LncGMDS-AS1 promotes the tumorigenesis of colorectal cancer through HuR-STAT3/Wnt axis.

Chronic inflammation promotes the tumorigenesis and cell stemness maintenance of colorectal cancer (CRC). However, the bridge role of long noncoding RNA (lncRNA) in linking chronic inflammation to CRC development and progression needs better understanding. Here, we elucidated a novel function of lncRNA GMDS-AS1 in persistently activated signal transducer and transcription activator 3 (STAT3) and Wnt signaling and CRC tumorigenesis. Interleukin-6 (IL-6) and Wnt3a induced lncRNA GMDS-AS1 expression, which was highly expressed in the CRC tissues and plasma of CRC patients. GMDS-AS1 knockdown impaired the survival, proliferation and stem cell-like phenotype acquisition of CRC cells in vitro and in vivo. We performed RNA sequencing (RNA-seq) and mass spectrometry (MS) to probe target proteins and identify their contributions to the downstream signaling pathways of GMDS-AS1. In CRC cells, GMDS-AS1 physically interacted with the RNA-stabilizing protein HuR, thereby protecting the HuR protein from polyubiquitination- and proteasome-dependent degradation. HuR stabilized STAT3 mRNA and upregulated the levels of basal and phosphorylated STAT3 protein, persistently activating STAT3 signaling. Our research revealed that the lncRNA GMDS-AS1 and its direct target HuR constitutively activate STAT3/Wnt signaling and promote CRC tumorigenesis, the GMDS-AS1-HuR-STAT3/Wnt axis is a therapeutic, diagnostic and prognostic target in CRC.

The histone demethylase Kdm6b regulates the maturation and cytotoxicity of TCRαß+CD8αα+ intestinal intraepithelial lymphocytes.

Intestinal intraepithelial lymphocytes (IELs) are distributed along the length of the intestine and are considered the frontline of immune surveillance. The precise molecular mechanisms, especially epigenetic regulation, of their development and function are poorly understood. The trimethylation of histone 3 at lysine 27 (H3K27Me3) is a kind of histone modifications and associated with gene repression. Kdm6b is an epigenetic enzyme responsible for the demethylation of H3K27Me3 and thus promotes gene expression. Here we identified Kdm6b as an important intracellular regulator of small intestinal IELs. Mice genetically deficient for Kdm6b showed greatly reduced numbers of TCRαß+CD8αα+ IELs. In the absence of Kdm6b, TCRαß+CD8αα+ IELs exhibited increased apoptosis, disturbed maturation and a compromised capability to lyse target cells. Both IL-15 and Kdm6b-mediated demethylation of histone 3 at lysine 27 are responsible for the maturation of TCRαß+CD8αα+ IELs through upregulating the expression of Gzmb and Fasl. In addition, Kdm6b also regulates the expression of the gut-homing molecule CCR9 by controlling H3K27Me3 level at its promoter. However, Kdm6b is dispensable for the reactivity of thymic precursors of TCRαß+CD8αα+ IELs (IELPs) to IL-15 and TGF-ß. In conclusion, we showed that Kdm6b plays critical roles in the maturation and cytotoxic function of small intestinal TCRαß+CD8αα+ IELs.

Bcl-3 promotes TNF-induced hepatocyte apoptosis by regulating the deubiquitination of RIP1.

Tumor necrosis factor-α (TNF) is described as a main regulator of cell survival and apoptosis in multiple types of cells, including hepatocytes. Dysregulation in TNF-induced apoptosis is associated with many autoimmune diseases and various liver diseases. Here, we demonstrated a crucial role of Bcl-3, an IκB family member, in regulating TNF-induced hepatic cell death. Specifically, we found that the presence of Bcl-3 promoted TNF-induced cell death in the liver, while Bcl-3 deficiency protected mice against TNF/D-GalN induced hepatoxicity and lethality. Consistently, Bcl-3-depleted hepatic cells exhibited decreased sensitivity to TNF-induced apoptosis when stimulated with TNF/CHX. Mechanistically, the in vitro results showed that Bcl-3 interacted with the deubiquitinase CYLD to synergistically switch the ubiquitination status of RIP1 and facilitate the formation of death-inducing Complex II. This complex further resulted in activation of the caspase cascade to induce apoptosis. By revealing this novel role of Bcl-3 in regulating TNF-induced hepatic cell death, this study provides a potential therapeutic target for liver diseases caused by TNF-related apoptosis.

A Robust Panel Based on Mitochondrial Localized Proteins for Prognostic Prediction of Lung Adenocarcinoma.

Due to high energy and material metabolism requirements, mitochondria are frequently active in tumor cells. Our study found that the high energy metabolism status is positively correlated with the poor prognosis of patients with lung adenocarcinoma. We constructed a scoring system (mitoRiskscore) based on the gene expression of specific mitochondrial localized proteins through univariate and LASSO cox regression. It has been shown that high mitoRiskscore was correlated with a shorter survival time after surgery in patients with lung adenocarcinoma. Compared with the typical TNM grading system, the mitoRiskscore gene panel had higher prediction accuracy. A vast number of external verification results ensured its universality. Additionally, the mitoRiskscore could evaluate the metabolic pattern and chemotherapy sensitivity of the tumor samples. Lung adenocarcinoma with higher mitoRiskscore was more active in glycolysis, and oxidative phosphorylation expression of proliferation-related pathway genes was also significantly upregulated. In contrast, patients with low mitoRiskscore had similar metabolic patterns to normal tissues. In order to improve the accuracy of prediction ability and promote clinical usage, we developed a nomogram that combined mitoRiskscore and clinical prognostic factors to predict the 3-year, 5-year, and 10-year survival rates of patients. We also performed in vitro experiments to verify the function of the key genes in the mitoRiskscore panel. In conclusion, the mitoRiskscore scoring system may assist clinicians to judge the postoperative survival rate and chemotherapy of patients with lung adenocarcinoma.

