Skeletal disorders such as osteoporosis, osteoarthritis and osteosarcoma are characterised by disruptions in bone homeostasis driven by molecular and cellular dysregulation. Master regulators of homeostatic bone health that can influence the dynamic balance between bone formation and bone resorption are promising therapeutic targets for these skeletal diseases. Paraspeckles are nuclear regulatory hubs increasingly implicated in the molecular regulation of bone homeostasis. Paraspeckles are large membrane-less structures built upon a NEAT1 long non-coding RNA backbone when bound to paraspeckle proteins such as NONO, SFPQ and FUS.1 Once formed, paraspeckles play a key role in regulating the surrounding nuclear landscape via sequestration of RNA and RNA-binding proteins.1 In the context of skeletal metabolism, paraspeckles can influence osteoclastogenesis as well as promote osteogenesis via RUNX2-related pathways in osteoblasts.^{2, 3} This regulation in the context of skeletal health is being increasingly explored; albeit the relevance of paraspeckles in osteocyte health specifically is unknown, despite osteocytes being known as the primary mechanosensory and most cell abundant in bone.4

My project aims to understand the role of paraspeckles in osteocyte health using MLO-Y4 cells, particularly under mechanical stress. Previously as part of my PhD thesis, I have used hypo-osmotic stress as a proxy for mechanical stress. We have observed nuclear and cell rearrangement in osteocytes with an observed reduction in paraspeckle assembly. We are currently investigating whether this paraspeckle disassembly is mechanically induced or osmotically relevant as well as assessing the consequences of this on osteocyte health. In a new study to further understand mechanotransduced paraspeckle assembly in osteocytes, we manipulate matrix stiffness in 3D osteocyte culture. We use Gelatin methacryloyl (GelMA) as a popular stiffness customisable 3D cell embedding biomaterial with similar properties to collagen found in bone matrix.⁵ High stiffness environments promote mechanotransduction from greater traction forces placed on osteocyte membrane-matrix adhesions;⁶ mimicking stress experienced in bone loading. We also demonstrate strong viability and osteocyte dendritic morphology of MLO-Y4 cells grown in GelMA. Overall, this research will increase understanding of the role paraspeckles have in bone formation and homeostatic skeletal health, particularly in osteocyte mechanosensation and bone adaption to mechanical loading.