Environmental polarity is an important factor that drives biomolecular interactions to regulate cell function. Herein, a general method of using the fluorogenic probe NTPAN-MI is reported to quantify the subcellular polarity change in response to protein unfolding. NTPAN-MI fluorescence is selectively activated upon labeling unfolded proteins with exposed thiols, thereby reporting on the extent of proteostasis. NTPAN-MI also reveals the collapse of the host proteome caused by influenza A virus infection. The emission profile of NTPAN-MI contains information of the local polarity of the unfolded proteome, which can be resolved through spectral phasor analysis. Under stress conditions that disrupt different checkpoints of protein quality control, distinct patterns of dielectric constant distribution in the cytoplasm can be observed. However, in the nucleus, the unfolded proteome was found to experience a more hydrophilic environment across all the stress conditions, indicating the central role of nucleus in the stress response process.
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http://dx.doi.org/10.1002/anie.201914263 | DOI Listing |
Mol Ther
January 2025
Program of Cellular and Molecular Biology, Biomedical Sciences Institute (ICBM), Universidad de Chile, Santiago, Chile; Biomedical Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile; FONDAP Center for Geroscience, Brain Health and Metabolism, Santiago, Chile; Buck Institute for Research on Aging, Novato, CA, USA. Electronic address:
Amyotrophic lateral sclerosis (ALS) and fronto-temporal dementia (FTD) are part of a spectrum of diseases that share several causative genes, resulting in a combinatory of motor and cognitive symptoms and abnormal protein aggregation. Multiple unbiased studies have revealed that proteostasis impairment at the level of the endoplasmic reticulum (ER) is a transversal pathogenic feature of ALS/FTD. The transcription factor XBP1s is a master regulator of the unfolded protein response (UPR), the main adaptive pathway to cope with ER stress.
View Article and Find Full Text PDFGenes Dev
December 2024
Institute for Diabetes, Obesity, and Metabolism, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19146, USA;
The Cullin-3 E3 ligase adaptor protein SPOP targets proteins for ubiquitination and proteasomal degradation. We previously established the β-cell transcription factor (TF) and human diabetes gene PDX1 as an SPOP substrate, suggesting a functional role for SPOP in the β cell. Here, we generated a β-cell-specific deletion mouse strain ( ) and found that is necessary to prevent aberrant basal insulin secretion and for maintaining glucose-stimulated insulin secretion through impacts on glycolysis and glucose-stimulated calcium flux.
View Article and Find Full Text PDFBiol Open
January 2025
Department of Pulmonary Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Epithelial cell cohesion and barrier function critically depend on α-catenin, an actin-binding protein and essential constituent of cadherin-catenin-based adherens junctions. α-catenin undergoes actomyosin force-dependent unfolding of both actin-binding and middle domains to strongly engage actin filaments and its various effectors; this mechanosensitivity is critical for adherens junction function. We previously showed that α-catenin is highly phosphorylated in an unstructured region that links the mechanosensitive middle and actin-binding domains (known as the P-linker region), but the cellular processes that promote α-catenin phosphorylation have remained elusive.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
Key Laboratory of Forest Food Resources Utilization of Heilongjiang Province, Harbin 150040, China; College of Life Sciences, Northeast Forestry University, Harbin 150040, China. Electronic address:
The present study investigated the covalent binding behavior of the flavonoids, catechin, eriodictyol, luteolin and quercetin with β-lactoglobulin (βlg). Since the four flavonoids possess the identical A- and B-ring structures, effects of the C-rings on the properties of flavonoids and the corresponding semiquinones are revealed. Experimental methods including DLS and CD spectra indicated that with quercetin at room temperature did not induce aggregation of βlg, whilst binding with the other three flavonoids resulted in aggregation of βlg.
View Article and Find Full Text PDFComp Biochem Physiol Part D Genomics Proteomics
December 2024
Institute of Animal Husbandry and Veterinary, Tibet Autonomous Regional Academy of Agricultural Sciences, Lhasa, Tibet 850000, China. Electronic address:
Yak meat plays a significant economic role for yaks. The unique environment of the Qinghai-Tibet plateau profoundly impacts the meat production performance of yaks. Yet, the regulatory mechanisms influencing muscle growth and development in yaks within this plateau environment remain poorly understood.
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