The S(MK) (SAM-III) box is an S-adenosylmethionine (SAM)-responsive riboswitch found in the 5' untranslated region of metK genes, encoding SAM synthetase, in many members of the Lactobacillales. SAM binding causes a structural rearrangement in the RNA that sequesters the Shine-Dalgarno (SD) sequence by pairing with a complementary anti-SD (ASD) sequence; sequestration of the SD sequence inhibits binding of the 30S ribosomal subunit and prevents translation initiation. We observed a slight increase in the half-life of the metK transcript in vivo when Enterococcus faecalis cells were depleted for SAM, but no significant change in overall transcript abundance, consistent with the model that this riboswitch regulates at the level of translation initiation. The half-life of the SAM-S(MK) box RNA complex in vitro is shorter than that of the metK transcript in vivo, raising the possibility of reversible binding of SAM. We used a fluorescence assay to directly visualize reversible switching between the SAM-free and SAM-bound conformations. We propose that the S(MK) box riboswitch can make multiple SAM-dependent regulatory decisions during the lifetime of the transcript in vivo, acting as a reversible switch that allows the cell to respond rapidly to fluctuations in SAM pools by modulating expression of the SAM synthetase gene.
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http://dx.doi.org/10.1111/j.1365-2958.2010.07410.x | DOI Listing |
Sci Rep
January 2025
Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, United States.
There are few in vitro models available to study microglial physiology in a homeostatic context. Recent approaches include the human induced pluripotent stem cell model, but these can be challenging for large-scale assays and may lead to batch variability. To advance our understanding of microglial biology while enabling scalability for high-throughput assays, we developed an inducible immortalized murine microglial cell line using a tetracycline expression system.
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January 2025
Neuroscience and Ophthalmology, Department of Inflammation and Ageing, School of Infection, Inflammation and Immunology, College of Medicine and Health, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Spinal cord injury (SCI) is a significant cause of lifelong disability, with no available disease-modifying treatments to promote neuroprotection and axon regeneration after injury. Photobiomodulation (PBM) is a promising therapy which has proven effective at restoring lost function after SCI in pre-clinical models. However, the precise mechanism of action is yet to be determined.
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January 2025
Department of Hematology and Oncology, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatric Metabolism and Inflammatory Diseases, Children's Hospital of Chongqing Medical University, No 136 Zhongshan 2 road, YuZhong district, Chongqing, 400014, China.
Genetic alterations play a pivotal role in leukemic clonal transformation, significantly influencing disease pathogenesis and clinical outcomes. Here, we report a novel fusion gene and investigate its pathogenic role in acute lymphoblastic leukemia (ALL). We engineer a transposon transfection system expressing the TOP2B::AFF2 transcript and introduce it into Ba/F3 cells.
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December 2025
Department of Thyroid Head and Neck Surgery, The Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou, China.
Background: Exosomes derived from cancer-associated fibroblasts (CAFs) can affect tumor microenvironment (TME) of thyroid cancer (TC). The cAMP response element binding protein 1 (CREB1) acts as a transcription factor to participate in cancer development. Currently, we aimed to explore the molecular mechanism of exosome-associated CREB1 and C-C motif chemokine ligand 20 (CCL20) in TC.
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January 2025
Type 2 Immunity Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
How macrophages in the tissue environment integrate multiple stimuli depends on the genetic background of the host, but this is still poorly understood. We investigate IL-4 activation of male C57BL/6 and BALB/c strain specific in vivo tissue-resident macrophages (TRMs) from the peritoneal cavity. C57BL/6 TRMs are more transcriptionally responsive to IL-4 stimulation, with induced genes associated with more super enhancers, induced enhancers, and topologically associating domains (TAD) boundaries.
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