Considerable efforts have been made on the development of lipid nanoparticles (LNPs) for delivering of nucleic acids in LNP-based medicines, including a first-ever short interfering RNA (siRNA) ...medicine, Onpattro, and the mRNA vaccines against the coronavirus disease 2019 (COVID-19), which have been approved and are currently in use worldwide. The successful rational design of ionizable cationic lipids was a major breakthrough that dramatically increased delivery efficiency in this field. The LNPs would be expected to be useful as a platform technology for the delivery of various therapeutic modalities for genome editing and even for undiscovered therapeutic mechanisms. In this review, the current progress of my research, including the molecular design of pH-sensitive cationic lipids, their applications for various tissues and cell types, and for delivering various macromolecules, including siRNA, antisense oligonucleotide, mRNA, and the clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) system will be described. Mechanistic studies regarding relationships between the physicochemical properties of LNPs, drug delivery, and biosafety are also summarized. Furthermore, current issues that need to be addressed for next generation drug delivery systems are discussed.
Summary
Ubiquitination is a post-translational modification system essential for regulating a wide variety of biological processes in eukaryotes. Ubiquitin (Ub) itself undergoes post-translational ...modifications, including ubiquitination. All seven lysine residues and one N-terminal amino group of Ub can act as acceptors for further ubiquitination, producing eight types of Ub chains. Ub chains of different linkage types have different cellular functions and are referred to as the ‘ubiquitin code’. Decoder molecules that contain linkage-specific Ub-binding domains (UBDs) recognize the Ub chains to regulate different cellular functions. On the other hand, deubiquitinases (DUBs) cleave Ub chains to reverse ubiquitin signals. This review discusses the molecular mechanisms of linkage-specific recognitions of Ub chains by UBDs and DUBs, which have been revealed by structural studies.
Graphical Abstract
Graphical Abstract
This study examined the relative effectiveness of recasts, explicit correction, and metalinguistic prompts on developing English past progressive forms among second language (L2) learners, and ...whether the effectiveness of each feedback type was differently associated with L2 proficiency. A total of 197 Japanese learners of English as a foreign language were divided into recast, explicit correction, metalinguistic prompt, task-only, and test control groups. The first three groups performed tasks and received corrective feedback (CF). The task-only group performed the same tasks as the CF groups but did not receive CF. The test control group did not perform the tasks and solely took pretests and posttests. The results showed that explicit types of feedback (explicit correction and metalinguistic prompts) were more effective than implicit feedback (recasts). Further, simple regression analyses showed that L2 proficiency was significantly associated with gains in scores of the recast and metalinguistic prompt groups but not the explicit correction group. These results suggest that L2 proficiency differentially influences the effectiveness of different CF types.
This study examined the effects of three different types of corrective feedback (CF) on the acquisition of declarative/procedural knowledge of the English past tense in a foreign language (FL) ...classroom setting. The participants comprised Japanese university students, and five classes were assigned to recasts, explicit correction, metalinguistic prompt, task-only, and test control groups. The first three groups performed tasks designed to elicit past-tense forms and received CF. The task-only group performed the tasks without any CF, while the test control group completed pretests and posttests only. Participants’ declarative and procedural knowledge of the past tense was measured at the pretest, immediate posttest, and delayed posttest. The results generally showed that recasts and explicit correction were effective for the development of declarative knowledge of the structures, while metalinguistic prompts were beneficial for the development of procedural knowledge. Thus, metalinguistic prompts would be one of the best types of feedback to provide in an FL classroom setting to help learners develop procedural knowledge of past-tense forms. However, to effectively develop their declarative knowledge of past-tense forms, recasts and explicit correction should also be provided.
Photovoltaic (PV) systems having rechargeable batteries are prone to be complex and costly because multiple converters are necessary to individually regulate a load, PV panel, and battery. This paper ...proposes novel nonisolated multiport converters (MPCs) integrating a bidirectional pulsewidth modulation (PWM) converter and phase-shift-switched capacitor converter (PS-SCC) for standalone PV systems. A PWM converter and PS-SCC are integrated by reducing the total switch count, realizing the simplified system and circuit. In the proposed MPCs, two control freedoms of duty cycle and phase shift angle are manipulated to individually regulate the load, PV panel, and/or battery. The detailed operation analysis was performed to mathematically derive gain characteristics and zero voltage switching operation boundaries. For the battery discharging mode, in which the PV panel is not available and the MPC behaves as a single-input-single-output converter with two control freedoms available, the optimized control scheme achieving the lowest rms current is also proposed to maximize power conversion efficiencies. Various kinds of experimental verification tests using a 200-W prototype were performed to verify the theoretical analysis and to demonstrate the performance of the proposed MPC.
