Isolation and Detection of Pathological Tau Species in a Tauopathy Mouse Model.

Tau protein in Alzheimer's disease (AD) and tauopathies becomes insoluble due to hyperphosphorylation, conformational alterations, and aggregation. To analyze insoluble tau and pathological tau species, this study employs a methodology that utilizes wild-type and transgenic tau mice (P310S Tau) tissue extraction using 1% Sarkosyl or N-Lauroylsarcosine sodium salt and the radio immunoprecipitation assay (RIPA) buffer. However, the commonly used methods to study the insoluble tau fraction using detergents like Sarkosyl and RIPA require a large amount of homogenate, which can pose challenges when dealing with small tissue samples. Additionally, the study employs immunohistochemistry to visualize and quantify the pathological tau species in the brain tissue of transgenic mice, aiming to identify and analyze pathological tau species such as hyperphosphorylated tau to further our understanding of tauopathies such as Alzheimer's disease.

Interaction of Tau with Kinesin-1: Effect of Kinesin-1 Heavy Chain Elimination on Autophagy-Mediated Mutant Tau Degradation.

Natively unfolded tau has a low propensity to form aggregates, but in tauopathies, such as Alzheimer's disease (AD), tau aggregates into paired helical filaments (PHFs) and neurofibrillary tangles (NFTs). Multiple intracellular transport pathways utilize kinesin-1, a plus-end-directed microtubule-based motor. Kinesin-1 is crucial in various neurodegenerative diseases as it transports multiple cargoes along the microtubules (MT). Kinesin-1 proteins cannot progress along MTs due to an accumulation of tau on their surfaces. Although kinesin-1-mediated neuronal transport dysfunction is well-documented in other neurodegenerative diseases, its role in AD has received less attention. Very recently, we have shown that knocking down and knocking out of kinesin-1 heavy chain (KIF5B KO) expression significantly reduced the level and stability of tau in cells and tau transgenic mice, respectively. Here, we report that tau interacts with the motor domain of KIF5B in vivo and in vitro, possibly through its microtubule-binding repeat domain. This interaction leads to the inhibition of the ATPase activity of the motor domain. In addition, the KIF5B KO results in autophagy initiation, which subsequently assists in tau degradation. The mechanisms behind KIF5B KO-mediated tau degradation seem to involve its interaction with tau, promoting the trafficking of tau through retrograde transport into autophagosomes for subsequent lysosomal degradation of tau. Our results suggest how KIF5B removal facilitates the movement of autophagosomes toward lysosomes for efficient tau degradation. This mechanism can be enabled through the downregulation of kinesin-1 or the disruption of the association between kinesin-1 and tau, particularly in cases when neurons perceive disturbances in intercellular axonal transport.

Reduction of kinesin I heavy chain decreases tau hyperphosphorylation, aggregation, and memory impairment in Alzheimer's disease and tauopathy models.

Many neurodegenerative diseases, such as Alzheimer's disease (AD) and frontotemporal dementia with Parkinsonism linked to chromosome 17, are characterized by tau pathology. Numerous motor proteins, many of which are involved in synaptic transmission, mediate transport in neurons. Dysfunction in motor protein-mediated neuronal transport mechanisms occurs in several neurodegenerative disorders but remains understudied in AD. Kinesins are the most important molecular motor proteins required for microtubule-dependent transport in neurons, and kinesin-1 is crucial for neuronal transport among all kinesins. Although kinesin-1 is required for normal neuronal functions, the dysfunction of these motor domains leading to neurodegenerative diseases is not fully understood. Here, we reported that the kinesin-I heavy chain (KIF5B), a key molecular motor protein, is involved in tau homeostasis in AD cells and animal models. We found that the levels of KIF5B in P301S tau mice are high. We also found that the knockdown and knockout (KO) of KIFf5B significantly decreased the tau stability, and overexpression of KIF5B in KIF5B-KO cells significantly increased the expression of phosphorylated and total tau levels. This suggested that KIF5B might prevent tau accumulation. By conducting experiments on P301S tau mice, we showed that partially reducing KIF5B levels can reduce hyperphosphorylation of the human tau protein, formation of insoluble aggregates, and memory impairment. Collectively, our results suggested that decreasing KIF5B levels is sufficient to prevent and/or slow down abnormal tau behavior of AD and other tauopathies.

