The development of the eyelid requires coordinated cellular processes of proliferation, cell shape changes, migration and cell death. Mutant mice deficient in the fibroblast growth factor 10 (Fgf10) gene exhibit open-eyelids at birth. To elucidate the roles of FGF10 during eyelid formation, we examined the expression pattern of Fgf10 during eyelid formation and the phenotype of Fgf10-null eyelids in detail. Fgf10 is expressed by mesenchymal cells just beneath the protruding epidermal cells of the nascent eyelid. However, Fgf10-null epithelial cells running though the eyelid groove do not exhibit typical cuboid shape or sufficient proliferation. Furthermore, peridermal clumps are not maintained on the eyelid leading edge, and epithelial extension does not occur. At the cellular level, the accumulation of actin fibers is not observed in the mutant epithelial leading edge. The expression of activin/inhibin βB(ActβB/Inhbb) and transforming growth factor α(Tgfa), previously reported to be crucial for eyelid development, is down-regulated in the mutant leading edge, while the onset of sonic hedgehog(Shh) expression is delayed on the mutant eyelid margin. Explant cultures of mouse eyelid primordia shows that the open-eyelid phenotype of the mutant is reduced by exogenous FGF10 protein, and that the expression of ActβB and Tgfa is ectopically induced in the thickened eyelid epithelium by the FGF10 protein. These results indicate a dual role of FGF10 in mouse eyelid development, for both proliferation and coordinated migration of eyelid epithelial cells by reorganization of the cytoskeleton, through the regulation of activin, TGFα and SHH signaling.
SummaryThe application of stem-cell-based therapies in regenerative medicine is hindered by the tumorigenic potential of residual human pluripotent stem cells. Previously, we identified a human pluripotent stem-cell-specific lectin probe, called rBC2LCN, by comprehensive glycome analysis using high-density lectin microarrays. Here we developed a recombinant lectin-toxin fusion protein of rBC2LCN with a catalytic domain of Pseudomonas aeruginosa exotoxin A, termed rBC2LCN-PE23, which could be expressed as a soluble form from the cytoplasm of Escherichia coli and purified to homogeneity by one-step affinity chromatography. rBC2LCN-PE23 bound to human pluripotent stem cells, followed by its internalization, allowing intracellular delivery of a cargo of cytotoxic protein. The addition of rBC2LCN-PE23 to the culture medium was sufficient to completely eliminate human pluripotent stem cells. Thus, rBC2LCN-PE23 has the potential to contribute to the safety of stem-cell-based therapies.
Sweet and umami tastes are perceived by T1r taste receptors in oral cavity. T1rs are class C G-protein coupled receptors (GPCRs), and the extracellular ligand binding domains (LBDs) of T1r1/T1r3 and T1r2/T1r3 heterodimers are responsible for binding of chemical substances eliciting umami or sweet taste. However, molecular analyses of T1r have been hampered due to the difficulties in recombinant expression and protein purification, and thus little is known about mechanisms for taste perception. Here we show the first molecular view of reception of a taste substance by a taste receptor, where the binding of the taste substance elicits a different conformational state of T1r2/T1r3 LBD heterodimer. Electron microscopy has showed a characteristic dimeric structure. Förster resonance energy transfer and X-ray solution scattering have revealed the transition of the dimerization manner of the ligand binding domains, from a widely spread to compactly organized state upon taste substance binding, which may correspond to distinct receptor functional states.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.