Mingui Fu

University of Missouri - Kansas City, Kansas City, Missouri, United States

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Publications (50)253.74 Total impact

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    ABSTRACT: Macrophages within adipose tissue play a key role in mediating inflammatory responses in adipose tissue that are associated with obesity-related metabolic complications. In an effort to identify novel proteins secreted from adipocytes that may negatively regulate macrophage inflammation, we found that PAMM, a CXXC-type peroxiredoxin-like 2 domain-containing redox regulatory protein, is a novel secreted protein with potent anti-inflammatory properties. PAMM is secreted from mature human adipocytes but not preadipocytes. Overexpression of PAMM significantly attenuated lipopolysaccharide (LPS)-induced macrophage inflammation. Incubation of macrophages with adipocyte-conditional medium treated with anti-PAMM antibody significantly enhanced LPS-induced IL-12 expression in Raw264.7 cells. In addition, incubation of Raw264.7 cells with purified PAMM protein had a similar anti-inflammatory effect. Moreover, forced expression of PAMM in Raw264.7 cells resulted in decreased LPS-induced ERK1/2, p38 and JNK phosphorylation, suggesting that PAMM exerted the anti-inflammatory function probably by suppressing the MAPK signaling pathway. Mutations in the CXXC motif of PAMM that suppressed its anti-redox activity were still able to suppress production of inflammatory cytokines in LPS-stimulated macrophages, suggesting that PAMM's anti-inflammatory properties may be independent of its anti-oxidant properties. Finally, PAMM was highly expressed in both white and brown adipose tissues and further increased in obesity status. Our results suggest that adipocyte-derived PAMM may suppress macrophage activation by inhibiting MAPK signaling pathway.
    No preview · Article · Oct 2015 · Biochemical Journal
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    ABSTRACT: Coxsackievirus B3 (CVB3) is a causative agent of viral myocarditis, pancreatitis, and meningitis in humans. Although the susceptibility of CVB3-induced acute pancreatitis is age-dependent, the underlying mechanisms remain unclear. Here we identified the host factor Golgi matrix protein 130 (GM130) as a novel target of CVB3 during CVB3-induced acute pancreatitis. The viral protein VP1 interacted with GM130, disrupted GM130-GRASP65 complexes, and caused GM130 degradation, which may lead to disruption of the Golgi ribbon and development of acute pancreatitis in mice. Interestingly, the expression level of GM130 in mouse pancreas was age-dependent, which was nicely correlated with the age-associated susceptibility of CVB3-induced acute pancreatitis. Furthermore, interference RNA-mediated knockdown of GM130 significantly reduced CVB3 replication in HeLa cells. Taken together, the study identified GM130 as a novel target of CVB3, which may implicate in the pathogenesis of CVB3-induced acute pancreatitis.
    Preview · Article · Aug 2015 · Scientific Reports
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    ABSTRACT: It is recently demonstrated that MCPIP1 is a critical factor that controls inflammation and immune homeostasis, however, the relationship between MCPIP1 and other members in this protein family is largely unknown. Here we report that MCPIP1 interacts with MCPIP4 to form a protein complex but they act independently in regulation of IL-6 mRNA degradation. In an effort to identify MCPIP1-interacting proteins by co-immunoprecipitation (Co-IP) and Mass-spec analysis, MCPIP4 was identified as a MCPIP1-interacting protein, which was further confirmed by Co-IP and mammalian two-hybrid assay. Immunofluorescence staining showed that MCPIP4 was co-localized with MCPIP1 in GW-body, which is featured by GW182 and Argonaute 2. Further studies showed that MCPIP1 and MCPIP4 act independently in regulation of IL-6 mRNA degradation. These results suggest that MCPIP1 and MCPIP4 may additively contribute to control IL-6 production in vivo. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Full-text · Article · Jul 2015 · Journal of Biological Chemistry
