N4-acetylcytidine of Nop2 mRNA is required for the transition of morula-to-blastocyst.

N-acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac4C) modification is crucial for mRNA stability and translation efficiency, yet the underlying function in mammalian preimplantation embryos remains unclear. Here, we characterized the ac4C modification landscape in mouse early embryos and found that the majority of embryos deficient in ac4C writer-NAT10 failed to develop into normal blastocysts. Through single-cell sequencing, RNA-seq, acetylated RNA immunoprecipitation combined with PCR (acRIP-PCR), and embryonic phenotype monitoring, Nop2 was screened as a target gene of Nat10. Mechanistically, Nat10 knockdown decreases the ac4C modification on Nop2 mRNA and reduces RNA and protein abundance by affecting the mRNA stability of Nop2. Then, depletion of NOP2 may inhibit the translation of transcription factor TEAD4, resulting in defective expression of the downstream lineage-specific gene Cdx2, and ultimately preventing blastomeres from undergoing the trophectoderm (TE) fate. However, exogenous Nop2 mRNA partially reverses this abnormal development. In conclusion, our findings demonstrate that defective ac4C modification of Nop2 mRNA hinders the morula-to-blastocyst transition by influencing the first cell fate decision in mice.

Epigenetic silencing of ASPP1 confers 5-FU resistance in clear cell renal cell carcinoma by preventing p53 activation.

Inactivation of p53 has been shown to correlate with drug resistance in tumors. However, in clear cell renal cell carcinoma (ccRCC), p53 is rarely mutated, yet the tumors remain highly insensitive to the conventional chemotherapeutic drugs. The underlying mechanisms responsible for the non-genetic p53 inactivation remain obscure. Here, we report, for the first time, that Apoptosis Stimulating of P53 Protein 1 (ASPP1) was remarkably downregulated at both mRNA (about 3.9-fold) and protein (about 4.9-fold) levels in ccRCC human specimens in comparison with the paired normal controls. In addition, lower ASPP1 was closely related to the higher grade of tumors and shorter life expectancy of ccRCC patients, both with p < 0.001. We also find that CpG island hypermethylation at promoter region contributed to the suppression of ASPP1 expression in ccRCC that contained relatively low levels of ASPP1. Further functional studies demonstrated that forced expression ASPP1 not only significantly inhibited the growth rate of ccRCC, but also promoted sensitivity of ccRCC to the conventional chemotherapeutic drug 5-fluorouracil (5-FU)-induced apoptosis. Moreover, ASPP1 expression was accompanied with the apoptosis-prone alterations of p53 targets expression and p53 target PIG3 luciferase reporter activation. In contrast, ASPP1 knockdown promoted cell growth and prevent 5-FU-induced p53 activation and apoptosis. In conclusion, our results suggest that ASPP1 silencing is one of dominate mechanisms in inhibiting wild type p53 in ccRCC. ASPP1, therefore, may be potentially used as a promising biomarker for prognosis and therapeutic intervention in ccRCC.

Nop2 is required for mammalian preimplantation development.

Nucleolar protein 2 (NOP2) is evolutionarily conserved from yeast to human, and has been found to play an important role in accelerating cell proliferation, cell-cycle progression, and tumor aggressiveness. The expression pattern and function of Nop2 during early mammalian embryo development, however, has not been investigated. We identified Nop2 as an essential gene for development to the blastocyst stage while performing an RNA interference (RNAi)-based screen in mouse preimplantation embryos. Nop2 is expressed throughout preimplantation development, with highest mRNA and protein accumulation at the 8-cell and morula stages, respectively. RNAi-mediated knockdown of Nop2 results in embryos that arrest as morula. NOP2-deficient embryos exhibit reduced blastomere numbers, greatly increased apoptosis, and impaired cell-lineage specification. Furthermore, knockdown of Nop2 results in global reduction of all RNA species, including rRNA, small nuclear RNA, small nucleolar RNA, and mRNA. Taken together, our results demonstrate that Nop2 is an essential gene for blastocyst formation, and is required for RNA processing and/or stability in vivo during preimplantation embryo development in the mouse.

Expression patterns of long noncoding RNAs from Dlk1-Dio3 imprinted region and the potential mechanisms of Gtl2 activation during blastocyst development.

