Characterizing the tumor microenvironment at the single-cell level reveals a novel immune evasion mechanism in osteosarcoma

The immune microenvironment extensively participates in tumorigenesis as well as progression in osteosarcoma(OS).However,the landscape and dynamics of immune cells in OS are poorly characterized.By analyzing single-cell RNA sequencing(sc RNA-seq)data,which characterize the transcription state at single-cell resolution,we produced an atlas of the immune microenvironment in OS.The results suggested that a cluster of regulatory dendritic cells(DCs)might shape the immunosuppressive microenvironment in OS by recruiting regulatory T cells.We also found that major histocompatibility complex class I(MHC-I)molecules were downregulated in cancer cells.The findings indicated a reduction in tumor immunogenicity in OS,which can be a potential mechanism of tumor immune escape.Of note,CD24 was identified as a novel“don’t eat me”signal that contributed to the immune evasion of OS cells.Altogether,our findings provide insights into the immune landscape of OS,suggesting that myeloid-targeted immunotherapy could be a promising approach to treat OS.

Plant abiotic stress response and nutrient use efficiency

Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.

Traumatic brain injury stimulates sympathetic tone-mediated bone marrow myelopoiesis to favor fracture healing

Traumatic brain injury(TBI)accelerates fracture healing,but the underlying mechanism remains largely unknown.Accumulating evidence indicates that the central nervous system(CNS)plays a pivotal role in regulating immune system and skeletal homeostasis.However,the impact of CNS injury on hematopoiesis commitment was overlooked.Here,we found that the dramatically elevated sympathetic tone accompanied with TBI-accelerated fracture healing;chemical sympathectomy blocks TBIinduced fracture healing.TBI-induced hypersensitivity of adrenergic signaling promotes the proliferation of bone marrow hematopoietic stem cells(HSCs)and swiftly skews HSCs toward anti-inflammation myeloid cells within 14 days,which favor fracture healing.Knockout ofβ3-orβ2-adrenergic receptor(AR)eliminate TBI-mediated anti-inflammation macrophage expansion and TBIaccelerated fracture healing.RNA sequencing of bone marrow cells revealed that Adrb2 and Adrb3 maintain proliferation and commitment of immune cells.Importantly,flow cytometry confirmed that deletion ofβ2-AR inhibits M2 polarization of macrophages at 7th day and 14th day;and TBI-induced HSCs proliferation was impaired inβ3-AR knockout mice.Moreover,β3-andβ2-AR agonists synergistically promote infiltration of M2 macrophages in callus and accelerate bone healing process.Thus,we conclude that TBI accelerates bone formation during early stage of fracture healing process by shaping the anti-inflammation environment in the bone marrow.These results implicate that the adrenergic signals could serve as potential targets for fracture management.

LOWER TEMPERATURE 1 Enhances ABA Responses and Plant Drought Tolerance by Modulating the Stability and Localization of C2-Domain ABA-Related Proteins in Arabidopsis

Plasma membrane-associated abscisic acid(ABA)signal transduction is an integral part of ABA signaling.The C2-domain ABA-related(CAR)proteins play important roles in the recruitment of ABA receptors to the plasma membrane to facilitate ABA signaling.However,how CAR proteins are regulated remains unclear.In this study,we conducted a genetic screen for mutants with altered leaf transpiration and identified an uncharacterized protein,LOWER TEMPERATURE 1(LOT1),which regulates the dynamic localization and stability of CAR proteins.The lotimutant had a lower leaf temperature as compared with the wild type due to higher transpiration.We found that LOT1 physically interacts with CAR9,and ABA reduces LOT1-CAR9 interaction in the nucleus,likely via Ca^2+,resulting in increased localization of CAR9 to the plasma membrane.We further found that the stability of CAR9 is affected by LOT1 less CAR9 proteins were accumulated and more were ubiquitinated in lot1.While the lot1 car9 and/of f car9 mutants were hyposerisitive to ABA,the hyposensitive phenotype of loticould be rescued by CAR9 overexpression.Collectively,our study reveals that LOT1 regulates plant tolerance to drought stress by affecting ABA signaling through regulating the stability and dynamic localization of CAR9.

Arabidopsis EXTRA-LARGE G PROTEIN 1(XLG1) functions together with XLG2 and XLG3 in PAMP-triggered MAPK activation and immunity