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    ABSTRACT: DNA damage-induced NF-κB activation plays a critical role in regulating cellular response to genotoxic stress. However, the molecular mechanisms controlling the magnitude and duration of this genotoxic NF-κB signaling cascade are poorly understood. We recently demonstrated that genotoxic NF-κB activation is regulated by reversible ubiquitination of several essential mediators involved in this signaling pathway. Here we show that TRAF family member-associated NF-κB activator (TANK) negatively regulates NF-κB activation by DNA damage via inhibiting ubiquitination of TRAF6. Despite lack of a deubiquitination enzyme domain, TANK was shown to negatively regulate ubiquitination of TRAF proteins. We found TANK formed a complex with MCPIP1 (also known as ZC3H12A) and a deubiquitinase USP10, which was essential for USP10-dependent deubiquitination of TRAF6 and resolution of genotoxic NF-κB activation upon DNA damage. CRISPR/Cas9-mediated deletion of TANK in human cells significantly enhanced NF-κB activation by genotoxic treatments, resulting in enhanced cell survival and increased inflammatory cytokine production upon genotoxic drug treatment. Furthermore, we found that TANK-MCPIP1-USP10 complex also decreased TRAF6 ubiquitination in cells treated with IL-1β or LPS. In accordance, depletion of USP10 enhanced NF-κB activation induced by IL-1β or LPS. Collectively, our data demonstrate that TANK serves as an important negative regulator of NF-κB signaling cascades induced by genotoxic stress and IL-1R/TLR stimulation in a manner dependent on MCPIP1/USP10-mediated TRAF6 deubiquitination. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    No preview · Article · Apr 2015 · Journal of Biological Chemistry
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    ABSTRACT: There has been fast growing evidence showing that glycolysis plays a critical role in the activation of immune cells. Enhanced glycolysis leads to increased formation of intracellular lactate that is exported to the extracellular environment by monocarboxylate transporter 4 (MCT4). Although the biological activities of extracellular lactate have been well studied, it is less understood how the lactate export is regulated or if lactate export affects glycolysis during inflammatory activation. In this study, we found that MCT4 is upregulated by TLR2 and TLR4, but not TLR3 agonists in a variety of macrophages. The increased expression of MCT4 was mediated by MYD88 in a NF-κB dependent manner. Furthermore, we found that MCT4 is required for macrophage activation upon TLR2 and TLR4 stimulations, as evidenced by attenuated expression of pro-inflammatory mediators in macrophages with MCT4 knockdown. Mechanistically, we found that MCT4 knockdown leads to enhanced intracellular accumulation of lactate and decreased glycolysis in LPS treated macrophages. We found that LPS induced expression of key glycolytic enzymes hexokinase 2 (HK2) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) is diminished in macrophages with MCT4 knockdown. Our data suggest that MCT4 upregulation represents a positive feedback mechanism in macrophages to maintain a high glycolytic rate that is essential to a fully activated inflammatory response. Copyright © 2014, The American Society for Biochemistry and Molecular Biology.
    No preview · Article · Nov 2014 · Journal of Biological Chemistry
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    ABSTRACT: Although microRNAs were shown to participate in innate immune responses, it is not completely understood how they regulate negative immunomodulatory events. IL-10 is an important anti-inflammatory mediator that prevents excessive inflammation and associated immunological pathologies. Although the regulation of IL-10 expression has been well studied at both the transcriptional and translational levels, it is less clear how microRNAs control IL-10 expression during inflammation. In this study, we found that miR-27a is downregulated in macrophages following stimulation through TLR2 and TLR4, but not TLR3. Upregulation of miR-27a enhanced the expression of proinflammatory cytokines in TLR2/4-activated macrophages. Conversely, knockdown of miR-27a diminished cytokine expression. Mechanistically, we found that miR-27a negatively regulates IL-10 expression; upregulation of miR-27a decreases, whereas downregulation of miR-27a increases, IL-10 expression in activated macrophages. Likely due to the decreased expression of IL-10, upregulation of miR-27a diminished IL-10-dependent STAT3 phosphorylation in TLR4-activated macrophages. Consistent with IL-10 being a potential mediator for the role of miR-27a in the immune response, blocking IL-10 abolished the enhancing effect of miR-27a on TLR4-activated inflammation. In conclusion, our study identified miR-27a downregulation as a negative-regulatory mechanism that prevents overly exuberant TLR2- and TLR4-driven inflammatory responses.
