We evaluated the nuclear actin accumulation as a new marker of cellular senescence, using human diploid fibroblast (HDF), chondrocyte primary cultures, Mv1Lu epithelial cells, and Huh7 cancer cells. Nuclear accumulation of globular actin (G-actin) and dephosphorylated cofilin was highly significant in the senescent HDF cells, accompanied with inhibition of LIM kinase (LIMK) -1 activity. When nuclear export of the actin was induced by 12-O-tetradecanoylphorbol-13-acetate, DNA synthesis of the senescent cells increased significantly, accompanied with changes of morphologic and biochemical profiles, such as increased RB protein phosphorylation and decreased expressions of p21 WAF1 , cytoplasmic pextracellular signal-regulated kinase 1/2, and caveolins 1 and 2. Significance of these findings was strengthened additionally by the fact that nuclear actin export of young HDF cells was inhibited by the treatment with leptomycin B and mutant cofilin transfection, whose LIMK-1 phosphorylation site was lost, and the old cell phenotypes were duplicated with nuclear actin accumulation, suggesting that nuclear actin accumulation was accompanied with G1 arrest during cellular senescence. The aforementioned changes were observed not only in the replicative senescence but also in the senescence induced by treatment of HDF cells, Mv1Lu, primary culture of human chondrocytes, or Huh7 cells with H-ras virus infection, hydroxyurea, deferoxamine, or H 2 O 2 . Nuclear actin accumulation was much more sensitive and an earlier event than the well-known, senescence-associated ␤-galactosidase activity.

No abstract

No abstract

No abstract

The development of a DNA microfluidic device with a high speed, low power, and low reagent volume is very critical for real-time genotyping and diagnosis in point-of-care applications. This paper reports a polymer-based thermal cycler for a handheld and battery-powered polymerase chain reaction (PCR) system using a polyimide (PI) film-based micro-fabricated heater module and polymer film microfluidic chambers of 10 μL, with a handheld and low power consumption, compared to state of the art. It took 21 min for 40 thermal cycling for DNA amplification and a maximum power consumption of 0.6 W. The microheater on PI film substrate fabricated and real-time quantification of deoxyribonucleic acid (DNA) using the heater in hand-held sizes experimentally shown here. The device would be applicable for on-site molecular diagnostics.