Importin ß1 mediates nuclear import of the factors associated with nonsense-mediated RNA decay.

In eukaryotic cells, nonsense-mediated RNA decay (NMD) is an essential physiological mechanism coupled to translation, regulating the stability of abnormal RNA containing premature termination codon (PTC) and a significant fraction of normal transcriptomes. So far, the molecular regulation mechanism of NMD pathway is far from fully elucidated. Previously, we observed the interaction between importin ß1 (Impß1) and UPF1, a core factor of NMD. Here, we demonstrated that Impß1 knockdown stabilized NMD reporters, and Impß1 and UPF1 interacted and co-regulated an extensive number of target transcripts. Furthermore, Impß1 affected the interaction between UPF1 and SMG5 or MAGOH, and the nuclear distributions of UPF1, SMG1, SMG5 and MAGOH. Besides, Ran knockdown extremely promoted the dissociation of UPF1 from SMG5 or MAGOH. Our findings provide molecular insight into the potential function of Impß1in nonsense-mediated RNA decay.

Baicalein enhanced cisplatin sensitivity of gastric cancer cells by inducing cell apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway.

Baicalein is a natural flavonoid with various pharmacological activities including antitumor. The synergistic anti-cancer effect of the combination of baicalein and Cisplatin (DDP) on gastric cancer (GC) has not been reported. MTT assay and colony formation assay were used to determine the inhibitory effect of the combination of baicalein and DDP on cell survival. Invasive assay was performed to test the effects of baicalein and DDP on cell invasive capability. A flow cytometric analysis was conducted to determine the apoptosis-induced effects of baicalein on GC cells, especially SGC-7901/DDP (resistant to DDP). Confocal laser microscope and real-time PCR were used to test autophagy-induced effects of baicalein on SGC-7901 and SGC-7901/DDP cells. Western blotting was performed to investigate the molecular mechanisms of baicalein inducing apoptosis and autophagy. Our study showed that baicalein could inhibit cell proliferation of MGC-803, HGC-27, SGC-7901 and SGC-7901/DDP, and the inhibitory effect was extremely enhanced when combining with DDP. Additionally, combination of baicalein and DDP suppressed the invasive capability and induced apoptosis and autophagy in both SGC-7901 and SGC-7901/DDP, and the effect was stronger than that of DDP or baicalein alone. The further molecular mechanism analysis indicated that baicalein modulated the activities of Akt/mTOR and Nrf2/Keap 1 signaling. Our study demonstrated that baicalein enhanced DDP sensitivity of SGC-7901/DDP gastric cancer cells by inducing apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway.

Down expression of LRP1B promotes cell migration via RhoA/Cdc42 pathway and actin cytoskeleton remodeling in renal cell cancer.

The low-density lipoprotein receptor-related protein 1B (LRP1B) is known as a putative tumor suppressor. The decreased expression of LRP1B has been involved in multiple primary cancers in several studies. However, its expression and function in the carcinogenesis of renal cell cancer (RCC) remain unclear. In this study, we investigated the expression of LRP1B in RCC by in situ hybridization (ISH) and real-time polymerase chain reaction (qRT-PCR). Our results indicated that LRP1B was frequently downexpressed in human RCC tissue and cell lines, which involved both epigenetic events (DNA methylation and histone deacetylation) and N-terminal deletion of LRP1B. Moreover, we testified that knockdown of LRP1B by shRNA significantly promoted anchorage-independent growth, cell migration and invasion in HEK293 cells and renal cancer cells 127 in vitro. We further found that silencing of LRP1B altered the expression of focal adhesion complex-associated proteins, and Cdc42/RhoA activities, which regulate the cytoskeleton dynamics. Taken together, these results strongly support that LRP1B may function as a tumor suppressor against renal cell cancer, and may regulate cell motility via RhoA/Cdc42 pathway and actin cytoskeleton reorganization in RCC.

Integrated analysis of metabolomic and transcriptomic profiling reveals the effect of Buyang Huanwu decoction on Parkinson's disease in mice.

