Curcumin stimulates glucose uptake through AMPK‐p38 MAPK pathways in L6 myotube cells

Curcumin has been shown to exert a variety of beneficial human health effects. However, mechanisms by which curcumin acts are poorly understood. In this study, we report that curcumin activated AMP‐activated protein kinase (AMPK) and increased glucose uptake in rat L6 myotubes. In addition, curcumin activated the mitogen‐activated protein kinase kinase (MEK)3/6‐p38 mitogen‐activated protein kinase (MAPK) signaling pathways in the downstream of the AMPK cascade. Moreover, inhibition of either AMPK or p38 MAPK resulted in blockage of curcumin‐induced glucose uptake. Furthermore, the administration of curcumin to mice increased AMPK phosphorylation in the skeletal muscles. Taken together, these results indicate that the beneficial health effect of curcumin can be explained by its ability to activate AMPK‐p38 MAPK pathways in skeletal muscles. J. Cell. Physiol. 223:771–778, 2010. © 2010 Wiley‐Liss, Inc.     

TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli

This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO₂) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO₂ photocatalysis on E. coli survival was monitored by counting on agar plate and by assessing lipid peroxidation and performing proteomic analysis. We observed through malondialdehyde quantification that lipid peroxidation occurred during the photocatalytic process, and the addition of superoxide dismutase, which acts as a scavenger of the superoxide anion radical (O₂·⁻), inhibited this effect by half, showing us that O₂·⁻ radicals participate in the photocatalytic antimicrobial effect. Qualitative analysis using two-dimensional electrophoresis allowed selection of proteins for which spot modifications were observed during the applied treatments. Two-dimensional electrophoresis highlighted that among the selected protein spots, 7 and 19 spots had already disappeared in the dark in the presence of 0.1 g/liter and 0.4 g/liter TiO₂, respectively, which is accounted for by the cytotoxic effect of TiO₂. Exposure to 30 min of UV-A radiation in the presence of 0.1 g/liter and 0.4 g/liter TiO₂ increased the numbers of missing spots to 14 and 22, respectively. The proteins affected by photocatalytic oxidation were strongly heterogeneous in terms of location and functional category. We identified several porins, proteins implicated in stress response, in transport, and in bacterial metabolism. This study reveals the simultaneous effects of O₂·⁻ on lipid peroxidation and on the proteome during photocatalytic treatment and therefore contributes to a better understanding of molecular mechanisms in antibacterial photocatalytic treatment.     

STIM1 Positively Regulates the Ca2+ Release Activity of the Inositol 1,4,5-Trisphosphate Receptor in Bovine Aortic Endothelial Cells

The endothelium is actively involved in many functions of the cardiovascular system, such as the modulation of arterial pressure and the maintenance of blood flow. These functions require a great versatility of the intracellular Ca²⁺ signaling that resides in the fact that different signals can be encoded by varying the frequency and the amplitude of the Ca²⁺ response. Cells use both extracellular and intracellular Ca²⁺ pools to modulate the intracellular Ca²⁺ concentration. In non-excitable cells, the inositol 1,4,5-trisphosphate receptor (IP₃R), located on the endoplasmic reticulum (ER), is responsible for the release of Ca²⁺ from the intracellular store. The proteins STIM1 and STIM2 are also located on the ER and they are involved in the activation of a store-operated Ca²⁺ entry (SOCE). Due to their Ca²⁺ sensor property and their close proximity with IP₃Rs on the ER, STIMs could modulate the activity of IP₃R. In this study, we showed that STIM1 and STIM2 are expressed in bovine aortic endothelial cells and they both interact with IP₃R. While STIM2 appears to play a minor role, STIM1 plays an important role in the regulation of agonist-induced Ca²⁺ mobilization in BAECs by a positive effect on both the SOCE and the IP₃R-dependent Ca²⁺ release.     

