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c-Cbl-Mediated Neddylation Antagonizes Ubiquitination and Degradation of the TGF-β Type II Receptor
Zuo, W.,Huang, F.,Chiang, Y.,Li, M.,Du, J.,Ding, Y.,Zhang, T.,Lee, H.,Jeong, L.,Chen, Y.,Deng, H.,Feng, X.H.,Luo, S.,Gao, C.,Chen, Y.G. Cell Press 2013 Molecular cell Vol.49 No.3
Transforming growth factor β (TGF-β) is a potent antiproliferative factor in multiple types of cells. Deregulation of TGF-β signaling is associated with the development of many cancers, including leukemia, though the molecular mechanisms are largely unclear. Here, we show that Casitas B-lineage lymphoma (c-Cbl), a known proto-oncogene encoding an ubiquitin E3 ligase, promotes TGF-β signaling by neddylating and stabilizing the type II receptor (TβRII). Knockout of c-Cbl decreases the TβRII protein level and desensitizes hematopoietic stem or progenitor cells to TGF-β stimulation, while c-Cbl overexpression stabilizes TβRII and sensitizes leukemia cells to TGF-β. c-Cbl conjugates neural precursor cell-expressed, developmentally downregulated 8 (NEDD8), a ubiquitin-like protein, to TβRII at Lys556 and Lys567. Neddylation of TβRII promotes its endocytosis to EEA1-positive early endosomes while preventing its endocytosis to caveolin-positive compartments, therefore inhibiting TβRII ubiquitination and degradation. We have also identified a neddylation-activity-defective c-Cbl mutation from leukemia patients, implying a link between aberrant TβRII neddylation and leukemia development.
RNA Interference-Mediated Simultaneous Silencing of Four Genes Using Cross-Shaped RNA
이태연,이동기,장찬일,이두영,홍선우,신찬석,Chiang J. Li,김소연,Dirk Haussecker 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.4
The structural flexibility of RNA interference (RNAi)-trig-gering nucleic acids suggests that the design of uncon-ventional RNAi trigger structures with novel features is possible. Here, we report a cross-shaped RNA duplex structure, termed quadruple interfering RNA (qiRNA), with multiple target gene silencing activity. qiRNA trig-gers the simultaneous down-regulation of four cellular target genes via an RNAi mechanism. In addition, qiRNA shows enhanced intracellular delivery and target gene silencing over conventional siRNA when complexed with jetPEI, a linear polyethyleneimine (PEI). We also show that the long antisense strand of qiRNA is incorporated intact into an RNA-induced silencing complex (RISC). This novel RNA scaffold further expands the repertoire of RNAi-triggering molecular structures and could be used in the development of therapeutics for various diseases including viral infections and cancer.
Chang, Chan Il,Yoo, Jae Wook,Hong, Sun Woo,Lee, Shi Eun,Kang, Hye Suk,Sun, Xiangao,Rogoff, Harry A,Ban, Changill,Kim, Soyoun,Li, Chiang J,Lee, Dong-ki Elsevier 2009 Molecular therapy Vol.17 No.4
<P>Small interfering RNAs (siRNAs) are short, double-stranded RNAs that mediate efficient gene silencing in a sequence-specific manner by utilizing the endogenous RNA interference (RNAi) pathway. The current standard synthetic siRNA structure harbors a 19-base-pair duplex region with 3' overhangs of 2 nucleotides (the so-called 19+2 form). However, the synthetic 19+2 siRNA structure exhibits several sequence-independent, nonspecific effects, which has posed challenges to the development of RNAi therapeutics and specific silencing of genes in research. In this study, we report on the identification of truncated siRNA backbone structures with duplex regions shorter than 19 bp (referred to as asymmetric shorter-duplex siRNAs or asiRNAs) that can efficiently trigger gene silencing in human cell lines. Importantly, this asiRNA structure significantly reduces nonspecific effects triggered by conventional 19+2 siRNA scaffold, such as sense-strand-mediated off-target gene silencing and saturation of the cellular RNAi machinery. Our results suggest that this asiRNA structure is an important alternative to conventional siRNAs for both functional genomics studies and therapeutic applications.</P>