Embryonic stem cell related gene regulates alternative splicing of transcription factor 3 to maintain human embryonic stem cells' self-renewal and pluripotency.

Exploring the mechanism of self-renewal and pluripotency maintenance of human embryonic stem cells (hESCs) is of great significance in basic research and clinical applications, but it has not been fully elucidated. Long non-coding RNAs (lncRNAs) have been shown to play a key role in the self-renewal and pluripotency maintenance of hESCs. We previously reported that the lncRNA ESRG, which is highly expressed in undifferentiated hESCs, can maintain the self-renewal and pluripotency of hPSCs. RNA pull-down mass spectrometry showed that ESRG could bind to other proteins, among which heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) attracted our attention. In this study, we showed that HNRNPA1 can maintain self-renewal and pluripotency of hESCs. ESRG bound to and stabilized HNRNPA1 protein through the ubiquitin-proteasome pathway. In addition, knockdown of ESRG or HNRNPA1 resulted in alternative splicing of TCF3, which originally and primarily encoded E12, to mainly encode E47 and inhibit CDH1 expression. HNRNPA1 could rescue the biological function changes of hESCs caused by ESRG knockdown or overexpression. Our results suggest that ESRG regulates the alternative splicing of TCF3 to affect CDH1 expression and maintain hESCs self-renewal and pluripotency by binding and stabilizing HNRNPA1 protein. This study lays a good foundation for exploring the new molecular regulatory mechanism by which ESRG maintains hESCs self-renewal and pluripotency.

ESRG, LINC00518 and PWRN1 are newly-identified deregulated lncRNAs in colorectal cancer.

Colorectal cancer is the 2nd leading cause of death in humans because of cancer. This rank of death could be due to the high rate of incidence from one hand, and the lack of sufficient diagnostic and therapeutic approaches from the other hand. Thus, molecular tools have been emerging as the potential biomarker to improve the early diagnosis and therapeutic management that subsequently could lead to the heightened survival rate of colorectal cancer patients. Long non-coding RNA (lncRNAs) have shown promising capabilities to be used in clinics. The profiling methods could identify novel aberrantly expressed lncRNAs in colorectal cancer. We, thus, performed a comprehensive and unbiased approach to shortlist the dysregulated lncRNAs based on the colon adenocarcinoma TCGA data. An unbiased in silico method was used to rank the yet to profiled lncRNAs in colorectal cancer. qPCR was used to measure the expression level of selected lncRNAs. Our results nominated ESRG, LINC00518, PWRN1, and TTTY14 lncRNAs as the top-hit novel lncRNAs with aberrant expression in colon cancer. The qPCR method was used to profile these lncRNAs that showed the up-regulation of ESRG and LINC00518, and down-regulation of TTTY14 in thirty paired colorectal cancer specimens. The statistical analyses demonstrated that ESRG, LINC00518 and PWRN1 could distinguish the tumor from normal samples. Moreover, ESRG showed a negative correlation with the overall survival of patients. These diagnostic and prognostic results suggest that profiling ESRG, LINC00518 and PWRN1 s may have implications in clinics.

An ESRG-interacting protein, COXII, is involved in pro-apoptosis of human embryonic stem cells.

Human embryonic stem cells(hESC) posses very promising application perspective in clinical transplant therapies for their characteristics of self-renewal and pluripotency. So efforts focusing on the mechanisms of the two characteristics are extremely important. ESRG, first identified by our group, is a candidate stemness gene of hESC for its much higher expression level in hESC comparing to that in 7-day embryoid bodies(EBs). Here, the proteins interacted with ESRG and its functions in hESC were explored. Yeast two-hybrid (Y2H) screening system was adopted to explore the interacting proteins of ESRG. Then Co-IP was performed to confirm the interactions between candidate proteins and ESRG. At last, the functions of validated interacting protein were explored by RNA interference(RNAi) and Western blot(WB). There were no autonomous activation and toxicity in the Y2H system, which verified its availability. Four candidate proteins, AAMP, DDT, GNB2L1 and COXII, were discovered, and the interaction between ESRG and COXII was ultimately confirmed. The expression of COXII in hESC was suppressed by siRNA, and the inhibited mitochondrial apoptosis was observed in hESC with downregulated COXII expression. Our work first validated the interaction between ESRG and COXII, and demonstrated that COXII serves as a pro-apoptotic protein in hESC. The results implied that ESRG may play an important role in regulating the apoptosis of hESC by interacting with COXII, and thus contribute a lot to the maintenance of hESC characteristics.

Pan-Cancer Analysis Reveals Long Non-coding RNA (lncRNA) Embryonic Stem Cell-Related Gene (ESRG) as a Promising Diagnostic and Prognostic Biomarker.