Pattern-triggered immunity(PTI) is an essential strategy used by plants to deploy broad-spectrum resistance against pathogen attacks. Heterotrimeric G proteins have been reported to contribute to PTI.Of the three non-canonical EXTRA-LARGE G PROTEINs(XLGs) in Arabidopsis thaliana, XLG2 and XLG3 were shown to positively regulate immunity,but XLG1 was not considered to function in defense,based on the analysis of a weak xlg1 allele.In this study, we characterized the xlg1 xlg2 xlg3 triple knockout mutants generated from an xlg1 knockout allele. The strong xlg1 xlg2 xlg3 triple mutants compromised pathogen-associated molecular pattern(PAMP)-triggered activation of mitogen-activated protein kinases(MAPKs) and resistance to pathogen infection. The three XLGs interacted with MAPK cascade proteins involved in defense signaling, including the MAPK kinase kinases MAPKKK3 and MAPKKK5, the MAPK kinases MKK4 and MKK5, and the MAPKs MPK3 and MPK6. Expressing a constitutively active form of MKK4 restored MAPK activation and partially recovered the compromised disease resistance seen in the strong xlg1 xlg2 xlg3 triple mutant. Furthermore, mutations of all three XLGs largely restored the phenotype of the autoimmunity mutant bak1-interacting receptor-like kinase 1. Our study reveals that all three XLGs function redundantly in PAMP-triggered MAPK activation and plant immunity.

Sequential slip transfer of mixed-character dislocations across Σ3 coherent twin boundary in FCC metals: a concurrent atomistic-continuum study

Sequential slip transfer across grain boundaries(GB)has an important role in size-dependent propagation of plastic deformation in polycrystalline metals.For example,the Hall–Petch effect,which states that a smaller average grain size results in a higher yield stress,can be rationalised in terms of dislocation pile-ups against GBs.In spite of extensive studies in modelling individual phases and grains using atomistic simulations,well-accepted criteria of slip transfer across GBs are still lacking,as well as models of predicting irreversible GB structure evolution.Slip transfer is inherently multiscale since both the atomic structure of the boundary and the long-range fields of the dislocation pile-up come into play.In this work,concurrent atomistic-continuum simulations are performed to study sequential slip transfer of a series of curved dislocations from a given pile-up onΣ3 coherent twin boundary(CTB)in Cu and Al,with dominant leading screw character at the site of interaction.A Frank-Read source is employed to nucleate dislocations continuously.It is found that subject to a shear stress of 1.2 GPa,screw dislocations transfer into the twinned grain in Cu,but glide on the twin boundary plane in Al.Moreover,four dislocation/CTB interaction modes are identified in Al,which are affected by(1)applied shear stress,(2)dislocation line length,and(3)dislocation line curvature.Our results elucidate the discrepancies between atomistic simulations and experimental observations of dislocation-GB reactions and highlight the importance of directly modeling sequential dislocation slip transfer reactions using fully 3D models.

An Extension of the Win Theorem: Counting the Number of Maximum Independent Sets

Win proved a well-known result that the graph G of connectivity κ(G) withα(G) ≤κ(G) + k-1(k ≥ 2) has a spanning k-ended tree, i.e., a spanning tree with at most k leaves. In this paper, the authors extended the Win theorem in case when κ(G) = 1 to the following: Let G be a simple connected graph of order large enough such that α(G) ≤ k + 1(k ≥ 3) and such that the number of maximum independent sets of cardinality k + 1 is at most n-2k-2. Then G has a spanning k-ended tree.

Adenovirus-mediated tissue inhibitor of metalloproteinase-3 gene transfection inhibits rabbit intervertebral disc degeneration in vivo

The aim of this study was to investigate the inhibitory effects of recombinant adenovirus vector carrying tissue inhibitor of metalloproteinase-3(RAd-TIMP-3)against degeneration of rabbit intervertebral disc.Thirty Japanese white rabbits of 4 months old were randomly divided into 5 groups.Mild or moderate rabbit lumbar disc degeneration model was constructed with the controllable axial loading device by imposing 98 N pressure at the discs for 2 weeks.Various doses of virus were injected into the degenerated discs as follows:20μL of normal saline in group 1;20μL of RAd66(an empty adenovirus vector,1.0�1010 OPU/mL)in group 2;and 20,10,and 5μL of RAdTIMP-3(1.0�1010 OPU/mL)in groups 3,4,and 5,respectively.Two weeks after the injection,the discs were collected for investigations,including assessment of degeneration degrees according to the Thompson’s grading system,reverse-transcription polymerase chain reaction(RT-PCR)assay for TIMP-3 gene,Safranin O-Fast green staining,and immunohisto-chemical staining for TIMP-3 and type II collagen.According to Thompson’s criteria,the degeneration of groups 3,4,and 5,especially group 3,was alleviated as compared with groups 1 and 2.RT-PCR revealed that the expression of TIMP-3 in groups 3,4,and 5,especially in group 3,was significantly enhanced as compared with group 1(P<0.01).Both Safranin O-Fast green staining and type II collagen staining demonstrated better reserved integrity of disc matrix in groups 3,4,and 5 than in groups 1 and 2.TIMP-3 staining exhibited an obvious increase of positive-staining rate in groups 3,4,and 5 as compared with group 1.The positive-staining rate in group 3(79.42%�1.35%)was about 3 times that of group 1(25.47%�5.46%,P<0.01).RAdTIMP-3 can effectively protect the matrix of rabbit intervertebral disc against overloading-induced degeneration in a dose-dependent manner,resulting in the alleviation of disc degeneration.