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Wang J.-W.,CAS Shanghai Institutes for Biological Sciences
Journal of Experimental Botany | Year: 2014

Precise flowering time is critical to reproductive success. In response to diverse exogenous and endogenous cues including age, hormones, photoperiod, and temperature, the floral transition is controlled by a complex regulatory network, which involves extensive crosstalks, feedback, or feedforward loops between the components within flowering time pathways. The newly identified age pathway, which is controlled by microRNA156 (miR156) and its target SQUAMOSA PROMOTER BINDING-LIKE (SPL) transcription factors, ensures plants flower under non-inductive conditions. In this review, I summarize the recent advance in understanding of the age pathway, focusing on the regulatory basis of the developmental decline in miR156 level by age and the molecular mechanism by which the age pathway is integrated into other flowering time pathways. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Zhang S.,CAS Shanghai Institutes for Biological Sciences
Cell Research | Year: 2014

Wor1 (white-opaque switching regulator 1) is a master regulator of the white-opaque switching in Candida albicans, an opportunistic human fungal pathogen, and is associated with its pathogenicity and commensality. Wor1 contains a conserved DNA-binding region at the N-terminus, consisting of two conserved segments (WOPRa and WOPRb) connected by a non-conserved linker that can bind to specific DNA sequences of the promoter regions and then regulates the transcription. Here, we report the crystal structure of the C. albicans Wor1 WOPR segments in complex with a double-stranded DNA corresponding to one promoter region of WOR1. The sequentially separated WOPRa and WOPRb are structurally interwound together to form a compact globular domain that we term the WOPR domain. The WOPR domain represents a new conserved fungal-specific DNA-binding domain which uses primarily a conserved loop to recognize and interact specifically with a conserved 6-bp motif of the DNA in both minor and major grooves. The protein-DNA interactions are essential for WOR1 transcriptional regulation and white-to-opaque switching. The structural and biological data together reveal the molecular basis for the recognition and binding specificity of the WOPR domain with its specific DNA sequences and the function of Wor1 in the activation of transcription.Cell Research advance online publication 5 August 2014; doi:10.1038/cr.2014.102.

Neural progenitor cells (NPCs) derived from human embryonic stem cells (hESCs) have great potential in cell therapy, drug screening and toxicity testing of neural degenerative diseases. However, the molecular regulation of their proliferation and apoptosis, which needs to be revealed before clinical application, is largely unknown. MicroRNA miR-195 is known to be expressed in the brain and is involved in a variety of proapoptosis or antiapoptosis processes in cancer cells. Here, we defined the proapoptotic role of miR-195 in NPCs derived from two independent hESC lines (human embryonic stem cell-derived neural progenitor cells, hESC-NPCs). Overexpression of miR-195 in hESC-NPCs induced extensive apoptotic cell death. Consistently, global transcriptional microarray analyses indicated that miR-195 primarily regulated genes associated with apoptosis in hESC-NPCs. Mechanistically, a small GTP-binding protein ADP-ribosylation factor-like protein 2 (ARL2) was identified as a direct target of miR-195. Silencing ARL2 in hESC-NPCs provoked an apoptotic phenotype resembling that of miR-195 overexpression, revealing for the first time an essential role of ARL2 for the survival of human NPCs. Moreover, forced expression of ALR2 could abolish the cell number reduction caused by miR-195 overexpression. Interestingly, we found that paraquat, a neurotoxin, not only induced apoptosis but also increased miR-195 and reduced ARL2 expression in hESC-NPCs, indicating the possible involvement of miR-195 and ARL2 in neurotoxin-induced NPC apoptosis. Notably, inhibition of miR-195 family members could block neurotoxin-induced NPC apoptosis. Collectively, miR-195 regulates cell apoptosis in a context-dependent manner through directly targeting ARL2. The finding of the critical role of ARL2 for the survival of human NPCs and association of miR-195 and ARL2 with neurotoxin-induced apoptosis have important implications for understanding molecular mechanisms that control NPC survival and would facilitate our manipulation of the neurological pathogenesis.

Wang S.,CAS Shanghai Institutes for Biological Sciences | Jacobs-Lorena M.,Malaria Research Institute
Trends in Biotechnology | Year: 2013

Malaria remains one of the most devastating diseases worldwide, causing over 1 million deaths every year. The most vulnerable stages of Plasmodium development in the vector mosquito occur in the midgut lumen, making the midgut a prime target for intervention. Mosquito transgenesis and paratransgenesis are two novel strategies that aim at rendering the vector incapable of sustaining Plasmodium development. Mosquito transgenesis involves direct genetic engineering of the mosquito itself for delivery of anti-. Plasmodium effector molecules. Conversely, paratransgenesis involves the genetic modification of mosquito symbionts for expression of anti-pathogen effector molecules. Here we consider both genetic manipulation strategies for rendering mosquitoes refractory to Plasmodium infection, and discuss challenges for the translation of laboratory findings to field applications. © 2013 Elsevier Ltd.

Ge X.,CAS Shanghai Institutes for Biological Sciences
International journal of biological sciences | Year: 2013

The current identification of microRNAs (miRNAs) in insects is largely dependent on genome sequences. However, the lack of available genome sequences inhibits the identification of miRNAs in various insect species. In this study, we used a miRNA database of the silkworm Bombyx mori as a reference to identify miRNAs in Helicoverpa armigera and Spodoptera litura using deep sequencing and homology analysis. Because all three species belong to the Lepidoptera, the experiment produced reliable results. Our study identified 97 and 91 conserved miRNAs in H. armigera and S. litura, respectively. Using the genome of B. mori and BAC sequences of H. armigera as references, 1 novel miRNA and 8 novel miRNA candidates were identified in H. armigera, and 4 novel miRNA candidates were identified in S. litura. An evolutionary analysis revealed that most of the identified miRNAs were insect-specific, and more than 20 miRNAs were Lepidoptera-specific. The investigation of the expression patterns of miR-2a, miR-34, miR-2796-3p and miR-11 revealed their potential roles in insect development. miRNA target prediction revealed that conserved miRNA target sites exist in various genes in the 3 species. Conserved miRNA target sites for the Hsp90 gene among the 3 species were validated in the mammalian 293T cell line using a dual-luciferase reporter assay. Our study provides a new approach with which to identify miRNAs in insects lacking genome information and contributes to the functional analysis of insect miRNAs.

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