Neural Regulation of the Cell Cycle During Limb Regeneration

Presenter: Eun Kyung Jeon

Research Category: Physical and LIfe Sciences
Student Type: Undergraduate
Additional Authors: Andy Martinez, Ken Mochizuki, Melissa Miller
PI: James Monaghan
Award Winner Category: Physical and Life Sciences

A major goal of biological research is to understand how some animals regenerate tissues such as limbs and organs. One of the most impressive examples of tissue regeneration is the complete regeneration of the salamander limb. Limb regeneration is dependent upon the presence of an intact nerve supply to the injury site. Characterizing the nature of nerve dependency is critical for understanding the mechanisms that drive regeneration. Here we studied the impact of removing nerve axons from the limb on cell proliferation in the axolotl salamander. Qualitative observations of injured limbs after the removal of nerves revealed termination of regenerative growth and regression of local tissues. Our next goal was to determine how limb denervation impacts each specific stage of the cell cycle including G1, synthesis, G2, and mitosis. Tissue sections from innervated and denervated regenerating limbs were co-stained with thymine deoxyribonucleic acid (DNA) analogs, 5-ethynyl-2’-deoxyuridine (EdU) and 5-bromo-2’-deoxyuridine (BrdU), 12 hours and 24 hours after denervation, respectively. This approach labels cells in the synthesis phase of the cell cycle to determine whether cells are stalling in G1 phase of the cell cycle. Histological analysis of the regenerating tissues showed variable quantities of cell populations stained with EdU and BrdU, preliminarily indicating that cells stall in G1 and demonstrating for the first time that we can study cell cycle kinetics during regeneration. Quantitative analysis of cell cycle kinetics using this methodology will help define the neural involvement in regenerative growth.