The cellular prion protein interacts with and promotes the activity of Na,K-ATPases.
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ABSTRACT:
SUBMITTER: Williams D
PROVIDER: S-EPMC8631662 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:It is widely anticipated that a reduction of brain levels of the cellular prion protein (PrPC) can prolong survival in a group of neurodegenerative diseases known as prion diseases. To date, efforts to decrease steady-state PrPC levels by targeting this protein directly with small molecule drug-like compounds have largely been unsuccessful. Recently, we reported Na,K-ATPases to reside in immediate proximity to PrPC in the brain, unlocking an opportunity for an indirect PrPC targeting approach that capitalizes on the availability of potent cardiac glycosides (CGs). Here, we report that exposure of human co-cultures of neurons and astrocytes to non-toxic nanomolar levels of CGs causes profound reductions in PrPC levels. The mechanism of action underpinning this outcome relies primarily on a subset of CGs engaging the ATP1A1 isoform, one of three α subunits of Na,K-ATPases expressed in brain cells. Upon CG docking to ATP1A1, the ligand receptor complex, and PrPC along with it, is internalized by the cell. Subsequently, PrPC is channeled to the lysosomal compartment where it is digested in a manner that can be rescued by silencing the cysteine protease cathepsin B. These data signify that the repurposing of CGs may be beneficial for the treatment of prion disorders.
| S-EPMC9249225 | biostudies-literature
Project description:The products of the Brucella abortus virB gene locus, which are highly similar to conjugative DNA transfer system, enable the bacterium to replicate within macrophage vacuoles. The replicative phagosome is thought to be established by the interaction of a substrate of the VirB complex with macrophages, although the substrate and its host cellular target have not yet been identified. We report here that Hsp60, a member of the GroEL family of chaperonins, of B. abortus is capable of interacting directly or indirectly with cellular prion protein (PrPC) on host cells. Aggregation of PrPC tail-like formation was observed during bacterial swimming internalization into macrophages and PrPC was selectively incorporated into macropinosomes containing B. abortus. Hsp60 reacted strongly with serum from human brucellosis patients and was exposed on the bacterial surface via a VirB complex-associated process. Under in vitro and in vivo conditions, Hsp60 of B. abortus bound to PrPC. Hsp60 of B. abortus, expressed on the surface of Lactococcus lactis, promoted the aggregation of PrPC but not PrPC tail formation on macrophages. The PrPC deficiency prevented swimming internalization and intracellular replication of B. abortus, with the result that phagosomes bearing the bacteria were targeted into the endocytic network. These results indicate that signal transduction induced by the interaction between bacterial Hsp60 and PrPC on macrophages contributes to the establishment of B. abortus infection.
| S-EPMC2196088 | biostudies-literature
Project description:It is now well established that the conversion of the cellular prion protein, PrP(C), into its anomalous conformer, PrP(Sc), is central to the onset of prion disease. However, both the mechanism of prion-related neurodegeneration and the physiologic role of PrP(C) are still unknown. The use of animal and cell models has suggested a number of putative functions for the protein, including cell signaling, adhesion, proliferation, and differentiation. Given that skeletal muscles express significant amounts of PrP(C) and have been related to PrP(C) pathophysiology, in the present study, we used skeletal muscles to analyze whether the protein plays a role in adult morphogenesis. We employed an in vivo paradigm that allowed us to compare the regeneration of acutely damaged hind-limb tibialis anterior muscles of mice expressing, or not expressing, PrP(C). Using morphometric and biochemical parameters, we provide compelling evidence that the absence of PrP(C) significantly slows the regeneration process compared to wild-type muscles by attenuating the stress-activated p38 pathway, and the consequent exit from the cell cycle, of myogenic precursor cells. Demonstrating the specificity of this finding, restoring PrP(C) expression completely rescued the muscle phenotype evidenced in the absence of PrP(C).
| S-EPMC2950540 | biostudies-literature
Project description:The cellular prion protein (PrPC) is a highly conserved glycosylphosphatidylinositol (GPI)-anchored membrane protein that is involved in the signal transduction during the initial phase of neurite outgrowth. The Ras homolog gene family member A (RhoA) is a small GTPase that is known to have an essential role in regulating the development, differentiation, survival, and death of neurons in the central nervous system. Although recent studies have shown the dysregulation of RhoA in a variety of neurodegenerative diseases, the role of RhoA in prion pathogenesis remains unclear. Here, we investigated the regulation of RhoA-mediated signaling by PrPC using both in vitro and in vivo models and found that overexpression of PrPC significantly induced RhoA inactivation and RhoA phosphorylation in hippocampal neuronal cells and in the brains of transgenic mice. Using siRNA-mediated depletion of endogenous PrPC and overexpression of disease-associated mutants of PrPC, we confirmed that PrPC induced RhoA inactivation, which accompanied RhoA phosphorylation but reduced the phosphorylation levels of LIM kinase (LIMK), leading to cofilin activation. In addition, PrPC colocalized with RhoA, and the overexpression of PrPC significantly increased neurite outgrowth in nerve growth factor-treated PC12 cells through RhoA inactivation. However, the disease-associated mutants of PrPC decreased neurite outgrowth compared with wild-type PrPC. Moreover, inhibition of Rho-associated kinase (ROCK) substantially facilitated neurite outgrowth in NGF-treated PC12 cells, similar to the effect induced by PrPC. Interestingly, we found that the induction of RhoA inactivation occurred through the interaction of PrPC with RhoA and that PrPC enhanced the interaction between RhoA and p190RhoGAP (a GTPase-activating protein). These findings suggest that the interactions of PrPC with RhoA and p190RhoGAP contribute to neurite outgrowth by controlling RhoA inactivation and RhoA-mediated signaling and that disease-associated mutations of PrPC impair RhoA inactivation, which in turn leads to prion-related neurodegeneration.
