Activity-dependent release of phosphorylated human tau from Drosophila neurons in primary culture

Ismael, Sazan; Colvin, Robert A.; Lee, Daewoo

doi:10.1016/j.jbc.2021.101108

Cited by 7 publications

(13 citation statements)

References 59 publications

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“…By TIRF microscopy, we observed a depletion of Tau in the cytoplasm upon the fusion of VAMP8-positive vesicles with the plasma membrane (Pilliod et al, 2020). Other proteins involved in the endocytic pathways such as Bin1 and the two SNAREs, syntaxins 6 and 8 also contribute to Tau secretion (Glennon et al, 2020;Lee et al, 2021). It seems possible that each of these pathways could permit the release of a specific set of Tau forms.…”

Section: Discussionmentioning

confidence: 87%

“…Interestingly, polymorphisms associated with Bin1 is the second largest genetic risk for sporadic AD (Lambert et al, 2013;Vardarajan et al, 2015). Syntaxins 6 and 8, two SNAREs that play an important role in the membranes trafficking, can interact with Tau C-terminal and increase its secretion (Lee et al, 2021). Syntaxin 6 is found at the trans-Golgi network and early endosomes whereas syntaxin 8 is localized on recycling and late endosomes (Jung et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…The presence of Tau in the interstitial fluid in the absence of neurodegeneration was detected by microdialysis in Tau transgenic mouse brain ( Yamada et al, 2011 ). The release of Tau by neurons was shown to be increased by neuronal activity both in vitro and in vivo ( Pooler et al, 2013 ; Yamada et al, 2014 ; Ismael et al, 2021 ). AD is linked to autophagic and lysosomal dysfunction, which was shown to increase the release of Tau by primary cortical neurons ( Mohamed et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

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Unconventional secretion of tau by VAMP8 impacts its intra- and extracellular cleavage

Pilliod

Gélinas-Faucher

Leclerc

2022

Front. Cell Dev. Biol.

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In Alzheimer’s disease, Tau, a microtubule-associated protein, becomes hyperphosphorylated, detaches from microtubules, and accumulates in the somato-dendritic compartment where it forms insoluble aggregates. Tau also accumulates in the CSF of patients indicating that it is released by neurons. Consistent with this, several laboratories including ours have shown that Tau is secreted by neurons through unconventional secretory pathways. Recently, we reported that VAMP8, an R-SNARE found on late endosomes, increased Tau secretion and that secreted Tau was cleaved at the C-terminal. In the present study, we examined whether the increase of Tau secretion by VAMP8 affected its intra- and extracellular cleavage. Upon VAMP8 overexpression, an increase of Tau cleaved by caspase-3 in the cell lysate and medium was observed. This was correlated to an increase of active caspase-3 in the cell lysate and medium. Using a Tau mutant not cleavable by caspase-3, we demonstrated that Tau cleavage by caspase-3 was not necessary for its secretion upon VAMP8 overexpression. By adding recombinant Tau to the culture medium, we demonstrated that extracellular Tau cleavage by caspase-3 could occur because of the release of active caspase-3, which was the highest when VAMP8 was overexpressed. When cleavage of Tau by caspase-3 was prevented by using a non-cleavable mutant, secreted Tau was still cleaved at the C-terminal, the asparagine N410 contributing to it. Lastly, we demonstrated that N-terminal of Tau regulated the secretion pattern of a Tau fragment containing the microtubule-binding domain and the C-terminal of Tau upon VAMP8 overexpression. Collectively, the above observations indicate that VAMP8 overexpression affects the intra- and extracellular cleavage pattern of Tau.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unconventional secretion of tau by VAMP8 impacts its intra- and extracellular cleavage

Pilliod

Gélinas-Faucher

Leclerc

2022

Front. Cell Dev. Biol.

