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Xiaoyu Hu

Publications and source records attributed to Xiaoyu Hu.

15 recordsLinked to original sources
PubMed2026

A massively parallel CRISPR-based screening platform for modifiers of neuronal depolarization.

Understanding the complex interplay between gene expression and neuronal activity is crucial for unraveling the molecular mechanisms underlying cognitive function and neurological disorders. Here, we developed pooled screens using CRISPR interference (CRISPRi) and the fluorescent calcium integrator CaMPARI2 to evaluate genetic modifiers of neuronal depolarization. Using this screening method, we evaluated 1343 genes for their effect on depolarization in a human iPSC-derived neuron model, revealing potential links to neurodegenerative and neurodevelopmental disorders. These genes include known regulators of neuronal excitability, such as TARPs and ion channels, as well as genes associated with autism spectrum disorder and Alzheimer's disease not previously described to affect neuronal depolarization. This CRISPRi-based screening platform offers a versatile tool to uncover molecular mechanisms controlling neuronal function in health and disease.

Humans↗
PubMed2025

A Massively Parallel CRISPR-Based Screening Platform for Modifiers of Neuronal Activity.

Understanding the complex interplay between gene expression and neuronal activity is crucial for unraveling the molecular mechanisms underlying cognitive function and neurological disorders. Here, we developed pooled screens for neuronal activity, using CRISPR interference (CRISPRi) and the fluorescent calcium integrator CaMPARI2. Using this screening method, we evaluated 1343 genes for their effect on excitability in human iPSC-derived neurons, revealing potential links to neurodegenerative and neurodevelopmental disorders. These genes include known regulators of neuronal excitability, such as TARPs and ion channels, as well as genes associated with autism spectrum disorder and Alzheimer's disease not previously described to affect neuronal excitability. This CRISPRi-based screening platform offers a versatile tool to uncover molecular mechanisms controlling neuronal activity in health and disease.

Journal Article↗
PubMed2006

IFN-gamma suppresses IL-10 production and synergizes with TLR2 by regulating GSK3 and CREB/AP-1 proteins.

The control of IL-10 production and mechanisms that mediate synergy between IFN-gamma and TLR ligands are not well understood. We report that IFN-gamma augments induction of TNFalpha by TLR ligands, immune complexes, and zymosan by suppressing IL-10 production and thereby interrupting Stat3-mediated feedback inhibition. IFN-gamma altered TLR2-induced signal transduction by increasing GSK3 activity and suppressing MAPK activation, leading to diminished IL-10 production. Inhibition of GSK3 or ablation of the GSK3beta gene ameliorated TLR2-induced peritonitis and arthritis. IFN-gamma suppressed the activity of CREB and AP-1, transcription factors that induce IL-10 expression and are regulated in part by MAPKs and GSK3. These results yield insight into mechanisms by which IFN-gamma regulates IL-10 production and TLR2-mediated inflammatory responses and identify inhibition of CREB and AP-1 as part of the macrophage response to IFN-gamma. GSK3 and CREB/AP-1 are key players in integrating IFN-gamma and TLR2 responses in innate immunity and inflammation.

Animals↗
PubMed2005

The GRIP1:IRF3 interaction as a target for glucocorticoid receptor-mediated immunosuppression.

Glucocorticoids dramatically inhibit cytokine and chemokine production. They act through the glucocorticoid receptor (GR), a ligand-dependent transcription factor that binds to and represses activities of other DNA-bound regulators, activator protein 1 and nuclear factor kappaB, utilizing a p160 GRIP1 as a corepressor. A yeast two-hybrid screen with the GRIP1 corepression domain (RD) yielded interferon (IFN) regulatory factor (IRF)3-a downstream effector of Toll-like receptors (TLR) 3/4 and an essential activator of several IFN and chemokine genes. We defined the GRIP1:IRF3 interface and showed that endogenous GRIP1 and IRF3 interact in mammalian cells. Interestingly, GR and IRF3 competed for GRIP1 binding; GR activation or GRIP1 knockdown in macrophages blocked whereas GRIP1 overexpression rescued IRF3-dependent gene expression. GR interference persisted in MyD88- and IFNA receptor-deficient mice, suggesting a specific disruption of TLR3-IRF3 pathway, not of autocrine IFN signaling. Finally, IRF3-stimulated response elements were necessary and sufficient for TLR3-dependent induction and glucocorticoid inhibition. Thus, GRIP1 plays a cofactor role in innate immunity. Competition with GR for GRIP1 antagonizes IRF3-mediated transcription, identifying the GRIP1:IRF3 interaction as a novel target for glucocorticoid immunosuppression.

