EXPLORING THE ROLE OF CYCLIN-DEPENDENT KINASE-LIKE 5 (CDKL5) IN EXTRACELLULAR VESICLE-MEDIATED NEURONAL COMMUNICATION

Increasing evidence indicate that defective cell proliferation, neural circuit formation and cell-to-cell communication are signature processes of neurodevelopmental disorders (ND). Extracellular vesicles (EVs), nanoparticles secreted by all cell types that carry active signalling molecules (e.g. proteins, RNAs, and miRNAs), have gained critical importance as mediators of non-synaptic communication between brain cells thought to be important for brain and circuit development. However, the role of EVs in brain pathology is still poorly understood.
Here, we disclose that CDKL5, a kinase which mutation causes a severe ND, CDKL5 deficiency disorder (CDD), regulates EV-mediated cell-to-cell communication, by defining their cargo composition. We found that 2-days treatment with EVs isolated from CDKL5 KO neurons (KO-NDEVs) produced profound dendritic and synaptic alterations in primary mouse cortical neurons, while WT-NDEVs treatment rescued the defects shown by cortical CDKL5-KO neurons. To identify the mechanisms of NDEVs effects, we profiled their miRNA content and found that 16 were differentially expressed (DEmiRNAs) between KO and WT. GO enrichment analyses revealed that DEmiRNAs are associated to processes like neuronal organization, synaptic maturation and plasticity. The functional validation of fold-change >1,5 DEmiRNAs is currently ongoing in primary cortical neurons. Supporting the translational potential of our findings, we found that salivary-EVs isolated from CDD patients and neurotypical individuals (n = 20) contained 17 DEmiRNAs involved in neuronal and synaptic processes. This study provides strong in-vitro evidence of CDKL5 role in EV-mediated communication in the brain, motivate the search of EV-based biomarkers for CDD, and opens to future therapeutic options.