eLife assessment
This important work utilizes a model organism, zebrafish, to explore changes to the proteome and the role of KLHL40, a component of the ubiquitin-proteasome system, in the development of skeletal muscle disease. Using mass spectrometry, the authors demonstrate a major and selective role for proteome remodeling in development. They identify a specific role for KLHL40 deletion in regulating the expression of Sar1 - a key component of biosynthetic secretion, where the resulting elevated levels of Sar1 expression potentially lead to collagen secretion defects in the disease state. The findings are incomplete as further experimental characterization of the overall morphological changes and secretion defects, in particular ones derived from the deregulation of Sar1 levels, is required.