Kristin C. Gunsalus et al.

Nature 436, 861-865 (11 August 2005) | doi: 10.1038/nature03876

Full text

Although numerous fundamental aspects of development have been uncovered through the study of individual genes and proteins, system-level models are still missing for most developmental processes. The first two cell divisions of Caenorhabditis elegans embryogenesis constitute an ideal test bed for a system-level approach. Early embryogenesis, including processes such as cell division and establishment of cellular polarity, is readily amenable to large-scale functional analysis. A first step toward a system-level understanding is to provide first-draft models both of the molecular assemblies involved1 and of the functional connections between them. Here we show that such models can be derived from an integrated gene/protein network generated from three different types of functional relationship2: protein interaction3, expression profiling similarity4 and phenotypic profiling similarity5, as estimated from detailed early embryonic RNA interference phenotypes systematically recorded for hundreds of early embryogenesis genes6. The topology of the integrated network suggests that C. elegans early embryogenesis is achieved through coordination of a limited set of molecular machines. We assessed the overall predictive value of such molecular machine models by dynamic localization of ten previously uncharacterized proteins within the living embryo.