Ultrasensitive vibrational resonance induced by small disturbances.

We have found two kinds of ultrasensitive vibrational resonance in coupled nonlinear systems. It is particularly worth pointing out that this ultrasensitive vibrational resonance is transient behavior caused by transient chaos. Considering a long-term response, the system will transform from transient chaos to a periodic response. The pattern of vibrational resonance will also transform from ultrasensitive vibrational resonance to conventional vibrational resonance. This article focuses on the transient ultrasensitive vibrational resonance phenomenon. It is induced by a small disturbance of the high-frequency excitation and the initial simulation conditions, respectively. The damping coefficient and the coupling strength are the key factors to induce the ultrasensitive vibrational resonance. By increasing these two parameters, the vibrational resonance pattern can be transformed from ultrasensitive vibrational resonance to conventional vibrational resonance. The reason for different vibrational resonance patterns to occur lies in the state of the system response. The response usually presents transient chaotic behavior when the ultrasensitive vibrational resonance appears and the plot of the response amplitude vs the controlled parameters shows a highly fractalized pattern. When the response is periodic or doubly periodic, it usually corresponds to the conventional vibrational resonance. The ultrasensitive vibrational resonance not only occurs at the excitation frequency, but it also occurs at some more nonlinear frequency components. The ultrasensitive vibrational resonance as transient behavior and the transformation of vibrational resonance patterns are new phenomena in coupled nonlinear systems.

Separable roles for RanGTP in nuclear and ciliary trafficking of a kinesin-2 subunit.

Kinesin is part of the microtubule-binding motor protein superfamily, which serves important roles in cell division and intraorganellar transport. The heterotrimeric kinesin-2, consisting of the heterodimeric motor subunits, kinesin family member 3A/3B (KIF3A/3B), and kinesin-associated protein 3 (KAP3), is highly conserved across species from the unicellular eukaryote Chlamydomonas to humans. It plays diverse roles in cargo transport including anterograde (base to tip) trafficking in cilia. However, the molecular determinants mediating trafficking of heterotrimeric kinesin-2 itself are poorly understood. It has been previously suggested that ciliary transport is analogous to nuclear transport mechanisms. Using Chlamydomonas and human telomerase reverse transcriptase-retinal pigment epithelial cell line, we show that RanGTP, a small GTPase that dictates nuclear transport, regulates ciliary trafficking of KAP3, a key component for functional kinesin-2. We found that the armadillo-repeat region 6 to 9 (ARM6-9) of KAP3, required for its nuclear translocation, is also necessary and sufficient for its targeting to the ciliary base. Given that KAP3 is essential for cilium formation and there are the emerging roles for RanGTP/importin ß in ciliary protein targeting, we further investigated the effect of RanGTP in cilium formation and maintenance. We found that precise control of RanGTP levels, revealed by different Ran mutants, is crucial for cilium formation and maintenance. Most importantly, we were able to provide orthogonal support in an algal model system that segregates RanGTP regulation of ciliary protein trafficking from its nuclear roles. Our work provides important support for the model that nuclear import mechanisms have been co-opted for independent roles in ciliary import.

Inhibition of Endothelial PHD2 Suppresses Post-Ischemic Kidney Inflammation through Hypoxia-Inducible Factor-1.

BACKGROUND: Prolyl-4-hydroxylase domain-containing proteins 1-3 (PHD1 to PHD3) regulate the activity of the hypoxia-inducible factors (HIFs) HIF-1 and HIF-2, transcription factors that are key regulators of hypoxic vascular responses. We previously reported that deficiency of endothelial HIF-2 exacerbated renal ischemia-reperfusion injury, whereas inactivation of endothelial PHD2, the main oxygen sensor, provided renoprotection. Nevertheless, the molecular mechanisms by which endothelial PHD2 dictates AKI outcomes remain undefined. METHODS: To investigate the function of the endothelial PHD2/HIF axis in ischemic AKI, we examined the effects of endothelial-specific ablation of PHD2 in a mouse model of renal ischemia-reperfusion injury. We also interrogated the contribution of each HIF isoform by concurrent endothelial deletion of both PHD2 and HIF-1 or both PHD2 and HIF-2. RESULTS: Endothelial deletion of Phd2 preserved kidney function and limited transition to CKD. Mechanistically, we found that endothelial Phd2 ablation protected against renal ischemia-reperfusion injury by suppressing the expression of proinflammatory genes and recruitment of inflammatory cells in a manner that was dependent on HIF-1 but not HIF-2. Persistence of renoprotective responses after acute inducible endothelial-specific loss of Phd2 in adult mice ruled out a requirement for PHD2 signaling in hematopoietic cells. Although Phd2 inhibition was not sufficient to induce detectable HIF activity in the kidney endothelium, in vitro experiments implicated a humoral factor in the anti-inflammatory effects generated by endothelial PHD2/HIF-1 signaling. CONCLUSIONS: Our findings suggest that activation of endothelial HIF-1 signaling through PHD2 inhibition may offer a novel therapeutic approach against ischemic AKI.

