Vertebrae patterning during regeneration

The backbone or vertebral column is a highly segmented structure which is specified during embryonic development through a process called somitogenesis. Somitogenesis divides a vertebrate embryo into individual segments, and templates the segmentation of muscles and vertebrae, following the same path in all vertebrates from the cartilaginous fish such as the little skate, to mouse and humans. However, recent studies suggest that additional modes of somite- independent segmentation could exist for vertebrae. For example, the segmentation program of zebrafish depends on the notochord, a flexible rod made of a tissue similar to cartilage, which runs through the body and gives it structure. The axolotl is a highly regenerative salamander and ideally suited to investigate the program of somite-independent vertebrae regeneration. Axolotls can regenerate segmented vertebrae after tail loss as well as in response to a local vertebrae injury. In our project, we will investigate the mechanism that axolotls use to regenerate segmented vertebrae. We will try to identify the cellular source of regenerating vertebrae in axolotl, find the tissues and factors that induce vertebrae formation during regeneration, and unveil the molecular cues that underlie vertebrae segmentation during regeneration. We hope to uncover fundamentally new mechanisms through which vertebrae are segmented, which would not only teach us more about the evolution of body plans and development, but also have the potential to contribute to innovative therapies for spinal injuries.