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How the cuticles of the roughly 4.5 million species of ecdysozoan animals are constructed is not well understood. Here, we systematically mine gene expression datasets to uncover the spatiotemporal blueprint for how the chitin-based pharyngeal cuticle of the nematode Caenorhabditis elegans is built. We demonstrate that the blueprint correctly predicts expression patterns and functional relevance to cuticle development. We find that as larvae prepare to molt, catabolic enzymes are upregulated and the genes that encode chitin synthase, chitin cross-linkers, and homologs of amyloid regulators subsequently peak in expression. Forty-eight percent of the gene products secreted during the molt are predicted to be intrinsically disordered proteins (IDPs), many of which belong to four distinct families whose transcripts are expressed in overlapping waves. These include the IDPAs, IDPBs, and IDPCs, which are introduced for the first time here. All four families have sequence properties that drive phase separation and we demonstrate phase separation for one exemplar in vitro. This systematic analysis represents the first blueprint for cuticle construction and highlights the massive contribution that phase-separating materials make to the structure.

Long Intergenic Non-Protein Coding RNA 1405 (LINC01405), with known elevated expression in muscle, has been linked to a number of musculo-skeletal conditions. By utilizing the CRISPR/Cas9 gene editing system, we generated a LINC01405 knockout human embryonic stem cell (hESC) line. This line remains human stem cell-like morphology and pluripotency, exhibits a normal karyotype, and can differentiate into cells from all three germ layers. This cell line will be an invaluable model for the research on LINC01405's role in normal development of cardiac and skeletal muscle, and their diseases.