Endoplasmic Reticulum function-structure in neuronal (patho)physiology
Cells of high organisms compartmentalise a variety of biochemical milieus in several membrane-enclosed organelles (nucleus, mitochondria, endoplasmic reticulum etc.) each shaped and equipped to perform its specialised function(s), endowing the organism with almost unlimited functional versatility. The Endoplasmic Reticulum (ER) is an assembly of perinuclear membranous sheets interconnected with a contiguous network of tubes extending throughout the entire cell periphery. The functions of this organelle encompass manufacturing of secretory/membrane proteins and lipids, calcium storage, detox and distribution of bioactive substances to the cell periphery.
Understanding of how the multitude of ER functionalities is supported by its intricate and highly dynamic structure is crucial for rationalising the abundantly evident sensitivity of the neuronal system in particular to the perturbations in ER functionality (prominently exemplified by causative association of ER morphogens, aka ER shaping proteins, with neuropathologies such as Hereditary Spastic Paraplegia and their involvement in dementia).
We seek understanding of how the ER’s function-structure relationships play out in neuronal cells’ normal functioning and disease. In our quests we rely on the combination of techniques such as high tempora-spatial resolution light microscopy, genetically encoded biosensing, gene-manipulation tools and in vitro/in vivo biochemistry.
ER dynamics and morpho-regulation
In this project we study processes governing the ER network’s morphological regulation, and how these define neuronal ER functionalities. We focus on studying properties of the ER defining the efficiency of its luminal and membrane material transport/distribution to the distant periphery, a process particularly relevant for neuronal geometry, and surveying aspects of neuronal cell health/functioning dependent on the ER conveyance efficiency.
ER compartmentalises oxidative activities of the Cell (e.g. disulphide bonding in oxidative secretory protein folding). While ER luminal components thrive in an oxidising and ROS-rich environment, such conditions are not tolerable in the neighbouring cytoplasm and the nucleus. However, ROS are utilised by cells as secondary messengers. Fine time-space regulation of ROS is vital to avoid their toxicity. Elevated ROS (oxidative stress) accompany dementia pathologies. We study the ER RedOx regulation and insulation, focusing on characterising the mechanisms and players behind handling of ROS (hydrogen peroxide in particular) as well as reductive equivalents by this organelle, with a view to understand ER’s contribution to the RedOx/ROS dysregulation associated with neurodegenerative conditions and explore potential intervention opportunities within the ER RedOx systems.To facilitate these studies, we use and develop genetically encoded probes for monitoring RedOx/ROS in live cells.
Cellular mechanism for handling of protein aggregates
Cells maintain dynamic protein homeostasis, ensuring a manageable load of unfolded proteins and adequate availability of the protein folding machinery. In healthy proteostasis nascent proteins are chaperoned through the functional folding route avoiding misfolding and aggregation. Dementia-related pathologies are associated with a disbalanced proteostasis manifested in aggregation of several particularly aggregation-prone proteins (e.g. TAU, a-betta, a-synuclein etc.). In this project we develop live cell imaging-compatible protein aggregation-sensing techniques to study cellular mechanisms and factors behind aggregation-predisposing cellular conditions, and those involved in protein aggregates’ turn-over, with a view to identify intervention targets for controlling aggregates’ accumulation.