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Cao, M.

Publications and source records attributed to Cao, M..

89 records · Page 5Linked to original sources

Luteolin transforms the BMDM polarity to regulate the expression of inflammatory factors

ABSTRACTMacrophage are indispensable regulator cells in inflammatory response. Macrophage polarization and its secreted inflammatory factors have affinity with the outcomes of inflammation. Luteolin, a flavonoid abundant in plants has anti-inflammatory activity, but whether luteolin can manipulate M1/M2 polarization of BMDM to suppress inflammation is still veiled. The purpose of this study was to observe the effects of luterolin on the polarity of BMDM derived from C57BL/6 mice and the expression of inflammatory factors, to explore the mechanism of luteolin regulating the BMDM polarity. M1-polarized BMDM were induced by LPS+IFN-γ, M2-polarization were stimulated with IL-4. BMDM morphology was observed by laser confocal microscopy; levels of BMDM differentiation and CD11c or CD206 on membrane surface were assessed by FCM; mRNA and protein of M1/M2-type inflammatory factors were performed by qPCR and ELISA, respectively; the expression of p-STAT1 and p-STAT6 protein pathways was detected by Western-blotting. The isolated mouse bone marrow cells were successfully differentiated into BMDM, LPS+IFN-γ induced BMDM M1-phenotype polarization, and IL-4 induced its M2-phenotype polarization. After M1-polarized BMDM treated with luteolin, M1-type pro-inflammatory factors including IL-6, TNF-α□iNOS, CD86 were down-regulated while M2-type anti-inflammatory factors including IL-10, Arg1, CD206 were up-regulated; the expression of M1-type surface marker CD11c decreased, nevertheless, M2-type marker CD206 increased; levels of inflammatory signaling protein p-STAT1 and p-STAT6 were attenuated and enhanced respectively. Our study suggests luteolin may transform BMDM polarity through p-STAT1/6 to regulate the expression of inflammatory mediators, thereby inhibiting inflammation. Naturally occurring luteolin hold promise as an anti-inflammatory and immunomodulatory agent.View Full Text

immunology↗

Nonspecific Cleavages Arising from Reconstitution of Trypsin under Mildly Acidic Conditions

Tryptic digestion of proteins followed by liquid chromatography with tandem mass spectrometry analysis is an extensively used approach in proteomics research and biopharmaceutical product characterization, owing to the high level of cleavage fidelity produced with this technique. However, nonspecific trypsin cleavages have been frequently reported and shown to be related to a number of digestion conditions and predigestion sample treatments. In this work, we reveal that, for a number of commercial trypsins, reconstitution and storage conditions can have a significant impact on the occurrence of trypsin nonspecific cleavages. We analyzed the tryptic digestion of a variety of biotherapeutics, using trypsins reconstituted under different conditions. The results indicate that, for many commercial trypsins, commonly recommended reconstitution/storage conditions (mildly acidic, e.g., 50 mM acetic acid, 1 mM HCl) can actually promote nonspecific trypsin activities, which are time dependent and can be as high as 20% in total relative abundance. In contrast, using water for reconstitution and storage can effectively limit nonspecific cleavages to 1%. Interestingly, the performances of different commercial trypsins were found to be quite distinct in their levels of nonspecific cleavages and responses to the two reconstitution conditions. Our findings demonstrate the importance of choosing the appropriate trypsin for tryptic digestion and the necessity of assessing the impact of trypsin reconstitution and storage on nonspecific cleavages. We advocate for manufacturers of commercial trypsins to reevaluate manufacturing processes and reconstitution/storage conditions to provide good cleavage specificity.

