Degradation of I kappaB (κB) inhibitors is critical to activation of dimeric transcription factors of the NF-κB family. There are two types of IκB inhibitors: the prototypical IκBs (IκBα, IκBβ, and IκBε), which form low-molecular-weight (MW) IκB:NF-κB complexes that are highly stable, and the precursor IκBs (p105/IκBγ and p100/IκBδ), which form high-MW assemblies, thereby suppressing the activity of nearly half the cellular NF-κB [Savinova OV, Hoffmann A, Ghosh G (2009) Mol Cell 34(5):591-602]. The identity of these larger assemblies and their distinct roles in NF-κB inhibition are unknown. Using the X-ray crystal structure of the C-terminal domain of p100/IκBδ and functional analysis of structure-guided mutants, we show that p100/IκBδ forms high-MW (IκBδ)4:(NF-κB)4 complexes, referred to as kappaBsomes. These IκBδ-centric "kappaBsomes" are distinct from the 2:2 complexes formed by IκBγ. The stability of the IκBδ tetramer is enhanced upon association with NF-κB, and hence the high-MW assembly is essential for NF-κB inhibition. Furthermore, weakening of the IκBδ tetramer impairs both its association with NF-κB subunits and stimulus-dependent processing into p52. The unique ability of p100/IκBδ to stably interact with all NF-κB subunits by forming kappaBsomes demonstrates its importance in sequestering NF-κB subunits and releasing them as dictated by specific stimuli for developmental programs.
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http://dx.doi.org/10.1073/pnas.1408552111 | DOI Listing |
Skelet Muscle
January 2025
Department of Molecular Physiology and Biophysics, and Department of Neurology, Howard Hughes Medical Institute, Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, USA.
Background: Maintaining the connection between skeletal muscle fibers and the surrounding basement membrane is essential for muscle function. Dystroglycan (DG) serves as a basement membrane extracellular matrix (ECM) receptor in many cells, and is also expressed in the outward-facing membrane, or sarcolemma, of skeletal muscle fibers. DG is a transmembrane protein comprised of two subunits: alpha-DG (α-DG), which resides in the peripheral membrane, and beta-DG (β-DG), which spans the membrane to intracellular regions.
View Article and Find Full Text PDFBMC Genomics
January 2025
State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
Infectious spleen and kidney necrosis virus (ISKNV) is a highly virulent and rapidly transmissible fish virus that poses threats to the aquaculture of a wide variety of freshwater and marine fish. N6-methyladenosine (mA), recognized as a common epigenetic modification of RNA, plays an important regulatory role during viral infection. However, the impact of mA RNA methylation on the pathogenicity of ISKNV remains unexplored.
View Article and Find Full Text PDFCommun Biol
January 2025
State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, Sichuan, P. R. China.
Uncoupling protein 1 (UCP1) is a crucial protein located in the mitochondrial inner membrane that mediates nonshivering thermogenesis. However, the molecular mechanisms by which enhancer-promoter chromatin interactions control Ucp1 transcriptional regulation in brown adipose tissue (BAT) are unclear. Here, we employed circularized chromosome conformation capture coupled with next-generation sequencing (4C-seq) to generate high-resolution chromatin interaction profiles of Ucp1 in interscapular brown adipose tissue (iBAT) and epididymal white adipose tissue (eWAT) and revealed marked changes in Ucp1 chromatin interaction between iBAT and eWAT.
View Article and Find Full Text PDFSci Rep
January 2025
Laboratory of Biochemistry, College of Veterinary Medicine, Chungnam National University, 99 Daehak-Ro, Yuseong-Gu, Daejeon, 34134, Korea.
The mechanisms underlying exercise-induced insulin sensitization are of great interest, as exercise is a clinically critical intervention for diabetic patients. Some microRNAs (miRs) are secreted from skeletal muscle after exercise where they regulate insulin sensitivity, and have potential as diagnostic markers in diabetic patients. miR-204 is well-known for its involvement in development, cancer, and metabolism; however, its role in exercise-induced glycemic control remains unclear.
View Article and Find Full Text PDFNat Struct Mol Biol
January 2025
Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
Many protein complexes are highly dynamic in cells; thus, characterizing their conformational changes in cells is crucial for unraveling their functions. Here, using cryo-electron microscopy, 451,700 ribosome particles from Saccharomyces cerevisiae cell lamellae were obtained to solve the 60S region to 2.9-Å resolution by in situ single-particle analysis.
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