The N-Terminal, Polybasic Region Is Critical for Prion Protein Neuroprotective Activity

Several lines of evidence suggest that the normal form of the prion protein, PrPC, exerts a neuroprotective activity against cellular stress or toxicity. One of the clearest examples of such activity is the ability of wild-type PrPC to suppress the spontaneous neurodegenerative phenotype of transgenic mice expressing a deleted form of PrP (Δ32–134, called F35). To define domains of PrP involved in its neuroprotective activity, we have analyzed the ability of several deletion mutants of PrP (Δ23–31, Δ23–111, and Δ23–134) to rescue the phenotype of Tg(F35) mice. Surprisingly, all of these mutants displayed greatly diminished rescue activity, although Δ23–31 PrP partially suppressed neuronal loss when expressed at very high levels. Our results pinpoint the N-terminal, polybasic domain as a critical determinant of PrPC neuroprotective activity, and suggest that identification of molecules interacting with this region will provide important clues regarding the normal function of the protein. Small molecule ligands targeting this region may also represent useful therapeutic agents for treatment of prion diseases

Remarkable Reduction of MAP2 in the Brains of Scrapie-Infected Rodents and Human Prion Disease Possibly Correlated with the Increase of Calpain

Microtubule-associated protein 2 (MAP2) belongs to the family of heat stable MAPs, which takes part in neuronal morphogenesis, maintenance of cellular architecture and internal organization, cell division and cellular processes. To obtain insight into the possible alteration and the role of MAP2 in transmissible spongiform encephalopathies (TSEs), the MAP2 levels in the brain tissues of agent 263K-infected hamsters and human prion diseases were evaluated. Western blots and IHC revealed that at the terminal stages of the diseases, MAP2 levels in the brain tissues of scrapie infected hamsters, a patient with genetic Creutzfeldt-Jakob disease (G114V gCJD) and a patient with fatal familial insomnia (FFI) were almost undetectable. The decline of MAP2 was closely related with prolonged incubation time. Exposure of SK-N-SH neuroblastoma cell line to cytotoxic PrP106-126 peptide significantly down-regulated the cellular MAP2 level and remarkably disrupted the microtubule structure, but did not alter the level of tubulin. Moreover, the levels of calpain, which mediated the degradation of a broad of cytoskeletal proteins, were significantly increased in both PrP106-126 treated SK-N-SH cells and brain tissues of 263K prion-infected hamsters. Our data indicate that the decline of MAP2 is a common phenomenon in TSEs, which seems to occur at an early stage of incubation period. Markedly increased calpain level might contribute to the reduction of MAP2

Relation between nuclear DNA content and rate of cell growth during interphase in four species of Angiospermae

Among four species of Angiospermae with known nuclear DNA content (Cucurbita pepo - 2.6 pg, Helianthus annuus - 12.0 pg, Vicia faba — 38.0 pg, and Tulipa kaufmanniana - 93.7 pg) the cell growth in the intermitotic period of the cell cycle has been observed to be the fastest in Vicia faba, slower in Helianthus annuus and the slowest in Cucurbita pepo and Tulipa kaufmanniana

Resistance to Phytophthora infestans in diploid and tetraploid potato families. 1. Resistance in detached leaflets

Potato families, segregating for resistance to Phytophthora infestans, were tested repeatedly to evaluate the distribution of resistance to P. infestans, the repeatability of testing results and correlation between resistance and some other characters. Four diploid and four tetraploid families were evaluated together with their parents and with potato cultivars used as standard. For all inoculations a virulent fungus isolate MP 245 was used. Leaflets were collected from plants growing in the field (summer tests) or in a glasshouse (autumn and spring tests). Segregation of major genes determining resistance was detectable in most families. In families originating from mating a resistant parent with a susceptible partner some progeny genotypes with resistance level of the resistant parent could be identified. In families originating from two parents showing only some resistance, a transgression of resistance could be found in the progeny. The expression of resistance depended on testing conditions. Some genotypes were consistently superior or inferior in resistance under all testing conditions, but often repeated evaluations of genotypes did not provide consistent results and significant interactions genotypes x tests were detectable

