Proteomic Analysis of Plasma Membrane Proteins of Antler Stem Cells Using Label-Free LC⁻MS/MS

Antler stem cells and their potential in wound healing and bone regeneration

Compared to other vertebrates, the regenerative capacity of appendages in mammals is very limited. Deer antlers are an exception and can fully regenerate annually in postnatal mammals. This process is initiated by the antler stem cells (AnSCs). AnSCs can be divided into three types: (1) Antlerogenic periosteum cells (for initial pedicle and first antler formation); (2) Pedicle periosteum cells (for annual antler regeneration); and (3) Reserve mesenchyme cells (RMCs) (for rapid antler growth). Previous studies have demonstrated that AnSCs express both classic mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs), and are able to differentiate into multiple cell types in vitro. Thus, AnSCs were defined as MSCs, but with partial ESC attributes. Near-perfect generative wound healing can naturally occur in deer, and wound healing can be achieved by the direct injection of AnSCs or topical application of conditioned medium of AnSCs in rats. In addition, in rabbits, the use of both implants with AnSCs and cell-free preparations derived from AnSCs can stimulate osteogenesis and repair defects of bone. A more comprehensive understanding of AnSCs will lay the foundation for developing an effective clinical therapy for wound healing and bone repair.

Protective Activity of Aspirin Eugenol Ester on Paraquat-Induced Cell Damage in SH-SY5Y Cells

Aspirin eugenol ester (AEE) is a new pharmaceutical compound esterified by aspirin and eugenol, which has anti-inflammatory, antioxidant, and other pharmacological activities. The aim of this study was to investigate the protective effect of AEE on paraquat- (PQ-) induced cell damage of SH-SY5Y human neuroblastoma cells and its potential molecular mechanism. There was no significant change in cell viability when AEE was used alone. PQ treatment reduced cell viability in a concentration-dependent manner. However, AEE reduced the PQ-induced loss of cell viability. Flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and 4′6-diamidino-2-phenylindole (DAPI) staining were used to evaluate cell apoptosis. Compared with the PQ group, AEE pretreatment could significantly inhibit PQ-induced cell damage. AEE pretreatment could reduce the cell damage of SH-SY5Y cells induced by PQ via reducing superoxide anion, intracellular reactive oxygen species (ROS), and mitochondrial ROS (mtROS) and increasing the levels of mitochondrial membrane potential (ΔΨm). At the same time, AEE could increase the activity of glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD) and decrease the activity of malondialdehyde (MDA). The results showed that compared with the control group, the expression of p-PI3K, p-Akt, and Bcl-2 was significantly decreased, while the expression of caspase-3 and Bax was significantly increased in the PQ group. In the AEE group, AEE pretreatment could upregulate the expression of p-PI3K, p-Akt, and Bcl-2 and downregulate the expression of caspase-3 and Bax in SH-SY5Y cells. PI3K inhibitor LY294002 and the silencing of PI3K by shRNA could weaken the protective effect of AEE on PQ-induced SH-SY5Y cells. Therefore, AEE has a protective effect on PQ-induced SH-SY5Y cells by regulating the PI3K/Akt signal pathway to inhibit oxidative stress.

SWATH-MS Quantitative Proteomic Analysis of Deer Antler from Two Regenerating and Mineralizing Sections

Simple Summary

Deer antler is a unique and astonishing case of annual regeneration in mammalians. Several studies have pointed out the potential for use of velvet antler extract as a nutraceutical supplement, among others, because of its anti-cancer activity. The study of antler regeneration and growth allow us to identify the main proteins and regulatory pathways involved in cell differentiation and regeneration. For this purpose, two sections of antlers (tips and middle sections) using ribs as controls were analyzed from a proteomic point of view. A total of 259 proteins mainly associated with antioxidant mechanisms and Wnt signalling pathways could be responsible for deer antler regeneration and these proteins may be linked to human health benefits. Further studies should be focused on discovering which proteins from velvet antler extracts are associated with these beneficial effects.

