Cells employ several methods for recycling unwanted proteins and other material, including lysosomal and non-lysosomal pathways. The main lysosome-dependent pathway is called autophagy, while the primary non-lysosomal method for protein catabolism is the ubiquitin-proteasome system. Recent studies in model organisms suggest that the activity of both autophagy and the ubiquitin-proteasome system is not constant across the day but instead varies according to a daily (circadian) rhythm. The ability to measure biological rhythms in protein turnover is important for understanding how cellular quality control is achieved and for understanding the dynamics of specific proteins of interest. Here we present a standardized protocol for quantifying autophagic and proteasomal flux in vivo that captures the circadian component of protein turnover. Our protocol includes details for mouse handling, tissue processing, fractionation, and autophagic flux quantification using mouse liver as the starting material.
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http://dx.doi.org/10.3791/60133 | DOI Listing |
Cells
December 2024
Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla (US), 41012 Sevilla, Spain.
Autophagy is a catabolic process involved in different cellular functions. However, the molecular pathways governing its potential roles in different cell types remain poorly understood. We investigated the role of autophagy in the context of proteotoxic stress in two central nervous system cell types: the microglia-like cell line BV2 and the neuronal-like cell line N2a.
View Article and Find Full Text PDFJ Cell Mol Med
January 2025
School of Life Sciences, Anhui Medical University, Hefei, China.
Multiple myeloma (MM) is a haematological lymphoid malignancy marked by significant morbidity due to severe complications. Despite advances in targeted therapies, including proteasome inhibitors and the BCL-2 inhibitor venetoclax, drug resistance frequently occurs, with the underlying mechanisms poorly understood. This study investigates the role of lysosome-associated protein transmembrane 5 (LAPTM5) in conferring resistance to venetoclax in relapsed MM.
View Article and Find Full Text PDFJ Biol Chem
December 2024
The Laboratory of Ophthalmology and Vision Science, Department of Ophthalmology, The Joint National Laboratory of Antibody Drug Engineering, Henan Province Engineering Research Center of Fundus Disease and Ocular Trauma Prevention and Treatment, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China; Henan International Joint Research Laboratory for Ocular Immunology and Retinal Injury Repair, Zhengzhou, China; Kaifeng Key Lab for Cataracts and Myopia, Kaifeng Central Hospital, Kaifeng, China; Eye Institute, Henan Academy of Innovations in Medical Science, Zhengzhou, China. Electronic address:
Genetic mutations in retinol dehydrogenase 5 (RDH5), a rate-limiting enzyme of the visual cycle, is associated with nyctalopia, AMD and stationary congenital fundus albipunctatus (FA). A majority of these mutations impair RDH5 protein expression and intracellular localization. However, the regulatory mechanisms underlying RDH5 metabolism remain unclear.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden.
Aberration of mitochondrial function is a shared feature of many human pathologies, characterised by changes in metabolic flux, cellular energetics, morphology, composition, and dynamics of the mitochondrial network. While some of these changes serve as compensatory mechanisms to maintain cellular homeostasis, their chronic activation can permanently affect cellular metabolism and signalling, ultimately impairing cell function. Here, we use a Drosophila melanogaster model expressing a proofreading-deficient mtDNA polymerase (POLγ) in a genetic screen to find genes that mitigate the harmful accumulation of mtDNA mutations.
View Article and Find Full Text PDFChembiochem
December 2024
Department of Chemistry, Illinois State University, Normal, Il, USA.
Protein degradation is pivotal for all biochemical aspects of cellular function. In mammalian cells, protein degradation is mediated mainly by the ubiquitin proteasome system (UPS) and the autophagic-lysosomal system (ALS). Over the last two decades, different types of targeted protein degradation approaches have been developed including proteolysis targeting chimeras (PROTACs) and lysosome targeting chimeras (LYTACs), which employ the UPS to degrade intracellular proteins and the ALS to degrade extracellular and membrane proteins respectively.
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