title: Vascular patterning regulates interdigital cell death by a ROS-mediated mechanism.
abstract: Blood vessels serve as key regulators of organogenesis by providing oxygen, nutrients and molecular signals. During limb development, programmed cell death (PCD) contributes to separation of the digits. Interestingly, prior to the onset of PCD, the autopod vasculature undergoes extensive patterning that results in high interdigital vascularity. Here, we show that in mice, the limb vasculature positively regulates interdigital PCD. In vivo, reduction in interdigital vessel number inhibited PCD, resulting in syndactyly, whereas an increment in vessel number and distribution resulted in elevation and expansion of PCD. Production of reactive oxygen species (ROS), toxic compounds that have been implicated in PCD, also depended on interdigital vascular patterning. Finally, ex vivo incubation of limbs in gradually decreasing oxygen levels led to a correlated reduction in both ROS production and interdigital PCD. The results support a role for oxygen in these processes and provide a mechanistic explanation for the counterintuitive positive role of the vasculature in PCD. In conclusion, we suggest a new role for vascular patterning during limb development in regulating interdigital PCD by ROS production. More broadly, we propose a double safety mechanism that restricts PCD to interdigital areas, as the genetic program of PCD provides the first layer and vascular patterning serves as the second.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Idit
authors.initials: I
authors.lastname: Eshkar-Oren
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Sharon
authors.initials: S
authors.lastname: Krief
authors.affiliation: Genentech, Inc., 1 DNA Way, S. San Francisco, CA 94080, USA.
authors.forename: Napoleone
authors.initials: N
authors.lastname: Ferrara
authors.affiliation: Departments of Pediatrics and Child Health and Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB R3A 1S1, Manitoba, Canada.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Elliott
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel eli.zelzer@weizmann.ac.il.
authors.forename: Elazar
authors.initials: E
authors.lastname: Zelzer
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology*; D005121:Extremities / Q000098:blood supply / Q000196:embryology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D051379:Mice; D009924:Organ Culture Techniques; D011247:Pregnancy; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species
keywords: Interdigit; Limb development; Oxygen; Programmed cell death; Reactive oxygen species; Syndactyly; Vascular patterning