| 1998 |
VTI1A (Vti1-rp2) is a 29-kDa integral membrane SNARE protein enriched in the Golgi membrane. It binds alpha-SNAP (retained on GST-alpha-SNAP affinity resin from Golgi extracts), co-immunoprecipitates with syntaxin 5 and syntaxin 6, indicating participation in at least two distinct Golgi SNARE complexes. Antibody microinjection against Vti1-rp2 arrested VSV-G protein transport at the Golgi, establishing a functional role in the secretory pathway. |
Subcellular fractionation, indirect immunofluorescence, GST-alpha-SNAP pulldown, co-immunoprecipitation, antibody microinjection with VSV-G trafficking assay |
The Journal of biological chemistry |
High |
9705316
|
| 2000 |
A brain-specific splice variant, Vti1a-beta (with a 7-amino-acid insertion near the SNARE-interacting helix), is enriched in small synaptic vesicles and clathrin-coated vesicles from nerve terminals. It co-purifies with synaptobrevin during immunoisolation of synaptic vesicles and forms a distinct SNARE complex that binds NSF and alpha-SNAP but does not co-immunoprecipitate with syntaxin 1 or SNAP-25, indicating it functions in a recycling/biogenesis step rather than exocytosis. |
Subcellular fractionation, immunoisolation of synaptic vesicles, co-immunoprecipitation, SDS-PAGE/immunoblot |
The Journal of neuroscience |
High |
10908612
|
| 2005 |
Vti1a is a component of insulin-sensitive GLUT4-containing vesicles in 3T3-L1 adipocytes (identified by mass spectrometry in purified GLUT4 membranes). Insulin treatment depletes Vti1a from these membranes. siRNA-mediated knockdown of Vti1a significantly inhibited both adiponectin (Acrp30) secretion and insulin-stimulated glucose uptake, establishing Vti1a as a regulator of a common trafficking step for GLUT4 and Acrp30. |
Proteomics/mass spectrometry of purified vesicles, siRNA knockdown, deoxyglucose uptake assay, secretion assay, immunofluorescence colocalization |
The Journal of biological chemistry |
Medium |
16131485
|
| 2009 |
Vti1a co-localizes with VAMP7 on KChIP1-expressing intracellular vesicles in HeLa and Neuro2A cells. siRNA knockdown of either Vti1a or VAMP7 inhibited Kv4/KChIP1 traffic to the plasma membrane but had no effect on conventional VSVG traffic or KChIP2-stimulated Kv4.2 traffic, defining a VAMP7/Vti1a-containing SNARE complex that mediates a non-conventional trafficking route to the cell surface. |
siRNA knockdown, immunofluorescence colocalization, cell-surface trafficking assay |
The Biochemical journal |
Medium |
19138172
|
| 2011 |
Double knockout of vti1a and vti1b in mice results in perinatal lethality with major axon tract defects and >95% neuron loss in dorsal root and geniculate ganglia at E18.5, while single knockouts are viable without these defects. Fibroblasts lacking both SNAREs survive with intact organelle morphology and minor trafficking defects, indicating that more distantly related SNAREs can substitute in endosomal traffic in non-neuronal cells but not in neurons. |
Genetic knockout (double and single null mice), histology, immunofluorescence, cell viability assays in fibroblasts |
Proceedings of the National Academy of Sciences of the United States of America |
High |
21262811
|
| 2011 |
A VTI1A-TCF7L2 in-frame gene fusion is found in 3/97 colorectal cancers. The fusion protein lacks the TCF4 β-catenin-binding domain. The colorectal carcinoma cell line NCI-H508 harboring the fusion is dependent on VTI1A-TCF7L2 for anchorage-independent growth, as demonstrated by RNAi-mediated knockdown. |
Whole-genome sequencing, RNAi knockdown, anchorage-independent growth assay |
Nature genetics |
Medium |
21892161
|
| 2012 |
Vti1a marks a synaptic vesicle pool that recycles preferentially under resting conditions and selectively maintains high-frequency spontaneous neurotransmitter release. Loss of vti1a function specifically reduced spontaneous miniature release detected postsynaptically. Expression of a truncated vti1a augmented spontaneous release more than full-length vti1a, indicating an autoinhibitory mechanism regulates vti1a function. |
Multicolor live imaging at individual synapses, loss-of-function (dominant-negative truncation), electrophysiological recordings (mEPSC/mIPSC frequency) |
Neuron |
High |
22243751
|
| 2014 |
Vti1a is absent from mature dense-core vesicles (DCVs) in adrenal chromaffin cells but localizes near the trans-Golgi network (partially overlapping with syntaxin-6). Vti1a null cells have fewer and smaller DCVs with reduced synaptobrevin-2 content and fewer Ca2+-channels at the plasma membrane, impairing exocytosis. Release kinetics and Ca2+-sensitivity are unchanged. Long-term (days) but not short-term (hours) re-expression restores secretion, placing vti1a function in an upstream vesicle biogenesis/generation step rather than in the final fusion reaction. Additional deletion of vti1b did not exacerbate the phenotype; vti1b null cells showed no secretion defects. |
