Sirt1 Regulates Corneal Epithelial Migration by Deacetylating Cortactin.

Purpose: Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+) dependent deacetylase, which plays an essential role in cellular metabolism, autophagy, and chromatin accessibility. Our study aimed to determine its role in controlling corneal epithelial wound healing (CEWH). Methods: Corneal epithelial (CE)-specific Sirt1 deletion mice were created using the Cre-lox system. CE debridement was used to create a CEWH model. Corneal epithelial cells (CECs) were collected with an Algerbrush. Western blot analysis and RT-qPCR were performed to determine protein and mRNA expression levels. SiRNA transfection technology knocked down SIRT1 and cortactin expression levels in human corneal epithelial cells. Scratch wound assay, MTS assay, and TUNEL assay determined cell migratory, proliferative, and apoptotic behavior, respectively. Co-immunoprecipitation probed for SIRT1 and cortactin interaction. Immunofluorescence staining evaluated the location and expression levels of SIRT1, cortactin, acetylated-cortactin, and F-actin. Results: During CEWH, increases in SIRT1 mRNA and protein expression levels accompanied the downregulation of acetylated lysine in non-histone proteins. The loss of SIRT1 function reduced cell migration and, in turn, delayed CEWH. SIRT1 bound to and deacetylated cortactin in vitro and in vivo. Loss of either SIRT1 or cortactin suppressed wound edge lamellipodia formation, which is consistent with migration retardation. Conclusions: During CEWH, SIRT1 upregulation and its modification of cortactin boost CEC migration by increasing the development of lamellipodia at the wound edge. Therefore SIRT1 may serve as a potential target to enhance CEWH.

SIRT1 Deletion Impairs Retinal Endothelial Cell Migration Through Downregulation of VEGF-A/VEGFR-2 and MMP14.

Purpose: Silent information regulator protein 1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase that is abundantly expressed in vascular endothelial cells (VECs), and it has an essential role in angiogenesis. However, its contribution to retinal vascular development remains unclear. Here we characterize its involvement in regulating this process under both physiological and pathologic conditions. Methods: Endothelium-specific Sirt1 knockout mice were established using the Cre-lox system. VECs were isolated using magnetic beads and identified by immunostaining. Retinal whole-mount staining analyzed the retinal vascular patterns. SIRT1 was knocked down or overexpressed in human retinal microvascular endothelial cells (HRMECs) using small interfering RNA (siRNA) or lentivirus infection, respectively. Scratch assay, Transwell, and Matrigel angiogenesis assay evaluated cell migration and tube formation, respectively. Quantitative RT-PCR analyzed genes regulating VEC migration. Western blotting determined protein expression. Coimmunoprecipitation detected the interaction of hypoxia-inducible factor 1α (HIF-1α) and SIRT1 as well as acetylation status of HIF-1α. Results: Specific deletion of Sirt1 in VECs dramatically delayed retinal vessel expansion and reduced vessel density. In the oxygen-induced retinopathy (OIR) mouse model, Sirt1 ablation markedly suppressed retinal revascularization and consequently increased retinal avascularity. SIRT1 downregulation in HRMECs inhibited cell migration and tube formation, while overexpression of SIRT1 had the opposite effects. Vascular endothelial growth factor-A (VEGF-A)/VEGF receptor-2 (VEGFR-2), and matrix metalloproteinases 14 (MMP14) expression significantly declined in Sirt1-null VECs, as well as SIRT1 siRNA-transfected HRMECs. SIRT1 downregulation upregulated the HIF-1α acetylation status. Conversely, SIRT1 overexpression decreased this response. Conclusions: SIRT1 contributes to both physiological and pathologic retinal angiogenesis through promoting retinal VEC migration. Its underlying molecular mechanism involves SIRT1-mediated deacetylation of HIF-1α and subsequent upregulation of VEGF-A/VEGFR-2 and MMP14 expression.

Comparative evaluation of immunization with recombinant protein and plasmid DNA vaccines of fusion antigen ROP2 and SAG1 from Toxoplasma gondii in mice: cellular and humoral immune responses.

The aim of this work was to evaluate immune responses in BALB/c mice vaccinated subcutaneously by recombinant protein, or intramuscularly by plasmid DNA with fusion antigen of rhoptry protein 2 (ROP2) and major surface protein 1 (SAG1) from Toxoplasma gondii (T. gondii). BALB/c mice were immunized with one of three different antigen formulations respectively, which were rROP2-SAG1, pcROP2-SAG1, and pcROP2-SAG1 boosted with rROP2-SAG1. The production of IgG, IgG subclasses, lymphoproliferation, and level of gamma interferon (IFN-γ) were detected after vaccination. The animals vaccinated with rROP2-SAG1 quickly developed specific anti-TLA (T. gondii lysate antigen) antibodies, which continued to rise after immunization. However, production of IgG against TLA in mice vaccinated with pcROP2-SAG1 was relatively slow and maintained a high level after reaching plateau. There are more vigorous specific lymphoproliferative responses observed in mice of group rROP2-SAG1 than in pcROP2-SAG1. Immune responses in mice of group pcROP2-SAG1 boosted with rROP2-SAG1 were similar to the protein immunization group. Three immunization procedures resulted in a similar level of IFN-γ production. Our results indicate that BALB/c mice vaccinated by three immunization procedures induce similar humoral and cellular immunity against infection of T. gondii. Mice immunized with recombinant protein rROP2-SAG1 produce more humoral immune responses than mice immunized with other antigen formulations.

