39 research outputs found
Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells
Background: Coxsackievirus A9 (CV-A9) is a
pathogenic enterovirus type within the family Picornaviridae. CV-A9 infects A549 human epithelial lung carcinoma
cells by attaching to the aVβ6 integrin receptor through a highly conserved Arg-Gly-Asp (RGD)
motif, which is located at the exposed carboxy-terminus of the capsid protein
VP1 in all studied clinical isolates. However, genetically-modified CV-A9 that
lacks the RGD motif (CV-A9-RGDdel) has been shown to be infectious in some cell
lines but not in A549, suggesting that RGD-mediated integrin binding is not always
essential for efficient entry of CV-A9.
Methods: Two cell lines, A549 and SW480, were
used in the study. SW480 was the study object for the integrin-independent
entry and A549 was used as the control for integrin-dependent entry. Receptor
levels were quantitated by cell sorting and quantitative PCR. Antibody blocking
assay and siRNA silencing of receptor-encoding genes were used to block virus
infection. Peptide phage display library was used to identify peptide binders
to CV-A9. Immunofluorescence and confocal microscopy were used to visualize the
virus infection in the cells.
Results: We investigated the receptor use
and early stages of CV-A9 internalization to SW480 human epithelial colon
adenocarcinoma cells. Contrary to A549 infection, we showed that both CV-A9 and
CV-A9-RGDdel internalized into SW480 cells and that function-blocking anti-αV
integrin antibodies had no effect on the binding and entry of CV-A9. Whereas
siRNA silencing of β6 integrin subunit had no influence on virus infection in
SW480, silencing of β2-microglobulin (b2M) inhibited the virus infection in both cell lines. By using a peptide
phage display screening, the virus-binding peptide identical to the N-terminal
sequence of HSPA5 protein was identified and shown to block the virus infection
in both A549 and SW480 cell lines. HSPA5 was also found to co-localize with
CV-A9 at the SW480 cell periphery during the early stages of infection by
confocal microscopy.
Conclusions: The data suggest that while aVβ6 integrin is essential for CV-A9
in A549 cell line, it is not required in SW480 cell line in which β2M and HSPA5
alone are sufficient for CV-A9 infection. This suggests that the choice of
CV-A9 receptor(s) is dependent on the tissue/cellular environment.</p
Estudo da Razão de Bowen em uma Área de Floresta no Sudoeste da Amazônia
The changes mainly occurred in the hydrological cycle are associated with anthropogenic changes. In Brazil are already seen possible changes in the southwestern region that has suffered from water scarcity in their reservoirs. Understanding the Bowen ratio in the Amazon region becomes important to try to understand this ecosystem, since such information connect regional climate change. The latent heat fluxes were analyzed (λE) and sensible heat (H) in REBIO Jaru to determine the reason for Bowen and seek possible climate interactions in humid, wetdry, dry, dry-wet periods in 2009. The results observed in these periods in the Bowen ratio were 0:21; 0:24; 0:30; 0:21, and show that the forest little changes with seasonality during the year unlike the transition of biomes (Amazon - cerrado) and pasture area.As variações ocorridas principalmente no ciclo hidrológico associam-se as mudanças antrópicas. No Brasil já são vistas possíveis alterações na região sudoeste que vem sofrendo com a escassez hídrica em seus reservatórios. Compreender a razão de Bowen na região amazônica torna-se importante para tentar conhecer esse ecossistema, já que tais informações se conectam as alterações climáticas regionais. Foram analisados os fluxos de calor latente (λE) e calor sensível (H) na REBIO Jaru para determinar a razão de Bowen e buscar possíveis interações climáticas nos períodos úmido, úmido-seco, seco e seco-úmido no ano de 2009. Os resultados observados nesses períodos na razão de Bowen foram: 0.21; 0.24; 0.30; 0.21, e mostram que a floresta pouco se altera com a sazonalidade durante o ano ao contrário dos biomas de transição (Amazônia – cerrado) e da área de pastagem
The guanine nucleotide exchange factor VAV3 participates in ERBB4-mediated cancer cell migration
ERBB4 is a member of the epidermal growth factor receptor (EGFR)/ERBB subfamily of receptor tyrosine kinases that regulates cellular processes including proliferation, migration, and survival. ERBB4 signaling is involved in embryogenesis and homeostasis of healthy adult tissues, but also in human pathologies such as cancer, neurological disorders, and cardiovascular diseases. Here, an MS-based analysis revealed the Vav guanine nucleotide exchange factor 3 (VAV3), an activator of Rho family GTPases, as a critical ERBB4-interacting protein in breast cancer cells. We confirmed the ERBB4-VAV3 interaction by targeted MS and coimmunoprecipitation experiments and further defined it by demonstrating that kinase activity and Tyr-1022 and Tyr-1162 of ERBB4, as well as the intact phosphotyrosine-interacting SH2 domain of VAV3, are necessary for this interaction. We found that ERBB4 stimulates tyrosine phosphorylation of the VAV3 activation domain, known to be required for guanine nucleotide exchange factor (GEF) activity of VAV proteins. In addition to VAV3, the other members of the VAV family, VAV1 and VAV2, also coprecipitated with ERBB4. Analyses of the effects of overexpression of dominant-negative VAV3 constructs or shRNA-mediated down-regulation of VAV3 expression in breast cancer cells indicated that active VAV3 is involved in ERBB4-stimulated cell migration. These results define the VAV GEFs as effectors of ERBB4 activity in a signaling pathway relevant for cancer cell migration
Preperitoneal Fat Grafting Inhibits the Formation of Intra-abdominal Adhesions in Mice
BACKGROUND: Adhesion formation contributes to
postoperative complications in abdominal and gynaecological surgery.
Thus far, the prevention and treatment strategies have focused on
mechanical barriers in solid and liquid form, but these methods are not
in routine use. As autologous fat grafting has become popular in
treatment of hypertrophic scars because of its immunomodulatory effects,
we postulated that fat grafting could also prevent peritoneal adhesion
through similar mechanisms.METHODS: This was a control
versus intervention study to evaluate the effect of fat grafting in the
prevention on peritoneal adhesion formation. An experimental mouse model
for moderate and extensive peritoneal adhesions was used (n = 4-6
mice/group). Adhesions were induced mechanically, and a free epididymal
fat graft from wild type or CAG-DsRed mice was injected preperitoneally
immediately after adhesion induction. PET/CT imaging and scaling of the
adhesions were performed, and samples were taken for further analysis at
7 and 30 days postoperation. Macrophage phenotyping was further
performed from peritoneal lavage samples, and the expression of
inflammatory cytokines and mesothelial layer recovery were analysed from
peritoneal tissue samples.RESULTS: Fat grafting
significantly inhibited the formation of adhesions. PET/CT results did
not show prolonged inflammation in any of the groups. While the
expression of anti-inflammatory and anti-fibrotic IL-10 was
significantly increased in the peritoneum of the fat graft-treated group
at 7 days, tissue-resident and repairing M2 macrophages could no longer
be detected in the fat graft at this time point. The percentage of the
continuous, healed peritoneum as shown by Keratin 8 staining was greater
in the fat graft-treated group after 7 days.CONCLUSIONS: Fat
grafting can inhibit the formation of peritoneal adhesions in mice. Our
results suggest that fat grafting promotes the peritoneal healing
process in a paracrine manner thereby enabling rapid regeneration of the
peritoneal mesothelial cell layer.</div