Comparative analysis of Trichinella spiralis and Trichinella nativa proteins by two-dimensional gel electrophoresis

Trichinella spiralis and Trichinella nativa are both common wildlife parasites in Finland. However, they differ substantially in their resistance to below 0 degrees C temperatures in their natural hosts. T. nativa can live in frozen fox meat for years, whereas T. spiralis dies when frozen. In mouse muscle, the difference is not as evident; even T. nativa cannot maintain infectivity when kept at -20 degrees C for 1 week. Crude larval protein extracts of these two parasite species were analyzed by two-dimensional gel electrophoresis (2DE). The protein patterns showed clear differences, but matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) peptide mass fingerprint followed by database searches failed to identify these proteins, suggesting that they may still be uncharacterized. The patterns compared after freezing treatment at -20 degrees C revealed changes in the intensity of some protein spots. The antigenic differences of the species were analyzed with two-dimensional Western blots, which showed T. spiralis-specific proteins.

Loss of p27Kip1 from cyclin E/cyclin-dependent kinase (CDK) 2 but not from cyclin D1/CDK4 complexes in cells transformed by polyamine biosynthetic enzymes

Cancer cells are known to display up-regulation of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC), the key enzymes in the biosynthesis of polyamines that are essential for cellular proliferation. We have shown previously that overexpression of ODC or AdoMetDC alone can induce tumorigenic transformation of rodent fibroblasts. Because the subversion of normal cell cycle control is thought to be a crucial event in cancer development, we examined ODC- and AdoMetDC-transformed fibroblasts for alterations in the cell cycle components. The level of cyclin D1 and cyclin D1-dependent kinase and total cyclin-dependent kinase (CDK) 4 activities were elevated in the ODC transformants and particularly in the AdoMetDC transformants. Cyclin E content was not elevated, but a moderate increase in cyclin E-dependent kinase activity was seen in both cells. Total CDK2 activity was increased only in the ODC-transformed cells. The amount of the p27Kip1 CDK inhibitor was greatly decreased in both transformants. Nevertheless, p27Kip1 was present in the active cyclin D1/CDK4 complexes in the cells but absent from the cyclin E/CDK2 complexes. Restoration of p27Kip1 expression in the ODC- and AdoMetDC-transformed cells by transfection resulted in growth inhibition, but not in morphological reversion. An elevation in the level of hyperphosphorylated retinoblastoma protein was observed mainly in the ODC-transformed cells. These results suggest that the expression of ODC or AdoMetDC may affect cell cycle regulation in many ways. However, the largest common effect, which is therefore potentially relevant to some aspects of transformation, appears to be the constitutive down-regulation of p27Kip1 and its loss from the cyclin/CDK2 complexes.