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“…Extracellular activity was measured in control and L435F hCSs at baseline, and the L435F hCSs showed significantly reduced activity ( Figure 7 B). To promote neuronal activity, hCSs were treated with KCl, as KCl has been shown to depolarize neurons and increase activity ( Ismael et al., 2021 ). After treatment with KCl, we found the L435F hCSs continued to show reduced levels of extracellular activity ( Figure 7 B).…”

Section: Resultsmentioning

confidence: 99%

Familial Alzheimer’s disease-associated PSEN1 mutations affect neurodevelopment through increased Notch signaling

et al. 2023

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“…Consistent with our results, it has been demonstrated that intracellular tau was phosphorylated at AT270 (T181), AT100, and PHF-1 in Hela cells (Plouffe et al, 2012). In addition, our recent findings showed that AT8 and AT180 pSites were less phosphorylated inside the cell in Drosophila primary neuronal culture (Ismael et al, 2021). However, Plouffe et al (2012) claimed that intracellular tau at AT8 and AT180 sites was phosphorylated.…”

Section: Discussionmentioning

confidence: 98%

Endogenous tau released from humanReNCell VMcultures by neuronal activity is phosphorylated at multiple sites

Sindi,

Ismael,

Uddin

et al. 2024

Preprint

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Tau is an intracellular protein but also known to be released into the extracellular fluid. Tau release mechanisms have drawn intense attention as these are known to play a key role in Alzheimer’s disease (AD) pathology. However, tau can also be released under physiological conditions although its physiological function and release mechanisms have been poorly characterized, especially in human neuronal cells.We investigated endogenous tau release inReNCellVM, a human neuroprogenitor cell line, under physiological conditions and found that tau is spontaneously released from cells. To study activity-dependent release of endogenous tau, humanReNCell VMculture was stimulated by 100μM AMPA or 50mM KCl for one-hour, tau was actively released to the culture medium. The released tau was highly phosphorylated at nine phosphorylation sites (pSites) detected by phospho-specific tau antibodies including AT270 (T175/T181), AT8 (S202/T205), AT100 (T212/S214), AT180 (T231), and PHF-1 (S396/S404), showing that these pSites are important for activity-dependent tau release from humanReNCellVM. Intracellular tau showed various phosphorylation status across these sites, with AT270 and PHF-1 highly phosphorylated while AT8 and AT180 were minimally phosphorylated, suggesting that AT8 and AT180 pSites exhibit a propensity for secretion rather than being retained intracellularly. This activity-dependent tau release was significantly decreased by inhibition of GSK-3β, demonstrating that GSK3β-dependent phosphorylation of tau plays an important role in its release by neuronal activity.In this study, we showed thatReNCellVM serves as a valuable model for studying endogenous physiological tau release. Further,ReNCellmodel can be also used to study pathological release of human tau that will contribute to our understanding of the progression of AD and related dementias.HighlightsActivity-dependent release of endogenous human tau from human ReNCell VM cultures occurs under physiological conditions.Released human tau is phosphorylated at nine sites (pSites) in the proline-rich domain and the C-terminal domain detected by AT270 (T175/T181), AT8 (S202/T205), AT100 (T212/S214), AT180 (T231), and PHF-1 (S396/S404) tau antibodies, strongly suggesting that these pSites are important for activity-dependent tau release from human ReNCell VM.In contrast, intracellular human tau proteins have different phosphorylation status among these nine pSites: AT270 and PHF-1 pSites are highly phosphorylated, but AT8 and AT180 are weakly phosphorylated, suggesting AT8 and AT180 pSites are release-sensitive phosphorylation motifs.Activity-dependent release of endogenous human tau is decreased by a tau kinase GSK-3β inhibitor SB 216763, indicating that GSK-3β-dependent phosphorylation plays an important role in activity-dependent tau release.The humanReNCellculture is an excellent model system to study mechanisms underlying physiological release of endogenous tau.

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Activity-dependent release of phosphorylated human tau from Drosophila neurons in primary culture

Cited by 7 publications

References 59 publications

Unconventional secretion of tau by VAMP8 impacts its intra- and extracellular cleavage

Unconventional secretion of tau by VAMP8 impacts its intra- and extracellular cleavage

Familial Alzheimer’s disease-associated PSEN1 mutations affect neurodevelopment through increased Notch signaling

Endogenous tau released from humanReNCell VMcultures by neuronal activity is phosphorylated at multiple sites

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