Role of the Cellular Prion Protein in hippocampal neurotransmission, learning and memory
Andreu Matamoros, Molecular and cellular neurobiotechnology
MisfoldedCellular Prion protein (PrPC) was described as the causative agent of the transmissible spongiform encephalopathies (TSEs), independently of its origin (sporadic, iatrogenic or genetic). PrPC is present at the synaptic terminal, especially in the cerebral cortex including the hippocampus. It is involved in numerous cellular processes: cell proliferation and differentiation, copper homeostasis and cell signaling, among others. Recently has been demonstrated that most of these functions are based in misinterpretation of the mice models and need to be reevaluated. On the other hand, PrPC protein levels are decreased in TSEs. This opened a new insight in the study of TSEs: understanding the pathology not just as a gain of function due to the prion aggregation, but as a loss of function due to the reduction of PrPC.
Our goal is to elucidate the role of PrPC in hippocampal circuitry and its derived functions (i.e. learning and memory) using a new PrPC knockout mice (ZH3). Spontaneous firing and network formation are monitored with Calcium imaging in hippocampus primary cultures. Object Recognition Test and Skinner’s Test are performed to evaluate memory and learning in ZH3 mice. LTP and evocated potentials are also measured in CA3-CA1 connection in vivo. Glutamate neurotransmission is evaluated behaviourally and electrophysiologycally using kainate administration. Finally, mRNA from ZH3 mice hippocampus has been sequenced to identify differential gene expression compared to Wt mice.
Dissecting the role of PrPC in hippocampus neurotransmission will allow us to better understand alterations in the brain of TSEs patients.
Paving the way towards an in-vitro 3D mechanosensory-motor circuit on a chip
Maider Badiola, Nanobioengineering
Neuromuscular diseases (NMD) are neurological disorders affecting muscles and their control through nervous system. They often involve afferent and efferent pathways of the Peripheral Nervous System, and their effects might be reflected in the mechanosensory-motor circuit at different cellular levels (including sensory and motor neurons, glia and muscle dysfunctions), and in the connexion among them.
The aim of this research is to create an in-vitro model to mimic the 3D microenvironment of a neural circuit for locomotion to understand and find treatments for NMDs. To that end, organ-on-a-chip technologies are used for the integration of sensorial and motor neural components together with a functional muscular unit.
For that purpose, we first fabricated a compartmentalised microfluidic device in PDMS using soft lithography techniques. Then the afferent and efferent pathways of the Peripheral Nervous System were mimicked in 2D culturing primary neurons involved in the locomotion circuit (motoneurons and dorsal root ganglia) with Schwann cells in the microdevice.
But 2D cultures offer many limitations compared to 3D, and the assessment of the afferent pathway separately often means a complication. Optogenetics technique can be used in skeletal muscle to induce contraction, mimicking a natural innervation to some length and facilitating the study of the afferent pathway separately. Therefore, we propose a study model where primary spinal motor- or dorsal root ganglia sensory- neurons are cultured in 3D in different compartments together with optogenetically sensitive myocytes (a channelrhodopsin-2 positive cell line). This could make possible to evaluate the functionality of efferent and afferent pathways separately.
This study provides the basis for future steps towards NMD in-vitro study models.