Xiao-Shun He

Ubiquitin-Specific Protease 4-Mediated Deubiquitination and Stabilization of PRL-3 Is Required for Potentiating Colorectal Oncogenesis

Ubiquitin specific protease 4 (USP4) is a deubiquitinating enzyme with key roles in the regulation of p53 and TGFβ signaling, suggesting its importance in tumorigenesis. However, the mechanisms and regulatory roles of USP4 in cancer, including colorectal cancer, remain largely elusive. Here, we present the first evidence that USP4 regulates the growth, invasion, and metastasis of colorectal cancer. USP4 expression was significantly elevated in colorectal cancer tissues and was significantly associated with tumor size, differentiation, distant metastasis, and poor survival. Knockdown of USP4 diminished colorectal cancer cell growth, colony formation, migration, and invasion in vitro and metastasis in vivo. Importantly, we found that phosphatase of regenerating liver-3 (PRL-3) is indispensable for USP4-mediated oncogenic activity in colorectal cancer. Mechanistically, we observed that USP4 interacted with and stabilized PRL-3 via deubiquitination. This resulted in activation of Akt and reduction of E-cadherin, critical regulators of cancer cell growth and metastasis. Examination of clinical samples confirmed that USP4 expression positively correlates with PRL-3 protein expression, but not mRNA transcript levels. Taken together, our results demonstrate that aberrant expression of USP4 contributes to the development and progression of colorectal cancer and reveal a critical mechanism underlying USP4-mediated oncogenic activity. These observations suggest that the potential of harnessing proteolytic degradation processes for therapeutic manipulation may offer a much-needed new approach for improving colorectal cancer treatment strategies.

NUR77 exerts a protective effect against inflammatory bowel disease by negatively regulating the TRAF6/TLR-IL-1R signalling axis.

Nur77, an immediate‐early response gene, participates in a wide range of biological functions. Its human homologue, NUR77, is known by several names and has the HGNC‐approved gene symbol NR4A1. However, the role of Nur77 in inflammatory bowel disease (IBD) and its underlying mechanisms remain elusive. Here, using public data from the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC) on the most recent genome‐wide association studies (GWAS) for ulcerative colitis (UC) and Crohns disease (CD), we found that genetic variants of the NUR77 gene are associated with increased risk for both UC and CD. Accordingly, Nur77 expression was significantly reduced in colon tissues from patients with UC or CD and mice treated with DSS. Nur77 deficiency increased the susceptibility of mice to DSS‐induced experimental colitis and prevented intestinal recovery, whereas treatment with cytosporone B (Csn‐B), an agonist for Nur77, significantly attenuated excessive inflammatory response in the DSS‐induced colitis mouse model. Mechanistically, NUR77 acts as a negative regulator of TLR–IL‐1R signalling by interacting with TRAF6. This interaction prevented auto‐ubiquitination and oligomerization of TRAF6 and subsequently inhibited NF‐κB activation and pro‐inflammatory cytokine production. Taken together, our GWAS‐based analysis and in vitro and in vivo studies have demonstrated that Nur77 is an important regulator of TRAF6/TLR–IL‐1R‐initiated inflammatory signalling, and loss of Nur77 may contribute to the development of IBD, suggesting Nur77 as a potential target for the prevention and treatment of IBD. Copyright

RARγ Downregulation Contributes to Colorectal Tumorigenesis and Metastasis by Derepressing the Hippo–Yap Pathway

The Hippo-Yap pathway conveys oncogenic signals, but its regulation during cancer development is not well understood. Here, we identify the nuclear receptor RARγ as a regulator of the Hippo-Yap pathway in colorectal tumorigenesis and metastasis. RARγ is downregulated in human colorectal cancer tissues, where its expression correlates inversely with tumor size, TNM stage, and distant metastasis. Functional studies established that silencing of RARγ drove colorectal cancer cell growth, invasion, and metastatic properties both in vitro and in vivo Mechanistically, RARγ controlled Hippo-Yap signaling to inhibit colorectal cancer development, acting to promote phosphorylation and binding of Lats1 to its transcriptional coactivator Yap and thereby inactivating Yap target gene expression. In clinical specimens, RARγ expression correlated with overall survival outcomes and expression of critical Hippo-Yap pathway effector molecules in colorectal cancer patients. Collectively, our results defined RARγ as tumor suppressor in colorectal cancer that acts by restricting oncogenic signaling by the Hippo-Yap pathway, with potential implications for new approaches to colorectal cancer therapy. Cancer Res; 76(13); 3813-25. ©2016 AACR.

