Genotoxicity and gene expression modulation of silver and titanium dioxide nanoparticles in mice.

Recently, we showed that silver nanoparticles (AgNPs) caused apoptosis, necrosis and DNA strand breaks in different cell models in vitro. These findings warranted analyses of their relevance in vivo. We investigated the genotoxic potential and gene expression profiles of silver particles of nano- (Ag20, 20 nm) and submicron- (Ag200, 200 nm) size and titanium dioxide nanoparticles (TiO2-NPs, 21 nm) in selected tissues from exposed male mice including the gonades.

Preconceptional paternal glycidamide exposure affects embryonic gene expression: single embryo gene expression study following in vitro fertilization.

Recognition of early determinants of disease onset has sparked an interest in paternally transmitted factors and their impact on the developing embryo. Acrylamide (AA), a widely distributed xenobiotic compound, is converted to its active metabolite glycidamide (GA) by the CYP2E1 enzyme. Based on its capacity to induce dominant lethal mutations, we hypothesized that paternal GA exposure would have a negative impact on embryonic genome activation, via GA-DNA and protamine adducts persisting in the fertilizing sperm.

SNX1 and SNX2 mediate retrograde transport of Shiga toxin.

The bacterial toxin Shiga toxin (Stx) is transported retrogradely from early endosomes to the Golgi apparatus on its way to the endoplasmic reticulum (ER) and the cytosol. In this study we explored the functions of the two phosphoinositide binding proteins Sorting nexin 1 (SNX1) and Sorting nexin 2 (SNX2) in endosomal sorting of the toxin. When Vero cells were depleted of either SNX1 or SNX2 by small interfering RNA (siRNA), Stx transport to the trans-Golgi network (TGN) was impaired by > or = 40%, whereas combined depletion of SNX1 and SNX2 gave a total inhibition of approximately 80%.

Transport of ricin from endosomes to the Golgi apparatus is regulated by Rab6A and Rab6A'.

Ricin is transported from early endosomes and/or the recycling compartment to the trans-Golgi network (TGN) and subsequently to the endoplasmic recticulum (ER) before it enters the cytosol and intoxicates cells. We have investigated the role of the Rab6 isoforms in retrograde transport of ricin using both oligo- and vector-based RNAi assays. Ricin transport to the TGN was inhibited by the depletion of Rab6A when the Rab6A messenger RNA (mRNA) levels were reduced by more than 40% and less than 75%.

Shiga toxin regulates its entry in a Syk-dependent manner.

Shiga toxin (Stx) is composed of an A-moiety that inhibits protein synthesis after translocation into the cytosol, and a B-moiety that binds to Gb3 at the cell surface and mediates endocytosis of the toxin. After endocytosis, Stx is transported retrogradely to the endoplasmic reticulum, and then the A-fragment enters the cytosol. In this study, we have investigated whether toxin-induced signaling is involved in its entry.

ERK2 prohibits apoptosis-induced subcellular translocation of orphan nuclear receptor NGFI-B/TR3.

Transcription factor NGFI-B (neuronal growth factor-induced clone B), also called Nur77 or TR3, is an immediate early gene and an orphan member of the nuclear receptor family. The NGFI-B protein also has a function distinct from that of a transcription factor; it translocates to mitochondria to initiate apoptosis. Recently, it was demonstrated that NGFI-B interacts with Bcl-2 by inducing a conformational change in Bcl-2, converting it from protector to a killer.

High molecular weight DNA fragments are processed by caspase sensitive or caspase independent pathways in cultures of cerebellar granule neurons.

Many recent reports on internucleosomal DNA fragments have appeared, however, little is known about the mechanisms of the generation of their upstream high molecular weight (HMW) fragments. Caspases are a family of proteases with important functions in the execution of apoptotic cell death. The caspase-sensitivity of the formation of HMW fragments was therefore investigated using a specific caspase-3 inhibitor (Ac-DEVD-cmk) and a general caspase inhibitor (boc-D-fmk).

Nuclear receptor and apoptosis initiator NGFI-B is a substrate for kinase ERK2.

NGFI-B is an inducible orphan nuclear receptor that initiates apoptosis. Growth factors such as EGF activate the MAP kinase ERK, whose activity may determine if a cell survives or undergoes apoptosis. EGF stimulation of cells leads to phosphorylation of threonine in NGFI-B.