@article {44532, title = {Multi-faceted role of melatonin in neuroprotection and amelioration of tau aggregates in alzheimer{\textquoteright}s disease}, journal = {Journal of Alzheimers Disease}, volume = {62}, year = {2018}, month = {MAY}, pages = {1481-1493}, abstract = {

Alzheimer{\textquoteright}s disease (AD) is one of the major age related neurodegenerative diseases whose pathology arises due to the presence of two distinct protein aggregates, viz., amyloid-beta plaques in extracellular matrix and tau neurofibrillary tangles in neurons. Multiple factors play a role in AD pathology, which includes familial mutations, oxidative stress, and post-translational modifications. Melatonin is an endocrine hormone, secreted during darkness, derived from tryptophan, and produced mainly by the pineal gland. It is an amphipathic molecule, which makes it suitable to cross not only blood-brain barrier, but also to enter several other subcellular compartments like mitochondria and endoplasmic reticulum. In this context, the neuroprotective effect of melatonin may be attributed to its role as an antioxidant. Melatonin{\textquoteright}s pleiotropic function as an antioxidant and neuroprotective agent has been widely studied. However, its direct effect on the aggregation of tau and amyloid-beta needs to be explored. Furthermore, an important aspect of its function is its ability to regulate the process of phosphorylation of tau by affecting the function of kinases and phosphatases. In this review, we are focusing on the pleiotropic function of melatonin on the aspect of its neuroprotective function in tau pathology, which includes antioxidant function, regulation of enzymes, including kinases and enzymes involved in free radical scavenging and mitochondrial protection.

}, keywords = {Alzheimer{\textquoteright}s disease, hyperphosphorylation, melatonin, mitochondria, Protein aggregation, tau protein}, issn = {1387-2877}, doi = {10.3233/JAD-170900}, author = {Balmik, Abhishek Ankur and Chinnathambi, Subashchandrabose} } @article {47164, title = {Baicalein suppresses repeat tau fibrillization by sequestering oligomers}, journal = {Archives of Biochemistry and Biophysics}, volume = {675}, year = {2019}, month = {OCT}, pages = {108119}, type = {Article}, abstract = {

Alzheimer{\textquoteright}s disease (AD) is a neurodegenerative disorder caused by protein misfolding, aggregation and accumulation in the brain. A large number of molecules are being screened against these pathogenic proteins but the focus for therapeutics is shifting towards the natural compounds as aggregation inhibitors, mainly due to their minimum adverse effects. Baicalein is a natural compound belonging to the class of flavonoids isolated from the Chinese herb Scutellaria baicalensis. Here we applied fluorescence, absorbance, microscopy, MALDI-TOF spectrophotometry and other biochemical techniques to investigate the interaction between Tau and Baicalein in vitro. We found the aggregation inhibitory properties of Baicalein for the repeat Tau. Overall, the potential of Baicalein in dissolving the preformed Tau oligomers as well as mature fibrils can be of utmost importance in therapeutics for Alzheimer{\textquoteright}s disease.

}, keywords = {Alzheimer disease, Baicalein, Microtubule assembly, Paired helical filaments, Protein aggregation, tau protein}, issn = {0003-9861}, doi = {10.1016/j.abb.2019.108119}, author = {Sonawane, Shweta Kishor and Balmik, Abhishek Ankur and Boral, Debjyoti and Ramasamy, Sureshkumar and Chinnathambi, Subashchandrabose} } @article {46842, title = {Effect of melatonin on tau aggregation and tau-mediated cell surface morphology}, journal = {International Journal of Biological Macromolecules}, volume = {152}, year = {2020}, month = {JUN }, pages = {30-39}, type = {Article}, abstract = {

Aggregation of Microtubule-associated protein Tau and its deposition in the form of neurofibrillary tangles (NFTs) is one of the pathological hallmarks of Alzheimer{\textquoteright}s disease (AD). Tau aggregation inhibition has been targeted in various studies including natural compounds and synthetic small molecules. Here, we have studied neurohormone- Melatonin against in vitro Tau aggregation and observed its effect on membrane topology, tubulin network and Tau phosphorylation in Neuro2A and N9 cell lines. The aggregation and conformation of Tau was determined by ThT fluorescence and CD spectroscopy respectively. The morphology of Tau aggregates in presence and absence of Melatonin was studied by transmission electron microscopy. Melatonin was found to reduce the formation of higher order oligomeric structures without affecting the overall aggregation kinetics of Tau. Melatonin also modulates and helps to maintain membrane morphology, independent on tubulin network as evidenced by FE-SEM and immunofluorescence analysis. Overall, Melatonin administration shows mild anti-aggregation and cytoprotective effects. (C) 2020 Elsevier B.V. All rights reserved.

}, keywords = {Alzheimer{\textquoteright}s disease, Cell surface morphology, melatonin, Paired helical filaments, tau protein, Tauopathies}, issn = {0141-8130}, doi = {10.1016/j.ijbiomac.2020.01.296}, author = {Das, Rashmi and Balmik, Abhishek Ankur and Chinnathambi, Subashchandrabose} } @article {46945, title = {Melatonin interacts with repeat domain of Tau to mediate disaggregation of paired helical filaments}, journal = {Biochimica Et Biophysica Acta-General Subjects}, volume = {1864}, year = {2020}, month = {MAR}, pages = {129467}, type = {Article}, abstract = {

Tau is the major neuronal protein involved in the stabilization of microtubule assembly. In Alzheimer{\textquoteright}s disease, Tau self-assembles to form intracellular protein aggregates which are toxic to cells. Various methods have been tried and tested to restrain the aggregation of Tau. Most of the agents tested for this purpose have limitations in their effectiveness and availability to neuronal cells. We have tested melatonin, a neurohormone secreted by pineal gland and a well-known anti-oxidant, for its ability to interact with the repeat domain of Tau using ITC and NMR. In aggregation inhibition and disaggregation studies of repeat Tau, melatonin was found to modulate the aggregation propensity of repeat Tau at a concentration of 5000 mu M and was more effective in dissolving preformed aggregates rather than acting as an aggregation inhibitor. However, there were no major conformational changes in Tau in presence of melatonin as observed by CD spectroscopy. On the basis of our findings, we are proposing a mechanism by which melatonin can interact with the repeat domain of Tau and exhibit its disaggregation effect.

}, keywords = {Alzheimer{\textquoteright}s disease, Disaggregation, melatonin, Paired helical filaments, tau protein, Tauopathies}, issn = {0304-4165}, doi = {10.1016/j.bbagen.2019.129467}, author = {Balmik, Abhishek Ankur and Das, Rashmi and Dangi, Abha and Gorantla, Nalini Vijay and Marelli, Udaya Kiran and Chinnathambi, Subashchandrabose} }