EVs-mediated delivery of CB2 receptor agonist for Alzheimer’s disease therapy

Alzheimer’s disease(AD)is a typical neurodegenerative disease that leads to irreversible neuronal degeneration,and effective treatment remains elusive due to the unclear mechanism.We utilized biocompatible mesenchymal stem cell-derived extracellular vesicles as carriers loaded with the CB2 target medicine AM1241(EVs-AM1241)to protect against neurodegenerative progression and neuronal function in AD model mice.According to the results,EVs-AM1241 were successfully constructed and exhibited better bioavailability and therapeutic effects than bare AM1241.The Morris water maze(MWM)and fear conditioning tests revealed that the learning and memory of EVs-AM1241-treated model mice were significantly improved.In vivo electrophysiological recording of CA1 neurons indicated enhanced response to an auditory conditioned stimulus following fear learning.Immunostaining and Western blot analysis showed that amyloid plaque deposition and amyloidβ(Aβ)-induced neuronal apoptosis were significantly suppressed by EVs-AM1241.Moreover,EVs-AM1241 increased the number of neurons and restored the neuronal cytoskeleton,indicating that they enhanced neuronal regeneration.RNA sequencing revealed that EVs-AM1241 facilitated Aβphagocytosis,promoted neurogenesis and ultimately improved learning and memory through the calcium-Erk signaling pathway.Our study showed that EVs-AM1241 efficiently reversed neurodegenerative pathology and enhanced neurogenesis in modelmice,indicating that they are very promising particles for treating AD.

IDDoR:a novel reporter mouse system for simultaneous and quantitative in vivo analysis of both DNA double-strand break repair pathways

Dear Editor,Two distinct pathways,non-homologous end joining(NHEJ)and homologous recombination(HR)repair,have evolved to repair DNA double-strand breaks(DSBs),the most deleterious type of DNA damage.Impaired NHEJ and HR are often associated with a high incidence of tumorigenesis and the early onset of aging.A number of methods and tools have been developed to help elucidate the regulatory mechanisms of the two repair pathways in the past.In vitro biochemical assays employ 32P-labeled broken DNA fragments and cell extracts to evaluate DSB repair capacity.At DSB sites,several DSB repair factors form foci,which can be visualized through immunofluorescence and microscopy.Among them,phosphorylated H2AX at the Ser139 residue is often considered a DSB marker,and its formation and removal at different time points post the induction of DSBs can be used to reflect the repair capacity and genomic instability.In addition,by quantifying the kinetics of the recruitment of specific NHEJ and HR factors such as 53BP1,DNA-PKcs,MRE11,RPA2,and RAD51,one would be able to make judgments on whether NHEJ,HR,or both pathways is/are affected and sometimes at which steps DSB repair pathways are regulated.An alternative approach for kinetic analysis is to quantify the microirradiation-induced recruitment of repair factors.Moreover,comet assays are also utilized to measure DNA damage-induced genomic stability at the single-cell level.However,with these assays,it is still difficult to measure NHEJ and HR efficiency in a relatively less time-consuming and more quantitative manner.

Inhibition of fibroblast activation protein ameliorates cartilage matrix degradation and osteoarthritis progression

Fibroblast activation protein(Fap)is a serine protease that degrades denatured type I collagen,α2-antiplasmin and FGF21.Fap is highly expressed in bone marrow stromal cells and functions as an osteogenic suppressor and can be inhibited by the bone growth factor Osteolectin(Oln).Fap is also expressed in synovial fibroblasts and positively correlated with the severity of rheumatoid arthritis(RA).However,whether Fap plays a critical role in osteoarthritis(OA)remains poorly understood.Here,we found that Fap is significantly elevated in osteoarthritic synovium,while the genetic deletion or pharmacological inhibition of Fap significantly ameliorated posttraumatic OA in mice.Mechanistically,we found that Fap degrades denatured type II collagen(Col II)and Mmp13-cleaved native Col II.Intra-articular injection of r Fap significantly accelerated Col II degradation and OA progression.In contrast,Oln is expressed in the superficial layer of articular cartilage and is significantly downregulated in OA.Genetic deletion of Oln significantly exacerbated OA progression,which was partially rescued by Fap deletion or inhibition.Intra-articular injection of r Oln significantly ameliorated OA progression.Taken together,these findings identify Fap as a critical pathogenic factor in OA that could be targeted by both synthetic and endogenous inhibitors to ameliorate articular cartilage degradation.

