a(HBP:"Tau epitope, PHF1")

Entity

Name

Tau epitope, PHF1

Namespace

HBP

Namespace Version

20181119

Namespace URL

https://raw.githubusercontent.com/pharmacome/terminology/90e1cb9e5e882703380c9db8d4915ac6f3cba137/export/hbp-names.belns

Activating autophagy with trehalose in rat cortical neurons demonstrated certain phospho-epitopes (AT8, PHF1, and 12E8) were reduced more significantly than total tau – up to 80% compared to the 20% reduction in total tau (96). PubMed:24027553

The PHF-1 epitope (pSer396+pSer404, Fig. 2 D–F) is seen in both types of Tau transgenic slices where it appears in the somatodendritic compartment (asterisks) and in the axonal grains (arrowheads) PubMed:27671637

The PHF-1 epitope (pSer396+pSer404, Fig. 2 D–F) is seen in both types of Tau transgenic slices where it appears in the somatodendritic compartment (asterisks) and in the axonal grains (arrowheads) PubMed:27671637

Significantly, we found similar effects in human dopaminergic neurons (Fig. 2F). Treatment of neurons with L-Dopa induced a 40–49% decrease in methylated PP2A and concomitant 168–179% increase in endogenous p-Tau (PHF-1) levels (Fig. 2G). PubMed:22764226

Consistent with previous reports (11,34), treatment of rat hippocampal neurons with synthetic Aβ, prepared using a well-characterized procedure that enriches for Aβ oligomers (37), resulted in increased tau phosphorylation at the 12E8 sites (Fig. 2A), suggesting that Aβ treatment had activated MARK kinases. Increased phosphorylation of tau at a site recognized by the PHF-1 phospho-tau antibody was also observed (data not shown). PubMed:22156579

Small molecules in the diaminothiazole class are potent Tau kinase inhibitors that target CDK5 and GSK3β. Lead compounds from the series have IC50 values toward CDK5/p25 and GSK3β in the low nanomolar range and no observed toxicity in the therapeutic dose range. Neuronal protective effects and decreased PHF-1 immunoreactivity were observed in two animal models, 3×Tg-AD and CK-p25. Treatment nearly eliminated Sarkosyl-insoluble Tau with the most prominent effect on the phosphorylation at Ser-404. Treatment also induced the recovery of memory in a fear conditioning assay. PubMed:23737518

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

Hence, LTD-inducing NMDA receptor activation leads to an increase in tau phosphorylation at sites PHF-1, AT180, as well as AT8 and to a reduction at AT100. PubMed:22833681

In particular, previous studies have demonstrated that the tau ubiquitin ligase, CHIP, is unable to bind and ubiquitinate tau species phosphorylated by Par-1/MARK2 on the 12E8 epitope (S262/356) [33], a p-tau species that is also resistant to degradation upon treatment with Hsp90 inhibitors [32,33]. Tau phosphorylated at the PHF1 epitope (S396/404) is still susceptible to degradation following Hsp90 inhibition and actually exhibits an enhanced interaction with Hsp90 PubMed:25031639

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

We further validated Syk as a target-regulating Aβ by showing that pharmacological inhibition of Syk or down-regulation of Syk expression reduces Aβ production and increases the clearance of Aβ across the BBB mimicking (-)-nilvadipine effects. Moreover, treatment of transgenic mice overexpressing Aβ and transgenic Tau P301S mice with a selective Syk inhibitor respectively decreased brain Aβ accumulation and Tau hyperphosphorylation at multiple AD relevant epitopes. PubMed:25331948

CRF-OE mice had significantly elevated tau-P compared to wild type (WT) mice at the AT8 (S202/T204), PHF-1 (S396/404), S262, and S422 sites. Treating CRF-OE mice with R121919 blocked phosphorylation at the AT8 (S202/T204) and PHF-1 (S396/404) sites, but not at the S262 and S422 sites and reduced phosphorylation of c-Jun N Terminal Kinase (JNK). PubMed:25125464

