Feedback Control of Gene Expression Variability in the Caenorhabditis elegans Wnt Pathway

• Published in: Cell Vol. 155; no. 4; pp. 869 - 880
• Main Authors: Ji, Ni, Middelkoop, Teije C., Mentink, Remco A., Betist, Marco C., Tonegawa, Satto, Mooijman, Dylan, Korswagen, Hendrik C., van Oudenaarden, Alexander
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.11.2013
• Subjects: Animals; Caenorhabditis elegans; Caenorhabditis elegans - cytology; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - genetics; Cell Movement; Embryo, Nonmammalian - cytology; Embryo, Nonmammalian - metabolism; Feedback, Physiological; Frizzled Receptors - genetics; Frizzled Receptors - metabolism; gene expression; Gene Regulatory Networks; Genetic Variation; Glycoproteins - genetics; Homeodomain Proteins - genetics; homeotic genes; mutants; phenotypic variation; population; Transcription Factors - genetics; Wnt Signaling Pathway
• ISSN: 0092-8674; 1097-4172; 1097-4172
• DOI: 10.1016/j.cell.2013.09.060

Variability in gene expression contributes to phenotypic heterogeneity even in isogenic populations. Here, we used the stereotyped, Wnt signaling-dependent development of the Caenorhabditis elegans Q neuroblast to probe endogenous mechanisms that control gene expression variability. We found that the key Hox gene that orients Q neuroblast migration exhibits increased gene expression variability in mutants in which Wnt pathway activity has been perturbed. Distinct features of the gene expression distributions prompted us on a systematic search for regulatory interactions, revealing a network of interlocked positive and negative feedback loops. Interestingly, positive feedback appeared to cooperate with negative feedback to reduce variability while keeping the Hox gene expression at elevated levels. A minimal model correctly predicts the increased gene expression variability across mutants. Our results highlight the influence of gene network architecture on expression variability and implicate feedback regulation as an effective mechanism to ensure developmental robustness. [Display omitted] [Display omitted] •Single-cell quantification of Wnt-activated Hox gene expression•Wnt signaling mutants exhibit increased variability in Hox gene expression•Multiple interlocked positive and negative feedback exists within the Wnt pathway•Network model explains gene expression variability in the mutants An interlocked positive and negative feedback network embedded in the Wnt signaling pathway ensures robust neuroblast cell migration by dampening gene expression variability.