biochemistry↗

Renewable Fatty Acid Ester Production in Clostridium

Production of renewable chemicals through biological routes is considered as an urgent solution for fossil energy crisis. However, endproduct toxicity inhibits microbial performance and is a key bottleneck for biochemical production. To address this challenge, here we report an example of biosynthesis of high-value and easy-recoverable derivatives to alleviate endproduct toxicity and enhance bioproduction efficiency. By leveraging the natural pathways in solventogenic clostridia for co-producing acyl-CoAs, acids and alcohols as precursors, through rational screening for host strains and enzymes, systematic metabolic engineering-- including rational organization of ester-synthesizing enzymes inside of the cell, and elimination of putative prophages, we developed strains that can produce 20.3 g/L butyl acetate and 1.6 g/L butyl butyrate respectively, which were both the unprecedented levels in microbial hosts. Techno-economic analysis indicated a production cost of $986 per metric tonne for butyl acetate production from corn stover comparing to the market price of $1,200-1,400 per metric tonne of butyl acetate, suggesting the economic competitiveness of our developed bioprocess. Our principles of selecting the most appropriate host for specific bioproduction and engineering microbial chassis to produce high-value and easy-separable endproducts are highly applicable to other bioprocesses, and could lead to breakthroughs in biofuel/biochemical production and general bioeconomy.

bioengineering↗

Foundation species across a latitudinal gradient in China

AbstractFoundation species play important roles in structuring forest communities and ecosystems. Foundation species are difficult to identify without long-term observations or experiments and their foundational roles rarely are identified before they are declining or threatened. We used new statistical criteria based on size-frequency distributions, species diversity, and spatial codispersion among woody plants to identify potential ("candidate") foundation species in 12 large forest dynamics plots spanning 26 degrees of latitude in China. We used these data to identify a suite of candidate foundation species in Chinese forests; test the hypothesis that foundation woody plant species are more frequent in the temperate zone than in the tropics; and compare these results with comparable data from the Americas to suggest candidate foundation genera in Northern Hemisphere forests. We identified more candidate foundation species in temperate plots than in subtropical or tropical plots, and this relationship was independent of the latitudinal gradient in overall species richness. Two species of Acer, the canopy tree Acer ukurunduense and the shrubby treelet Acer barbinerve were the only two species that met both criteria in full to be considered as candidate foundation species. When we relaxed the diversity criteria, Acer, Tilia, and Juglans spp., and Corlyus mandshurica were frequently identified as candidate foundation species. In tropical plots, the tree Mezzettiopsis creaghii and the shrubs or treelets Aporusa yunnanensis and Ficus hispida had some characteristics associated with foundation species. Species diversity of co-occurring woody species was negatively associated with basal area of candidate foundation species more frequently at 5- and 10-m spatial grains (scale) than at a 20-m grain. Conversely, Bray-Curtis dissimilarity was positively associated with basal area of candidate foundation species more frequently at 5-m than at 10- or 20-m grains. Our data support the hypothesis that foundation species should be more common in temperate than in tropical or boreal forests, and suggest that in the Northern Hemisphere that Acer be investigated further as a foundation tree genus.

ecology↗

Functional Identification of Specialized Basal Ganglia Circuits that Regulate Vocal Motor Sequences

Disruption of the transcription factor FoxP2, which is enriched in the basal ganglia, impair vocal development in humans and songbirds. The basal ganglia are essential for the selection and sequencing of motor actions, but the circuit mechanisms governing accurate sequencing of learned vocalizations are unknown. Here, we show expression of FoxP2 in the basal ganglia is vital for the fluent initiation and termination of birdsong, and the maintenance of song syllable sequencing in adulthood. Knockdown of FoxP2 imbalances dopamine receptor expression across striatal direct-like and indirect-like pathways, suggesting a role of dopaminergic signaling in regulating vocal-motor sequencing. Confirming this prediction, we show that phasic dopamine activation, and not inhibition, during singing drives repetition of song syllables, thus also impairing fluent initiation and termination of birdsong. These findings demonstrate discrete circuit origins for the dysfluent repetition of vocal elements, a phenotype commonly observed in speech disorders.

neuroscience↗

Absence of Sac2/INPP5F enhances the phenotype of a Parkinson's disease mutation of synaptojanin 1

Many genes whose mutations cause, or increase the risk of, Parkinsons disease (PD) have been identified. An inactivating mutation (R258Q) in the Sac inositol phosphatase domain of synaptojanin 1 (SJ1/PARK20), a phosphoinositide phosphatase implicated in synaptic vesicle recycling, results in PD. The gene encoding Sac2/INPP5F, another Sac domain containing protein, was identified as a PD risk locus by GWAS. Knock-In mice carrying the SJ1 patient mutation (SJ1RQKI) exhibit PD features, while Sac2 knockout mice (Sac2KO) do not have obvious neurological defects. We report a "synthetic" effect of the SJ1 mutation and the KO of Sac2 in mice. Most mice with both mutations died perinatally. The occasional survivors had stunted growth, died within 3 weeks, and showed abnormalities of striatal dopaminergic nerve terminals at an earlier stage than SJ1RQKI mice. The abnormal accumulation of endocytic factors observed at synapses of cultured SJ1RQKI neurons was more severe in double mutant. Our results suggest that SJ1 and Sac2 have partially overlapping functions and are consistent with a potential role of Sac2 as a PD risk gene.