BACKGROUND: Parkinson's disease (PD) is a common, complex, and chronic neurodegenerative disorder involved in multi-system. At present, medicine for PD has many limitations. Buyang Huanwu decoction (BHD), a famous traditional Chinese medicinal (TCM) formulae, is used in the treatment of PD clinically in China. However, the therapeutic mechanism is still unknown. PURPOSE: We aimed to explore the pharmacological mechanism of BHD alleviating PD through an integrated liver metabolome and brain transcriptome analysis. METHODS: The mice with PD were induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Behavioral tests and immunohistochemistry were used to evaluate the neuroprotective effects of BHD. The non-targeted metabolomics analysis was conducted to profile differentially accumulated metabolites (DAMs) in the liver using a UHPLC-Q-Exactive MS/MS method. The differentially expressed genes (DEGs) in the brain were investigated by transcriptomic analysis on an Illumina sequencing platform. The correlations of DAMs and DEGs were investigated using an integrated metabolomic and transcriptomic approach. RESULTS: The results of behavioral tests and immunohistochemistry proved the alleviated effects of BHD on PD symptoms. A total of 14 and 36 DAMs were detected in the groups treated with low- (L group) and high-dose (H group) BHD respectively under the positive ion mode. Compared with the PD model group (M group), three enriched pathways including metabolic pathways, ABC transporters, and biosynthesis of amino acids were common in the L and H group. Transcriptomic analysis proved that BHD could regulate the expression of numerous genes, some of which were targeted by Ben-Ldopa such as Creb5, Gm45623, Ccer2, Cd180, Fosl2, Crip3, and Noxred1. Based on the integrated metabolomic and transcriptomic analysis, 7 metabolite-gene pairs were found in four comparisons, including C vs M, M vs P, M vs L, and M vs H, and 6 enriched pathways containing purine metabolism, glycine/serine/threonine metabolism, phenylalanine metabolism, carbon fixation in photosynthetic organisms, thiamine metabolism, and ABC transporters were overlapped. CONCLUSIONS: Though the underlying pharmacological mechanism of BHD is still lacking, we provided evidence that BHD could improve dopaminergic neurons in MPTP-induced PD mice by regulating liver metabolism and brain transcriptome. The correlation between the liver and the brain was preliminarily revealed in this study.

MARVELD1 inhibited cell proliferation and enhance chemosensitivity via increasing expression of p53 and p16 in hepatocellular carcinoma.

We have previously found that expression of MARVELD1 was remarkably downregulated in multiple tumor tissues, but unclear in hepatocellular carcinoma (HCC) and its function has not been explored yet. In the present study, to uncover the underlying mechanism of MARVELD1 in the pathogenesis and development of HCC, we investigated the expression pattern of MARVELD1 and its effect on tumor proliferation in HCC. The results indicated the frequent downregulation of MARVELD1 in clinic samples and cell lines of HCC resulted from promoter methylation, as well as genetic deletion. Furthermore, treatment of MARVELD1 unexpressing Hep3B2.1-7 and PLC/PRF/5 cells with the demethylating agent 5-aza-2' deoxycytidine restored its expression. Overexpression of MARVELD1 suppressed the proliferation of HCC cells in vitro and in vivo, whereas downregulation of endogenous MARVELD1 by shRNAs significantly enhanced these characters. MARVELD1 overexpression could enhance chemosensitivity of HCC cells to epirubicin and 10-hydroxycamptothecin. Corresponding to these results, the expression of p-ERK1/2 and cyclin D1 were decreased, whereas p16 and p53 were increased in MARVELD1-transfected cells. We also demonstrated that knockdown of MARVELD1 resulted in upregulation of p-ERK1/2 and cyclin D1, and downregulation of p16 and p53. Moreover, the effect of the decreased cell growth rate was significantly reversed when MARVELD1-overexpressing cells were trasfected with p53 or p16 siRNA. Our findings suggest that MARVELD1 is a tumor suppressor by negatively regulating proliferation, tumor growth and chemosensitivity of HCC cells via increasing p53 and p16 in vitro and in vivo. MARVELD1 may be a potential target for HCC therapy.

Multi-Omics Reveals Inhibitory Effect of Baicalein on Non-Alcoholic Fatty Liver Disease in Mice.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, whose etiology is poorly understood. Accumulating evidence indicates that gut microbiota plays an important role in the occurrence and progression of various human diseases, including NAFLD. In this study, NAFLD mouse models were established by feeding a high-fat diet (HFD). Baicalein, a natural flavonoid with multiple biological activities, was administered by gavage, and its protective effect on NAFLD was analyzed by histopathological and blood factor analysis. Gut microbiota analysis demonstrated that baicalein could remodel the overall structure of the gut microbiota from NAFLD model mice, especially Anaerotruncus, Lachnoclostridium, and Mucispirillum. Transcriptomic analysis showed baicalein restored the expressions of numerous genes that were upregulated in hepatocytes of NAFLD mice, such as Apoa4, Pla2g12a, Elovl7, Slc27a4, Hilpda, Fabp4, Vldlr, Gpld1, and Apom. Metabolomics analysis proved that baicalein mainly regulated the processes associated with lipid metabolism, such as alpha-Linolenic acid, 2-Oxocarboxylic acid, Pantothenate and CoA biosynthesis, and bile secretion. Multi-omics analysis revealed that numerous genes regulated by baicalein were significantly correlated with pathways related to lipid metabolism and biosynthesis and secrection of bile acid, and baicalein might affect lipid metabolism in liver via regulating the ecological structure of gut microbiota in NAFLD mice. Our results elucidated the correlated network among diet, gut microbiota, metabolomic, and transcriptional profiling in the liver. This knowledge may help explore novel therapeutic approaches against NAFLD.

