Role of miR-181b/Notch1 Axis in circ_TNPO1 Promotion of Proliferation and Migration of Atherosclerotic Vascular Smooth Muscle Cells.

Background: The role and expression level change in circ_TNPO1 (hsa_circ_0072951) in atherosclerosis (AS) and VSMC dysfunction remain unknown. In this study, we try to explore the effects of circ_TNPO1 on oxidized low-density lipoprotein (ox-LDL)-induced human vascular smooth muscle cell (VSMC) excessive proliferation and migration, and the potential molecular mechanism. Methods: Quantitative real-time polymerase chain reaction (RT-qPCR) and western blot experiment were used to detect the serum samples from AS patients and healthy controls. CCK-8, Transwell, and the dual-luciferase reporter gene assay were used to detect the cell biology. Results: In human AS serum and ox-LDL-induced VSMCs, circ_TNPO1 was increased, whereas miR-181b was decreased. Silencing circ_TNPO1 inhibited proliferation and migration activity and reduced protein expression of PCNA, Ki-67, MMP2, and E-cadherin and promoted N-cadherin protein expression in ox-LDL induced VSMCs. Remarkably, miR-181b knockdown or Notch1 overexpression could efficiently offset the proliferation and migration inhibiting effect of circ_TNPO1 knockdown in ox-LDL-induced VSMCs. Furthermore, a molecular mechanism study pointed out that circ_TNPO1 and Notch1 are direct-acting targets of miR-181b. Conclusions: In conclusion, our study indicated that circ_TNPO1 promotes the proliferation and migration progression of VSMCs in atherosclerosis through the miR-181b/Notch1 axis.

Core Protein-Directed Antivirals and Importin ß Can Synergistically Disrupt Hepatitis B Virus Capsids.

Viral structural proteins can have multiple activities. Antivirals that target structural proteins have potential to exhibit multiple antiviral mechanisms. Hepatitis B virus (HBV) core protein (Cp) is involved in most stages of the viral life cycle; it assembles into capsids, packages viral RNA, is a metabolic compartment for reverse transcription, interacts with nuclear trafficking machinery, and disassembles to release the viral genome into the nucleus. During nuclear localization, HBV capsids bind to host importins (e.g., Impß) via Cp's C-terminal domain (CTD); the CTD is localized to the interior of the capsid and is transiently exposed on the exterior. We used HAP12 as a representative Cp allosteric modulator (CpAM), a class of antivirals that inappropriately stimulates and misdirects HBV assembly and deforms capsids. CpAM impact on other aspects of the HBV life cycle is poorly understood. We investigate how HAP12 influences the interactions between empty or RNA-filled capsids with Impß and trypsin in vitro. We show that HAP12 can modulate CTD accessibility and capsid stability, depending on the saturation of HAP12-binding sites. We demonstrate that Impß synergistically contributes to capsid disruption at high levels of HAP12 saturation, using electron microscopy to visualize the disruption and rearrangement of Cp dimers into aberrant complexes. However, RNA-filled capsids resist the destabilizing effects of HAP12 and Impß. In summary, we show host protein-induced catalysis of capsid disruption, an unexpected additional mechanism of action for CpAMs. Potentially, untimely capsid disassembly can hamper the HBV life cycle and also cause the virus to become vulnerable to host innate immune responses. IMPORTANCE The HBV core, an icosahedral complex of 120 copies of the homodimeric core (capsid) protein with or without packaged nucleic acid, is transported to the host nucleus by its interaction with host importin proteins. Importin-core interaction requires the core protein C-terminal domain, which is inside the capsid, to "flip" to the capsid exterior. Core protein-directed drugs that affect capsid assembly and stability have been developed recently. We show that these molecules can, synergistically with importins, disrupt capsids. This mechanism of action, synergism with host protein, has the potential to disrupt the virus life cycle and activate the innate immune system.

Antifungal and Antioxidant Activities of Vernonia Chalybaea Mart. ex DC. Essential Oil and their Major Constituent β -caryophyllene

Abstract: This article describes the chemical composition of Vernonia chalybaea essential oil, and investigates its antimicrobial, antioxidant and hemolytic activities. The evaluation of the antifungal activity was performed by the broth microdilution method using strains of yeasts and dermatophytic fungi. The checkerboard technique to find antimicrobial modulatory effects was performed using ketoconazole as standard drug. The antioxidant activity was evaluated by DPPH scavenging assay and β-carotene/linoleic-acid system. The toxicity was characterized by the brine shrimp lethality test and hemolysis bioassays. The essential oil was obtained by hydrodistillation and analyzed by GC-MS method, showing to be rich in the sesquiterpenes β-caryophyllene (39.06%) and bicyclogermacrene (19.69%), and also demonstrated a relevant antifungal activity against strains of Trichophyton rubrum. In the modulatory activity assay, the essential oil of V. chalybaea and β-caryophyllene demonstrated a synergistic interaction with ketoconazole, with increasing of its antifungal action. The antioxidant activity was evidenced mainly by β-carotene/linoleic acid system, with IC50 value of 35.87 ± 0.32 µg/mL. The results suggest that V. chalybaea essential oil and β-caryophyllene are valuable natural medicinal agents with antioxidant and antimicrobial activities.

Nuclear pores form de novo from both sides of the nuclear envelope.

Nuclear pore complexes are multiprotein channels that span the double lipid bilayer of the nuclear envelope. How new pores are inserted into the intact nuclear envelope of proliferating and differentiating eukaryotic cells is unknown. We found that the Nup107-160 complex was incorporated into assembly sites in the nuclear envelope from both the nucleoplasmic and the cytoplasmic sides. Nuclear pore insertion required the generation of Ran guanosine triphosphate in the nuclear and cytoplasmic compartments. Newly formed nuclear pore complexes did not contain structural components of preexisting pores, suggesting that they can form de novo.

beta-Catenin shows an overlapping sequence requirement but distinct molecular interactions for its bidirectional passage through nuclear pores.

beta-Catenin is an example of a typical molecule that can be translocated bidirectionally through nuclear pore complexes (NPCs) on its own in a facilitated manner. In this work the nuclear import and export of beta-catenin were examined to compare the sequence requirement of this molecule and to determine whether molecular interactions required for its bidirectional NPC passage are distinct or not. Deletion analysis of beta-catenin revealed that armadillo repeats 10-12 and the C terminus comprise the minimum region necessary for nuclear migration activity. Further dissection of this fragment showed that the C terminus tail plays an essential role in nuclear migration. The region of beta-catenin required for export substantially overlapped the region required for import. Therefore, the NPC translocation of beta-catenin is apparently reversible, which is consistent with findings reported previously. However, different translocating molecules blocked nuclear import and export of beta-catenin differentially. The data herein indicate that beta-catenin shows an overlapping sequence requirement for its import and export but that bidirectional movement through the NPC proceeds through distinct molecular interactions.

Modulation of nuclear pore topology by transport modifiers.

The nuclear pore complex (NPC) represents the only pathway for macromolecular communication between the nuclear and cytoplasmic compartments of the cell. Nucleocytoplasmic transport requires the interaction of transport receptors with phenylalanine-glycine (FG)-repeats that line the transport pathway through the NPC. Here we examine the effects of transport receptors and amphipathic alcohols on NPC topology using scanning force microscopy. We show that transport receptors that irreversibly bind FG-repeats increase NPC vertical aspect, whereas transport receptors that weakly interact with FG-repeats increase NPC diameter. Interestingly, small polar alcohols likewise increase NPC diameter. These opposing effects agree with the inhibition or enhancement of nuclear transport, respectively, previously ascribed to these agents.