neuroscience↗

Genomic predictive ability for foliar nutritive traits in perennial ryegrass

Forage nutritive value impacts animal nutrition, which underpins livestock productivity, reproduction and health. Genetic improvement for nutritive traits has been limited, as they are typically expensive and time-consuming to measure through conventional methods. Genomic selection is appropriate for such complex and expensive traits, enabling cost-effective prediction of breeding values using genome-wide markers. The aims of the present study were to assess the potential of genomic selection for a range of nutritive traits in a multi-population training set, and to quantify contributions of genotypic, environmental and genotype-by-environment (G x E) variance components to trait variation and heritability for nutritive traits. The training set consisted of a total of 517 half-sibling (half-sib) families, from five advanced breeding populations, evaluated in two distinct New Zealand grazing environments. Autumn-harvested samples were analyzed for 18 nutritive traits and maternal parents of the half-sib families were genotyped using genotyping-by-sequencing. Significant (P<0.05) genotypic variation was detected for all nutritive traits and genomic heritability (h2g) was moderate to high (0.20 to 0.74). G x E interactions were significant and particularly large for water soluble carbohydrate (WSC), crude fat, phosphorus (P) and crude protein. GBLUP, KGD-GBLUP and BayesC genomic prediction models displayed similar predictive ability, estimated by 10-fold cross validation, for all nutritive traits with values ranging from r = 0.16 to 0.45 using phenotypes from across two environments. High predictive ability was observed for the mineral traits sulphur (0.44), sodium (0.45) and magnesium (0.45) and the lowest values were observed for P (0.16), digestibility (0.22) and high molecular weight WSC (0.23). Predictive ability estimates for most nutritive traits were retained when marker number was reduced from 1 million to as few as 50,000. The moderate to high predictive abilities observed suggests implementation of genomic selection is feasible for most of the nutritive traits examined. For traits with lower predictive ability, multi-trait genomic prediction approaches that exploit the strong genetic correlations observed amongst some nutritive traits may be useful. This appears to be particularly important for WSC, considered one of the primary constituent of nutritive value for forages.

plant biology↗

Control strategies for the timing of intracellular events

While the timing of intracellular events is essential for many cellular processes, gene expression inside a cell can exhibit substantial cell-to-cell variability, raising the question of how cells ensure precision in the event timing despite such stochasticity. We address this question by analyzing a biologically reasonable model of gene expression in the context of first passage time (FPT), focusing on two experimentally measurable statistics: mean FPT (MFPT) and timing variability (TV). We show that: (1) transcriptional burst size (BS) and burst frequency (BF) can minimize the TV; (2) translational BS monotonically reduces the MFPT to a nonzero low bound and can minimize the TV; (3) the timescale of promoter kinetics can minimize both the MFPT and the TV, depending on the ratio of the off-switching rate over the on-switching rate; and (4) positive feedback regulation of any form can all minimize the TV, whereas negative feedback regulation of transcriptional BF or BS always enhances the TV. These control strategies can have broad implications for diverse cellular processes relying on precise temporal triggering of events.

systems biology↗

Genotyping-by-sequencing based cytoplasmic markers underpin population structural variation of perennial ryegrass

