Identifying deer antler uhrf1 proliferation and s100a10 mineralization genes using comparative RNA-seq

Evaluation of candidate reference genes for quantitative real-time PCR normalization in blood from red deer developing antlers

Sexual selection favors male traits that increase their ability to monopolize the breeding access to several females. Deer antlers are cranial appendages that regenerate annually in males. Throughout life, the phenology of antler growth advances and antler mass increases until the stag reaches, between 8 and 10 years old, maximum body mass and highest reproductive success. The molecular mechanisms of antler development are of great interest in both evolutionary and regenerative medicine studies. To minimize errors in the assessment of gene expression levels by qRT-PCR, we analyzed the stability of a panel of eight candidate reference genes and concluded that qRT-PCR normalization to three stable genes is strongly convenient in experiments performed in red deer antler blood. To validate our proposal, we compared the expression level of three genes linked to red deer antler growth (ANXA2, APOD and TPM1) in fifteen male red deer classified as young (up to 4 years old) and adults (4–6 years old). Our data confirms that B2M, ACTB and RPLP0 are valuable reference genes for future gene expression studies in red deer antler blood, which would provide increased insight into the effects of intrinsic factors that determine antler development in red deer.

Tenogenic induction of human adipose-derived stem cells by soluble tendon extracellular matrix: composition and transcriptomic analyses

Background

Tendon healing is clinically challenging largely due to its inferior regenerative capacity. We have previously prepared a soluble, DNA-free, urea-extracted bovine tendon-derived extracellular matrix (tECM) that exhibits strong pro-tenogenic bioactivity on human adipose-derived stem cells (hASCs). In this study, we aimed to elucidate the mechanism of tECM bioactivity via characterization of tECM protein composition and comparison of transcriptomic profiles of hASC cultures treated with tECM versus collagen type I (Col1) as a control ECM component.

Methods

The protein composition of tECM was characterized by SDS-PAGE, hydroxyproline assay, and proteomics analysis. To investigate tECM pro-tenogenic bioactivity and mechanism of action, differentiation of tECM-treated hASC cultures was compared to serum control medium or Col1-treated groups, as assessed via immunofluorescence for tenogenic markers and RNA Sequencing (RNA-Seq).

Results

Urea-extracted tECM yielded consistent protein composition, including collagens (20% w/w) and at least 17 non-collagenous proteins (< 100 kDa) based on MS analysis. Compared to current literature, tECM included key tendon ECM components that are functionally involved in tendon regeneration, as well as those that are involved in similar principal Gene Ontology (GO) functions (ECM-receptor interaction and collagen formation) and signaling pathways (ECM-receptor interaction and focal adhesion). When used as a cell culture supplement, tECM enhanced hASC proliferation and tenogenic differentiation compared to the Col1 and FBS treatment groups based on immunostaining of tenogenesis-associated markers. Furthermore, RNA-Seq analysis revealed a total of 584 genes differentially expressed among the three culture groups. Specifically, Col1-treated hASCs predominantly exhibited expression of genes and pathways related to ECM-associated processes, while tECM-treated hASCs expressed a mixture of ECM- and cell activity-associated processes, which may explain in part the enhanced proliferation and tenogenic differentiation of tECM-treated hASCs.

Conclusions

Our findings showed that urea-extracted tECM contained 20% w/w collagens and is significantly enriched with other non-collagenous tendon ECM components. Compared to Col1 treatment, tECM supplementation enhanced hASC proliferation and tenogenic differentiation as well as induced distinct gene expression profiles. These findings provide insights into the potential mechanism of the pro-tenogenic bioactivity of tECM and support the development of future tECM-based approaches for tendon repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03038-0.