Primary cilia support cartilage regeneration after injury

In growing children,growth plate cartilage has limited self-repair ability upon fracture injury always leading to limb growth arrest.Interestingly,one type of fracture injuries within the growth plate achieve amazing self-healing,however,the mechanism is unclear.Using this type of fracture mouse model,we discovered the activation of Hedgehog(Hh)signaling in the injured growth plate,which could activate chondrocytes in growth plate and promote cartilage repair.

多囊卵巢综合征无排卵的胰岛素信号和雄激素合成的新遗传风险和代谢特征

促排卵是多囊卵巢综合征(PCOS)不孕症的一线治疗方案。卵巢对促排卵治疗的排卵应答差被认为与胰岛素抵抗和高雄激素血症相关。在一个包含1000名PCOS不孕妇女(PCOSAct)的前瞻性队列中,我们开展了一项全外显子联合靶向单核苷酸多态性(SNP)测序以及代谢组学研究。在全基因组水平找出与无排卵显著相关的常见变异和罕见突变,并通过机器学习算法构建排卵预测模型。研究发现,ZNF438基因中标记为rs2994652(p=2.47×10^(-8))的常见变异和REC114基因中的一个罕见功能突变(rs182542888,p=5.79×10^(-6))与促排卵治疗失败显著相关。携带rs2994652 A等位基因和REC114 p.Val101Leu(rs182542888)的PCOS不孕妇女进行促排卵治疗的总排卵率更低(分别为比值比(OR)=1.96,95%置信区间(CI)[1.55~2.49];OR=11.52,95%CI[3.08~43.05]),出现排卵的间隔时间更长(平均56.7天vs.49.0天,p<0.001;78.1天vs.68.6天,p=0.014)。对于rs2994652突变者,L-苯丙氨酸水平升高并与胰岛素抵抗稳态模型(HOMA-IR)指数(r=0.22,p=0.05)和空腹血糖(r=0.33,p=0.003)呈正相关;对于rs182542888突变者,花生四烯酸代谢产物水平下降并与升高的抗苗勒管激素(r=-0.51,p=0.01)和总睾酮(r=-0.71,p=0.02)呈负相关。整合基因变异位点、代谢产物及临床特征的联合预测模型可提高对排卵的预测能力[曲线下面积(AUC)=76.7%]。ZNF438基因的一个常见变异和REC114基因的一个罕见功能突变,以及与二者相关的苯丙氨酸和花生四烯酸代谢物改变,与PCOS女性不孕症的促排卵治疗失败相关。

Soxllb regulates the migration and fate determination of Müller glia-derived progenitors during retina regeneration in zebrafish

The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.

Ion elemental-optimized layered double hydroxide nanoparticles promote chondrogenic differentiation and intervertebral disc regeneration of mesenchymal stem cells through focal adhesion signaling pathway

Chronic low back pain and dyskinesia caused by intervertebral disc degeneration(IDD)are seriously aggravated and become more prevalent with age.Current clinical treatments do not restore the biological structure and inherent function of the disc.The emergence of tissue engineering and regenerative medicine has provided new insights into the treatment of IDD.We synthesized biocompatible layered double hydroxide(LDH)nanoparticles and optimized their ion elemental compositions to promote chondrogenic differentiation of human umbilical cord mesenchymal stem cells(hUC-MSCs).The chondrogenic differentiation of LDH-treated MSCs was validated using Alcian blue staining,qPCR,and immunofluorescence analyses.LDH-pretreated hUC-MSCs were differentiated prior to transplantation into the degenerative site of a needle puncture IDD rat model.Repair and regeneration evaluated using X-ray,magnetic resonance imaging,and tissue immunostaining 4-12 weeks after transplantation showed recovery of the disc space height and integrated tissue structure.Transcriptome sequencing revealed significant regulatory roles of the extracellular matrix(ECM)and integrin receptors of focal adhesion signaling pathway in enhancing chondrogenic differentiation and thus prompting tissue regeneration.The construction of ion-specific LDH nanomaterials for in situ intervertebral disc regeneration through the focal adhesion signaling pathway provides theoretical basis for clinical transformation in IDD treatment.

