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1.  The human parvovirus B19 non-structural protein 1 N-terminal domain specifically binds to the origin of replication in the viral DNA 
Virology  2013;449:297-303.
The non-structural protein 1 (NS1) of human parvovirus B19 plays a critical role in viral DNA replication. Previous studies identified the origin of replication in the viral DNA, which contains four DNA elements, namely NSBE1 to NSBE4, that are required for optimal viral replication (Guan et al, 2009, J. Virology, 83, 9541-9553). Here we have demonstrated in vitro that the NS1 N-terminal domain (NS1N) binds to the origin of replication in a sequence-specific, length-dependent manner that requires NSBE1 and NSBE2, while NSBE3 and NSBE4 are dispensable. Mutagenesis analysis has identified nucleotides in NSBE1 and NSBE2 that are critical for NS1N binding. These results suggest that NS1 binds to the NSBE1-NSBE2 region in the origin of replication, while NSBE3 and NSBE4 may provide binding sites for potential cellular factors. Such a specialized nucleoprotein complex may enable NS1 to nick the terminal resolution site and separate DNA strands during replication.
PMCID: PMC3953040  PMID: 24418564
parvovirus; B19; non-structural protein 1; origin of replication; protein:DNA interaction
2.  Human bocavirus 1 infects commercially-available primary human airway epithelium cultures productively 
Journal of virological methods  2013;195:10.1016/j.jviromet.2013.10.012.
Human bocavirus 1 (HBoV1), a human parvovirus, belongs to the genus Bocavirus of the Parvoviridae family. It causes wheezing in young children with acute respiratory tract infections. HBoV1 has been shown to infect polarized human airway epithelium (HAE) made in house, and induces airway epithelial damage. In this study, two commercially-available HAE cultures, EpiAirway and MucilAir HAE, were examined for HBoV1 infection. Both HAE cultures support fully productive HBoV1 infection. Infected EpiAirway and MucilAir HAE cultures showed loss of cilia, disruption of the tight junction barrier, and a significant decrease in transepithelial electrical resistance. Notably, HBoV1 persistent infection was demonstrated by maintaining HBoV1-infected EpiAirway HAE for as long as 50 days. After 2 days post-infection, progeny virus was produced consistently daily at a level of over 2 × 108 viral genome copies per culture (0.6 cm2). This study is the first to use commercial sources of HAE cultures for HBoV1 infection. The availability of these cultures will enable a wide range of laboratories to study HBoV1 infection.
PMCID: PMC3855471  PMID: 24134939
3.  Novel Amdoparvovirus Infecting Farmed Raccoon Dogs and Arctic Foxes 
Emerging Infectious Diseases  2014;20(12):2085-2088.
A new amdoparvovirus, named raccoon dog and fox amdoparvovirus (RFAV), was identified in farmed sick raccoon dogs and arctic foxes. Phylogenetic analyses showed that RFAV belongs to a new species within the genus Amdoparvovirus of the family Parvoviridae. An RFAV strain was isolated in Crandell feline kidney cell culture.
PMCID: PMC4257837  PMID: 25417672
amdoparvovirus; infection; raccoon dog (Nyctereutes procyonoides); Arctic fox (Vulpes lagopus); viruses; China
4.  Parvovirus infection-induced DNA damage response 
Future virology  2013;8(3):245-257.
Parvoviruses are a group of small DNA viruses with ssDNA genomes flanked by two inverted terminal structures. Due to a limited genetic resource they require host cellular factors and sometimes a helper virus for efficient viral replication. Recent studies have shown that parvoviruses interact with the DNA damage machinery, which has a significant impact on the life cycle of the virus as well as the fate of infected cells. In addition, due to special DNA structures of the viral genomes, parvoviruses are useful tools for the study of the molecular mechanisms underlying viral infection-induced DNA damage response (DDR). This review aims to summarize recent advances in parvovirus-induced DDR, with a focus on the diverse DDR pathways triggered by different parvoviruses and the consequences of DDR on the viral life cycle as well as the fate of infected cells.
PMCID: PMC4242421  PMID: 25429305
adeno-associated virus; bocavirus; DNA damage response; minute virus of canines; minute virus of mice; parvovirus; parvovirus B19; parvovirus H-1
5.  Differential virus restriction patterns of rhesus macaque and human APOBEC3A: implications for lentivirus evolution 
Virology  2011;419(1):24-42.