Changes in protein profiles of guinea pig sclera during development of form deprivation myopia and recovery.

PURPOSE: To investigate changes in protein profiles of posterior sclera in guinea pigs during development of form deprivation myopia and recovery. METHODS: Three groups of guinea pigs (developing form deprivation myopia, recovering from the myopia and normal control) were evaluated for protein profiles of the posterior sclera using two-dimensional gel electrophoresis. Protein spots with a different intensity of at least threefold among the 3 groups were further identified with mass spectrometry. Key proteins associated with ocular growth (crystallins) were examined at mRNA levels using RT-PCR. RESULTS: Moderate myopia was induced at 7 weeks of monocular deprivation and then more gradually recovered toward the previous refractive status 4 days after re-exposure of the eye to normal visual conditions. The profile of all protein spots at the posterior sclera was similar for both the deprived and the recovery eyes but distinct between either of the 2 experimental eyes and the normal control eyes. Twenty-six and 33 protein spots were differentially expressed in the deprived and the recovery eyes, respectively, compared to the normal control eyes. In contrast, the number of proteins differentially expressed between the deprived and the recovery eyes was only 5. Among the different subtypes of crystallins, ßB2-crystallin was down-regulated and ßA4-crystallin was upregulated in the deprived eyes at both protein and mRNA levels compared to the normal control eyes. The trend of expression for ßA3/A1-crystallin was also similar at both mRNA and protein levels for the deprived eyes. However, αA-crystallin mRNA in the recovery eyes was upregulated while αA-crystallin itself was down-regulated. A similar inconsistency in expression of ßA3/A1-, ßA4-, and ßB2-crystallins between the protein and mRNA levels also occurred in the recovery eyes. CONCLUSIONS: Proteomic analysis provides a useful survey of the number of proteins whose levels change during form deprivation myopia and the subsequent recovery. In particular, the crystallins changed during the development of form deprivation myopia and recovery. The changes in crystallin protein levels were consistent with that in mRNA levels during the development stage of form-deprivation myopia (FDM). However, the changes of most crystallin protein levels were mismatched with mRNA levels during the recovery stage.

The VP5 protein of infectious bursal disease virus promotes virion release from infected cells and is not involved in cell death.

The VP5 protein of infectious bursal disease virus (IBDV) was shown in previous reports to be involved in the cytopathogenicity of IBDV. Here, using a rescued VP5-deficient IBDV infectious clone, it was demonstrated that a lack of VP5 expression significantly hinders the release of viral progeny from infected cells but does not block intracellular virus production. Monoclonal VP5-expressing Vero cells did not exhibit induction of cell death. Using VP5-specific mAbs generated in our laboratory as a tool, it was shown by flow cytometry analysis that VP5 was detectable on the surface of IBDV-infected and monoclonal VP5-expressing Vero cells and bursal cells in IBDV-infected chickens. Taken together, these data suggest that the VP5 protein is involved in regulation of the release of intracellular IBDV virions and may be used as a cell-surface marker for detecting IBDV-infected cells in FCM analysis. This study contributes to the further characterization of the VP5 protein, which will allow a better understanding of the mechanism of IBDV pathogenicity.

Cloned Vero cell lines transfected with full-length A-segment or ORF1 cDNA sequence of IBDV.

Recombinant plasmids containing the A-segment or VP2/4/3 gene of infectious bursal disease virus (IBDV) were transfected into Vero cells. Monoclonal Vero cell lines were generated under G418 selection. Genomic (PCR/Southern blot) and transcriptional (RT-PCR/Northern blot) analyses showed that one copy of A-segment or VP2/4/3 or a partial gene of them was randomly and stably inserted into genomic DNA of Vero cells, and was able to transcribe corresponding mRNA. IFA/IPMA and Western blot analyses further confirmed that two of the monoclonal Vero cells with insertion of the A-segment of IBDV into genomic DNA could stably express VP2, VP3 and VP5 proteins, one cell line only expressed VP2 protein, and three monoclonal Vero cell lines with genomic insertion of the VP2/4/3 gene of IBDV could express VP2, VP3 and VP4 proteins. Under G418 selection, integrated foreign genes can be inherited along with cellular genomic DNA during cell replications. Moreover, DNA fragmentation and caspase-3 activity assays illustrated that cell apoptosis did not develop in monoclonal Vero cell lines expressing VP2 and VP5 proteins. The monoclonal IBDV gene-inserted Vero cell lines developed in this study will facilitate better understanding of IBDV and other members of the Birnaviridae in an expression system that would enable investigation of virus-host cell interactions on the cellular and molecular level.