The function of long noncoding RNAs (lncRNAs) in cell differentiation and development have begun to be revealed in recent years. However, the expression pattern and mechanisms regulating lncRNAs are largely unknown during mammalian preimplantation development. LncRNAs expressed from Dlk1-Dio3 imprinted region have been linked to pluripotency of induced pluripotent cells (iPSCs). In this study we show that these lncRNAs (Gtl2, Rian and Mirg) are first expressed at the morula stage and gradually restricted to the inner cell mass (ICM) as the embryo differentiates into the blastocyst. Analysis of DNA methylation at IG-DMR and Gtl2-DMR showed no change during preimplantation while the presence of the activating histone modification H3K4me3 increased significantly from 8-cell to blastocyst stage, which may explain the expression activation. Additionally, knockdown of transcription factors (Oct4, Sox2 and Nanog) in blastocyst reduced the expression of Gtl2, indicating pluripotency factors regulate transcription of these lncRNAs. This study provides the spatiotemporal expression and dynamic changes of lncRNAs from Dlk1-Dio3 imprinted region in mouse preimplantation stage embryos and offers insight into the potential mechanisms responsible for Gtl2 activation.

Identification of 4438 novel lincRNAs involved in mouse pre-implantation embryonic development.

Long intergenic non-coding RNAs (lincRNAs) as a key group of non-coding RNAs have gained substantial attention. Though lincRNAs have been systematically explored in various mouse tissues and cell lines, large-scale identification of lincRNAs in mouse pre-implantation embryonic development (PED) process has not be documented previously. Therefore, it is important to identify and characterize novel lincRNAs that may be involved in PED. In this paper, we performed transcriptome assembly based on published single-cell RNA-seq data during mouse PED and identified 4,438 putative lincRNAs. Combining these with Ensembl lincRNAs, we established a reference catalog of 5,808 transcribed lincRNAs in PED. We then systematically analyzed the lincRNAs in this reference catalog and revealed that the identified novel PED lincRNAs are generally comparable with known Ensembl lincRNAs in genomic aspects. In addition, the global expression patterns can be separated by zygote first cleavage division in clustering analysis and we further identified and analyzed differentially expressed lincRNAs involved in this process. The expression of lincRNAs involved in the process is negatively correlated with promoter methylation in trend. The identified lincRNAs involved in zygote first cleavage division could have important roles in mouse early embryonic development and need further functional studies. Altogether, a novel reference catalog of mouse PED lincRNAs is provided and characterized, which would be a valuable resource for further functional analyses and may help elucidate the pre-implantation regulatory mechanism.

The intramolecular SN2 reaction tautomeric ent-Kauranoids isolated from the aerial parts of Isodon amethystoides.

As our ongoing searching for the bioactive natural terpenoids, nine ent-kauranoids (1-9), including three previously undescribed ones (1, 2, and 9), were isolated from the aerial parts of Isodon amethystoides. Their structures were elucidated on the basis of spectroscopic data analysis, including NMR, MS, and ECD. Compounds 1 and 2 were a pair of tautomeric compounds, which was confirmed by the HPLC analysis and low temperature NMR testing. The underlying mechanism of the tautomer was proposed as an intramolecular SN2 reaction, which was explained by quantum chemical calculation. The HOMO-LUMO gap and the free energy revealed the spontaneous of the tautomeric of the 1 and 2. Additionally, the similar phenomena were also found in the two groups of known compounds 3 and 4 and 6 and 7, respectively. Apart from the tautomer, compounds 3 and 4 can be hydrolyzed into 5 through ester hydrolysis in CDCl3, while compounds 6, 7 can be hydrolyzed into 8 through ester hydrolysis. These phenomena were also confirmed through HPLC analysis and low temperature nuclear magnetic resonance tests and the mechanism was studied using quantum chemical calculation.

Identification of oleic acid as an endogenous ligand of GPR3.

Although GPR3 plays pivotal roles in both the nervous system and metabolic processes, such as cold-induced thermogenesis, its endogenous ligand remains elusive. Here, by combining structural approach (including cryo-electron microscopy), mass spectrometry analysis, and functional studies, we identify oleic acid (OA) as an endogenous ligand of GPR3. Our study reveals a hydrophobic tunnel within GPR3 that connects the extracellular side of the receptor to the middle of plasma membrane, enabling fatty acids to readily engage the receptor. Functional studies demonstrate that OA triggers downstream Gs signaling, whereas lysophospholipids fail to activate the receptor. Moreover, our research reveals that cold stimulation induces the secretion of OA in mice, subsequently activating Gs/cAMP/PKA signaling in brown adipose tissue. Notably, brown adipose tissues from Gpr3 knockout mice do not respond to OA during cold stimulation, reinforcing the significance of GPR3 in this process. Finally, we propose a "born to be activated and cold to enhance" model for GPR3 activation. Our study provides a starting framework for the understanding of GPR3 signaling in cold-stimulated thermogenesis.

