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Zhang L, Xu W, Gao X, Li W, Qi S, Guo D, Ajayi OE, Ding SW, Wu Q. lncRNA Sensing of a Viral Suppressor of RNAi Activates Non-canonical Innate Immune Signaling in Drosophila. Cell Host Microbe 2020; 27:115-128.e8. [PMID: 31917956 DOI: 10.1016/j.chom.2019.12.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/10/2019] [Accepted: 11/18/2019] [Indexed: 12/30/2022]
Abstract
Antiviral immunity in insects is mediated by the RNA interference (RNAi) pathway. Viruses evade antiviral RNAi by expressing virulence factors known as viral suppressors of RNAi (VSR). Here, we report the identification of VINR, a Drosophila VSR-interacting long non-coding (lnc) RNA that activates non-canonical innate immune signaling upon detection of the dsRNA-binding VSR of Drosophila C virus (DCV). VINR is required for the induction of antimicrobial peptide (AMP) genes but dispensable for antiviral RNAi. VINR functions by preventing the ubiquitin proteasome-dependent degradation of Cactin, a coiled-coil and arginine-serine-rich domain-containing protein that regulates a non-cannonical antimicrobial pathway for AMP induction. CRISPR-Cas9 knockout of VINR in Drosophila cells enhances DCV replication independently of antiviral RNAi, and VINR-knockout adult flies exhibit enhanced disease susceptibility to DCV and bacteria. Our findings reveal a counter counter-defense strategy activated by a lncRNA in response to the viral suppression of the primary antiviral RNAi immunity.
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Affiliation(s)
- Liqin Zhang
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Wen Xu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Xinlei Gao
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Wenjie Li
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Shuishui Qi
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Dongyang Guo
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Olugbenga Emmanuel Ajayi
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Shou-Wei Ding
- Department of Microbiology and Plant Pathology, Institute for Integrative Genome Biology, University of California, Riverside CA, USA
| | - Qingfa Wu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
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Gobert V, Haenlin M, Waltzer L. Myeloid leukemia factor: a return ticket from human leukemia to fly hematopoiesis. Transcription 2012; 3:250-4. [PMID: 22885977 DOI: 10.4161/trns.21490] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Even though deregulation of human MLF1, the founding member of the Myeloid Leukemia Factor family, has been associated with acute myeloid leukemia, the function and mode of action of this family of genes have remained rather mysterious. Yet, recent findings in Drosophila shed new light on their biological activity and suggest that they play an important role in hematopoiesis and leukemia, notably by regulating the stability of RUNX transcription factors, another family of conserved proteins with prominent roles in normal and malignant blood cell development.
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Affiliation(s)
- Vanessa Gobert
- Université de Toulouse, UPS, CBD-Centre de Biologie du Développement, Bat4R3, Toulouse, France
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Myeloid leukemia factor is a conserved regulator of RUNX transcription factor activity involved in hematopoiesis. Proc Natl Acad Sci U S A 2012; 109:4986-91. [PMID: 22411814 DOI: 10.1073/pnas.1117317109] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Defining the function of the genes that, like RUNX1, are deregulated in blood cell malignancies represents an important challenge. Myeloid leukemia factors (MLFs) constitute a poorly characterized family of conserved proteins whose founding member, MLF1, has been associated with acute myeloid leukemia in humans. To gain insight into the functions of this family, we investigated the role of the Drosophila MLF homolog during blood cell development. Here we report that mlf controls the homeostasis of the Drosophila hematopoietic system. Notably, mlf participates in a positive feedback loop to fine tune the activity of the RUNX transcription factor Lozenge (LZ) during development of the crystal cells, one of the two main blood cell lineages in Drosophila. At the molecular level, our data in cell cultures and in vivo strongly suggest that MLF controls the number of crystal cells by protecting LZ from degradation. Remarkably, it appears that the human MLF1 protein can substitute for MLF in the crystal cell lineage. In addition, MLF stabilizes the human oncogenic fusion protein RUNX1-ETO and is required for RUNX1-ETO-induced blood cell disorders in a Drosophila model of leukemia. Finally, using the human leukemic blood cell line Kasumi-1, we show that MLF1 depletion impairs RUNX1-ETO accumulation and reduces RUNX1-ETO-dependent proliferation. Thus, we propose that the regulation of RUNX protein levels is a conserved feature of MLF family members that could be critical for normal and pathological blood cell development.
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