Generation of FOXJ1-EGFP knock-in reporter human embryonic stem cell line, WAe001-A-2D, using CRISPR/Cas9-based gene targeting.

Forkhead box protein J1 (FOXJ1), a member of the forkhead family, is an important transcription factor regulating multiciliated cell differentiation and motile ciliogenic program. Here, we established a FOXJ1- EGFP knock-in human embryonic stem cell (hESC) line by inserting a P2A-EGFP gene cassette of FOXJ1 using CRISPR/Cas9 system. The reporter cell line retained a normal karyotype, expressed comparable pluripotent marker genes, and maintained differentiation potential. This reporter cell line enables live identification of multiciliated cells during the general lung differentiation and will be a valuable tool for studying the multiciliated cell differentiation, ciliogenesis and mechanism of related pulmonary diseases.

Generation of ASCL1-mCherry knock-in reporter in human embryonic stem cell line, WAe001-A-2E, using CRISPR/Cas9-based gene targeting.

Achaete-Scute Complex Homolog 1 (ASCL1) is a key regulator in the development and function of the nervous system, particularly in the process of neuronal and neuroendocrine cell differentiation. By employing the CRISPR/Cas9 system, we successfully established an ASCL1-mCherry knock-in human embryonic stem cell (hESC) line by inserting a P2A-mCherry fragment at the ASCL1 locus. The mCherry reporter effectively demonstrated the expression level of endogenous ASCL1 during the process of inducing pulmonary neuroendocrine cells (PNECs) from hESC. This reporter cell line holds significant value as a research tool for investigating the process of lung neuroendocrine cell differentiation, conducting drug screening, and exploring the underlying mechanisms of lung diseases associated with PNECs dysfunction.

The C2 and PH domains of CAPS constitute an effective PI(4,5)P2-binding unit essential for Ca2+-regulated exocytosis.

Ca2+-dependent activator proteins for secretion (CAPSs) are required for Ca2+-regulated exocytosis in neurons and neuroendocrine cells. CAPSs contain a pleckstrin homology (PH) domain that binds PI(4,5)P2-membrane. There is also a C2 domain residing adjacent to the PH domain, but its function remains unclear. In this study, we solved the crystal structure of the CAPS-1 C2PH module. The structure showed that the C2 and PH tandem packs against one another mainly via hydrophobic residues. With this interaction, the C2PH module exhibited enhanced binding to PI(4,5)P2-membrane compared with the isolated PH domain. In addition, we identified a new PI(4,5)P2-binding site on the C2 domain. Disruption of either the tight interaction between the C2 and PH domains or the PI(4,5)P2-binding sites on both domains significantly impairs CAPS-1 function in Ca2+-regulated exocytosis at the Caenorhabditis elegans neuromuscular junction (NMJ). These results suggest that the C2 and PH domains constitute an effective unit to promote Ca2+-regulated exocytosis.