Bioactive Molecular Discovery Using Deer Antlers as a Model of Mammalian Regeneration

The ability to activate and regulate stem cells during wound healing and tissue regeneration is a promising field that is resulting in innovative approaches in the field of regenerative medicine. The regenerative capacity of invertebrates has been well documented; however, in mammals, stem cells that drive organ regeneration are rare. Deer antlers are the only known mammalian structure that can annually regenerate to produce a tissue containing dermis, blood vessels, nerves, cartilage, and bone. The neural crest derived stem cells that drive this process result in antlers growing at up to 2 cm/day. Deer antlers thus provide superior attributes compared to lower-order animal models, when investigating the regulation of stem cell-based regeneration. Antler stem cells can therefore be used as a model to investigate the bioactive molecules, biological processes, and pathways involved in the maintenance of a stem cell niche, and their activation and differentiation during organ formation. This review examines stem cell-based regeneration with a focus on deer antlers, a neural crest stem cell-based mammalian regenerative structure. It then discusses the omics technical platforms highlighting the proteomics approaches used for investigating the molecular mechanisms underlying stem cell regulation in antler tissues.

New physiological insights into the phenomena of deer antler: A unique model for skeletal tissue regeneration

Generally, mammals are unable to regenerate complex tissues and organs however the deer antler provides a rare anomaly to this rule. This osseous cranial appendage which is located on the frontal bone of male deer is capable of stem cell-based organogenesis, annual casting, and cyclic de novo regeneration. A series of recent studies have classified this form of regeneration as epimorphic stem cell based. Antler renewal is initiated by the activation of neural crest derived pedicle periosteal cells (PPCs) found residing within the pedicle periosteum (PP), these PPCs have the potential to differentiate into multiple lineages. Other antler stem cells (ASCs) are the reserve mesenchymal cells (RMCs) located in the antlers tip, which develop into cartilage tissue. Antlerogenic periosteal cells (APCs) found within the antlerogenic periosteum (AP) form the tissues of both the pedicle and first set of antlers. Antler stem cells (ASCs) further appear to progress through various stages of activation, this coordinated transition is considered imperative for stem cell-based mammalian regeneration. The latest developments have shown that the rapid elongation of the main beam and antler branches are a controlled form of tumour growth, regulated by the tumour suppressing genes TP73 and ADAMTS18. Both osteoclastogenesis, as well as osteogenic and chondrogenic differentiation are also involved. While there remains much to uncover this review both summarises and comprehensively evaluates our existing knowledge of tissue regeneration in the deer antler. This will assist in achieving the goal of in vitro organ regeneration in humans by furthering the field of modern regenerative medicine.

The Translational potential of this article

As a unique stem cell-based organ regeneration process in mammals, the deer antler represents a prime model system for investigating mechanisms of regeneration in mammalian tissues. Novel ASCs could provide cell-based therapies for regenerative medicine and bone remodelling for clinical application. A greater understanding of this process and a more in-depth defining of ASCs will potentiate improved clinical outcomes.

PTN-PTPRZ signalling is involved in deer antler stem cell regulation during tissue regeneration

A growing deer antler contains a stem cell niche that can drive endochondral bone regeneration at up to 2 cm/day. Pleiotrophin (PTN), as a multifunctional growth factor, is found highly expressed at the messenger RNA level within the active antler stem cell tissues. This study aims to map the expression patterns of PTN protein and its receptors in a growing antler and investigate the effects of PTN on antler stem cells in vitro. Immunohistochemistry was employed to localise PTN/midkine (MDK) and their functional receptors, protein tyrosine phosphatase receptor type Z (PTPRZ), anaplastic lymphoma kinase (ALK), NOTCH2, and integrin α_V β_3, on serial slides of the antler growth centre. PTN was found to be the dominantly expressed growth factor in the PTN/MDK family. High expression of PTPRZ and ALK co-localised with PTN was found suggesting a potential interaction. The high levels of PTN and PTPRZ reflected the antler stem cell activation status during the regenerative process. When antler stem cells were cultured in vitro under the normoxic condition, no PTN protein was detected and exogenous PTN did not induce differentiation or proliferation but rather stem cell maintenance. Collectively, the antler stem cell niche appears to upregulate PTN and PTPRZ in vivo, and PTN-PTPRZ signalling may be involved in regulating antler stem cell behaviour during rapid antler regeneration.