The human apolipoprotein B mRNA editing enzyme catalytic peptide-like 3 (APOBEC3;A3) family of proteins (A3A-H) are known to restrict various retroviruses and retroelements, but the full complement of rhesus macaque A3 proteins remains unclear. We report the isolation and characterization of the hA3A homologue from rhesus macaques (rhA3A) and show that the rhesus macaque and human A3 genes are orthologous. RhA3A is expressed at high levels in activated CD4+ T cells, is widely expressed in macaque tissues, and is degraded in the presence of the human immunodeficiency virus (HIV-1) and simian-human immunodeficiency virus (SHIV) genomes. Our results indicate that rhA3A is a potent inhibitor of SHIVΔvif and to a lesser extent HIV-1Δvif. Unlike hA3A, rhA3A did not inhibit adeno-associated virus 2 (AAV-2) replication and L1 retrotransposition. These data suggest an evolutionary switch in primate A3A virus specificity and provide the first evidence that a primate A3A can inhibit lentivirus replication.
PMCID: PMC4104698  PMID: 21868050
6.  Human Parvovirus B19 Infection Causes Cell Cycle Arrest of Human Erythroid Progenitors at Late S Phase That Favors Viral DNA Replication 
Journal of Virology  2013;87(23):12766-12775.
Human parvovirus B19 (B19V) infection has a unique tropism to human erythroid progenitor cells (EPCs) in human bone marrow and the fetal liver. It has been reported that both B19V infection and expression of the large nonstructural protein NS1 arrested EPCs at a cell cycle status with a 4 N DNA content, which was previously claimed to be “G2/M arrest.” However, a B19V mutant infectious DNA (M20mTAD2) replicated well in B19V-semipermissive UT7/Epo-S1 cells but did not induce G2/M arrest (S. Lou, Y. Luo, F. Cheng, Q. Huang, W. Shen, S. Kleiboeker, J. F. Tisdale, Z. Liu, and J. Qiu, J. Virol. 86:10748–10758, 2012). To further characterize cell cycle arrest during B19V infection of EPCs, we analyzed the cell cycle change using 5-bromo-2′-deoxyuridine (BrdU) pulse-labeling and DAPI (4′,6-diamidino-2-phenylindole) staining, which precisely establishes the cell cycle pattern based on both cellular DNA replication and nuclear DNA content. We found that although both B19V NS1 transduction and infection immediately arrested cells at a status of 4 N DNA content, B19V-infected 4 N cells still incorporated BrdU, indicating active DNA synthesis. Notably, the BrdU incorporation was caused neither by viral DNA replication nor by cellular DNA repair that could be initiated by B19V infection-induced cellular DNA damage. Moreover, several S phase regulators were abundantly expressed and colocalized within the B19V replication centers. More importantly, replication of the B19V wild-type infectious DNA, as well as the M20mTAD2 mutant, arrested cells at S phase. Taken together, our results confirmed that B19V infection triggers late S phase arrest, which presumably provides cellular S phase factors for viral DNA replication.
PMCID: PMC3838147  PMID: 24049177
7.  Structure of the NS1 Protein N-Terminal Origin Recognition/Nickase Domain from the Emerging Human Bocavirus 
Journal of Virology  2013;87(21):11487-11493.
Human bocavirus is a newly identified, globally prevalent, parvovirus that is associated with respiratory infection in infants and young children. Parvoviruses encode a large nonstructural protein 1 (NS1) that is essential for replication of the viral single-stranded DNA genome and DNA packaging and may play versatile roles in virus-host interactions. Here, we report the structure of the human bocavirus NS1 N-terminal domain, the first for any autonomous parvovirus. The structure shows an overall fold that is canonical to the histidine-hydrophobic-histidine superfamily of nucleases, which integrates two distinct DNA-binding sites: (i) a positively charged region mediated by a surface hairpin (residues 190 to 198) that is responsible for recognition of the viral origin of replication of the double-stranded DNA nature and (ii) the nickase active site that binds to the single-stranded DNA substrate for site-specific cleavage. The structure reveals an acidic-residue-rich subdomain that is present in bocavirus NS1 proteins but not in the NS1 orthologs in erythrovirus or dependovirus, which may mediate bocavirus-specific interaction with DNA or potential host factors. These results provide insights into recognition of the origin of replication and nicking of DNA during bocavirus genome replication. Mapping of variable amino acid residues of NS1s from four human bocavirus species onto the structure shows a scattered pattern, but the origin recognition site and the nuclease active site are invariable, suggesting potential targets for antivirals against this clade of highly diverse human viruses.
PMCID: PMC3807368  PMID: 23966383
8.  Human Phosphatidylethanolamine-Binding Protein 4 Promoted the Radioresistance of Human Rectal Cancer by Activating Akt in an ROS-Dependent Way 
PLoS ONE  2014;9(3):e90062.
