Browsing by Author "Ren, Bing"

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    CTCF mediates chromatin looping via N-terminal domain-dependent cohesin retention
    (National Academy of Sciences, 2020-01-28) Pugacheva, Elena M.; Kubo, Naoki; Loukinov, Dmitri; Tajmul, Md; Kang, Sungyun; Kovalchuk, Alexander L.; Strunnikov, Alexander V.; Zentner, Gabriel E.; Ren, Bing; Lobanenkov, Victor V.; Medicine, School of Medicine
    The DNA-binding protein CCCTC-binding factor (CTCF) and the cohesin complex function together to shape chromatin architecture in mammalian cells, but the molecular details of this process remain unclear. Here, we demonstrate that a 79-aa region within the CTCF N terminus is essential for cohesin positioning at CTCF binding sites and chromatin loop formation. However, the N terminus of CTCF fused to artificial zinc fingers was not sufficient to redirect cohesin to non-CTCF binding sites, indicating a lack of an autonomously functioning domain in CTCF responsible for cohesin positioning. BORIS (CTCFL), a germline-specific paralog of CTCF, was unable to anchor cohesin to CTCF DNA binding sites. Furthermore, CTCF-BORIS chimeric constructs provided evidence that, besides the N terminus of CTCF, the first two CTCF zinc fingers, and likely the 3D geometry of CTCF-DNA complexes, are also involved in cohesin retention. Based on this knowledge, we were able to convert BORIS into CTCF with respect to cohesin positioning, thus providing additional molecular details of the ability of CTCF to retain cohesin. Taken together, our data provide insight into the process by which DNA-bound CTCF constrains cohesin movement to shape spatiotemporal genome organization.
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    Dynamic changes in P300 enhancers and enhancer-promoter contacts control mouse cardiomyocyte maturation
    (Elsevier, 2023) Zhou, Pingzhu; VanDusen, Nathan J.; Zhang, Yanchun; Cao, Yangpo; Sethi, Isha; Hu, Rong; Zhang, Shuo; Wang, Guangyu; Ye, Lincai; Mazumdar, Neil; Chen, Jian; Zhang, Xiaoran; Guo, Yuxuan; Li, Bin; Ma, Qing; Lee, Julianna Y.; Gu, Weiliang; Gupta, Weiliang; Yuan, Guo-Cheng; Ren, Bing; Chen, Kaifu; Pu, William T.; Pediatrics, School of Medicine
    Cardiomyocyte differentiation continues throughout murine gestation and into the postnatal period, driven by temporally regulated expression changes in the transcriptome. The mechanisms that regulate these developmental changes remain incompletely defined. Here, we used cardiomyocyte-specific ChIP-seq of the activate enhancer marker P300 to identify 54,920 cardiomyocyte enhancers at seven stages of murine heart development. These data were matched to cardiomyocyte gene expression profiles at the same stages and to Hi-C and H3K27ac HiChIP chromatin conformation data at fetal, neonatal, and adult stages. Regions with dynamic P300 occupancy exhibited developmentally regulated enhancer activity, as measured by massively parallel reporter assays in cardiomyocytes in vivo, and identified key transcription factor-binding motifs. These dynamic enhancers interacted with temporal changes of the 3D genome architecture to specify developmentally regulated cardiomyocyte gene expressions. Our work provides a 3D genome-mediated enhancer activity landscape of murine cardiomyocyte development.
