Alzheimer's Disease and Tau-1

8/9/2019 Alzheimer's Disease and Tau-1

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Association Of Phosphorylation Site Of Tau Protein With

Neuronal Apoptosis In Alzheimer’s Disease.

Katsuji Kobayashia

, Hiroyuki Nakanoa, asahiro Hayashi!, asao Shimazakia,"uken #ukutanic, $azuo

Sasakic, $aoru Su%imoria, "oshifumi $oshinoa

Journal of the Neurological Sciences &'(()* '(+ -. '/

Presented by: Abhirama B Sarepaka N0241092

MSc Pharmacology


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Apoptosis, a programmed cell death by intrinsic mechanism to regulate cellpopulation

Apoptosis occurs extensively in brains from patients with Alzheimer’s disease(AD).

athological !allmar" of AD# neuro$brillary tangles (%&') and βamyloidprotein (A) deposits, abundant apoptotic neuronal and glial cells.

'riggers for neuronal and glial apoptosis# Abnormal phosphorylation of the tauprotein leading to %&' formation, A deposits, high concentration of amyloidprecursor protein (A), caspase*, the presenilin + and genes and %-.

ince %&' are present in the neuronal cytoplasm, %&' and neuronal apoptosishave been considered to be intimately associated with each other.

+* studies, +/ in vivo and * in vitro have addressed the relationship between%&' formation and neuronal apoptosis.

!owever, it is still unclear whether neuronal apoptosis is a result or cause ofabnormal phosphorylation of tau.

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'au immunohistochemistry has di0erentiated pretangle neurons,

"nown as stage / tangles.

hosphorylation sites of the amino acid se1uence of tau moleculeshave been analyzed in AD brains.

'he pretangle neurons are believed to occur in the early stage andmay disappear in the late stage of AD with some of them remainingunchanged.

'he tau protein is 22+amino acid long and ADassociated abnormal

phosphorylation of the tau protein occurs at serine /. 'he antibody

A'3 binds to phosphorylation site //4.

-ther phosphorylation sites of tau protein are *+ detectable by

A'+3/, 546+/3 detectable by 'au, and +456+7* detectable by !'8.

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rains used# 8 patients of AD, 8 9ontrol.

'he postmortem delay ranged from *./ to 3.2 h (average *.8 h).

'he brains removed at autopsy $xed with +/: formalin, and cut intoslices coronally and embedded in para;n wax.


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Di0erent phosphorylated tau proteins labelled using $ve monoclonal antiseraA'3, A'+3/, !'8, and 'au and 'au 4.

Amyloid deposits labeled using monoclonal antiA antiserum (clone 2?3).

ections for 'd' mediated @' %ic"nd =abeling ('@%=) $rst treated withproteinase B (/ AgCml for min r.t.), and the endogenous peroxidase

activity 1uenched.

Eor"ing strength 'd' enzyme mixture pipetted onto slidemounted tissuesections and incubated for + h at *8/.

Double immunolabeling of the abovementioned antitau antisera and '@%=positive nuclei was performed to con$rm the colocalization of the apoptoticnuclei and taupositive neurons in several sections.

'he materials stained during '@%= turned dar" blue and those during the taulabeling brown. rain sections also stained with the ?allyas silve5


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Double labeling of A'3 and '@%= of the frontal cortex (2//). A'3positive tangleli"estructures (!lack arro0s) are seen in the neuronal cytoplasm with '@%=stained nuclei. A

'@%=stained nucleus without A'3positive structure is indicated with the 1e2 arro03 &!Double labeling of A'+3/ and '@%= of the 9A (2//). &c* Double labeling of !'8 and '@%= othe cingulate cortex (8/). !'8positive and '@%=stained neurons (!lack arro0s) show


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>n the AD brains, there was no statistical di0erence in density of neurons positivefor $ve antitau antisera, ?allyas stained %&' and '@%=positive neuronal nuclei

among the AD cases examined.

'here was no statistical correlation in density between '@%=stained neurons andtaupositive or ?allyas stained %&' in the cingulate gyrus, entorhinal cortex orparietal cortex.

'he ratio of neurons labeled with each of the antitau antisera to the '@%=labeled nuclei was 7.4: for A'+3/, 3.5: for A'3, *7.5: for !'8, 3+.: for

'au, 2/.8: for 'au4 and .3: for ?allyas techni1ue.

9orrelation analysis of the seven regions showed an inverse correlation betweenthe density of '@%=stained neurons and that of A'3positive and ?allyasstained

%&' in the 9A as well as that of A'+3/positive neurons in the temporal neocortex.

>n contrast, '@%= stained neuronal density correlated positively with the densityof A'3positive neurons, !'8 and 'au4 in the frontal neocortex and 'au4 in theoccipital cortex

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ostmortem delay in AD cases, ranged from *./ to 3.2 h, was found to ma"eonly a minor contribution to an increase in apoptotic cells.


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A'3positive neurons with '@%=unstained normal nuclei observed. !ence

the presence of such cells implies that the apoptotic process follows theinitial phosphorylation but also that the apoptotic process may be reversible

'he density of neurons positive for antitau antisera other than 'augenerally indicated a predominant density of '@%=stained nuclei.

'his evidence suggests that abnormal phosphorylation of tau proteinprecedes apoptotic nuclear change.

Amyloid $bril formation has been shown to be one factor associated with tauprotein phosphorylation in AD, and early tau deposition is regulated by

phosphorylated IA "inase .

Apoptosis is essentially an intrinsic mechanism, so that factors merelyaccelerate or recover the process

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ST14N5THS6 DI4 $1A#T 'he topic for investigation is aptubHects for xperiments ar

'he result follows the experiment that apoptotic change follows phosphorytudy con$rmed the presence of '@%=labelled nuclei in taulabelledneurons.W4A$N4SS4S6D47O84SSA

'he points under investigation are too many%ot enough data for any statistical analysi

>n the AD brains, there was no statistical di0erence in density of neuronspositive for $ve antitau antisera, ?allyas stained %&' and '@%=positiveneuronal nuclei among the AD cases examined.

'here was no statistical correlation in density between '@%=stained neuronsand taupositive or ?allyas stained %&'.

9-%9=@>-%Apoptosis de$ned as '@%= positivity can occur in pretangle neurons,and regional di0erences in density of both '@%=stained and taulabeled neurons may constitute supportive evidence for the occurrenceof apoptosis at the pretangle neuron stage


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mployment of 9AA* and other relatedapoptotic related for the early identi$cationof hyperphosphorylation sites of 'au proteins.

&urther research can be underta"en regardingthe interaction of '@%= staining and Anitauantibodies for the early detection andpossibly cure of Alzheimer’s Disease.

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J+K u L!, Anderson LA, 9ummings L, 9otman 9E. >mmunohistochemical evidence of apoptosis in Alzheimer’s

disease. %euroreport +552M4#456 **.JK 9otman 9E, Anderson AL. A potential role for apoptosis in neurodegeneration and Alzheimer’s disease. Io

%eurobiol +554M+/#+/ 6 24.

J*K =assmann !, ancher 9, reitschopf !, Eegiel L, obins"i I, Lellinger BA, et al. 9ell death in Alzheimer’sdisease evaluated by D%A fragmentation in situ. Acta %europathol (erl) +554M35#*46 2+.

J2K 9otman 9E, u L!. Iechanisms of neuronal death in Alzheimer’s disease. rain athol +557M7#25* 6 4/7.

J4K male ?, %ichols %


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Alzheimer's Disease and Tau-1