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Mutations in transcription factor p63 are associated with developmental disorders that manifest defects in stratified epithelia including the epidermis. The underlying cellular and molecular mechanism is however not yet understood. We established an epidermal commitment model using human induced pluripotent stem cells (iPSCs) and characterized differentiation defects of iPSCs derived from ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome patients carrying p63 mutations. Transcriptome analyses revealed distinct step-wise cell fate transitions during epidermal commitment; from multipotent simple epithelium to basal stratified epithelia, and ultimately to the mature epidermal fate. Differentiation defects of EEC iPSCs caused by mutant p63 occurred during the specification switch from the simple epithelium to the basal stratified epithelial fate. Single-cell transcriptome and pseudotime analyses identified signatures of embryonic epithelial-mesenchymal transition (EMT) associated with the deviated commitment route of EEC iPSCs. Repressing mesodermal activation reversed the EMT and enhanced epidermal commitment. Our findings demonstrate that p63 is required for specification of stratified epithelia, probably by repressing embryonic EMT during epidermal commitment. This study provides insights into disease mechanisms underlying stratified epithelial defects caused by p63 mutations and suggests potential therapeutic strategies for the disease.Significance statementMutations in p63 cause several developmental disorders with defects of epithelial related organs and tissues including the epidermis. Our study is to dissect the unknown cellular and molecular pathomechanism. We utilized human induced pluripotent stem cells (iPSCs) derived from ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome patients carrying p63 mutations and studied transcriptome changes during differentiation of these cells to epidermal cells. Our analyses showed that the specification of the proper epithelial cell fate was affected by p63 EEC mutations, with an abnormal embryonic epithelial-mesenchymal transition (EMT). Repressing mesodermal activation reversed the EMT and enhanced epidermal commitment. This study provides insights into disease mechanisms associated with p63 mutations and suggests potential therapeutic strategies.

This paper describes a new genus and a new species of Euptychiina from open grassland habitats (campos de cima da serra) in southern Brazil. The systematic position of this new taxon is discussed based on morphological and molecular data, and it is considered sister to Taydebis Freitas. Since the campos vegetation is considered endangered due to anthropogenic activities, this butterfly species deserves attention and should be included in future conservation plans for this biome.

Summary Mutations in KCNH2 can lead to long QT syndrome type 2. Variable disease manifestation observed with this channelopathy is associated with the location and type of mutation within the protein, complicating efforts to predict patient risk. Here, we demonstrated phenotypic differences in cardiomyocytes derived from isogenic human induced pluripotent stem cells (hiPSC-CMs) genetically edited to harbor mutations either within the pore or tail region of the ion channel. Electrophysiological analysis confirmed that the mutations prolonged repolarization of the hiPSC-CMs, with differences between the mutations evident in monolayer cultures. Blocking the hERG channel revealed that the pore-loop mutation conferred greater susceptibility to arrhythmic events. These findings showed that subtle phenotypic differences related to KCNH2 mutations could be captured by hiPSC-CMs under genetically matched conditions. Moreover, the results support hiPSC-CMs as strong candidates for evaluating the underlying severity of individual KCNH2 mutations in humans, which could facilitate patient risk stratification., Graphical Abstract, Highlights • Mutation-specific differences detected in hiPSC-CMs with same genetic background • APD and FPD in the hERG pore variant hiPSC-CMs more prolonged than the tail variant • The pore variant was also more susceptible to drug-induced arrhythmic events • Potential strategy to determine KCNH2 mutation-specific arrhythmic risk, In this article, Davis and colleagues showed that, by studying on the same genetic background different KCNH2 mutations that can cause LQT2, subtle molecular and electrophysiological differences related to the specific mutation were captured by the corresponding hiPSC-CMs; raising the possibility of using hiPSC-CMs to model mutation-location differences observed in LQT2 patients and thereby assist in patient risk stratification.