Human phosphatidylethanolamine-binding protein 4(hPEBP4) is a novel anti-apoptosis molecule associated with the resistance of tumors to apoptotic agents. Here we sought to investigate the role of hPEBP4 in the radioresistance of rectal cancer. Immunohistochemistry analysis showed hPEBP4 was expressed in 27/33 of rectal cancer specimens, but only in 2/33 of neighboring normal mucosa. Silencing the expression of hPEBP4 with siRNA significantly reduced the clonogenic survival and enhanced the apoptosis of rectal cancer cells on irradiation. Instead, forced overexpression of hPEBP4 promoted its survival and decreased the apoptosis. Western blot showed hPEBP4 could increase the radiation-induced Akt activation, for which reactive oxygen specimen(ROS) was required. The radioresistance effect of hPEBP4 was reversed after given LY-294002 to inhibit Akt activation or antioxidant to abolish the ROS production. We also confirmed that effect of hPEBP4 in vivo with nude mice. Thus we concluded that hPEBP4, specifically expressed in rectal cancer cells, is associated with radioresistance of rectal cancer, implying that modulation of hPEBP4 may have important therapeutic implications in radiotherapy of rectal cancer.
PMCID: PMC3940727  PMID: 24594691
9.  An experimental research into endostatin microbubble combined with focused ultrasound for anti-tumor angiogenesis in colon cancer 
Gastroenterology Report  2014;2(1):44-53.
Objective: to evaluate the therapeutic effect of targeted endostatin-loaded microbubbles, combined with improved, focused, directional ultrasound radiation for inhibition of subcutaneous translocation in situ colon tumor angiogenesis in colon cancer.
Methods: 65 BALB/c nude mice with subcutaneous translocation in situ colon tumors were randomly divided into five groups. Group A was the control group, without any treatments. In Group B, the mouse was treated with ultrasonic radiation. In Group C, the mouse was treated with ultrasonic radiation combined with empty SonoVue microbubbles. In Group D, the mouse was treated with ultrasonic radiation combined with empty Targestar-SA microbubbles. In Group E, the mouse was treated with ultrasonic radiation combined with endostatin microbubbles. The tumor size was measured before and 1, 14, and 28 days after irradiation. The peak intensity (PI), regional blood volume (RBV) and regional blood flow (RBF) were recorded using contrast-enhanced ultrasound. The tumor tissue was removed for pathological examination; the tumor necrosis area and microvascular density (MVD) were evaluated by immunohistochemistry.
Results: Tumors in Groups C, D and E were significantly smaller than in Groups A and B at 28 days after irradiation, with Group E the smallest. PI, RBF and RBV of Groups C, D, and E were significantly decreased 28 days after radiation with Group E the lowest, and significantly lower than Groups A and B (all P < 0.05). The tumor tissue necrosis area of Group E was clearly greater while MVD was obviously lower than the other groups (all P < 0.01) at 28 days after treatment.
Conclusion: The targeted endostatin microbubbles, combined with focused, directional ultrasound radiation can damage tumor microvasculature of subcutaneous colon translocation in situ colon cancer, as well as inhibit the tumor angiogenesis.
PMCID: PMC3920996  PMID: 24760236
colorectal cancer; tumor angiogenesis; ultrasonic cavitation; endostatin
10.  Disease progression in iridocorneal angle tissues of BMP2-induced ocular hypertensive mice with optical coherence tomography 
Molecular Vision  2014;20:1695-1709.
The goal of the present study was to test for the first time whether glaucomatous-like disease progression in a mouse can be assessed morphologically and functionally with spectral domain optical coherence tomography (SD-OCT).
We monitored progressive changes in conventional outflow tissues of living mice overexpressing human bone morphogenetic protein 2 (BMP2), a model for glaucoma. Intraocular pressure (IOP) and outflow tissue morphology/Young's modulus were followed in mice for 36 days with rebound tonometry and SD-OCT, respectively. Results were compared to standard histological methods. Outflow facility was calculated from flow measurements with direct cannulation of anterior chambers subjected to three sequential pressure steps.
Overexpression of BMP2 significantly elevated IOP in a biphasic manner over time compared to mice that overexpressed green fluorescent protein in outflow cells and naïve controls. SD-OCT revealed changes in outflow tissues overexpressing BMP2 that corresponded with the timing of the IOP phases and decreased outflow facility. In the first phase, the angle was open, but the trabecular meshwork and the cornea were thickened. OCT detected increased trabecular meshwork stiffness after provocative IOP challenges of the BMP2 eyes, which corresponded to increased collagen deposition with transmission electron microscopy. In contrast, the angle was closed in the second phase. IOP elevation over 36 days due to BMP2 overexpression resulted in significant retinal ganglion cell and axon loss.
