[P4-102]: CHARACTERISATION OF MOLECULAR MECHANISMS THAT ARE TRIGGERED AND CONTRIBUTE TO TAU PATHOLOGY IN A CELL MODEL OF TAU AGGREGATION

Tau is a neuron-specific microtubule-binding protein that stabilizes microtubules. It is generally thought that highly phosphorylated tau dissociates from microtubules and becomes insoluble aggregates, leading to neuronal degeneration. Due to the implication of tau aggregation in neurodegenerative disorders, including Alzheimer’s disease, great efforts have been made to identify the tau aggregation process. However, tau interaction with tubulin during the aggregation process remains largely unknown. To scrutinize the tau-tubulin interaction, we generated a cell model that enables visualization of the tau-tubulin interaction in a living cell using the Bifluorescence Complementation (BiFC) Technique. Upon diverse chemical stimulation that induced tau pathology, tau-tubulin BiFC cells showed significantly increased levels of BiFC fluorescence, indicating that tau aggregates together with tubulin. Our results suggest that tubulin should be considered as a key component in the tau aggregation process.

Download Full-text

529. PROPROTEIN CONVERTASE 6 PLAYS A CRITICAL ROLE IN MODULATING THE HUMAN ENDOMETRIAL EPITHELIUM FOR RECEPTIVITY AND IMPLANTATION

Reproduction Fertility and Development ◽

10.1071/srb09abs529 ◽

2009 ◽

Vol 21 (9) ◽

pp. 128

Author(s):

G. Nie ◽

Y. Li ◽

L. A. Salamonsen ◽

C. Simon ◽

A. Quiñonero ◽

...

Keyword(s):

Epithelial Cells ◽

Molecular Mechanisms ◽

Cell Model ◽

Embryo Implantation ◽

Critical Role ◽

Proprotein Convertase ◽

Gynecological Disorders ◽

Proteomics Technology ◽

A Cell ◽

Endometrial Epithelium

Successful embryo implantation is an important step in establishing pregnancy, requiring a healthy embryo and a receptive endometrium. Establishment of endometrial receptivity involves morphological and physiological changes initially in the endometrial epithelium, but the underlying molecular mechanisms are not fully understood. We have previously demonstrated that proprotein convertase 5/6 (PC6), a member of the proprotein convertase (PC) family, is up-regulated in the endometrium specifically at implantation in association with epithelial differentiation, in the human and monkey. PCs convert a range of precursor proteins of important functions into their bioactive forms; they are thus regarded as critical “master switch” molecules. The present study aimed to determine whether PC6 is a critical regulator in the endometrial epithelium for receptivity and implantation. We examined whether endometrial epithelial PC6 dys-regulation is associated with implantation failure in women and whether knockdown of PC6 by siRNA in human endometrial epithelial cells affects embryo adhesion in a cell culture model. Endometrial PC6 expression was assessed by immunohistochemistry in the mid-secretory phase of the menstrual cycle (receptive phase) in two unique clinical cohorts comprising women of known fertility and infertility (with no obvious gynecological disorders, and with fertile males). Endometrial epithelial PC6 levels were significantly lower in infertile vs fertile women in both cohorts. To further establish that PC6 is important for receptivity, a cell model relevant to human implantation was used involving co-culture of uterine epithelial cells with mouse embryos. The epithelial cells were stably transfected with PC6 siRNA and PC6 knock down was confirmed at the levels of mRNA, protein, and activity by real-time RT-PCR, Western blotting and activity assay respectively. Embryos readily adhered to normal epithelial cells, but the adhesion was significantly reduced in the PC6 knockdown epithelial cells. We are currently using proteomics technology to identify the pathways affected by PC6 knockdown. These results strongly suggest that PC6 plays a critical role in modulating the human endometrial epithelium for receptivity and implantation.

