The studies of prions and prion disease usually need many special platforms and techniques that differ from those for classical microbes. Search of new biomarkers and establishment of new methods for the diagnosis of human prion diseases are priorities in the field of prion study.

Wilforine, a compound of sesquiterpene alkaloids isolated from Tripterygium wilfordii, exhibits excellent insecticidal activity against Mythimna separata. In order to clarify the action mechanism of wilforine, the plasma membrane calcium transporting ATPase (PMCA) and inositol 1,4,5-trisphosphate receptor (IP3R) from M. separata were studied. Results showed that the open reading frame of MsIP3R and MsPMCA were 8118 bp and 3438 bp in length, as well as encoded 2706 and 1146 amino acids, respectively. Multiple sequence alignment and phylogenetic analysis revealed that the MsIP3R and MsPMCA had high homology with the IP3R and PMCA of other insects, but had low similarity with those of mammals, which means the IP3R and PMCA have potential to be the novel targets of insecticides with high selectivity between mammals and insects. Both MsIP3R and MsPMCA genes existed throughout the life cycle of M. separata, and were all predominantly expressed in somatic muscle of fifth-instar larvae and the adults. The susceptibilities of PMCA-silenced M. separata to wilforine were significantly lower than that of the normal M. separata, which illustrates that PMCA could be one of the targets of wilforine. However, the susceptibilities of IP3R-silenced M. separata to wilforine did not change significantly compared with the susceptibilities of normal M. separata, which shows that wilforine may not interact with the IP3R protein. These findings provide clues for elucidating the insecticidal mechanism of wilforine.

Diabetes is known to predispose patients to the development of the life-threatening disorder pancreatitis and to cause a more severe course of pancreatitis. However, the mechanistic link between diabetes and pancreatitis is not clear. Aberrant cytosolic Ca2+ signals within the main parenchymal cell of the pancreas, the acinar cells, are central to the initiation of pancreatitis and can modulate its severity. The acinar cell Ca2+ signals are tightly regulated by a Ca2+ toolbox, which includes the plasma membrane Ca2+-ATPase (PMCA). A new paper by Bruce et al. shows that active extrusion of Ca2+through the PMCA protects acinar cells against the damage of pancreatitis in the setting of diabetes. The novelty of the finding here is that insulin receptors on the acinar cell transduce a glycolytic supply of ATP to fuel the PMCA and, thereby, link diabetes to pancreatitis through Ca2+signaling.

Resveratrol shows the ability to block prion replication in a scrapie-infected cell line, SMB-S15, and remove the infectivity of the treated cell lysates in an experimental bioassay. In this study, we compared the effectiveness of three stilbene compounds, resveratrol (Res), pterostilbene (Pte), and piceatannol (Pic), on inhibiting prion propagations in the levels of cell culture, PMCA, and RT-QuIC. All three chemicals showed active suppressions on PrPSc replication in SMB-S15 cells, in which Res seemed to be the most active one, followed by Pic and Pte. Mouse PrP-based PMCA tests using the lysates of SMB-S15 cells and brain homogenates of scrapie agents S15-, 139A-, or ME7-infected mice verified that Res, Pte, and Pic inhibited the amplifications of PK-resistant signals. Res was also the most effective one. Mouse PrP-based RT-QuIC using the above seeds demonstrated that three stilbenes efficiently inhibited the fibril formation. However, Pic was the most effective one, followed by Res and Pte. Furthermore, the inhibition activities of the three stilbenes on the brain-derived prion from a 263K-infected hamster were tested with hamster PrP-based PMCA and RT-QuIC. The results indicated that Pic was the most effective one apparently, followed by Res and Pte. According to the results of Biacore, Res showed binding affinities much stronger than those of Pte, whereas both revealed markedly stronger binding affinities with mouse PrP. Our data here indicate that different stilbenes have the ability to block PrPSc replication in vitro with different prion species. The suppressive effects of stilbene compounds are likely associated with their molecular binding activities with PrPs.

BACKGROUND: Familial spastic paraplegia (FSP) is a heterogeneous group of disorders characterized primarily by progressive lower limb spasticity and weakness. More than 50 disease loci have been described with different modes of inheritance. Recently, we described a novel missense mutation (c.803G>A, p.R268Q) in the plasma membrane calcium ATPase (PMCA4, or ATP2B4) gene in a Chinese family with autosomal dominant FSP. Further to this finding, here we describe the functional effect of this mutation.
METHODS: As PMCA4 removes cytosolic calcium, we measured transient changes and the time-dependent decay of cytosolic calcium level as visualized by using fura-2 fluorescent dye with confocal microscopy in human SH-SY5Y neuroblastoma cells overexpressing either wild-type or R268Q mutant PMCA4.
RESULTS: Overexpressing both wild-type and R268Q PMCA4 significantly reduced maximum calcium surge after KCl-induced depolarization as compared with vector control cells. However, cells overexpressing mutant PMCA4 protein demonstrated significantly higher level of calcium surge when compared with wild-type. Furthermore, the steady-state cytosolic calcium concentration in these mutant cells remained markedly higher than the wild-type after SERCA inhibition by thapsigargin.
CONCLUSIONS: Our result showed that p.R268Q mutation in PMCA4 resulted in functional changes in calcium homeostasis in human neuronal cells. This suggests that calcium dysregulation may be associated with the pathogenesis of FSP.