genomewide characterization of host-pathogen interactions by ...
genomewide characterization of host-pathogen interactions by ...
genomewide characterization of host-pathogen interactions by ...
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Maren Depke<br />
Material and Methods<br />
Gene Expression Pattern <strong>of</strong> Bone-Marrow Derived Macrophages after Interferon-gamma Treatment<br />
<strong>of</strong> proteins was imported into the Rosetta Resolver s<strong>of</strong>tware using the EntrezGene IDs and<br />
compared with genes on the Affymetrix array based on the annotation <strong>of</strong> the Rosetta Resolver<br />
s<strong>of</strong>tware.<br />
Global functional analysis <strong>of</strong> transcriptomic [Maren Depke] and proteomic [Dinh Hoang Dang<br />
Khoa] results using Ingenuity Pathway Analysis (IPA)<br />
The lists <strong>of</strong> differentially expressed genes with an absolute fold change <strong>of</strong> at least 1.5 were<br />
directly uploaded from Rosetta Resolver System to the Ingenuity Pathway Analysis tool Version<br />
7.5 and 8.0 (IPA, Ingenuity Systems, www.ingenuity.com). IPA assigned the EntrezGene IDs to the<br />
corresponding records <strong>of</strong> the so called Ingenuity Pathway Knowledge Base (IPKB), combined<br />
related genes to networks and conducted a statistical analysis for over-represented functions and<br />
canonical pathways in the imported lists <strong>of</strong> differentially expressed items in relation to the<br />
sequences available on the GeneChip Mouse Gene 1.0 ST Array as reference set. Generally,<br />
analysis in IPA was not restricted to species, type <strong>of</strong> relationship, type <strong>of</strong> molecule or the like.<br />
Only for building user-defined pathways, a restriction to cell type “macrophages” or “RAW cells”<br />
was used.<br />
Correspondingly, protein IPI identifiers, p-values, and fold change <strong>of</strong> regulated proteins were<br />
uploaded to IPA and also analyzed <strong>by</strong> the network, function and canonical pathway tools. In this<br />
case, the whole list <strong>of</strong> identified proteins was uploaded and afterwards restricted to a minimal<br />
absolute fold change <strong>of</strong> 1.5 and a p-value <strong>of</strong> at least 0.01. This approach allowed using all<br />
identified proteins as reference set.<br />
In case <strong>of</strong> interest, automatically generated networks from separate analyses were merged<br />
using the automatic merge-tool from IPA. User-defined networks (called pathways) centered<br />
around the starting node IFN-γ were created using the grow-tool <strong>of</strong> IPA‘s pathway function. The<br />
addition <strong>of</strong> further nodes according to information stored in the so-called Ingenuity Pathway<br />
Knowledge Base (IPKB) was restricted to a list <strong>of</strong> genes/proteins that are differentially expressed<br />
in at least 1 <strong>of</strong> 4 comparisons 1) IFN-γ effects in BALB/c BMM, 2) IFN-γ effects in C57BL/6 BMM,<br />
3) strain difference at non-treated control level and 4) strain difference after IFN-γ activation.<br />
Networks were built either without further restrictions or with additional restriction to<br />
macrophage/RAW cells (i.e. only genes/proteins in the IPKB described to be linked to IFN-γ in<br />
macrophages or RAW cells were allowed to enter the new network). Lists <strong>of</strong> genes included in<br />
the IFN-γ centered networks were compared to identify common and unique genes between the<br />
networks without and with restriction to macrophage/RAW cells and finally exported via<br />
spreadsheet.<br />
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