Background: Proteins targeted by the Ubiquitin Proteasome System (UPS) are identified for degradation by the proteasome, which has been implicated in the development of neuro-degenerative diseases. Major histocompatibility complex (MHC) molecules present peptides broken down by the proteasome and are involved in neuronal plasticity, regulating synapse number and axon regeneration in the central or peripheral nervous system during develop-ment and in brain diseases. The mechanisms governing these effects are mostly unknown, but evidence from different compartments of the cerebral cortex indicates the presence of im-mune-like MHC receptors in the central nervous system. Methods: We have used human induced pluripotent stem cells (iPSC) differentiated to neural stem cells and then to motor neurons as a developmental model to better understand the structure of the proteasome in developing motor neurons. We perform a proteomic analysis of starting human skin fibroblasts, their matching iPSC, differentiated neural stem cells and motor neurons that highlighted significant differences in the constitutive proteasome and immunoproteasome subunits during development towards motor neurons from iPSC. Results: Proteomic analysis showed that the catalytic proteasome subunits expressed in fi-broblasts differ to those in neural stem cells and motor neurons. Western blot analysis con-firmed the proteomic data, particularly the decreased expression of Beta5i (PSMB8) subunit immunoproteasome. Conclusion: The constitutive proteasome subunits are upregulated in iPSC from HFF and the immunoproteasome subunit beta 5i expression is higher in MN than NSC suggesting a im-munoproteasome phenotype in MN. The immunoproteasome may have implications on motor neuron development and neurodevelopmental diseases that warrants further investi-gation.

The adipose tissue is responsible for fat storage and is the major producer of exosomes. Biological content transported by the exosomes provides information, such as immunometabolic alterations. This study aimed to isolate whole exosomes from plasma and supernatant of differentiated 3T3-L1 cells using three isolation techniques. Plasma from 120 individuals categorized by body adipose tissue proportion and differentiated 3T3-L1 cells were used in this study. The exosome isolation techniques were differential centrifugation (DC), size exclusion chromatography (SEC), and a commercial kit (Invitrogen), and characterized by cryo-TEM, TEM, and western blot for the tetraspanins CD9 and CD81. In the three isolation techniques, cryo-TEM and TEM analysis showed similar quality, quantity, and morphology of exosomes; at the same time, no difference was observed between individuals categorized by proportion of body fat. According to our results, the concentration of the circulating exosomes is not different between normal and high-fat percentage individuals, but rather their composition. The SEC and kit commercial proved that compile with most of the advantages of an exosome isolation technique, nerveless we emphasize the importance of selecting the appropriate methodology depending on the specific research objectives.