Related Experiment Video
Updated: Nov 8, 2025
Exploring the Regulation of Lipid Droplet Catabolism through Lipophagy
Published on: January 31, 2025
Membranous Structures Directly Come in Contact With p62/SQSTM1 Bodies
Isei Tanida1, Tomohiro Haruta2, Mitsuo Suga2
1Department of Cellular and Molecular Neuropathology, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
Abstract:
During autophagy, autophagosomes are formed to engulf cytoplasmic contents. p62/SQSTM-1 is an autophagic adaptor protein that forms p62 bodies. A unique feature of p62 bodies is that they seem to directly associate with membranous structures. We first investigated the co-localization of mKate2-p62 bodies with phospholipids using click chemistry with propargyl-choline. Propargyl-choline-labeled phospholipids were detected inside the mKate2-p62 bodies, suggesting that phospholipids were present inside the bodies. To clarify whether or not p62 bodies come in contact with membranous structures directly, we investigated the ultrastructures of p62 bodies using in-resin correlative light and electron microscopy of the Epon-embedded cells expressing mKate2-p62. Fluorescent-positive p62 bodies were detected as uniformly lightly osmificated structures by electron microscopy. Membranous structures were detected on and inside the p62 bodies. In addition, multimembranous structures with rough endoplasmic reticulum-like structures that resembled autophagosomes directly came in contact with amorphous-shaped p62 bodies. These results suggested that p62 bodies are unique structures that can come in contact with membranous structures directly.
Insights
p62 bodies, crucial for autophagy, directly interact with cellular membranes and contain phospholipids. This study reveals their unique ability to associate with membranous structures during the autophagosome formation process.
Area of Science:
- Cell Biology
- Molecular Biology
- Autophagy Research
Background:
- Autophagy is a cellular process involving autophagosomes engulfing cytoplasmic material.
- p62/SQSTM-1 is an autophagic adaptor protein known to form p62 bodies.
- p62 bodies exhibit a unique characteristic of direct association with cellular membranes.
Purpose of the Study:
- To investigate the direct association of p62 bodies with membranous structures.
- To determine the presence of phospholipids within p62 bodies.
- To elucidate the ultrastructural relationship between p62 bodies and autophagosomes.
Main Methods:
- Co-localization studies using click chemistry to detect phospholipids within mKate2-p62 bodies.
- In-resin correlative light and electron microscopy (CLEM) of Epon-embedded cells expressing mKate2-p62.
- Ultrastructural analysis of p62 bodies and their interaction with membranous components.
Main Results:
- Phospholipids were detected within mKate2-p62 bodies, indicating their internal composition.
- Electron microscopy revealed membranous structures on and within p62 bodies.
- Amorphous p62 bodies were observed in direct contact with multimembranous structures resembling autophagosomes.
Conclusions:
- p62 bodies contain phospholipids and directly interact with cellular membranes.
- These findings highlight p62 bodies as unique structures involved in membrane association during autophagy.
- The direct contact suggests a role in the dynamic processes of autophagosome formation and cargo engulfment.
Related Concept Videos
01:38Intralumenal Vesicles and Multivesicular Bodies
01:30Assembly of Signaling Complexes
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
02:10Additional Subnuclear Structures
The nucleus contains many membrane-less subnuclear organelles or nuclear bodies, such as nucleoli, Cajal bodies, speckles,...
01:45Vesicular Tubular Clusters
With the help of motor proteins such...
01:45ER Retrieval Pathway
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
01:28Protein Translocation Machinery on 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...