    No preview · Article · May 2014 · The Journal of Immunology
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    ABSTRACT: microRNA-155 (miR155) plays a critical role in immunity and macrophage inflammation. We aim to investigate the role of miR155 in atherogenesis. Quantitative real-time polymerase chain reaction showed that miR155 was expressed in mouse and human atherosclerotic lesions. miR155 expression in macrophages was correlated positively with proinflammatory cytokine expression. Lentivirus-mediated overexpression of miR155 in macrophages enhanced their inflammatory response to lipopolysaccharide through targeting SOCS-1 and impaired cholesterol efflux from acetylated low-density lipoprotein-loaded macrophages, whereas deficiency of miR155 blunted macrophage inflammatory responses and enhanced cholesterol efflux possibly via enhancing lipid loading-induced macrophage autophagy. We next examined the atherogenesis in apolipoprotein E-deficient (apoE(-/-)) and miR155(-/-)/apoE(-/-) (double knockout) mice fed a Western diet. Compared with apoE(-/-) mice, the double knockout mice developed less atherosclerosis lesion in aortic root, with reduced neutral lipid content and macrophages. Flow cytometric analysis showed that there were increased number of regulatory T cells and reduced numbers of Th17 cells and CD11b+/Ly6C(high) cells in the spleen of double knockout mice. Peritoneal macrophages from the double knockout mice had significantly reduced proinflammatory cytokine expression and secretion both in the absence and presence of lipopolysaccharide stimulation. To determine whether miR155 in leukocytes contributes to atherosclerosis, we performed bone marrow transplantation study. Deficiency of miR155 in bone marrow-derived cells suppressed atherogenesis in apoE(-/-) mice, demonstrating that hematopoietic cell-derived miR155 plays a critical role. miR155 deficiency attenuates atherogenesis in apoE(-/-) mice by reducing inflammatory responses of macrophages, enhancing macrophage cholesterol efflux and resulting in an antiatherogenic leukocyte profile. Targeting miR155 may be a promising strategy to halt atherogenesis.
    Full-text · Article · Feb 2014 · Arteriosclerosis Thrombosis and Vascular Biology
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    ABSTRACT: Autoimmune gastritis is an organ-specific autoimmune disease of the stomach associated with pernicious anemia. The previous work from us and other groups identified MCPIP1 as an essential factor controlling inflammation and immune homeostasis. MCPIP1(-/-) developed severe anemia. However, the mechanisms underlying this phenotype remain unclear. In the present study, we found that MCPIP1 deficiency in mice resulted in severe anemia related to autoimmune mechanisms. Although MCPIP1 deficiency did not affect erythropoiesis per se, the erythropoiesis in MCPIP1(-/-) bone marrow erythroblasts was significantly attenuated due to iron and vitamin B12 (VB12) deficiency, which was mainly resulted from autoimmunity-associated gastritis and parietal cell loss. Consistently, exogenous supplement of iron and VB12 greatly improved the anemia phenotype of MCPIP1(-/-) mice. Finally, we have evidence suggesting that autoimmune hemolysis may also contribute to anemia phenotype of MCPIP1(-/-) mice. Taken together, our study suggests that MCPIP1 deficiency in mice leads to the development of autoimmune gastritis and pernicious anemia. Thus, MCPIP1(-/-) mice may be a good mouse model for investigating the pathogenesis of pernicious anemia and testing the efficacy of some potential drugs for treatment of this disease.
    Full-text · Article · Dec 2013 · PLoS ONE
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    ABSTRACT: DNA damage-induced activation of the transcription factor NF-κB plays an important role in the cellular response to genotoxic stress. However, uncontrolled NF-κB activation upon DNA damage may lead to deleterious consequences. Although the mechanisms mediating genotoxic NF-κB activation have been elucidated, how this signalling is terminated remains poorly understood. Here, we show that the CCCH-type zinc finger-containing protein MCPIP1 (monocyte chemotactic protein-1-induced protein-1; also known as ZC3H12A) is induced upon genotoxic treatment in an NF-κB-dependent manner. MCPIP1 upregulation reduces NEMO linear ubiquitylation, resulting in decreased activation of IKK and NF-κB. NEMO ubiquitylation is decreased through the deubiquitinase USP10, which interacts with NEMO via MCPIP1 upon genotoxic stress. USP10 association with NEMO leads to removal of NEMO-attached linear polyubiquitin chains and subsequent inhibition of the genotoxic NF-κB signalling cascade. Consistently, USP10 is required for MCPIP1-mediated inhibition of genotoxic NF-κB activation and promotion of apoptosis. Thus, by mediating USP10-dependent deubiquitination of NEMO, MCPIP1 induction serves as a negative feedback mechanism for attenuating genotoxic NF-κB activation.
