Dense-core vesicles contain exosomes in secretory cells.
Xin Wang1, Gianvito Arpino1, Ammar Mohseni1
1National Institute of Neurological Disorders and Stroke, Bethesda, Maryland.
Biophysical Journal
|January 15, 2025
Summary
Dense-core vesicles (DCVs) in cells do not have halos as previously thought. These vesicles contain exosomes, suggesting a new pathway for exosome release and intercellular communication.
Area of Science:
- Cell Biology
- Neuroscience
- Endocrinology
Background:
- Dense-core vesicles (DCVs) are crucial for releasing signaling molecules like hormones and neurotransmitters.
- Previous electron microscopy studies suggested DCVs have a clear halo surrounding a dense core.
Purpose of the Study:
- To investigate the ultrastructure of DCVs using cryofixation electron microscopy.
- To determine if DCVs contain intraluminal vesicles, such as exosomes.
Main Methods:
- Cryofixation electron microscopy of adrenal chromaffin cells.
- Immunolabeling for dense-core matrix protein chromogranin A (CGA).
- Colocalization studies using fluorescent false neurotransmitter FFN 511 and exosome markers CD63/ALIX.
Main Results:
- Cryofixation revealed dense cores filling entire DCVs, without halos, indicating fixation artifacts in prior studies.
- A fraction of DCVs contained smaller clear-core vesicles (36-168 nm).
- DCVs colocalized with exosome markers (CD63, ALIX), suggesting DCVs contain exosomes.
Conclusions:
- The clear halo observed in chemically fixed DCVs is likely an artifact.
- Dense-core vesicles (DCVs) serve as a novel source for exosome release.
- Exosome release via DCV fusion may contribute to intercellular communication in various physiological processes.
Related Concept Videos
01:33Overview of Secretory Vesicles
8.4K
Secretory vesicles, also known as dense core vesicles (DCVs), are membrane-bound vesicles that transport secretory proteins, such as hormones or neurotransmitters. Regulated secretory vesicles transport proteins from the trans-Golgi network to the exterior of the cell. Proteins present in regulated secretory vesicles are required to be rapidly exocytosed in large amounts upon a specific stimulus.
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
8.4K
01:36Overview of Exosomes
2.7K
Exosomes are stable, lipid bilayer-enclosed vesicles capable of crossing biological barriers. They can carry a wide range of molecules required for intercellular communication. Once exosomes are released from the cell where they originated, they enter a recipient cell through various pathways such as fusion, receptor-mediated endocytosis, macropinocytosis, and phagocytosis.
Stahl et al. discovered exosomes in 1983, but the exosomes were initially considered waste products released from the...
Stahl et al. discovered exosomes in 1983, but the exosomes were initially considered waste products released from the...
2.7K
00:50Exocytosis
6.5K
Exocytosis is a process that releases molecules outside the cell. Like other bulk transport mechanisms, exocytosis requires energy.
Exocytosis is the opposite of endocytosis, which brings molecules inside the cell. Sometimes, the released materials are signaling molecules. For example, neurons typically use exocytosis to release neurotransmitters. Cells also use exocytosis to insert proteins such as ion channels into their cell membranes, secrete proteins for use in the extracellular matrix, or...
Exocytosis is the opposite of endocytosis, which brings molecules inside the cell. Sometimes, the released materials are signaling molecules. For example, neurons typically use exocytosis to release neurotransmitters. Cells also use exocytosis to insert proteins such as ion channels into their cell membranes, secrete proteins for use in the extracellular matrix, or...
6.5K
01:26Fusion of Secretory Vesicles with the Plasma Membrane
10.9K
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
10.9K
01:05Insulin Secretory Vesicles
4.8K
Insulin secretory vesicles release insulin to stimulate blood glucose uptake and regulate carbohydrate metabolism. When the blood glucose levels increase, glucose enters the pancreatic β-islet cells through glucose transporters. Once inside, glucose is metabolized through glycolysis, the citric acid cycle, and the electron transport chain, producing ATP. This increase in ATP concentration closes ATP-sensitive potassium channels, leading to depolarization of the membrane and the opening of...
4.8K
01:38Intralumenal Vesicles and Multivesicular Bodies
3.4K
Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
3.4K