulation holds the potential to yield novel therapeutic strategies for correcting aberrant methylation events in cancer. Citation Format: Rochelle Tiedemann, Jeong-Hyeon Choi, Keith Robertson. Acute depletion reveals novel co-regulation of DNA methylation at conserved loci by DNMT1 and DNMT3B. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2305. doi:10.1158/1538-7445.AM2014-2305
RETRACTED: Development of an Experimental Animal Model for Lower Back Pain by Percutaneous Injury‐Induced Lumbar Facet Joint Osteoarthritis
Key PointsThe NF-κB subunits p52 and RelB increase IRF4 promoter activity and expression in PTCL cells. A positive feedback loop involving CD30, NF-κB, and IRF4 drives PTCL cell proliferation and can be blocked by NF-κB inhibitors.
iTagPlot: an accurate computation and interactive drawing tool for tag density plot
Abstract Motivation: Tag density plots are very important to intuitively reveal biological phenomena from capture-based sequencing data by visualizing the normalized read depth in a region. Results: We have developed iTagPlot to compute tag density across functional features in parallel using multicores and a grid engine and to interactively explore it in a graphical user interface. It allows us to stratify features by defining groups based on biological function and measurement, summary statistics and unsupervised clustering. Availability and implementation: http://sourceforge.net/projects/itagplot/. Contact: jechoi@gru.edu and jeochoi@gmail.com Supplementary information: Supplementary data are available at Bioinformatics online.
RETRACTED: Environmental Disruption of Circadian Rhythm Predisposes Mice to Osteoarthritis‐Like Changes in Knee Joint
Proceedings of the International Conference on Bioinformatics Models, Methods and Algorithms | February 2, 2015 | Volume: No volume available | Issue: No issue available | Pages: 163-170
OBJECT Despite a promising outlook, existing intraspinal microstimulation (ISMS) techniques for restoring functional motor control after spinal cord injury are not yet suitable for use outside a controlled laboratory environment. Thus, successful application of ISMS therapy in humans will require the use of versatile chronic neurostimulation systems. The objective of this study was to establish proof of principle for wireless control of ISMS to evoke controlled motor function in a rodent model of complete spinal cord injury. METHODS The lumbar spinal cord in each of 17 fully anesthetized Sprague-Dawley rats was stimulated via ISMS electrodes to evoke hindlimb function. Nine subjects underwent complete surgical transection of the spinal cord at the T-4 level 7 days before stimulation. Targeting for both groups (spinalized and control) was performed under visual inspection via dorsal spinal cord landmarks such as the dorsal root entry zone and the dorsal median fissure. Teflon-insulated stimulating platinum-iridium microwire electrodes (50 μm in diameter, with a 30- to 60-μm exposed tip) were implanted within the ventral gray matter to an approximate depth of 1.8 mm. Electrode implantation was performed using a free-hand delivery technique (n = 12) or a Kopf spinal frame system (n = 5) to compare the efficacy of these 2 commonly used targeting techniques. Stimulation was controlled remotely using a wireless neurostimulation control system. Hindlimb movements evoked by stimulation were tracked via kinematic markers placed on the hips, knees, ankles, and paws. Postmortem fixation and staining of the spinal cord tissue were conducted to determine the final positions of the stimulating electrodes within the spinal cord tissue. RESULTS The results show that wireless ISMS was capable of evoking controlled and sustained activation of ankle, knee, and hip muscles in 90% of the spinalized rats (n = 9) and 100% of the healthy control rats (n = 8). No functional differences between movements evoked by either of the 2 targeting techniques were revealed. However, frame-based targeting required fewer electrode penetrations to evoke target movements. CONCLUSIONS Clinical restoration of functional movement via ISMS remains a distant goal. However, the technology presented herein represents the first step toward restoring functional independence for individuals with chronic spinal cord injury.