Tendon-derived extracellular matrix induces mesenchymal stem cell tenogenesis via an integrin/transforming growth factor-β crosstalk-mediated mechanism

Treatment of tendon injuries is challenging. To develop means to augment tendon regeneration, we have previously prepared a soluble, low immunogenic (DNA-free), tendon extracellular matrix fraction (tECM) by urea extraction of juvenile bovine tendons, which is capable of enhancing transforming growth factor-β (TGF-β) mediated tenogenesis in human adipose-derived stem cells (hASCs). Here, we aimed to elucidate the mechanism of tECM-driven hASC tenogenic differentiation in vitro, focusing on the integrin and TGF-β/SMAD pathways. Our results showed that tECM promoted hASC proliferation and tenogenic differentiation in vitro based on tenogenesis-associated markers. tECM also induced higher expression of several integrin subunits and TGF-β receptors, and nuclear translocation of p-SMAD2 in hASCs. Pharmacological inhibition of integrin-ECM binding, focal adhesion kinase (FAK) signaling, or TGF-β signaling independently led to compromised pro-tenogenic effects of tECM and actin fiber polymerization. Additionally, integrin blockade inhibited tECM-driven TGFBR2 expression, while inhibiting TGF-β signaling decreased tECM-mediated expression of integrin α1, α2, and β1 in hASCs. Together, these findings suggest that the strong pro-tenogenic bioactivity of tECM is regulated via integrin/TGF-β signaling crosstalk. Understanding how integrins interact with signaling by TGF-β and/or other growth factors (GFs) within the tendon ECM microenvironment will provide a rational basis for an ECM-based approach for tendon repair.

Deciphering the potential pharmaceutical mechanism of Guzhi Zengsheng Zhitongwan on rat bone and kidney based on the "kidney governing bone" theory

BACKGROUND

Guzhi Zengsheng Zhitongwan (GZZSZTW) is an effective Chinese medicinal formulation for the treatment of osteoarthritis (OA) designed according to the "kidney governing bone" theory, which has been widely used as a golden guide for treating bone and cartilage diseases in traditional Chinese medicine. The aim of this study was to explore the molecular mechanism underlying its effects on the bone and kidney.

METHODS

Preparation and quality control were performed as previously described. Since GZZSZTW is orally administered in the form of pills prepared in boiled water, the Chinese materia medica (CMM) mixture of this formula was extracted with distilled water by a reflux method and was then filtered through a 0.45-μm Hollow Fiber Cartridge (GE Healthcare, USA). The filtrate was freeze-dried by a Heto PowerDry LL3000 Freeze Dryer (Thermo, USA) and stored at - 80 °C. The effects of GZZSZTW on gene expression and regulation of both kidney and bone tissues were investigated using a state-of-the-art RNA-seq technology.

RESULTS

We demonstrated that GZZSZTW could enhance kidney function and suppress bone formation and resorption by modulating the activities of osteoblast and osteoclast, and might subsequently contribute to the inhibition of osteophyte formation during the process of OA. These effects might be achieved by the synergistic interactions of various herbs and their active components in GZZSZTW, which increased the expression levels of functional genes participating in kidney function, regulation, and repair, and then decreased the expression levels of genes involved in bone formation and resorption. Thus, our findings were consistent with the "kidney governing bone" theory, which has been widely used as a guide in clinical practice for thousands of years.

CONCLUSIONS

This study has deepened the current knowledge about the molecular effects of GZZSZTW on bone and kidney regulation. Furthermore, this study might be able to provide possible strategies to further prevent and treat joint diseases by using traditional Chinese medicinal formulations following the "kidney governing bone" theory.

Antlers - Evolution, development, structure, composition, and biomechanics of an outstanding type of bone

Antlers are bony appendages of deer that undergo periodic regeneration from the top of permanent outgrowths (the pedicles) of the frontal bones. Of the "less familiar" bone types whose study was advocated by John Currey to gain a better understanding of structure-function relationships of mineralized tissues and organs, antlers were of special interest to him. The present review summarizes our current knowledge about the evolution, development, structure, mineralization, and biomechanics of antlers and how their formation is affected by environmental factors like nutrition. Furthermore, the potential role of antlers as a model in bone biology and several fields of biomedicine as well as their use as a monitoring tool in environmental studies are discussed.