An EGFR gene of the Pacific oyster Crassostrea gigas functions in wound healing and promotes cell proliferation

Single-cell RNA sequencing revealed the roles of macromolecule epidermal growth factor receptor (EGFR) in the hybrid sterility of hermaphroditic Argopecten scallops

The macromolecule epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein that belongs to the protein kinase superfamily, which plays versatile functions in cell proliferation, development and fertility regulation. Almost all F1 hybrids obtained from the hermaphroditic bay scallops and Peruvian scallops exhibit infertility, and the genetic mechanism remains unclear. In this study, the comprehensive scRNA-seq was first conducted in the gonads of hybrid scallops, deducing the developmental sequence of germ cells and identifying the critical regulators in hybrid sterility: epidermal growth factor receptor. During the development from oogenesis phase germ cells to oocytes, the expression of the EGFR gene gradually decreased in sterile hybrids but increased in fertile hybrids. The significantly lower EGFR expression and ATP content, but higher ROS production rate was detected in the gonad of sterile hybrids than that in fertile hybrids, which might cause slow development of oocytes, stagnation of cell cycle, insufficient energy supply, high level of apoptosis and final sterility. Specific knock-down of EGFR gene led to decreased ATP content, increased ROS production rate, and inhibited oocyte maturation and gonadal development. These findings provide new insights into the roles of EGFR in hybrid infertility of bivalves and the healthy development of scallop breeding.

Transcriptomic responses reveal impaired physiological performance of the pearl oyster following repeated exposure to marine heatwaves

Marine heatwaves are predicted to become more intense and frequent in the future, possibly threatening the survival of marine organisms and devastating their communities. While recent evidence reveals the adaptability of marine organisms to heatwaves, substantially overlooked is whether they can also adjust to repeated heatwave exposure, which can occur in nature. By analysing transcriptome, we examined the fitness and recoverability of the pearl oyster (Pinctada maxima) after two consecutive heatwaves (24 °C to 32 °C for 3 days; recovery at 24 °C for 4 days). In the first heatwave, 331 differentially expressed genes (DEGs) were found, such as AGE-RAGE, MAPK, JAK-STAT, FoxO and mTOR. Despite the recovery after the first heatwave, 2511 DEGs related to energy metabolism, body defence, cell proliferation and biomineralization were found, where 1655 of them were downregulated, suggesting a strong negative response to the second heatwave. Our findings imply that some marine organisms can indeed tolerate heatwaves by boosting energy metabolism to support molecular defence, cell proliferation and biomineralization, but this capacity can be overwhelmed by repeated exposure to heatwaves. Since recurrence of heatwaves within a short period of time is predicted to be more prevalent in the future, the functioning of marine ecosystems would be disrupted if marine organisms fail to accommodate repeated extreme thermal stress.

Mantle Transcriptome Provides Insights into Biomineralization and Growth Regulation in the Eastern Oyster (Crassostrea virginica)

Growth of the eastern oyster Crassostrea virginica, a major aquaculture species in the USA, is highly variable and not well understood at molecular levels. As growth of mollusks is confined in shells constructed by the mantle, mantle transcriptomes of large (fast-growing) and small (slow-growing) eastern oysters were sequenced and compared in this study. Transcription was observed for 31,186 genes, among which 104 genes were differentially expressed between the large and small oysters, including 48 upregulated and 56 downregulated in large oysters. Differentially expressed genes (DEGs) included genes from diverse pathways highlighting the complexity of shell formation and growth regulations. Seventeen of the 48 upregulated DEGs were related to shell matrix formation, most of which were upregulated in large oysters, indicating that large oysters are more active in biomineralization and shell formation. Genomic and transcriptomic analyses identified 22 genes encoding novel polyalanine containing proteins (Pacps) with characteristic motifs for matrix function that are tandemly duplicated on one chromosome, all specifically expressed in mantle and at higher levels in large oysters, suggesting that these expanded Pacps play important roles in shell formation and growth. Analysis of sequence variation identified 244,964 SNPs with 328 associated with growth. This study provides novel candidate genes and markers for shell formation and growth, and suggests that genes related to shell formation are important for the complex regulation of growth in the eastern oyster and possibly other bivalve mollusks. Results of this study show that both transcriptional modulation and functional polymorphism are important in determining growth.

