Rett syndrome linked to defects in forming the MeCP2/Rbfox/LASR complex in mouse models.

Rett syndrome (RTT) is a severe neurological disorder and a leading cause of intellectual disability in young females. RTT is mainly caused by mutations found in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). Despite extensive studies, the molecular mechanism underlying RTT pathogenesis is still poorly understood. Here, we report MeCP2 as a key subunit of a higher-order multiunit protein complex Rbfox/LASR. Defective MeCP2 in RTT mouse models disrupts the assembly of the MeCP2/Rbfox/LASR complex, leading to reduced binding of Rbfox proteins to target pre-mRNAs and aberrant splicing of Nrxns and Nlgn1 critical for synaptic plasticity. We further show that MeCP2 disease mutants display defective condensate properties and fail to promote phase-separated condensates with Rbfox proteins in vitro and in cultured cells. These data link an impaired function of MeCP2 with disease mutation in splicing control to its defective properties in mediating the higher-order assembly of the MeCP2/Rbfox/LASR complex.

QKI-5 regulates the alternative splicing of cytoskeletal gene ADD3 in lung cancer.

Accumulating evidence indicates that the alternative splicing program undergoes extensive changes during cancer development and progression. The RNA-binding protein QKI-5 is frequently downregulated and exhibits anti-tumor activity in lung cancer. Howeve-r, little is known about the functional targets and regulatory mechanism of QKI-5. Here, we report that upregulation of exon 14 inclusion of cytoskeletal gene Adducin 3 (ADD3) significantly correlates with a poor prognosis in lung cancer. QKI-5 inhibits cell proliferation and migration in part through suppressing the splicing of ADD3 exon 14. Through genome-wide mapping of QKI-5 binding sites in vivo at nucleotide resolution by iCLIP-seq analysis, we found that QKI-5 regulates alternative splicing of its target mRNAs in a binding position-dependent manner. By binding to multiple sites in an upstream intron region, QKI-5 represses the splicing of ADD3 exon 14. We also identified several QKI mutations in tumors, which cause dysregulation of the splicing of QKI targets ADD3 and NUMB. Taken together, our results reveal that QKI-mediated alternative splicing of ADD3 is a key lung cancer-associated splicing event, which underlies in part the tumor suppressor function of QKI.

Effects of extraction methods on immunology activity and chemical profiles of Lycium barbarum polysaccharides.

It has been proven that polysaccharides have bioactivities and are beneficial to cure many diseases. Lycium barbarum fruit is widely used as a functional food all over the world, which main active component is L. barbarum polysaccharides (LBPs). In this study, classical hot water extraction (HWE), microwave assisted extraction (MAE), ultrasonic assisted extraction (UAE) and pressurized liquid extraction (PLE) were used to extracted LBP. The chemical properties of LBPs were evaluated in terms of total polysaccharide contents, uronic acid contents and protein contents. High performance size exclusion chromatography coupled with multi angle laser light scattering and refractive index detector was applied to measure the characters such as molecular weight, radius of gyration and polydispersity index. Then the immunomodulatory activity of LBPs was evaluated through RAW 264.7 cells. The results showed that HWE was the best method to get the highest total sugar and acidic polysaccharides, MAE was preferable to extract polysaccharide-protein complex, but PLE, UAE and HWE could get better immunomodulatory activity polysaccharides than MAE. Besides, the peak 3 in chromatogram of MAE extracted LBPs was obviously higher than those of LBPs produced by other 3 extraction methods, which suggested that peak 1 and peak 2 might be biologically active polysaccharides fractions in LBPs. Therefore, effect of different extraction methods on structure and composition of LBPs attributed to their variance of immunological activities.

2-O-ß-d-glucopyranosyl-l-ascorbic acid, a novel vitamin C derivative from Lycium barbarum, prevents oxidative stress.

Reducing agents are crucial for the management of maladaptive inflammation-induced macrophage death and hematopoietic toxicity of chemotherapy. 2-O-ß-d-glucopyranosyl-l-ascorbic acid (AA-2ßG), a unique AA (or vitamin C) derivative identified in Lycium barbarum, exhibited enhanced free radical scavenging activity compared with AA and its synthetic derivative AA-2αG. AA-2ßG protected hydrogen peroxide-induced cell death in murine macrophage RAW264.7 cells. Treatment with AA-2ßG eliminated oxidative stress and the ratio of cellular glutathione to glutathione disulfide more effectively than AA and AA-2αG. AA-2ßG also significantly reduced the fluorescent intensity of DCFH-DA triggered by chemotherapeutic agent camptotehcin-11 but not fluorouracil. AA, AA-2αG, and AA-2ßG significantly decreased Keap-1expression, and increased the expression levels of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1. All compounds triggered the nuclear translocation of Nrf2, while the ability of AA-2ßG to enhance the Nrf2-DNA binding affinity was approximately two fold as those of AA and AA-2αG. Sodium ascorbate cotransporters (SVCT) inhibitors, sulfinpyrazone, phloretin, and 3-O-methyglucose, potently abrogated the free radical scavenging activities of AA, AA-2αG, and AA-2ßG. The cellular uptake efficacy of AA-2αG and AA-2ßG was less than 10% of AA, while the inhibition of SVCT with sulfinpyrazone considerably diminished the uptake efficacy of these compounds. AA-2αG and AA-2ßG are more stable in the Fenton reagents than AA. In summary, AA-2ßG from L. barbarum with excellent free radical scavenging activity is a promising natural AA derivative for further pharmacological evaluation.

Lanostane triterpenes from the mushroom Ganoderma resinaceum and their inhibitory activities against α-glucosidase.

Eighteen previously undescribed lanostane triterpenes and thirty known analogues were obtained from the fruiting bodies of Ganoderma resinaceum. Resinacein C was isolated from a natural source for the first time. The structures of all the above compounds were elucidated by extensive spectroscopic analysis and comparisons of their spectroscopic data with those reported in the literature. Furthermore, in an in vitro assay, Resinacein C, ganoderic acid Y, lucialdehyde C, 7-oxo-ganoderic acid Z3, 7-oxo-ganoderic acid Z, and lucidadiol showed strong inhibitory effects against α-glucosidase compared with the positive control drug acarbose. The structure-activity relationships of ganoderma triterpenes on α-glucosidase inhibition showed that the C-24/C-25 double bond is necessary for α-glucosidase inhibitory activity. Moreover, the carboxylic acid group at C-26 and the hydroxy group at C-15 play important roles in enhancing inhibitory effects of these triterpenes.