Impairment of T cell development and acute inflammatory response in HIV-1 Tat transgenic mice

Immune activation and chronic inflammation are hallmark features of HIV infection causing T-cell depletion and cellular immune dysfunction in AIDS. Here, we addressed the issue whether HIV-1 Tat could affect T cell development and acute inflammatory response by generating a transgenic mouse expressing Tat in lymphoid tissue. Tat-Tg mice showed thymus atrophy and the maturation block from DN4 to DP thymic subpopulations, resulting in CD4(+) and CD8(+) T cells depletion in peripheral blood. In Tat-positive thymus, we observed the increased p65/NF-κB activity and deregulated expression of cytokines/chemokines and microRNA-181a-1, which are involved in T-lymphopoiesis. Upon LPS intraperitoneal injection, Tat-Tg mice developed an abnormal acute inflammatory response, which was characterized by enhanced lethality and production of inflammatory cytokines. Based on these findings, Tat-Tg mouse could represent an animal model for testing adjunctive therapies of HIV-1-associated inflammation and immune deregulation

In situ cross-linkable novel alginate-dextran methacrylate IPN hydrogels for biomedical applications: Mechanical characterization and drug delivery properties

In situ polymerizable hydrogels are extensively investigated to implement new biomedical and pharmaceutical approaches. In the present paper a novel polysaccharidic matrix based on calcium alginate (Ca(II)-Alg) hydrogel and dextran methacrylate derivative (Dex-MA), showing potential applicability in the field of pharmaceutics is described. The semi-interpenetrating polymer system (semi-IPN) obtained by a dispersion of Dex-MA chains into a Ca(II) hydrogel leads to a hydrogel with theological properties quite different from those of Ca(II)-Alg, allowing to inject the semi-IPN easily through an hypodermic needle. The UV curing of the semi-IPN, by cross-linking of the methacrylate moieties, leads to an IPN strong hydrogel that can be used for a modulated delivery of bioactive molecules. In the present paper, theological and mechanical behaviors of the semi-IPN and of the IPN are discussed. The release of model molecules, including a protein, are also presented to show the suitability of the novel system as a drug delivery system

IBTK Differently Modulates Gene Expression and RNA Splicing in HeLa and K562 Cells

The IBTK gene encodes the major protein isoform IBTKα that was recently characterized as substrate receptor of Cul3-dependent E3 ligase, regulating ubiquitination coupled to proteasomal degradation of Pdcd4, an inhibitor of translation. Due to the presence of Ankyrin-BTB-RCC1 domains that mediate several protein-protein interactions, IBTKα could exert expanded regulatory roles, including interaction with transcription regulators. To verify the effects of IBTKα on gene expression, we analyzed HeLa and K562 cell transcriptomes by RNA-Sequencing before and after IBTK knock-down by shRNA transduction. In HeLa cells, 1285 (2.03%) of 63,128 mapped transcripts were differentially expressed in IBTK-shRNA-transduced cells, as compared to cells treated with control-shRNA, with 587 upregulated (45.7%) and 698 downregulated (54.3%) RNAs. In K562 cells, 1959 (3.1%) of 63128 mapped RNAs were differentially expressed in IBTK-shRNA-transduced cells, including 1053 upregulated (53.7%) and 906 downregulated (46.3%). Only 137 transcripts (0.22%) were commonly deregulated by IBTK silencing in both HeLa and K562 cells, indicating that most IBTKα effects on gene expression are cell type-specific. Based on gene ontology classification, the genes responsive to IBTK are involved in different biological processes, including in particular chromatin and nucleosomal organization, gene expression regulation, and cellular traffic and migration. In addition, IBTK RNA interference affected RNA maturation in both cell lines, as shown by the evidence of alternative 3′- and 5′-splicing, mutually exclusive exons, retained introns, and skipped exons. Altogether, these results indicate that IBTK differently modulates gene expression and RNA splicing in HeLa and K562 cells, demonstrating a novel biological role of this protein

Eukaryotic Initiation Factor 4H Is under Transcriptional Control of p65/NF-κB

<div><p>Protein synthesis is mainly regulated at the initiation step, allowing the fast, reversible and spatial control of gene expression. Initiation of protein synthesis requires at least 13 translation initiation factors to assemble the 80S ribosomal initiation complex. Loss of translation control may result in cell malignant transformation. Here, we asked whether translational initiation factors could be regulated by NF-κB transcription factor, a major regulator of genes involved in cell proliferation, survival, and inflammatory response. We show that the p65 subunit of NF-κB activates the transcription of eIF4H gene, which is the regulatory subunit of eIF4A, the most relevant RNA helicase in translation initiation. The p65-dependent transcriptional activation of eIF4H increased the eIF4H protein content augmenting the rate of global protein synthesis. In this context, our results provide novel insights into protein synthesis regulation in response to NF-κB activation signalling, suggesting a transcription-translation coupled mechanism of control.</p></div

TNF-α induces the recruitment of p65 to eIF4H promoter.

