Gluconeogenesis, an essential metabolic process for hepatocytes, is downregulated in hepatocellular carcinoma (HCC). Here we show that the nuclear receptor Nur77 is a tumour suppressor for HCC that regulates gluconeogenesis. Low Nur77 expression in clinical HCC samples correlates with poor prognosis, and a Nur77 deficiency in mice promotes HCC development. Nur77 interacts with phosphoenolpyruvate carboxykinase (PEPCK1), the rate-limiting enzyme in gluconeogenesis, to increase gluconeogenesis and suppress glycolysis, resulting in ATP depletion and cell growth arrest. However, PEPCK1 becomes labile after sumoylation and is degraded via ubiquitination, which is augmented by the p300 acetylation of ubiquitin-conjugating enzyme 9 (Ubc9). Although Nur77 attenuates sumoylation and stabilizes PEPCK1 via impairing p300 activity and preventing the Ubc9-PEPCK1 interaction, Nur77 is silenced in HCC samples due to Snail-mediated DNA methylation of the Nur77 promoter. Our study reveals a unique mechanism to suppress HCC by switching from glycolysis to gluconeogenesis through Nur77 antagonism of PEPCK1 degradation.

MicroRNAs play crucial roles in tumorigenesis and tumor progression. miR-770 has been reported to be downregulated in several cancers and affects cancer cell proliferation, apoptosis, metastasis and drug resistance. However, the role and underlying molecular mechanism of miR-770 in human glioma remain unknown and need to be further elucidated.

Thymosin β4 (Tβ4) is the most abundant member of the β-thymosins and plays an important role in the control of actin polymerization in eukaryotic cells. While its effects in multiple organs and diseases are being widely investigated, the safety profile has been established in animals and humans, currently, little is known about its influence on Alzheimer's disease (AD) and the possible mechanisms. Thus, we aimed to evaluate the effects and mechanisms of Tβ4 on glial polarization and cognitive performance in APP/PS1 transgenic mice.

Pulmonary fibrosis is a typical sequela of coronavirus disease 2019 (COVID-19), which is linked with a poor prognosis for COVID-19 patients. However, the underlying mechanism of pulmonary fibrosis induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. Here, we demonstrated that the nucleocapsid (N) protein of SARS-CoV-2 induced pulmonary fibrosis by activating pulmonary fibroblasts. N protein interacted with the transforming growth factor β receptor I (TβRI), to disrupt the interaction of TβRI-FK506 Binding Protein12 (FKBP12), which led to activation of TβRI to phosphorylate Smad3 and boost expression of pro-fibrotic genes and secretion of cytokines to promote pulmonary fibrosis. Furthermore, we identified a compound, RMY-205, that bound to Smad3 to disrupt TβRI-induced Smad3 activation. The therapeutic potential of RMY-205 was strengthened in mouse models of N protein-induced pulmonary fibrosis. This study highlights a signaling pathway of pulmonary fibrosis induced by N protein and demonstrates a novel therapeutic strategy for treating pulmonary fibrosis by a compound targeting Smad3.

In animal models with temporal lobe epilepsy (TLE), the status epilepticus (SE) leads to a dramatic increase in number of newly born neuron in the subgranular zone (SGZ) of dentate gyrus. How the SE confers a modulation in the dentate neurogenesis is mostly unknown. Gadd45b is involved in epigenetic gene activation by DNA demethylation. This study was performed to present a novel mechanism underling SE-induced dentate neurogenesis. A transient induction (12 hrs to 3 days) of Gadd45b was observed in dentate gyrus of mice after pilocarpine-induced SE. Labeling the dividing cells with BrdU, we next found that the induction of Gadd45b was required to increase the rate of cell proliferation in the dentate gyrus at 7 and 14 days after SE. Afterward, the DNA methylation levels for candidate growth factor genes critical for the adult neurogenesis were assayed with Sequenom MassARRAY Analyzer. The results indicated that Gadd45b was necessary for SE-induced DNA demethylation of specific promoters and expression of corresponding genes in the dentate gyrus, including brain-derived neurotrophic factor (BDNF) and fibroblast growth factor-2 (FGF-2). Using Timm staining, we further suggested that SE-induced Gadd45b might contribute to the subsequent mossy fiber sprouting (MFS) in the chronically epileptic hippocampus via epigenetic regulation of dentate neurogenesis at early stage after SE. Together, Gadd45b links pilocarpine-induced SE to epigenetic DNA modification of secreted factors in the dentate gyrus, leading to extrinsic modulation on the neurogenesis.

Recent animal studies showed that isoflurane exposure may lead to the disturbance of hippocampal neurogenesis and later cognitive impairment. However, much less is known about the effect of isoflurane exposure on the neurons generated form tertiary dentate matrix, even though a great increase of granule cell population during the infantile period is principally derived from this area.

Fatty acid oxidation (FAO) is crucial for cells to overcome metabolic stress by providing ATP and NADPH. However, the mechanism by which FAO is regulated in tumors remains elusive. Here we show that Nur77 is required for the metabolic adaptation of melanoma cells by protecting FAO. Glucose deprivation activates ERK2 to phosphorylate and induce Nur77 translocation to the mitochondria, where Nur77 binds to TPβ, a rate-limiting enzyme in FAO. Although TPβ activity is normally inhibited by oxidation under glucose deprivation, the Nur77-TPβ association results in Nur77 self-sacrifice to protect TPβ from oxidation. FAO is therefore able to maintain NADPH and ATP levels and prevent ROS increase and cell death. The Nur77-TPβ interaction further promotes melanoma metastasis by facilitating circulating melanoma cell survival. This study demonstrates a novel regulatory function of Nur77 with linkage of the FAO-NADPH-ROS pathway during metabolic stress, suggesting Nur77 as a potential therapeutic target in melanoma.