HuB and HuD repress telomerase activity by dissociating HuR from TERC

The ubiquitous RNA-binding protein HuR (ELAVL1) promotes telomerase activity by associating with the telomerase noncoding RNA TERC. However, the role of the neural-specific members HuB, HuC, and HuD (ELAVL2–4) in telomerase activity is unknown. Here, we report that HuB and HuD, but not HuC, repress telomerase activity in human neuroblastoma cells. By associating with AU-rich sequences in TERC, HuB and HuD repressed the assembly of the TERT–TERC core complex. Furthermore, HuB and HuD competed with HuR for binding to TERC and antagonized the function of HuR that was previously shown to enhance telomerase activity to promote cell growth. Our findings reveal a novel mechanism controlling telomerase activity in human neuroblastoma cells that involves a competition between HuR and the related, neural-specific proteins HuB and HuD.     

Systematic evaluation,verification and comparison of tuberculosis-related non-coding RNA diagnostic panels

We systematically summarized tuberculosis (TB)-related non-coding RNA (ncRNA) diagnostic panels, validated and compared panel performance. We searched TB-related ncRNA panels in PubMed, OVID and Web of Science up to 28 February 2020, and available datasets in GEO, SRA and EBI ArrayExpress up to 1 March 2020. We rebuilt models and synthesized the results of each model in validation sets by bivariate mixed models. Specificity at 90% sensitivity, area under curve (AUC) and inconsistence index (I²) were calculated. NcRNA biofunctions were analysed. Nineteen models based on 18 ncRNA panels (miRNA, lncRNA, circRNA and snoRNA panels) and 18 datasets were included. Limited available datasets only allowed to evaluate miRNA panels further. Cui 2017 and Latorre 2015 exhibited specificity >70% at 90% sensitivity and AUC >80% in all validation sets. Cui 2017 showed higher specificity at 90% sensitivity (92%) and AUC (95%) and lower heterogeneity (I² = 0%) in ethological-confirmation validation sets. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that most ncRNAs in panels involved in immune cell activation, oxidative stress, and Wnt and MAPK signalling pathway. Cui 2017 outperformed other models in both all available and aetiological-confirmed validation sets, meeting the criteria of target product profile of WHO. This work provided a basis for clinical choice of TB-related ncRNA diagnostic panels to a certain extent.     

Early-life gut microbiome and cow’s milk allergy- a prospective case - control 6-month follow-up study

Increasing evidence suggests that perturbations in the intestinal microbiota in early infancy are implicated in the pathogenesis of food allergy (FA); existing evidence on the structure and composition of the intestinal microbiota in human beings with FA is limited and conflicting. The main object of the study was to compare the faecal microbiota between healthy and cow’s milk allergy (CMA) infants at the baseline immediately after the diagnosis, and to evaluate the changes in the faecal microbiota after 6?months of treatment of CMA infants with hypoallergenic formula (HF), compared with healthy children fed on standard milk formulae. Sixty infants younger than 4?months of age with challenge-proven CMA and 60 healthy age-matched children were investigated in this prospective case - control follow-up study. Faecal samples were collected at baseline and at 6?months of follow-up, microbial diversity and composition were characterized by high-throughput 16S rRNA sequencing. The average age (±SD) of the infants at inclusion was 2.9?±?1.0?months. Children with CMA have lower gut microbiota diversity and an elevated Enterobacteriaceae to Bacteroidaceae (E/B ratio) in early infancy compared with healthy children (115.8 vs. 0.8, P?=?0.0002). After 6?months of treatment with HF, CMA infants had a higher Lactobacillaceae (6.3% vs. 0.5%, P?=?0.04) and lower Bifidobacteriaceae (0.3% vs. 8.2%, P?=?0.03) and Ruminococcaceae (1.5% vs. 10.5%, P?=?0.03) abundance compared with control children. Conclusion: Low gut microbiota diversity and an elevated E/B ratio in early infancy may contribute to the development of FA, including CMA. A strict elimination diet may weaken FA by reducing E/B ratio and promoting a gut microbiota that would benefit the acquisition of oral tolerance.     

Newly identified proviruses in Thermotogota suggest that viruses are the vehicles on the highways of interphylum gene sharing

Phylogenomic analyses of bacteria from the phylum Thermotogota have shown extensive lateral gene transfer with distantly related organisms, particularly with Firmicutes. One likely mechanism of such DNA transfer is viruses. However, to date, only three temperate viruses have been characterized in this phylum, all infecting bacteria from the Marinitoga genus. Here we report 17 proviruses integrated into genomes of bacteria belonging to eight Thermotogota genera and induce viral particle production from one of the proviruses. All except an incomplete provirus from Mesotoga fall into two groups based on sequence similarity, gene synteny and taxonomic classification. Proviruses of Group 1 are found in the genera Geotoga, Kosmotoga, Marinitoga, Thermosipho and Mesoaciditoga and are similar to the previously characterized Marinitoga viruses, while proviruses from Group 2 are distantly related to the Group 1 proviruses, have different genome organization and are found in Petrotoga and Defluviitoga. Genes carried by both groups are closely related to Firmicutes and Firmicutes (pro)viruses in phylogenetic analyses. Moreover, one of the groups show evidence of recent gene exchange and may be capable of infecting cells from both phyla. We hypothesize that viruses are responsible for a large portion of the observed gene flow between Firmicutes and Thermotogota.     

