CRISPR/Cas9-Mediated Knockout of Rb1 in Xenopus tropicalis

At this time, no molecular targeted therapies exist for treatment of retinoblastoma. This can be, in part, attributed to the lack of animal models that allow for both rapid identification of novel therapeutic targets and hypothesis driven drug testing. Within this scope, we have recently reported the first genuine genetic nonmammalian retinoblastoma cancer model within the aquatic model organism Xenopus tropicalis (Naert et al., Sci Rep 6: 35263, 2016). Here we describe the methods to generate rb1 mosaic mutant Xenopus tropicalis by employing the CRISPR/Cas9 technology. In depth, we discuss short guide RNA (sgRNA) design parameters, generation, quality control, quantification, and delivery followed by several methods for assessing genome editing efficiencies. As such the reader should be capable, by minor changes to the methods described here, to (co-) target rb1 or any one or multiple gene(s) within the Xenopus tropicalis genome by multiplex CRISPR/Cas9 methodology.