USP10 inhibits genotoxic NF-κB activation by MCPIP1-facilitated deubiquitination of NEMO.

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.

Monocyte Chemotactic Protein-induced Protein 1 and 4 Form a Complex but Act Independently in Regulation of Interleukin-6 mRNA Degradation.

It was recently demonstrated that MCPIP1 is a critical factor that controls inflammation and immune homeostasis; however, the relationship between MCPIP1 and other members of this protein family is largely unknown. Here, we report that MCPIP1 interacts with MCPIP4 to form a protein complex, but acts independently in the 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 the GW-body, which features 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.

Adipocyte-derived PAMM suppresses macrophage inflammation by inhibiting MAPK signalling.

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 peroxiredoxin (PRX)-like 2 activated in M-CSF stimulated monocytes (PAMM), a CXXC-type PRX-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 interleukin-12 (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 c-Jun N-terminal kinase (JNK) phosphorylation, suggesting that PAMM exerted the anti-inflammatory function probably by suppressing the mitogen-activated protein kinase (MAPK) signalling 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 antioxidant properties. Finally, PAMM was highly expressed in both white (WAT) and brown adipose tissues (BAT) and further increased in obesity status. Our results suggest that adipocyte-derived PAMM may suppress macrophage activation by inhibiting MAPK signalling pathway.

Identification of a high-efficiency baculovirus DNA replication origin that functions in insect and mammalian cells.

UNLABELLED: The p143 gene from Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) has been found to increase the expression of luciferase, which is driven by the polyhedrin gene promoter, in a plasmid with virus coinfection. Further study indicated that this is due to the presence of a replication origin (ori) in the coding region of this gene. Transient DNA replication assays showed that a specific fragment of the p143 coding sequence, p143-3, underwent virus-dependent DNA replication in Spodoptera frugiperda IPLB-Sf-21 (Sf-21) cells. Deletion analysis of the p143-3 fragment showed that subfragment p143-3.2a contained the essential sequence of this putative ori. Sequence analysis of this region revealed a unique distribution of imperfect palindromes with high AT contents. No sequence homology or similarity between p143-3.2a and any other known ori was detected, suggesting that it is a novel baculovirus ori. Further study showed that the p143-3.2a ori can replicate more efficiently in infected Sf-21 cells than baculovirus homologous regions (hrs), the major baculovirus ori, or non-hr oris during virus replication. Previously, hr on its own was unable to replicate in mammalian cells, and for mammalian viral oris, viral proteins are generally required for their proper replication in host cells. However, the p143-3.2a ori was, surprisingly, found to function as an efficient ori in mammalian cells without the need for any viral proteins. We conclude that p143 contains a unique sequence that can function as an ori to enhance gene expression in not only insect cells but also mammalian cells. IMPORTANCE: Baculovirus DNA replication relies on both hr and non-hr oris; however, so far very little is known about the latter oris. Here we have identified a new non-hr ori, the p143 ori, which resides in the coding region of p143. By developing a novel DNA replication-enhanced reporter system, we have identified and located the core region required for the p143 ori. This ori contains a large number of imperfect inverted repeats and is the most active ori in the viral genome during virus infection in insect cells. We also found that it is a unique ori that can replicate in mammalian cells without the assistance of baculovirus gene products. The identification of this ori should contribute to a better understanding of baculovirus DNA replication. Also, this ori is very useful in assisting with gene expression in mammalian cells.

A second CRM1-dependent nuclear export signal in the influenza A virus NS2 protein contributes to the nuclear export of viral ribonucleoproteins.

