TY  - JOUR
A1  - Simon, Christian M.
A1  - Rauskolb, Stefanie
A1  - Gunnersen, Jennifer M.
A1  - Holtmann, Bettina
A1  - Drepper, Carsten
A1  - Dombert, Benjamin
A1  - Braga, Massimiliano
A1  - Wiese, Stefan
A1  - Jablonka, Sibylle
A1  - Pühringer, Dirk
A1  - Zielasek, Jürgen
A1  - Hoeflich, Andreas
A1  - Silani, Vincenzo
A1  - Wolf, Eckhard
A1  - Kneitz, Susanne
A1  - Sommer, Claudia
A1  - Toyka, Klaus V.
A1  - Sendtner, Michael
T1  - Dysregulated IGFBP5 expression causes axon degeneration and motoneuron loss in diabetic neuropathy
JF  - Acta Neuropathologica
N2  - Diabetic neuropathy (DNP), afflicting sensory and motor nerve fibers, is a major complication in diabetes.The underlying cellular mechanisms of axon degeneration are poorly understood. IGFBP5, an inhibitory binding protein for insulin-like growth factor 1 (IGF1) is highly up-regulated in nerve biopsies of patients with DNP. We investigated the pathogenic relevance of this finding in transgenic mice overexpressing IGFBP5 in motor axons and sensory nerve fibers. These mice develop motor axonopathy and sensory deficits similar to those seen in DNP. Motor axon degeneration was also observed in mice in which the IGF1 receptor(IGF1R) was conditionally depleted in motoneurons, indicating that reduced activity of IGF1 on IGF1R in motoneurons is responsible for the observed effect. These data provide evidence that elevated expression of IGFBP5 in diabetic nerves reduces the availability of IGF1 for IGF1R on motor axons, thus leading to progressive neurodegeneration. Inhibition of IGFBP5 could thus offer novel treatment strategies for DNP.
KW  - Motor nerve biopsy
KW  - Diabetic polyneuropathy
KW  - Neuropathy
KW  - Neurotrophic factors
KW  - Axonal degeneration
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-154569
VL  - 130
SP  - 373
EP  - 387
ER  - 
TY  - JOUR
A1  - Dombert, Benjamin
A1  - Sivadasan, Rajeeve
A1  - Simon, Christian M.
A1  - Jablonka, Sibylle
A1  - Sendtner, Michael
T1  - Presynaptic Localization of Smn and hnRNP R in Axon Terminals of Embryonic and Postnatal Mouse Motoneurons
N2  - Spinal muscular atrophy (SMA) is caused by deficiency of the ubiquitously expressed survival motoneuron (SMN) protein. SMN is crucial component of a complex for the assembly of spliceosomal small nuclear ribonucleoprotein (snRNP) particles. Other cellular functions of SMN are less characterized so far. SMA predominantly affects lower motoneurons, but the cellular basis for this relative specificity is still unknown. In contrast to nonneuronal cells where the protein is mainly localized in perinuclear regions and the nucleus, Smn is also present in dendrites, axons and axonal growth cones of isolated motoneurons in vitro. However, this distribution has not been shown in vivo and it is not clear whether Smn and hnRNP R are also present in presynaptic axon terminals of motoneurons in postnatal mice. Smn also associates with components not included in the classical SMN complex like RNA-binding proteins FUS, TDP43, HuD and hnRNP R which are involved in RNA processing, subcellular localization and translation. We show here that Smn and hnRNP R are present in presynaptic compartments at neuromuscular endplates of embryonic and postnatal mice. Smn and hnRNP R are localized in close proximity to each other in axons and axon terminals both in vitro and in vivo. We also provide new evidence for a direct interaction of Smn and hnRNP R in vitro and in vivo, particularly in the cytosol of motoneurons. These data point to functions of SMN beyond snRNP assembly which could be crucial for recruitment and transport of RNA particles into axons and axon terminals, a mechanism which may contribute to SMA pathogenesis.
KW  - axons
KW  - spinal cord
KW  - cytosol
KW  - DAPI staining
KW  - immunoprecipitation
KW  - recombinant proteins
KW  - protein interactions
KW  - thoracic diaphragm
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113655
ER  -