Efekt antynowotworowy inhibitora szlaku syntezy cholesterolu – lowastatyny i terapii fotodynamicznej w raku jelita grubego in vitro

Photodynamic therapy (PDT) is a promising treatment method for non-oncological and oncological diseases. PDT requires the use of photosensitizer, light, and cell oxygen. A selective, cytotoxic effects can be achieved in cancer cells, thanks to formation of radical oxygen species (ROS). Recent data indicate, that PDT with aminolevulinic acid (ALA) is successful in treatment of colorectal cancer. However, anti-cancer effects PDT in vivo, can vary in PDT in vitro, due to low level of oxygenation of tumor cells. Experimental research confirms the role of cholesterol in oncogenesis and indicates, that in colorectal cancer the cholesterol synthesis is disrupted; among others lovastatin belong to inhibitors 3-hydroxy-3-methyl-glutharyl-coenzyme A (HMG-CoA) enzyme of cholesterol synthesis pathway. Anti-tumor potential of statins: antiproliferative and pro-apoptotic, were demonstrated in various tumors in vitro and in vivo. Colorectal cancer, which often has genes mutations that are related to programmed death cells, shows resistance to chemotherapy. The objective of the research was to investigate the effect of antiproliferative and cytotoxic lovastatin and ALA-PDT (in low dose) working separately and in combination method (lovastatin and PDT) − for apoptosis induction, in metastatic colon cell line SW620. Our finding showed, that lovastatin inhibits the growth of cancer cells, depending on the dose and incubation time. ALA-PDT in low dose works on cell cytotoxic, yet do not initiate apoptosis. Whereas, preincubation of cells with lovastatin (IC50) increases the cytotoxic effect after PDT and induces apoptosis in cancer cells SW620, as demonstrated using an assay of Annexin V for flow cytometry. Our research demonstrates for the first time, the effectiveness of ALA-PDT connection with an inhibitor of cholesterol synthesis pathway – lovastatin, in increasing the cytotoxicity and induction of apoptosis in colon cancer cells, that are resistant to chemotherapy.Terapia fotodynamiczna (ang. photodynamic therapy, PDT) jest obiecującą metodą w leczeniu nowotworowych i nienowotworowych schorzeń. Działanie PDT wymaga użycia fotouczulacza, światła i tlenu komórkowego, dla uzyskania wybiórczego cytotoksycznego efektu w komórkach patologicznych. Efekt ten jest wynikiem powstania wolnych rodników (ROS). Badania pokazują, że PDT z kwasem aminolewulinowym (ALA) jest skuteczna w leczeniu raka jelita grubego. Jednak efekty PDT in vivo, ze względu na niski poziom oksygenacji guza, mogą odbiegać od działania PDT in vitro. Dane eksperymentalne potwierdzają rolę cholesterolu w procesie onkogenezy i wskazują na zaburzony szlak syntezy cholesterolu, m.in. w raku jelita grubego. Statyny, np. lowastatyna, należą do inhibitorów 3-hydroksy-3-metylo-glutarylo-koenzymu A (HMG-CoA) − enzymu szlaku syntezy cholesterolu. Potencjał antynowotworowy statyn, antyproliferacyjny i proapoptotyczny, wykazano w nowotworach in vitro i in vivo. Rak jelita grubego, cechujący się mutacjami genów związanych z apoptozą, wykazuje oporność na standardowe chemioterapeutyki. Celem pracy było zbadanie efektu antyproliferacyjnego i cytotoksycznego lowastatyny i ALA-PDT (w niskiej dawce) działających osobno, oraz w metodzie połączonej (lowastatyna i PDT) – na indukcję apoptozy w przerzutowej linii raka jelita grubego SW620. Wyniki pokazały, że lowastatyna hamuje wzrost komórek w związku zależnym od dawki i czasu inkubacji. ALA-PDT w niskiej dawce działa cytotoksycznie, ale nie inicjuje apoptozy. Natomiast preinkubacja komórek raka z lowastatyną (IC50) zwiększa efekt cytotoksyczny po PDT i indukuje apoptozę w komórkach, co wykazano w teście z aneksyną V na cytometrze przepływowym. Nasze wyniki po raz pierwszy demonstrują skuteczność metody łączonej: ALA-PDT i inhibitora syntezy szlaku cholesterolu – lowastatyny, w zwiększeniu cytotoksyczności i indukcji apoptozy w komórkach raka jelita grubego, opornego na chemioterapię