OCT4-mediated transcription confers oncogenic advantage for a subset of gastric tumors with poor clinical outcome.

Deregulated transcription programs and signaling pathways are the critical factors involved in the process of carcinogenesis. Signaling pathway-based classification of tumors is expected to pave the way for the development of targeted therapeutics. We investigated the OCT4-mediated transcription program in the gene expression profiles of 939 gastric tumor samples. A set of 84 genes showing positive correlation with the activation pattern of the available OCT4 gene sets were found to consistently express in diffuse, poorly differentiated, and stage-III gastric tumors with poor prognosis. We also developed stable OCT4-silenced gastric cancer cells and the resultant gene expression changes were investigated by genome-wide mRNA profiling. Functional genomic investigation of the genes downregulated in OCT4-silenced cells and the pathways co-activated with OCT4 gene set across gastric tumors revealed the positive association of dysregulated OCT4 with TGF-ß, GLI, PRC2/EzH2, Wnt, KRAS, STK33, and YAP signaling pathways in diffuse subtype gastric tumors. Elevated expression of OCT4 gene set was identified to represent the previously described EMT_UP as well as the GENOMICALLY STABLE subtypes of gastric tumors. Integrative genomic screening of the drug sensitivity of gastric cancer cells in correlation with the expression of OCT4 gene set across drug sensitivity databases revealed the inhibitors of tyrosine kinases, HDAC, and HSP90 to have a negative correlation and needs to be investigated for their potential therapeutic features for the subset of OCT4-activated gastric tumors. Thus, the subset of gastric tumors with OCT4 activation, the associated oncogenic signaling pathways, and potential therapeutic candidates were identified for the development of targeted therapeutic strategies.

Alzheimer's Disease and other Tauopathies: Exploring Efficacy of Medicinal Plant-derived Compounds in Alleviating Tau-mediated Neurodegeneration.

Alzheimer's disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-ß (Aß) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick's disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recent unsuccessful phase III clinical trials related to Aß- targeted therapeutic drugs have indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies focused on medicinal plant- derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We have mainly considered the studies focused on Tau protein as a therapeutic target. We have reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

Identification of the targeted therapeutic potential of doxycycline for a subset of gastric cancer patients.

The identification of new drugs for the targeted therapy of gastric cancer remains an important need. The RAS/RAF/MEK/ERK/ELK1 signaling cascade is activated in many cancers, including gastric cancer. To identify the targetable inhibitors of the ERK/MAPK pathway, we performed a repurposing screening of a panel of antimicrobial agents in gastric cancer cells using an ERK/MAPK-driven firefly luciferase reporter assay. Multiple antibiotics were identified to inhibit ERK-mediated transcriptional activity. Among them, doxycycline showed high inhibition of ERK/MAPK-regulated transcriptional activity and the levels of ERK proteins. Doxycycline was further identified to inhibit the proliferation and the colony- and spheroid-forming potential of gastric cancer cells. By in vitro signaling pathway and genome-wide expression profiling analyses, doxycycline was identified to inhibit signaling pathways and transcriptional activities regulated by ER, Myc, E2F1, Wnt, SMAD2/3/4, Notch, and OCT4. Doxycycline was also found to activate p53-, ATF6-, NRF1/2-, and MTF1-mediated transcription and inhibit the transcription of histones, proteasomal genes, fibroblast growth factor, and other oncogenic factors. These observations show the multitargeting and targeted therapeutic features of doxycycline for a subset of gastric tumors.