Download Full-text

A Simple Model to Study Tau Pathology

Journal of Experimental Neuroscience ◽

10.4137/jen.s25100 ◽

2016 ◽

Vol 10 ◽

pp. JEN.S25100 ◽

Cited By ~ 10

Author(s):

Alexander L. Houck ◽

Félix Hernández ◽

Jesús Ávila

Keyword(s):

Cell Model ◽

Tau Proteins ◽

Human Embryonic Kidney ◽

Tau Pathology ◽

Pathological Conditions ◽

293 Cells ◽

Stable Manner ◽

A Cell ◽

Tau Kinases ◽

Gsk3 Inhibitor

Tau proteins play a role in the stabilization of microtubules, but in pathological conditions, tauopathies, tau is modified by phosphorylation and can aggregate into aberrant aggregates. These aggregates could be toxic to cells, and different cell models have been used to test for compounds that might prevent these tau modifications. Here, we have used a cell model involving the overexpression of human tau in human embryonic kidney 293 cells. In human embryonic kidney 293 cells expressing tau in a stable manner, we have been able to replicate the phosphorylation of intracellular tau. This intracellular tau increases its own level of phosphorylation and aggregates, likely due to the regulatory effect of some growth factors on specific tau kinases such as GSK3. In these conditions, a change in secreted tau was observed. Reversal of phosphorylation and aggregation of tau was found by the use of lithium, a GSK3 inhibitor. Thus, we propose this as a simple cell model to study tau pathology in nonneuronal cells due to their viability and ease to work with.

Download Full-text

Comparison of dietary polyphenols for protection against molecular mechanisms underlying nonalcoholic fatty liver disease in a cell model of steatosis

Molecular Nutrition & Food Research ◽

10.1002/mnfr.201600781 ◽

2017 ◽

Vol 61 (9) ◽

pp. 1600781 ◽

Cited By ~ 9

Author(s):

Hossein Rafiei ◽

Kosar Omidian ◽

Brian Bandy

Keyword(s):

Liver Disease ◽

Fatty Liver ◽

Nonalcoholic Fatty Liver Disease ◽

Fatty Liver Disease ◽

Molecular Mechanisms ◽

Cell Model ◽

Nonalcoholic Fatty Liver ◽

Dietary Polyphenols ◽

A Cell

Download Full-text

Synergy and antagonism of macroautophagy and chaperone-mediated autophagy in a cell model of pathological tau aggregation

Autophagy ◽

10.4161/auto.6.1.10815 ◽

2010 ◽

Vol 6 (1) ◽

pp. 182-183 ◽

Cited By ~ 59

Author(s):

Yipeng Wang ◽

Marta Martinez-Vicente ◽

Ulrike Krüger ◽

Susmita Kaushik ◽

Esther Wong ◽

...

Keyword(s):

Cell Model ◽

A Cell ◽

Tau Aggregation ◽

Chaperone Mediated Autophagy

Download Full-text

Molecular Mechanisms of EML in AML1/ETO+ AML and Its Targeting Treatments

Blood ◽

10.1182/blood.v124.21.5953.5953 ◽

2014 ◽

Vol 124 (21) ◽

pp. 5953-5953

Author(s):

Fan Yi Meng ◽

Ling Jiang ◽

Qingxiu Zhong ◽

Li Chun Wang ◽

Guopan Yu ◽

...

Keyword(s):

Cell Migration ◽

Protein Expression ◽

Molecular Mechanisms ◽

Conflicts Of Interest ◽

Cell Model ◽

In Vitro Study ◽

Control Group ◽

A Cell ◽

App Gene

Abstract Our previous study has been reported that AML1/ETO positive patients with highly expressed of APP were much easier to extramedullary infiltration, and got poor prognosis£¨followed-up median 35 ( 6-96 ) months, RFS in the high expression APP group was significantly lower than the low expression group £¬40.0% vs 80.0%£¬P = 0.001). In vitro study, we constructed a cell model kasumi-1 which was consistent with AML1/ETO positive and high expressed of APP gene. The cell migration was significantly reduced after interferce of APP expression. This study was designed to investigate the molecule mechanism of extramedullary leukemia (EML) in kasumi-1 cell model and to invent a strategy for treatment in clinic. In this study, we found p-ERK, c-Myc and MMP-2 were significantly decreased after APP expression knockdown in kasumi-1 cell. Meanwhile, we added the inhibitors to block p-ERK and c-Myc expression. The results showed that protein expression of p-ERK and c-Myc was significantly decreased after p-ERK inhibitor performance, which was proportional to the time and concentration. c-Myc and MMP-2 protein expression was significantly reduced after c-Myc inhibitor was used, but p-ERK didn't change (Fig.1B). So, we concluded that APP might regulated the AML cell migration via APP/p-ERK/c-Myc/MMP-2 pathway. Also, we found that kasumi-1 cell was resistant to adriamycin (ADM) and Ara-C, which meant APP may be related with drug resistance. So, we detected cell surviving fraction after ADM and Ara-C performance via MTT assay. The results showed that there was no difference in control group and siAPP group. But, when compared with controls groups, cell surviving fraction in siEZH2 group was significantly decreased after ADM and Ara-C performance respectively. Furthermore, we found protein expression of EZH2 was significantly reduced after LBH589 treatment in cell culture. So, we concluded that LBH589 or SiEZH2 could increase sensitivity of kasumi-1 cell to ADM and Ara-C. In sum, in AML1/ETO positive leukemia cells, we first report that APP gene regulates cell migration via APP/p-ERK/c-Myc/MMP-2 pathway and EZH2 gene induces drug resistantence. Interference or blocking of EZH2 and APP expression may be helpful in treating AML1/ETO positive leukemia. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Proteolytic processing of tau

