scholarly journals Lysine 27 of replication-independent histone H3.3 is required for Polycomb target gene silencing but not for gene activation

PLoS Genetics ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. e1007932 ◽  
Author(s):  
Mary Leatham-Jensen ◽  
Christopher M. Uyehara ◽  
Brian D. Strahl ◽  
A. Gregory Matera ◽  
Robert J. Duronio ◽  
...  
Botany ◽  
2013 ◽  
Vol 91 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Julian C. Verdonk ◽  
Michael L. Sullivan

Gene silencing is a powerful technique that allows the study of the function of specific genes by selectively reducing their transcription. Several different approaches can be used, however they all have in common the artificial generation of single stranded small ribonucleic acids (RNAs) that are utilized by the endogenous gene silencing machinery of the organism. Artificial microRNAs (amiRNA) can be used to very specifically target genes for silencing because only a short sequence of 21 nucleotides of the gene of interest is used. Gene silencing via amiRNA has been developed for Arabidopsis thaliana (L.) Heynh. and rice using endogenous microRNA (miRNA) precursors and has been shown to also work effectively in other dicot species using the arabidopsis miRNA precursor. Here, we demonstrate that the arabidopsis miR319 precursor can be used to silence genes in the important forage crop species alfalfa (Medicago sativa L.) by silencing the expression of a transgenic beta-glucuronidase (GUSPlus) target gene.


Blood ◽  
2019 ◽  
Vol 133 (8) ◽  
pp. 830-839 ◽  
Author(s):  
Viola Close ◽  
William Close ◽  
Sabrina Julia Kugler ◽  
Michaela Reichenzeller ◽  
Deyan Yordanov Yosifov ◽  
...  

Abstract NOTCH1 is mutated in 10% of chronic lymphocytic leukemia (CLL) patients and is associated with poor outcome. However, NOTCH1 activation is identified in approximately one-half of CLL cases even in the absence of NOTCH1 mutations. Hence, there appear to be additional factors responsible for the impairment of NOTCH1 degradation. E3-ubiquitin ligase F-box and WD40 repeat domain containing-7 (FBXW7), a negative regulator of NOTCH1, is mutated in 2% to 6% of CLL patients. The functional consequences of these mutations in CLL are unknown. We found heterozygous FBXW7 mutations in 36 of 905 (4%) untreated CLL patients. The majority were missense mutations (78%) that mostly affected the WD40 substrate binding domain; 10% of mutations occurred in the first exon of the α-isoform. To identify target proteins of FBXW7 in CLL, we truncated the WD40 domain in CLL cell line HG-3 via clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9). Homozygous truncation of FBXW7 resulted in an increase of activated NOTCH1 intracellular domain (NICD) and c-MYC protein levels as well as elevated hypoxia-inducible factor 1-α activity. In silico modeling predicted that novel mutations G423V and W425C in the FBXW7-WD40 domain change the binding of protein substrates. This differential binding was confirmed via coimmunoprecipitation of overexpressed FBXW7 and NOTCH1. In primary CLL cells harboring FBXW7 mutations, activated NICD levels were increased and remained stable upon translation inhibition. FBXW7 mutations coincided with an increase in NOTCH1 target gene expression and explain a proportion of patients characterized by dysregulated NOTCH1 signaling.


2007 ◽  
Vol 6 (8) ◽  
pp. 1299-1309 ◽  
Author(s):  
T. Krajaejun ◽  
G. M. Gauthier ◽  
C. A. Rappleye ◽  
T. D. Sullivan ◽  
B. S. Klein

ABSTRACT A high-throughput strategy for testing gene function would accelerate progress in our understanding of disease pathogenesis for the dimorphic fungus Blastomyces dermatitidis, whose genome is being completed. We developed a green fluorescent protein (GFP) sentinel system of gene silencing to rapidly study genes of unknown function. Using Gateway technology to efficiently generate RNA interference plasmids, we cloned a target gene, “X,” next to GFP to create one hairpin to knock down the expression of both genes so that diminished GFP reports target gene expression. To test this approach in B. dermatitidis, we first used LACZ and the virulence gene BAD1 as targets. The level of GFP reliably reported interference of their expression, leading to rapid detection of gene-silenced transformants. We next investigated a previously unstudied gene encoding septin and explored its possible role in morphogenesis and sporulation. A CDC11 septin homolog in B. dermatitidis localized to the neck of budding yeast cells. CDC11-silenced transformants identified with the sentinel system grew slowly as flat or rough colonies on agar. Microscopically, they formed ballooned, distorted yeast cells that failed to bud, and they sporulated poorly as mold. Hence, this GFP sentinel system enables rapid detection of gene silencing and has revealed a pronounced role for septin in morphogenesis, budding, and sporulation of B. dermatitidis.


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