    Full-text · Article · Nov 2013 · The EMBO Journal
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    ABSTRACT: MCPIP1 is a newly identified protein that profoundly impacts immunity and inflammation. We aim to test if MCPIP1 deficiency in hematopoietic cells results in systemic inflammation and accelerates atherogenesis in mice. After lethally irradiated, LDLR(-/-) mice were transplanted with bone marrow cells from either wild-type or MCPIP1(-/-) mice. These chimeric mice were fed a western-type diet for 7 weeks. We found that bone marrow MCPIP1(-/-) mice displayed a phenotype similar to that of whole body MCPIP1(-/-) mice, with severe systemic and multi-organ inflammation. However, MCPIP1(-/-) bone marrow recipients developed >10-fold less atherosclerotic lesions in the proximal aorta than WT bone marrow recipients, and essentially no lesions in en face aorta. The diminishment in atherosclerosis in bone marrow MCPIP1(-/-) mice may be partially attributed to the slight decrease in their plasma lipids. Flow cytometric analysis of splenocytes showed that bone marrow MCPIP1(-/-) mice contained reduced numbers of T cells and B cells, but increased numbers of regulatory T cells, Th17 cells, CD11b+/Gr1+ cells and CD11b+/Ly6C(low) cells. This overall anti-atherogenic leukocyte profile may also contribute to the reduced atherogenesis. We also examined the cholesterol efflux capability of MCPIP1 deficient macrophages, and found that MCPIP1deficiency increased cholesterol efflux to apoAI and HDL, due to increased protein levels of ABCA1 and ABCG1. Hematopoietic deficiency of MCPIP1 resulted in severe systemic and multi-organ inflammation but paradoxically diminished atherogenesis in mice. The reduced atheroegensis may be explained by the decreased plasma cholesterol levels, the anti-atherogenic leukocyte profile, as well as enhanced cholesterol efflux capability. This study suggests that, while atherosclerosis is a chronic inflammatory disease, the mechanisms underlying atherogenesis-associated inflammation in arterial wall versus the inflammation in solid organs may be substantially different.
    Full-text · Article · Nov 2013 · PLoS ONE
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    ABSTRACT: HIV-1 primarily infects activated CD4+ T cells and macrophages. Quiescent CD4+ T cells, however, possess cellular factors that limit HIV-1 infection at different postentry steps of the viral life cycle. Here, we show that the previously reported immune regulator monocyte chemotactic protein-induced protein 1 (MCPIP1) restricts HIV-1 production in CD4+ T cells. While the ectopic expression of MCPIP1 in cell lines abolished the production of HIV-1, silencing of MCPIP1 enhanced HIV-1 production. Subsequent analysis indicated that MCPIP1 imposes its restriction by decreasing the steady levels of viral mRNA species through its RNase domain. Remarkably, common T-cell stimuli induced the rapid degradation of MCPIP1 in both T-cell lines and quiescent human CD4+ T cells. Lastly, blocking the proteosomal degradation of MCPIP1 by MG132 abrogated HIV-1 production in phorbol 12-myristate 13-acetate/ionomycin-stimulated human CD4+ T cells isolated from healthy donors. Overall, MCPIP1 poses a potent barrier against HIV-1 infection at a posttranscriptional stage. Although the observed HIV restriction conferred by MCPIP1 does not seem to be overcome by any viral protein, it is removed during cellular stimulation. These findings provide insights into the mechanisms of cellular activation-mediated HIV-1 production in CD4+ T cells.