CRF-OE mice had significantly elevated tau-P compared to wild type (WT) mice at the AT8 (S202/T204), PHF-1 (S396/404), S262, and S422 sites. Treating CRF-OE mice with R121919 blocked phosphorylation at the AT8 (S202/T204) and PHF-1 (S396/404) sites, but not at the S262 and S422 sites and reduced phosphorylation of c-Jun N Terminal Kinase (JNK). PubMed:25125464

Reductions in PP2A methylation were associated with a concomitant increase in each brain region of p-Tau at the PHF-1 epitope (Fig. 6A,B). PubMed:22764226

The PHF-1 epitope (pSer396+pSer404, Fig. 2 D–F) is seen in both types of Tau transgenic slices where it appears in the somatodendritic compartment (asterisks) and in the axonal grains (arrowheads) PubMed:27671637

The PHF-1 epitope (pSer396+pSer404, Fig. 2 D–F) is seen in both types of Tau transgenic slices where it appears in the somatodendritic compartment (asterisks) and in the axonal grains (arrowheads) PubMed:27671637

Reductions in PP2A methylation were associated with a concomitant increase in each brain region of p-Tau at the PHF-1 epitope (Fig. 6A,B). PubMed:22764226

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

We first confirmed that expression of an MKI-GFP fusion protein in rat hippocampal neurons effectively attenuated MARK4-mediated phosphorylation of both endogenous tau (Fig. 3A) and transfected human tau at the 12E8 sites (Fig. 3B). Phosphorylation of tau at the PHF-1 site was also reduced by MKI (Fig. 3A). It is possible that the PHF-1 site is also targeted by PAR-1/MARKs in vivo, or that the phosphorylation of tau at the 12E8 sites is a prerequisite for PHF-1 site phosphorylation, as the 12E8 sites were previously shown to be required for tau phosphorylation at other sites PubMed:22156579

CRF-OE mice had significantly elevated tau-P compared to wild type (WT) mice at the AT8 (S202/T204), PHF-1 (S396/404), S262, and S422 sites. Treating CRF-OE mice with R121919 blocked phosphorylation at the AT8 (S202/T204) and PHF-1 (S396/404) sites, but not at the S262 and S422 sites and reduced phosphorylation of c-Jun N Terminal Kinase (JNK). PubMed:25125464

Because S199/S202/T205E, S396/S404E, 6-Phos and 7-Phos all demonstrated an AD-like shift in mobility as a result of phosphorylation-like changes, we conclude that they have the characteristics of hyperphosphorylated tau. These mutants will therefore be referred to as pseudo-hyperphosphorylated tau throughout the manuscript. On the basis of the observations that pseudohyperphosphorylated tau has decreased affinity for microtubules and reduced inducer-initiated rates of nucleation and polymerization, we propose that this combination could be the cause of the increased cytotoxicity of hyperphosphorylated tau in Alzheimer's disease and also explain the potentially beneficial role of tau polymerization and NFT formation. PubMed:19459590

In particular, previous studies have demonstrated that the tau ubiquitin ligase, CHIP, is unable to bind and ubiquitinate tau species phosphorylated by Par-1/MARK2 on the 12E8 epitope (S262/356) [33], a p-tau species that is also resistant to degradation upon treatment with Hsp90 inhibitors [32,33]. Tau phosphorylated at the PHF1 epitope (S396/404) is still susceptible to degradation following Hsp90 inhibition and actually exhibits an enhanced interaction with Hsp90 PubMed:25031639

Consistent with previous reports (11,34), treatment of rat hippocampal neurons with synthetic Aβ, prepared using a well-characterized procedure that enriches for Aβ oligomers (37), resulted in increased tau phosphorylation at the 12E8 sites (Fig. 2A), suggesting that Aβ treatment had activated MARK kinases. Increased phosphorylation of tau at a site recognized by the PHF-1 phospho-tau antibody was also observed (data not shown). PubMed:22156579