Nur77-mediated TRAF6 signalling protects against LPS-induced sepsis in mice

BackgroundNur77, a key member of the NR4A receptor subfamily, is involved in the regulation of inflammation and immunity. However, the in vivo regulatory roles of Nur77 in sepsis and the mechanisms involved remains largely elusive. In this study, we used Nur77-deficient (Nur77−/−) mice and investigated the function of Nur77 in sepsis.FindingsCompared to wild-type (Nur77+/+) mice, Nur77−/− mice are more susceptible to LPS-induced sepsis and acute liver inflammation. Mechanistically, we observed that Nur77 can interact with TRAF6, a crucial adaptor molecule in the Toll-like receptor-interleukin 1 receptor (TLR-IL-1R) signalling pathway, in in vivo mouse model of sepsis. The interaction may affect TRAF6 auto-ubiquitination, thereby inhibiting NF-κB activation and pro-inflammatory cytokines production.ConclusionsThese in vivo observations reveals an important protective role for Nur77 in LPS-induced sepsis through its regulation to TRAF6 signalling, and highlights the potential clinical application of Nur77 as a molecular target in prevention and/or treatment of sepsis.

Molecular cloning, organization, expression and 3D structural analysis of the MHC class Ia gene in the whitespotted bamboo shark (Chiloscyllium plagiosum)

Cartilaginous fishes are the oldest jawed vertebrates, from which the major histocompatibility complex (MHC) derived approximately 500 MYA; however, full-length genomic sequences for MHC genes in these species remain undescribed. This lack of basic information about MHC organization in cartilaginous fish is hindering investigations into the relationship between MHC polymorphism and disease, and leaves a large gap in our understanding of shark MHC evolution. Here, we obtained a complete 4887 bp genomic DNA of chplUAA (designated as chplUAA) from the whitespotted bamboo shark (Chiloscyllium plagiosum) using long PCR. The full-length cDNA sequence was 1385 bp, with a 1029 bp open reading frame (ORF) encoding 343 amino acids. Six unique sequences (chplUAA*01-06) were detected from 51 sequences from three samples. No more than two sequences were found in each individual, suggesting that only one UAA locus was amplified in each sample. Phylogenetic analysis supports monophyly of all available shark classical class Ia sequences.

Genetic variants in ERBB4 is associated with chronic hepatitis B virus infection

Background The role of ERBB4 in liver disease has seldom been reported. This study aims to find genetic markers at ERBB4 for chronic hepatitis B virus (HBV) infection and determine the role of ERBB4 in liver injury. Methods We selected and genotyped three single nucleotide polymorphisms and one insertion/deletion (Ins/Del) at the 5′ and 3′ untranslated region (UTR) of ERBB4 in a case-control study including 1344 pairs of HBV carriers and HBV natural clearance subjects. The luciferase reporter system was applied to study the regulative role of Ins/Del on ERBB4. Further, ERBB4 knockout mice were used to study the role of ERBB4 in liver injury. Proteomic quantification was performed by HPLC-MS/MS analysis to identify liver protein profile change between liver-specific ERBB4 knockout and control mice. Results rs6147150 Ins/Del and rs1836724 T>C at the 3′ UTR of ERBB4 were associated with reduced risk of chronic HBV infection (P = 0.002 and 0.004, respectively). Besides, the 12bp deletion at the 3′ UTR increased ERBB4 expression due to lacking let-7c binding site. In addition, loss of ERBB4 led to more severe acute or chronic inflammation in mouse liver injury models. Further, quantitative proteomic analysis and data from the cancer genome atlas revealed that ACLY, an enzyme key for de novo lipogenesis, was negatively correlated with ERBB4. Conclusions ERBB4 plays protective role from liver injury and its 3′UTR genetic variants could be genetic markers for chronic HBV infection.