Influenza A virus NS2 protein, also called nuclear export protein (NEP), is crucial for the nuclear export of viral ribonucleoproteins. However, the molecular mechanisms of NEP mediation in this process remain incompletely understood. A leucine-rich nuclear export signal (NES2) in NEP, located at the predicted N2 helix of the N-terminal domain, was identified in the present study. NES2 was demonstrated to be a transferable NES, with its nuclear export activity depending on the nuclear export receptor chromosome region maintenance 1 (CRM1)-mediated pathway. The interaction between NEP and CRM1 is coordinately regulated by both the previously reported NES (NES1) and now the new NES2. Deletion of the NES1 enhances the interaction between NEP and CRM1, and deletion of the NES1 and NES2 motifs completely abolishes this interaction. Moreover, NES2 interacts with CRM1 in the mammalian two-hybrid system. Mutant viruses containing NES2 alterations generated by reversed genetics exhibit reduced viral growth and delay in the nuclear export of viral ribonucleoproteins (vRNPs). The NES2 motif is highly conserved in the influenza A and B viruses. The results demonstrate that leucine-rich NES2 is involved in the nuclear export of vRNPs and contributes to the understanding of nucleocytoplasmic transport of influenza virus vRNPs.

Zc3h12c inhibits vascular inflammation by repressing NF-κB activation and pro-inflammatory gene expression in endothelial cells.

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 leucocytes into the sub-endothelial layer of the vascular wall and triggers vascular inflammatory diseases such as atherosclerosis. Although inhibiting 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 (zinc finger CCCH-type-containing 12C), a recently discovered CCCH zinc finger-containing protein, significantly inhibited the endothelial cell inflammatory response in vitro. Overexpression of Zc3h12c significantly attenuated TNFα (tumour necrosis factor α)-induced expression of chemokines and adhesive molecules, and thus reduced monocyte adherence to HUVECs (human umbilical vein endothelial cells). Conversely, siRNA (small interfering RNA)-mediated knockdown of Zc3h12c increased the TNFα-induced expression of chemokines and adhesive molecules in HUVECs. Furthermore, forced expression of Zc3h12c decreased TNFα-induced IKKα/ß [IκB (inhibitor of nuclear factor κB) kinase α/ß], IκBα phosphorylation and p65 nuclear translocation, suggesting that Zc3h12c exerted its anti-inflammatory function probably by suppressing the NF-κB (nuclear factor κB) pathway. Thus Zc3h12c is an endogenous inhibitor of TNFα-induced inflammatory signalling in HUVECs and might be a therapeutic target in vascular inflammatory diseases.

Postoperative hemorrhage in an elderly patient with a glioblastoma multiform and a calcified chronic subdural hematoma.

BACKGROUND: Cases with brain tumor and subdural hematoma are rare; surgical management of the elderly patients with a glioblastoma multiform (GBM) and a chronic subdural hematoma (CSDH) can be intractable. CASE DESCRIPTION: We report a 77-year-old patient, who had a left front lobe GBM and a giant, calcified, left frontoparietaloccipitotemporal CSDH. The patient recovered well from anesthesia after removal of the GBM and CSDH. However, the patient developed severe hemiplegia and aphasia because of the in-situ hemorrhage 1 day later. Laboratory tests indicated disseminated intravascular coagulation (DIC) leading to the postoperative hemorrhage. The patient was left with hemiparesis and alalia after the in-situ hematoma evacuation. CONCLUSIONS: We presume elderly patients have a higher incidence of postoperative hemorrhage in residual intracranial cavity owing to higher possibility to get DIC. A less aggressive surgical management could be a more appropriate choice.

Impact of typhoon events on microplastic distribution in offshore sediments in Leizhou Peninsula of the South China Sea.