Synergistic anticancer effects of lectin and doxorubicin in breast cancer cells

We studied the effects, either combined or alone, of lectin from Korean mistletoe (Viscum album var. coloratum agglutinin, VCA) and doxorubicin (DOX) in MCF-7 (estrogen receptor-positive) and MDA-MB231 (estrogen receptor-negative) human breast cancer cells. When VCA and DOX were combined, a strong synergistic effect was shown in cell growth inhibition, compared to VCA or DOX treatment alone. In quantitative apoptosis studies analyzed by flow cytometry, a combination of two agents showed an increase in apoptosis in both cells, compared to agents alone. Also, pro-apoptotic proteins including Bax, Bik, and Puma were increased in both cells, and the survival factor Bcl-2 was inhibited in MCF-7 cells when drugs were combined. Furthermore, VCA combined with DOX mediated S phase arrest, accompanied with a decrease of cell number at G0/G1 phase. This suggests that VCA and DOX combination may possibly lead to a novel strategy for the treatment of breast cancer.     

Structural and biochemical characterization of a multidomain alginate lyase reveals a novel role of CBM32 in CAZymes

Noncatalytic carbohydrate binding modules (CBMs) have been demonstrated to play various roles with cognate catalytic domains. However, for polysaccharide lyases (PLs), the roles of CBMs remain mostly unknown. AlyB is a multidomain alginate lyase that contains CBM32 and a PL7 catalytic domain. The AlyB structure determined herein reveals a noncanonical alpha helix linker between CBM32 and the catalytic domain. More interestingly, CBM32 and the linker does not significantly enhance the catalytic activity but rather specifies that trisaccharides are predominant in the degradation products. Detailed mutagenesis, biochemical and cocrystallization analyses show “weak but important” CBM32 interactions with alginate oligosaccharides. In combination with molecular modeling, we propose that the CBM32 domain serves as a “pivot point” during the trisaccharide release process. Collectively, this work demonstrates a novel role of CBMs in the activity of the appended PL domain and provides a new avenue for the well-defined generation of alginate oligosaccharides by taking advantage of associated CBMs.     

Long-term nitrogen deposition inhibits soil priming effects by enhancing phosphorus limitation in a subtropical forest

It is widely accepted that phosphorus (P) limits microbial metabolic processes and thus soil organic carbon (SOC) decomposition in tropical forests. Global change factors like elevated atmospheric nitrogen (N) deposition can enhance P limitation, raising concerns about the fate of SOC. However, how elevated N deposition affects the soil priming effect (PE) (i.e., fresh C inputs induced changes in SOC decomposition) in tropical forests remains unclear. We incubated soils exposed to 9 years of experimental N deposition in a subtropical evergreen broadleaved forest with two types of ¹³C-labeled substrates of contrasting bioavailability (glucose and cellulose) with and without P amendments. We found that N deposition decreased soil total P and microbial biomass P, suggesting enhanced P limitation. In P unamended soils, N deposition significantly inhibited the PE. In contrast, adding P significantly increased the PE under N deposition and by a larger extent for the PE of cellulose (PE_cellu) than the PE of glucose (PE_glu). Relative to adding glucose or cellulose solely, adding P with glucose alleviated the suppression of soil microbial biomass and C-acquiring enzymes induced by N deposition, whereas adding P with cellulose attenuated the stimulation of acid phosphatase (AP) induced by N deposition. Across treatments, the PE_glu increased as C-acquiring enzyme activity increased, whereas the PE_cellu increased as AP activity decreased. This suggests that P limitation, enhanced by N deposition, inhibits the soil PE through varying mechanisms depending on substrate bioavailability; that is, P limitation regulates the PE_glu by affecting soil microbial growth and investment in C acquisition, whereas regulates the PE_cellu by affecting microbial investment in P acquisition. These findings provide new insights for tropical forests impacted by N loading, suggesting that expected changes in C quality and P limitation can affect the long-term regulation of the soil PE.     

Synergistic protective effect of paeoniflorin and β-ecdysterone against rotenone-induced neurotoxicity in PC12 cells

There are several factors, like oxidative stress and neurons loss, involving neurodegenerative diseases such as Parkinson’s disease (PD). The combination of antioxidant and anti-apoptotic agent is becoming a promising approach to fight against PD. This study evaluates the hypothesis that paeoniflorin (PF) and β-ecdysterone (β-Ecd) synergize to protect PC12 cells against toxicity induced by PD-related neurotoxin rotenone. The combination of PF and β-Ecd, hereafter referred to as the PF/β-Ecd, at suboptimal concentrations increased the viability of rotenone-exposed PC12 cells in a synergistic manner. PF and β-Ecd cooperate to attenuate the rotenone-induced apoptosis by decrease in Bax expression, caspase-9 activity, and caspase-3 activity. PF or PF/β-Ecd, but not β-Ecd, inhibited rotenone-triggered protein kinase C-δkinase C-δ (PKCδ) upregulation and nuclear factor κB (NF-κB) activation. β-Ecd or PF/β-Ecd, but not PF, enhanced serine/threonine protein kinase (Akt) activation, promoted nuclear factor E2-related factor 2 (Nrf2) nuclear accumulation, suppressed reactive oxygen species (ROS) production. Neuroprotection of PF/β-Ecd could be completely blocked by PKCδ inhibitor rottlerin plus Akt specific inhibitor LY294002. Dual blockade of the PKCδ/NF-κB pathway by PF and activation of Akt/Nrf2 pathway by β-Ecd results in a synergistic neuroprotective effect against rotenone-induced neurotoxicity in vitro. These findings provide the rationale for determining the in vivo activity of combined therapy with PF and β-Ecd against PD.