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Mechanistic Studies of Antibody-Mediated Clearance of Tau Aggregates Using an ex vivo Brain Slice Model.

Krishnamurthy PK, Deng Y, Sigurdsson EM - Front Psychiatry (2011)

Bottom Line: Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies.Additionally, tau and FITC-IgG were found together in an enriched lysosome fraction.In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Neuroscience, New York University School of Medicine New York, NY, USA.

ABSTRACT
Recent studies have shown that immunotherapy clears amyloid beta (Aβ) plaques and reduces Aβ levels in mouse models of Alzheimer's disease (AD), as well as in AD patients. Tangle pathology is also relevant for the neurodegeneration in AD, and our studies have shown that active immunization with an AD related phospho-tau peptide reduces aggregated tau within the brain and slows the progression of tauopathy-induced behavioral impairments. Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies. So far the mechanisms involved in antibody-mediated clearance of tau pathology are yet to be elucidated. In this study we have used a mouse brain slice model to examine the uptake and localization of FITC labeled anti-tau antibodies. Confocal microscopy analysis showed that the FITC labeled anti-tau antibody co-stained with phosphorylated tau, had a perinuclear appearance and co-localized with markers of the endosomal/lysosomal pathway. Additionally, tau and FITC-IgG were found together in an enriched lysosome fraction. In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.

No MeSH data available.


Related in: MedlinePlus

Non-immunized JNPL3 mice have more lysosomes than WT mice and these contain tau. Brain slices (400 μm) were processed to obtain an enriched lysosome fraction. (A) Representative immunoblot showing the presence of lysosomes (LAMP2) and tau (DAKO A0024) was confirmed in fractions from both WT and JNPL3 mice. Mouse kidney lysate was used as a positive control. (B) Quantification of immunoblots indicated that non-immunized JNPL3 mice had fourfold more lysosomes than WT mice, with corresponding eightfold higher amounts of tau (n = 3 separate experiments).
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Figure 4: Non-immunized JNPL3 mice have more lysosomes than WT mice and these contain tau. Brain slices (400 μm) were processed to obtain an enriched lysosome fraction. (A) Representative immunoblot showing the presence of lysosomes (LAMP2) and tau (DAKO A0024) was confirmed in fractions from both WT and JNPL3 mice. Mouse kidney lysate was used as a positive control. (B) Quantification of immunoblots indicated that non-immunized JNPL3 mice had fourfold more lysosomes than WT mice, with corresponding eightfold higher amounts of tau (n = 3 separate experiments).

Mentions: JNPL3 mice overexpress mutant tau (P301L) and develop extensive tau pathology (Lewis et al., 2000). A potential route involved in the clearance of pathological tau is the endosomal–lysosomal pathway, hence we next examined if markers of the lysosomal pathway were upregulated in these animals. Enriched lysosome fractions were prepared from wild type and JNPL3 brain slices. The presence of lysosomes was confirmed in LAMP2 positive fractions from both wild type and JNPL3 mice (Figure 4). The transgenic mice appeared to have more lysosomes than wild type mice. Additionally, immunoblotting of lysosome fractions with the total tau antibody showed the presence of tau in both wild type and transgenic mice, but as expected lysosomes from the latter group had much more tau than lysosomes obtained from wild type brain (Figure 4).


Mechanistic Studies of Antibody-Mediated Clearance of Tau Aggregates Using an ex vivo Brain Slice Model.

Krishnamurthy PK, Deng Y, Sigurdsson EM - Front Psychiatry (2011)

Non-immunized JNPL3 mice have more lysosomes than WT mice and these contain tau. Brain slices (400 μm) were processed to obtain an enriched lysosome fraction. (A) Representative immunoblot showing the presence of lysosomes (LAMP2) and tau (DAKO A0024) was confirmed in fractions from both WT and JNPL3 mice. Mouse kidney lysate was used as a positive control. (B) Quantification of immunoblots indicated that non-immunized JNPL3 mice had fourfold more lysosomes than WT mice, with corresponding eightfold higher amounts of tau (n = 3 separate experiments).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198029&req=5

Figure 4: Non-immunized JNPL3 mice have more lysosomes than WT mice and these contain tau. Brain slices (400 μm) were processed to obtain an enriched lysosome fraction. (A) Representative immunoblot showing the presence of lysosomes (LAMP2) and tau (DAKO A0024) was confirmed in fractions from both WT and JNPL3 mice. Mouse kidney lysate was used as a positive control. (B) Quantification of immunoblots indicated that non-immunized JNPL3 mice had fourfold more lysosomes than WT mice, with corresponding eightfold higher amounts of tau (n = 3 separate experiments).
Mentions: JNPL3 mice overexpress mutant tau (P301L) and develop extensive tau pathology (Lewis et al., 2000). A potential route involved in the clearance of pathological tau is the endosomal–lysosomal pathway, hence we next examined if markers of the lysosomal pathway were upregulated in these animals. Enriched lysosome fractions were prepared from wild type and JNPL3 brain slices. The presence of lysosomes was confirmed in LAMP2 positive fractions from both wild type and JNPL3 mice (Figure 4). The transgenic mice appeared to have more lysosomes than wild type mice. Additionally, immunoblotting of lysosome fractions with the total tau antibody showed the presence of tau in both wild type and transgenic mice, but as expected lysosomes from the latter group had much more tau than lysosomes obtained from wild type brain (Figure 4).

Bottom Line: Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies.Additionally, tau and FITC-IgG were found together in an enriched lysosome fraction.In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Neuroscience, New York University School of Medicine New York, NY, USA.

ABSTRACT
Recent studies have shown that immunotherapy clears amyloid beta (Aβ) plaques and reduces Aβ levels in mouse models of Alzheimer's disease (AD), as well as in AD patients. Tangle pathology is also relevant for the neurodegeneration in AD, and our studies have shown that active immunization with an AD related phospho-tau peptide reduces aggregated tau within the brain and slows the progression of tauopathy-induced behavioral impairments. Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies. So far the mechanisms involved in antibody-mediated clearance of tau pathology are yet to be elucidated. In this study we have used a mouse brain slice model to examine the uptake and localization of FITC labeled anti-tau antibodies. Confocal microscopy analysis showed that the FITC labeled anti-tau antibody co-stained with phosphorylated tau, had a perinuclear appearance and co-localized with markers of the endosomal/lysosomal pathway. Additionally, tau and FITC-IgG were found together in an enriched lysosome fraction. In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.

No MeSH data available.


Related in: MedlinePlus