Chloroplast and mitochondrial genomes provide unique information in studying plant populations because cytoplasmic genes exhibit a different mode of inheritance and a different rate of gene mutation compared to nuclear genes. Despite this, cytoplasmic genomic contributions to plant population performance are largely unexplored because few methods are available to characterize and evaluate cytoplasmic genome-wide variations. Here we have developed cytoplasmic markers based on genotyping-by-sequencing (GBS), which enable us to characterize thousands of samples, to survey gene variants across cytoplasmic genomes, and to monitor within-population variations of chloroplast or mitochondrial origin. Using these cytoplasmic genome-wide markers we have found that within-population differentiations are evident in ryegrass (Lolium perenne), beyond the explanation of nuclear markers. Moreover, chloroplast and mitochondrial variations exhibit different patterns, with mitochondrial markers more readily reflecting the maternal origins. Application of GBS-based cytoplasmic markers should facilitate quantifying the contribution of cytoplasmic inheritance to plant performance through selective breeding or under natural selection pressure.

genetics↗

Isolation and characterization of rare circulating autoantibody-producing cells from patients with muscle-specific kinase myasthenia gravis

Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by muscle weakness and caused by autoantibodies that bind to functional membrane proteins at the neuromuscular junction. Most patients have autoantibodies to the acetylcholine receptor (AChR), but a subset of patients instead have autoantibodies to muscle specific tyrosine kinase (MuSK). MuSK is an essential component of the Agrin/Lipoprotein receptor-related protein 4(LRP4)/MuSK/downstream of tyrosine kinase 7 (DOK7) pathway that is responsible for synaptic differentiation, including clustering of AChRs at the neuromuscular junction, both during development and in adult muscle. Nerve-released Agrin binds to LRP4 which then binds to MuSK, stimulating autophosphorylation and recruitment of DOK7 to complete the membrane component of the pathway. Serum-derived IgG4 subclass MuSK autoantibodies prevent the binding of LRP4 to MuSK, subsequently impairing autophosphorylation, resulting in the loss of Agrin-induced AChR clustering in the mouse myotube-forming C2C12 line. Although this autoimmune mechanism appears well understood, MuSK autoantibodies from patients are polyclonal. Most are IgG4 but IgG1, 2 and 3 are also present and can achieve similar results on AChR clustering. In addition, most bind the first Ig-like domain in MuSK, however some patients harbor serum autoantibodies that recognize other domains in MuSK. We sought to establish individual MuSK IgG clones so that the disease mechanisms could be better understood. We isolated MuSK autoantibody-expressing B cells from MuSK MG patients with a fluorescent-tagged MuSK antigen multimer and generated a panel of human monoclonal autoantibodies (mAbs) from these cells. We produced 77 mAbs from single B cells collected from six MuSK MG patients. Here we focused on three highly specific mAbs that bound quantitatively to MuSK in solution, to MuSK-expressing HEK cells and at mouse neuromuscular junctions where they co-localized with AChRs. These three IgG isotype mAbs (two IgG4 and one IgG3 subclass) recognized the Ig-like domain 2 of MuSK. The three MuSK mAbs inhibited Agrin induced-AChR clustering in C2C12 myotubes, but intriguingly, they enhanced rather than inhibited MuSK phosphorylation. This approach for ex vivo isolation of MuSK MG autoantibody-producing cells and production of human recombinant mAbs has identified distinct autoantibody specificities and likely divergent effector mechanisms. Collectively, these findings will enable a better understanding of MuSK autoantibody-mediated pathology.

immunology↗

Modeling motor neuron resilience in ALS using stem cells

Oculomotor neurons, which regulate eye movement, are resilient to degeneration in the lethal motor neuron disease amyotrophic lateral sclerosis (ALS). It would be highly advantageous if motor neuron resilience could be modeled in vitro. Towards this goal, we generated a high proportion of oculomotor neurons from mouse embryonic stem cells through temporal overexpression of Phox2a in neuronal progenitors. We demonstrate, using immunocytochemistry and RNA sequencing, that in vitro generated neurons are bona fide oculomotor neurons based on their similarity to their in vivo counterpart in rodent and man. We also show that in vitro generated oculomotor neurons display a robust activation of survival-promoting Akt signaling and are more resilient to the ALS-like toxicity of kainic acid than spinal motor neurons. Thus, we can generate bona fide oculomotor neurons in vitro which display a resilience similar to that seen in vivo.

neuroscience↗

Inducible formation of leading cells driven by CD44 switching gives rise to collective invasion

