title: The Warsaw breakage syndrome-related protein DDX11 is required for ribosomal RNA synthesis and embryonic development.
abstract: DDX11 was recently identified as a cause of Warsaw breakage syndrome (WABS). However, the functional mechanism of DDX11 and the contribution of clinically described mutations to the pathogenesis of WABS are elusive. Here, we show that DDX11 is a novel nucleolar protein that preferentially binds to hypomethylated active ribosomal DNA (rDNA) gene loci, where it interacts with upstream binding factor (UBF) and the RNA polymerase I (Pol I). DDX11 knockdown changed the epigenetic state of rDNA loci from euchromatic structures to more heterochromatic structures, reduced the activity of UBF, decreased the recruitment of UBF and RPA194 (a subunit of Pol I) to rDNA promoter, suppressed rRNA transcription and thereby inhibited growth and proliferation of HeLa cells. Importantly, two indentified WABS-derived mutants, R263Q and K897del, and a Fe-S deletion construct demonstrated significantly reduced binding abilities to rDNA promoters and lowered DNA-dependent ATPase activities compared with wild-type DDX11. Knockdown of the zebrafish ortholog of human DDX11 by morpholinos resulted in growth retardation and vertebral and craniofacial malformations in zebrafish, concomitant with the changes in histone epigenetic modifications at rDNA loci, the reduction of Pol I recruitment to the rDNA promoter and a significant decrease in nascent pre-RNA levels. These growth disruptions in zebrafish in response to DDX11 reduction showed similarities to the clinically described developmental abnormalities found in WABS patients for the first time in any vertebrate. Thus, our results indicate that DDX11 functions as a positive regulator of rRNA transcription and provides a novel insight into the pathogenesis of WABS.
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China.
authors.forename: Xinliang
authors.initials: X
authors.lastname: Sun
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China, malan@sz.tsinghua.edu.cn caigp@mail.tsinghua.edu.cn chen.hongbo@sz.tsinghua.edu.cn.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China.
authors.forename: Zaian
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Department of Laboratory Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Pharmacology, Guangdong Medical College, Zhanjiang 524023, Guangdong, China and and.
authors.forename: Hui
authors.initials: H
authors.lastname: Luo
authors.affiliation: Department of Pharmacology, Guangdong Medical College, Zhanjiang 524023, Guangdong, China and and.
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong, China.
authors.forename: Liqiao
authors.initials: L
authors.lastname: Han
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China, malan@sz.tsinghua.edu.cn caigp@mail.tsinghua.edu.cn chen.hongbo@sz.tsinghua.edu.cn.
authors.forename: Guoping
authors.initials: G
authors.lastname: Cai
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China, malan@sz.tsinghua.edu.cn caigp@mail.tsinghua.edu.cn chen.hongbo@sz.tsinghua.edu.cn.
authors.forename: Lan
authors.initials: L
authors.lastname: Ma
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism; D049109:Cell Proliferation; D053487:DEAD-box RNA Helicases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D047108:Embryonic Development / Q000235:genetics*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D035463:Pol1 Transcription Initiation Complex Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021381:Protein Transport; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D034741:RNA, Small Interfering / Q000235:genetics; D014158:Transcription, Genetic; D015027:Zebrafish
chemical_list: D035463:Pol1 Transcription Initiation Complex Proteins; D012335:RNA, Ribosomal; D034741:RNA, Small Interfering; C063844:transcription factor UBF; D004265:DNA Helicases; C101830:DDX11 protein, human; D053487:DEAD-box RNA Helicases