Related Experiment Video
Updated: Jul 13, 2026
09:33
Methods to Classify Cytoplasmic Foci as Mammalian Stress Granules
Published on: May 12, 2017
The exon-junction-complex-component metastatic lymph node 51 functions in stress-granule assembly.
Aurélie Baguet1, Sébastien Degot, Nicolas Cougot
1Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Département de Biologie du Cancer, UMR 7104 CNRS/U596 INSERM/Université Louis Pasteur, BP 10142, 67404 Illkirch, C.U. de Strasbourg, France.
Journal of Cell Science
|July 27, 2007
Summary
Metastatic lymph node 51 (MLN51) is part of the exon junction complex. This study reveals MLN51 also localizes to cytoplasmic stress granules, impacting their assembly and potentially occurring in breast cancer.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Metastatic lymph node 51 (MLN51), also known as CASC3, is a core component of the exon junction complex (EJC).
- The EJC is crucial for post-splicing mRNA processing, with its core proteins shuttling between the nucleus and cytoplasm.
- MLN51's predominant cytoplasmic localization suggests functions beyond its role in the EJC.
Purpose of the Study:
- To investigate the cytoplasmic functions of MLN51.
- To determine MLN51's association with cytoplasmic structures like stress granules (SGs).
- To explore the implications of MLN51's role in SGs in the context of human breast carcinomas.
Main Methods:
- Immunofluorescence microscopy to visualize MLN51 localization.
- Co-immunoprecipitation assays to study protein interactions.
- RNA interference (RNAi) and overexpression studies to assess MLN51 function in SG assembly.
- Analysis of patient tumor samples.
Main Results:
- MLN51 is recruited to cytoplasmic stress granules (SGs) along with SG-resident proteins like FMRP and PABP.
- MLN51 specifically binds to SGs via its C-terminal region, which is not essential for EJC incorporation.
- MLN51 is not a direct inducer of SG formation, but its depletion or mutation of the C-terminal region disrupts SG assembly.
- Cytoplasmic foci positive for MLN51, FMRP, and PABP are observed in human breast carcinomas, suggesting SG formation in tumors.
Conclusions:
- MLN51 possesses a dual role, participating in both the EJC and cytoplasmic stress granules.
- The C-terminal region of MLN51 is critical for its interaction with SGs and influences SG assembly.
- Stress granule formation involving MLN51 may occur in malignant tumors, indicating a potential role in cancer progression.
Related Concept Videos
02:19The Spindle Assembly Checkpoint
The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
01:26Tension Response at Adherens Junctions
The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin homology) domains...
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin homology) domains...
01:32Assembly of Complex Microtubule Structures
Complex microtubule structures are present in resting cells and in dividing cells. In resting cells, they are responsible for maintaining the cellular architecture, tracks for intracellular transport, positioning of organelles, assembly of cilia and flagella. They mediate the bipolar spindle assembly for chromosomal segregation and positioning of the cell division plate in dividing cells. The formation of microtubule complex structures depends on the cell type, cell stage, and cell function.
02:50Spindle Assembly
Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
01:31Regulation of the Unfolded Protein Response
Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...