Previous molecular dynamic simulations have reported elongation of the existing beta-sheet in prion proteins. Detailed examination has shown that these elongations do not extend beyond the proline residues flanking these beta-sheets. In addition, proline has also been suggested to possess a possible structural role in preserving protein interaction sites by preventing invasion of neighboring secondary structures. In this work, we have studied the possible structural role of the flanking proline residues by simulating mutant structures with alternate substitution of the proline residues with valine. Simulations showed a directional inhibition of elongation, with the elongation progressing in the direction of valine including evident inhibition of elongation by existing proline residues. This suggests that the flanking proline residues in prion proteins may have a containment role and would confine the beta-sheet within a specific length.
Currently, fetal bovine serum (FBS) have been widely use in culture media to promote human cell proliferation. However,
the usage of FBS for cell therapy in clinical application was associated with the risk of viral and prion transmission as
well as immune rejection. To provide an option for this risk, this study was conducted to determine the effect of adipose
derived stem cells (ADSCs) co-culture with chondrocyte in promoting cell proliferation and chondrogenesis toward
FBS free condition. ADSCs co-cultured with chondrocyte at the ratio of 1:1, 2:1 and 1:2 were tested. Cell morphology
changes, cell proliferation and gene expression level of stemness (Oct4, FGF-4, Nanog) and chondrogenic (Collagen
Type II, ACP) were assessed. The results showed ADSCs in all co-culture groups changed morphology from fibroblastic
spindle to polygonal shape which resembled chondrocytes. The morphological changes were accompanied with increased
expression of chondrogenic genes; denoted chondrogenesis process. While maintaining expression of stemness genes
indicated continuation of cell proliferation. From the three co-culture groups tested; ADSCs and chondrocytes (1:1 ratio)
have been shown to exert better effects in promoting cell proliferation and chondrogenesis. In conclusion, ADSCs could
replace FBS to grow sufficient number of chondrogenic cells to repair cartilage injury in the near future. Further in vivo
study should be performed to test the effectiveness of this co-culture technique in cartilage injury repair.
Most studies have focused on the role of the cellular prion protein (PrP(C)) in neurodegenerative diseases, whereas the function of this ubiquitous protein outside the nervous system remains elusive. Therefore, the anti-apoptotic property of PrP(C) in oral squamous cell carcinoma (HSC-2) and colon adenocarcinoma (LS 174T) was evaluated in this study, by stable shRNA knockdown and overexpression, respectively. PrP(C) confers resistance against oxidative stress-apoptosis as indicated by MTT assay, Annexin V-FITC/PI and DCFH-DA staining, but this property is abolished upon N-glycosylation inhibition by tunicamycin. Our results indicate that the inhibition of glycosylation in cancer cells overexpressing PrP(C) could represent a potential therapeutic target.