The characterization of RHEB gene and its responses to hypoxia and thermal stresses in the small abalone Haliotis diversicolor

New Association Between Diabetes Mellitus and Pancreatic Cancer

BACKGROUND

Diabetes mellitus is a global issue that has affected the lives of many people all over the world. This disorder, which is also called the mother of all diseases, possesses high pathogenicity and results in the emergence of many disorders. One of the known correlated diseases is pancreatic cancer which can be accompanied by diabetes mellitus. Therefore, finding the association between these diseases and common genes is urgent.

OBJECTIVE

In this study, in order to survey the relationship between diabetes mellitus and pancreatic cancer, the common genes of these disorders were analyzed by bioinformatics tools.

METHODS

For this purpose, we screened 17 shared genes from microarray data downloaded from the Gene Expression Omnibus (GEO) database. In addition, the relationship between identified genes was constructed by STRING and DAVID tools.

RESULTS

In total, 112 genes were identified to be differentially expressed. Among these, 17 genes were found to be common, including two genes that were down-regulated and others that were upregulated. Other analyses showed that most of the genes were enriched in Vibrio cholera infection and the mTOR signaling pathway. The biological processes of such genes included oxygen and gas transport, phagosome acidification, and GTPase activity.

CONCLUSION

In this study, 17 common genes that had not previously been considered in diabetes and pancreatic cancer were screened, which can be further considered for clinical approaches and in vitro studies.

Transcriptomic responses to thermal stress in hybrid abalone (Haliotis discus hannai ♀ × H. fulgens ♂)

China is the world’s largest abalone producing country. Currently, summer mortality caused by high temperature, is one of the biggest challenges for abalone aquaculture industry. The hybrid abalone (Haliotis discus hannai ♀ × H. fulgens ♂) was conferred on the “new variety”. It has heterosis for thermal tolerance and has been cultured at large-scale in southern China. In this study, a transcriptome analysis was performed to identify the related genes in this hybrid abalone under thermal stress and recovery stage. Compared to control group (18°C), a total of 75, 2173, 1050, 1349, 2548, 494, and 305 differentially expressed genes (DEGs) were identified at 21°C, 24°C, 27°C, 30°C, 32°C, 29°C, and 26°C, respectively. In this study, 24°C is the critical temperature at which the abalone is subjected to thermal stress. With the temperature rising, the number of stress-responsive genes increased. During the temperature recovering to the optimum, the number of stress-responsive genes decreased gradually. Thus, this hybrid abalone has a rapid response and strong adaptability to the temperature. Under the thermal stress, the abalone triggered a complicated regulatory network including degrading the misfolded proteins, activating immune systems, negative regulation of DNA replication, and activating energy production processes. The more quickly feedback regulation, more abundant energy supply and more powerful immune system might be the underlying mechanisms to fight against thermal stress in this hybrid abalone. These findings could provide clues for exploring the thermal-response mechanisms in abalone. The key genes and pathways would facilitate biomarker identification and thermal-tolerant abalone breeding studies.

Comparative transcriptomics of high-altitude Vulpes and their low-altitude relatives

The harsh environment of Qinghai-Tibet Plateau (QTP) imposes strong selective stresses (e.g., hypoxia, high UV-radiation, and extreme temperature) to the native species, which have driven striking phenotypic and genetic adaptations. Although the mechanisms of high-altitude adaptation have been explored for many plateau species, how the phylogenetic background contributes to genetic adaption to high-altitude of Vulpes is largely unknown. In this study, we sequenced transcriptomic data across multiple tissues of two high-altitude Vulpes (Vulpes vulpes montana and Vulpes ferrilata) and their low-altitude relatives (Vulpes corsac and Vulpes lagopus) to search the genetic and gene expression changes caused by high-altitude environment. The results indicated that the positive selection genes (PSGs) identified by both high-altitude Vulpes are related to angiogenesis, suggesting that angiogenesis may be the result of convergent evolution of Vulpes in the face of hypoxic selection pressure. In addition, more PSGs were detected in V. ferrilata than in V. v. montana, which may be related to the longer adaptation time of V. ferrilata to plateau environment and thus more genetic changes. Besides, more PSGs associated with high-altitude adaptation were identified in V. ferrilata compared with V. v. montana, indicating that the longer the adaptation time to the high-altitude environment, the more genetic alterations of the species. Furthermore, the result of expression profiles revealed a tissue-specific pattern between Vulpes. We also observed that differential expressed genes in the high-altitude group exhibited species-specific expression patterns, revealed a convergent expression pattern of Vulpes in high-altitude environment. In general, our research provides a valuable transcriptomic resource for further studies, and expands our understanding of high-altitude adaptation within a phylogenetic context.