| S-EPMC5386549 | biostudies-literature
Project description:Adult neurogenesis, analogous to early development, is comprised of several, often concomitant, processes including proliferation, differentiation, and formation of synaptic connections. However, due to continual, asynchronous turn-over, newly-born adult olfactory sensory neurons (OSNs) must integrate into existing circuitry. Additionally, OSNs express high levels of cellular prion protein (PrPC), particularly in the axon, which implies a role in this cell type. The cellular prion has been shown to be important for proper adult OSN neurogenesis primarily by stabilizing mature olfactory neurons within this circuitry. However, the role of PrPC on each specific adult neurogenic processes remains to be investigated in detail. To tease out the subtle effects of prion protein expression level, a large population of regenerating neurons must be investigated. The thyroid drug methimazole (MTZ) causes nearly complete OSN loss in rodents and is used as a model of acute olfactory injury, providing a mechanism to induce synchronized OSN regeneration. This study investigated the effect of PrPC on adult neurogenesis after acute nasotoxic injury. Altered PrPC levels affected olfactory sensory epithelial (OSE) regeneration, cell proliferation, and differentiation. Attempts to investigate the role of PrPC level on axon regeneration did not support previous studies, and glomerular targeting did not recover to vehicle-treated levels, even by 20 weeks. Together, these studies demonstrate that the cellular prion protein is critical for regeneration of neurons, whereby increased PrPC levels promote early neurogenesis, and that lack of PrPC delays the regeneration of this tissue after acute injury.
| S-EPMC6984647 | biostudies-literature
Project description:We used ELISA and flow cytometry to study the binding of prion protein PrP to glycosaminoglycans (GAGs). We found that recombinant human PrP (rPrP) binds GAGs including chondroitin sulphate A, chondroitin sulphate B, hyaluronic acid, and heparin. rPrP binding to GAGs occurs via the N-terminus, a region known to bind divalent cations. Additionally, rPrP binding to GAGs is enhanced in the presence of Cu2+ and Zn2+, but not Ca2+ and Mn2+. rPrP binds heparin strongest, and the binding is inhibited by certain heparin analogues, including heparin disaccharide and sulphate-containing monosaccharides, but not by acetylated heparin. Full-length normal cellular prion protein (PrPC), but not N-terminally truncated PrPC species, from human brain bind GAGs in a similar Cu2+/Zn2+-enhanced fashion. We found that GAGs specifically bind to a synthetic peptide corresponding to amino acid residues 23-35 in the N-terminus of rPrP. We further demonstrated that while both wild-type PrPC and an octapeptide-repeat-deleted mutant PrP produced by transfected cells bound heparin at the cell surface, the PrP N-terminal deletion mutant and non-transfectant control failed to bind heparin. Binding of heparin to wild-type PrPC on the cell surface results in a reduction of the level of cell-surface PrPC. These results provide strong evidence that PrPC is a surface receptor for GAGs.
| S-EPMC1222984 | biostudies-other
Project description:In the otherwise highly conserved NMR structures of cellular prion proteins (PrP(C)) from different mammals, species variations in a surface epitope that includes a loop linking a ?-strand, ?2, with a helix, ?2, are associated with NMR manifestations of a dynamic equilibrium between locally different conformations. Here, it is shown that this local dynamic conformational polymorphism in mouse PrP(C) is eliminated through exchange of Tyr169 by Ala or Gly, but is preserved after exchange of Tyr 169 with Phe. NMR structure determinations of designed variants of mouse PrP(121-231) at 20 °C and of wild-type mPrP(121-231) at 37 °C together with analysis of exchange effects on NMR signals then resulted in the identification of the two limiting structures involved in this local conformational exchange in wild-type mouse PrP(C), and showed that the two exchanging structures present characteristically different solvent-exposed epitopes near the ?2-?2 loop. The structural data presented in this paper provided a platform for currently ongoing, rationally designed experiments with transgenic laboratory animals for renewed attempts to unravel the so far elusive physiological function of the cellular prion protein.
