Engineered Exosomes Containing microRNA-29b-2 and Targeting the Somatostatin Receptor Reduce Presenilin 1 Expression and Decrease the ß-Amyloid Accumulation in the Brains of Mice with Alzheimer's Disease.

Purpose: Exosomes are membrane vesicles secreted by various cells and play a crucial role in intercellular communication. They can be excellent delivery vehicles for oligonucleotide drugs, such as microRNAs, due to their high biocompatibility. MicroRNAs have been shown to be more stable when incorporated into exosomes; however, the lack of targeting and immune evasion is still the obstacle to the use of these microRNA-containing nanocarriers in clinical settings. Our goal was to produce functional exosomes loaded with target ligands, immune evasion ligand, and oligonucleotide drug through genetic engineering in order to achieve more precise medical effects. Methods: To address the problem, we designed engineered exosomes with exogenous cholecystokinin (CCK) or somatostatin (SST) as the targeting ligand to direct the exosomes to the brain, as well as transduced CD47 proteins to reduce the elimination or phagocytosis of the targeted exosomes. MicroRNA-29b-2 was the tested oligonucleotide drug for delivery because our previous research showed that this type of microRNA was capable of reducing presenilin 1 (PSEN1) gene expression and decreasing the ß-amyloid accumulation for Alzheimer's disease (AD) in vitro and in vivo. Results: The engineered exosomes, containing miR29b-2 and expressing SST and CD47, were produced by gene-modified dendritic cells and used in the subsequent experiments. In comparison with CD47-CCK exosomes, CD47-SST exosomes showed a more significant increase in delivery efficiency. In addition, CD47-SST exosomes led to a higher delivery level of exosomes to the brains of nude mice when administered intravenously. Moreover, it was found that the miR29b-2-loaded CD47-SST exosomes could effectively reduce PSEN1 in translational levels, which resulted in an inhibition of beta-amyloid oligomers production both in the cell model and in the 3xTg-AD animal model. Conclusion: Our results demonstrated the feasibility of the designed engineered exosomes. The application of this exosomal nanocarrier platform can be extended to the delivery of other oligonucleotide drugs to specific tissues for the treatment of diseases while evading the immune system.

Plasma Membrane-Localized Transporter MdSWEET12 Is Involved in Sucrose Unloading in Apple Fruit.

Sugar content is an important factor determining the flavor in apple fruit. Sugar unloading is a prerequisite step for sugar accumulation. However, little is known about sugar unloading mechanisms in apple. Transcriptomic sequencing of two apple varieties, "Envy" and "Pacific Rose," with significantly different sugar content was performed. MdSWEET12a from the SWEET transporter family was differentially expressed. Further study of the MdSWEET12a showed that this plasma membrane-localized transporter protein-encoding gene was mainly expressed in sieve element-companion cells (SE-CC) in the fruit, which was positively correlated with the sucrose accumulation during the development of "Envy" apple. Consistently manipulating the gene expression through either transient overexpression or silencing significantly increased or decreased the sugar content in apple fruit, respectively. Complementary growth experiments in mutant yeast cells indicated that MdSWEET12a transported sucrose. Heterologous expression of MdSWEET12a in tomato increased the expression of genes related to sugar metabolism and transport, leading to increased sugar content. These findings underpin the involvement of MdSWEET12a in sugar unloading in apple fruit.

Protection mechanism of deacetylase inhibitor on spleen of rats with severe hemorrhagic shock.

OBJECTIVE: To explore the protection and molecular mechanism of histone deacetylase inhibitors (HDACIs) on the spleen of rats with hemorrhagic shock. METHODS: A total of 60 SPF male SD rats were selected for the modeling of severe hemorrhagic shock using the method of arterial and venous cannulation with the time-divided bleeding. The measurement of mean arterial blood pressure and blood lactic acid was used to verify the modeling. The modeled rats were randomly divided into shock group, shock + suberoylanilide hydroxamic acid (SAHA) group, shock + autogenous transfusion group and shock + SAHA + autogenous transfusion group. Three hours after the treatment, the spleen of rats was collected and TUNEL method was employed to detect the apoptosis of spleen cells in each group. The statistical analysis was performed. Afterwards, real-time PCR and western blot were employed to detect the expression of BCL-2, BAX and caspass3 in the spleen of rats in each group. RESULTS: A total of 53 rats had successful modeling of severe hemorrhagic shock, with success rate of 88%. Cell apoptosis in the severe hemorrhagic model group was the most serious. After the intervention of HDACIs and the autogenous transfusion, the tissue injury was a bit recovered. Cell apoptosis was least in the shock + SAHA + autogenous transfusion group (P < 0.05). After the intervention of HDACIs and the autogenous transfusion, the relative expression of BCL-2 was significantly increased (P < 0.05), with highest relative expression of BCL-2 in shock + SAHA + autogenous transfusion group (P < 0.05). After the intervention of HDACIs and the autogenous transfusion, the relative expression of BAX was significantly decreased (P < 0.05), with lowest relative expression of BAX in the intervention group of single HDACIs. The change in the expression of caspass3 was similar to BAX, namely the relative expression of caspass3 was significantly decreased after the intervention of HDACIs and the autogenous transfusion (P < 0.05). CONCLUSIONS: HDACIs and autogenous transfusion can all protect the spleen injury because of the severe hemorrhagic shock. Its molecular mechanism may be related to the regulation on the expression of BCL-2/BAX and caspass3, which may affect the apoptosis process of cells.