Identification and Functional Prediction of Large Intergenic Noncoding RNAs (lincRNAs) in Rainbow Trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

Long noncoding RNAs (lncRNAs) have been recognized in recent years as key regulators of diverse cellular processes. Genome-wide large-scale projects have uncovered thousands of lncRNAs in many model organisms. Large intergenic noncoding RNAs (lincRNAs) are lncRNAs that are transcribed from intergenic regions of genomes. To date, no lincRNAs in non-model teleost fish have been reported. In this report, we present the first reference catalog of 9674 rainbow trout lincRNAs based on analysis of RNA-Seq data from 15 tissues. Systematic analysis revealed that lincRNAs in rainbow trout share many characteristics with those in other mammalian species. They are shorter and lower in exon number and expression level compared with protein-coding genes. They show tissue-specific expression pattern and are typically co-expressed with their neighboring genes. Co-expression network analysis suggested that many lincRNAs are associated with immune response, muscle differentiation, and neural development. The study provides an opportunity for future experimental and computational studies to uncover the functions of lincRNAs in rainbow trout.     

Integrative Analysis of Normal Long Intergenic Non-Coding RNAs in Prostate Cancer

Recently, large numbers of normal human tissues have been profiled for non-coding RNAs and more than fourteen thousand long intergenic non-coding RNAs (lincRNAs) are found expressed in normal human tissues. The functional roles of these normal lincRNAs (nlincRNAs) in the regulation of protein coding genes in normal and disease biology are yet to be established. Here, we have profiled two RNA-seq datasets including cancer and matched non-neoplastic tissues from 12 individuals from diverse demography for both coding genes and nlincRNAs. We find 130 nlincRNAs significantly regulated in cancer, with 127 regulated in the same direction in the two datasets. Interestingly, according to Illumina Body Map, significant numbers of these nlincRNAs display baseline null expression in normal prostate tissues but are specific to other tissues such as thyroid, kidney, liver and testis. A number of the regulated nlincRNAs share loci with coding genes, which are either co-regulated or oppositely regulated in all cancer samples studied here. For example, in all cancer samples i) the nlincRNA, TCONS_00029157, and a neighboring tumor suppressor factor, SIK1, are both down regulated; ii) several thyroid-specific nlincRNAs in the neighborhood of the thyroid-specific gene TPO, are both up-regulated; and iii) the TCONS_00010581, an isoform of HEIH, is down-regulated while the neighboring EZH2 gene is up-regulated in cancer. Several nlincRNAs from a prostate cancer associated chromosomal locus, 8q24, are up-regulated in cancer along with other known prostate cancer associated genes including PCAT-1, PVT1, and PCAT-92. We observe that there is significant bias towards up-regulation of nlincRNAs with as high as 118 out of 127 up-regulated in cancer, even though regulation of coding genes is skewed towards down-regulation. Considering that all reported cancer associated lincRNAs (clincRNAs) are biased towards up-regulation, we conclude that this bias may be functionally relevant.     

Computational identification of human long intergenic non-coding RNAs using a GA–SVM algorithm

Long intergenic non-coding RNAs (lincRNAs) are a new type of non-coding RNAs and are closely related with the occurrence and development of diseases. In previous studies, most lincRNAs have been identified through next-generation sequencing. Because lincRNAs exhibit tissue-specific expression, the reproducibility of lincRNA discovery in different studies is very poor. In this study, not including lincRNA expression, we used the sequence, structural and protein-coding potential features as potential features to construct a classifier that can be used to distinguish lincRNAs from non-lincRNAs. The GA–SVM algorithm was performed to extract the optimized feature subset. Compared with several feature subsets, the five-fold cross validation results showed that this optimized feature subset exhibited the best performance for the identification of human lincRNAs. Moreover, the LincRNA Classifier based on Selected Features (linc-SF) was constructed by support vector machine (SVM) based on the optimized feature subset. The performance of this classifier was further evaluated by predicting lincRNAs from two independent lincRNA sets. Because the recognition rates for the two lincRNA sets were 100% and 99.8%, the linc-SF was found to be effective for the prediction of human lincRNAs.     

乏情和发情初产母猪下丘脑–垂体–卵巢轴中lincRNAs表达谱比较分析

初产母猪断奶后能否正常发情对养猪生产影响重大,也是初产母猪被淘汰的主要原因。本研究以乏情和发情初产母猪为研究对象,首次利用RNA-seq技术对其下丘脑-垂体-卵巢轴中的基因间长链非编码RNAs(long intergenic noncoding RNAs,lincRNAs)进行筛选比较,得到lincRNAs的表达图谱,并对其特征和功能进行了初步分析。结果显示,在乏情和发情初产母猪下丘脑–垂体–卵巢轴中鉴定得到3519个lincRNAs,以发情组为对照共有17个lincRNAs存在差异表达,其中12个表达上调,5个表达下调(FC≥2,P<0.05)。选择4个差异表达的lincRNAs经qRT-PCR验证,其表达水平与测序结果基本一致。对这17个差异表达的lincRNAs进行GO分析、KEGG通路分析及lincRNA-mRNA共表达网络分析,发现这些lincRNAs主要与猪卵母细胞减数分裂成熟、卵巢细胞分化及颗粒细胞凋亡等生殖活动相关。本研究结果丰富了猪lincRNAs数据资源,为进一步深入研究初产母猪的生殖机能提供了理论依据。     

Conserved function of lincRNAs in vertebrate embryonic development despite rapid sequence evolution

Thousands of long intervening noncoding RNAs (lincRNAs) have been identified in mammals. To better understand the evolution and functions of these enigmatic RNAs, we used chromatin marks, poly(A)-site mapping and RNA-Seq data to identify more than 550 distinct lincRNAs in zebrafish. Although these shared many characteristics with mammalian lincRNAs, only 29 had detectable sequence similarity with putative mammalian orthologs, typically restricted to a single short region of high conservation. Other lincRNAs had conserved genomic locations without detectable sequence conservation. Antisense reagents targeting conserved regions of two zebrafish lincRNAs caused developmental defects. Reagents targeting splice sites caused the same defects and were rescued by adding either the mature lincRNA or its human or mouse ortholog. Our study provides a roadmap for identification and analysis of lincRNAs in model organisms and shows that lincRNAs play crucial biological roles during embryonic development with functionality conserved despite limited sequence conservation.     

