| The innate immune system is composed of a variety of cells. These cells can form a rapid immune response and protect the body against pathogens. Natural killer cells (NK cells) are a kind of cytotoxic innate immune cells which play essential roles in protecting body from pathogen and tumor cells. NK cells can release perforin and granzyme, and furthermore, NK cells can bind target cells through Fas-L and Fas interaction to induce target cells apoptosis. Activated NK cells can also produce pro-inflammatory cytokines such as IFNy to further promote innate and adaptive immune response. It has been more than 40 years since the conventional NK were discovered. There also have been a lot of researches concerning NK cells development and function. Recent studies have found and identified a variety of innate lymphocytes including different kinds of tissue-resident NK cells. And the memory potential of NK cells has also been found, which indicated that the innate immune system might also possess the characteristics of adaptive immune cells.The "RNA world hypothesis" considers RNA as the basis of early life. RNA then transferred genetic information to DNA which is more stable and catalytic function to proteins which are more diverse. Although RNA plays important roles in early translation and splicing, most opinions take RNA for the intermediate of genes and proteins, named the central dogma "DNA makes RNA makes protein". However, researchers found that most complex organism genomes are transcribed into RNA, and discovered a new type of regulatory non-coding RNA, ncRNAs. Although most studies have focused on the short RNAs, a growing number of researches have found this kind of long transcripts, which do not code proteins but can function in the form of RNA. Although there is not a clear classification for these transcripts, long non-coding RNAs are thought to be a class of RNAs that are longer than 200 nucleotides.In our research, we isolated and purified human early pregnancy decidual NK (dNK), peripheral blood NK (pNK), umbilical cord blood NK (cNK) and peripheral blood T cells. T cells were used as control. We performed lncRNA microarray on these four kinds of cells. The following progresses have been made:1, we analyzed high expressed lncRNAs in these four cells respectively and found that they have their own different lncRNAs expression profiles. This is consistent with the previous opinion that the expression of lncRNAs is more cell-specific than proteins. These differentially expressed lncRNAs may play important roles in cell development and function.2, we analyzed three kinds of NK cells described above. We analyzed their lncRNAs cross expressed and their lncRNAs expression correlation. We found the correlation of lncRNAs expression between human peripheral blood NK cells and cord blood NK cells is relatively high and their correlation with decidual NK cells is relatively low. This is also consistent with the previous idea and the previous research of our lab, which suggest human pNK and cNK are more mature NK cells with higher cytotoxicity compared to dNK cells.3, we performed the gene clustering analysis on target genes of lncRNAs because target genes may reflect the lncRNA function. According to the main function of natural killer cells, we divided target genes predicted into three categories: differentiation, cytotoxicity and cytokine secretion. We found lncRNAs which may regulate these genes involved in these biology processes express differentially in pNK and cNK compared to dNK. This also provides another mechanism that these lncRNAs differentially expressd may regulate the expression of target genes, resulting in different function of different subsets of NK cells.4, one lncRNA which is expressed high in dNK cells was analyzed. This lncRNA is higher expressed in dNK cells compared to pNK and cNK cells, but almost not expressed in peripheral T cell. Because its location in the genome is within the first intron of CD56, a characteristic surface marker of NK cells, we named it lnc-CD56. We found after knockdown of this lncRNA, the expression of CD56 is also down-regulated, showing that it can regulate the expression of CD56.In conclusion, the innovation of our research is performing lncRNA microarray assay of human NK cells for the first time and systematic bioinformatics analysis of microarray data. And according to the gene clustering, we found a series of lncRNAs may function in NK cells differentiation, cytotoxicity or cytokine secretion, providing a series of available data for the future study of NK cells. And we also found a lncRNA can regulate a NK cell surface molecule CD56 which can be used to distinguish NK cells, so we named it lnc-CD56. Our research showed it could regulate the expression of CD56 positively and might promote NK cell lineage development. This may provide a quicker method to gain more NK cells when conduct in vitro NK cells induction. |
PDF Full Text Request