MiR-873-5p modulates progression of tongue squamous cell carcinoma via targeting SEC11A

OBJECTIVE

To explore the effect of miR-873-5p on proliferation, apoptosis, migration, and invasion of tongue squamous cell carcinoma (TSCC) by targeting SEC11A.

METHODS

Tongue squamous cell carcinoma tissues were collected and performed by qRT-PCR and Western blotting to determine the expression of miR-873-5p and SPC18. SCC9 and CAL-27 cells were transfected and divided into Mock, mimic NC, miR-873-5p mimic, SEC11A, and miR-873-5p mimic + SEC11A groups. Then, a series of experiments including cell count kit 8 (CCK-8), wound healing, Transwell, and flow cytometry were conducted. Besides, Western blotting was used to detect the expression of SPC18 and EGFR pathway-related proteins.

RESULTS

MiR-873-5p was downregulated while SPC18 was upregulated in TSCC, and miR-873-5p was negatively correlated with SPC18. Dual luciferase reporter gene assay confirmed SEC11A to be a target of miR-873-5p. Cell proliferation, migration, and invasion of SCC9 and CAL-27 cells in miR-873-5p mimic group were decreased with increased cell apoptosis, presenting with downregulations of SPC18 and EGFR pathway-related proteins, while cells in SEC11A group manifested totally different changes. Moreover, the inhibitory effect of miR-873-5p mimic on TSCC cell growth was abolished by SEC11A overexpression.

CONCLUSION

Overexpression of miR-873-5p may suppress cell proliferation, migration, and invasion, but facilitate apoptosis in TSCC via targeting SEC11A.

Stimulatory roles of epidermal growth factor receptor (EGFR) in ovarian development of mud crab Scylla paramamosain

The epidermal growth factor receptor (EGFR) is a pleiotropic glycoprotein which plays a role in regulating cell proliferation, migration and differentiation. However, to date little is known about its functions in crustaceans. In this study, we successfully identified SpEGFR from mud crab Scylla paramamosain. RT-PCR result showed that SpEGFR was widely distributed in all tested tissues and highly expressed in ovary. In situ hybridization revealed that SpEGFR mainly localized in oocyte perinuclear region with notably obvious signals. In vitro experiments showed that the expression of SpVgR and SpCyclin B in ovary explants from late vitellogenic stage crabs (summer) were significantly increased when treated with 1 nM human EGF (hEGF) for 1 h, while there was no obvious change towards SpEGFR. Interestingly, as for winter crab at the same vitellogenic stage, the expression of SpVgR and SpCyclin B in ovary explants did not show significant increase until treated with higher concentration of 10 nM hEGF and longer incubation time of 12 h. In addition, the hEGF-induced effect could be suppressed by pre-treated with EGFR inhibitor AG1478 and PD153035, respectively, which further indicated that EGF-EGFR pathway played a vital role in ovarian development in mud crab. In conclusion, SpEGFR might promote ovarian development by stimulating the expression of SpVgR and SpCyclin B under hEGF-induced treatment. The different physiological response to hEGF in the same vitellogenic stage crabs between summer and winter might be attributed to the changes in metabolism and physiological sensitivity.

Gene expression profiles at different stages for formation of pearl sac and pearl in the pearl oyster Pinctada fucata

Background

The most critical step in the pearl formation during aquaculture is issued to the proliferation and differentiation of outer epithelial cells of mantle graft into pearl sac. This pearl sac secretes various matrix proteins to produce pearls by a complex physiological process which has not been well-understood yet. Here, we aimed to unravel the genes involved in the development of pearl sac and pearl, and the sequential expression patterns of different shell matrix proteins secreted from the pearl sac during pearl formation by pearl oyster Pinctada fucata using high-throughput transcriptome profiling.

Results

Principal component analysis (PCA) showed clearly different gene expression profiles between earlier (before 1 week) and later stages (1 week to 3 months) of grafting. Immune-related genes were highly expressed between 0 h – 24 h (donor dependent) and 48 h – 1 w (host dependent), and in the course of wound healing process pearl sac was developed by two weeks of graft transplantation. Moreover, for the first time, we identified some stem cell marker genes including ABCG2, SOX2, MEF2A, HES1, MET, NRP1, ESR1, STAT6, PAX2, FZD1 and PROM1 that were expressed differentially during the formation of pearl sac. The expression profiling of 192 biomineralization-related genes demonstrated that most of the shell matrix proteins (SMPs) involved in prismatic layer formation were first up-regulated and then gradually down-regulated indicating their involvement in the development of pearl sac and the onset of pearl mineralization. Most of the nacreous layer forming SMPs were up-regulated at 2 weeks after the maturation of pearl sac. Nacrein, MSI7 and shematrin involved in both layer formation were highly expressed during 0 h – 24 h, down-regulated up to 1 week and then up-regulated again after accomplishment of pearl sac formation.