The long non-coding RNA NONHSAT062994 inhibits colorectal cancer by inactivating Akt signaling

The aberrant expression of long noncoding RNAs (lncRNAs) is implicated in cancer development and progression. However, the clinical significance and mechanism by which NONHSAT062994 regulates colorectal cancer (CRC) is unknown. We here reported that NONHSAT062994 was significantly downregulated in human CRC tissues and cell lines. Moreover, its expression was inversely correlated with tumor size and overall survival (OS) time in CRC patients. In CRC cells, the overexpression and knockdown of NONHSAT062994 inhibited and enhanced CRC cell growth, respectively, in vitro and in vivo. Mechanistically, NONHSAT062994 functioned as a tumor suppressor to inhibit CRC cell growth by inactivating Akt signaling. Notably, the NONHSAT062994 expression status was negatively correlated with the Akt downstream targets c-Myc and Cyclin D1 in clinical CRC samples. The current findings suggest that NONHSAT062994 plays a critical role in the development of CRC by regulating Akt signaling, and identified a candidate prognostic biomarker or potential therapeutic target for CRC patients.

Nur77 deficiency in mice accelerates tumor invasion and metastasis by facilitating TNFα secretion and lowering CSF-1R expression

Nur77, an orphan member of the nuclear receptor superfamily, plays critical roles in inflammation and immunity. However, the role of Nur77 in tumor microenvironment remains elusive. Results showed that deletion of Nur77 strikingly enhanced tumor metastasis compared to WT mice. Additionally, compared to the conditioned media derived from Nur77+/+ peritoneal macrophages (CM1), the conditioned media derived from Nur77-/- peritoneal macrophages (CM2) significantly promoted the EMT of cancer cells, and greatly enhanced the migratory and invasive abilities of cancer cells. Moreover, studies using TNF-α blocking antibody demonstrated that pro-inflammatory cytokine TNF-α was indispensable in supporting CM2-induced EMT to drive cancer cells migration and invasion. Furthermore, we found that Nur77 promoted the expression of CSF-1R, a novel downstream target gene of Nur77, and subsequently enhanced the migration of inflammatory cells. Notably, infiltration of inflammatory cells in the tumors of Nur77-/- mice was markedly abrogated compared to Nur77+/+ mice. Collectively, these results revealed that host Nur77 expression was pivotal in antitumor immune response, and in inhibiting tumor metastasis.

Orphan nuclear receptor Nur77 inhibits poly (I:C)-triggered acute liver inflammation by inducing the ubiquitin-editing enzyme A20

Inflammation is a key contributor to various types of acute and chronic liver disease. We recently reported that lack of Nur77, an orphan nuclear receptor, contributes to the pathogenesis of inflammatory diseases including inflammatory bowel disease and sepsis. However, whether Nur77 plays a critical role in liver inflammation remains to be fully understood. Employing in vivo acute liver inflammation model in wild-type (Nur77+/+) and Nur77-/- mice, we here found that Nur77 deficiency dramatically increased the production of pro-inflammatory cytokines and accelerated liver injury induced by Poly (I:C)/D-GalN in Nur77-/- mice. Mechanistically, Nur77 acts as a negative regulator of NF-κB signaling by inducing the expression of ubiquitin-editing enzyme A20, a novel target gene of Nur77. Notably, in inflammatory cells, overexpression of A20 enhanced, whereas knockdown of A20 by siRNA approach impaired, the inhibitory effect of Nur77 on Poly (I:C)-triggered inflammation. Collectively, our data suggest that the orphan nuclear receptor Nur77 plays a protective role in Poly (I:C)-triggered liver inflammation by inducing A20, thus making it a promising target for the prevention and treatment of liver inflammation.Inflammation is a key contributor to various types of acute and chronic liver disease. We recently reported that lack of Nur77, an orphan nuclear receptor, contributes to the pathogenesis of inflammatory diseases including inflammatory bowel disease and sepsis. However, whether Nur77 plays a critical role in liver inflammation remains to be fully understood. Employing in vivo acute liver inflammation model in wild-type (Nur77+/+) and Nur77-/- mice, we here found that Nur77 deficiency dramatically increased the production of pro-inflammatory cytokines and accelerated liver injury induced by poly (I:C)/D-GalN in Nur77-/- mice. Mechanistically, Nur77 acts as a negative regulator of NF-κB signaling by inducing the expression of ubiquitin-editing enzyme A20, a novel target gene of Nur77. Notably, in inflammatory cells, overexpression of A20 enhanced, whereas knockdown of A20 by siRNA approach impaired, the inhibitory effect of Nur77 on poly (I:C)-triggered inflammation. Collectively, our data suggest that the orphan nuclear receptor Nur77 plays a protective role in poly (I:C)-triggered liver inflammation by inducing A20, thus making it a promising target for the prevention and treatment of liver inflammation.