Timely progression into mitosis is necessary for normal cell division. This transition is sensitive to the levels of cyclin B, the regulatory subunit of the master mitotic kinase, Cdk1. Cyclin B accumulates during G2 and prophase when its rate of destruction by the anaphase promoting complex (APC) is low. Securin is also an APC substrate and is known for its role in inactivating the cohesin-cleaving enzyme, separase, until the metaphase to anaphase transition. Here we show that securin has an additional role in cell-cycle regulation, that of modulating the timing of entry into M-phase. In mouse oocytes, excess securin caused stabilization of cyclin B and precocious entry into M-phase. Depletion of securin increased cyclin B degradation, resulting in delayed progression into M-phase. This effect required APC activity and was reversed by expression of wild-type securin. These data reveal a role for securin at the G2-M transition and suggest a more general mechanism whereby physiological levels of co-competing APC substrates function in modulating the timing of cell-cycle transitions.
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http://dx.doi.org/10.1038/ncb1707 | DOI Listing |
J Cachexia Sarcopenia Muscle
February 2025
Meakins-Christie Laboratories and Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
Background: COVID-19 has been associated with both respiratory (diaphragm) and non-respiratory (limb) muscle atrophy. It is unclear if SARS-CoV-2 infection of skeletal muscle plays a role in these changes. This study sought to: 1) determine if cells comprising skeletal muscle tissue, particularly myofibres, express the molecular components required for SARS-CoV-2 infection; 2) assess the capacity for direct SARS-CoV-2 infection and its impact on atrophy pathway genes in myogenic cells; and 3) in an animal model of COVID-19, examine the relationship between viral infection of skeletal muscle and myofibre atrophy within the diaphragm and limb muscles.
View Article and Find Full Text PDFMol Ther
January 2025
Department of Surgery, University of California San Diego, La Jolla, CA, 92093, United States; Department of Dermatology, University of California San Diego, La Jolla, CA, 92093, United States. Electronic address:
Small extracellular vesicles (sEVs) mediate intercellular signaling to coordinate proliferation of cell types that promote re-epithelialization of skin following injury. Cyclin-dependent kinase 1 (CDK1) drives cell division and is a key regulator of entry to cell cycle. To understand the potential of sEV-mediated delivery of CDK1 to reverse impaired wound healing, we generated CDK1-loaded sEVs (CDK1-sEVs) and evaluated their ability to mediate cell proliferation, re-epithelialization and downstream signaling responses in the wound bed.
View Article and Find Full Text PDFExp Cell Res
January 2025
Guangdong Provincial Key Laboratory of Research and Development of Natural Drugs, School of Pharmacy, Guangdong Medical University, Zhanjiang, Guangdong, 524023, China. Electronic address:
To investigate the effect of a novel coumarin derivative, ethyl 2,2-difluoro-2 - (2-oxo-2H-chromen-3-yl) acetate (C2F), on the malignant biological behaviors of colorectal cancer (CRC) and elucidate its mechanism. In vitro, the effects of C2F on the proliferation, apoptosis, migration, invasion, and cell cycle of CRC cells were analyzed by MTT assay, EdU stainning, colony formation assay, flow cytometry, wound healing and transwell assay. The anti-CRC activity of C2F was evaluated in a nude mice xenograft model in vivo.
View Article and Find Full Text PDFmBio
January 2025
Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Unlabelled: Interlinked interactions between the viral capsid (CA), nucleoporins (Nups), and the antiviral protein myxovirus resistance 2 (MX2/MXB) influence human immunodeficiency virus 1 (HIV-1) nuclear entry and the outcome of infection. Although RANBP2/NUP358 has been repeatedly identified as a critical player in HIV-1 nuclear import and MX2 activity, the mechanism by which RANBP2 facilitates HIV-1 infection is not well understood. To explore the interactions between MX2, the viral CA, and RANBP2, we utilized CRISPR-Cas9 to generate cell lines expressing RANBP2 from its endogenous locus but lacking the C-terminal cyclophilin (Cyp) homology domain and found that both HIV-1 and HIV-2 infections were reduced significantly in RANBP2 cells.
View Article and Find Full Text PDFHepatology
January 2025
Genome Medical Science Project, National Center for Global Health and Medicine, Ichikawa, Japan.
Background Aims: Hepatitis B virus (HBV) leads to severe liver diseases, such as cirrhosis and hepatocellular carcinoma. Identification of host factors that regulate HBV replication can provide new therapeutic targets. The discovery of sodium taurocholate cotransporting polypeptide (NTCP) as an HBV entry receptor has enabled the establishment of hepatic cell lines for analyzing HBV infection and propagation.
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