Expression and Regulation Profile of Mature MicroRNA in the Pig: Relevance to Xenotransplantation

Droplet Digital PCR Quantification of Selected Intracellular and Extracellular microRNAs Reveals Changes in Their Expression Pattern during Porcine In Vitro Adipogenesis

Extracellular miRNAs have attracted considerable interest because of their role in intercellular communication, as well as because of their potential use as diagnostic and prognostic biomarkers for many diseases. It has been shown that miRNAs secreted by adipose tissue can contribute to the pathophysiology of obesity. Detailed knowledge of the expression of intracellular and extracellular microRNAs in adipocytes is thus urgently required. The system of in vitro differentiation of mesenchymal stem cells (MSCs) into adipocytes offers a good model for such an analysis. The aim of this study was to quantify eight intracellular and extracellular miRNAs (miR-21a, miR-26b, miR-30a, miR-92a, miR-146a, miR-148a, miR-199, and miR-383a) during porcine in vitro adipogenesis using droplet digital PCR (ddPCR), a highly sensitive method. It was found that only some miRNAs associated with the inflammatory process (miR-21a, miR-92a) were highly expressed in differentiated adipocytes and were also secreted by cells. All miRNAs associated with adipocyte differentiation were highly abundant in both the studied cells and in the cell culture medium. Those miRNAs showed a characteristic expression profile with upregulation during differentiation.

New long-non coding RNAs related to fat deposition based on pig model

Obesity is a problem in the last decades since the development of certain technologies has forced submission to a faster pace of life, resulting in nutritional changes. Domestic pigs are an excellent animal model in recognition of adiposity-related processes, corresponding to the size of individual organs, the distribution of body fat in the organism, and similar metabolism. The present study applied next-generation sequencing to identify adipose tissue (AT) transcriptomic signals related to increased fat content by identifying differentially expressed genes (DEGs), including long-non coding RNAs in Złotnicka White pigs (n=16). Moreover, besides commonly used functional analysis, we applied the Freiburg RNA tool to predict DE lncRNA targets based on calculation hybridisation energy. And in addition, DE lncRNAs were recognized based on information available in databases. The obtained results show that closely 230 gene expression was found to be dependent on fat content, included 8 lncRNAs. The most interesting was that among identified DE lncRNAs was transcript corresponding to human MALAT1, which was previously considered in the obesity-related context. Moreover, it was identified that in ENSSSCG00000048394, ENSSSCG00000047210, ENSSSCG00000047442 and ENSSSCG00000041577 lncRNAs are contained repeat insertion domains of LncRNAs (RIDLs) considered as important gene expression regulatory elements, and ENSSSCG00000041577 seems to be the host for mir1247(NR_031649.1). The analysis of energy hybridisation between DE lncRNAs and DEGs using the Freiburg IntaRNAv2 tool, including isoforms expressed in AT, showed that ENSSSCG00000047210 lncRNA interacted with the highest number of DEGs and ENSSSCG00000047210 expression was only correlated with positive fat-related DEGs. The functional analysis showed that down-regulated DEGs involved in ECM proteoglycan pathways could be under control of both positive and negative fat-related lncRNAs. The present study, using pigs as an animal model, expands our current knowledge of possible gene expression regulation by lncRNAs in fat tissue and indicates for MALAT1 role in the fat deposition determination, which function is still often questioned or doubtful.

Genetically engineered animal models for Marfan syndrome: challenges associated with the generation of pig models for diseases caused by haploinsufficiency

Recent developments in reproductive biology have enabled the generation of genetically engineered pigs as models for inherited human diseases. Although a variety of such models for monogenic diseases are currently available, reproduction of human diseases caused by haploinsufficiency remains a major challenge. The present study compares the phenotypes of mouse and pig models of Marfan syndrome (MFS), with a special focus on the expressivity and penetrance of associated symptoms. Furthermore, investigation of the gene regulation mechanisms associated with haploinsufficiency will be of immense utility in developing faithful MFS pig models.

Expression analysis of porcine miR-33a/b in liver, adipose tissue and muscle and its potential role in fatty acid metabolism

