An Importin α Homolog, MOS6, Plays an Important Role in Plant Innate Immunity

SummaryPlant disease resistance is the consequence of an innate defense mechanism mediated by Resistance (R) genes [1]. The conserved structure of one class of R protein is reminiscent of Toll-like receptors (TLRs) and Nucleotide binding oligomerization domain (NOD) proteins—immune-response perception modules in animal cells [2–4]. The Arabidopsis snc1 (suppressor of npr1-1, constitutive, 1) mutant contains a mutation in a TIR-NBS-LRR-type of R gene that renders resistance responses constitutively active without interaction with pathogens [5]. Few components of the downstream signaling network activated by snc1 are known. To search for regulators of R-gene-mediated resistance, we screened for genetic suppressors of snc1. Three alleles of the mutant mos6 (modifier of snc1, 6) partially suppressed constitutive-resistance responses and immunity to virulent pathogens in snc1. Furthermore, the mos6-1 single mutant exhibited enhanced disease susceptibility to a virulent oomycete pathogen. MOS6, identified by positional cloning, encodes importin α3, one of eight α importins in Arabidopsis [6]. α importins mediate the import of specific proteins across the nuclear envelope. We previously reported that MOS3, a protein homologous to human nucleoporin 96, is required for constitutive resistance in snc1 [7]. Our data highlight an essential role for nucleo-cytoplasmic trafficking, especially protein import, in plant innate immunity

Deleteagene: A Fast Neutron Deletion Mutagenesis-Based Gene Knockout System for Plants

Deleteagene™ (Delete-a-gene) is a deletion-based gene knockout system for plants. To obtain deletion mutants for a specific gene, random deletion libraries created by fast neutron mutagenesis are screened by polymerase chain reaction (PCR) using primers flanking the target gene. By adjusting the PCR extension time to preferentially amplify the deletion alleles, deletion mutants can be identified in pools of DNA samples with each sample representing more than a thousand mutant lines. In Arabidopsis, knockout plants for greater than 80% of targeted genes have been obtained from a population of 51 840 lines. A large number of deletion mutants have been identified and multiple deletion alleles are often recovered for targeted loci. In Arabidopsis, the method is very useful for targeting small genes and can be used to find deletion mutants mutating two or three tandem homologous genes. In addition, the method is demonstrated to be effective in rice as a deletion mutant for a rice gene was obtained with a similar approach. Because fast neutron mutagenesis is applicable to all plant genetic systems, Deleteagene™ has the potential to enable reverse genetics for a wide range of plant species

Role of the conserved aspartate and phenylalanine residues in prokaryotic and mitochondrial elongation factor Ts in guanine nucleotide exchange

AbstractThe guanine nucleotide exchange reaction catalyzed by elongation factor Ts is proposed to arise from the intrusion of the side chains of D80 and F81 near the Mg2+ binding site in EF-Tu. D80A and F81A mutants of E. coli EF-Ts were 2–3-fold less active in promoting GDP exchange with E. coli EF-Tu while the D80AF81A mutant was nearly 10-fold less active. The D84 and F85 mutants of EF-Tsmt were 5–10-fold less active in stimulating the activity of EF-Tumt. The double mutation completely abolished the activity of EF-Tsmt

Optron: Better Medical Image Registration via Optimizing in the Loop

Previously, in the field of image registration, there are mainly two paradigms, the traditional optimization-based methods, and the deep-learning-based methods. We designed a robust training architecture that is simple and generalizable. We present Optron, a general training architecture incorporating the idea of optimizing-in-the-loop. By iteratively optimizing the prediction result of a deep learning model through a plug-and-play optimizer module in the training loop, Optron introduces pseudo ground truth to an unsupervised training process. This pseudo supervision provides more direct guidance towards model training compared with unsupervised methods. Utilizing this advantage, Optron can consistently improve the models' performance and convergence speed. We evaluated our method on various combinations of models and datasets, and we have achieved state-of-the-art performance on the IXI dataset, improving the previous state-of-the-art method TransMorph by a significant margin of +1.6% DSC. Moreover, Optron also consistently achieved positive results with other models and datasets. It increases the validation DSC on IXI for VoxelMorph and ViT-V-Net by +2.3% and +2.2% respectively, demonstrating our method's generalizability. Our implementation is publicly available at https://github.com/miraclefactory/optronComment: 10 pages, 5 figures, 4 table

MOS2, a Protein Containing G-Patch and KOW Motifs, Is Essential for Innate Immunity in Arabidopsis thaliana

SummaryInnate immunity is critical for sensing and defending against microbial infections in multicellular organisms. In plants, disease resistance genes (R genes) play central roles in recognizing pathogens and initiating downstream defense cascades [1]. Arabidopsis SNC1 encodes a TIR-NBS-LRR-type R protein with a similar structure to nucleotide binding oligomerization domain (Nod) proteins in animals [2, 3]. A point mutation in the region between the NBS and LRR of SNC1 results in constitutive activation of defense responses in the snc1 mutant. Here, we report the identification and characterization of mos2-1, a mutant suppressing the constitutive defense responses in snc1. Analysis of mos2 single mutants indicated that it is not only required for resistance specified by multiple R genes, but also for basal resistance. Map-based cloning of MOS2 revealed that it encodes a novel nuclear protein that contains one G-patch and two KOW domains and has homologs across the animal kingdom. The presence of both G-patch and KOW domains in the MOS2 protein suggests that it probably functions as an RNA binding protein critical for plant innate immunity [4, 5]. Our discovery on the biological functions of MOS2 will shed light on functions of the MOS2 homologs in animals, where they may also play important roles in innate immunity

