Chemical suppression of a genetic mutation in a zebrafish model of aortic coarctation

Abstract

Conventional drug discovery approaches require a priori selection of an appropriate molecular target, but it is often not obvious which biological pathways must be targeted to reverse a disease phenotype. Phenotype-based screens offer the potential to identify pathways and potential therapies that influence disease processes. The zebrafish mutation gridlock (grl, affecting the gene hey2) disrupts aortic blood flow in a region and physiological manner akin to aortic coarctation in humans. Here we use a whole-organism, phenotype-based, small-molecule screen to discover a class of compounds that suppress the coarctation phenotype and permit survival to adulthood. These compounds function during the specification and migration of angioblasts. They act to upregulate expression of vascular endothelial growth factor (VEGF), and the activation of the VEGF pathway is sufficient to suppress the gridlock phenotype. Thus, organism-based screens allow the discovery of small molecules that ameliorate complex dysmorphic syndromes even without targeting the affected gene directly.

Zebrafish: A model system for the study of eye genetics

“…Second, compounds may be applied to the embryos at any stage of development, thereby revealing the timing of gene action and limiting the pitfalls associated with the loss of function mutations displaying an earlier developmental phenotype that may otherwise obscure later functions of the gene. The ability to screen large numbers of compounds led to a novel application of the chemical genetic screen to identify compounds with the potential to suppress the lethal phenotype of a genetic mutation (Peterson et al, 2004). Two of the 5000 compounds tested rescued the embryonic vascular defect associated with the mutation gridlock (grl affects hey2), and following the early treatment, the rescued mutants remained viable into adulthood.…”

KBP is essential for axonal structure, outgrowth and maintenance in zebrafish, providing insight into the cellular basis of Goldberg-Shprintzen syndrome

“…Further analyses of our zebrafish kbp mutant may provide a basis to pursue and evaluate potential therapies for Goldberg-Shprintzen syndrome and axonal degeneration. The zebrafish is emerging as an ideal system in which to carry out drug discovery screens in vivo (Murphey and Zon, 2006;Peterson et al, 2004;North et al, 2007). Identification of compounds that affect KBP activity may provide mechanistic insight into its function that may not be easily derived from other approaches.…”

Zebrafish: At the Nexus of Functional and Chemical Genomics

“…An assay rnust be applicable (eventuaHy) to a high throughput process, but offer the abiJity to answer potentially cOlnplex questions related to the disease process. It should nOl go unnoticed lhat a high throughput approach lends itsel f to screening thousands of snla]) 1l10)ecules, wh ich has received recent attention with respect to the use of zebrafish elnbryos (Pichler et al., 2003;Goldsrllith, 2004;Love et aJ., 2004;Peterson, 2004;Peterson et al, 2004). The principal outcotne to these studies should be to provide high biological value to the disease being studied, while at the saIne thue achieving a throughput thal serves as a drug discovery platfoTill.…”