Peripheral actions and direct central-local communications of melanocortin 4 receptor signaling

Melanocortin 4 receptor(MC4R),the most important monogenetic cause of human metabolic disorders,has been of great interest to many researchers in the field of energy homeostasis and public health.Because MC4R is a vital pharmaceutical target for maintaining controllable appetite and body weight for professional athletes,previous studies have mainly focused on the central,rather than the peripheral,roles of MC4R.Thus,the local expression of MC4R and its behavioral regulation remain unclear.In an attempt to shed light on different directions for future studies of MC4R signaling,we review a series of recent and important studies exploring the peripheral functions of MC4R and the direct physiological interaction between peripheral organs and central MC4R neurons in this article.

Gene-knockout by iSTOP enables rapid reproductive disease modeling and phenotyping in germ cells of the founder generation

Cytosine base editing achieves C·G-to-T·A substitutions and can convert four codons(CAA/CAG/CGA/TGG)into STOP-codons(induction of STOP-codons,iSTOP)to knock out genes with reduced mosaicism.iSTOP enables direct phenotyping in founders’somatic cells,but it remains unknown whether this works in founders’germ cells so as to rapidly reveal novel genes for fertility.Here,we initially establish that iSTOP in mouse zygotes enables functional characterization of known genes in founders’germ cells:Cfap43-iSTOP male founders manifest expected sperm features resembling human“multiple morphological abnormalities of the flagella”syndrome(i.e.,MMAF-like features),while oocytes of Zp3-iSTOP female founders have no zona pellucida.We further illustrate iSTOP’s utility for dissecting the functions of unknown genes with Ccdc183,observing MMAF-like features and male infertility in Ccdc183-iSTOP founders,phenotypes concordant with those of Ccdc183-KO offspring.We ultimately establish that CCDC183 is essential for sperm morphogenesis through regulating the assembly of outer dynein arms and participating in the intra-flagellar transport.Our study demonstrates iSTOP as an efficient tool for direct reproductive disease modeling and phenotyping in germ cells of the founder generation,and rapidly reveals the essentiality of Ccdc183 in fertility,thus providing a time-saving approach for validating genetic defects(like nonsense mutations)for human infertility.

Pivotal role for long noncoding RNAs in zygotic genome activation in mice

Vertebrate life begins with fertilization,and then the zygote genome is activated after transient silencing,a process termed zygotic genome activation(ZGA).Despite its fundamental role in totipotency and the initiation of life,the precise mechanism underlying ZGA initiation remains unclear.The existence of minor ZGA implies the possible critical role of noncoding RNAs in the initiation of ZGA.Here,we delineate the expression profile of long noncoding RNAs(lncRNAs)in early mouse embryonic development and elucidate their critical role in minor ZGA.Compared with protein-coding genes(PCGs),lncRNAs exhibit a stronger correlation with minor ZGA.Distinct H3K9me3 profiles can be observed between lncRNA genes and PCGs,and the enrichment of H3K9me3 before ZGA might explain the suspended expression of major ZGA-related PCGs despite possessing PolII pre-configuration.Furthermore,we identified the presence of PolII-enriched MuERV-L around the transcriptional start site of minor ZGA-related lncRNAs,and these repeats are responsible for the activation of minor ZGA-related lncRNAs and subsequent embryo development.Our study suggests that MuERV-L mediates minor ZGA lncRNA activation as a critical driver between epigenetic reprogramming triggered by fertilization and the embryo developmental program,thus providing clues for understanding the regulatory mechanism of totipotency and establishing bona fide totipotent stem cells.

Lessons from expanded potential of embryonic stem cells:Moving toward totipotency

Embryonic stem cells possess fascinating capacity of self-renewal and developmental potential,leading to significant progress in understanding the molecular basis of pluripotency,disease modeling,and reprogramming technology.Recently,2-cell-like embryonic stem cells(ESCs)and expanded potential stem cells or extended pluripotent stem cells(EPSCs)generated from early-cleavage embryos display some features of totipotent embryos.These cell lines provide valuable in vitro models to study underlying principles of totipotency,cell plasticity,and lineage segregation.In this review,we summarize the current progress in this filed and highlight the application potentials of these cells in the future.