Dynamic expression pattern of Pde4d and its relationship with CpG methylation in the promoter during mouse embryo development.

Mouse Pde4d is located on chromosome 13 and serves many functions in important physiological processes involving cyclic adenosine monophosphate. In this study, imprinting analysis indicated that Pde4d exhibits a dynamic and specific allelic expression pattern during embryo development. This showed paternal-origin sex bias in embryonic day 9.5 (E9.5) whole embryos and placenta, and biallelic expression in the major embryonic organs and placenta at E15.5. In situ hybridization determined the spatiotemporal expression pattern of Pde4d in mouse embryos from the mid- to late-embryonic stages. This demonstrated that Pde4d was widely expressed in the neural tissues, including the forebrain, midbrain, hindbrain, and neural tube, at the mid-embryonic stage. By the late-embryonic stage, Pde4d was extensively detected throughout the developing organism, including in the liver, brain, lung, kidney, and tongue. In addition, methylation analyses indicated that tissue-specific CpG methylation of the Pde4d promoter was correlated with Pde4d mRNA expression in major E15.5 tissues. Furthermore, stage-specific CpG methylation of the Pde4d promoter was associated with gene expression in the liver at three developmental stages. Our results suggest that Pde4d might serve specific biological functions in regulating the development process of the mouse embryo, and that CpG methylation of the Pde4d promoter may play an important role in regulating Pde4d at a transcriptional level.

Meg8-DMR as the Secondary Regulatory Region Regulates the Expression of MicroRNAs While It Does Not Affect Embryonic Development in Mice.

Meg8-DMR is the first maternal methylated DMR to be discovered in the imprinted Dlk1-Dio3 domain. The deletion of Meg8-DMR enhances the migration and invasion of MLTC-1 depending on the CTCF binding sites. However, the biological function of Meg8-DMR during mouse development remains unknown. In this study, a CRISPR/Cas9 system was used to generate 434 bp genomic deletions of Meg8-DMR in mice. High-throughput and bioinformatics profiling revealed that Meg8-DMR is involved in the regulation of microRNA: when the deletion was inherited from the mother (Mat-KO), the expression of microRNA was unchanged. However, when the deletion occurred from the father (Pat-KO) and homozygous (Homo-KO), the expression was upregulated. Then, differentially expressed microRNAs (DEGs) were identified between WT with Pat-KO, Mat-KO, and Homo-KO, respectively. Subsequently, these DEGs were subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) term enrichment analysis to explore the functional roles of these genes. In total, 502, 128, and 165 DEGs were determined. GO analysis showed that these DEGs were mainly enriched in axonogenesis in Pat-KO and Home-KO, while forebrain development was enriched in Mat-KO. Finally, the methylation levels of IG-DMR, Gtl2-DMR, and Meg8-DMR, and the imprinting status of Dlk1, Gtl2, and Rian were not affected. These findings suggest that Meg8-DMR, as a secondary regulatory region, could regulate the expression of microRNAs while not affecting the normal embryonic development of mice.

Plk1-mediated phosphorylation of UAP56 regulates the stability of UAP56.

Polo-like kinase 1 (Plk1) is a conserved serine/threonine protein kinase that plays pivotal roles during the cell cycle and cell proliferation. Although a number of important targets have been identified, the mechanism of Plk1-regulated pathways and the bulk of the Plk1 interactome are largely unknown. Here, we demonstrate that Plk1 interacts with the DExH/D RNA helicase, UAP56. The protein levels of UAP56 and Plk1 are inversely correlated during the cell cycle. We also show that Plk1 phosphorylates UAP56 in vitro and in vivo and that Plk1-dependent phosphorylation of UAP56 triggers ubiquitination and degradation of UAP56 through proteasomes. This result suggests that Plk1-mediated phosphorylation of UAP56 regulates the stability of UAP56. Our results will be helpful in further understanding mRNA metabolism, cell cycle progression, and the link between mRNA metabolism and cellular function.

Trmt112 gene expression in mouse embryonic development.