BACKGROUND: Embryonic stem cell-related gene (ESRG; also known as HESRG) is a long non-coding RNA (lncRNA). It is involved in the regulation of human pluripotent stem cells (hPSCs) self-renewal. ESRG gene has the ability to interact with chromatins, different RNA types, and RNA binding proteins (RBP); thus making ESRG be considered an oncogenic lncRNA, where its expression is detected in various tumor tissues. This study aimed to evaluate the prospective diagnostic and prognostic values of ESRG in various human cancers. MATERIALS AND METHODS: The expression of ESRG in various cancers was analyzed using the Gene Expression Profiling Interactive Analysis (GEPIA), Tumor Immune Estimation Resource (TIMER), and University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN) databases. Moreover, the correlation between the expression of ESRG and clinical pathological parameters was analyzed using UALCAN. The effect of ESRG expression on the survival outcome was evaluated using Kaplan-Meier plotter, UALCAN, GEPIA, and TIMER. The correlation between ESRG expression and immune cell infiltration was studied by TIMER. Additionally, the genetic alterations were investigated cBioportal. Our findings were validated using the GEO2R database. RESULTS: Our results showed ESRG to be significantly up-regulated in colon adenocarcinoma (COAD) and lung squamous cell carcinoma (LUSC) with p<0.001, in addition to rectum adenocarcinoma (READ), and uterine carcinosarcoma (UCEC) with p<0.01. Regarding pathogenic stages, there was a significant upregulation in stages 2, 3, and 4 compared to normal in COAD and stages 1, 2, and 3 for LUSC patients. The combined prognostic analysis showed that the up-regulated expression of ESRG was associated with better survival outcomes in patients with brain lower-grade glioma (LGG). Our results demonstrate a significant negative correlation between ESRG expression and the abundance of CD8+T cells in COAD, READ, LUSC, and UCEC. Additionally, ESRG was mutated in 0.77 (<1%) of the queried samples, and the most prevalent ESRG mutations are deep deletion mutations, followed by amplification. CONCLUSION: Analysis of ESRG across various cancer types elucidated its potential to be used as a diagnostic biomarker in COAD, LUSC, READ, and UCEC and a promising prognostic biomarker in LGG. Our findings provide useful insights for future research.

ESRG is critical to maintain the cell survival and self-renewal/pluripotency of hPSCs by collaborating with MCM2 to suppress p53 pathway.

The mechanisms of self-renewal and pluripotency maintenance of human pluripotent stem cells (hPSCs) have not been fully elucidated, especially for the role of those poorly characterized long noncoding RNAs (lncRNAs). ESRG is a lncRNA highly expressed in hPSCs, and its functional roles are being extensively explored in the field. Here, we identified that the transcription of ESRG can be directly regulated by OCT4, a key self-renewal factor in hPSCs. Knockdown of ESRG induces hPSC differentiation, cell cycle arrest, and apoptosis. ESRG binds to MCM2, a replication-licensing factor, to sustain its steady-state level and nuclear location, safeguarding error-free DNA replication. Further study showed that ESRG knockdown leads to MCM2 abnormalities, resulting in DNA damage and activation of the p53 pathway, ultimately impairs hPSC self-renewal and pluripotency, and induces cell apoptosis. In summary, our study suggests that ESRG, as a novel target of OCT4, plays an essential role in maintaining the cell survival and self-renewal/pluripotency of hPSCs in collaboration with MCM2 to suppress p53 signaling. These findings provide critical insights into the mechanisms underlying the maintenance of self-renewal and pluripotency in hPSCs by lncRNAs.

Universal Markers for hiPSCs Residue Detection.

BACKGROUND: Residual undifferentiated induced pluripotent stem cells (iPSCs) detection is essential for both Embryonic Stem Cells (ESCs) and iPSCs application in final cell therapy products. However, specific differentiated cells require specific genes for residual detection; identifying the suitable marker is costly and time-consuming. Thus, a universal marker for iPSCs residue detection for all three germline cells would greatly benefit PSC-derived cellular therapies. METHODS: Next-generation sequencing (NGS) was performed on total RNAs isolated from the iPSC cell lines and embryonic stem cells (H9), the top 30 expressed genes were selected as candidates. By analysis expression fold change comparing iPSC cells to the differentiated cells, seven genes were highly expressed in iPSCs but showed minimal background expression in differentiated cells. Tissue expression pattern of the candidate genes were explored in the Genotype-Tissue Expression (GTEx) project database, candidate genes were narrowed down to two genes. Spike-in experiments were performed to determine the detection limit and correlation with the number of iPSCs and gene expression by ddPCR. RESULTS: By next-generation sequencing (NGS), we identified two marker genes (ESRG and ZSCAN10) suitable for universal undifferentiated iPSC detection. Both ESRG and ZSCAN10 are highly expressed in iPSCs. ZSCAN10 is slightly expressed in the testis, pituitary, and cerebellum; ESRG is highly expressed in the vagina and scarcely expressed in the other tissues. Furthermore, the ddPCR method with a probe and primers for ESRG and ZSCAN10 detected a trace of undifferentiated hiPSCs to a spiked level of 0.0001%. CONCLUSIONS: These results suggest that targeting ESRG/ZSCAN10 transcripts is highly sensitive, quantitative, and could be broadly applied to quality control of almost all iPSC-derived cell therapy products.