Although not a feasible open-angle glaucoma model, the BMP2 mice were useful for demonstrating the utility of SD-OCT in following disease progression and differentiating between two forms of ocular pathology over time that resulted in ocular hypertension.
PMCID: PMC4279588  PMID: 25558173
11.  SMC1-Mediated Intra-S-Phase Arrest Facilitates Bocavirus DNA Replication 
Journal of Virology  2013;87(7):4017-4032.
Activation of a host DNA damage response (DDR) is essential for DNA replication of minute virus of canines (MVC), a member of the genus Bocavirus of the Parvoviridae family; however, the mechanism by which DDR contributes to viral DNA replication is unknown. In the current study, we demonstrate that MVC infection triggers the intra-S-phase arrest to slow down host cellular DNA replication and to recruit cellular DNA replication factors for viral DNA replication. The intra-S-phase arrest is regulated by ATM (ataxia telangiectasia-mutated kinase) signaling in a p53-independent manner. Moreover, we demonstrate that SMC1 (structural maintenance of chromosomes 1) is the key regulator of the intra-S-phase arrest induced during infection. Either knockdown of SMC1 or complementation with a dominant negative SMC1 mutant blocks both the intra-S-phase arrest and viral DNA replication. Finally, we show that the intra-S-phase arrest induced during MVC infection was caused neither by damaged host cellular DNA nor by viral proteins but by replicating viral genomes physically associated with the DNA damage sensor, the Mre11-Rad50-Nbs1 (MRN) complex. In conclusion, the feedback loop between MVC DNA replication and the intra-S-phase arrest is mediated by ATM-SMC1 signaling and plays a critical role in MVC DNA replication. Thus, our findings unravel the mechanism underlying DDR signaling-facilitated MVC DNA replication and demonstrate a novel strategy of DNA virus-host interaction.
PMCID: PMC3624210  PMID: 23365434
12.  In Vitro Modeling of Human Bocavirus 1 Infection of Polarized Primary Human Airway Epithelia 
Journal of Virology  2013;87(7):4097-4102.
Human bocavirus 1 (HBoV1) is an emerging human-pathogenic respiratory virus. We characterized two important features of HBoV1 infection in polarized primary human airway epithelia (HAE). Apical HBoV1 infection of HAE at a low multiplicity of infection causes disruption of the tight junction barrier, loss of cilia, and epithelial cell hypertrophy, which are hallmarks of the airway epithelial damage caused by HBoV1 infection. HBoV1 also infects HAE from the basolateral surface productively, although less efficiently, and this also leads to the characteristic airway epithelial damage.
PMCID: PMC3624236  PMID: 23345515
13.  Protective Effects of Resveratrol in Experimental Retinal Detachment 
PLoS ONE  2013;8(9):e75735.
Oxidative stress is one of the major factors that trigger photoreceptor apoptosis. To investigate whether resveratrol, a potent antioxidant and small molecule activator of the FoxO pathway, would be neuroprotective against photoreceptor cell death in a rodent model of retinal detachment.
Retinal detachment was created in adult Brown Norway rats by subretinal injection of sodium hyaluronate. The animals were treated daily with vehicle or resveratrol (20mg/kg) intraperitoneal injection. Photoreceptor death was assessed by counting the number of apoptotic cells with TdT-dUTP terminal nick-end labeling (TUNEL) and measurement of the outer nuclear layer (ONL) thickness 3 days after RD. Changes in expression of FoxO1a, FoxO3a, and FoxO4 were analyzed by western blot. The activity of caspase 3, caspase 8, caspase 9, spectrin and their cleavage forms were studied.
Three days after retinal detachment, caspase 3, caspase 8 and caspase 9 were significantly activated in the detached retina. Spectrin cleavage products at 120 and 145 kDa were also detected. Both caspase and calpain activation are involved in apoptotic photoreceptor cell death in detached retinas. Treatment with resveratrol increases FoxO1a, FoxO3a, and FoxO4 protein expression in detached retinas only. Resveratrol treatment decreases activation of intrinsic and extrinsic caspase apoptotic pathways triggered by RD. The number of TUNEL-positive cells decreases from 1301±51 cells/mm2 in control groups to 430±35 cells/mm2 in treatment groups (p<0.05). Resveratrol treatment also demonstrates 59% less ONL thickness loss compared to controls.
Resveratrol treatment up-regulates the FoxO family and blocks Caspase3, 8, and 9 activation. Resveratrol has the potential to be used as a novel therapeutic agent for preventing vision loss in diseases characterized by photoreceptor detachment.