Adaptor Proteins, Signal Transducing↗
PubMed2005

IFN-gamma-primed macrophages exhibit increased CCR2-dependent migration and altered IFN-gamma responses mediated by Stat1.

Priming of macrophages with IFN-gamma increases cellular responsiveness to inflammatory stimuli, including IFN-gamma itself. We described previously that priming with subactivating concentrations of IFN-gamma increased Stat1 expression and resulted in enhanced activation of Stat1 and of a subset of IFN-gamma-responsive genes when primed macrophages were restimulated with low doses of IFN-gamma. In this study, we determined the effects of IFN-gamma priming on the macrophage transcriptome and on transcriptional responses to high saturating concentrations of IFN-gamma. At baseline, primed macrophages expressed a small subset of IFN-gamma-inducible genes, including CCR2, and exhibited increased migration in response to CCL2. Activation of gene expression by high concentrations of IFN-gamma was altered in primed macrophages, such that activation of a subset of IFN-gamma-inducible genes was attenuated. A majority of genes in this "less induced" category corresponded to genes that are induced by IFN-gamma via Stat1-independent but Stat3-dependent pathways and have been implicated in inflammatory tissue destruction. One mechanism of attenuation of gene expression was down-regulation of Stat3 function by increased levels of Stat1. These results reveal that priming enhances migration to inflammatory chemokines and identify IFN-gamma-inducible genes whose expression is attenuated by high levels of Stat1. The increase in Stat1 expression during priming provides a mechanism by which physiological regulation of the relative abundance of Stat1 and Stat3 impacts on gene expression. Our results also suggest that, in addition to inducing hypersensitivity to inflammatory stimuli, IFN priming delivers a homeostatic signal by attenuating IFN-gamma induction of certain tissue-destructive genes.

Blood Cells↗
PubMed2005

Homeostatic role of interferons conferred by inhibition of IL-1-mediated inflammation and tissue destruction.

In addition to their well known immune and proinflammatory activities, IFNs possess homeostatic functions that limit inflammation and tissue destruction in a variety of conditions such as arthritis, osteolysis, and multiple sclerosis. The mechanisms underlying the homeostatic actions of IFNs are not well understood. We report here that both type I and type II IFNs (IFN-alpha, IFN-beta, and IFN-gamma, respectively) suppressed a broad range of proinflammatory and tissue-destructive activities of IL-1, including induction of inflammatory mediators, production of matrix metalloproteinases, macrophage tissue invasion, and cartilage degradation. IFN-alpha attenuated IL-1-mediated cell recruitment in vivo. IFNs completely suppressed the activation of IL-1 signal transduction pathways in macrophages. The mechanism of IFN-mediated inhibition of IL-1 action and signaling was modulation of IL-1R expression, which was also observed in vivo. IFN-gamma-mediated down-regulation of IL-1R type I expression was dependent on Stat1, a transcription factor typically considered to be a key mediator of macrophage activation by IFNs. These results identify cellular and molecular mechanisms that contribute to the homeostatic role of IFNs in limiting inflammation and associated tissue destruction.

Animals↗
PubMed2005

Advanced provision of emergency contraception to postnatal women in China makes no difference in abortion rates: a randomized controlled trial.

Emergency contraception (EC) prevents pregnancy, and it has been suggested that widespread use could reduce abortion rates; however, the use is limited. Providing EC in advance of need increases use, but there is no direct evidence that it reduces unintended pregnancy. In a randomized controlled trial of 2000 women after childbirth in Shanghai, all women not wishing to use hormonal contraception or an intrauterine device (IUD) were given a supply of condoms. Those in the intervention group also received three courses of mifepristone 10 mg with instructions for use as EC. Follow-up was by telephone at 16, 32 and 52 weeks. Over 88% of women in both groups completed 1 year of follow-up. Women with a supply of EC were more than twice as likely to use it, and to use it more than once (p<.001 for both) than women without a supply. There was no difference in pregnancy rates at 1 year (38/832 vs. 32/817). EC was not used in 89% of conception cycles, as women did not recognize the need for it. Increased use of EC may not reduce abortion rates.