mir-33a and mir-33b are co-transcribed with the SREBF2 and SREBF1 transcription factors, respectively. The main role of SREBF1 is the regulation of genes involved in fatty acid metabolism, while SREBF2 regulates genes participating in cholesterol biosynthesis and uptake. Our objective was to study the expression of both miR-33a and miR-33b, together with their host SREBF genes, in liver, adipose tissue and muscle to better understand the role of miR-33a/b in the lipid metabolism of pigs. In our study, the expression of miR-33a, miR-33b and SREBF2 in liver, adipose tissue, and muscle was studied in 42 BC1_LD (25% Iberian x 75% Landrace backcross) pigs by RT-qPCR. In addition, the expression of in-silico predicted target genes and fatty acid composition traits were correlated with the miR-33a/b expression. We observed different tissue expression patterns for both miRNAs. In adipose tissue and muscle a high correlation between miR-33a and miR-33b expression was found, whereas a lower correlation was observed in liver. The expression analysis of in-silico predicted target-lipid related genes showed negative correlations between miR-33b and CPT1A expression in liver. Conversely, positive correlations between miR-33a and PPARGC1A and USF1 gene expression in liver were observed. Lastly, positive and negative correlations between miR-33a/b expression and saturated fatty acid (SFA) and polyunsaturated fatty acid (PUFA) content, respectively, were identified. Overall, our results suggested that both miRNAs are differentially regulated and have distinct functions in liver, in contrast to muscle and adipose tissue. Furthermore, the correlations between miR-33a/b expression both with the expression of in-silico predicted target-lipid related genes and with fatty acid composition, opens new avenues to explore the role of miR33a/b in the regulation of lipid metabolism.

Integrated analysis of miRNA-mRNA interaction in ovaries of Turpan Black Sheep during follicular and luteal phases

To investigate the regulatory mechanism of the follicular-luteal phase transition in Turpan black sheep (Ovis aries), the genome-wide expression patterns of microRNAs (miRNAs) and genes were investigated in ovaries of six sheep (3 years and single lamb with 3 consecutive births) during follicular and luteal phases of the oestrous cycle. Bioinformatic analysis was used to screen potential miRNAs and genes related to Turpan black sheep ovarian function. RT-qPCR was used to validate the sequencing results. In total, we identified 139 known and 71 novel miRNAs in the two phases with miRNA-seq, and a total of 19 miRNAs were significantly differentially expressed, of which 7 were up-regulated and 12 were down-regulated in the follicular phase compared with luteal phase. A total of 150 genes were significantly differentially expressed, including 63 up-regulated and 87 down-regulated in the follicular phase compared with the luteal phase by RNA-seq data analysis. Those DEGs were significantly enriched in 103 GO terms and several KEGG pathways, including metabolic pathway, ovarian steroidogenesis, steroid hormone biosynthesis and oestrogen signalling pathway. In addition, we created a miRNA-mRNA regulatory network to further elucidate the mechanism of follicular-luteal transition. Finally, we identified key miRNAs and genes including miR-143, miR-99a, miR-150, miR-27a, miR-125b, STAR, STAT1, which might play crucial roles in reproductive hormone biosynthesis and follicular development. The miRNA-mRNA interactive network clearly illustrates molecular basis involving in follicular-luteal transition.

The potential role of 3D-bioprinting in xenotransplantation

PURPOSE OF REVIEW

To review the impact of a new technology, 3D-bioprinting, in xenotransplantation research.

RECENT FINDINGS

Genetically engineered pigs, beginning with human (h) CD55-transgenic and Gal-knockout pigs, have improved the outcomes of xenotransplantation research. Today, there are more than 30 different genetically engineered pigs either expressing human gene(s) or lacking pig gene(s). CRIPSR/cas9 technology has facilitated the production of multigene pigs (up to nine genes in a single pig), which lack multiple pig xenoantigens, and express human transgenes, such as hCD46, hCD55, hThrombomodulin, hCD39, etc. Although recent studies in nonhuman primates (NHPs) have demonstrated prolonged survival after life-supporting pig kidney, heart, and islet xenotransplantation, researchers have difficulty determining the best genetic combination to test in NHPs because of a potential greater than 100 000 genetic combinations. 3D-bioprinting of genetically engineered pig cells: is superior to 2D in-vitro testing, enables organ-specific testing, helps to understand differences in immunogenicity between organs, and is faster and cheaper than testing in NHPs. Moreover, 3D-bioprinted cells can be continuously perfused in a bioreactor, controlling for all variables, except the studied variable.

SUMMARY

3D-bioprinting can help in the study of the impact of specific genes (human or pig) in xenotransplantation in a rapid, inexpensive, and reliable way.

Lipid Deposition and Metabolism in Local and Modern Pig Breeds: A Review

Modern pig breeds, which have been genetically improved to achieve fast growth and a lean meat deposition, differ from local pig breeds with respect to fat deposition, fat specific metabolic characteristics and various other properties. The present review aimed to elucidate the mechanisms underlying the differences between fatty local and modern lean pig breeds in adipose tissue deposition and lipid metabolism, taking into consideration morphological, cellular, biochemical, transcriptomic and proteomic perspectives. Compared to modern breeds, local pig breeds accumulate larger amounts of fat, which generally contains more monounsaturated and saturated fatty acids; they exhibit a higher adipocyte size and higher activity of lipogenic enzymes. Studies using transcriptomic and proteomic approaches highlighted several processes like immune response, fatty-acid turn-over, oxidoreductase activity, mitochondrial function, etc. which differ between local and modern pig breeds.