PMCID: PMC3770540  PMID: 24040416
14.  Characterization of the Nonstructural Proteins of the Bocavirus Minute Virus of Canines 
Journal of Virology  2013;87(2):1098-1104.
We present a detailed characterization of a single-cycle infection of the bocavirus minute virus of canines (MVC) in canine WRD cells. This has allowed identification of an additional smaller NS protein that derives from an mRNA spliced within the NS gene that had not been previously reported. In addition, we have identified a role for the viral NP1 protein during infection. NP1 is required for read-through of the MVC internal polyadenylation site and, thus, access of the capsid gene by MVC mRNAs. Although the mechanism of NP1's action has not yet been fully elucidated, it represents the first parvovirus protein to be implicated directly in viral RNA processing.
PMCID: PMC3554049  PMID: 23135724
15.  The Determinants for the Enzyme Activity of Human Parvovirus B19 Phospholipase A2 (PLA2) and Its Influence on Cultured Cells 
PLoS ONE  2013;8(4):e61440.
Human parvovirus B19 (B19V) is the causative agent of erythema infectiosum in humans. B19 infection also causes severe disease manifestations, such as chronic anemia in immunocompromised patients, aplastic crisis in patients with a high turnover rate of red blood cells, and hydrops fetalis in pregnant women. Although a secreted phospholipase A2 (PLA2) motif has been identified in the unique region of the B19V minor capsid protein VP1(VP1u), the determinants for its enzyme activity and its influences on host cells are not well understood. The purpose of this study was to investigate the contribution of the PLA2 motif and other regions of the VP1u to the PLA2 activity, to determine the cellular localization of the VP1u protein, and to examine the effects of VP1u on cellular cytokines. We found that in addition to the critical conserved and non-conserved amino acids within the VP1u PLA2 motif, amino acid residues outside the VP1u PLA2 motif are also important for the PLA2 activity. VP1u and various mutants all revealed a nucleo-cytoplasmic distribution. UT7-Epo cells treated with prokaryotic expressed VP1u or mutant proteins with PLA2 activity released a large amount of free fatty acid (FFA), and the cell morphological change occurred dramatically. However, neither free fatty acid nor cell morphology change occurred for cells treated with the mutants without PLA2 activity. The wild type and the VP1u mutants with the PLA2 activity also activated TNF-α promoter and upregulated the transcription activity of NF-κB in transfected cells. In addition, we found that the amino acids outside the PLA2 domain are critical for the viral PLA2 activity, and that these tested VP1u mutants did not affect the localization of the VP1u protein.
PMCID: PMC3626588  PMID: 23596524
16.  Human Parvovirus B19 DNA Replication Induces a DNA Damage Response That Is Dispensable for Cell Cycle Arrest at Phase G2/M 
Journal of Virology  2012;86(19):10748-10758.
Human parvovirus B19 (B19V) infection is highly restricted to human erythroid progenitor cells, in which it induces a DNA damage response (DDR). The DDR signaling is mainly mediated by the ATR (ataxia telangiectasia-mutated and Rad3-related) pathway, which promotes replication of the viral genome; however, the exact mechanisms employed by B19V to take advantage of the DDR for virus replication remain unclear. In this study, we focused on the initiators of the DDR and the role of the DDR in cell cycle arrest during B19V infection. We examined the role of individual viral proteins, which were delivered by lentiviruses, in triggering a DDR in ex vivo-expanded primary human erythroid progenitor cells and the role of DNA replication of the B19V double-stranded DNA (dsDNA) genome in a human megakaryoblastoid cell line, UT7/Epo-S1 (S1). All the cells were cultured under hypoxic conditions. The results showed that none of the viral proteins induced phosphorylation of H2AX or replication protein A32 (RPA32), both hallmarks of a DDR. However, replication of the B19V dsDNA genome was capable of inducing the DDR. Moreover, the DDR per se did not arrest the cell cycle at the G2/M phase in cells with replicating B19V dsDNA genomes. Instead, the B19V nonstructural 1 (NS1) protein was the key factor in disrupting the cell cycle via a putative transactivation domain operating through a p53-independent pathway. Taken together, the results suggest that the replication of the B19V genome is largely responsible for triggering a DDR, which does not perturb cell cycle progression at G2/M significantly, during B19V infection.
PMCID: PMC3457271  PMID: 22837195
17.  A novel bocavirus in canine liver 
Virology Journal  2013;10:54.
Bocaviruses are classified as a genus within the Parvoviridae family of single-stranded DNA viruses and are pathogenic in some mammalian species. Two species have been previously reported in dogs, minute virus of canines (MVC), associated with neonatal diseases and fertility disorders; and Canine bocavirus (CBoV), associated with respiratory disease.
