Related Experiment Video
Updated: May 28, 2026
09:00
Live Cell Imaging of Early Autophagy Events: Omegasomes and Beyond
Published on: July 27, 2013
Autophagosome biogenesis requires SNAREs
1Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
Autophagy
|October 26, 2011
Summary
Autophagosome biogenesis requires SNARE proteins for vesicle fusion. Specific SNAREs (Sso1/2, Sec9, Tlg2, Sec22, Ykt6) mediate early steps in phagophore assembly and Atg9 trafficking.
Area of Science:
- Cell Biology
- Molecular Biology
Background:
- Autophagosome biogenesis is crucial for cellular homeostasis.
- Phagophore assembly, the initial step, involves complex membrane dynamics.
- The role of SNARE proteins in autophagosome formation is not fully understood.
Purpose of the Study:
- To investigate the role of SNARE proteins in the early stages of autophagosome biogenesis.
- To identify specific SNAREs involved in Atg9 vesicle trafficking and fusion.
Main Methods:
- Genetic analysis of SNARE mutants in yeast.
- Immunofluorescence microscopy to track Atg9 localization.
- Co-immunoprecipitation assays to study protein interactions.
Main Results:
- Exocytic Q/t-SNAREs Sso1/2 and Sec9 are essential for the homotypic fusion of Atg9-containing vesicles.
- This fusion event is proposed to precede the formation of Atg9-containing tubulovesicular clusters (TVCs).
- Endosomal Tlg2 and R/v-SNAREs Sec22 and Ykt6 interact with Sso1-Sec9 and are vital for Atg9 trafficking.
Conclusions:
- Autophagosome biogenesis involves multiple SNARE-mediated membrane fusion events.
- SNAREs play critical roles in regulating the early steps of phagophore assembly.
- These findings offer new insights into the molecular mechanisms underlying autophagosome formation.
Related Concept Videos
01:43SNAREs and Membrane Fusion
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
01:27Autophagy
Autophagy is a self-digesting process by which a cell protects itself from threats both within and outside the cell, ranging from abnormal proteins to invading bacteria. In this process, obsolete components of the cell and invading microbes are degraded by hydrolytic enzymes active in an acidic environment of the lysosomal lumen.
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
An autophagic pathway consists of a series of signaling events activated in response to diverse stress and physiological conditions such as food deprivation,...
01:36Delivery Pathways to the Lysosome
Eukaryotic cells use different mechanisms to eliminate toxic waste obsolete and worn-out substances. Lysosomes play a pivotal role in this, and hence, these substances are carried to the lysosome from other parts of the cell and extracellular space through different pathways. The most elaborately studied pathways to the lysosome are the endocytic pathways.
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...
Endocytosis
In endocytosis, the cell membrane takes up macromolecules and particles from the surrounding medium. Clathrin-mediated...
01:12Clathrin Coated Vesicles
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
01:38Intralumenal Vesicles and Multivesicular Bodies
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...
01:25Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.