<p>(A) HeLa cells (5×10⁶) were transfected with siRNA control or siRNA p65 (200 pmol). Forty-eight hours post-transfection, cells were 45 min-treated with TNF-α (20 ng/mL), or left untreated. Total RNA was extracted and analysed by qRT-PCR to measure the expression of eIF4H and eIF2S3. Values (mean ± SD, n = 3) are shown. Statistically significant differences between the samples are shown according to Student's <i>t</i>-test (p≤0.01). (B) HeLa cells (3×10⁷) were treated with TNF-α (20 ng/mL) for the indicated time, or left untreated. Chromatin was immunoprecipitated with anti-p65, anti-p50, anti-RelB, anti-c-Rel or IgG, and ChIP eluates were analysed by qRT-PCR.</p

p65-dependent transcriptional activation of eIF4H.

<p>(A) HeLa cells (5×10⁶) were transfected with pRc/CMV-p65 or pRc/CMV-empty vector (5 µg). Forty-eight hours post-transfection, total RNA was extracted and analysed by qRT-PCR to evaluate the expression of the indicated eIF genes. Values (mean ± SD, n = 5) are shown. The asterisk indicates a statistically significant difference between pRc/CMV-p65 and empty vector according to the Student's <i>t</i>-test (<i>p</i>≤0.01). (B) HeLa cells (5×10⁶) were transfected with siRNA control or siRNA p65 (200 pmol). Forty-eight hours post-transfection, total RNA was extracted and analysed by qRT-PCR for the expression of the indicated eIF genes. Values (mean ± SD, n = 5) are shown. The asterisk indicates a statistically significant difference between siRNA p65 and siRNA control according to the Student's <i>t</i>-test (<i>p</i> ≤0.01). (C) Wild type and p65^−/− MEFs (3×10⁵) were lysed, and total RNA was analysed by qRT-PCR for the expression of eIF4H gene. (D) Total cell extracts (20µg) of wild type and p65^−/− MEFs (3×10⁵) were separated by 12% SDS-PAGE and analysed by western blotting using anti-eIF4H, or anti-γ-Tubulin antibodies. Densitometry values (D) of the bands were expressed as fold increase above the wild type taken as 1. (E) Nuclear extracts of wild type and p65^−/− MEFs (5×10⁶ cells) were analysed for the binding activity of the indicated NF-κB subunits to the NF-κB double-stranded oligonucleotide, as measured by ELISA EMSA using the NF-κB Transcription Factor ELISA assay kit (Cayman). (F) Total RNA from tumour cell lines (MDA-MB-231, MCF-7, SH-SY5Y, U251, D54, MC3, DeFew) (3×10⁵ cells) was analysed by qRT-PCR for the expression of eIF4H gene. (G) Whole protein cell extracts (20µg) of the indicated tumour cell lines were separated by 12% SDS–PAGE and analysed by western blotting using anti-eIF4H, or anti-γ-Tubulin antibodies. Densitometry values (D) of the bands were expressed as fold increase above the MDA-MB-231 cells taken as 1. (H) Nuclear extracts of the indicated tumor cell lines (5×10⁶ cells) were analysed for the p65 binding to the NF-κB double-stranded oligonucleotide, using the NF-κB Transcription Factor ELISA assay kit (Cayman).</p

Bioinformatics-based prediction of NF-κB sites in eIFH promoters.

<p>Jaspar- and TFSEARCH-based computational analysis predicted putative NF-κB enhancers in the promoter regions of core eukaryotic translation initiation factors.</p

p65-dependent modulation of EIF4H protein expression.

<p>(A) HeLa cells (5×10⁶) were transfected with pRc/CMV-3HA-p65, pRc/CMV-3HA-IκB-α, or pRc/CMV empty vector (5µg), and 48h later whole cell extracts were recovered. Protein extracts (20µg) were separated by 12% SDS–PAGE and analysed by western blotting using anti-HA, anti-eIF4H, or anti-γ-Tubulin antibodies. Densitometry values (D) of the bands were expressed as fold increase above the empty vector, taken as 1. (B) HeLa cells (5×10⁶) were transfected with siRNA control, or siRNA p65 (200 pmol), and forty-eight hours post-transfection whole cell extracts were performed. Protein samples (20µg) were separated by 12% SDS–PAGE, and analysed by western blotting using anti-eIF4H, anti-p65, or anti-γ-Tubulin antibodies. Densitometry values (D) of the bands were expressed as fold increase above siRNA control, taken as 1. (C) HeLa cells (5×10⁶) were 45 min-stimulated with TNF-α (20 ng/mL), or left untreated, washed twice with DMEM, and lysed to perform total extracts and nuclear extracts. Upper panel, total cell extracts (20µg) were separated by 12% SDS–PAGE and analysed by western blotting using anti-eIF4H or anti-γ-Tubulin antibodies. Densitometry values (D) of the bands were expressed as fold increase above un-stimulated cells, taken as 1. Lower panel, nuclear extracts were analysed for the p65 binding to the NF-κB double-stranded oligonucleotide by ELISA EMSA.</p