Dominant-negative p53-overexpression in skeletal muscle induces cell death and fiber atrophy in rats

The tumor suppressor p53 is thought to play a key role in the maintenance of cell size and homeostasis, but relatively little is known about its role in skeletal muscle. Based on its ability to suppress cell growth, we hypothesized that inhibiting the function of wild-type p53 through the overexpression of a dominant-negative p53 mutant (DDp53) could result in muscle fiber hypertrophy. To test this hypothesis, we electroporated adult rat tibialis anterior muscles with DDp53 and collected the tissue three weeks later. We confirmed successful overexpression of DDp53 on a histological and biochemical level and found pronounced changes to muscle architecture, metabolism, and molecular signaling. Muscle mass, fiber cross-sectional area, and fiber diameter significantly decreased with DDp53 overexpression. We found histopathological changes in DDp53 transfected muscle which were accompanied by increased levels of proteins that are associated with membrane damage and repair. In addition, DDp53 decreased oxidative phosphorylation complex I and V protein levels, and despite its negative effects on muscle mass and fiber size, caused an increase in muscle protein synthesis as assessed via the SUnSET technique. Interestingly, the increase in muscle protein synthesis was concomitant with a decrease in phospho-S6K1 (Thr389). Furthermore, the muscle wasting in the DDp53 electroporated leg was accompanied by a decrease in global protein ubiquitination and an increase in proteasome activity. In conclusion, overexpression of a dominant-negative p53 mutant in skeletal muscle results in decreased muscle mass, myofiber size, histological muscle damage, a metabolic phenotype, and perturbed homeostasis between muscle protein synthesis and degradation.Subject terms: Proteasome, Phosphorylation, Contractile proteins     

Structure-selected RBM immunogens prime polyclonal memory responses that neutralize SARS-CoV-2 variants of concern

Successful control of the COVID-19 pandemic depends on vaccines that prevent transmission. The full-length Spike protein is highly immunogenic but the majority of antibodies do not target the virus: ACE2 interface. In an effort to affect the quality of the antibody response focusing it to the receptor-binding motif (RBM) we generated a series of conformationally-constrained immunogens by inserting solvent-exposed RBM amino acid residues into hypervariable loops of an immunoglobulin molecule. Priming C57BL/6 mice with plasmid (p)DNA encoding these constructs yielded a rapid memory response to booster immunization with recombinant Spike protein. Immune sera antibodies bound strongly to the purified receptor-binding domain (RBD) and Spike proteins. pDNA primed for a consistent response with antibodies efficient at neutralizing authentic WA1 virus and three variants of concern (VOC), B.1.351, B.1.617.2, and BA.1. We demonstrate that immunogens built on structure selection can be used to influence the quality of the antibody response by focusing it to a conserved site of vulnerability shared between wildtype virus and VOCs, resulting in neutralizing antibodies across variants.     

A multi-criteria decision-making model for classifying wood products with respect to their impact on environment

Background, aim and scope  

Although life cycle assessment is frequently used in scientific studies of product comparison, many practitioners are looking for improvements in the normalisation, grouping and weighting of life cycle inventory results. Local conditions, which are well known to local experts, are very important to these steps. The goal of this work was to develop a computer-based decision support system for classifying wood products according to their influence on the environment in their whole life cycle. The model specifically addresses local conditions in the Republic of Slovenia and was developed by Slovenian experts.     

Hen egg white lysozyme fibrillation: a deep‐UV resonance Raman spectroscopic study

Amyloid fibrils are associated with numerous degenerative diseases. The molecular mechanism of the structural transformation of native protein to the highly ordered cross‐β structure, the key feature of amyloid fibrils, is under active investigation. Conventional biophysical methods have limited application in addressing the problem because of the heterogeneous nature of the system. In this study, we demonstrated that deep‐UV resonance Raman (DUVRR) spectroscopy in combination with circular dichroism (CD) and intrinsic tryptophan fluorescence allowed for quantitative characterization of protein structural evolution at all stages of hen egg white lysozyme fibrillation in vitro. DUVRR spectroscopy was found to be complimentary to the far‐UV CD because it is (i) more sensitive to β ‐sheet than to α ‐helix, and (ii) capable of characterizing quantitatively inhomogeneous and highly light‐scattering samples. In addition, phenylalanine, a natural DUVRR spectroscopic biomarker of protein structural rearrangements, exhibited substantial changes in the Raman cross section of the 1000‐cm^–1 band at various stages of fibrillation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Molecular chaperones in biology and medicine at Obernai

No Abstract Available