Abstract
As the only known mammalian organ that can fully and annually regenerate, deer antler has significant advantages over lower-order animal models when investigating the control of stem-cell-based organ regeneration. Antler regeneration is known to be initiated and maintained by neural-crest-derived stem cells in different states of activation. Antler stem cells can therefore be used as a model to study proteins and pathways involved in the maintenance of a stem cell niche and their activation and differentiation during organ formation. In this study, the MSC markers CD73, CD90, and CD105 were examined within the antler tip. Label-free quantification was performed to investigate the protein profiles of antler stem cells under different stages of activation and included dormant pedicle periosteum (DPP), antler growth center (GC), post-active stem cells from mid-beam antler periosteum (MAP), and deer facial periosteum (FP) as a control (n = 3 per group). PEAKS and IPA software were used to analyze the proteomic data. Our research confirmed the central role of stem cell activation in the development of this mammalian organ by localizing the MSC markers within the antler growth center. Label-free quantification revealed that the greatest number of unique proteins (87) was found in the growth center. There were only 12 proteins found with expression levels that significantly differed between DPP and FP. Protein profiles of these two groups indicated that antler stem cells may use similar mechanisms to maintain dormancy within a stem cell niche. The number of significantly regulated proteins among DPP, MAP, and GC was 153. Among them, the majority were upregulated in the growth center. Activation of antler stem cells was associated with many biological processes and signaling pathways, such as Hippo and canonical Wnt signaling. This work identifies the key pathways, molecular/cellular functions, and upstream regulators involved in mammal organ regeneration. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the iProX partner repository with the dataset identifier PXD016824.