Mutations in an Atypical TIR-NB-LRR-LIM Resistance Protein Confer Autoimmunity

In order to defend against microbial infection, plants employ a complex immune system that relies partly on resistance (R) proteins that initiate intricate signaling cascades upon pathogen detection. The resistance signaling network utilized by plants is only partially characterized. A genetic screen conducted to identify novel defense regulators involved in this network resulted in the isolation of the snc6-1D mutant. Positional cloning revealed that this mutant contained a molecular lesion in the chilling sensitive 3 (CHS3) gene, thus the allele was renamed chs3-2D. CHS3 encodes a TIR-NB-LRR R protein that contains a C-terminal zinc-binding LIM (Lin-11, Isl-1, Mec-3) domain. Although this protein has been previously implicated in cold stress and defense response, the role of the LIM domain in modulating protein activity is unclear. The chs3-2D allele contains a G to A point mutation causing a C1340 to Y1340 substitution close to the LIM domain. It encodes a dominant gain-of-function mutation. The chs3-2D mutant is severely stunted and displays curled leaf morphology. Additionally, it constitutively expresses PATHOGENESIS-RELATED (PR) genes, accumulates salicylic acid, and shows enhanced resistance to the virulent oomycete isolate Hyaloperonospora arabidopsidis (H.a.) Noco2. Subcellular localization assays using GFP fusion constructs indicate that both CHS3 and chs3-2D localize to the nucleus. A third chs3 mutant allele, chs3-3D, was identified in an unrelated genetic screen in our lab. This allele contains a C to T point mutation resulting in an M1017 to V1017 substitution in the LRR–LIM linker region. Additionally, a chs3-2D suppressor screen identified two revertant alleles containing secondary mutations that abolish the mutant morphology. Analysis of the locations of these molecular lesions provides support for the hypothesis that the LIM domain represses CHS3 R-like protein activity. This repression may occur through either autoinhibition or binding of a negative defense regulator

Mesenchymal Stem Cell-Derived Exosomes for Myocardial Infarction Treatment

Myocardial infarction (MI) is a major cause of morbidity and mortality in modern society. Over the past decades, mesenchymal stem cell (MSCs)-based therapy has shown promising results in the treatment of MI due to their unique properties of multi-differentiation ability, immune-privileged phenotype and paracrine activity. Recently, MSC-derived exosomes (MSC-EXO) have been proposed as a promising therapeutic strategy for MI with their ability to inhibit cardiomyocyte apoptosis and stimulate vascular angiogenesis. They also aid immunoregulation and rejuvenation of cardiomyocyte senescence by transporting their unique content such as proteins, lipids, and miRNAs. Compared with MSC transplantation, MSC-EXO administration has shown several advantages, including lower toxicity and immunogenicity and no risk of tumor formation. Nonetheless the potential mechanisms underlying MSC-EXO-based therapy for MI are not fully understood. In addition, lack of modification of MSC-EXOs can impact therapeutic efficacy. It is vital to optimize MSC-EXO and enhance their therapeutic efficacy for MI. We summarize the recent advances regarding biological characteristics, therapeutic potential and mechanisms, and optimal approaches to the use of MSC-EXOs in the treatment of MI

Performance assessment of medical service for organ transplant department based on diagnosis-related groups: A programme incorporating ischemia-free liver transplantation in China

BackgroundIn July 2017, the first affiliated hospital of Sun Yat-sen university carried out the world’s first case of ischemia-free liver transplantation (IFLT). This study aimed to evaluate the performance of medical services pre- and post-IFLT implementation in the organ transplant department of this hospital based on diagnosis-related groups, so as to provide a data basis for the clinical practice of the organ transplant specialty.MethodsThe first pages of medical records of inpatients in the organ transplant department from 2016 to 2019 were collected. The China version Diagnosis-related groups (DRGs) were used as a risk adjustment tool to compare the income structure, service availability, service efficiency and service safety of the organ transplant department between the pre- and post-IFLT implementation periods.ResultsIncome structure of the organ transplant department was more optimized in the post-IFLT period compared with that in the pre-IFLT period. Medical service performance parameters of the organ transplant department in the post-IFLT period were better than those in the pre-IFLT period. Specifically, case mix index values were 2.65 and 2.89 in the pre- and post-IFLT periods, respectively (p = 0.173). Proportions of organ transplantation cases were 14.16 and 18.27%, respectively (p < 0.001). Compared with that in the pre-IFLT period, the average postoperative hospital stay of liver transplants decreased by 11.40% (30.17 vs. 26.73 days, p = 0.006), and the average postoperative hospital stay of renal transplants decreased by 7.61% (25.23 vs.23.31 days, p = 0.092). Cost efficiency index decreased significantly compared with that in the pre-IFLT period (p < 0.001), while time efficiency index fluctuated around 0.83 in the pre- and post-IFLT periods (p = 0.725). Moreover, the average postoperative hospital stay of IFLT cases was significantly shorter than that of conventional liver transplant cases (p = 0.001).ConclusionThe application of IFLT technology could contribute to improving the medical service performance of the organ transplant department. Meanwhile, the DRGs tool may help transplant departments to coordinate the future delivery planning of medical service