PhD student, Institute of Molecular and Translational Medicine, Palacky University, Olomouc
Focused on therapeutic strategy for Alzheimer's disease
Alzheimer's disease (AD) is one of the leading cause of death in developed countries characterized by plaques and tangles in the brain causes cognitive decline in elderly population. This is the only disease which has no early diagnosis and treatment. My focus is on the protein aggregates called tau tangles and its phosphorylating kinases. When this tau protein is hyperphosphorylated it will aggregate and causes microtubule disruption results in the loss of nutrient, signal transport between neurons causes neuronal loss. These tau aggregates then causes neurodegeneration and impairment cognitive function of the brain. Elderly people affected with dementia (loss of memory) will not be able to identify their family, relatives and even themselves at severe stages of the disease. Around 45 million people living with Alzheimer's disease worldwide makes Alzheimer's research community to find the new treatment strategies. So finding inhibitors against the kinases that are responsible for the tau aggregation is an important strategy. My another topic is focused on inhibiting the aggregation process with small molecule compounds which can cross blood-brain barrier for effective treatment. I am also focused on using compounds to clear the pre-formed tau aggregates.This strategy will be really effective for the treatment of Alzheimer's disease as the disease causes mental and financial burdens in people's lives.
Abstract: Excessive activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome is involved in many chronic inflammatory diseases, including cardiovascular and Alzheimer's disease. Here we show that microtubule-affinity regulating kinase 4 (MARK4) binds to NLRP3 and drives it to the microtubule-organizing centre, enabling the formation of one large inflammasome speck complex within a single cell. MARK4 knockdown or knockout, or disruption of MARK4-NLRP3 interaction, impairs NLRP3 spatial arrangement and limits inflammasome activation. Our results demonstrate how an evolutionarily conserved protein involved in the regulation of microtubule dynamics orchestrates NLRP3 inflammasome activation by controlling its transport to optimal activation sites, and identify a targetable function for MARK4 in the control of innate immunity.
Pub.: 29 Jun '17, Pinned: 18 Jul '17
Abstract: Alzheimer's disease is the most common neurodegenerative disease, and there are no mechanism-based therapies. The disease is defined by the presence of abundant neurofibrillary lesions and neuritic plaques in the cerebral cortex. Neurofibrillary lesions comprise paired helical and straight tau filaments, whereas tau filaments with different morphologies characterize other neurodegenerative diseases. No high-resolution structures of tau filaments are available. Here we present cryo-electron microscopy (cryo-EM) maps at 3.4-3.5 Å resolution and corresponding atomic models of paired helical and straight filaments from the brain of an individual with Alzheimer's disease. Filament cores are made of two identical protofilaments comprising residues 306-378 of tau protein, which adopt a combined cross-β/β-helix structure and define the seed for tau aggregation. Paired helical and straight filaments differ in their inter-protofilament packing, showing that they are ultrastructural polymorphs. These findings demonstrate that cryo-EM allows atomic characterization of amyloid filaments from patient-derived material, and pave the way for investigation of a range of neurodegenerative diseases.
Pub.: 06 Jul '17, Pinned: 18 Jul '17
Abstract: Aggregation of amyloid-β (Aβ) and tau plays a crucial role in the onset and progression of Alzheimer's disease (AD). Therefore, the inhibition of Aβ and tau aggregation may represent a potential therapeutic target for AD. Herein, we designed and synthesized both Aβ and tau dual aggregation inhibitors based on the structure of curcumin and developed the novel curcumin derivative PE859. In this study, we investigated the inhibitory activity of PE859 on Aβ aggregationin vitro and the therapeutic effects of PE859 on cognitive dysfunction via dual inhibition of Aβ and tau aggregation in vivo. PE859 inhibited Aβ aggregation in vitro and protected cultured cells from Aβ-induced cytotoxicity. Furthermore, PE859 ameliorated cognitive dysfunction and reduced the amount of aggregated Aβ and tau in brains of senescence-accelerated mouse prone 8 (SAMP8). These results warrant consideration of PE859 as a candidate drug for AD.
Pub.: 10 Jun '17, Pinned: 28 Jun '17
Abstract: Anti-aggregation drugs play an important role in therapeutic approaches for Alzheimer's disease. We have previously developed a number of compounds that are able to inhibit the pathological aggregation of Tau protein. One common obstacle to application is the limited penetration across the plasma membranes into cells, where Tau aggregation occurs in the cytosol. We used an inducible N2a cell line which expresses the repeat domain of tau and develops tau aggregates.Several peptide-polymer conjugates were synthesized to enhance the uptake of compounds into cells and thus to improve their biomedical application. The aim of this study was to test whether the peptide-inhibitor complexes still retain their inhibitory activity on Tau aggregation.We screened peptide sequences with high binding capacity to a subset of aggregation inhibitors and identified them by fluorescence microscopy and MALDI MS/MS with regard to drug solubilization. To explore whether the synthesized complexes can influence the aggregation propensity of Tau we performed in vitro and cellular assays. The effect on toxicity was investigated by measuring apoptosis markers.The tested peptide-compound complexes show no decrease in the total Tau levels but decreased ratios of soluble to pelletable Tau species. This indicates a conversion of insoluble Tau oligomers into soluble forms which appear to be less toxic than the insoluble ones, as seen by a decrease of apoptotic cells. Thus the peptide-compound complexes have a higher potency than the compounds alone due to improved bioavailability of the drug.
Pub.: 06 Feb '17, Pinned: 27 Jun '17
Abstract: The aggregation of Tau protein is a hallmark of neurodegenerative diseases including Alzheimer's disease. Previously, we generated a cell model of tauopathy based on the 4-repeat domain with the FTDP-17 mutation ΔK280 (Tau(4RDΔK)) which is expressed in a regulatable fashion (tet-on). The deletion variant ΔK280 is highly amyloidogenic and forms fibrous aggregates in neuroblastoma N2a cells staining with the reporter dye Thioflavin S. The aggregation of Tau(4RDΔK) is toxic, contrary to wildtype or anti-aggregant variants of the protein. Using a novel approach for monitoring in situ Tau aggregation and toxicity by combination of microscopic analysis with FACS and biochemical analysis of cells enabled the dissection of the aggregating species which cause a time-dependent increase of toxicity. The dominant initiating step is the dimerization of Tau(4RDΔK) which leads to further aggregation and induces a strong increase in reactive oxygen species (ROS) and cytoplasmic Ca(2+) which damage the membranes and cause cell death. Tau-based treatments using Tau aggregation inhibitors reduce both soluble oligomeric and fully aggregated Tau species and decrease their toxicity.
Pub.: 11 Jun '17, Pinned: 27 Jun '17