Effects and Mechanisms of Saikosaponin D Improving the Sensitivity of Human Gastric Cancer Cells to Cisplatin.

Gastric cancer (GC) is the second leading cause of cancer deaths around the world. Chemoresistance is an important reason for poor prognosis of GC. Saikosaponin D (SSD) is a natural constituent from Radix Bupleuri and exhibits various activities including antitumors. This study investigated the effects and the mechanisms of SSD on cisplatin (cis-diamminedichloroplatinum, DDP) sensitivity of GC cells. Findings suggested that SSD could promote the inhibitory effect of DDP on proliferation and invasion and increase DDP-induced apoptosis in SGC-7901 and DDP-resistant cell line SGC-7901/DDP. We further identified that SSD increased levels of LC3 B and cleaved caspase 3 and decreased levels of p62, IKK ß, p-IκB α, and NF-κB p65, suggesting that SSD might inhibit the IKK ß/NF-κB pathway and induce both cell autophagy and apoptosis in SGC-7901 and SGC-7901/DDP. A further study indicated that SSD enhanced the effect of DDP-induced cleaved caspase 3 level rise and NF-κB pathway suppression, especially in SGC-7901/DDP cells. Conclusively, SSD enhanced DDP sensitivity of GC cells; the potential molecular mechanisms were that SSD-induced apoptosis and autophagy and inhibited the IKK ß/NF-κB pathway in GC cells. These findings suggested that SSD might contribute to overcoming DDP resistance in GC treatment.

MARVELD1 Inhibits Nonsense-Mediated RNA Decay by Repressing Serine Phosphorylation of UPF1.

We have observed low expression levels of MARVELD1, a novel tumor repressor, in multiple tumors; however, its function in normal cells has not been explored. We recently reported that MARVELD1 interacts with importin ß1, which plays an important role in nonsense-mediated RNA decay(NMD). Here, we demonstrate that MARVELD1 substantially inhibits nonsense-mediated RNA decay by decreasing the pioneer round of translation but not steady-state translation, and we identify MARVELD1 as an important component of the molecular machinery containing UPF1 and Y14. Furthermore, we determined the specific regions of MARVELD1 and UPF1 responsible for their interaction. We also showed that MARVELD1 promotes the dissociation of SMG1 from UPF1, resulting in the repression of serine phosphorylation of UPF1, and subsequently blocks the recruitment of SMG5, which is required for ensuing SMG5-mediated exonucleolytic decay. Our observations provide molecular insight into the potential function of MARVELD1 in nonsense-mediated RNA decay.

MARVELD1 regulates integrin ß1-mediated cell adhesion and actin organization via inhibiting its pre-mRNA processing.

Cell adhesion on an extracellular matrix (ECM) participates in cell motility, invasion, cell signal transduction and gene expression. Many nuclear proteins regulate cell-ECM adhesion through managing the transcription of cell adhesion-related genes. Here, we identified MARVEL [MAL (The myelin and lymphocyte protein) and related proteins for vesicle trafficking and membrane link] domain containing 1 (MARVELD1) that could suppress cell spreading and complicate actin organization. Over-expression of MARVELD1 in NIH3T3 cells decreased the expression level of integrin ß1 and vinculin, and further led to dephosphorylation of focal adhesion kinase (FAK) at Tyr 397. We also found that MARVELD1 partially colocalized with serine/arginine-rich splicing factor 2 (SC35) and interacted with nuclear cap binding protein subunit 2 (CBP20). Finally, we demonstrated that pre-mRNA processing of integrin ß1 was affected by MARVELD1. Taken together, our studies demonstrate that MARVELD1 plays a role in pre-mRNA processing of integrin ß1, and thereby regulates cell adhesion and cell motility. These studies provide a novel regulatory mechanism of cell-ECM adhesion by nuclear protein in cells.

Identification and characterization of MARVELD1, a novel nuclear protein that is down-regulated in multiple cancers and silenced by DNA methylation.

MARVELD1 (MARVEL domain-containing 1) is a member of MARVEL domain-containing proteins and located on human chromosome 10q24.2. MARVELD1 has no significant similarity with other members of MARVEL domain family at amino acid level. Gene expression arrays demonstrated that MARVELD1 is widely expressed in normal human tissues and is down-regulated in primary multiple tumors derived from ovary, vulva, uterus, cervix, breast, testis, kidney, bladder and liver. The down-regulation of MARVELD1 was further identified by real-time PCR and immunohistochemical staining in primary breast cancer. In addition, we identified the reduced expression of MARVELD1 is owing to DNA methylation and could be reversed by pharmacologic demethylation. Finally, our results showed that MARVELD1 protein is located in nucleus instead of cell membrane.