Resistance to Phytophthora infestans in diploid and tetraploid potato families. 2. Resistance in tubers

The tuber reaction to Phytophthora infestans was evaluated in individual genotypes of four diploid and four tetraploid potato families, their parents and standard cultivars. The genotypes were tested several times. Two testing methods were used, based on evaluation of tuber slices or whole tubers, respectively. All inoculations were done with MP 245, a fungus isolate with a broad virulence spectrum. If the reaction of tuber slices was evaluated, the distribution of genotypes in several families deviated considerably from a normal one. In some distributions more than one peak was detectable, indicating segregation of major genes. Genotypes transgressive in resistance were found in four families. If the reaction of whole tubers was evaluated, the distribution of genotypes did not deviate significantly from a normal one. Genotypes transgressive in resistance were found in one family. The tuber reaction to P. infestans depended to a large extent on testing conditions

Resistance to Phytophthora infestans in diploid and tetraploid potato families. 3. Correlations between characters

In four diploid and four tetraploid families correlations were evaluated between resistance to Phytophthora infestans of leaflets, tuber slices and whole tubers as well as correlations between three aspects of resistance and maturity or tuber shape regularity. A virulent P. infestans isolate was used for inoculations. Only in the family D4 a significant positive correlation was found between all the three aspects of resistance. Genotypes with susceptible leaflets and resistant tuber slices were not identified in any family. In some families genotypes with resistant whole tubers and susceptible tuber slices were found; the family D5 was found to have genotypes in which resistance of leaflets was associated with susceptibility of tuber slices. The resistance to P. infestans of leaflets or tuber slices tended to be negatively correlated with both early maturity and regularity of tuber shape

Electrochemical genosensing of the interaction between the potential chemotherapeutic agent, cis-bis(3-aminoflavone)dichloroplatinum(II) and DNA in comparison with cis-DDP

WOS: 000230718000009PubMed ID: 15967292The interaction of cis-diamminedichloroplatinum(II) (cis-DDP) and the potential novel chemotherapeutic agent, cis-bis(3-aminoflavone)dichloroplatinum(II) (cis-BAFDP) was studied electrochemically with calf thymus double-stranded DNA (dsDNA) by using differential pulse voltammetry (DPV) with disposable pencil graphite electrode (PGE) at the surface. These studies were prompted by beneficial biological properties of cis-BAFDP in comparison with cis-DDP, which were proven in vitro both in human normal and cancer cells and in vivo. The changes in the experimental parameters such as the concentration of cis-DDP and cis-BAFDP were studied by using DPV; in addition, the reproducibility of this genosensor and the detection limit for each compound were determined. After the interaction of cis-DDP with dsDNA, the DPV signal of guanine and adenine was found to be decreasing. In comparison with cis-DDP, a dramatic decrease at adenine signal was also obtained after the interaction of cis-BAFDP and dsDNA. Similar results were also found in solution phase after the latter compound interacts with poly[A]. The features of the proposed electrochemical method for the detection of cis-BAFDP with DNA in comparison with cis-DDP are discussed and compared with those methods previously reported for the other type of DNA-targeted agents in the literature. (c) 2005 Elsevier B.V. All rights reserved