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    Splenic-vasculature involvement is associated with poor prognosis in resected distal pancreatic cancer
    (Oxford University Press, 2020-11-24) Yin, Feng; Saad, Mohammed; Lin, Jingmei; Jackson, Christopher R.; Ren, Bing; Lawson, Cynthia; Karamchandani, Dipti M.; Bernabeu, Belen Quereda; Jiang, Wei; Dhir, Teena; Zheng, Richard; Schultz, Christopher W.; Zhang, Dongwei; Thomas, Courtney L.; Zhang, Xuchen; Lai, Jinping; Schild, Michael; Zhang, Xuefeng; Xie, Hao; Liu, Xiuli; Pathology and Laboratory Medicine, School of Medicine
    Background: Distal pancreatic carcinoma is one of the most lethal cancers largely due to its high incidence of distant metastasis. This study aims to assess the prognostic value of splenic-vasculature involvement in resected distal pancreatic carcinoma. Methods: In this retrospective study, we collected the clinicopathologic information of 454 patients with pancreatic cancer and performed univariate and multivariate analyses to identify factors associated with progression-free survival (PFS) and overall survival (OS), with an emphasis on the prognostic value of splenic-artery and -vein involvement. Results: Univariate analysis revealed that larger tumor size, non-intraductal papillary mucinous neoplasm (non-IPMN)-associated adenocarcinoma, poor differentiation, stage pT3, nodal metastasis, lymphovascular invasion, perineural invasion, and pathologic and radiographic evidence of splenic-vein invasion were significantly associated with shorter PFS and OS (all P < 0.05). Multivariate analysis confirmed non-IPMN-associated adenocarcinoma, stage pT3, stage pN1-2, and post-operative adjuvant chemotherapy as independent risk factors for both PFS and OS, and larger tumor size and radiographic evidence of splenic-artery invasion as predictors of PFS only. Conclusion: Guidelines should be developed for a uniform approach with regard to the examination and reporting of the status of the splenic vasculature when dealing with distal-pancreatic-cancer specimens.
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    Validation of American Joint Committee on Cancer 8th edition of TNM staging in resected distal pancreatic cancer
    (Baishideng, 2020-06-09) Yin, Feng; Saad, Mohammed; Xie, Hao; Lin, Jingmei; Jackson, Christopher R.; Ren, Bing; Lawson, Cynthia; Karamchandani, Dipti M.; Bernabeu, Belen Quereda; Jiang, Wei; Dhir, Teena; Zheng, Richard; Schultz, Christopher W.; Zhang, Dongwei; Thomas, Courtney L.; Zhang, Xuchen; Lai, Jinping; Schild, Michael; Zhang, Xuefeng; Liu, Xiuli; Medicine, School of Medicine
    BACKGROUND In order to improve risk stratification and clinical management of the pancreatic ductal adenocarcinoma (PDAC), the American Joint Committee on Cancer (AJCC) has published its eighth edition staging manual. Some major changes have been introduced in the new staging system for both T and N categories. Given the rarity of resectable disease, distal pancreatic cancer is likely underrepresented in the published clinical studies, and how the impact of the staging system actually reflects on to clinical outcomes remain unclear. AIM To validate the AJCC 8th edition of TNM staging in distal PDAC. METHODS A retrospective cohort study was performed in seven academic medical centers in the United States. Clinicopathological prognostic factors associated with progression-free survival (PFS) and overall survival (OS) were evaluated through univariate and multivariate analyses. RESULTS Overall, 454 patients were enrolled in the study, and were divided into 2 subgroups: Invasive intraductal papillary mucinous neoplasms (IPMN) (115 cases) and non-IPMN associated adenocarcinoma (339 cases). Compared to invasive IPMN, non-IPMN associated adenocarcinomas are more common in relatively younger patients, have larger tumor size, are more likely to have positive lymph nodes, and are associated with a higher tumor (T) stage and nodal (N) stage, lymphovascular invasion, perineural invasion, tumor recurrence, and a worse PFS and OS. The cohort was predominantly categorized as stage 3 per AJCC 7th edition staging manual, and it’s more evenly distributed based on 8th edition staging manual. T and N staging of both 7th and 8th edition sufficiently stratify PFS and OS in the entire cohort, although dividing into N1 and N2 according to the 8th edition does not show additional stratification. For PDAC arising in IPMN, T staging of the 7th edition and N1/N2 staging of the 8th edition appear to further stratify PFS and OS. For PDAC without an IPMN component, T staging from both versions fails to stratify PFS and OS. CONCLUSION The AJCC 8th edition TNM staging system provides even distribution for the T staging, however, it does not provide better risk stratification than previous staging system for distal pancreatic cancer.