dictyNews

Electronic Edition

Volume 45, number 32

December 19, 2019



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Abstracts

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Investigation of the host transcriptional response to intracellular bacterial 

infection using Dictyostelium discoideum as a host model.



Jonas Kjellin, Maria Pränting, Frauke Bach, Roshan Vaid, Bart Edelbroek, 

Zhiru Li, Marc P. Hoeppner, Manfred Grabherr, Ralph R. Isberg, Monica 

Hagedorn & Fredrik Söderbom.  





BMC Genomics 20, 961 (2019) doi:10.1186/s12864-019-6269-x



Background

During infection by intracellular pathogens, a highly complex interplay 

occurs between the infected cell trying to degrade the invader and the 

pathogen which actively manipulates the host cell to enable survival and 

proliferation. Many intracellular pathogens pose important threats to human 

health and major efforts have been undertaken to better understand the 

host-pathogen interactions that eventually determine the outcome of the 

infection. Over the last decades, the unicellular eukaryote Dictyostelium 

discoideum has become an established infection model, serving as a 

surrogate macrophage that can be infected with a wide range of 

intracellular pathogens. In this study, we use high-throughput RNA-

sequencing to analyze the transcriptional response of D. discoideum 

when infected with Mycobacterium marinum and Legionella pneumophila. 

The results were compared to available data from human macrophages.



Results

The majority of the transcriptional regulation triggered by the two 

pathogens was found to be unique for each bacterial challenge. Hallmark 

transcriptional signatures were identified for each infection, e.g. induction 

of endosomal sorting complexes required for transport (ESCRT) and 

autophagy genes in response to M. marinum and inhibition of genes 

associated with the translation machinery and energy metabolism in 

response to L. pneumophila. However, a common response to the 

pathogenic bacteria was also identified, which was not induced by non-

pathogenic food bacteria. Finally, comparison with available data sets of 

regulation in human monocyte derived macrophages shows that the 

elicited response in D. discoideum is in many aspects similar to what has 

been observed in human immune cells in response to Mycobacterium 

tuberculosis and L. pneumophila.



Conclusions

Our study presents high-throughput characterization of D. discoideum 

transcriptional response to intracellular pathogens using RNA-seq. We 

demonstrate that the transcriptional response is in essence distinct to 

each pathogen and that in many cases, the corresponding regulation is 

recapitulated in human macrophages after infection by mycobacteria 

and L. pneumophila. This indicates that host-pathogen interactions are 

evolutionary conserved, derived from the early interactions between 

free-living phagocytic cells and bacteria. Taken together, our results 

strengthen the use of D. discoideum as a general infection model.





submitted by:  Jonas Kjellin [[log in to unmask]]

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An improved shotgun antisense method for mutagenesis and gene 

identification



Yu Tang and Richard H. Gomer



Department of Biology, Texas A&M University





BioTechniques, accepted



Shotgun expression of antisense cDNAs, where each transformed cell 

expresses a different antisense cDNA, has been used for mutagenesis and 

gene identification in Dictyostelium discoideum. However, the method has 

two limitations. First, there were too few clones in the shotgun antisense 

cDNA library to have an antisense cDNA for every gene in the genome. 

Second, the unequal transcription level of genes caused there to be many 

antisense cDNAs in the library for some genes, but relatively few antisense 

cDNAs for other genes. Here we report an improved method for generating 

a larger antisense cDNA library with a reduced percentage of cDNA clones 

from highly prevalent mRNAs, and demonstrate its utility by screening for 

signal transduction pathway components in Dictyostelium discoideum.





Submitted by: Yu Tang  [[log in to unmask]]

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[End dictyNews, volume 45, number 32]