Supplementary material from "Zebrafish reveal new roles for Fam83f in hatching and the DNA damage-mediated autophagic response"

The FAM83 (Family with sequence similarity 83) family is highly conserved in vertebrates, but little is known about these proteins beyond their association with oncogenesis. FAM83F is the only membrane-targeted FAM83 protein, and when over-expressed, FAM83F activates Wnt signalling and binds to and stabilizes p53; two pathways often dysregulated in disease. Insights into gene function can be gained by studying the roles they play during development, and here we generate fam83f knock-out (KO) zebrafish, which we use to study the role of Fam83f in vivo. We show fam83f is strongly expressed in the hatching gland, and fam83f KO embryos hatch earlier than wild-type (WT). We demonstrate that fam83f KO embryos are more sensitive to ionizing radiation than WT — an unexpected finding, considering the previously-reported ability of FAM83F to stabilize p53. Transcriptomic analysis shows that loss of fam83f leads to downregulation of phosphatidylinositol-3-phosphate binding proteins and impairment of autophagy, a component of the DNA damage response. Finally, we show that Fam83f is targeted to the lysosome, and this localization is dependent upon a C’ signal sequence. Our data suggest Fam83f plays an important role in autophagic/lysosomal processes, resulting in dysregulated hatching and increased sensitivity to genotoxic stress in fam83f KO embryos.