Abortion, Induced↗
PubMed2004

Human Zwint-1 specifies localization of Zeste White 10 to kinetochores and is essential for mitotic checkpoint signaling.

Chromosome segregation in mitosis is orchestrated by dynamic interaction between spindle microtubules and the kinetochore, a multiprotein complex assembled onto centromeric DNA of the chromosome. Here we show that Zwint-1 is required and is sufficient for kinetochore localization of Zeste White 10 (ZW10) in HeLa cells. Zwint-1 specifies the kinetochore association of ZW10 by interacting with its N-terminal domain. Suppression of synthesis of Zwint-1 by small interfering RNA abolishes the localization of ZW10 to the kinetochore, demonstrating the requirement of Zwint-1 for ZW10 kinetochore localization. In addition, depletion of Zwint-1 affects no mitotic arrest but causes aberrant premature chromosome segregation. These Zwint-1-suppressed cells display chromosome bridge phenotype with sister chromatids inter-connected. Moreover, Zwint-1 is required for stable association of CENP-F and dynamitin but not BUB1 with the kinetochore. Finally, our studies show that Zwint-1 is a new component of the mitotic check-point, as cells lacking Zwint-1 fail to arrest in mitosis when exposed to microtubule inhibitors, yielding interphase cells with multinuclei. As ZW10 and Zwint-1 are absent from yeast, we reasoned that metazoans evolved an elaborate spindle checkpoint machinery to ensure faithful chromosome segregation in mitosis.

Animals↗
PubMed2004

Amplification of IFN-alpha-induced STAT1 activation and inflammatory function by Syk and ITAM-containing adaptors.

A key function of interferons is priming multiple cell types for enhanced activation by cytokines and inflammatory factors, including tumor necrosis factor, bacterial lipopolysaccharide and interferons themselves. Here we show that interferon-alpha (IFN-alpha)-induced activation of the transcriptional activator STAT1 and inflammatory STAT1 target genes was enhanced in IFN-gamma-primed macrophages. Enhanced IFN-alpha signaling and proinflammatory function were dependent on the tyrosine kinase Syk and on adaptor proteins that activate Syk through immunoreceptor tyrosine activation motifs. Increased STAT1 expression contributed to enhanced IFN-alpha-induced STAT1 activation in primed macrophages. These results identify a mechanism by which crosstalk between cytokine and immune cell-specific immunoreceptor tyrosine activation motif-dependent signaling pathways regulates macrophage responses to IFN-alpha.

Adaptor Proteins, Vesicular Transport↗
PubMed2004

Signaling by STATs.

A variety of cytokines and growth factors use the Janus kinase (Jak)-STAT signaling pathway to transmit extracellular signals to the nucleus. STATs (signal transducers and activators of transcription) are latent cytoplasmic transcription factors. There are seven mammalian STATs and they have critical, nonredundant roles in mediating cellular transcriptional responses to cytokines. The physiological roles of STATs have been elucidated by analysis of mice rendered deficient in STAT genes. STAT activation is regulated and can be modulated in a positive or negative fashion; it can be reprogrammed to drive different cellular responses. Several auto-regulatory and signaling crosstalk mechanisms for regulating Jak-STAT signaling have been described. Understanding and manipulation of the function of STATs will help in the development of therapeutic strategies for diseases that are regulated by cytokines.

Animals↗
PubMed2003

Reprogramming of IL-10 activity and signaling by IFN-gamma.

