CD47 serves as a ligand for signaling regulatory protein α (SIRPα) and as a receptor for thrombospondin‐1 (TSP‐1). Although CD47, TSP‐1, and SIRPα are thought to be involved in the clearance of aged ...red blood cells (RBCs), aging‐associated changes in the expression and interaction of these molecules on RBCs have been elusive. Using direct stochastic optical reconstruction microscopy (dSTORM)‐based imaging and quantitative analysis, we can report that CD47 molecules on young RBCs reside as nanoclusters with little binding to TSP‐1, suggesting a minimal role for TSP‐1/CD47 signaling in normal RBCs. On aged RBCs, CD47 molecules decreased in number but formed bigger and denser clusters, with increased ability to bind TSP‐1. Exposure of aged RBCs to TSP‐1 resulted in a further increase in the size of CD47 clusters via a lipid raft‐dependent mechanism. Furthermore, CD47 cluster formation was dramatically inhibited on thbs1−/− mouse RBCs and associated with a significantly prolonged RBC lifespan. These results indicate that the strength of CD47 binding to its ligand TSP‐1 is predominantly determined by the distribution pattern and not the amount of CD47 molecules on RBCs, and offer direct evidence for the role of TSP‐1 in phagocytosis of aged RBCs. This study provides clear nanoscale pictures of aging‐associated changes in CD47 distribution and TSP‐1/CD47 interaction on the cell surface, and insights into the molecular basis for how these molecules coordinate to remove aged RBCs.
On young RBCs (Top), CD47 molecules reside as nanoclusters with minimal binding to TSP‐1 trimmers. On aged RBCs (Bottom), CD47 proteins form bigger and denser clusters and gain increased ability to bind TSP‐1, thus promoting phagocytosis of aged RBCs.
Research progress on post-stroke depression Zhou, Hui; Wei, Yu-Jiao; Xie, Guang-Yao
Experimental neurology,
March 2024, 2024-Mar, 2024-03-00, 20240301, Letnik:
373
Journal Article
Recenzirano
Stroke is a highly prevalent and widely detrimental cardiovascular disease, frequently resulting in impairments of both motor function and neural psychological capabilities, such as post-stroke ...depression (PSD). PSD is the most prevalent neuropsychological disorder among stroke patients, characterized by persistent emotional lowness and diminished interest as its primary features. This article summarizes the mechanism research, animal models and related treatments of PSD. Further improvements are needed in the screening of research subjects and the construction of animal models in the study of PSD. At the same time, in the study of the mechanism of PSD, we need to consider the interaction between multiple systems. The treatment of PSD requires more careful consideration. This can help us to find something new in the study of the mechanism of complex PSD, which provides a new direction for us to develop new treatment delivery.
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The Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）-associated protein 9 （CRISPR/Cas9）-based genomeediting system is a revolutionary technology for targeted muta- genesis in ...molecular biology research and genetic improvement of traits in crops （Cong et al., 2013; Ma et al., 2015, 2016）. Agronomic traits of crops are controlled by major genes and quantitative trait loci （QTL）. Therefore, the CRISPR/Cas9 system can be used to effectively and rapidly produce mutant traits by different strategies （Figure 1A-1C）. The most common application of the targeted editing system in genetic improvement is to knock out completely the functions of target genes, usually by editing site（s） in the coding sequences （CDS） to produce null-allele mutants （Figure 1A）.
Dear Editor,
The transcription activator-like effector nucleases （TALENs） and clustered regularly interspaced short palindromic repeats （CRISPR）/Cas9 genome editing systems have greatly improved the ...efficiency for generating targeted mutations in various organisms including plants （Li et al., 2012; Cong et al., 2013; Li et al., 2013; Feng et al., 2014; Ma et al., 2015b; Zhang et al., 2014, 2015）. In some plant species, the majority of mutations induced by TALENs and CRISPR/Cas9 systems are in uniform biallelic and heterozygous status in the first transgenic generation, although in some other plant species, chimeric mutations （with three or more allelic edited events within a single individual） may frequently occur （Li et al., 2013; Feng et al., 2014; Zhang et al., 2014, 2015; Ma et al., 2015b）. In many cases, it is necessary to determine the mutated sequences of the targeted alleles. However, direct sequencing （with the Sanger method） of PCR amplicons containing such biallelic or heterozygous mutations results in superimposed sequencing peaks starting from the mutation sites. Therefore, cloning of the mutation- containing amplicons and sequencing of multiple clones for each target editing site are required to determine the mutated sequences of the targeted alleles, which is tedious, time consuming, and expensive. Aimed at this problem, we have recently developed a highly reliable Degenerate Sequence De- coding （DSD） method （Ma et al., 2015a） and applied it to decode hundreds of targeted mutation events in rice and Arabidopsis （Ma et al., 2015b）. The DSD method decodes superimposed sequencing chromatograms in the following steps： （1） starting from the first overlapping-peak position on the chromatogram, manually generate a short degenerate sequence （DS） that is adjacent to the anchor sequence （AS）, which sits upstream of the first overlapping-peak; （2） query the DS against the intact reference sequence twice with a sequence analysis program to find the matched sequence（s）; and （3） link the AS with the query-matched sequences to generate the allele sequences or, if detecting only one matching hit, generate the second allele sequence by subtracting the allele 1 nucleotides from the degenerate bases. Even though simple and highly efficient, manual operation of this DSD method is still time consuming when decoding a large number of superimposed sequencing chromatograms.