Time course analysis of immunity-related gene expression in the sea cucumber Apostichopus japonicus during exposure to thermal and hypoxic stress

Temperature and dissolved oxygen concentration are important abiotic factors that can limit the growth and survival of sea cucumbers by affecting their immune systems. As global warming intensifies, sea cucumbers are increasingly exposed to adverse environmental conditions, which can cause severe economic losses and limit the sustainable development of sea cucumber aquaculture. It is therefore important to better understand how sea cucumbers respond to environmental stress, especially with regard to its effects on immunity. In the present study, the time series of immunity-related gene expression in sea cucumbers under thermal and hypoxic stresses were analyzed separately. The expression trends of 17 genes related to the nuclear factor κB (NF-κB) pathway, the protease family, the complement system, heat shock proteins (HSPs) and the transferrin family during exposure to two stresses at eight time points were concluded. These genes have interconnected roles in stress defense. The expression levels of genes relating to the NF-κB pathways and HSPs were strongly affected in the sea cucumber thermal stress response, while melanotransferrin (Mtf), ferritin (Ft) and mannan-binding C-type lectin (MBCL) were affected by hypoxia. In contrast, complement factor B (Bf), myosin V (Mys) and serine protease inhibitor (SPI) were not that sensitive during the initial period of environmental stress. Similar expression patterns under both thermal and hypoxic stress for certain genes, including an increase in Hsp90 and decreases in lysozyme (Lys), major yolk protein (MYP) and cathepsin C (CTLC) were observed in sea cucumbers. Conversely, NF-κB and Hsp70 were differentially affected by the two stress treatments. Lysozyme-induced immune defense was inconstant in sea cucumbers coping with stress. A gene ontology (GO) analysis of the selected genes revealed that the most co-involved terms related to immunity and iron ion. Our analysis suggests that sea cucumbers demonstrate complex and varied immune responses to different types of stresses. This dynamic image of the immune responses and stress tolerance of sea cucumbers provides new insights into the adaptive strategies of holothurians in adverse environments.

MicroRNA-194 overexpression protects against hypoxia/reperfusion-induced HK-2 cell injury through direct targeting Rheb

Renal ischemia-reperfusion injury, a major cause of renal failure, always leads to acute kidney injury and kidney fibrosis. MicroRNAs (miRs) have been reported to be associated with renal ischemia-reperfusion injury. miR-194 was downregulated following renal ischemia-reperfusion injury; however, the function and mechanism of miR-194 in renal ischemia-reperfusion injury have not yet been fully understood. In the present study, we constructed renal ischemia-reperfusion injury model in vitro through treatment of human kidney proximal tubular epithelial cells HK-2 by hypoxia/reperfusion (H/R). We observed that miR-194 was decreased in H/R-induced HK-2 cells. miR-194 mimic increased H/R-induced HK-2 cell survival, whereas miR-194 inhibitor further strengthened H/R- inhibited HK-2 cell survival. Also, we observed that miR-194 overexpression suppressed oxidative stress markers, including malondialdehyde, glutathione, and secretion of pro-inflammatory cytokines, including IL-6, IL-1β, and TNF-α; however, miR-194 inhibitor showed the reverse effects. Results from dual-luciferase analysis confirmed that Ras homology enriched in brain (Rheb) was a direct target of miR-194. Finally, we corroborated that miR-194 affected cell growth, oxidative stress, and inflammation through targeting Rheb in H/R-induced HK-2 cells. In conclusion, our results suggested that miR-194 protect against H/R-induced injury in HK-2 cells through direct targeting Rheb.

Integrative transcriptome analysis and discovery of genes involving in immune response of hypoxia/thermal challenges in the small abalone Haliotis diversicolor

In recent years, the abalone aquaculture industry has been threatened by the deteriorating environmental conditions, such as hypoxia and thermal stress in the hot summers. It is necessary to investigate the molecular mechanism in response to these environmental challenges, and subsequently understand the immune defense system. In this study, the transcriptome profiles by RNA-seq of hemocytes from the small abalone Haliotis diversicolor after exposure to hypoxia, thermal stress, and hypoxia plus thermal stress were established. A total of 103,703,074 clean reads were obtained and 99,774 unigenes were assembled. Of the 99,774 unigenes, 47,154 and 20,455 had homologous sequences in the Nr and Swiss-Prot protein databases, while 16,944 and 10,840 unigenes could be classified by COG or KEGG databases, respectively. RNAseq analysis revealed that the differentially expressed genes (DEGs) after challenges of hypoxia, thermal stress, or hypoxia plus thermal stress were 24,189, 29,165 and 23,665, among which more than 3000 genes involved in at least 230 pathways, including several classical immune-related pathways. The genes and pathways that were involved in immune response to hypoxia/thermal challenges were identified by transcriptome analysis and further validated by quantitative real-time PCR and RNAi technology. The findings in this study can provide information on H. diversicolor innate immunity to improve the abalone aquaculture industry, and the analysis of the potential immune-related genes in innate immunity signaling pathways and the obtained transcriptome data can provide an invaluable genetic resource for the study of the genome and functional genes.