One important mechanism of cross-regulation by opposing cytokines is inhibition of signal transduction, including inhibition of Janus kinase-STAT signaling by suppressors of cytokine signaling. We investigated whether IFN-gamma, a major activator of macrophages, inhibited the activity of IL-10, an important deactivator. Preactivation of macrophages with IFN-gamma inhibited two key anti-inflammatory functions of IL-10, the suppression of cytokine production and of MHC class II expression. Gene expression profiling showed that IFN-gamma broadly suppressed the ability of IL-10 to induce or repress gene expression. Although IFN-gamma induced expression of suppressor of cytokine signaling proteins, IL-10 signal transduction was not suppressed and IL-10 activation of Janus kinases and Stat3 was preserved. Instead, IFN-gamma switched the balance of IL-10 STAT activation from Stat3 to Stat1, with concomitant activation of inflammatory gene expression. IL-10 activation of Stat1 required the simultaneous presence of IFN-gamma. These results demonstrate that IFN-gamma operates a switch that rapidly regulates STAT activation by IL-10 and alters macrophage responses to IL-10. Dynamic regulation of the activation of different STATs by the same cytokine provides a mechanism by which cells can integrate and balance signals delivered by opposing cytokines, and extends our understanding of cross-regulation by opposing cytokines to include reprogramming of signaling and alteration of function.

Adjuvants, Immunologic↗
PubMed2003

Inhibition of IFN-gamma signaling by glucocorticoids.

Recent reports suggest that a novel mechanism of glucocorticoid (GC) immunosuppressive action is inhibition of signaling by IL-2 and IL-12, cytokines that use the Janus kinase-STAT signaling pathway. We investigated whether GCs could also block activation of Janus kinase-STAT signaling by IFN-gamma, a potent proinflammatory cytokine. Addition of dexamethasone to PBMC cultures resulted in a dramatic inhibition of IFN-gamma activation of STAT1. Several days of exposure to GCs were required for inhibition of IFN-gamma signaling to become apparent, and the underlying mechanism was down-regulation of STAT1 expression. GCs suppressed the expression of STAT1 mRNA, but did not affect STAT1 protein stability. STAT1 expression and IFN-gamma signaling were preferentially suppressed in macrophages. GCs did not act directly on macrophages, but worked indirectly by regulating macrophage-lymphocyte interactions that control STAT1 expression. GCs inhibited IFN-gamma-inducible gene expression, thus demonstrating the physiological significance of inhibition of signal transduction. Our results identify a novel level of regulation of IFN-gamma signaling, whereby GCs control the amplitude of IFN-gamma signaling by regulating STAT1 expression. These results suggest that inhibition of IFN-gamma signaling contributes to the immunosuppressive action of GCs.

Anti-Inflammatory Agents↗
PubMed2003

[Photodegradation of phthalic acid esters in water].

OBJECTIVE: To investigate the environmental degradation process of phthalic acid esters (PAEs). METHODS: The PAEs were detected by HPLC. We used the system of ultraviolet light, TiO2 and hydrogen peroxide to promote the photodegradation of PAEs in water. RESULTS: The photodegradation of PAEs was consistent with the first level kinetics. The maximal photodegradation of PAEs occurred at the 2.0 g/L of TiO2, pH 6.0, and 2.0% of H2O2. The importance of these environmental factors in promoting the photodegradation of PAEs were in the following orders: initial concentration of PAEs, radiation time, pH value, concentration of H2O2, and concentration of TiO2. CONCLUSION: The system of ultraviolet light, TiO2 and hydrogen peroxide was effective in promoting the photodegradation of PAEs.

Esters↗
PubMed2002

Sensitization of IFN-gamma Jak-STAT signaling during macrophage activation.

A general paradigm in signal transduction is ligand-induced feedback inhibition and the desensitization of signaling. We found that subthreshold concentrations of interferon-gamma (IFN-gamma), which did not activate macrophages, increased their sensitivity to subsequent IFN-gamma stimulation; this resulted in increased signal transducer and activator of transcription 1 (STAT1) activation and increased IFN-gamma#150;dependent gene activation. Sensitization of IFN-gamma signaling was mediated by the induction of STAT1 expression by low doses of IFN-gamma that did not effectively induce feedback inhibition. IFN-gamma signaling was sensitized in vivo after IFN-gamma injection, and STAT1 expression was increased after injection of lipopolysaccharide and in rheumatoid arthritis synovial cells. These results identify a mechanism that sensitizes macrophages to low concentrations of IFN-gamma and regulates IFN-gamma responses in acute and chronic inflammation.

Animals↗