Generation of Sprn-regulated reporter mice reveals gonadic spatial expression of the prion-like protein Shadoo in mice

The protein Shadoo (Sho) is a paralogue of prion protein, and encoded by the gene Sprn. Like prion protein it is primarily expressed in central nervous system, and has been shown to have a similar expression pattern in certain regions of the brain. We have generated reporter mice carrying a transgene encompassing the Sprn promoter, exon 1, intron 1 and the 5′-end of exon 2 driving expression of either the LacZ or GFP reporter gene to study the expression profile of Shadoo in mice. Expression of the reporter genes was analysed in brains of these transgenic mice and was shown to mimic that of the endogenous gene expression, previously described by Watts et al. [1]. Consequently, the Sprn-LacZ mice were used to study the spatial expression of Sho in other tissues of the adult mouse. Several tissues were collected and stained for β-gal activity, including the thymus, heart, lung, liver, kidney, spleen, intestine, muscle, and gonads. From this array of tissues, the transgene was consistently expressed only in specific cell types of the testicle and ovary, suggesting a role for Shadoo in fertility and reproduction. These mice may serve as a useful tool in deciphering the regulation of the prion-like gene Sprn and thus, indirectly, of the Shadoo protein.     

Genomic Analysis of Natural Selection and Phenotypic Variation in High-Altitude Mongolians

Deedu (DU) Mongolians, who migrated from the Mongolian steppes to the Qinghai-Tibetan Plateau approximately 500 years ago, are challenged by environmental conditions similar to native Tibetan highlanders. Identification of adaptive genetic factors in this population could provide insight into coordinated physiological responses to this environment. Here we examine genomic and phenotypic variation in this unique population and present the first complete analysis of a Mongolian whole-genome sequence. High-density SNP array data demonstrate that DU Mongolians share genetic ancestry with other Mongolian as well as Tibetan populations, specifically in genomic regions related with adaptation to high altitude. Several selection candidate genes identified in DU Mongolians are shared with other Asian groups (e.g., EDAR), neighboring Tibetan populations (including high-altitude candidates EPAS1, PKLR, and CYP2E1), as well as genes previously hypothesized to be associated with metabolic adaptation (e.g., PPARG). Hemoglobin concentration, a trait associated with high-altitude adaptation in Tibetans, is at an intermediate level in DU Mongolians compared to Tibetans and Han Chinese at comparable altitude. Whole-genome sequence from a DU Mongolian (Tianjiao1) shows that about 2% of the genomic variants, including more than 300 protein-coding changes, are specific to this individual. Our analyses of DU Mongolians and the first Mongolian genome provide valuable insight into genetic adaptation to extreme environments.     

The bc(1) complex of the iron-grown acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans functions in the reverse but not in the forward direction. Is there a second bc(1) complex?

Acidithiobacillus ferrooxidans is an acidophilic chemolithotrophic bacterium that can grow in the presence of either a weak reductant, Fe(2+), or reducing sulfur compounds that provide more energy for growth than Fe(2+). Here we first review the latest findings about the uphill electron transfer pathway established in iron-grown A. ferrooxidans, which has been found to involve a bc(1) complex. We then provide evidence that this bc(1) complex cannot function in the forward direction (exergonic reaction), even with an appropriate substrate. A search for the sequence of the three redox subunits of the A. ferrooxidans bc(1) complex (strain ATCC 19859) in the complete genome sequence of the A. ferrooxidans ATCC 23270 strain showed the existence of two different bc(1) complexes in A. ferrooxidans. Cytochrome b and Rieske protein sequence comparisons allowed us to point out some sequence particularities of these proteins in A. ferrooxidans. Lastly, we discuss the possible reasons for the existence of two different "classical" bc(1) complexes and put forward some suggestions as to what role these putative complexes may play in this acidophilic chemolithotrophic bacterium.     

Replication of Norovirus in cell culture reveals a tropism for dendritic cells and macrophages

Noroviruses are understudied because these important enteric pathogens have not been cultured to date. We found that the norovirus murine norovirus 1 (MNV-1) infects macrophage-like cells in vivo and replicates in cultured primary dendritic cells and macrophages. MNV-1 growth was inhibited by the interferon-αβ receptor and STAT-1, and was associated with extensive rearrangements of intracellular membranes. An amino acid substitution in the capsid protein of serially passaged MNV-1 was associated with virulence attenuation in vivo. This is the first report of replication of a norovirus in cell culture. The capacity of MNV-1 to replicate in a STAT-1-regulated fashion and the unexpected tropism of a norovirus for cells of the hematopoietic lineage provide important insights into norovirus biology.