title: Live imaging of apoptosis in a novel transgenic mouse highlights its role in neural tube closure.
abstract: Many cells die during development, tissue homeostasis, and disease. Dysregulation of apoptosis leads to cranial neural tube closure (NTC) defects like exencephaly, although the mechanism is unclear. Observing cells undergoing apoptosis in a living context could help elucidate their origin, behavior, and influence on surrounding tissues, but few tools are available for this purpose, especially in mammals. In this paper, we used insulator sequences to generate a transgenic mouse that stably expressed a genetically encoded fluorescence resonance energy transfer (FRET)-based fluorescent reporter for caspase activation and performed simultaneous time-lapse imaging of apoptosis and morphogenesis in living embryos. Live FRET imaging with a fast-scanning confocal microscope revealed that cells containing activated caspases showed typical and nontypical apoptotic behavior in a region-specific manner during NTC. Inhibiting caspase activation perturbed and delayed the smooth progression of cranial NTC, which might increase the risk of exencephaly. Our results suggest that caspase-mediated cell removal facilitates NTC completion within a limited developmental window.
authors.affiliation: Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. bunbun@mol.f.u-tokyo.ac.jp
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Naomi
authors.initials: N
authors.lastname: Shinotsuka
authors.forename: Keiko
authors.initials: K
authors.lastname: Nonomura
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Takemoto
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kuida
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yosida
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miura
mesh_terms: D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D005260:Female; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D038101:Insulator Elements; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods*; D009024:Morphogenesis; D054259:Neural Tube / Q000196:embryology* / Q000378:metabolism; D009436:Neural Tube Defects / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D054261:Neurulation; D059008:Time-Lapse Imaging / Q000379:methods*
chemical_list: D020169:Caspases