In this study using deep sequencing of enriched viral particles from the liver of a dog with severe hemorrhagic gastroenteritis, necrotizing vasculitis, granulomatous lymphadenitis and anuric renal failure, we identified and characterized a novel bocavirus we named Canine bocavirus 3 (CnBoV3). The three major ORFs of CnBoV3 (NS1, NP1 and VP1) shared less than 60% aa identity with those of other bocaviruses qualifying it as a novel species based on ICTV criteria. Inverse PCR showed the presence of concatemerized or circular forms of the genome in liver.
We genetically characterized a bocavirus in a dog liver that is highly distinct from prior canine bocaviruses found in respiratory and fecal samples. Its role in this animal’s complex disease remains to be determined.
PMCID: PMC3577433  PMID: 23402347
Canine bocavirus 3; Episome; Coinfection
18.  Molecular Characterization of the Newly Identified Human Parvovirus 4 in the Family Parvoviridae 
Virology  2011;422(1):59-69.
Human parvovirus 4 (PARV4) is an emerging human virus, and little is known about the molecular aspects of PARV4 apart from its incomplete genome sequence, which lacks information of the termini. We analyzed the gene expression profile of PARV4 using a nearly full-length HPV4 genome in a replication competent system in 293 cells. We found that PARV4 utilizes two promoters to transcribe non-structural protein- and structural protein-encoding mRNAs, respectively, which were polyadenylated at the right end of the genome. Three major proteins, including the large non-structural protein NS1a, whose mRNA is spliced, and capsid proteins VP1 and VP2, were detected. Additional functional analysis of the NS1a revealed its capability to induce cell cycle arrest at G2/M phase in ex vivo-generated human hematopoietic stem cells. Taken together, our characterization of the molecular features of PARV4 suggests that PARV4 represents a new genus in the family Parvoviridae.
PMCID: PMC3229647  PMID: 22044541
19.  Regulation of Trabecular Meshwork Cell Contraction and Intraocular Pressure by miR-200c 
PLoS ONE  2012;7(12):e51688.
Lowering intraocular pressure (IOP) delays or prevents the loss of vision in primary open-angle glaucoma (POAG) patients with high IOP and in those with normal tension glaucoma showing progression. Abundant evidence demonstrates that inhibition of contractile machinery of the trabecular meshwork cells is an effective method to lower IOP. However, the mechanisms involved in the regulation of trabecular contraction are not well understood. Although microRNAs have been shown to play important roles in the regulation of multiple cellular functions, little is known about their potential involvement in the regulation of IOP. Here, we showed that miR-200c is a direct postranscriptional inhibitor of genes relevant to the physiologic regulation of TM cell contraction including the validated targets Zinc finger E-box binding homeobox 1 and 2 (ZEB1 and ZEB2), and formin homology 2 domain containing 1 (FHOD1), as well as three novel targets: lysophosphatidic acid receptor 1 (LPAR1/EDG2), endothelin A receptor (ETAR), and RhoA kinase (RHOA). Consistently, transfection of TM cells with miR-200c resulted in strong inhibition of contraction in collagen populated gels as well as decreased cell traction forces exerted by individual TM cells. Finally, delivery of miR-200c to the anterior chamber of living rat eyes resulted in a significant decrease in IOP, while inhibition of miR-200c using an adenoviral vector expressing a molecular sponge led to a significant increase in IOP. These results demonstrate for the first time the ability of a miRNA to regulate trabecular contraction and modulate IOP in vivo, making miR-200c a worthy candidate for exploring ways to alter trabecular contractility with therapeutic purposes in glaucoma.
PMCID: PMC3522713  PMID: 23272142
20.  Genomic features of the human bocaviruses 
Future virology  2012;7(1):31-39.
The human bocavirus (HBoV) was initially discovered in 2005 as the second pathogenic member of the parvovirus family, next to the human parvovirus B19. HBoV has since been shown to be extremely common worldwide and to cause a systemic infection in small children often resulting in respiratory disease. Three more, presumably enteric, human bocaviruses (HBoV2–4) have been identified in stool samples. Parvoviruses are assumed to replicate via their genomic terminal hairpin-like structures in a so-called ‘rolling-hairpin model’. These terminal sequences have recently been partially identified in head-to-tail HBoV-PCR amplicons from clinical samples, and are most likely hybrid relics of HBoV’s predecessors, namely bovine parvovirus 1 on the left-hand side and minute virus of canines on the right, shown for the first time in this article. Thereby, the replication model postulated for HBoV remains questionable as the occurrence of head-to-tail sequences is not a typical feature of the rolling-hairpin replication model. However, such episomes can also be persistent storage forms of the genome.