Generation of functional oligopeptides that promote osteogenesis based on unsupervised deep learning of protein IDRs

Deep learning(DL)is currently revolutionizing peptide drug development due to both computational advances and the substantial recent expansion of digitized biological data.However,progress in oligopeptide drug development has been limited,likely due to the lack of suitable datasets and difficulty in identifying informative features to use as inputs for DL models.Here,we utilized an unsupervised deep learning model to learn a semantic pattern based on the intrinsically disordered regions of~171 known osteogenic proteins.Subsequently,oligopeptides were generated from this semantic pattern based on Monte Carlo simulation,followed by in vivo functional characterization.A five amino acid oligopeptide(AIB5P)had strong bone-formation-promoting effects,as determined in multiple mouse models(e.g.,osteoporosis,fracture,and osseointegration of implants).Mechanistically,we showed that AIB5P promotes osteogenesis by binding to the integrinα5 subunit and thereby activating FAK signaling.In summary,we successfully established an oligopeptide discovery strategy based on a DL model and demonstrated its utility from cytological screening to animal experimental verification.

Bilineage embryo-like structure from EPS cells can produce live mice with tetraploid trophectoderm

Self-organized blastoids from extended pluripotent stem(EPs)cells possess enormous potential for investigating postimplantation embryo development and related diseases.However,the limited ability of postimplantation development of Eps-blastoids hinders its further application.In this study,single-cell transcriptomic analysis indicated that the“trophectoderm(TE)-like structure”of EPSblastoids was primarily composed of primitive endoderm(PrE)-related cells instead of TE-related cells.We further identified PrE-like cells in EPS cell culture that contribute to the blastoid formation with TE-like structure.Inhibition of PrE cell differentiation by inhibiting MEK signaling or knockout of Gata6 in EPS cells markedly suppressed EPS-blastoid formation.Furthermore,we demonstrated that blastocyst-like structures reconstituted by combining the EPs-derived bilineage embryo-like structure(BLEs)with either tetraploid embryos or tetraploid TE cells could implant normally and develop into live fetuses.In summary,our study reveals that TE improvement is critical for constructing a functional embryo using stem cells in vitro.

Digital light processing (DLP)-based (bio)printing strategies for tissue modeling and regeneration

Digital light processing(DLP)-based bioprinting technology has recently aroused considerable concerns as a strategy to deliver biomedical materials and/or specific cells to create sophisticated structures for various tissue modeling and regeneration.In this review,we display a concise introduction of DLP bioprinting,and a further discussion on the design and manufacture of DLP(bio)printer with varied bioinks and their biomedical applications toward drug screening,disease modeling,tissue repair,and regenerative medicine.Finally,the advantages,challenges,and perspectives of the DLP printing platforms are detailed.It is believed that DLP bioprinting will play a decisive role in the field of tissue model and regenerative medicine,mainly due to its time-efficient,higher resolution,and amenability to automation for various tissue needs.

Effect of SARS-CoV-2 infection in early pregnancy on placental development

Dear Editor,Since the COVID-19 pandemic, the potential risks associated with maternal SARS-CoV-2 infection and its effect on fetal development have been a subject of considerable public concern. Previous studies have shown that SARS-CoV-2 infection during pregnancy may increase the incidence of adverse outcomes.

RNA m^(6)A reader YTHDF2 facilitates precursor miR-126 maturation to promote acute myeloid leukemia progression

As the most common internal modification of mRNA,Ne-methyladenosine(m^(6)A)and its regulators modulate gene expression and play critical roles in various biological and patholog-ical processes including tumorigenesis.It was reported previously that m^(6)A methyltransferase(writer),methyltransferase-like 3(METTL3)adds m^(6)A in primary microRNAs(pri-miRNAs)and fa-cilitates its processing into precursor miRNAs(pre-miRNAs).However,it is unknown whether m^(6)A modification also plays a role in the maturation process of pre-miRNAs and(if so)whether such a function contributes to tumorigenesis.Here,we found that YTHDF2 is aberrantly overexpressed in acute myeloid leukemia(AML)patients,especially in relapsed patients,and plays an onco-genic role in AML.Moreover,YTHDF2 promotes expression of miR-126-3p(also known as miR-126,as it is the main product of precursor miR-126(pre-miR-126)),a miRNA that was reported as an oncomiRNA in AML,through facilitating the processing of pre-miR-126 into mature miR-126.Mechanistically,YTHDF2 recognizes m^(6)A modification in pre-miR-126 and recruits AGO2,a regulator of pre-miRNA processing,to promote the maturation of pre-miR-126.YTHDF2 posi-tively and negatively correlates with miR-126 and miR-126's downstream target genes,respec-tively,in AML patients,and forced expression of miR-126 could largely rescue YTHDF2/Ythdf2 depletion-mediated suppression on AML cell growth/proliferation and leukemogenesis,indi-cating that miR-126 is a functionally important target of YTHDF2 in AML.Overall,our studies not only reveal a previously unappreciated YTHDF2/miR-126 axis in AML and highlight the ther-apeutic potential of targeting this axis for AML treatment,but also suggest that m^(6)A plays a role in pre-miRNA processing that contributes to tumorigenesis.

