The clustered regularly interspersed short palindromic repeat (CRISPR) gene-editing system has been repurposed for live-cell genomic imaging, but existing approaches rely on fluorescent protein reporters, making sensitive and continuous imaging difficult. Here, we present a fluorophore-based live-cell genomic imaging system that consists of a nuclease-deactivated mutant of the Cas9 protein (dCas9), a molecular beacon (MB), and an engineered single-guide RNA (sgRNA) harboring a unique MB target sequence (sgRNA-MTS), termed CRISPR/MB. Specifically, dCas9 and sgRNA-MTS are first co-expressed to target a specific locus in cells, followed by delivery of MBs that can then hybridize to MTS to illuminate the target locus. We demonstrated the feasibility of this approach for quantifying genomic loci, for monitoring chromatin dynamics, and for dual-color imaging when using two orthogonal MB/MTS pairs. With flexibility in selecting different combinations of fluorophore/quencher pairs and MB/MTS sequences, our CRISPR/MB hybrid system could be a promising platform for investigating chromatin activities.
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http://dx.doi.org/10.1093/nar/gky304 | DOI Listing |
Int J Mol Sci
January 2025
Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl. 21, 1113 Sofia, Bulgaria.
Replication forks encounter various impediments, which induce fork stalling and threaten genome stability, yet the precise dynamics of fork stalling and restart at the single-cell level remain elusive. Herein, we devise a live-cell microscopy-based approach to follow hydroxyurea-induced fork stalling and subsequent restart at 30 s resolution. We measure two distinct processes during fork stalling.
View Article and Find Full Text PDFFront Cell Dev Biol
January 2025
Endocrinology Research Centre, Institute of Personalized Medicine, Moscow, Russia.
Current dissociation methods for solid tissues in scRNA-seq studies do not guarantee intact single-cell isolation, especially for sensitive and complex human endocrine tissues. Most studies rely on enzymatic dissociation of fresh samples or nuclei isolation from frozen samples. Dissociating whole intact cells from fresh-frozen samples, commonly collected by biobanks, remains a challenge.
View Article and Find Full Text PDFClin Transl Med
January 2025
State Key Laboratory of Reproductive Medicine and Offspring Health, Nanjing Medical University, Nanjing, China.
Background: Numerous pathogenic variants causing human oocyte maturation arrest have been reported on the primate-specific TUBB8 gene. The main etiology is the dramatic reduction of tubulin α/β dimer, but still large numbers of variants remain unexplained.
Methods: Using microinjection mRNA and genome engineering to reintroduce the conserved pathogenic missense variants into oocytes or in generating TUBB8 variant knock-in mouse models, we investigated that the human deleterious variants alter microtubule nucleation and spindle assembly during meiosis.
bioRxiv
January 2025
Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033.
Retroviruses are responsible for significant pathology in humans and animals, including the acquired immunodeficiency syndrome and a wide range of malignancies. A crucial yet poorly understood step in the replication cycle is the recognition and selection of unspliced viral RNA (USvRNA) by the retroviral Gag protein, which binds to the psi (Ψ) packaging sequence in the 5' leader, to package it as genomic RNA (gRNA) into nascent virions. It was previously thought that Gag initially bound gRNA in the cytoplasm.
View Article and Find Full Text PDFJ Biol Chem
January 2025
Genomics Research Center, Academia Sinica, Taipei, Taiwan; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan; Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan; Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Institute of Biological Chemistry, Academia Sinica; Institute of Biochemical Sciences, National Taiwan University; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Taiwan University and Academia Sinica, Taipei, Taiwan. Electronic address:
Tauopathies cover a range of neurodegenerative diseases in which natively unfolded tau protein aggregates and spreads in the brain during disease progression. To gain insights into the mechanism of tau structure and spreading, here, we examined the biochemical and cellular properties of human full-length wild-type and familial mutant tau, ΔK280, with a deletion at lysine 280. Our results showed that both wild-type and mutant tau are predominantly monomeric by analytical ultracentrifugation.
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