Mouse Trmt112, the homologous gene of yeast Trm112 (tRNA methyltransferase 11-2), was initially cloned from RIKEN with uncertain function. The yeast TRM112 is now known to play important roles in RNA methylation. Here, we studied the expression of Trmt112 by in situ hybridization and quantitative real-time RT-PCR (QRT-PCR). A higher expression level of Trmt112 was observed in the brain and nervous system by whole mount in situ hybridization from embryonic day 10.5 (E10.5) to E11.5. At later developmental stages E13.5 and E16.5, abundant expression was prominently found in various organs and tissues including developing brain, nervous system, thymus, lung, liver, intestine, kidney, and cartilage. Furthermore, Trmt112 was persistently expressed from E9.5 to E18.5 on whole embryos and highly expressed in multiple organs at E12.5, E15.5 and E18.5 by QRT-PCR. These results showed that Trmt112 gene was highly and ubiquitously expressed during mouse embryonic development, implying that it might be involved in the morphogenesis of diverse organs and tissues and numerous physiological functions.

Malignant transformation of 293 cells induced by ectopic expression of human Nanog.

Tumor development has long been known to resemble abnormal embryogenesis. The ESC self-renewal gene NANOG is purportedly expressed in some epithelial cancer cells and solid tumors, but a casual role in tumor development has remained unclear. In order to more comprehensively elucidate the relationship between human Nanog and tumorigenesis, the hNanog was ectopically expressed in the 293 cell line to investigate its potential for malignant transformation of cells both in vitro and in vivo. Here we provide compelling evidence that the overexpression of hNanog resulted in increased cell proliferation, anchor-independent growth in soft agar, and formation of tumors after subcutaneous injection of athymic nude mice. Pathologic analysis revealed that these tumors were poorly differentiated. In analysis of the underlying molecular mechanism, two proteins, FAK and Ezrin, were identified to be upregulated in the hNanog expressing 293 cells. Our results demonstrate that hNanog is a potent human oncogene and has the ability to induce cellular transformation of human cells.

Characterization and potential function of a novel pre-implantation embryo-specific RING finger protein: TRIML1.

Members of the super-class of zinc finger proteins are key regulators in early embryogenesis. Utilizing in silico mining of EST Databases for pre-implantation Embryo-Specific Zinc Finger Protein Genes, we characterized a novel zygotic mouse gene-tripartite motif family-like 1 (TRIML1), which expresses in embryo before implantation. Knocking down of TRIML1 resulted in the fewer cell number of blastocysts and failture to give rise to neonates after embryo transfer. The binding partner of TRIML1, Ubiquitin-specific protease 5 (USP5), was identified by yeast two-hybrid screening assay. The interaction was confirmed by GST pull-down and coimmunoprecipitation analysis. The role of TRIML1 in ubiquitin pathway during the development stage of mouse blastocyst was further discussed.

Towards Functional Annotation of the Preimplantation Transcriptome: An RNAi Screen in Mammalian Embryos.

With readily available transcriptome-wide data, understanding the role of each expressed gene is an essential next step. Although RNAi technologies allow for genome-wide screens in cell culture, these approaches cannot replace strategies for discovery in the embryo. Here we present, for the first time, a knockdown screen in mouse preimplantation embryos. Early mammalian development encompasses dynamic cellular, molecular and epigenetic events that are largely conserved from mouse to man. We assayed 712 genes for requirements during preimplantation. We identified 59 genes required for successful development or outgrowth and implantation. We have characterized each phenotype and revealed cellular, molecular, and lineage specific defects following knockdown of transcript. Induced network analyses demonstrate this as a valid approach to identify networks of genes that play important roles during preimplantation. Our approach provides a robust and efficient strategy towards identification of novel phenotypes during mouse preimplantation and facilitates functional annotation of the mammalian transcriptome.

Computational identification of putative lincRNAs in mouse embryonic stem cell.

As the regulatory factors, lncRNAs play critical roles in embryonic stem cells. And lincRNAs are most widely studied lncRNAs, however, there might still might exist a large member of uncovered lncRNAs. In this study, we constructed the de novo assembly of transcriptome to detect 6,701 putative long intergenic non-coding transcripts (lincRNAs) expressed in mouse embryonic stem cells (ESCs), which might be incomplete with the lack coverage of 5' ends assessed by CAGE peaks. Comparing the TSS proximal regions between the known lincRNAs and their closet protein coding transcripts, our results revealed that the lincRNA TSS proximal regions are associated with the characteristic genomic and epigenetic features. Subsequently, 1,293 lincRNAs were corrected at their 5' ends using the putative lincRNA TSS regions predicted by the TSS proximal region prediction model based on genomic and epigenetic features. Finally, 43 putative lincRNAs were annotated by Gene Ontology terms. In conclusion, this work provides a novel catalog of mouse ESCs-expressed lincRNAs with the relatively complete transcript length, which might be useful for the investigation of transcriptional and post-transcriptional regulation of lincRNA in mouse ESCs and even mammalian development.

