Biomedical subjects

Marta Muzio

Publications and source records attributed to Marta Muzio.

7 recordsLinked to original sources

PubMed2004

The death domain protein p84N5, but not the short isoform p84N5s, is cell cycle-regulated and shuttles between the nucleus and the cytoplasm.

P84N5 is a death domain containing protein that interacts with the tumor suppressor retinoblastoma protein and induces apoptosis. We cloned and characterized two novel alternatively spliced versions of p84N5. The p84N5 short isoform (p84N5s) lacks the death domain and does not induce apoptosis. We showed that p84N5, but not p84N5s, is cell cycle regulated. We found that p84N5-GFP chimera can rapidly shuttle between the nucleus and the cytoplasm. Taken together, these observations suggest that p84N5 may transmit signals from the nucleus to cytoplasmic effectors.

Base Sequence↗

PubMed2004

Intestinal inflammation in mice deficient in Tir8, an inhibitory member of the IL-1 receptor family.

TIR8, also known as single Ig IL-1-related receptor, is a member of the IL-1 receptor/Toll-like receptor (TLR) superfamily, which acts as an intracellular decoy for components of the signaling pathway. Here we report that Tir8 has a unique pattern of expression, which includes mucosal tissues and dendritic cells (DC). Tir8-deficient DC showed increased cytokine production in response to TLR agonists (lipopolysaccharide, CpG oligodeoxynucleotides). Tir8-deficient mice had normal susceptibility to systemic lipopolysaccharide toxicity and to i.p. or s.c. inflammation. However, Tir8-deficient mice were more susceptible to intestinal inflammation. Thus, TIR8 represents a negative pathway of regulation of the IL-1 receptor/TLR system, expressed in epithelial cells and DC, crucial for tuning inflammation in the gastrointestinal tract.

Animals↗

PubMed2004

TNF signaling: key protocols.

Tumor necrosis factor (TNF) is a pleiotropic cytokine that signals inflammation as well as cell death. We focus herein on the inflammatory pathway, giving particular emphasis to the in vitro methods used to study intracellular signaling mediators. The signal transduction cascade that TNF triggers after binding to the TNF receptors (TNFRs), flows throughout a series of protein-protein interactions as well as kinase activations, and finally leads to the translocation of distinct transcription factors within the nucleus, eventually inducing the transcription of specific inflammatory genes. In this chapter, we describe the analysis of the TNF receptor signaling complex by immunoprecipitation (IP), the activation of different MAP kinases by Western blot, the analysis of transcription factor activation by either electrophoretic mobility-shift assay (EMSA) or reporter assay, and the analysis of TNF-induced genes by chromatin IP (ChIP).

Biochemistry↗

PubMed2003

Acetaminophen down-regulates interleukin-1beta-induced nuclear factor-kappaB nuclear translocation in a human astrocytic cell line.

In previous studies performed to elucidate acetaminophen mechanism of action, we demonstrated that acetaminophen inhibits prostaglandin E2 production by interleukin (IL)-1beta-stimulated T98G human astrocytic cells, without affecting cyclooxygenase-2 enzymatic activity. As this result suggests an effect at transcriptional level, we examined whether the drug interferes with the activation of nuclear factor (NF)-kappaB and STAT3 transcription factors and with SAPK signal transducing factor. Western blot analysis of IkappaBalpha protein in the cytoplasm of IL-1beta-stimulated T98G cells and electrophoretic mobility shift assay (EMSA) on corresponding nuclear extracts indicate that acetaminophen (10-1000 microM) dose-dependently inhibits both IkappaBalpha degradation and NF-kappaB nuclear translocation. In the same cell type neither IL-1beta-dependent SAPK activation nor IL-6-induced STAT3 phosphorylation is affected by the drug. These data indicate that therapeutic concentrations of acetaminophen induce an inhibition of IL-1beta-dependent NF-kappaB nuclear translocation. The selectivity of this effect suggests the existence of an acetaminophen specific activity at transcriptional level that may be one of the mechanisms through which the drug exerts its pharmacological effects.

Acetaminophen↗

PubMed2003

Monitoring of apoptosis of HL60 cells by Fourier-transform infrared spectroscopy.

Fourier-transform infrared (FTIR) spectroscopy is a vibrational technique that gives information on the chemical composition of a sample, providing a "molecular fingerprint" of it. It is a powerful approach to study intact cells. The aim of the present study was to analyse and quantify apoptotic cells by using a FTIR approach based on attenuated total reflection (ATR). We incubated human HL60 leukaemic cells with camptothecin, a cytotoxic drug, and monitored apoptosis induction over a period of time. Several ATR-FTIR spectral changes occurred during the apoptotic process. In particular, we observed that the apoptotic index was inversely correlated with the spectral area in the region 1200-900 cm(-1), assigned to the absorption of nucleic acids. We therefore propose that ATR-FTIR spectral features may be used as a diagnostic marker of apoptotic cells.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Stimulation of toll-like receptor 4 expression in human mononuclear phagocytes by interferon-gamma: a molecular basis for priming and synergism with bacterial lipopolysaccharide.

In human monocytes and macrophages, interferon-gamma (IFNgamma) augmented mRNA and surface expression of toll-like receptor 4 (TLR4), a crucial component of the signaling receptor complex for bacterial lipopolysaccharide (LPS). Expression of the accessory component MD-2 and of the adapter protein MyD88 was also increased. LPS increased TLR4 mRNA levels, but concomitantly decreased its surface expression. IFNgamma counteracted the LPS-induced downregulation of TLR4. IFNgamma-primed monocytes showed increased responsiveness to LPS in terms of phosphorylation of the interleukin-1 receptor-associated kinase (IRAK; immediately downstream of the MyD88 adapter protein), NF-kB DNA binding activity, and, accordingly, of cytokine (tumor necrosis factor alpha [TNFalpha] and interleukin-12 [IL-12]) production. These results suggest that enhanced TLR4 expression underlies the long-known priming by IFNgamma of mononuclear phagocytes for pathogen recognition and killing as well as its synergism with LPS in macrophage activation.

Antigens, Surface↗

PubMedDate not supplied

Unique pattern of expression and inhibition of IL-1 signaling by the IL-1 receptor family member TIR8/SIGIRR.

TIR8, also known as single Ig IL-1R-related molecule (SIGIRR), is a member of the IL-1 receptor family. The present study was designed to investigate the expression and function of TIR8. TIR8 was mainly expressed in mouse and human epithelial tissues such as kidney, lung and gut. Resting and activated T and B lymphocytes and monocytes-macrophages expressed little or no TIR8, with the exception of the mouse GG2EE macrophage line. In the kidney, the organ with highest mRNA levels, TIR8 expression was confined to epithelial cells and, in situ, to tubular epithelium. A variety of signals failed to regulate TIR8 expression, but LPS reduced TIR8 mRNA transcripts. An NF-kB driven reporter system was used to investigate the function of TIR8. TIR8 did not activate NF-kB expression alone or in concert with IL-1R1. In contrast, TIR8 inhibited signaling from the IL-1R complex. Inhibition required the intracellular portion of TIR8 but the extracellular domain was dispensable for blocking activity. Thus, TIR8 is a unique member of the IL-1R family, with a distinct pattern of epithelial expression, including the kidney and mucosae, and an inhibitory function on IL-1 signaling.

Animals↗