    Full-text · Article · Nov 2013 · Proceedings of the National Academy of Sciences
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    ABSTRACT: Tristetraprolin (TTP), an mRNA-binding protein, plays a significant role in regulating the expression of adenylate-uridylate-rich elements containing mRNAs. Mice deficient of TTP (TTP(-/-)) develop a systemic autoimmune inflammatory syndrome characterized by cachexia, conjunctivitis, and dermatitis. IL-12 plays a crucial role in immune defense against infectious and malignant diseases. In this study, we found increased production of IL-12 during endotoxic shock and enhanced Th1 cells in TTP knockout mice. The levels of IL-12 p70 and p40 protein as well as p40 and p35 mRNA were also increased in activated macrophages deficient of TTP. In line with these findings, overexpression of TTP suppressed IL-12 p35 and p40 expression at the mRNA and promoter level, whereas it surprisingly had little effects on their mRNA stability. Our data showed that the inhibitory effects of TTP on p35 gene transcription were completely rescued by overexpression of NF-кB p65 and c-Rel but not by the p50 in activated macrophages. Our data further indicated that TTP acquired its inhibition on IL-12 expression through blocking nuclear translocation of NF-кB p65 and c-Rel while enhancing p50 upon stimulation. In summary, our study reveals a novel pathway through which TTP suppresses IL-12 production in macrophages, resulting in suppression of Th1 cell differentiation. This study may provide us with therapeutic targets for treatment of inflammatory and autoimmune disorders.
    No preview · Article · Aug 2013 · The Journal of Immunology
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    ABSTRACT: Tumor cell-derived molecules such as cytokines and lipid mediators play a critical role in inducing chronic inflammation in the tumor microenvironment. We found that Th17 cells were increased in the peripheral blood, spleen, and tumor tissues of mammary gland tumor-bearing mice. The Th17 cell survival factor, IL-23, was also overexpressed in tumor tissues isolated from mice and human breast cancer patients. Soluble molecules secreted from breast tumor cells, but not normal breast epithelial cells, induced IL-23 protein secretion in dendritic cells via induction of p19 mRNA expression. Our data further indicate that tumor-secreted PGE2 through EP2 and EP4 receptors enhanced IL-23 p19 gene transcription through binding to the cAMP-response element in the p19 promoter. Blocking PGE2 synthesis by NS398, a COX2 inhibitor, abrogated the enhancement of p19 expression both in vitro and in vivo. Furthermore, blocking protein kinase A (PKA) by H89 completely abrogated the inductive effects of tumor-conditioned medium and PGE2 on p19 transcription, whereas the cAMP active analog, Forskolin, mimics the PGE2 effect. Taken together, our results indicate that tumor-secreted PGE2 induces IL-23, but not IL-12, production in the tumor microenvironment, leading to Th17 cell expansion. This inductive effect of PGE2 on IL-23 p19 transcription is mediated through cAMP/PKA signaling transduction pathway.
    Full-text · Article · May 2013 · The Journal of Immunology
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    ABSTRACT: Previous studies using MCP-induced protein 1 (MCPIP1)/Zc3h12a-deficient mice suggest that MCPIP1 is an important regulator of inflammation and immune homeostasis. However, the characterization of the immunological phenotype of MCPIP1-deficient mice has not been detailed. In this study, we performed evaluation through histological, flow cytometric, enzyme-linked immunosorbent assay and real-time PCR analysis and found that targeted disruption of MCPIP1 gene leads to fatal, highly aggressive and widespread immune-related lesions. In addition to previously observed growth retardation, splenomegaly, lymphoadenopathy, severe anemia and premature death, MCPIP1-deficient mice showed disorganization of lymphoid organs, including spleen, lymph nodes and thymus, and massive infiltration of lymphocytes, macrophages and neutrophils into many other non-lymphoid organs, primarily in lungs and liver. Flow cytometric analysis found significant increase in activated and differentiated T cells in peripheral blood and spleen of MCPIP1-deficient mice. Moreover, heightened production of inflammatory cytokines from activated macrophages and T cells were observed in MCPIP1-deficient mice. Interestingly, treatment of MCPIP1-deficient mice with antibiotics resulted in significant improvement of life span and a decrease in inflammatory syndrome. Taken together, these results suggest a prominent role for MCPIP1 in the control of inflammation and immune homeostasis.Immunology and Cell Biology advance online publication, 9 April 2013; doi:10.1038/icb.2013.11.
    Full-text · Article · Apr 2013 · Immunology and Cell Biology
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    ABSTRACT: The molecular mechanism to regulate energy balance is not completely understood. Here we observed that Egr-1 expression in white adipose tissue (WAT) was highly correlated with dietary-induced obesity and insulin resistance both in mice and humans. Egr-1 null mice were protected from diet-induced obesity and obesity-associated pathologies such as fatty liver, insulin resistance, hyperlipidemia and hyperinsulinemia. This phenotype can be largely explained by the increase of energy expenditure in Egr-1 null mice. Characterization of these mice revealed that the expression of FOXC2 and its target genes were significantly elevated in white adipose tissues, leading to WAT energy expenditure instead of energy storage. Altogether, these studies suggest an important role for Egr-1, which, by repressing FOXC2 expression, promotes energy storage in WAT and favored the development of obesity under high energy intake.
