Olfactory Stem Cells, a New Cellular Model for Studying Molecular Mechanisms Underlying Familial Dysautonomia

International audienceBackground: Familial dysautonomia (FD) is a hereditary neuropathy caused by mutations in the IKBKAP gene, the most common of which results in variable tissue-specific mRNA splicing with skipping of exon 20. Defective splicing is especially severe in nervous tissue, leading to incomplete development and progressive degeneration of sensory and autonomic neurons. The specificity of neuron loss in FD is poorly understood due to the lack of an appropriate model system. To better understand and modelize the molecular mechanisms of IKBKAP mRNA splicing, we collected human olfactory ecto-mesenchymal stem cells (hOE-MSC) from FD patients. hOE-MSCs have a pluripotent ability to differentiate into various cell lineages, including neurons and glial cells.Methodology/Principal Findings: We confirmed IKBKAP mRNA alternative splicing in FD hOE-MSCs and identified 2 novel spliced isoforms also present in control cells. We observed a significant lower expression of both IKBKAP transcript and IKAP/hELP1 protein in FD cells resulting from the degradation of the transcript isoform skipping exon 20. We localized IKAP/hELP1 in different cell compartments, including the nucleus, which supports multiple roles for that protein. We also investigated cellular pathways altered in FD, at the genome-wide level, and confirmed that cell migration and cytoskeleton reorganization were among the processes altered in FD. Indeed, FD hOE-MSCs exhibit impaired migration compared to control cells. Moreover, we showed that kinetin improved exon 20 inclusion and restores a normal level of IKAP/hELP1 in FD hOE-MSCs. Furthermore, we were able to modify the IKBKAP splicing ratio in FD hOE-MSCs, increasing or reducing the WT (exon 20 inclusion):MU (exon 20 skipping) ratio respectively, either by producing free-floating spheres, or by inducing cells into neural differentiation.Conclusions/Significance: hOE-MSCs isolated from FD patients represent a new approach for modeling FD to better understand genetic expression and possible therapeutic approaches. This model could also be applied to other neurological genetic diseases

Effects of Spaceflight on the Immune System

The immune system belongs to the most affected systems during spaceflight, and sensitivity of cells of the human immune system to reduced gravity has been confirmed in numerous studies in real and simulated microgravity. Immune system dysfunction during spaceflight represents a substantial risk for exploration class mission knowledge about the clinical, cellular, and genetic basis of immune system response, and adaptation to altered gravity will provide key information for appropriate risk management, efficient monitoring, and countermeasures against existing limiting factors for human health and performance during manned exploration of the solar system. In spite of the immune system dysregulation, studies indicate an adaptation reaction of the immune system to the new microgravity environment, at least for the T-cell system, starting after 2 weeks and continuing until 6 months or longer, reflected by cytokine concentrations in blood plasma or in stimulation assays. At the cellular level, rapid adaptation responses could be detected as early as after seconds until minutes in T cells and macrophages. Therefore, adaptive responses of cells and the whole organism could be expected under microgravity and altered gravity in general. Preventive countermeasures should therefore consider support and stabilization of the endogenous adaptation programs. Potential countermeasures for risk mitigation are summarized in this chapter. We assume that the immune systems not only have a significant adaptation potential when challenged with low gravitational environments but also provide interesting preventive and therapeutic options for long-term space missions