PMCID: PMC3291126  PMID: 22389649
genome structure; hairpin sequence; HBoV; human bocavirus; parvovirus; persistence; replication; transcription map
21.  Establishment of a Reverse Genetics System for Studying Human Bocavirus in Human Airway Epithelia 
PLoS Pathogens  2012;8(8):e1002899.
Human bocavirus 1 (HBoV1) has been identified as one of the etiological agents of wheezing in young children with acute respiratory-tract infections. In this study, we have obtained the sequence of a full-length HBoV1 genome (including both termini) using viral DNA extracted from a nasopharyngeal aspirate of an infected patient, cloned the full-length HBoV1 genome, and demonstrated DNA replication, encapsidation of the ssDNA genome, and release of the HBoV1 virions from human embryonic kidney 293 cells. The HBoV1 virions generated from this cell line-based production system exhibits a typical icosahedral structure of approximately 26 nm in diameter, and is capable of productively infecting polarized primary human airway epithelia (HAE) from the apical surface. Infected HAE showed hallmarks of lung airway-tract injury, including disruption of the tight junction barrier, loss of cilia and epithelial cell hypertrophy. Notably, polarized HAE cultured from an immortalized airway epithelial cell line, CuFi-8 (originally derived from a cystic fibrosis patient), also supported productive infection of HBoV1. Thus, we have established a reverse genetics system and generated the first cell line-based culture system for the study of HBoV1 infection, which will significantly advance the study of HBoV1 replication and pathogenesis.
Author Summary
Human bocavirus 1 (HBoV1) has been identified as one of the etiological agents of wheezing in young children with acute respiratory-tract infections. HBoV1 productively infects polarized primary human airway epithelia. However, no cell lines permissive to HBoV1 infection have yet been established. More importantly, the sequences at both ends of the HBoV1 genome have remained unknown. We have resolved both of these issues in this study. We have sequenced a full-length HBoV1 genome and cloned it into a plasmid. We further demonstrated that this HBoV1 plasmid replicated and produced viruses in human embryonic kidney 293 cells. Infection of these HBoV1 progeny virions produced obvious cytopathogenic effects in polarized human airway epithelia, which were represented by disruption of the epithelial barrier. Moreover, we identified an airway epithelial cell line supporting HBoV1 infection, when it was polarized. This is the first study to obtain the full-length HBoV1 genome, to demonstrate pathogenesis of HBoV1 infection in human airway epithelia, and to identify the first cell line to support productive HBoV1 infection.
PMCID: PMC3431310  PMID: 22956907
22.  Parvovirus B19 Infection of Human Primary Erythroid Progenitor Cells Triggers ATR-Chk1 Signaling, Which Promotes B19 Virus Replication ▿  
Journal of Virology  2011;85(16):8046-8055.
Human parvovirus B19 (B19V) infection is restricted to erythroid progenitor cells of the human bone marrow. Although the mechanism by which the B19V genome replicates in these cells has not been studied in great detail, accumulating evidence has implicated involvement of the cellular DNA damage machinery in this process. Here, we report that, in ex vivo-expanded human erythroid progenitor cells, B19V infection induces a broad range of DNA damage responses by triggering phosphorylation of all the upstream kinases of each of three repair pathways: ATM (ataxia-telangiectasi mutated), ATR (ATM and Rad3 related), and DNA-PKcs (DNA-dependent protein kinase catalytic subunit). We found that phosphorylated ATM, ATR, and DNA-PKcs, and also their downstream substrates and components (Chk2, Chk1, and Ku70/Ku80 complex, respectively), localized within the B19V replication center. Notably, inhibition of kinase phosphorylation (through treatment with either kinase-specific inhibitors or kinase-specific shRNAs) revealed requirements for signaling of ATR and DNA-PKcs, but not ATM, in virus replication. Inhibition of the ATR substrate Chk1 led to similar levels of decreased virus replication, indicating that signaling via the ATR-Chk1 pathway is critical to B19V replication. Notably, the cell cycle arrest characteristic of B19V infection was not rescued by interference with the activity of any of the three repair pathway kinases.
PMCID: PMC3147961  PMID: 21680529
23.  Role of miR-204 in the Regulation of Apoptosis, Endoplasmic Reticulum Stress Response, and Inflammation in Human Trabecular Meshwork Cells 
The authors report the identification of novel gene targets of miR-204 and show that this microRNA may play an important role in the regulation of multiple functions in human trabecular meshwork cells, including apoptosis, accumulation of damaged proteins, endoplasmic reticulum stress response, and expression of inflammatory mediators.