    Full-text · Article · Mar 2013 · Scientific Reports
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    ABSTRACT: Septic shock is one of leading causes of morbidity and mortality in hospital patients. However, genetic factors predisposing to septic shock are not fully understood. Our previous work showed that MCP-induced protein 1 (MCPIP1) was induced by lipopolysaccharides (LPSs), which then negatively regulates LPS-induced inflammatory signaling in vitro. Here we report that although MCPIP1 was induced by various toll-like receptor (TLR) ligands in macrophages, MCPIP1-deficient mice are extremely susceptible to TLR4 ligand (LPS)-induced septic shock and death, but not to the TLR2, 3, 5 and 9 ligands-induced septic shock. Consistently, LPS induced tumor necrosis factor α (TNFα) production in MCPIP1-deficient mice was 20-fold greater than that in their wild-type littermates. Further analysis revealed that MCPIP1-deficient mice developed severe acute lung injury after LPS injection and JNK signaling was highly activated in MCPIP1-deficient lungs after LPS stimulation. Finally, macrophage-specific MCPIP1 transgenic mice were partially protected from LPS-induced septic shock, suggesting that inflammatory cytokines from sources other than macrophages may significantly contribute to the pathogenesis of LPS-induced septic shock. Taken together, these results suggest that MCPIP1 selectively suppresses TLR4 signaling pathway and protects mice from LPS-induced septic shock.
    Full-text · Article · Feb 2013 · Cellular Signalling
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    ABSTRACT: Endothelial activation characterized by the expression of multiple chemokines and adhesive molecules is a critical initial step of vascular inflammation which results in recruitment of leukocytes into sub-endothelial layer of vascular wall and triggers vascular inflammatory diseases such as atherosclerosis. Although inhibiting the endothelial inflammation has already been well recognized as a therapeutic strategy in vascular inflammatory diseases, the therapeutic targets are still elusive. In the present study we found that Zc3h12c, a recently discovered CCCH-zinc finger containing protein, significantly inhibited endothelial cell inflammatory response in vitro. Overexpression of Zc3h12c significantly attenuated tumor necrosis factor a (TNFa) induced expression of chemokines and adhesive molecules, and thus reduced monocyte adherence to human umbilical vein endothelial cells (HUVECs). Conversely, siRNA-mediated knocking down of Zc3h12c increased TNFα-induced expression of chemokines and adhesive molecules in HUVECs. Furthermore, forced expression of Zc3h12c decreased TNFα-induced IKKa/b and IkBa phosphorylation and p65 nuclear translocation, suggesting that Zc3h12c exerted the anti-inflammatory function probably by suppressing nuclear factor-kB (NF-kB) pathway. Thus, Zc3h12c is an endogenous inhibitor of TNFα-induced inflammatory signaling in HUVECs and might be a therapeutic target in vascular inflammatory diseases.
    Full-text · Article · Jan 2013 · Biochemical Journal
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    ABSTRACT: MicroRNAs (miRNA) control numerous physiological and pathological processes. Typically, the primary miRNA (pri-miRNA) transcripts are processed by nuclear Drosha complex into ∼70-nucleotide stem-loop precursor miRNAs (pre-miRNA), which are further cleaved by cytoplasmic Dicer complex into ∼21-nucleotide mature miRNAs. However, it is unclear how nascent pre-miRNAs are protected from ribonucleases, such as MCPIP1, that degrade pre-miRNAs to abort miRNA production. Here, we identify Sjögren syndrome antigen B (SSB)/La as a pre-miRNA-binding protein that regulates miRNA processing in vitro. All three RNA-binding motifs (LAM, RRM1, and RRM2) of La/SSB are required for efficient pre-miRNA binding. Intriguingly, La/SSB recognizes the characteristic stem-loop structure of pre-miRNAs, of which the majority lack a 3′ UUU terminus. Moreover, La/SSB associates with endogenous pri-/pre-miRNAs and promotes miRNA biogenesis by stabilizing pre-miRNAs from nuclease (e.g. MCPIP1)-mediated decay in mammalian cells. Accordingly, we observed positive correlations between the expression status of La/SSB and Dicer in human cancer transcriptome and prognosis. These studies identify an important function of La/SSB as a global regulator of miRNA expression, and implicate stem-loop recognition as a major mechanism that mediates association between La/SSB and diverse RNA molecules.
