Mutations in human SEC63 cause polycystic liver disease (PCLD). Because Sec63 is a component of the endoplasmic reticulum (ER) translocon machinery, it has been proposed that SEC63 mutations cause PCLD by triggering ER stress, activation of which is also linked to myelin disorders. Monk et al. now describe a zebrafish mutant that was isolated in a screen for mutations affecting the development of myelinated axons. The mutant carries sec63st67, a missense mutation in the zebrafish ortholog of Sec63. The researchers report that liver cells and nervous system cells in sec63st67 mutants show a swollen and fragmented ER, and express molecular markers of ER stress. sec63st67 mutants could therefore serve as a model for studying the role of ER stress in PCLD and in myelin disorders. Page 135

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Share Alike License (, which permits unrestricted non-commercial use, distribution and reproduction in any medium provided that the original work is properly cited and all further distributions of the work or adaptation are subject to the same Creative Commons License terms.