Moreover this cell line essentially grows estrogen independent and demonstrates pharmacological properties different to other BK-expressing cancer cells, which is possibly due to differential expression of ß-subunits. In contrast to MCF7 and T47D, MFM223 has a low ER and PR expression but a very strong AR expression. In adaptation and interference, exploring cofactors involved in prion replication and developing ultrasensitive prion detection and titration assays. Despite significant advances brought to the field with the development of PMCA, our understanding of the mechanism underlying prion replication remains limited. PMCA consists of repetitive cycles of sonication and incubation. The sonication is presumably responsible for breaking PrPSc particles into smaller fragments, whereas the incubation intervals between sonication cycles are believed to be required for the growth or elongation of PrPSc particles. Co-factors including RNA and polyanions were found to stimulate prion conversion in PMCA. On the other hand, sonication-induced degradation of RNA below a size optimal for amplification might limit the efficiency of amplification.
In PMCAb, the strains with the highest conformational stability showed the largest improvements in amplification efficiency. The current study introduced an experimental approach that relies on a series of kinetic experiments for testing the question of whether PrPSc elongation rate is strain-specific. The strains with fast elongation rates were expected to maintain the same amplification yield regardless of the length of incubation intervals between sonication cycles; whereas for the strains with slow elongation rates, the amplification yield was expected to decline with shortening of the incubation intervals. The experiments with brain-derived PrPSc revealed that the elongation rate was strain-specific. Furthermore, this work showed that strainspecific elongation rates could limit the overall amplification yield in a strain-dependent manner. Among the four strains compared, HY had the highest elongation rate, SSLOW showed the lowest rate, and LOTSS exhibited abnormal kinetic behavior. The abnormal kinetic pattern seen for brain-derived LOTSS PrPSc highlights the limitations of the current approach. Strains that are conformationally very stable are not susceptible to efficient fragmentation and are expected to deviate from conventional kinetic patterns. It is likely that LOTSS falls into this category.
While both SSLOW and LOTSS are deposited in animal brains in form of large plaques, LOTSS was found to be conformationally more stable than SSLOW and significantly more stable than 263K. To test whether the physical properties of a PrPSc population change during PMCAb amplification. The relative ranking order in elongation rates for the four strains was preserved after they were subjected to sPMCAb. HY displayed the fastest rate, 263K had intermediate rate, while SSLOW and LOTSS showed the slowest elongation rates. Remarkably, for each strain the elongation rate of PMCAbderived populations was higher than the corresponding rate of a brain-derived PrPSc population. Moreover, the abnormal kinetic pattern observed for brain-derived LOTSS transformed into a conventional pattern after sPMCAb.