Biology subjects

Chidambaram, H.

Publications and source records attributed to Chidambaram, H..

3 recordsLinked to original sources

bioRxiv2024

Extracellular HDAC6 ZnF UBP domain enhances podosome-mediated neuronal migration

The increasing prevalence of Alzheimers disease demands research into therapeutic strategies that go beyond Amyloid and Tau. Synaptic loss, neuritic loss, and microtubule destabilization due to misfolded Tau and dysfunctional signalling in the AD-affected neuron, all point toward understanding and targeting cytoskeletal dysregulation in AD. Here we present, an extensive study on the novel role of the ZnF UBP (Zinc Finger Ubiquitin Binding Protein) domain of HDAC6 (Histone Deacetylase 6) in actin remodelling in neurons. We have demonstrated this function through immunofluorescence colocalization analysis in actin-rich podosome structures. We have found that this HDAC6 domain induces increased localization of the actin polymerization proteins, Arp2 and WASP and the adaptor protein TKS5 in the podosome structures. We have also extended our work to understand the potential of this domain in enhancing the podosome-mediated migration of neuronal cells. It was thus established that HDAC6 ZnF UBP induces increased association of cytoskeletal proteins within the podosomes, conferring enhanced migration potential to neurons and presenting an interesting strategy to improve neuronal health.

cell biology↗

bioRxiv2024

Microglia undergoes chemokine receptor, CX3CR1-mediated internalization of extracellular Tau

In Alzheimers disease, the microtubule-associated protein, Tau misfolds to form aggregates and filaments in the intra- and extracellular region of neuronal cells. CX3CR1 receptor is involved in monomeric Tau internalization by directly binding to the receptor. In our study, we are interested in understanding the interaction of different pathological structures of Tau with microglial chemokine receptor, CX3CR1 and its role in CX3CR1-mediated Tau internalization by immunofluorescence assay. Co-immunoprecipitation further confirmed the receptor interaction with Tau oligomers and even aggregated filaments. We next determined the role of Tau as a chemoattractant in regulating the migration of microglia by wound healing assay. Further, immunolocalization studies of CX3CR1 with {beta}-arrestin proved the desensitization of CX3CR1 receptor upon Tau binding. Upon ligand interaction, GPCRs undergoes desensitization and encytosed to the cytosol. We have quantified the CX3CR1 internalization by measuring the membrane to cytosol intensity ratio of CX3CR1 receptor upon extracellular Tau exposure. In addition to experimental assays, a comprehensive analysis of the interaction between the CX3CR1 receptor, the Tau protein, and the AZD8797 ligand has been derived from the combined molecular docking, molecular dynamics and free energy calculations using molecular mechanics-generalized Born approach. In particular, two different molecular dynamics simulations were carried out for CX3CR1-Tau protein and AZD8797-bound CX3CR1-Tau protein interaction. The molecular modeling study establishes that AZD8797 binds to CX3CR1 receptor and modulates the Tau interaction with the receptor.

cell biology↗

bioRxiv2021

G-Protein coupled Purinergic P2Y12 receptor interacts and internalizes TauRD-mediated by membrane-associated actin cytoskeleton remodelling in microglia

In Alzheimers disease, the microtubule-associated protein, Tau misfolds to form aggregates and filaments in the intra- and extracellular region of neuronal cells. Microglial cells are the resident brain macrophage cells that are involved in constant surveillance and are activated by the extracellular deposits. Purinergic receptors are involved in chemotactic migration of microglial cells towards the site of inflammation. In our recent study, we found that microglial P2Y12 receptor has been involved in phagocytosis of full-length Tau species such as monomers, oligomers and aggregates by actin-driven chemotaxis. In this study, we have showed the interaction of repeat-domain of Tau (TauRD) with microglial P2Y12 receptor and analysed the corresponding residues for interaction by various in-silico approaches. In cellular studies, TauRD was found to interact with microglial P2Y12R and induces its cellular expression as confirmed by coimmunoprecipitation and western blot analysis respectively. Similarly, immunofluorescence microscopic studies emphasized that TauRD were phagocytosed by microglial P2Y12R via the membrane-associated actin remodelling as filopodia extension. Furthermore, the P2Yl2R-mediated TauRD internalization has activated the microglia with an increase in the Iba1 level and TauRD become accumulated at peri-nuclear region as localized with Iba1. Altogether, microglial P2Y12R interacts with TauRD and mediates directed migration and activation for its internalization.

neuroscience↗