Microplastic is an emerging pollutant and a technical fossil in Anthropocene sediments. Typhoon frequency and intensity have increased due to climate change, which has a major effect on the distribution patterns of microplastics. It is still unknown, though, how the topography of the peninsula affects the reconstruction of the distribution of microplastic in typhoons. Due to frequent typhoons, the Leizhou Peninsula (LZP) in the north part of the South China Sea is an ideal place to study the impact of topographic variations on microplastic distribution during typhoon events. This study investigated microplastics ranging in size from 50 µm to 5 mm in sediment. Microscopic inspection and µ-FTIR tests were used to identify microplastic characteristics from offshore surface sediments before and after typhoons. The average microplastic abundance in offshore sediments decreased from 18 ± 17 items/kg to 15 ± 15 items/kg after typhoons. Results show that typhoons only increase the microplastic abundance in topographically protected areas along the northeast coast of LZP, with no significant difference observed in other regions. The influence of typhoon on the morphological characteristics of microplastics in sediments is more pronounced and widespread, as evidenced by a shift in the predominant shape of microplastics from fibers to fragments and a decrease in size accompanied by an increased abundance within the 100 µm-1 mm fraction. The color of microplastics remained similar before and after typhoons, and the polymer composition of microplastics became more uniform. The alteration of microplastic morphology may be attributed to the enhancement of wave intensity induced by typhoons. This study enhances the comprehension of typhoon-induced impacts on pollutant redistribution, specifically microplastics, thereby providing essential empirical evidence and theoretical foundations for pollution regulation.

Targeted disruption of MCPIP1/Zc3h12a results in fatal inflammatory disease.

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.

Promotion of wound healing using adipose-derived stem cells in radiation ulcer of a rat model.

BACKGROUND: Wound healing is a complex biologic process that involves the integration of inflammation, mitosis, angiogenesis, synthesis, and remodeling of the extracellular matrix. However, some wounds fail to heal properly and become chronic. Although some simulated chronic wound models have been established, an efficient approach to treat chronic wounds in animal models has not been determined. The aim of this study was to develop a modified rat model simulating the chronic wounds caused by clinical radiation ulcers and examine the treatment of chronic wounds with adipose-derived stem cells. RESULTS: Sprague-Dawley rats were irradiated with an electron beam, and wounds were created. The rats received treatment with adipose-derived stem cells (ASCs), and a wound-healing assay was performed. The wound sizes after ASC treatment for 3 weeks were significantly smaller compared with the control condition (p < 0.01). Histological observations of the wound edge and immunoblot analysis of the re-epithelialization region both indicated that the treatment with ASCs was associated with the development of new blood vessels. Cell-tracking experiments showed that ASCs were colocalized with endothelial cell markers in ulcerated tissues. CONCLUSIONS: We established a modified rat model of radiation-induced wounds and demonstrated that ASCs accelerate wound-healing.

Rupture during the endovascular treatment of intracranial aneurysms: outcomes and technical aspects.

OBJECT: The purpose of this study was to determine the incidence and outcomes of intraprocedural rupture (IPR) during endovascular coil embolization of intracranial aneurysm at a single center and to explore the technical reasons and put forward corresponding preventive measures for the feared event to serve as references for other endovascular specialists. METHODS: The aneurysm database in our series was retrospectively reviewed. From April 2005 to March 2009, 176 aneurysms were consecutively treated with coils in 161 patients and IPR occurred in 12 patients. The medical records for the 12 patients were seriously examined. RESULTS: Of the 12 patients (6.8 %), four were men and eight were women with a median age of 56 years. An emergency "rescue clipping" of the lesion was carried out in two patients, parent artery occlusion was performed in two cases, endovascular treatment was terminated in one case and aneurysm coiling was rapidly completed in the remaining seven cases. Complete occlusion was achieved in nine aneurysms and incomplete occlusion in one. One patient died, yielding a mortality rate of 8.3 %. The follow-up duration was 6-30 months (median 14 months) and the mean Glasgow Outcome Scale score at the last follow-up examination was 4.3. CONCLUSIONS: The rate of IPR during endovascular coiling of intracranial aneurysms is quite low and the clinical outcome from this complication need not be catastrophic if managed appropriately. Improved operation skill and practical experience exchange among neuroradiologists are essential to lower the incidence or better patient prognoses.

Monocyte chemotactic protein-induced protein 1 (MCPIP1) suppresses stress granule formation and determines apoptosis under stress.

