title: Integrating siRNA and protein-protein interaction data to identify an expanded insulin signaling network.
abstract: Insulin resistance is one of the dominant symptoms of type 2 diabetes (T2D). Although the molecular mechanisms leading to this resistance are largely unknown, experimental data support that the insulin signaling pathway is impaired in patients who are insulin resistant. To identify novel components/modulators of the insulin signaling pathway, we designed siRNAs targeting over 300 genes and tested the effects of knocking down these genes in an insulin-dependent, anti-lipolysis assay in 3T3-L1 adipocytes. For 126 genes, significant changes in free fatty acid release were observed. However, due to off-target effects (in addition to other limitations), high-throughput RNAi-based screens in cell-based systems generate significant amounts of noise. Therefore, to obtain a more reliable set of genes from the siRNA hits in our screen, we developed and applied a novel network-based approach that elucidates the mechanisms of action for the true positive siRNA hits. Our analysis results in the identification of a core network underlying the insulin signaling pathway that is more significantly enriched for genes previously associated with insulin resistance than the set of genes annotated in the KEGG database as belonging to the insulin signaling pathway. We experimentally validated one of the predictions, S1pr2, as a novel candidate gene for T2D.
authors.affiliation: Rosetta Inpharmatics, a wholly owned subsidiary of Merck & Co., Inc., Seattle, Washington 98109, USA.
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Tu
authors.forename: Carmen
authors.initials: C
authors.lastname: Argmann
authors.forename: Kenny K
authors.initials: KK
authors.lastname: Wong
authors.forename: Lyndon J
authors.initials: LJ
authors.lastname: Mitnaul
authors.forename: Stephen
authors.initials: S
authors.lastname: Edwards
authors.forename: Iliana C
authors.initials: IC
authors.lastname: Sach
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Eric E
authors.initials: EE
authors.lastname: Schadt
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D030541:Databases, Genetic; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005260:Female; D053263:Gene Regulatory Networks; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007333:Insulin Resistance / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008957:Models, Genetic; D025941:Protein Interaction Mapping / Q000379:methods*; D034741:RNA, Small Interfering / Q000235:genetics*; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D000081025:Sphingosine-1-Phosphate Receptors; D014162:Transfection
chemical_list: D005230:Fatty Acids, Nonesterified; D007004:Hypoglycemic Agents; D007328:Insulin; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D000081025:Sphingosine-1-Phosphate Receptors; C533955:sphingosine-1-phosphate receptor-2, mouse