Dear Editor, Male reproductive development is an essential biological process for flowering plants and crucial for crop seed produc- tion. Formation of the male reproductive organ, the anther, ...involves a number of developmental events, including sta- men meristem specification, generation of sporogenous cells and their differentiation into microspore mother cells （MMCs）, meiosis, microspore （pollen） maturation, and polli- nation （Ma, 2005）. The formation of microspores and their development into mature pollen grains require cooperative interactions between gametophytic （microspores） and sporo- phytic （anther wall） cells, with the innermost cell layer, the tapetum, playing the most crucial role （Ma, 2005）. Tapetal cells underao decleneration bv Droclrammed cell death （PCD）.
Plant mutants are important bio-resources for crop breeding and gene functional studies. Conventional methods for generating mutant libraries by mutagenesis of seeds with physical or chemical agents ...are of low efficiency. Here, we developed a highly-efficient ethyl methanesulfonate （EMS） mutagenesis system based on suspension-cultured cells, with rice （Oryza sativa L.） as an example. We show that treatment of suspension-cultured tiny cell clusters with 0.4% EMS for 18-22 h followed by differentiation and regeneration produced as high as 29.4% independent mutant lines with visible phenotypic variations, including a number of important agronomic traits such as grain size, panicle size, grain or panicle shape, tiller number and angle, heading date, male sterility, and disease sensitivity. No mosaic mutant was observed in the mutant lines tested. In this mutant library, we obtained a mutant with an abnormally elongated uppermost internode. Sequencing and functional analysis revealed that this is a new allelic mutant of eui （elongated uppermost internode） caused by two point mutations in the first exon of the EUI gene, representing a successful example of this mutagenesis system.
CRISPR/Cas9 genome targeting systems have been applied to a variety of species. However, most CRISPR/Cas9 systems reported for plants can only modify one or a few target sites. Here, we report a ...robust CRISPR/Cas9 vector system, utilizing a plant codon optimized Cas9 gene, for convenient and high- efficiency multiplex genome editing in monocot and dicot plants. We designed PCR-based procedures to rapidly generate multiple sgRNA expression cassettes, which can be assembled into the binary CRISPR/ Cas9 vectors in one round of cloning by Golden Gate ligation or Gibson Assembly. With this system, we edi- ted 46 target sites in rice with an average 85.4% rate of mutation, mostly in biallelic and homozygous status. We reasoned that about 16% of the homozygous mutations in rice were generated through the non-homol- ogous end-joining mechanism followed by homologous recombination-based repair. We also obtained uni- form biallelic, heterozygous, homozygous, and chimeric mutations in Arabidopsis T1 plants. The targeted mutations in both rice and Arabidopsis were heritable. We provide examples of loss-of-function gene mu- tations in To rice and T1Arabidopsis plants by simultaneous targeting of multiple （up to eight） members of a gene family, multiple genes in a biosynthetic pathway, or multiple sites in a single gene. This system has provided a versatile toolbox for studying functions of multiple genes and gene families in plants for basic research and genetic improvement.
Anthocyanins have high antioxidant activities, and engineering of anthocyanin biosynthesis in staple crops, such as rice （Oryza sativa L.）, could provide health-promoting foods for improving human ...health. However, engineering metabolic pathways for biofortification remains difficult, and previous attempts to engineer anthocyanin production in rice endosperm failed because of the sophisticated genetic regulatory network of its biosynthetic pathway. In this study, we developed a high-efficiency vector system for transgene stacking and used it to engineer anthocyanin biosynthesis in rice endosperm. We made a construct containing eight anthocyanin-related genes （two regulatory genes from maize and six structural genes from Coleus） driven by the endosperm-specific promoters,plus a selectable marker and a gene for marker excision. Transformation of rice with this construct generated a novel biofortified germplasm ＂Purple Endosperm Rice＂ （called ＂Zijingmi＂ in Chinese）, which has high anthocyanin contents and antioxidant activity in the endosperm. This anthocyanin production results from expression of the transgenes and the resulting activation （or enhancement） of expression of 13 endogenous anthocyanin biosynthesis genes that are silenced or expressed at low levels in wild-type rice endosperm. This study provides an efficient, versatile toolkit for transgene stacking and demonstrates its use for successful engineering of a sophisticated biological pathway, suggesting the potential utility of this toolkit for synthetic biology and improvement of agronomic traits in plants.
New gene origination is a major source of genomic innovations that confer phenotyp ic changes and biological di- versity. Generation of new mitochondrial genes in plants may cause cytoplasmic male ...sterility （CMS）, which can pro- mote outcrossing and increase fitness. However, how mitochondrial genes originate and evolve in structure and func- tion remains unclear. The rice Wild Abortive type of CMS is conferred by the mitochondrial gene WA352c （previously named WA352） and has been widely exploited in hybrid rice breeding. Here, we reconstruct the evolutionary tra- jectory of WA352c by the identification and analyses of 11 mitochondrial genomic recombinant structures related to WA352c in wild and cultivated rice. We deduce that these structures arose through multiple rearrangements among conserved mitochondrial sequences in the mitochondrial genome of the wild rice Oryza rufipogon, coupled with sub- stoichiometric shifting and sequence variation. We identify two expressed but nonfunctional protogenes among these structures, and show that they could evolve into functional CMS genes via sequence variations that could relieve the self-inhibitory potential of the proteins. These sequence changes would endow the proteins the ability to interact with the nucleus-encoded mitochondrial protein COXI1, resulting in premature programmed cell death in the anther ta- petum and male sterility. Furthermore, we show that the sequences that encode the COXll-interaction domains in these WA352c-related genes have experienced purifying selection during evolution. We propose a model for the for- mation and evolution of new CMS genes via a ＂multi-recombination/protogene formation/functionalization＂ mecha- nism involving gradual variations in the structure, sequence, copy number, and function.
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