Introduction: The Present Status of Xenotransplantation Research

There is a well-known worldwide shortage of deceased human donor organs for clinical transplantation. The transplantation of organs from genetically engineered pigs may prove an alternative solution. In the past 5 years, there have been sequential advances that have significantly increased pig graft survival in nonhuman primates. This progress has been associated with (1) the availability of increasingly sophisticated genetically engineered pigs; (2) the introduction of novel immunosuppressive agents, particularly those that block the second T-cell signal (costimulation blockade); (3) a better understanding of the inflammatory response to pig xenografts; and (4) increasing experience in the management of nonhuman primates with pig organ or cell grafts. The range of investigations required in experimental studies has increased. The standard immunologic assays are still carried out, but increasingly investigations aimed toward other pathobiologic barriers (e.g., coagulation dysregulation and inflammation) have become more important in determining injury to the graft.Now that prolonged graft survival, extending to months or even years, is increasingly being obtained, the function of the grafts can be more reliably assessed. If the source pigs are bred and housed under biosecure isolation conditions, and weaned early from the sow, most microorganisms can be eradicated from the herd. The potential risk of porcine endogenous retrovirus (PERV) infection remains unknown, but is probably small. Attention is being directed toward the selection of patients for the first clinical trials of xenotransplantation.

Spatial Transcriptomic and miRNA Analyses Revealed Genes Involved in the Mesometrial-Biased Implantation in Pigs

Implantation failure is a major cause of early embryonic loss. Normally, the conceptus attachment is initiated at mesometrial side of the uterus and then spread to the anti-mesometrial side in pigs, however, the mechanisms that direct the mesometrial-biased attachment are largely unknown. In this study, the histological features of the entire uterine cross-section from gestational days 12 (pre-attachment stage) and 15 (post-attachment stage) were investigated and the differences in histological features between the mesometrial and anti-mesometrial side of the uterus were observed. Then, transcriptomic and miRNA analyses were performed on mesometrial and anti-mesometrial endometrium obtained from gestational days 12 and 15, respectively. Differentially expressed genes (DEGs) and miRNAs (DE-miRs) that were common to both or unique to either of the two anatomical locations of uterus were identified, respectively, indicating that differences in molecular response to the implanting conceptus exist between the two anatomical locations. In addition, we detected DEGs and DE-miRs between the two anatomical locations on the two gestational days, respectively. Of these DEGs, a number of genes, such as chemokine and T cell surface marker genes, were found to be significantly up-regulated mesometrially. Furthermore, we detected the interaction of CXCR4, CXCL11 and miR-9 using dual luciferase reporter assay. Taken together, this study revealed genes and pathways that might play the role of creating a receptive microenvironment at the mesometrial side, which is required to guide a proper positioning of conceptus in the uterus in pigs.

miR‑9 depletion suppresses the proliferation of osteosarcoma cells by targeting p16

Osteosarcoma (OS) is a common primary malignancy in adolescents and children. MicroRNAs (miRNAs or miRs) can regulate the progression of OS. Herein, we explored the target genes and effects of miR-9 in OS. Cell growth, colony formation and cell cycle were respectively examined using a cell counting kit-8 (CCK-8), crystal violet staining and flow cytometry. The target gene of miR-9 was predicted according to the MicroRNA.org website. Luciferase activity was examined using a dual luciferase reporter gene assay kit. The corresponding factors levels were analyzed by carrying out reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis. A mouse model of OS was also established and the volume and weight of the tumors of the mice with OS were measured. The levels of p16 in the mice with OS were detected by immunohistochemistry (IHC). The data revealed a high expression of miR-9 and a low expression of p16 in the OS tissue. p16 was found to be the target gene for miR-9 in OS. miR-9 depletion decreased the proliferation and colony formation of Saos-2 cells by arresting the cells at the G1 phase, accompanied by the downregulation of cyclin A, cyclin D1 and c-Myc expression levels. Moreover, miR-9 depletion inhibited the phosphorylation of p38, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). In vivo, miR-9 depletion decreased the tumor volume and weight and increased p16 expression in the mouse tumor tissues. Nevertheless, p16 silencing reversed the suppressive effects of miR-9 inhibitors on OS cells. On the whole, the findings of this study substantiate that miR-9 depletion suppresses cell proliferation by targeting p16 in OS and by mediating the activation of the ERK/p38/JNK pathway.