It is unclear how stress granule (SG) formation and cellular apoptosis are coordinately regulated. MCPIP1 (monocyte chemotactic protein-induced protein 1), also known as Zc3h12a, is a critical regulator of the inflammatory response and immune homeostasis. However, the role of MCPIP1 in stress response remains unknown. Here, we report that overexpression of MCPIP1 inhibited the assembly of SGs in response to various stresses. Conversely, MCPIP1-deficient splenocytes developed more SGs even without stress. On the other hand, overexpression of MCPIP1 sensitized RAW 264.7 cells to apoptosis under stress, whereas MCPIP1-deficient cells were resistant to stress-induced apoptosis. Mutagenesis study showed that the ability of MCPIP1 to repress SG formation is dependent on its deubiquitinating activity. Consistently, MCPIP1 negatively regulated stress-induced phosphorylation of eIF2α and thus released stress-induced inhibition of protein translation. However, MCPIP1 also inhibited 15-deoxy-Δ(12,14)-prostaglandin J(2)-induced SG formation, which was reported to be independent of eIF2α phosphorylation. Taken together, these results suggest that MCPIP1 coordinates SG formation and apoptosis during cellular stress and may play a critical role in immune homeostasis and resolution of macrophage inflammation.

Adipose-derived stem cells seeded on acellular dermal matrix grafts enhance wound healing in a murine model of a full-thickness defect.

INTRODUCTION: The promotion of wound healing using dermal substitutes has become increasingly widespread, but the outcomes of substitute-assisted healing remain functionally deficient. Adipose-derived stem cells (ASCs) have been investigated widely in regenerative medicine and tissue engineering, and they have the potential to enhance wound healing. In this study, we focused on investigating the effects and mechanism of ASCs combined with an acellular dermal matrix (ADM) to treat full-thickness cutaneous wounds in a murine model. METHODS: The ADM was prepared from the dorsal skin of nude mice by decellularization by treatment with trypsin followed by Triton X-100. The human ASCs were isolated and cultured from abdominal lipoaspirate. We created a rounded, 8-mm, full-thickness cutaneous wound in nude mice and divided the mice into the following 4 groups: silicon sheet cover only, silicon sheet with spreading ASCs, ADM only, and ASCs seeded on ADM. The granulation thickness was evaluated by histology after 7 days. Further comparisons between the ADM only and ASC-seeded ADM groups were undertaken by assessing the reepithelialization ratio and blood vessel density at postoperative days 9 and 14. Statistical analyses were conducted using Student 2-tailed t test. Immunofluorescent histology and ASC labeling were also performed to identify possible mechanisms. RESULTS: The ADM was successfully prepared, and the cytometry analysis and differentiation assay provided the characterization of the human ASCs. A marked improvement in granulation thickness was detected in the ADM-ASC group in comparison with other 3 groups. A significantly increased rate of reepithelialization in the ADM-ASC group (80 ± 6%) compared to the ADM only group (60 ± 7%) was noted on postoperative day 9. The blood vessel density was evidently increased in the ADM-ASC group (7.79 ± 0.40 vessels per field) compared to the ADM only group (5.66 ± 0.23 vessels) on day 14. Cell tracking experiments demonstrated that labeled ASCs were colocalized with staining for VEGF or endothelial cell maker vWF after the transplantation of ADM-ASCs on postoperative day 14. CONCLUSIONS: Adipose-derived stem cells seeded on an ADM can enhance wound healing, promote angiogenesis, and contribute to newly formed vasculature, and VEGF-expressing ASCs can be detected after transplantation. This model could be used to improve the other clinical applications of ASCs and to decipher the detailed mechanism by which ASCs interact with wound tissue.

NMP4 regulates the innate immune response to influenza A virus infection.

Severe influenza A virus infection typically triggers excessive and detrimental lung inflammation with massive cell infiltration and hyper-production of cytokines and chemokines. We identified a novel function for nuclear matrix protein 4 (NMP4), a zinc-finger-containing transcription factor playing roles in bone formation and spermatogenesis, in regulating antiviral immune response and immunopathology. Nmp4-deficient mice are protected from H1N1 influenza infection, losing only 5% body weight compared to a 20% weight loss in wild type mice. While having no effects on viral clearance or CD8/CD4 T cell or humoral responses, deficiency of Nmp4 in either lung structural cells or hematopoietic cells significantly reduces the recruitment of monocytes and neutrophils to the lungs. Consistent with fewer innate cells in the airways, influenza-infected Nmp4-deficient mice have significantly decreased expression of chemokine genes Ccl2, Ccl7 and Cxcl1 as well as pro-inflammatory cytokine genes Il1b and Il6. Furthermore, NMP4 binds to the promoters and/or conserved non-coding sequences of the chemokine genes and regulates their expression in mouse lung epithelial cells and macrophages. Our data suggest that NMP4 functions to promote monocyte- and neutrophil-attracting chemokine expression upon influenza A infection, resulting in exaggerated innate inflammation and lung tissue damage.