Parthenogenetic activation of mouse oocytes by strontium chloride: a search for the best conditions.

Strontium has been successfully used to induce activation of mouse oocytes in nuclear transfer and other experiments, but the optimum treatment conditions have not been studied systematically. When cumulus-free oocytes were treated with 10mM SrCl(2) for 0.5-5h, activation rates (88.4+/-4.1 to 91.2+/-2.7%) did not differ (mean+/-S.E.; P>0.2), but rate of blastulation (57.3+/-3.5%) and cell number per blastocyst (45.0+/-2.4) were the highest after treatment for 2.5h. When treated with 1-20mM SrCl(2) for 2.5h, the activation rate and cell number per blastocyst were higher (P<0.02) after 10mM SrCl(2) treatment than other treatments. The best activation and development were obtained with Ca(2+)-free Sr(2+) medium, but the activation rate was low (37.7+/-1.6%) in Ca(2+)-containing medium. Activation rates were the same, regardless of the presence or absence of cytochalasin B (CB) in the activating medium, but the blastulation rate was higher (P<0.001) in the presence of CB. Only 70% of the cumulus-enclosed oocytes were activated and 10% blastulated after a 10 min exposure to 1.6mM SrCl(2), and many lysed, with increased intensity of Sr(2+) treatment. The presence of CB in SrCl(2) medium markedly reduced lysis of cumulus-enclosed oocytes. Media M16 and CZB did not differ when used as activating media. Only 10.5% of the oocytes collected 13 h post hCG were activated by Sr(2+) treatment alone, with 34% blastulating, but rates of activation and blastulation increased (P<0.001) to 94 and 60%, respectively, when they were further treated with 6-dimethylaminopurine (6-DMAP). The total and ICM cell numbers were less (P<0.001) in parthenotes than in the in vivo fertilized embryos. In conclusion, the concentration and duration of SrCl(2) treatment and the presence or absence of CB in activating medium and cumulus cells had marked effects on mouse oocyte activation and development. To obtain the best activation and development, cumulus-free oocytes collected 18 h post hCG should be treated for 2.5h with 10mM SrCl(2) in Ca(2+)-free medium supplemented with 5 microg/mL of CB.

The effect of follicle-stimulating hormone on follicular development, granulosa cell apoptosis and steroidogenesis and its mediation by insulin-like growth factor-I in the goat ovary.

The effect of FSH on goat follicular development, granulosa cell apoptosis and steroidogenesis and its mediation by insulin-like growth factor (IGF)-I were studied through both in vivo and in vitro experiments. The FSH treatment was begun on Day 9 after estrus and consisted of injections twice a day for 3 days in decreasing doses (7.5-7.5-5.0-5.0-2.5-2.5 mg). Does in both treatment and control groups were slaughtered for ovaries on Day 12. Granulosa cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Expression of IGF-I and IGF-II mRNA was determined by RT-PCR, while concentrations of progesterone (P4), estradiol (E2), IGF-I and IGF-II were measured by radioimmunoassay (RIA). Following parameters increased significantly (P<0.05) after the FSH treatment: follicle number (5.0+/-1.5 versus 9.0+/-2.0 per ovary), the level of E2 (0.1+/-0.1 ng/ml versus 0.7+/-0.2 ng/ml), the E2/P4 ratio (0.7+/-0.4 versus 4.7+/-3.0) and the concentrations of IGF-I (0.5+/-0.2 ng/ml versus 119.4+/-15.1 ng/ml) and IGF-II (0.12+/-0.03 ng/ml versus 40.9+/-18.7 ng/ml) in follicular fluid of the medium sized (3-5 mm) follicles and in the ovarian cortex the relative quantity of IGF-I mRNA (0.37+/-0.17 versus 0.90+/-0.12 Max OD). In contrast, the ratio of apoptotic granulosa cells in these follicles was reduced significantly (0.53+/-0.1 versus 0.10+/-0.01, P<0.05). In large (>5 mm) follicles, however, only the follicle number (2.3+/-0.7 versus 7.0+/-1.5 per ovary) and the level of IGF-I (38.4+/-11.0 ng/ml versus 87.3+/-13.9 ng/ml) increased significantly (P<0.05), whereas other values did not change. In vitro culture of granulosa cells showed that FSH significantly (P<0.05) enhanced IGF-I production (12.7+/-2.1 ng/ml versus 26.+/-21.9 ng/ml) by these cells, and both FSH and IGF-I reduced the ratios of apoptotic cells (from 0.7+/-0.07 to 0.3+/-0.1 and 0.2+/-0.04, respectively) and the effect was additive when both were used together. H89, the PKA pathway inhibitor, blocked the effect of FSH on granulosa cell apoptosis and IGF-I production in vitro. These results indicated that FSH mainly enhanced the development of medium sized follicles in the goat by suppressing the apoptosis of granulosa cells via increasing production of IGF-I and steroids, possibly through the PKA pathway.