Phosphoproteome profile of human lung cancer cell line A549

As an in vitro model for type II human lung cancer, A549 cells resist cytotoxicity via phosphorylation of proteins as demonstrated by many studies. However, to date, no large-scale phosphoproteome investigation has been conducted on A549. Here, we performed a systematical analysis of the phosphoproteome of A549 by using mass spectrometry (MS)-based strategies. This investigation led to the identification of 337 phosphorylation sites on 181 phosphoproteins. Among them, 67 phosphoproteins and 230 phosphorylation sites identified appeared to be novel with no previous characterization in lung cancer. Based on their known functions as reported in the literature, these phosphoproteins were functionally organized into highly interconnected networks. Western blotting and immunohistochemistry analyses were performed to validate the expression of a bottleneck phosphoprotein YAP1 in cancer cell lines and tissues. This dataset provides a valuable resource for further studies on phosphorylation and lung carcinogenesis.     

Long Intergenic Non-Coding RNAs (LincRNAs) Identified by RNA-Seq in Breast Cancer

In an attempt to find the correlation of aberrant expression of long intergenic noncoding RNAs (lincRNAs) with cancer, twenty-five samples of breast cancer tissue and respective adjacent normal tissue were studied for the expression of lincRNAs by RNA-seq. Among the 538 lincRNAs studied, 124 lincRNAs were exclusively expressed in cancer adjacent tissues and 62 lincRNAs were exclusively expressed in the cancer tissues. Furthermore, the expression of 134 lincRNAs was higher while 272 lower in breast cancer tissue compared with adjacent tissue. The expression of four selected lincRNAs (BC2, BC4, BC5, and BC8) was validated by semi-quantitative and real-time PCR. It was revealed that expression of lincRNA-BC5 was positively correlated with patients'' age, pathological stage, and progesterone receptor concentration, while lincRNA-BC8 was negatively correlated with progesterone receptor expression. Higher expression of lincRNA-BC4 was seen in advanced breast cancer grade. LincRNA-BC2 showed no specific changes in the pathological features studied. Interactions between selected lincRNAs and breast cancer associated proteins were highly suggested by RPIseq based on the specific secondary structure. The results demonstrated that this group of lincRNAs was aberrantly expressed in breast cancer. They might play important roles in the function of oncogenes or tumor suppressors affecting the development and progression of breast cancer.     

Analysis of Eukaryotic lincRNA Sequences Indicates Signatures of Hindered Translation Linked to Selection Pressure

Long intergenic noncoding RNAs (lincRNAs) represent a large fraction of transcribed loci in eukaryotic genomes. Although classified as noncoding, most lincRNAs contain open reading frames (ORFs), and it remains unclear why cytoplasmic lincRNAs are not or very inefficiently translated. Here, we analyzed signatures of hindered translation in lincRNA sequences from five eukaryotes, covering a range of natural selection pressures. In fission yeast and Caenorhabditis elegans, that is, species under strong selection, we detected significantly shorter ORFs, a suboptimal sequence context around start codons for translation initiation, and trinucleotides (“codons”) corresponding to less abundant tRNAs than for neutrally evolving control sequences, likely impeding translation elongation. For human, we detected signatures for cell-type-specific hindrance of lincRNA translation, in particular codons in abundant cytoplasmic lincRNAs corresponding to lower expressed tRNAs than control codons, in three out of five human cell lines. We verified that varying tRNA expression levels between cell lines are reflected in the amount of ribosomes bound to cytoplasmic lincRNAs in each cell line. We further propose that codons at ORF starts are particularly important for reducing ribosome-binding to cytoplasmic lincRNA ORFs. Altogether, our analyses indicate that in species under stronger selection lincRNAs evolved sequence features generally hindering translation and support cell-type-specific hindrance of translation efficiency in human lincRNAs. The sequence signatures we have identified may improve predicting peptide-coding and genuine noncoding lincRNAs in a cell type.     

The Function of SARI in Modulating Epithelial-Mesenchymal Transition and Lung Adenocarcinoma Metastasis

The SARI (suppressor of AP-1, regulated by IFN) gene, which is also called BATF2, is associated with the risk of several kinds of cancer, and loss of SARI expression is frequently detected in aggressive and metastatic cancer. However, the functional role of SARI in lung adenocarcinoma remains unknown. We have shown that loss of SARI expression initiates epithelial-mesenchymal transition (EMT), which is visualized by repression of E-cadherin and up-regulation of vimentin in lung adenocarcinoma cell lines and in clinical lung adenocarcinoma specimens. Using a human lung xenograft-mouse model, we observed that knocking down endogenous SARI in human carcinoma cells leads to the development of multiple lymph node metastases. Moreover, we showed that SARI functions as a critical protein in regulating EMT by modulating the (GSK)-3β-β-catenin signaling pathway. These results demonstrate the mechanism of SARI function in EMT and suggest that assessment of SARI may serve as a prognostic biomarker and potential therapeutic target for lung adenocarcinoma metastasis.