Loss of p53 in mesenchymal stem cells promotes alteration of bone remodeling through negative regulation of osteoprotegerin.

p53 plays a pivotal role in controlling the differentiation of mesenchymal stem cells (MSCs) by regulating genes involved in cell cycle and early steps of differentiation process. In the context of osteogenic differentiation of MSCs and bone homeostasis, the osteoprotegerin/receptor activator of NF-κB ligand/receptor activator of NF-κB (OPG/RANKL/RANK) axis is a critical signaling pathway. The absence or loss of function of p53 has been implicated in aberrant osteogenic differentiation of MSCs that results in higher bone formation versus erosion, leading to an unbalanced bone remodeling. Here, we show by microCT that mice with p53 deletion systemically or specifically in mesenchymal cells possess significantly higher bone density than their respective littermate controls. There is a negative correlation between p53 and OPG both in vivo by analysis of serum from p53+/+, p53+/-, and p53-/- mice and in vitro by p53 knockdown and ChIP assay in MSCs. Notably, high expression of Opg or its combination with low level of p53 are prominent features in clinical cancer lesion of osteosarcoma and prostate cancer respectively, which correlate with poor survival. Intra-bone marrow injection of prostate cancer cells, together with androgen can suppress p53 expression and enhance local Opg expression, leading to an enhancement of bone density. Our results support the notion that MSCs, as osteoblast progenitor cells and one major component of bone microenvironment, represent a cellular source of OPG, whose amount is regulated by the p53 status. It also highlights a key role for the p53-OPG axis in regulating the cancer associated bone remodeling.

Critical role of histone H3 lysine 27 demethylase Kdm6b in the homeostasis and function of medullary thymic epithelial cells.

Medullary thymic epithelial cells (mTECs) play a central role in the establishment of T cell central immunological tolerance by promiscuously expressing tissue-restricted antigens (TRAs) and presenting them to developing T cells, leading to deletion of T cells responding to self-antigens. However, molecular mechanisms especially epigenetic regulation of mTEC homeostasis and TRA expression remain elusive. Here we show that the H3K27 demethylase Kdm6b is essential to maintain the postnatal thymic medulla by promoting mTEC survival and regulating the expression of TRA genes. Moreover, mice lacking Kdm6b developed pathological autoimmune disorders. Mechanically, Kdm6b exerted its function by reducing repressive H3K27 trimethylation (H3K27me3) at the promoters of anti-apoptotic gene Bcl2 and a set of Aire-dependent TRA genes. Thus, our findings reveal a dual role of Kdm6b in the regulation of mTEC-mediated T cell central tolerance.

Integrin-ß4 is a novel transcriptional target of TAp73.

As a member of p53 family, p73 has attracted intense investigations due to its structural and functional similarities to p53. Among more than ten p73 variants, the transactivation (TA) domain-containing isoform TAp73 is the one that imitates the p53's behavior most. TAp73 induces apoptosis and cell cycle arrest, which endows it the capacity of tumour suppression. Also, it can exert diverse biological influences on cells through activating a complex and context dependent transcriptional programme. The transcriptional activities further broaden its roles in more intricate biological processes. In this article, we report that p73 is a positive regulator of a cell adhesion related gene named integrin ß4 (ITGB4). This finding may have implications for the dissection of the biological mechanisms underlining p73 functions.

Mesenchymal stem cells: a new strategy for immunosuppression and tissue repair.

Mesenchymal stem cells (MSCs) have great potential for treating various diseases, especially those related to tissue damage involving immune reactions. Various studies have demonstrated that MSCs are strongly immunosuppressive in vitro and in vivo. Our recent studies have shown that un-stimulated MSCs are indeed incapable of immunosuppression; they become potently immunosuppressive upon stimulation with the supernatant of activated lymphocytes, or with combinations of IFN-gamma with TNF-alpha, IL-1alpha or IL-1beta. This observation revealed that under certain circumstances, inflammatory cytokines can actually become immunosuppressive. We showed that there is a species variation in the mechanisms of MSC-mediated immunosuppression: immunosuppression by cytokine-primed mouse MSCs is mediated by nitric oxide (NO), whereas immunosuppression by cytokine-primed human MSCs is executed through indoleamine 2, 3-dioxygenase (IDO). Additionally, upon stimulation with the inflammatory cytokines, both mouse and human MSCs secrete several leukocyte chemokines that apparently serve to attract immune cells into the proximity with MSCs, where NO or IDO is predicted to be most active. Therefore, immunosuppression by inflammatory cytokine-stimulated MSCs occurs via the concerted action of chemokines and immune-inhibitory NO or IDO produced by MSCs. Thus, our results provide novel information about the mechanisms of MSC-mediated immunosuppression and for better application of MSCs in treating tissue injuries induced by immune responses.