Abstract 2975: Rad21, as a high order chromatin architecture molecule, regulates global gene transcription.

Abstract

Abstract Rad21 is a subunit of cohesin complex, which is well known to be involved in sister chromatid cohesion at mitotic phase. In recent studies, Rad21 has been also known to be associated with long-range chromosome interaction to dynamically regulate gene transcription. However, Very little is known about Rad21-mediated high order chromatin structure and global changes in gene transcription in human cancer. In this study, we silenced Rad21 gene using Lenti-virus knockdown system and performed transcriptome analysis to verify the changes in gene transcription by knockdown of Rad21. Among genes showing significant transcription changes by the reduction of Rad21, we chose several target genes decreasing its transcription and checked the transcriptional change with passaging over a 60 day period. Interestingly, the change in transcription level of some genes appeared by the earliest passage time point, whereas those of other genes arose during the course of long-term passage. Consistent with gene transcription changes, results from a ChIP assay demonstrated that Rad21-knockdown cells showed low level of Rad21 occupancy and active histone marks (H3K4me3 and Pol2) on the target genes, indicating that dynamic histone modifications also contribute to regulation of the target genes. To figure out whether the reduction of Rad21 binding directly affects the chromatin loops, we applied Chromosome Conformation Capture (3C) -qPCR in Rad21-knockdown cells. The results demonstrated that the decreased Rad21 expression cause overal reduction of locus interaction on the target genes, indicating that Rad21 binding was directly required for long-range interactions at the target gene regions and gene transcription regulation. Taken together, the results of our study demonstrated that long-range chromosome interaction mediated by Rad21 can dynamically regulate global gene transcription in human cancer cells, indicating that it may be important for cancer development. Citation Format: Jiyeon Yun, Sang-Hyun Song, Jee-Youn Kang, Hwang-Phill Kim, Sae-Won Han, Do-Youn Oh, Seock-Ah Im, Yung-Jue Bang, Tae-You Kim. Rad21, as a high order chromatin architecture molecule, regulates global gene transcription. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2975. doi:10.1158/1538-7445.AM2013-2975 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.