Biochemical Society Transactions ◽

10.1042/bst0380955 ◽

2010 ◽

Vol 38 (4) ◽

pp. 955-961 ◽

Cited By ~ 79

Author(s):

Yipeng Wang ◽

Sarika Garg ◽

Eva-Maria Mandelkow ◽

Eckhard Mandelkow

Keyword(s):

Neurodegenerative Diseases ◽

Therapeutic Approach ◽

Cell Model ◽

Proteolytic Processing ◽

The Other ◽

Promising Therapeutic Approach ◽

A Cell ◽

Ad Alzheimer’S Disease ◽

Tau Aggregation ◽

Tau Cleavage

Tau aggregation is a hallmark of several neurodegenerative diseases, including AD (Alzheimer's disease), although the mechanism underlying tau aggregation remains unclear. Recent studies show that the proteolysis of tau plays an important role in both tau aggregation and neurodegeneration. On one hand, truncation of tau may generate amyloidogenic tau fragments that initiate the aggregation of tau, which in turn can cause toxicity. On the other hand, truncation of tau may result in tau fragments which induce neurodegeneration through unknown mechanisms, independently of tau aggregation. Blocking the truncation of tau thus may represent a promising therapeutic approach for AD or other tauopathies. In the present paper, we summarize our data on tau cleavage in a cell model of tauopathy and major results on tau cleavage reported in the literature.

Download Full-text

Oral (−)-Epicatechin Inhibits Progressive Tau Pathology in rTg4510 Mice Independent of Direct Actions at GSK3β

Frontiers in Neuroscience ◽

10.3389/fnins.2021.697319 ◽

2021 ◽

Vol 15 ◽

Author(s):

Katriona L. Hole ◽

Lydia E. Staniaszek ◽

Gayathri Menon Balan ◽

Jody M. Mason ◽

Jon T. Brown ◽

...

Keyword(s):

Glycogen Synthase ◽

Amyloid Β ◽

Paired Helical Filaments ◽

Tau Pathology ◽

Direct Inhibition ◽

Plaque Pathology ◽

A Cell ◽

Tau Aggregation ◽

Molecular Weight Form

Aggregation of the microtubule-associated protein tau into paired helical filaments (PHFs) and neurofibrillary tangles is a defining characteristic of Alzheimer’s Disease. Various plant polyphenols disrupt tau aggregation in vitro but display poor bioavailability and low potency, challenging their therapeutic translation. We previously reported that oral administration of the flavonoid (−)-epicatechin (EC) reduced Amyloid-β (Aβ) plaque pathology in APP/PS1 transgenic mice. Here, we investigated whether EC impacts on tau pathology, independent of actions on Aβ, using rTg4510 mice expressing P301L mutant tau. 4 and 6.5 months old rTg4510 mice received EC (∼18 mg/day) or vehicle (ethanol) via drinking water for 21 days and the levels of total and phosphorylated tau were assessed. At 4 months, tau appeared as two bands of ∼55 kDa, phosphorylated at Ser262 and Ser396 and was unaffected by exposure to EC. At 6.5 months an additional higher molecular weight form of tau was detected at ∼64 kDa which was phosphorylated at Ser262, Ser396 and additionally at the AT8 sites, indicative of the presence of PHFs. EC consumption reduced the levels of the ∼64 kDa tau species and inhibited phosphorylation at Ser262 and AT8 phosphoepitopes. Regulation of the key tau kinase glycogen synthase kinase 3β (GSK3β) by phosphorylation at Ser9 was not altered by exposure to EC in mice or primary neurons. Furthermore, EC did not significantly inhibit GSK3β activity at physiologically-relevant concentrations in a cell free assay. Therefore, a 21-day intervention with EC inhibits or reverses the development of tau pathology in rTg4510 mice independently of direct inhibition of GSK3β.

Download Full-text