Photo-Excited Toluidine Blue Disaggregates the Repeat Tau and Modulates End-Binding Protein EB1, Cytoskeletal Structure in Neuronal Cells.

BACKGROUND/AIMS: Alzheimer's disease is a progressive neurological disorder characterized by the intracellular accumulation of Tau protein aggregates. In the present work, we studied the effect of Toluidine Blue and photo-excited Toluidine Blue on the aggregation of repeat Tau using in vitro assays. METHODS: The in vitro experiments were carried out on recombinant repeat Tau which was purified by cation exchange chromatography. The ThS fluorescence analysis was used to study the aggregation kinetics of Tau. CD spectroscopy and electron microscopy were used to study the secondary structure and morphology of Tau respectively. The actin cytoskeleton modulation was studied in Neuro2a cells with help of immunofluorescent microscopy. RESULTS: Results showed that Toluidine Blue efficiently inhibited the formation of higher-order aggregates, which was evidenced by Thioflavin S fluorescence assay, SDS-PAGE, and TEM. Immunofluorescence studies on the cytoskeleton of Neuro2a cells showed that Toluidine Blue and photo-excited Toluidine Blue treatment at a non-toxic concentration of 0.5 µM stimulated the formation of actin-rich lamellipodia and filopodia structures. Tubulin networks were also differentially modulated after the treatment of Toluidine Blue and photo-excited Toluidine Blue. End-binding protein 1 (EB1) levels were observed to increase after Toluidine Blue and photo-excited Toluidine Blue treatment indicating accelerated microtubule polymerization. CONCLUSION: The overall study suggested that Toluidine Blue inhibited the aggregation of soluble Tau and photo-excited Toluidine Blue disaggregated the pre-formed Tau filaments. In our study, TB and PE-TB were observed to be potent against Tau aggregation. We observed a distinctive modulation of actin, tubulin networks, and EB1 levels after TB and PE-TB treatment, which suggested that TB and PE-TB have potency against cytoskeleton deformities.

Bacopa monnieri reduces Tau aggregation and Tau-mediated toxicity in cells.

Alzheimer's disease is a neurodegenerative disease characterized by progressive memory loss and behavioral impairments. In the present study, the ethanolic extract of Bacopa monnieri was studied for its potency to inhibit Tau aggregation and rescuing of the viability of Tau-stressed cells. Bacopa monnieri was observed to inhibit the Tau aggregation in vitro. The cells exposed to Bacopa monnieri were also observed to have a low level of ROS and caspase-3 activity. The immunoblot and immunofluorescence analysis showed that Bacopa monnieri acts as an antioxidant and restored the Nrf2 levels in Neuro2a cells. Bacopa monnieri treatment to Neuro2a cells was observed to reduce the phospho-Tau load in formaldehyde-stressed cells. Furthermore, the treatment of Bacopa monnieri reduced the phosphorylation of GSK-3ß in formaldehyde-stressed cells. Ran and NUP358 are the key proteins involved in nuclear transport. It was observed that formaldehyde treatment impaired the nuclear transport by missorting the NUP358 arrangement in Neuro2a cells. On the contrary, Bacopa monnieri treatment restored the NUP358 arrangement in cells. The overall results of the present study suggested that Bacopa monnieri could be considered a potent herb against Tau phosphorylation and Tau aggregation, which projects it as a promising formulation for Alzheimer's disease.

The inhibitory effect of Curcumin-Artemisinin co-amorphous on Tau aggregation and Tau phosphorylation.

Tau is a natively unfolded microtubule-associated protein. Tau neurofibrillary tangles are one of the hallmarks of Alzheimer's disease. The post-translational modifications of Tau lead to its pathological state. Phosphorylation is the key post-translational modification associated with Tauopathy. Curcumin is a polyphenolic compound present in the rhizomes of Curcuma longa. Curcumin has been reported to have remarkable medicinal properties in several diseases, but its poor solubility limits its therapeutic potency. Artemisinin is a sesquiterpene lactone, which has been known sience ancient times for its applications as a treatment for various diseases such as malaria, cancer, autoimmune disease, etc. In the present study, the potency of crystalline curcumin, crystalline artemisinin, and Cur-Art co-amorphous dispersion were evaluated against Tau pathology. The in-vitro ThS/ANS fluorescence and electron microscopy results suggested that curcumin and Cur-Art efficiently inhibited Tau aggregation. Furthermore, exposure to curcumin and Cur-Art co-amorphous restored the impaired nuclear transport in formaldehyde-stressed cells. Curcumin was also found to modulate the phosphorylation of Tau, which indicated the neuroprotective potency. Thus, curcumin and Cur-Art co-amorphous exhibit therapeutic potential against Tau protein in Alzheimer's disease.

Epiphytic Microbial Diversity of Vitis vinifera Fructosphere: Present Status and Potential Applications.

Vineyard provides an apt environment for growth of different types of microorganisms. The microbial domain is greatly affected by changing climatic conditions, geographical region, water activity, agricultural practices, presence of different pathogens and various pests. Grapevine microbial diversity is also affected by different stages of plant growth. Epiphytic berry microflora is specifically influenced by developmental phases and plays an important role in winemaking which is studied extensively. However, very little information is available about microbial community associated with table grape berries, which are consumed as fresh fruits. Moreover, our knowledge about the important role played by these microbes is precise and their scope might be larger than what is existing in the public domain. A systematic study on effect of developmental stages of table grape berries on microbial diversity would provide new insights for exploring the applicability of these microbes in plant growth, crop protection and bioremediation. In this review, we propose an effort to relate the developmental stages of grape berry with microbial consortium present and at the same time discuss the possible applications of these microbes in plant protection and biodegradation.

Role of Microglia in Regulating Cholesterol and Tau Pathology in Alzheimer's Disease.

Cholesterol, a principal constituent of the cell membrane, plays a crucial role in the brain by regulating the synaptic transmission, neuronal signaling, as well as neurodegenerative diseases. Defects in the cholesterol trafficking are associated with enhanced generation of hyperphosphorylated Tau and Amyloid-ß protein. Tau, a major microtubule-associated protein in the brain, is the key regulator of the mature neuron. Abnormally hyperphosphorylated Tau hampers the major functions related to microtubule assembly by promoting neurofibrillary tangles of paired helical filaments, twisted ribbons, and straight filaments. The observed pathological changes due to impaired cholesterol and Tau protein accumulation cause Alzheimer's disease. Thus, in order to regulate the pathogenesis of Alzheimer's disease, regulation of cholesterol metabolism, as well as Tau phosphorylation, is essential. The current review provides an overview of (1) cholesterol synthesis in the brain, neurons, astrocytes, and microglia; (2) the mechanism involved in modulating cholesterol concentration between the astrocytes and brain; (3) major mechanisms involved in the hyperphosphorylation of Tau and amyloid-ß protein; and (4) microglial involvement in its regulation. Thus, the answering key questions will provide an in-depth information on microglia involvement in managing the pathogenesis of cholesterol-modulated hyperphosphorylated Tau protein.