Spatiotemporal expression of retrogene-host pair Mcts2/H13 in mouse embryo, and Mcts2 has no influence on H13 transcription pattern in NIH/3T3 cells.

Mcts2 and H13 comprise an imprinted retrogene-host gene pair. Imprinted genes have been proved to be closely related with embryo development. In order to understand its expression relationship during embryo development and influence of the retrogene on the host gene, we studied expression patterns in mouse embryos and transcriptional interference in a cell culture system. The present study determined the spatio-temporal expression pattern of Mcts2 and H13 from embryonic day 9.5 to 15.5. A similar expression pattern between Mcts2 and H13 was observed in mouse embryogenesis by in situ hybridization and real-time PCR, these two genes were extensively expressed in the neural tissues at mid-embryonic stages. As the embryo development proceeded, H13 and Mcts2 were widely detected throughout the developing organism, especially highly expressed in brain. Moreover, neither over expression nor knockdown of Mcts2 has any significant detectable effect on H13 expression in NIH/3T3 cells. In addition, transcriptional up-regulation of Mcts2 caused by demethylation of DMR in the Mcts2 promoter was not directly associated with the H13 transcription in NIH/3T3 cells treated by 5-Aza-cdR. The regulatory relationship between H13 transcripts and the promoter methylation status of Mcts2 was complex, demonstrating host/retrogene relationship may not be limited to the imprinted locus.

DNA methylation dynamics of a maternally methylated DMR in the mouse Dlk1-Dio3 domain.

The mouse delta-like homolog 1 and type III iodothyronine deiodinase (Dlk1-Dio3) imprinted domain contains three known paternally methylated differentially methylated regions (DMRs): intergenic DMR (IG-DMR), maternally expressed 3-DMR (Gtl2-DMR), and Dlk1-DMR. Here, we report the first maternally methylated DMR, CpG island 2 (CGI-2), is located approximately 800 bp downstream of miR-1188. CGI-2 is highly methylated in sperm and oocytes, de-methylated in pre-implantation embryos, and differentially re-methylated during post-implantation development. CGI-2, similarly to Gtl2-DMR and Dlk1-DMR, acquires differential methylation prior to embryonic day 7.5 (E7.5). Both H3K4me3 and H3K9me3 histone modifications are enriched at CGI-2. Furthermore, CCCTC-binding factor (CTCF) binds to both alleles of CGI-2 in vivo. These results contribute to the investigation of imprinting regulation in this domain.

Expression and imprinting analysis of AK044800, a transcript from the Dlk1-Dio3 imprinted gene cluster during mouse embryogenesis.

Recent advances of induced pluripotent stem cells (iPSCs) has demonstrated that full development potential is closely related with the expression state of noncoding RNAs (ncRNAs) of the Dlk1-Dio3 imprinted gene cluster. However, few of them, especially the long noncoding RNAs (lncRNAs), have been characterized in detail. AK044800 is a transcript from the Dlk1-Dio3 imprinted region with little known information. This study reports original data on the expression pattern of AK044800 during embryogenesis. Expression analysis showed that AK044800 was specifically expressed in the brain at mid-gestation, E9.5 and E11.5. And at E15.5, its expression was mainly concentrated in the forebrain. In the late-gestation stage (E18.5), AK044800 expression was weaker in the brain and began to emerge in some other tissues during this period. Notably, the expression of AK044800 was biallelic in the brain, unlike other noncoding transcripts from this imprinted region. In addition, its expression was dependent on inbred mouse strains. This may be the first lncRNA that has been identified with a different expression between inbred mouse strains. This study may provide useful clues for further investigations of expression regulation and functions of lncRNAs of the Dlk1-Dio3 imprinted region.