Project description:Ribosomes, as a protein synthesis machine, are required for stem cells to maintain self-renewal. Here, we find that DEAD-box RNA helicase DDX10 is necessary for cellular pluripotency acquisition in somatic cell reprogramming, and in mouse embryonic stem cells (mESCs), DDX10 degradation disrupts cellular homeostasis, leads to cell cycle arrest in G1 phase and markedly inhibits cell proliferation. DDX10 is localized in dense fiber component (DFC) and granular component (GC), mainly binds to 45S ribosomal RNA (rRNA) and participates in regulating ribosome biogenesis. Specifically, DDX10 degradation prevents the release of U3 snoRNA from pre-rRNA, and disrupts pre-rRNA processing and maturation of 18S rRNA, leading to impaired ribosomal small subunit production. Together, this study reveals that DDX10 functions as an important regulator of ribosome biogenesis, and is essential for the survival, induction and maintenance of pluripotent stem cells.
Project description:Ribosomes, as a protein synthesis machine, are required for stem cells to maintain self-renewal. Here, we find that DEAD-box RNA helicase DDX10 is necessary for cellular pluripotency acquisition in somatic cell reprogramming, and in mouse embryonic stem cells (mESCs), DDX10 degradation disrupts cellular homeostasis, leads to cell cycle arrest in G1 phase and markedly inhibits cell proliferation. DDX10 is localized in dense fiber component (DFC) and granular component (GC), mainly binds to 45S ribosomal RNA (rRNA) and participates in regulating ribosome biogenesis. Specifically, DDX10 degradation prevents the release of U3 snoRNA from pre-rRNA, and disrupts pre-rRNA processing and maturation of 18S rRNA, leading to impaired ribosomal small subunit production. Together, this study reveals that DDX10 functions as an important regulator of ribosome biogenesis, and is essential for the survival, induction and maintenance of pluripotent stem cells.
Project description:NUP98 rearrangements associated with acute myeloid leukemia and myelodysplastic syndromes generate NUP98-fusion proteins. One such fusion protein, NUP98::DDX10, contains the putative RNA helicase DDX10. The molecular mechanism by which NUP98::DDX10 induces leukemia is not well understood. Here, we show that 24 amino acids within the DDX10 moiety of NUP98::DDX10 are crucial for cell immortalization and leukemogenesis. NOL10, nucleolar protein 10, interacts with the 24 amino acids, and NOL10 is a critical dependency of NUP98::DDX10 leukemia development. Studies in a mouse model of NUP98::DDX10 leukemia showed that loss of Nol10 impaired disease progression and improved survival. We also identified a novel function of NOL10 in that it acts cooperatively with NUP98::DDX10 to regulate serine biosynthesis pathways and stabilize ATF4 mRNA. Collectively, these findings suggest that NOL10 is a critical regulator of NUP98::DDX10 leukemia, and that targeting NOL10 (or the serine synthesis pathway regulated by NOL10) may be an effective therapeutic approach.
Project description:RNA-binding proteins (RBPs) function in all steps of cellular RNA metabolism. Here, we find that Ddx10 gain-of-function promotes but loss-of-function impedes somatic cell reprogramming. Ddx10 loss-of-function results in significantly abnormal expression of innate immune response genes at the late stage of reprogramming. Knockdown of interferon transcription factor Irf1 or its downstream targets, Igtp and Tgtp2, respectively, obviously inhibited reprogramming. This study revealed that Ddx10 regulated reprogramming through modulating innate immune network.
Project description:RNA helicases are important regulators of gene expression that act by remodeling RNA secondary structures and as RNA-protein interactions. Here, we demonstrate that MOV10 has an ATP-dependent 5' to 3' in vitro RNA unwinding activity and determine the RNA-binding sites of MOV10 and its helicase mutants using PAR-CLIP. We find that MOV10 predominantly binds to 3' UTRs upstream of regions predicted to form local secondary structures and provide evidence that MOV10 helicase mutants are impaired in their ability to translocate 5' to 3' on their mRNA targets. MOV10 interacts with UPF1, the key component of the nonsense-mediated mRNA decay pathway. PAR-CLIP of UPF1 reveals that MOV10 and UPF1 bind to RNA in close proximity. Knockdown of MOV10 resulted in increased mRNA half-lives of MOV10-bound as well as UPF1-regulated transcripts, suggesting that MOV10 functions in UPF1-mediated mRNA degradation as an RNA clearance factor to resolve structures and displace proteins from 3' UTRs. Flp-In T-REx HEK293 cells expressing FLAG/HA-tagged MOV10 WT, MOV10 K530A, MOV10 D645N and UPF1 were sequenced. mRNA half-life data under GSE56751.
Project description:RNA helicases are important regulators of gene expression that act by remodeling RNA secondary structures and as RNA-protein interactions. Here, we demonstrate that MOV10 has an ATP-dependent 5' to 3' in vitro RNA unwinding activity and determine the RNA-binding sites of MOV10 and its helicase mutants using PAR-CLIP. We find that MOV10 predominantly binds to 3' UTRs upstream of regions predicted to form local secondary structures and provide evidence that MOV10 helicase mutants are impaired in their ability to translocate 5' to 3' on their mRNA targets. MOV10 interacts with UPF1, the key component of the nonsense-mediated mRNA decay pathway. PAR-CLIP of UPF1 reveals that MOV10 and UPF1 bind to RNA in close proximity. Knockdown of MOV10 resulted in increased mRNA half-lives of MOV10-bound as well as UPF1-regulated transcripts, suggesting that MOV10 functions in UPF1-mediated mRNA degradation as an RNA clearance factor to resolve structures and displace proteins from 3' UTRs.
Project description:SIRT7 is an NAD+-dependent protein deacetylase with important roles in ribosome biogenesis and cell proliferation. Previous studies have established that SIRT7 is associated with RNA polymerase I, interacts with pre-rRNA and promotes rRNA synthesis. Here we show that SIRT7 is also associated with snoRNAs that are involved in pre-rRNA processing and rRNA maturation. Knockdown of SIRT7 impairs U3 snoRNA-dependent early cleavage steps that are necessary for generation of 18S rRNA. Mechanistically, SIRT7 deacetylates U3-55k, a core component of the U3 snoRNP complex, and reversible acetylation of U3-55k modulates the association of U3-55k with U3 snoRNA. Deacetylation by SIRT7 enhances U3-55k binding to U3 snoRNA, which is a prerequisite for pre-rRNA processing. Under stress conditions, SIRT7 is released from nucleoli, leading to hyperacetylation of U3-55k and attenuation of prerRNA processing. The results reveal a multifaceted role of SIRT7 in ribosome biogenesis, regulating both transcription and processing of rRNA. CLIP-seq was performed in Flag-SIRT7-293T cells.