| S-EPMC3198368 | biostudies-literature
Project description:Transmissible gastroenteritis virus (TGEV) is member of the family Coronaviridae and mainly causes acute diarrhea. TGEV infection is characterized by vomiting, watery diarrhea, and severe dehydration, resulting in high mortality rates in neonatal piglets. TGEV infection symptoms are related to an imbalance of sodium absorption in small intestinal epithelial cells; however, the etiology of sodium imbalance diarrhea caused by TGEV remains unclear. In this study, we performed transcriptomic analysis of intestinal tissues from infected and healthy piglets and observed that the expression of NHE3, encoding Na+/H+ exchanger 3 (NHE3), the main exchanger of electroneutral sodium in intestinal epithelial cells, was significantly reduced upon TGEV infection. We also showed that specific inhibition of intestinal NHE3 activity could lead to the development of diarrhea in piglets. Furthermore, we revealed an interaction between TGEV N protein and NHE3 near the nucleus. The binding of TGEV N to NHE3 directly affected the expression and activity of NHE3 on the cell surface and affected cellular electrolyte absorption, leading to diarrhea. Molecular docking and computer-aided screening techniques were used to screen for the blocker of the interaction between TGEV N and NHE3, which identified irinotecan. We then demonstrated that irinotecan was effective in relieving TGEV-induced diarrhea in piglets. These findings provide new insights into the mechanism of TGEV-induced sodium imbalance diarrhea and could lead to the design of novel antiviral strategies against TGEV. IMPORTANCE A variety of coronaviruses have been found to cause severe diarrhea in hosts, including TGEV; however, the pathogenic mechanism is not clear. Therefore, prompt determination of the mechanism and identification of efficient therapeutic agents are required, both for public health reasons and for economic development. In this study, we demonstrated that NHE3 is the major expressed protein of NHEs in the intestine, and its expression decreased by nearly 70% after TGEV infection. Also, specific inhibition of intestinal NHE3 resulted in severe diarrhea in piglets. This demonstrated that NHE3 plays an important role in TGEV-induced diarrhea. In addition, we found that TGEV N directly regulates NHE3 expression and activity through protein-protein interaction, which is essential to promote diarrhea. Molecular docking and other techniques demonstrated that irinotecan could block the interaction and diarrhea caused by TGEV. Thus, our results provide a basis for the development of novel therapeutic agents against TGEV and guidance for the development of drugs for other diarrhea-causing coronaviruses.
| S-EPMC9682987 | biostudies-literature
Project description:In Alzheimer disease amyloid-β (Aβ) peptides derived from the amyloid precursor protein (APP) accumulate in the brain. Cleavage of APP by the β-secretase BACE1 is the rate-limiting step in the production of Aβ. We have reported previously that the cellular prion protein (PrP(C)) inhibited the action of BACE1 toward human wild type APP (APP(WT)) in cellular models and that the levels of endogenous murine Aβ were significantly increased in PrP(C)-null mouse brain. Here we investigated the molecular and cellular mechanisms underlying this observation. PrP(C) interacted directly with the prodomain of the immature Golgi-localized form of BACE1. This interaction decreased BACE1 at the cell surface and in endosomes where it preferentially cleaves APP(WT) but increased it in the Golgi where it preferentially cleaves APP with the Swedish mutation (APP(Swe)). In transgenic mice expressing human APP with the Swedish and Indiana familial mutations (APP(Swe,Ind)), PrP(C) deletion had no influence on APP proteolytic processing, Aβ plaque deposition, or levels of soluble Aβ or Aβ oligomers. In cells, although PrP(C) inhibited the action of BACE1 on APP(WT), it did not inhibit BACE1 activity toward APP(Swe). The differential subcellular location of the BACE1 cleavage of APP(Swe) relative to APP(WT) provides an explanation for the failure of PrP(C) deletion to affect Aβ accumulation in APP(Swe,Ind) mice. Thus, although PrP(C) exerts no control on cleavage of APP(Swe) by BACE1, it has a profound influence on the cleavage of APP(WT), suggesting that PrP(C) may be a key protective player against sporadic Alzheimer disease.
| S-EPMC3190950 | biostudies-literature
Project description:The cellular prion protein (PrPC) has been associated with diverse biological processes including cell signaling, neurogenesis, and neuroprotection, but its physiological function(s) remain ambiguous. Here we determine the role of PrPC in adult neurogenesis using the olfactory system model in transgenic mice. Olfactory sensory neurons (OSNs) within the olfactory sensory epithelium (OSE) undergo neurogenesis, integration, and turnover even into adulthood. The neurogenic processes of proliferation, differentiation/maturation, and axon targeting were evaluated in wild type, PrP-overexpressing, and PrP-null transgenic mice. Our results indicate that PrPC plays a role in maintaining mature OSNs within the epithelium: overexpression of PrPC resulted in greater survival of mitotically active cells within the OSE, whereas absence of prion protein resulted in fewer cells being maintained over time. These results are supported by both quantitative PCR analysis of gene expression and protein analysis characteristic of OSN differentiation. Finally, evaluation of axon migration determined that OSN axon targeting in the olfactory bulb is PrPC dose-dependent. Together, these findings provide new mechanistic insight into the neuroprotective role for PrPC in adult OSE neurogenesis, whereby more mature neurons are stably maintained in animals expressing PrPC.
| S-EPMC5916339 | biostudies-literature