Abstract

Antlers are the only organ in the mammalian body that regenerates each year. They can reach growth rates of 1–3 cm/day in length and create more than 20 cm²/day of skin in the antler tips (their growth centers). Previous proteomic studies regarding antlers have focused on antler growth centers (tips) compared to the standard bone to detect the proteins involved in tissue growth. However, proteins of cell differentiation and regeneration will be more accurately detected considering more growing tissues. Thus, we set out to compare proteins expressed in antler tips (the highest metabolism rate and cell differentiation) vs. middle sections (moderate cell growth involving bone calcification), using ribs as controls. Samples were obtained in mid-June with antlers’ phenology corresponding to the middle of their growth period. Quantitative proteomic analysis identified 259 differentially abundant proteins mainly associated with antioxidant metabolic mechanisms, protein formation and Wnt signalling pathway, meanwhile, the mid antler section was linked to blood proteins. The high metabolic rate and subsequent risk of oxidative stress also seem to have resulted in strong antioxidant mechanisms. These results suggest that redox regulation of proteins is a key factor in the model of deer antler regeneration.

The Protective Effect of Aspirin Eugenol Ester on Oxidative Stress to PC12 Cells Stimulated with H2O2 through Regulating PI3K/Akt Signal Pathway

Aspirin eugenol ester (AEE) is a new pharmaceutical compound esterified by aspirin and eugenol, which has anti-inflammatory, antioxidant, and other pharmacological activities. This study is aimed at identifying the protective effect of AEE against H₂O₂-induced apoptosis in rat adrenal pheochromocytoma PC12 cells and the possible mechanisms. The results of cell viability assay showed that AEE could increase the viability of PC12 cells stimulated by H₂O₂, while AEE alone had no significant effect on the viability of PC12 cells. Compared with the control group, the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were significantly decreased, and the content of malondialdehyde (MDA) was significantly increased in the H₂O₂ group. By AEE pretreatment, the level of MDA was reduced and the levels of SOD, CAT, and GSH-Px were increased in H₂O₂-stimulated PC12 cells. In addition, AEE could reduce the apoptosis of PC12 cells induced by H₂O₂ via reducing superoxide anion, intracellular ROS, and mitochondrial ROS (mtROS) and increasing the levels of mitochondrial membrane potential (ΔΨm). Furthermore, the results of western blotting showed that compared with the control group, the expression of p-PI3K, p-Akt, and Bcl-2 was significantly decreased, while the expression of Caspase-3 and Bax was significantly increased in the H₂O₂ group. In the AEE group, AEE pretreatment could upregulate the expression of p-PI3K, p-Akt, and Bcl-2 and downregulate the expression of Caspase-3 and Bax in PC12 cells stimulated with H₂O₂. The silencing of PI3K with shRNA and its inhibitor-LY294002 could abrogate the protective effect of AEE in PC12 cells. Therefore, AEE has a protective effect on H₂O₂-induced PC12 cells by regulating the PI3K/Akt signal pathway to inhibit oxidative stress.

LncRNA WDFY3-AS2 promotes cisplatin resistance and the cancer stem cell in ovarian cancer by regulating hsa-miR-139-5p/SDC4 axis

BACKGROUND

Ovarian cancer (OC) is a high-mortality gynecological cancer that is typically treated with cisplatin, although such treatment often results in chemoresistance. Ovarian cancer resistance is usually related to cell stemness. Herein, we explored the function of lncRNA WDFY3-AS2 in OC cell resistance to cisplatin (DDP).

METHODS

Cisplatin resistant OC A2780 cell lines (A2780-DDP) were established by long-term exposure to cisplatin. CCK-8 assay were performed to evaluate the viability of A2780, and A2780-DDP cells. Quantitative RT-PCR was used to examine the expression of lncRNA WDFY3-AS2, miR-139-5p, and SDC4 in A2780-DDP cell lines. After treatment with cisplatin, cell apoptosis and CD44+CD166+-positive cells were measured by flow cytometry. The transwell assays were employed to measure the effect of WDFY3-AS2 on cell migration, and invasion. In addition, tumorsphere formation assay was used to enrich OC cancer stem cells (CSCs) from A2780-DDP cells. The expression of CSC markers (SOX2, OCT4, and Nanog) was detected by western blotting. The regulatory mechanism was confirmed by RNA pull down, and luciferase reporter assays. Furthermore, xenograft tumor in nude mice was used to assess the impact of WDFY3-AS2 on cisplatin resistance in OC in vivo.