To elucidate differential roles of mutations in myelodysplastic syndromes (MDS), we investigated clonal dynamics using whole-exome and/or targeted sequencing of 699 patients, of whom 122 were ...analyzed longitudinally. Including the results from previous reports, we assessed a total of 2,250 patients for mutational enrichment patterns. During progression, the number of mutations, their diversity and clone sizes increased, with alterations frequently present in dominant clones with or without their sweeping previous clones. Enriched in secondary acute myeloid leukemia (sAML; in comparison to high-risk MDS), FLT3, PTPN11, WT1, IDH1, NPM1, IDH2 and NRAS mutations (type 1) tended to be newly acquired, and were associated with faster sAML progression and a shorter overall survival time. Significantly enriched in high-risk MDS (in comparison to low-risk MDS), TP53, GATA2, KRAS, RUNX1, STAG2, ASXL1, ZRSR2 and TET2 mutations (type 2) had a weaker impact on sAML progression and overall survival than type-1 mutations. The distinct roles of type-1 and type-2 mutations suggest their potential utility in disease monitoring.
The tumor-microenvironment contains large numbers of tumor-associated macrophages (TAMs) which are largely M2 phenotypes and are involved in pro-tumorous functions. Targeting TAMs so as to manipulate ...them and to modify their functions could be a novel immunotherapy for the treatment of cancer. Such a strategy would involve targeting TAMs with short interfering RNA (siRNA) to modify their functions by silencing certain genes that are responsible for their M2 polarization. In this study, a lipid nanoparticle (LNP) formulation was used to target and deliver siRNA to TAMs. The LNP was mainly composed of a novel, pH-sensitive cationic lipid, referred to as the CL4H6 lipid, which had previously been optimized to target hepatocytes. The optimized siRNA-loaded CL4H6-LNPs were selectively and efficiently taken up and showed strong gene silencing activity in TAMs in a human tumor xenograft model in nude mice. Furthermore, an anti-tumor therapeutic response in the same tumor model was obtained by targeting TAMs using the optimized siRNA-loaded CL4H6-LNPs. The anti-tumor therapeutic response was obtained through the silencing of the signal transducer and activator of transcription 3 (STAT3) and hypoxia inducible factor 1 α (HIF-1α), which resulted in an increase in the level of infiltrated macrophage (CD11b+ cells) into the tumor-microenvironment (TME) as well as a tendency to increase the concentration of M1 macrophages (CD169+ cells). The treatment also resulted in reversing the pro-tumorous functions of TAMs -mainly angiogenesis and tumor cell activation-, as evidenced by a decrease in the related gene expression at the mRNA level. This research has promising clinical and pharmaceutical applications for achieving novel macrophage-based cancer immunotherapy.
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In patients with acquired aplastic anemia, destruction of hematopoietic cells by the immune system leads to pancytopenia. Patients have a response to immunosuppressive therapy, but myelodysplastic ...syndromes and acute myeloid leukemia develop in about 15% of the patients, usually many months to years after the diagnosis of aplastic anemia.
We performed next-generation sequencing and array-based karyotyping using 668 blood samples obtained from 439 patients with aplastic anemia. We analyzed serial samples obtained from 82 patients.
Somatic mutations in myeloid cancer candidate genes were present in one third of the patients, in a limited number of genes and at low initial variant allele frequency. Clonal hematopoiesis was detected in 47% of the patients, most frequently as acquired mutations. The prevalence of the mutations increased with age, and mutations had an age-related signature. DNMT3A-mutated and ASXL1-mutated clones tended to increase in size over time; the size of BCOR- and BCORL1-mutated and PIGA-mutated clones decreased or remained stable. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and longer and a higher rate of overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes. However, clonal dynamics were highly variable and might not necessarily have predicted the response to therapy and long-term survival among individual patients.
Clonal hematopoiesis was prevalent in aplastic anemia. Some mutations were related to clinical outcomes. A highly biased set of mutations is evidence of Darwinian selection in the failed bone marrow environment. The pattern of somatic clones in individual patients over time was variable and frequently unpredictable. (Funded by Grant-in-Aid for Scientific Research and others.).
Lipid nanoparticles (LNPs) are one of the more promising technologies for efficiently delivering nucleic acids in vivo. Hepatocytes are the primary target cells of LNPs that are delivered via the ...apolipoprotein E (ApoE)-low density lipoprotein receptor (LDLR) pathway, an endogenous targeting pathway. This robust targeting mechanism results in the specific and efficient delivery of nucleic acids to hepatocytes. Trivalent N-acetyl-D-galactosamine (GalNAc) is known to be a high-affinity exogenous ligand against the asialoglycoprotein receptor (ASGPR), which is highly expressed on hepatocytes. In this study, we report that the kinetics of the hepatic uptake process between the two types of targeting pathways are different. Rapid blood clearance, accumulation to the space of Disse and a subsequent slow cellular uptake was observed in the case of the endogenous ApoE-LDLR pathway. On the other hand, both blood clearance and cellular uptake were more gradual in the case of the exogenous GalNAc-ASGPR pathway. Interactions between ApoE-bound LNPs and hepatic heparan sulfate proteoglycans (HSPGs) were involved in the rapid blood clearance and accumulation to the space of Disse in the case of the endogenous pathway. The findings presented here contribute to a more precise understanding of the mechanism of hepatic uptake and to the rational design of hepatocyte-targeting nanoparticles.
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