Rhesus monkey TRIM5α protein SPRY domain contributes to AP-1 activation.

TRIM5α is an important host restriction factor that could potently block retrovirus infection. The SPRY domain of TRIM5α mediates post-entry restriction by recognition of and binding to the retroviral capsid. Human TRIM5α also functions as an innate immune sensor to activate AP-1 and NF-κB signaling, which subsequently restrict virus replication. Previous studies have shown that the AP-1 and NF-κB signaling activation relies on the RING motif of TRIM5α. In this study, we have demonstrated that the SPRY domain is essential for rhesus macaque TRIM5α to activate AP-1 but not NF-κB signaling. The AP-1 activation mainly depends on all of the ß-sheet barrel on SPRY structure of TRIM5α. Furthermore, the SPRY-mediated auto-ubiquitination of TRIM5α is required for AP-1 activation. This study reports that rhesus macaque TRIM5α mainly undergoes Lys27-linked and Met1-linked auto-polyubiquitination. Finally, we found that the TRIM5α signaling function was positively correlated with its retroviral restriction activity. This study discovered an important role of the SPRY domain in immune signaling and antiviral activity and further expanded our knowledge of the antiviral mechanism of TRIM5α.

Core-binding factor subunit beta is not required for non-primate lentiviral Vif-mediated APOBEC3 degradation.

Viral infectivity factor (Vif) is required for lentivirus fitness and pathogenicity, except in equine infectious anemia virus (EIAV). Vif enhances viral infectivity by a Cullin5-Elongin B/C E3 complex to inactivate the host restriction factor APOBEC3. Core-binding factor subunit beta (CBF-ß) is a cell factor that was recently shown to be important for the primate lentiviral Vif function. Non-primate lentiviral Vif also degrades APOBEC3 through the proteasome pathway. However, it is unclear whether CBF-ß is required for the non-primate lentiviral Vif function. In this study, we demonstrated that the Vifs of non-primate lentiviruses, including feline immunodeficiency virus (FIV), bovine immunodeficiency virus (BIV), caprine arthritis encephalitis virus (CAEV), and maedi-visna virus (MVV), do not interact with CBF-ß. In addition, CBF-ß did not promote the stability of FIV, BIV, CAEV, and MVV Vifs. Furthermore, CBF-ß silencing or overexpression did not affect non-primate lentiviral Vif-mediated APOBEC3 degradation. Our results suggest that non-primate lentiviral Vif induces APOBEC3 degradation through a different mechanism than primate lentiviral Vif. Importance: The APOBEC3 protein family members are host restriction factors that block retrovirus replication. Vif, an accessory protein of lentivirus, degrades APOBEC3 to rescue viral infectivity by forming Cullin5-Elongin B/C-based E3 complex. CBF-ß was proved to be a novel regulator of primate lentiviral Vif function. In this study, we found that CBF-ß knockdown or overexpression did not affect FIV Vif's function, which induced polyubiquitination and degradation of APOBEC3 by recruiting the E3 complex in a manner similar to that of HIV-1 Vif. We also showed that other non-primate lentiviral Vifs did not require CBF-ß to degrade APOBEC3. CBF-ß did not interact with non-primate lentiviral Vifs or promote their stability. These results suggest that a different mechanism exists for the Vif-APOBEC interaction and that non-primates are not suitable animal models for exploring pharmacological interventions that disrupt Vif-CBF-ß interaction.

Circular RNA hsa_circ_0004381 Promotes Neuronal Injury in Parkinson's Disease Cell Model by miR-185-5p/RAC1 Axis.

The study aims to explore the molecular mechanism involved in Parkinson's disease (PD). Hsa_circ_0004381, microRNA-185-5p (miR-185-5p), and Rac family small GTPase 1 (RAC1) level were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Furthermore, cell viability and apoptosis rate were assessed by Cell Counting Kit-8 (CCK-8) and flow cytometry assays, respectively. Protein levels of B cell lymphoma-2 (Bcl-2), Bcl-2-related X protein (Bax), cleaved-caspase 3 (c-caspase 3), and RAC1 were determined by western blot assay. The levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and IL-6 were detected by enzyme-linked immunosorbent assay (ELISA). The ROS generation and LDH and SOD activity were detected by the corresponding kits. The binding relationship between miR-185-5p and hsa_circ_0004381 or RAC1 was predicted by Starbase and then verified by a dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. Hsa_circ_0004381 and RAC1 were increased, and miR-185-5p was decreased in MPP+-triggered SK-N-SH cells. Moreover, hsa_circ_0004381 silencing promoted cell viability, and repressed apoptosis, inflammatory response, and oxidative stress in MPP+-treated SK-N-SH cells. The mechanical analysis suggested that hsa_circ_0004381 served as a sponge of miR-185-5p to affect RAC1 expression. Hsa_circ_0004381 could contribute to MPP+-triggered neuron injury by targeting the miR-185-5p/RAC1 axis, which provided a novel insight into the pathogenesis and treatment of PD.

LncRNA JHDM1D-AS1 Suppresses MPP + -Induced Neuronal Injury in Parkinson's Disease via miR-134-5p/PIK3R3 Axis.

Parkinson's disease (PD) is a multi-factorial neurodegenerative disease. Long noncoding RNAs (lncRNAs) have been revealed to be involved in the process of PD. Herein, this study aimed to investigate the potential function and mechanism of JHDM1D-AS1 (JHDM1D antisense 1) in PD process. 1-Methyl-4-phenylpyridinium (MPP +)-induced SK-N-SH cells were used to conduct expression and function analyses. Levels of genes and proteins were examined using real-time reverse transcription PCR (RT-qPCR) and Western blot. Cell viability and apoptosis were determined using CCK-8 assay, flow cytometry, and Western blot, respectively. ELISA analysis was performed for the detection of interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α. The contents of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured using commercial kits. The direct interactions between miR-134-5p and PIK3R3 (Phosphoinositide-3-Kinase Regulatory Subunit 3) or JHDM1D-AS1 were verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. JHDM1D-AS1 expression was decreased by MPP + in SK-N-SH cells in a dose- or time-dependent manner. Functionally, JHDM1D-AS1 overexpression attenuated MPP + -evoked neuronal apoptosis, inflammation, and oxidative stress. Mechanistically, JHDM1D-AS1 competitively bound to miR-134-5p to upregulate the expression of its target PIK3R3. Rescue experiments suggested that miR-134-5p upregulation reversed the inhibitory effects of JHDM1D-AS1 on MPP + -induced neuronal injury. Moreover, inhibition of miR-134-5p protected neurons against MPP + -induced neuronal apoptosis, inflammation, and oxidative stress, which were abolished by PIK3R3 silencing. JHDM1D-AS1 protected against MPP + -induced neuron injury via miR-134-5p/PIK3R3 axis, suggesting the potential involvement of this axis in PD process.