Browsing by Subject "Transgenic Mice"

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    Gerstmann-Sträussler-Scheinker disease and "anchorless prion protein" mice share prion conformational properties diverging from sporadic Creutzfeldt-Jakob disease
    (ASBMB, 2014-02-21) Zanusso, Gianluigi; Fiorini, Michele; Ferrari, Sergio; Meade-White, Kimberly; Barbieri, Ilaria; Brocchi, Emiliana; Ghetti, Bernardino; Monaco, Salvatore; Department of Pathology & Laboratory Medicine, IU School of Medicine
    The role of the GPI-anchor in prion disease pathogenesis is still a challenging issue. In vitro studies have shown that anchorless cellular prion protein (PrP(C)) undergoes aberrant post-translational processing and metabolism. Moreover, transgenic (Tg) mice overexpressing anchorless PrP(C) develop a spontaneous neurological disease accompanied with widespread brain PrP amyloid deposition, in the absence of spongiform changes. Generation of PrP forms lacking the GPI and PrP amyloidosis are striking features of human stop codon mutations in the PrP gene (PRNP), associated with PrP cerebral amyloid angiopathy (PrP-CAA) and Gerstmann-Sträussler-Scheinker (GSS) syndrome. More recently, the presence of anchorless PrP species has been also claimed in sporadic Creutzfeldt-Jakob disease (sCJD). Using a highly sensitive protein separation technique and taking advantage of reference maps of synthetic PrP peptides, we investigated brain tissues from scrapie-infected "anchorless PrP" Tg mice and wild type mice to determine the contribution of the GPI-anchor to the molecular mass and isoelectric point of PrP quasispecies under two-dimensional electrophoresis. We also assessed the conformational properties of anchorless and anchored prions under standard and inactivating conditions. These studies were extended to sCJD and GSS. At variance with GSS, characterization of PrP quasispecies in different sCJD subtypes ruled out the presence of anchorless prions. Moreover, under inactivating conditions, mice anchorless prions, but not sCJD prions, generated internal PrP fragments, cleaved at both N and C termini, similar to those found in PrP-CAA and GSS brain tissues. These findings show that anchorless PrP(Sc) generates GSS-like PrP fragments, and suggest a major role for unanchored PrP in amyloidogenesis.
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    Osteoclast-mediated bone loss observed in a COVID-19 mouse model
    (2021-10-02) Awosanya, Olatundun D.; Dalloul, Christopher E.; Blosser, Rachel J.; Dadwal, Ushashi C.; Carozza, Mariel; Boschen, Karen; Klemsz, Michael J.; Johnston, Nancy A.; Bruzzaniti, Angela; Robinson, Christopher M.; Srour, Edward F.; Kacena, Melissa A.
    The consequences of SARS-CoV-2 infection on the musculoskeletal system represent a dangerous knowledge gap. Aging patients are at added risk for SARS-CoV-2 infection; therefore, a greater understanding of the resulting musculoskeletal sequelae of SARS-CoV-2 infection may help guide clinical strategies. This study examined fundamental bone parameters among mice treated with escalating viral loads. Male C57BL/6J (WT, n = 17) and B6.Cg-Tg(K18-ACE2)2Prlmn/J mice (K18-hACE2 transgenic mice, n = 21) expressing human ACE2 (TG) were divided into eight groups (n = 4-6/group) and subjected to intranasal dosing of 0, 1 × 103, 1 × 104, and 1 × 105 PFU (plaque forming units) of human SARS-CoV-2. Animal health was assessed daily by veterinary staff using established and validated scoring criteria (activity, posture, body condition scores and body weight). We report here that mock and WT infected mice were healthy and completed the study, surviving until 12-14 days post infection (dpi). In contrast, the TG mice infected with 1 × 105 PFU all experienced severe health declines that necessitated early euthanasia (6-7 dpi). For TG mice infected with 1 × 104 PFU, 2 mice were also euthanized after 7 dpi, while 3 mice showed signs of moderate disease at day 6 dpi, but recovered fully by day 11 dpi. Four of the 5 TG mice that were infected with 1 × 103 PFU remained healthy throughout the study. This suggests that our study mimics what is seen during human disease, where some patients develop severe disease resulting in death, while others have moderate to severe disease but recover, and others are asymptomatic. At necropsy, femurs were extracted and analyzed by μCT. No difference was found in μCT determined bone parameters among the WT groups. There was, however, a significant 24.4% decrease in trabecular bone volume fraction (p = 0.0009), 19.0% decrease in trabecular number (p = 0.004), 6.2% decrease in trabecular thickness (p = 0.04), and a 9.8% increase in trabecular separation (p = 0.04) among surviving TG mice receiving any viral load compared to non-infected controls. No differences in cortical bone parameters were detected. TRAP staining revealed surviving infected mice had a significant 64% increase in osteoclast number, a 27% increase in osteoclast surface, and a 38% increase in osteoclasts per bone surface. While more studies are needed to investigate the long-term consequences of SARS-CoV-2 infection on skeletal health, this study demonstrates a significant reduction in several bone parameters and corresponding robust increases in osteoclast number observed within 2 weeks post-infection in surviving asymptomatic and moderately affected mice.