To investigate the biological functions of miR-204 in human trabecular meshwork (HTM) cells.
Changes in gene expression induced by miR-204 in HTM cells were evaluated by gene array analysis using arrays and confirmed by quantitative-PCR (Q-PCR). Direct targeting of miR-204 to 12 potential novel targets was confirmed using a luciferase system, and five of them were verified by Western blot analysis. Effects of miR-204 on apoptosis, cell viability, and accumulation of carbonylated proteins were evaluated in HTM cells treated with H2O2. Induction of endoplasmic reticulum (ER) stress markers by tunicamycin was analyzed by Q-PCR, and expression of IL-8 and IL-11 was analyzed by ELISA.
MiR-204 decreased the expression of multiple genes in HTM cells. Twelve genes (AP1S2, Bcl2l2, BIRC2, EDEM1, EZR, FZD1, M6PR, RAB22A, RAB40B, SERP1, TCF12, and TCF4) were validated as direct targets of miR-204. Downregulation of expressions at protein levels of Bcl2l2, BIRC2, EZR, M6PR, and SERP1 were confirmed by Western blot analysis. HTM cells transfected with miR-204 showed increased levels of apoptosis, decreased viability, increased accumulation of oxidized proteins after H2O2 treatment, decreased induction of ER stress response markers, and reduced expression of inflammatory mediators IL-8 and IL-11.
MiR-204 potentially plays an important role in the regulation of multiple functions in HTM cells including apoptosis, accumulation of damaged proteins, ER stress response, and expression of inflammatory mediators.
PMCID: PMC3109013  PMID: 21282569
24.  Cross-talk between miR-29 and Transforming Growth Factor-Betas in Trabecular Meshwork Cells 
Interactions between TGFβs and miR-29b might play an important role in the modulation of ECM dynamics in trabecular meshwork cells. Specifically, downregulation of miR-29 by TGFβ2 could contribute to some of the effects mediated by this cytokine in the trabecular meshwork.
To investigate the interactions between microRNA-29 (miR-29), a negative regulator of extracellular matrix (ECM), and transforming growth factors (TGF)β-1 and TGFβ-2.
Changes in expression of the miR-29 family were analyzed by quantitative-PCR (Q-PCR) after treatment with TGFβ1 and TGFβ2 (1 ng/mL). TGFβ1 and TGFβ2 were evaluated at gene expression and protein levels by Q-PCR and ELISA, respectively, in human trabecular meshwork (HTM) cells transfected with miR-29b or scramble control. TGFβ1 promoter activity was analyzed using an adenovirus with the reporter SEAP. The effects of miR-29b and TGFβ2 on ECM gene expression were evaluated in cells transfected with miR-29b or scramble control and treated with TGFβ2, and the expression of ECM genes was analyzed by Q-PCR.
TGFβ2 but not TGFβ1, downregulated the three members of the miR-29 family. Overexpression of miR-29b antagonized the effects of TGFβ2 on the expression of several ECM components. MiR-29b decreased the expression of TGFβ1 at the promoter, transcript, and protein levels but had only a minor effect on the expression of active TGFβ2. The inhibition of TGFβ1 by miR-29b was partially recovered after co-transfection with a plasmid-expressing bone morphogenetic protein 1.
Results showed some level of crosstalk between TGFβs and miR-29. Specifically, the downregulation of miR-29 by TGFβ2 contributed to the induction of several ECM components by this cytokine in TM cells. This observation, together with the inhibitory effects of miR-29b on the expression of TGFβ1, suggests that the miR-29 family could play an important role in modulating TGFβs on the outflow pathway.
PMCID: PMC3109042  PMID: 21273536
25.  Inclusion of the Central Exon of Parvovirus B19 Precursor mRNA Is Determined by Multiple Splicing Enhancers in both the Exon and the Downstream Intron ▿  
Journal of Virology  2010;85(5):2463-2468.
Alternative splicing of the precursor mRNA (pre-mRNA) of human parvovirus B19 (B19V) plays a key role in posttranscriptional regulation of B19V gene expression. We report that the central exon of the B19V pre-mRNA is defined by three GAA motif-containing exonic splicing enhancers and a G/GU-rich intronic splicing enhancer that lies adjacent to the second donor site. Moreover, targeting of morpholino antisense oligonucleotides to the two splicing enhancers surrounding the second donor site led to a significant reduction in splicing at this donor site during B19V infection of permissive CD36+ erythroid progenitor cells.
PMCID: PMC3067811  PMID: 21159861

Results 1-25 (61)