Integrative transcriptome analysis of liver cancer profiles identifies upstream regulators and clinical significance of ACSM3 gene expression.

PURPOSE: Hepatocellular carcinoma (HCC) is one of the most common human malignancies. It has frequently been associated with metabolic perturbations and liver damages. Various members of the family of acyl-CoA synthetases are known to be involved in the production of bioactive fatty acids, and altered expression of its encoding genes has been found to be involved in metabolic perturbations. For the development of novel diagnostic and therapeutic HCC options, a fundamental understanding of the mechanisms associated with the deregulation of candidate genes involved in metabolic perturbation is required. METHODS: A meta-analysis of multiple HCC mRNA profiles was performed to identify consistently deregulated genes. Expression of the acyl-CoA synthetase medium chain family member 3 (ACSM3) gene was subsequently assessed in different HCC tumor stages and correlated with various clinicopathological features. Transcription regulation, survival and pathway-associated features of the ACSM3 gene were investigated using integrative functional genomic and molecular cell biological methods. RESULTS: We found that expression of the ACSM3 gene was significantly reduced in HCC tissues and was frequently downregulated in patients exhibiting high alpha-fetoprotein (AFP) levels, high alanine aminotransferase (ALT) levels, multiple nodules and large tumors. Loss of ACSM3 expression was found to correlate with advanced HCC stages and a poor survival. In addition, HNF4α was found to positively regulate the expression of the ACSM3 gene, while PPARγ was found to transcriptionally repress it. Downregulation of ACSM3 expression was perceived upon activation of the TGFß, WNT, AKT and MYC signalling pathways. In addition, we found that ACSM3 expression correlates with fatty acid oxidation in HCC. CONCLUSION: Our data provide evidence for a differential expression and regulation of the ACSM3 gene in HCC, and may lay a foundation for therapeutically targeting fatty acid metabolism in these tumors.

NFκB activation demarcates a subset of hepatocellular carcinoma patients for targeted therapy.

BACKGROUND: Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. It is a heterogeneous disorder and >80 % of the tumors develop in patients with liver cirrhosis, resulting from chronic inflammation and/or fibrosis. Here, we set out to identify novel targets for HCC therapy and to define a subgroup of patients that might benefit most from it. METHODS: Cellular pathway activation profiling of 45 transcription factors in a HCC-derived cell line (HEP3B), in vitro analysis of NFκB reporter activity in additional HCC-derived cell lines and pathway-focused integrative analyses of publicly available primary HCC-derived expression profiling data (GSE6764, GSE9843, E-TABM-36 and E-TABM-292) were employed to reveal a role of NFκB in HCC development. In order to identify potential targeting agents, a luciferase-based NFκB reporter screening assay was established in HEP3B cells. After screening of a drug library through this assay, a potent NFκB pathway inhibitor was identified and characterized using an array of additional in vitro assays. RESULTS: Using cellular pathway activation profiling, we found a high activation of NFκB-mediated signaling in HCC-derived cell lines and in primary HCC tumors. Through NFκB inhibitor screening we observed a highly efficacious NFκB pathway inhibitory potential of ornithogalum in HCC-derived HEP3B cells. Although its active component still remains to be defined, ornithogalum has been found to inhibit endoplasmic reticulum (ER) and oxidative stress responses. ER stress, oxidative stress and NFκB signaling were found to be enhanced in a subset of HCCs, as well as in (precancerous) liver cirrhosis tissues. CONCLUSION: From our data we conclude that NFκB signaling is activated in precancerous cirrhosis tissues and in a subset of HCCs. We found that ornithogalum exhibits NFκB targeting and stress relieving activities. NFκB inhibitors, including the active component of ornithogalum, may serve as putative preventive and targeted therapeutic agents for at least a subset of HCCs in which the NFκB pathway is activated. These latter notions require further investigation in a translational context.