Hypoxic preconditioning protects against ischemic kidney injury through the IDO1/kynurenine pathway.

Prolonged cellular hypoxia leads to energetic failure and death. However, sublethal hypoxia can trigger an adaptive response called hypoxic preconditioning. While prolyl-hydroxylase (PHD) enzymes and hypoxia-inducible factors (HIFs) have been identified as key elements of oxygen-sensing machinery, the mechanisms by which hypoxic preconditioning protects against insults remain unclear. Here, we perform serum metabolomic profiling to assess alterations induced by two potent cytoprotective approaches, hypoxic preconditioning and pharmacologic PHD inhibition. We discover that both approaches increase serum kynurenine levels and enhance kynurenine biotransformation, leading to preservation of NAD+ in the post-ischemic kidney. Furthermore, we show that indoleamine 2,3-dioxygenase 1 (Ido1) deficiency abolishes the systemic increase of kynurenine and the subsequent renoprotection generated by hypoxic preconditioning and PHD inhibition. Importantly, exogenous administration of kynurenine restores the hypoxic preconditioning in the context of Ido1 deficiency. Collectively, our findings demonstrate a critical role of the IDO1-kynurenine axis in mediating hypoxic preconditioning.

Human cellular protein nucleoporin hNup98 interacts with influenza A virus NS2/nuclear export protein and overexpression of its GLFG repeat domain can inhibit virus propagation.

The non-structural protein NS2, also called nuclear export protein, of influenza A virus contains a leucine-rich nuclear-export signal that could guide viral ribonucleoproteins to cross the nuclear pore complex (NPC) and complete directional nucleocytoplasmic trafficking. In this study, human nucleoporin 98 (hNup98), an NPC protein, was identified as an NS2-binding protein by using yeast two-hybrid screening of a human cDNA library. Interaction between NS2 and hNup98 was confirmed in yeast and mammalian cells. Mapping tests further demonstrated that aa 22-53 in the N-terminal region of NS2 and the glycine-leucine-phenylalanine-glycine (GLFG) repeat domain (aa 1-511) of hNup98 are crucial for the interaction of these two proteins. Confocal microscopy showed that hNup98 could specifically recruit NS2 to the nucleoli and that this process was inhibited by leptomycin B, a specific inhibitor of human chromosomal region maintenance 1 protein. NS2 recruitment to the nucleoli was through the N-terminal GLFG repeat domain of hNup98, but not through the C-terminal domain. Moreover, influenza virus infection downregulated Nup98 levels significantly in 293T and Madin-Darby canine kidney cells. Overexpression of the GLFG repeat domain of hNup98 apparently inhibited virus propagation. Together, these findings reveal the interaction between hNup98 and NS2. The GLFG repeat domain of hNup98 might competitively inhibit the interaction between NS2 and endogenous hNup98, consequently inhibiting virus propagation.

Influenza A virus matrix protein 1 interacts with hTFIIIC102-s, a short isoform of the polypeptide 3 subunit of human general transcription factor IIIC.

Influenza A virus matrix protein 1 (M1) is a multifunctional protein that plays important roles during replication, assembly and budding of the virus. To search for intracellular protein components that interact with M1 protein and explore the potential roles of these interactions in the pathogenesis of influenza virus infection, 11 independent proteins, including hTFIIIC102-s protein, encoding a short isoform of the TFIIIC102 subunit of the human TFIIIC transcription factor, were screened from a human cell cDNA library using a yeast two-hybrid technique. The interaction between M1 protein and hTFIIIC102-s was studied in more detail. Mapping assays showed that the N-terminal globular region (amino acids 1-164) of the M1 protein and the five tandem tetratricopeptide repeats (TPR1-5, amino acids 149-362) in hTFIIIC102-s were necessary for the interaction. The interaction was confirmed by both glutathione-S-transferase (GST) pull-down assays and coimmunoprecipitation assays. In addition, coexpression of hTFIIIC102-s with M1 in HeLa cells inhibited the translocation of M1 into the nucleus. Taken together, the present data indicate that hTFIIIC102-s can interact with the structural M1 protein of the influenza virus, which provides a novel clue toward further understanding of the roles of M1 protein in the interactions between influenza virus and host cells.