Conclusions

Using an RNA-seq approach we unraveled the expression pattern of the key genes involved in the development of pearl sac and pearl as a result of host immune response after grafting. These findings provide valuable information in understanding the molecular mechanism of pearl formation and immune response in P. fucata.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5579-3) contains supplementary material, which is available to authorized users.

Wound-induced cell proliferation during animal regeneration

Many animal species are capable of replacing missing tissues that are lost upon injury or amputation through the process of regeneration. Although the extent of regeneration is variable across animals, that is, some animals can regenerate any missing cell type whereas some can only regenerate certain organs or tissues, regulated cell proliferation underlies the formation of new tissues in most systems. Notably, many species display an increase in proliferation within hours or days upon wounding. While different cell types proliferate in response to wounding in various animal taxa, comparative molecular data are beginning to point to shared wound-induced mechanisms that regulate cell division during regeneration. Here, we synthesize current insights about early molecular pathways of regeneration from diverse model and emerging systems by considering these species in their evolutionary contexts. Despite the great diversity of mechanisms underlying injury-induced cell proliferation across animals, and sometimes even in the same species, similar pathways for proliferation have been implicated in distantly related species (e.g., small diffusible molecules, signaling from apoptotic cells, growth factor signaling, mTOR and Hippo signaling, and Wnt and Bmp pathways). Studies that explicitly interrogate molecular and cellular regenerative mechanisms in understudied animal phyla will reveal the extent to which early pathways in the process of regeneration are conserved or independently evolved. This article is categorized under: Comparative Development and Evolution > Body Plan Evolution Adult Stem Cells, Tissue Renewal, and Regeneration > Regeneration Comparative Development and Evolution > Model Systems.

Identification of EGFR in pearl oyster (Pinctada fucata martensii) and correlation analysis of its expression and growth traits

Marine pearl production is directly influenced by the growth speed of Pinctada fucata martensii. However, the slow growth rate of this organism remains the main challenge in aquaculture production. Epidermal growth factor receptor (EGFR), an important receptor of tyrosine kinases in animals, plays versatile functions in development, growth and tissue regeneration. In this study, we described the characteristic and function of an EGFR gene identified from P. f. martensii (PmEGFR). PmEGFR possesses a typical EGFR structure and is expressed in all studied tissues, with the highest expression level in adductor muscle. PmEGFR expression level is significantly higher in the fast-growing group than that in the slow-growing one. Correlation analysis represents that shell height and shell weight show positive correlation with PmEGFR expression (p < 0.05), and total weight and tissue weight exhibit positive correlation with it (p < 0.01). This study indicates that PmEGFR is a valuable functional gene associated with growth traits.

The Kinome of Pacific Oyster Crassostrea gigas, Its Expression during Development and in Response to Environmental Factors

Oysters play an important role in estuarine and coastal marine habitats, where the majority of humans live. In these ecosystems, environmental degradation is substantial, and oysters must cope with highly dynamic and stressful environmental constraints during their lives in the intertidal zone. The availability of the genome sequence of the Pacific oyster Crassostrea gigas represents a unique opportunity for a comprehensive assessment of the signal transduction pathways that the species has developed to deal with this unique habitat. We performed an in silico analysis to identify, annotate and classify protein kinases in C. gigas, according to their kinase domain taxonomy classification, and compared with kinome already described in other animal species. The C. gigas kinome consists of 371 protein kinases, making it closely related to the sea urchin kinome, which has 353 protein kinases. The absence of gene redundancy in some groups of the C. gigas kinome may simplify functional studies of protein kinases. Through data mining of transcriptomes in C. gigas, we identified part of the kinome which may be central during development and may play a role in response to various environmental factors. Overall, this work contributes to a better understanding of key sensing pathways that may be central for adaptation to a highly dynamic marine environment.