Immunofluorescence/localization, null mouse chromaffin cells, carbon-fiber amperometry, Ca2+ imaging, electron microscopy, rescue by long-term vs. short-term re-expression |
The EMBO journal |
High |
24902738
|
| 2018 |
Vti1a/b-deficient neurons show severely impaired synaptic vesicle and dense-core vesicle secretion. Synaptic levels of SNAP-25 are reduced to ~50%, and both SNAP-25 and DCV cargo accumulate in the Golgi. Cargo exits the Golgi less efficiently but enters normally. Retrograde cholera toxin trafficking is compromised while Sortilin/Sorcs1 distribution is unaffected. Either Vti1a or Vti1b expression alone rescues these defects. Distended Golgi cisternae and vacuoles are observed. Conclusion: Vti1a/b support regulated secretion by sorting secretory cargo and secretion machinery at the Golgi. |
Vti1a/b double KO neurons, live-cell imaging of cargo trafficking, immunofluorescence, electrophysiology (SV secretion), electron microscopy |
Nature communications |
High |
30143604
|
| 2018 |
The VTI1A-TCF4 fusion protein acts as a dominant-negative regulator of Wnt signaling: NCI-H508 cells carrying the fusion show no active Wnt signaling, and overexpression of the fusion in LS174T cells inhibits a Wnt signaling luciferase reporter. The VTI1A promoter is highly active in colon cancer cells and is transcriptionally activated by the intestinal homeodomain factor CDX2. |
Luciferase reporter assay (Wnt signaling), overexpression in colon cancer cell lines, promoter-reporter assay, CDX2 transcription factor assay |
PloS one |
Medium |
29975781
|
| 2021 |
Synaptotagmin-11 (Syt11) directly interacts with vti1a and suppresses spontaneous neurotransmission through it. GST pulldown, co-immunoprecipitation, and affinity purification demonstrated direct Syt11–vti1a interaction. The C2A domain of Syt11 binds vti1a with high affinity. Knockdown of vti1a reversed the elevated spontaneous release phenotype of Syt11 knockout neurons, placing vti1a downstream of Syt11 inhibition. |
GST pulldown, co-immunoprecipitation, affinity purification, domain deletion analysis, siRNA knockdown of vti1a in Syt11 KO neurons, electrophysiology (mEPSC frequency) |
Journal of neurochemistry |
High |
34599505
|
| 2021 |
Vti1a and Vti1b are required for cortical development: their double null mutation depletes neural progenitor pools and causes distinctive disorganization of cortical layer 5, with apoptosis of Ctip2-expressing L5 neurons and loss of corticospinal and callosal projections. |
Vti1a/b double null mouse, histology, immunofluorescence, apoptosis assays |
Neuroscience |
Medium |
33774122
|
| 2022 |
In the absence of vti1a and vti1b, hippocampal neurons lack Golgi outposts in dendrites and cortical neurons have significantly shorter neurites. Neurite elongation stimulated by neurotrophic factors (NGF, BDNF, NT-3, GDNF) or ROCK inhibitor Y27632 (enlargeosome exocytosis) is abolished in double-deficient neurons. vti1a or vti1b functions as the Qb-SNARE in a complex with VAMP-4 (R-SNARE), syntaxin 16 (Qa-SNARE), and syntaxin 6 (Qc-SNARE) required for induced neurite outgrowth. |
Double KO primary neurons (hippocampal and cortical), immunofluorescence for Golgi outposts, neurite length measurement, neurotrophic factor/Y27632 stimulation, Western blotting of postsynaptic densities |
Neural development |
Medium |
36419086
|
| 2022 |
In Vti1a/b-deficient neurons, the cis-/medial Golgi (GM130, giantin staining) is increased while TGN recycling proteins TGN38 and TMEM87A are decreased, without overall reduction in Golgi size or absence of TGN compartment. DCV cargo markers and LAMP1/KDEL distribution are altered. Cholera Toxin retrograde trafficking is disrupted. Partial phenocopy is achieved by disturbing sphingolipid homeostasis, but overexpression of sphingomyelin synthases or myriocin treatment does not rescue, indicating that Vti1a/b are required for distinct aspects of TGN and cis-/medial Golgi organization beyond sphingolipid regulation. |
Vti1a/b double KO neurons, immunofluorescence for Golgi markers, live retrograde trafficking assay (Cholera Toxin), sphingolipid pathway perturbation |
Scientific reports |
Medium |
36460703
|
| 2024 |
CRISPR/Cas9-generated Vti1a/Vti1b double knockout in N1E-115 neuroblastoma cells impairs differentiation, reduces synaptic protein levels, and reduces neurite formation and elongation. Y27632 (enlargeosome exocytosis via Rho kinase inhibition) fails to stimulate neurite elongation in DKO cells, and Akt signaling during enlargeosome-mediated outgrowth is disrupted. BDNF-induced neurite outgrowth is also impaired, with disrupted Erk signaling, placing vti1a/b upstream of these growth factor signaling cascades. |
CRISPR/Cas9 double KO, neurite length measurement, Western blotting (Akt, Erk phosphorylation), neurotrophic factor stimulation assays |
European journal of cell biology |
Medium |
39406055
|