RESULTS

WDFY3-AS2 was highly expressed in OC A2780-DDP cells, and silencing WDFY3-AS2 significantly inhibited proliferation, migration and invasion but increased apoptosis in OC A2780-DDP cells. Additionally, WDFY3-AS2 significantly promoted the A2780-DDP cells tumorspheres. WDFY3-AS2 was predicted to impact OC by sponging miR-139-5p and regulating SDC4. The xenografts inoculated with A2780-DDP cells additionally confirmed that tumor growth in vivo was reduced by si-WDFY3-AS2 transfection. MiR-139-5p inhibitor or SDC4 overexpression could restore the suppressive influence of silenced WDFY3-AS2 on tumor growth.

CONCLUSIONS

Together, WDFY3-AS2 may lead to change of cisplatin resistance by the expression of miR-139-5p/SDC4 in the OC A2870-DDP cells both in vitro and in vivo. Our finding may provide a drug target for the drug resistance of OC.

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.

Transcriptome analysis identifies the differentially expressed genes related to the stemness of limbal stem cells in mice

Limbal stem cells (LSCs) reside in the basal layer of limbal epithelial cells (LECs). They are crucial for maintenance of corneal epithelium homeostasis and corneal wound healing. Their stemness is determined by their gene expression pattern. Despite of several positive identifiers have been reported, the unique biomarker for LSCs still remain elusive. Differentially expressed genes (DEGs) between stem cells and differentiated cells affect the fate of stem cells via specific signaling pathway. In order to understand the DEGs in the LSCs, RNA-seq was firstly conducted using a mouse model. A total of 1907 up-regulated DEGs and 395 down-regulated DEGs were identified in the limbus (L) compared to central cornea (CC) and conjunctiva (Cj). Reliability of the expression of genes from RNA-seq analysis was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence staining. The expression pattern of putative biomarkers was considered to be age-related. In up-regulated DEGs GO analysis, 570 gene ontology (GO) terms were significantly enriched. Five groups of genes related with biological processes from these significantly enriched GO terms comprised ionic transport, regulation of tissue development, muscle contraction, visual perception, and cell adhesion, which were clustered as a weighted similar network. Whereas, in down-regulated DEGs GO analysis, 61 GO terms were significantly enriched and only one group of ATP biosynthesis and metabolic process were clustered. Furthermore, we identified 55 signaling pathways by the Kyoto Encyclopedia of Genes and Genomes (KEGG) database based on up-regulated genes and 14 KEGG pathways based on down-regulated genes. In this study, we provide a landscape of the expression of putative LSCs biomarkers and stemness-related signaling pathways in a mouse model. Our findings could aid in the identification of LSC niche factors that may be related to the stemness of the LSCs.

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.

Identification of proteins that mediate the role of androgens in antler regeneration using label free proteomics in sika deer (Cervus nippon)

Deer antlers offer a unique model to study organ regeneration in mammals. Antler regeneration relies on the pedicle periosteum (PP) cells and is triggered by a decrease in circulating testosterone (T). The molecular mechanism for antler regeneration is however, unclear. Label-free liquid chromatography-mass spectrometry (LC-MS/MS) was used to identify differentially-expressed proteins (DEPs) in the regeneration-potentiated PP (under low T environment) over the non-regeneration-potentiated PP (under high T environment). Out of total 273 DEPs, 189 were significantly up-regulated and 84 were down-regulated from these comparisons: after castration vs before castration, natural T vs before castration, and exogenous T vs before castration. We focused on the analysis only of those DEPs that were present in fully permissive environment to antler regeneration (low T). Nine transduction pathways were identified through the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, including the estrogen signaling pathway. A total of 639 gene ontology terms were found to be significantly enriched in regeneration-potentiated PP (low T) from the DEPs. Reliability of the label free LC-MS/MS was determined by qRT-PCR to estimate the expression level of selected genes. The results suggest that up-regulated heat shock proteins (HSP90AB1, HSP90B1), peptidyl-prolyl cis-trans isomerase 4 (FKBP4), mitogen-activated protein kinase 3 (MAPK3) and calreticulin (CALR) and down-regulated SHC-transforming protein 1 (SHC1), heat shock protein family A member 1A (HSPA1A) and proto-oncogene tyrosine-protein kinase (SRC) may be associated directly or indirectly with antler regeneration. Further studies are required to investigate the roles of these proteins in regeneration using appropriate in vivo models.