@article{KarleSchueleKlebeetal.2013, author = {Karle, Kathrin N. and Sch{\"u}le, Rebecca and Klebe, Stephan and Otto, Susanne and Frischholz, Christian and Liepelt-Scarfone, Inga and Sch{\"o}ls, Ludger}, title = {Electrophysiological characterisation of motor and sensory tracts in patients with hereditary spastic paraplegia (HSP)}, series = {Orphanet Journal of Rare Diseases}, volume = {8}, journal = {Orphanet Journal of Rare Diseases}, number = {158}, issn = {1750-1172}, doi = {10.1186/1750-1172-8-158}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124763}, year = {2013}, abstract = {Background: Hereditary spastic paraplegias (HSPs) are characterised by lower limb spasticity due to degeneration of the corticospinal tract. We set out for an electrophysiological characterisation of motor and sensory tracts in patients with HSP. Methods: We clinically and electrophysiologically examined a cohort of 128 patients with genetically confirmed or clinically probable HSP. Motor evoked potentials (MEPs) to arms and legs, somato-sensory evoked potentials of median and tibial nerves, and nerve conduction studies of tibial, ulnar, sural, and radial nerves were assessed. Results: Whereas all patients showed clinical signs of spastic paraparesis, MEPs were normal in 27\% of patients and revealed a broad spectrum with axonal or demyelinating features in the others. This heterogeneity can at least in part be explained by different underlying genotypes, hinting for distinct pathomechanisms in HSP subtypes. In the largest subgroup, SPG4, an axonal type of damage was evident. Comprehensive electrophysiological testing disclosed a more widespread affection of long fibre tracts involving peripheral nerves and the sensory system in 40\%, respectively. Electrophysiological abnormalities correlated with the severity of clinical symptoms. Conclusions: Whereas HSP is primarily considered as an upper motoneuron disorder, our data suggest a more widespread affection of motor and sensory tracts in the central and peripheral nervous system as a common finding in HSP. The distribution patterns of electrophysiological abnormalities were associated with distinct HSP genotypes and could reflect different underlying pathomechanisms. Electrophysiological measures are independent of symptomatic treatment and may therefore serve as a reliable biomarker in upcoming HSP trials.}, language = {en} } @article{NorrmenFigliaLebrunJulienetal.2014, author = {Norrmen, Camilla and Figlia, Gianluca and Lebrun-Julien, Frederic and Pereira, Jorge A. and Tr{\"o}tzm{\"u}ller, Martin and K{\"o}feler, Harald C. and Rantanen, Ville and Wessig, Carsten and van Deijk, Anne-Lieke F. and Smit, August B. and Verheijen, Mark H. G. and R{\"u}egg, Markus A. and Hall, Michael N. and Suter, Ueli}, title = {mTORC1 Controls PNS Myelination along the mTORC1-RXR gamma-SREBP-Lipid Biosynthesis Axis in Schwann Cells}, series = {Cell Reports}, volume = {9}, journal = {Cell Reports}, number = {2}, issn = {2211-1247}, doi = {10.1016/j.celrep.2014.09.001}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-114847}, pages = {646-660}, year = {2014}, abstract = {Myelin formation during peripheral nervous system (PNS) development, and reformation after injury and in disease, requires multiple intrinsic and extrinsic signals. Akt/mTOR signaling has emerged as a major player involved, but the molecular mechanisms and downstream effectors are virtually unknown. Here, we have used Schwann-cell-specific conditional gene ablation of raptor and rictor, which encode essential components of the mTOR complexes 1 (mTORC1) and 2 (mTORC2), respectively, to demonstrate that mTORC1 controls PNS myelination during development. In this process, mTORC1 regulates lipid biosynthesis via sterol regulatory element-binding proteins (SREBPs). This course of action is mediated by the nuclear receptor RXRg, which transcriptionally regulates SREBP1c downstream of mTORC1. Absence of mTORC1 causes delayed myelination initiation as well as hypomyelination, together with abnormal lipid composition and decreased nerve conduction velocity. Thus, we have identified the mTORC1-RXR gamma-SREBP axis controlling lipid biosynthesis as a major contributor to proper peripheral nerve function.}, language = {en} }