GATA elements control repression of cardiac troponin I promoter activity in skeletal muscle cells

Background  

We reported previously that the cardiac troponin I (cTnI) promoter drives cardiac-specific expression of reporter genes in cardiac muscle cells and in transgenic mice, and that disruption of GATA elements inactivates the cTnI promoter in cultured cardiomyocytes. We have now examined the role of cTnI promoter GATA elements in skeletal muscle cells.     

60-kDa heat shock protein of Chlamydia pneumoniae promotes a T helper type 1 immune response through IL-12/IL-23 production in monocyte-derived dendritic cells

Infection, in particular by Chlamydia pneumoniae (Cp), has been associated with atherosclerosis and coronary heart disease. Immune reactions to heat shock proteins (HSPs) have been advocated to link infection to atherosclerosis and its acute sequelae based on molecular mimicry with host HSPs. We have here evaluated the role played by recombinant Cp-HSP60 and Cp-HSP10 for their ability to induce maturation of human monocyte-derived dendritic cells (MDDC) and T cell polarization. Cp-HSP60, but not Cp-HSP10, induced a strong MDCC maturation, as assessed by the expression of co-stimulatory molecules and other markers. Secretion of regulatory cytokines and enhancement of antigen presenting ability of mature (m)MDDC toward a clear T helper (Th) 1 pattern were also induced by Cp-HSP60. An analysis of the IL-12 cytokine family demonstrated that Cp-HSP60-matured MDDC were able to express p35 and p40 mRNA subunits to form IL-12, and p19 and p40 subunits to form IL-23. Thus, preferential Th1 polarization of immune response induced by Cp-HSP60-matured MDDC appears to be due to the concomitant expression of IL-12 and IL-23. Our data suggest that Cp-HSP60-matured DC may contribute to T-cell mediated immunopathology of atherosclerosis via a chronic stimulation of Th1 immune responses.     

Facile, efficient approach to accomplish tunable chemistries and variable biodistributions for shell cross-linked nanoparticles

The in vivo behavior of shell cross-linked knedel-like (SCK) nanoparticles is shown to be tunable via a straightforward and versatile process that advances SCKs as attractive nanoscale carriers in the field of nanomedicine. Tuning of the pharmacokinetics was accomplished by grafting varied numbers of methoxy-terminated poly(ethylene glycol) (mPEG) chains to the amphiphilic block copolymer precursors, together with chelators for the radioactive tracer and therapeutic agent (64)Cu, followed by self-assembly into block copolymer micelles and chemical cross-linking throughout the shell regions. (64)Cu-radiolabeling was then performed to evaluate the SCKs in vivo by means of biodistribution experiments and positron emission tomography (PET). It was found that the blood retention of PEGylated SCKs could be tuned, depending on the mPEG grafting density and the nanoparticle surface properties. A semiquantitative model of the density of mPEG surface coverage as a function of in vivo behavior was applied to enhance the understanding of this system.     

<Emphasis Type="Italic">Crambe tataria</Emphasis>: actions for ex situ conservation

In vitro micropropagation by direct organogenesis and somatic embryogenesis via callus was developed for Crambe tataria (Brassicaceae). C. tataria is an endemic species of the Pontic-Pannonic region, but it is also present in Italy, where it is localized in Friuli on a characteristic grassland formation, called “magredi”. C. tataria is regarded as an endangered species. Leaf and root explants were subjected to plant regulator treatments, which invoked different morphogenic responses. Leaf explants produced more callus than root explants and a higher amount of callus was obtained with 1 mg l⁻¹ 2,4-D in combination with 2 mg l⁻¹ Kin. Somatic embryogenesis was obtained in calli maintained in a delayed subculture regime on media containing BAP in combination with NAA. Root explants cultured with BAP combined with NAA developed adventitious rosette shoots. Shoots rooted on half-strength MS media, and the number of roots per plantlet and their length were heavily dependent on sucrose content. The in vitro regenerated plantlets were acclimatized ex vitro and a mean of 50% of the plantlets survived and showed a true-to-type growth habit. This study describes the development of two in vitro micropropagation protocols, via direct organogenesis and via embryogenesis from callus, that are the basis for the application of in vitro tools for the establishment of basal collections with representative genetic diversity and for the long-term storage of plant genetic material.     

ArfGAP1 restricts Mycobacterium tuberculosis entry by controlling the actin cytoskeleton

The interaction of Mycobacterium tuberculosis (Mtb) with pulmonary epithelial cells is critical for early stages of bacillus colonization and during the progression of tuberculosis. Entry of Mtb into epithelial cells has been shown to depend on F‐actin polymerization, though the molecular mechanisms are still unclear. Here, we demonstrate that mycobacterial uptake into epithelial cells requires rearrangements of the actin cytoskeleton, which are regulated by ADP‐ribosylation factor 1 (Arf1) and phospholipase D1 (PLD1), and is dependent on the M3 muscarinic receptor (M₃R). We show that this pathway is controlled by Arf GTPase‐activating protein 1 (ArfGAP1), as its silencing has an impact on actin cytoskeleton reorganization leading to uncontrolled uptake and replication of Mtb. Furthermore, we provide evidence that this pathway is critical for mycobacterial entry, while the cellular infection with other pathogens, such as Shigella flexneri and Yersinia pseudotuberculosis, is not affected. Altogether, these results reveal how cortical actin plays the role of a barrier to prevent mycobacterial entry into epithelial cells and indicate a novel role for ArfGAP1 as a restriction factor of host–pathogen interactions.     

PRMT5 silencing selectively affects MTAP-deleted mesothelioma: In vitro evidence of a novel promising approach

Malignant mesothelioma (MM) is an aggressive asbestos-related cancer of the serous membranes. Despite intensive treatment regimens, MM is still a fatal disease, mainly due to the intrinsic resistance to current therapies and the lack of predictive markers and new valuable molecular targets. Protein arginine methyltransferase 5 (PRMT5) inhibition has recently emerged as a potential therapy against methylthioadenosine phosphorylase (MTAP)-deficient cancers, in which the accumulation of the substrate 5'-methylthioadenosine (MTA) inhibits PRMT5 activity, thus sensitizing the cells to further PRMT5 inhibition. Considering that the MTAP gene is frequently codeleted with the adjacent cyclin-dependent kinase inhibitor 2A (CDKN2A) locus in MM, we assessed whether PRMT5 could represent a therapeutic target also for this cancer type. We evaluated PRMT5 expression, the MTAP status and MTA content in normal mesothelial and MM cell lines. We found that both administration of exogenous MTA and stable PRMT5 knock-down, by short hairpin RNAs (shRNAs), selectively reduced the growth of MTAP-deleted MM cells. We also observed that PRMT5 knock-down in MTAP-deficient MM cells reduced the expression of E2F1 target genes involved in cell cycle progression and of factors implicated in epithelial-to-mesenchymal transition. Therefore, PRMT5 targeting could represent a promising new therapeutic strategy against MTAP-deleted MMs.