Proteomic analysis of the skin from Chinese fire-bellied newt and comparison to Chinese giant salamander

Improvement of skin wound healing by giant salamander skin mucus gel wrapped with bone marrow mesenchymal stem cells via affecting integrin family molecules

BACKGROUND

Traditional bandages, gauze, and cotton balls are increasingly insufficient for addressing complex war injuries characterized by severe bleeding and diverse wound conditions. The giant salamander, a species of high medical value, secretes a unique mucus when stimulated, which has potential applications in wound care.

MATERIALS

Giant salamander skin mucus gel dressing wrapped with bone marrow mesenchymal stem cells (BMSCs-GSSM-gel) was prepared and validated. Skin wound injury of rabbit and mouse models were established. Hematoxylin and Eosin, Masson's trichrome, and Sirius red staining were performed. The platelet aggregation rate and coagulation items were measured. Transcriptome sequencing was performed to find potential differential expression genes.

RESULTS

Preparation and characterization of BMSCs-GSSM-gel were performed, and BMSCs-GSSM-gel particles with a diameter of about 200 nm were obtained. BMSCs-GSSM-gel accelerated wound healing in both rabbit and mouse models. BMSCs-GSSM-gel significantly promoted hemostasis via increasing platelet aggregation rate and fibrinogen, but decreasing activated partial thromboplastin time, thrombin time, and prothrombin time. BMSCs-GSSM-gel treatment significantly impacted several genes associated with cell adhesion, inflammatory response, collagen-containing extracellular matrix, and the positive regulation of cell migration based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Integrin Subunit Beta 4 (ITGB4), Integrin Subunit Alpha 3 (ITGA3), and Laminin Subunit Beta 3 (LAMB3) might be involved in the wound healing process by BMSCs-GSSM-gel.

CONCLUSIONS

We proved the BMSCs-GSSM-gel greatly improved the skin wound healing, and it might play a crucial role in the application fields of skin damage repair.

Full-length transcriptome assembly of Andrias davidianus (Amphibia: Caudata) skin via hybrid sequencing

The Chinese giant salamander, Andrias davidianus, is the largest amphibian species in the world; it is thus an economically and ecologically important species. The skin of A. davidianus exhibits complex adaptive structural and functional adaptations to facilitate survival in aquatic and terrestrial ecosystems. Here, we report the first full-length amphibian transcriptome from the dorsal skin of A. davidianus, which was assembled using hybrid sequencing and the PacBio and Illumina platforms. A total of 153,038 transcripts were hybrid assembled (mean length of 2039 bp and N50 of 2172 bp), and 133,794 were annotated in at least one database (nr, Swiss-Prot, KEGG, KOGs, GO, and nt). A total of 58,732, 68,742, and 115,876 transcripts were classified into 24 KOG categories, 1903 GO term categories, and 46 KEGG pathways (level 2), respectively. A total of 207,627 protein-coding regions, 785 transcription factors, 27,237 potential long non-coding RNAs, and 8299 simple sequence repeats were also identified. The hybrid-assembled transcriptome recovered more full-length transcripts, had a higher N50 contig length, and a higher annotation rate of unique genes compared with that assembled in previous studies using next-generation sequencing. The high-quality full-length reference gene set generated in this study will help elucidate the genetic characteristics of A. davidianus skin and aid the identification of functional skin proteins.

Proteomic analysis of eleven tissues in the Chinese giant salamander (Andrias davidianus)

The Chinese giant salamander (Andrias davidianus, CGS) is the largest extant amphibian species in the world. Global quantitative proteome analysis of multiple tissues would indicate tissue-specific physiological processes and clarify the function of each protein from a whole-organism perspective. This study performed proteome analysis of eleven tissues collected from adult CGSs using iTRAQ coupled with LC-MS/MS technology. Based on the predicted protein database from previously obtained CGS transcriptome data, 2153 proteins were identified for subsequent analysis. A weighted gene co-expression network analysis (WGCNA) clustered 2153 proteins into 17 co-expressed modules, which will be useful for predicting the functions of unannotated proteins. The protein levels of molecular complexes with housekeeping functions, such as ribosomes, spliceosomes and mitochondrial respiratory chain complexes, were tightly regulated in different tissues of the CGS, as they are in mammalian tissues. Transcription regulator, pathway and bio-functional analysis of tissue-specific proteins showed that highly expressed proteins largely reflected the physiological functions of specific tissues. Our data, as an initial atlas of protein expression of an amphibian species, will be useful for further molecular biology research on CGS.

Molecular characterisation of oestrogen receptor ERα and the effects of bisphenol A on its expression during sexual development in the Chinese giant salamander (Andrias davidianus)

The aim of this study was to characterise the molecular structure of the oestrogen receptor ERα and to evaluate the effect of bisphenol A (BPA) on ERα expression during sexual development of the Chinese giant salamander (Andrias davidianus). The ERα cDNA of A. davidianus includes an open reading frame of 1755bp (encoding 584 amino acids), a 219-bp 5' untranslated region (UTR) and a 611-bp 3'UTR. A polyadenylation signal was not found in the 3'UTR. Amino acid sequence analysis showed high homology between ERα of A. davidianus and that of other amphibians, such as Andrias japonicas (99.66% identity) and Rana rugose (81.06% identity). In 3-year-old A. davidianus, highest ERα expression was observed in the liver and gonads. During different developmental stages in A. davidianus (from 1 to 3 years of age), ERα expression in the testes increased gradually. ERα was localised in the epithelial cells of seminiferous lobules and in interstitial cells. ERα-positive cells were more abundant in the interstitial tissue during testicular development. ERα was located in the nucleus of oocytes during ovary development. We found that the sex of 6-month-old A. davidianus larvae could not be distinguished anatomically. The sex ratio did not change after larvae were treated with 10μM BPA for 1 month. However, BPA treatment reduced bodyweight and ERα expression in the gonads in male larvae.

UCHL1 expression and localization on testicular development and spermatogenesis of Chinese giant salamanders

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), which is extensively expressed in vertebrates, is a deubiquitinating enzymes that inhibits the degradation of proteins by reversing ubiquitination modification. Herein, a 1087-bp sequence encoding UCHL1 was identified from the Chinese giant salamander (CGS; Andrias davidianus). The coding sequences (CDS) of UCHL1 encoded a putative poly peptide of 222 amino acids. The CGS UCHL1 isoforms were more related to their human and mouse counterparts. The phylogenic tree of vertebrate UCHL1 indicated that CGS UCHL1 has the closest relationship with human UCHL1 (up to 73.99 %). Before the gonads of male CGSs matured, the peak level of UCHL1 expression in testes appeared in 3-year-old CGSs according to RT-qPCR and western blot. In adult testes, the level of UCHL1 protein was lower in the breeding period than in the post-breeding period, whereas the level of UCHL1 protein in interstitial fluid of adult CGS testes was higher during the breeding period than during the post-breeding period. In testicular seminiferous lobules in the developmental stage of CGSs, immunohistochemistry displayed three kinds of localizing patterns of UCHL1, including nuclear localization at half year old, cytoplasmic localization from one year to three years old, and extracellular localization in adult. In testicular seminiferous lobules of adult CGS, the different developmental germ cells were separated by cysts containing UCHL1 protein, but UCHL1 did not localize on the mature sperm. The results showed that extracellular UCHL1 loaded on exosomes, as a component of the homogeneous germ cell cysts, could regulate the synchronous development of sperm in testes of adult CGS.