Conservation analysis of core cell cycle regulators and their transcriptional behavior during limb regeneration in Ambystoma mexicanum

Annie Espinal-Centeno,Carlos Saldaña,Melissa Dipp-Álvarez,Alfredo Cruz-Ramírez,Laszlo Bako

doi:10.1016/j.mod.2020.103651

Abstract

Ambystoma mexicanum (axolotl) has been one of the major experimental models for the study of regeneration during the past 100 years. Axolotl limb regeneration takes place through a multi-stage and complex developmental process called epimorphosis that involves diverse events of cell reprogramming. Such events start with dedifferentiation of somatic cells and the proliferation of quiescent stem cells to generate a population of proliferative cells called blastema. Once the blastema reaches a mature stage, cells undergo progressive differentiation into the diverse cell lineages that will form the new limb. Such pivotal cell reprogramming phenomena depend on the fine-tuned regulation of the cell cycle in each regeneration stage, where cell populations display specific proliferative capacities and differentiation status. The axolotl genome has been fully sequenced and released recently, and diverse RNA-seq approaches have also been generated, enabling the identification and conservatory analysis of core cell cycle regulators in this species. We report here our results from such analyses and present the transcriptional behavior of key regulatory factors during axolotl limb regeneration. We also found conserved protein interactions between axolotl Cyclin Dependent Kinases 2, 4 and 6 and Cyclins type D and E. Canonical CYC-CDK interactions that play major roles in modulating cell cycle progression in eukaryotes.

Highlights

In multicellular eukaryotes, most developmental processes rely on the transition between the proliferative capacity and the differentiated status of groups of cells
In addition to Mus musculus and Homo sapiens, we searched in databases available for 4 species of the Ambystoma genus (A. mexicanum, A. velasci, A. andersoni and A. mac ulatum), Xenopus laevis, Xenopus tropicalis, Anolis carolinensis, Alligator mississippiensis and Danio rerio
We identified 8 genes coding for E2F transcription factors (E2F TF) in axolotl and named them according to their similarity with the human homologs as AmE2F1, AmE2F2, AmE2F3, AmE2F4, AmE2F5, AmE2F6, AmE2F7 and AmE2F8 (Fig. 2A)

Summary

Introduction

Most developmental processes rely on the transition between the proliferative capacity and the differentiated status of groups of cells. Processes such as embryonic development, postembryonic organ and limb patterning, metamorphosis and regen eration depend on the capacity of cells to divide and to acquire a specific fate. Regeneration of tis sues, organs and limbs implies the replacement of populations of lost cells, which requires that specific remnant cells enter into a highly proliferative status. Blastema formation implies that tissue-resident stem cells and differentiated mature cells abandon their G0 status to enter and progress in the cell cycle (Sandoval-Guzman et al, 2014; Johnson et al, 2018)

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Results

Conclusion