Collective invasion into adjacent tissue is a hallmark of luminal breast cancer, with about 20% of cases that eventually undergo metastasis. It remained unclear how less aggressive luminal-like breast cancer transit to invasive cancer. Our study revealed that CD44hi cancer cells are the leading subpopulation in collective invading cancer cells, which could efficiently lead the collective invasion of CD44lo/follower cells. CD44hi/leading subpopulation showed specific gene signature of a cohort of hybrid epithelial/mesenchymal state genes and key functional co-regulators of collective invasion, which was distinct from CD44lo/follower cells. However, the CD44hi/leading cells, in partial-EMT state, were readily switching to CD44lo phenotype along with collective movements and vice versa, which is spontaneous and sensitive to tumor microenvironment. The CD44lo-to-CD44hi conversion is accompanied with a shift of CD44s-to-CD44v, but not corresponding to the conversion of non-CSC-to-CSC. Therefore, the CD44hi leader cells are not a stable subpopulation in breast tumors. This plasticity and ability to generate CD44hi carcinoma cells with enhanced invasion-initiating powers might be responsible for the transition from in situ to invasive behavior of luminal-type breast cancer.\n\nSignificanceNow, the mechanisms involved in local invasion and distant metastasis are still unclear. We identified a switch of CD44 that drives leader cell formation during collective invasion in luminal breast cancer. We provided evidence that interconversions between low and high CD44 states occur frequently during collective invasion. Furthermore, these findings demonstrated that the CD44hi/leader cells featuring partial EMT are inducible and attainable in response to tumor microenvironment. The CD44lo cancer cells are plastic that readily shift to CD44hi state, accompanied with shifts of CD44s-to-CD44v, thereby increasing tumorigenic and malignant potential. There are many \"non-invasiveness\" epithelial/follower cells with reversible invasive potential within an individual tumor, that casting some challenges on molecular targeting therapy.

cancer biology↗

Heterogeneity of transposon expression and activation of the repressive network in human fetal germ cells

Epigenetic resetting in germ cells during development leads to the de-repression of transposable elements (TEs). piRNAs protect fetal germ cells from potentially harmful TEs by targeted destruction of mRNA and deposition of repressive epigenetic marks. Here we provide the first evidence for an active piRNA pathway and TE repression in germ cells of human fetal testis. We identify pre-pachytene piRNAs with features of secondary amplification that map most abundantly to L1 family TEs. We find that L1-ORF1p expression is heterogeneous in fetal germ cells, peaks at mid-gestation and declines concomitantly with increasing levels of piRNAs and H3K9me3, as well as nuclear localization of HIWI2. Surprisingly, following this decline, the same cells with accumulation of L1-ORF1p display highest levels of HIWI2 and H3K9me3, whereas L1-ORF1p low cells are also low in HIWI2 and H3K9me3. Conversely, earlier in development, the germ cells lacking L1-ORF1p express high levels of the chaperone HSP90a. We propose that a subset of HSP90a-armed germ cells resists L1 expression, whereas only those vulnerable L1-expressing germ cells activate the PIWI-piRNA repression pathway which leads to epigenetic silencing of L1 via H3K9me3.

developmental biology↗

Spatial transcriptomics and in silico random pooling identify novel dopamine neuron subtype markers

Defining transcriptional profiles of substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) dopamine neurons is critical to understanding their differential vulnerability in Parkinsons Disease (PD). Here, we determine transcriptomes of human SNc and VTA dopamine neurons using LCM-seq on a large sample cohort. We apply a bootstrapping strategy as sample input to DESeq2 and identify 33 stably differentially expressed genes (DEGs) between these two subpopulations. We also compute a minimal sample size for identification of stable DEGs, which highlights why previous reported profiles from small sample sizes display extensive variability. Network analysis reveal gene interactions unique to each subpopulation and highlight differences in regulation of mitochondrial stability, apoptosis, neuronal survival, cytoskeleton regulation, extracellular matrix modulation and well as synapse integrity, which could explain the relative resilience of VTA dopamine neurons. Analysis of PD tissues showed that while identified stable DEGs can distinguish the subpopulations also in disease, the SNc markers SLIT1 and ATP2A3 were downregulated and thus appears to be biomarkers of disease. In summary, our study identifies human SNc and VTA marker profiles, which will be instrumental for studies aiming to modulate dopamine neuron resilience and to validate cell identity of stem cell-derived dopamine neurons.