Single-cell RNA Sequencing Reveals Sexually Dimorphic Transcriptome and Type 2 Diabetes Genes in Mouse Islet β Cells

Type 2 diabetes(T2D)is characterized by the malfunction of pancreaticβcells.Susceptibility and pathogenesis of T2D can be affected by multiple factors,including sex differences.However,the mechanisms underlying sex differences in T2D susceptibility and pathogenesis remain unclear.Using single-cell RNA sequencing(scRNA-seq),we demonstrate the presence of sexually dimorphic transcriptomes in mouseβcells.Using a high-fat diet-induced T2D mouse model,we identified sex-dependent T2D altered genes,suggesting sex-based differences in the pathological mechanisms of T2D.Furthermore,based on islet transplantation experiments,we found that compared to mice with sexmatched islet transplants,sex-mismatched islet transplants in healthy mice showed down-regulation of genes involved in the longevity regulating pathway ofβcells.Moreover,the diabetic mice with sex-mismatched islet transplants showed impaired glucose tolerance.These data suggest sexual dimorphism in T2D pathogenicity,indicating that sex should be considered when treating T2D.We hope that our findings could provide new insights for the development of precision medicine in T2D.

Genome transfer for the prevention of female infertility caused by maternal gene mutation

Poor oocyte quality is associated with early embryo developmental arrest and infertility.Maternal gene plays crucial roles in the regulation of oocyte maturation,and its mutation is a common cause of female infertility.However,how to improve oocyte quality and develop effective therapy for maternal gene mutation remains elusive.Here,we use Zar1 as an example to assess the feasibility of genome transfer to cure maternal gene mutationecaused female infertility.We first discover that cytoplasmic deficiency primarily leads to Zar1-null embryo developmental arrest by disturbing maternal transcript degradation and minor zygotic genome activation(ZGA)during the maternal-zygotic transition.We next perform genome transfer at the oocyte(spindle transfer or polar body transfer)and zygote(early pronuclear transfer or late pronuclear transfer)stages to validate the feasibility of preventing Zar1 mutationecaused infertility.We finally demonstrate that genome transfer either at the oocyte or at the early pronuclear stage can support normal preimplantation embryo development and produce live offspring.Moreover,those pups grow to adulthood and show normal fertility.Therefore,our findings provide an effective basis of therapies for the treatment of female infertility caused by maternal gene mutation.

Single-cell transcriptomics of cardiac progenitors reveals functional subpopulations and their cooperative crosstalk in cardiac repair

Dear Editor,Myocardial infarction is one of the leading causes of morbidity and mortality.Stem/progenitor cells therapy has emerged as a promising strategy for the cardiac repair,especially those derived from cardiac tissue,have attracted worldwide attention(Tompkins et al.,2018).However,challenges and controversies remain in characterizing functional progenitors and explaining their mechanisms of action.

Genetic lineage tracing identifies cardiac mesenchymal-to-adipose transition in an arrhythmogenic cardiomyopathy model

Arrhythmogenic cardiomyopathy(ACM)is one of the most common inherited cardiomyopathies,characterized by progressive fibrofatty replacement in the myocardium.However,the cellular origin of cardiac adipocytes in ACM remains largely unknown.Unraveling the cellular source of cardiac adipocytes in ACM would elucidate the underlying pathological process and provide a potential target for therapy.Herein,we generated an ACM mouse model by inactivating desmosomal gene desmoplakin in cardiomyocytes;and examined the adipogenic fates of several cell types in the disease model.The results showed that SOX9^(+),PDGFRa^(+),and PDGFRb^(+)mesenchymal cells,but not cardiomyocytes or smooth muscle cells,contribute to the intramyocardial adipocytes in the ACM model.Mechanistically,Bmp4 was highly expressed in the ACM mouse heart and functionally promoted cardiac mesenchymal-to-adipose transition in vitro.