    No preview · Article · Nov 2012 · Journal of Biological Chemistry
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    ABSTRACT: Clearance of apoptotic cells (efferocytosis) is critical to the homeostasis of the immune system by restraining inflammation and autoimmune response to intracellular Ags released from dying cells. TLRs-mediated innate immunity plays an important role in pathogen clearance and in regulation of the adaptive immune response. However, the regulation of efferocytosis by activation of TLRs has not been well characterized. In this study, we found that activation of TLR3 or TLR9, but not of TLR2, enhances engulfment of apoptotic cells by macrophages. We found that the activation of TLR3 upregulates the expression of triggering receptor expressed on myeloid cells (TREM)-like protein 2 (TLT2), a member of the TREM receptor family, on the surface of macrophages. Blocking TLT2 on the macrophage surface by either specific anti-TLT2 Ab or soluble TLT2 extracellular domain attenuated the enhanced ability of macrophages with TLR3 activation to engulf apoptotic cells. To the contrary, overexpression of TLT2 increased the phagocytosis of apoptotic cells. We found that TLT2 specifically binds to phosphatidylserine, a major "eat me" signal that is exposed on the surface of apoptotic cells. Furthermore, we found that TLT2 mediates phagocytosis of apoptotic cells in vivo. Thus, our studies identified TLT2 as an engulfment receptor for apoptotic cells. Our data also suggest a novel mechanism by which TREM receptors regulate inflammation and autoimmune response.
    Preview · Article · May 2012 · The Journal of Immunology
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    ABSTRACT: Liver X receptors (LXRα and LXRβ) are important regulators of cholesterol and lipid metabolism, and their activation has been shown to inhibit cardiovascular disease and reduce atherosclerosis in animal models. Small molecule agonists of LXR activity are therefore of great therapeutic interest. However, the finding that such agonists also promote hepatic lipogenesis has led to the idea that hepatic LXR activity is undesirable from a therapeutic perspective. To investigate whether this might be true, we performed gene targeting to selectively delete LXRα in hepatocytes. Liver-specific deletion of LXRα in mice substantially decreased reverse cholesterol transport, cholesterol catabolism, and cholesterol excretion, revealing the essential importance of hepatic LXRα for whole body cholesterol homeostasis. Additionally, in a pro-atherogenic background, liver-specific deletion of LXRα increased atherosclerosis, uncovering an important function for hepatic LXR activity in limiting cardiovascular disease. Nevertheless, synthetic LXR agonists still elicited anti-atherogenic activity in the absence of hepatic LXRα, indicating that the ability of agonists to reduce cardiovascular disease did not require an increase in cholesterol excretion. Furthermore, when non-atherogenic mice were treated with synthetic LXR agonists, liver-specific deletion of LXRα eliminated the detrimental effect of increased plasma triglycerides, while the beneficial effect of increased plasma HDL was unaltered. In sum, these observations suggest that therapeutic strategies that bypass the liver or limit the activation of hepatic LXRs should still be beneficial for the treatment of cardiovascular disease.
    Full-text · Article · Apr 2012 · The Journal of clinical investigation

Publication Stats

2k Citations
253.74 Total Impact Points

Institutions

  • 2011-2015
    • University of Missouri - Kansas City
      • Department of Basic Med Sciences
      Kansas City, Missouri, United States
  • 2007-2013
    • University of Texas Southwestern Medical Center
      • Department of Pharmacology
      Dallas, Texas, United States
  • 2007-2010
    • University of Central Florida
      • • Burnett School of Biomedical Sciences
      • • Graduate Program in Molecular Biology and Microbiology
      • • College of Medicine
      Orlando, Florida, United States
  • 2006
    • University of Texas at Dallas
      Richardson, Texas, United States
  • 2002-2005
    • Morehouse School of Medicine
      Atlanta, Georgia, United States