neuroscience↗

A Basal Ganglia Circuit Sufficient to Guide Birdsong Learning

Learning complex vocal behaviors, like speech and birdsong, is thought to rely on continued performance evaluation. Whether candidate performance evaluation circuits in the brain are sufficient to guide vocal learning is not known. Here, we test the sufficiency of VTA projections to the vocal basal ganglia (Area X) in singing zebra finches, a songbird species that learns to produce a complex and stereotyped multi-syllabic courtship song during development. We optogenetically manipulate VTA axon terminals in singing birds contingent on how the pitch of individual song syllables are naturally performed. We find that optical excitation and inhibition of VTA terminals have opponent effects on future performances of targeted song syllables and are each sufficient to reliably guide learned changes in song, consistent with positive and negative reinforcement of performance outcomes. These findings define a central role for reinforcement mechanisms in learning vocalizations and provide the first demonstration of minimal circuit elements for learning vocal behaviors.

neuroscience↗

Cloning, Molecular Evolution And Functional Characterization Of ZmbHLH16, The Maize Ortholog Of OsTIP2 (OsbHLH142)

Abstract Basic helix-loop-helix (bHLH) transcription factors play key roles in plant male reproduction. More than 14 bHLH proteins related to pollen development have been cloned from rice and Arabidopsis. However, little is known about the role of the bHLH family in maize microspore development. In this study, the bHLH transcription factor ZmbHLH16 was cloned. ZmbHLH16 shares high similarity with the OsTIP2 (OsbHLH142) protein, a master regulator of the developmental coordination of male reproduction in rice. Expression characterization analysis showed that ZmbHLH16 is preferentially expressed in male reproductive organs and is located in the nucleus. Through nucleotide variation analysis, 36 polymorphic sites in ZmbHLH16, including 23 SNPs and 13 InDels, were detected among 78 maize inbred lines. Neutrality tests and linkage disequilibrium analysis showed that ZmbHLH16 experienced no significant evolutionary pressure. A yeast one-hybrid experiment showed that the first 80 residues in the N-terminus of ZmbHLH16 had transactivation activity, whereas the full length did not. To identify potential ZmbHLH16 interactors, 395 genes that shared similar expression patterns in a genome-wide search were obtained through coexpression analysis. Among these genes, the transcription factor ZmbHLH51 had an expression pattern and subcellular localization similar to those of ZmbHLH16. The interaction between ZmbHLH51 and ZmbHLH16 was verified in yeast cells. In addition to the typical bHLH domain, other regions of ZmbHLH16 were necessary and adequate for its heterodimerization with ZmbHLH51. Our results contribute to a solid foundation for further understanding the functions and mechanisms of ZmbHLH16.

molecular biology↗

α7 nicotinic acetylcholine receptor signalling modulates the inflammatory and iron homeostasis in fetal brain microglia

Neuroinflammation in utero may result in life-long neurological disabilities. Microglia play a pivotal role, but the mechanisms are poorly understood. No early postnatal treatment strategies exist to enhance neuroprotective potential of microglia. We hypothesized that agonism on 7 nicotinic acetylcholine receptor (7nAChR) in fetal microglia will augment their neuroprotective transcriptome profile, while the antagonistic stimulation of 7nAChR will achieve the opposite. Using an in vivo - in vitro model of developmental programming of neuroinflammation induced by lipopolysaccharide (LPS), we validated this hypothesis in primary fetal sheep microglia cultures re-exposed to LPS in presence of a selective 7nAChR agonist or antagonist. Our RNAseq and protein level findings show that a pro-inflammatory microglial phenotype acquired in vitro by LPS stimulation is reversed with 7nAChR agonistic stimulation. Conversely, antagonistic 7nAChR stimulation potentiates the pro-inflammatory microglial phenotype. Surprisingly, under conditions of LPS double-hit an interference of a postulated 7nAChR - ferroportin signaling pathway may impede this mechanism. These results suggest a therapeutic potential of 7nAChR agonists in early re-programming of microglia in neonates exposed to in utero inflammation via an endogenous cerebral cholinergic anti-inflammatory pathway. Future studies will assess the role of interactions between inflammation-triggered microglial iron sequestering and 7nAChR signaling in neurodevelopment.

neuroscience↗