@phdthesis{Ghanawi2022,
  author    = {Ghanawi, Hanaa},
  title     = {Loss of full-length hnRNP R isoform impairs DNA damage response in motoneurons by inhibiting Yb1 recruitment to Chromatin},
  doi       = {10.25972/OPUS-25849},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258492},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Motoneurons are highly compartmentalized cells with very long extensions that separate their nerve terminals from cell bodies. To maintain their extensive morphological complexity and protect their cellular integrity from neurotoxic stresses, neurons rely on the functions of RNA-binding proteins. One such protein is hnRNP R, a multifunctional protein with a plethora of roles related to RNA metabolism that comes into play in the nervous system. hnRNP R is localized mainly in the nucleus but also exists in the cytoplasm and axons of motoneurons. Increasing in vitro evidence indicates a potential function of hnRNP R in the development and maintenance of motoneurons by regulating axon growth and axonal RNA transport. Additionally, hnRNP R interacts with several proteins involved in motoneuron diseases. Hnrnpr pre-mRNA undergoes alternative splicing to produce transcripts encoding two protein isoforms: a full-length protein (hnRNP R-FL) and a shorter form lacking the N-terminal acidic domain (hnRNP R-ΔN). While the neuronal defects produced by total hnRNP R depletion have been investigated before, the contribution of individual isoforms towards such functions has remained mostly unknown. In this study, we showed that while both isoforms are expressed across multiple tissues, the full-length isoform is particularly abundant in the nervous system. We generated a mouse model for selective knockout of the full-length hnRNP R isoform (Hnrnprtm1a/tm1a) and found that the hnRNP R-∆N isoform remains expressed in these mice and is upregulated in a compensatory post-transcriptional process. We found that the truncated isoform is sufficient to support subcellular RNA transport related to axon growth in primary motoneurons. However, Hnrnprtm1a/tm1a mice show defects in DNA damage repair after exposure to γ-irradiation and etoposide. Knock down of both hnRNP R isoforms showed a similar extent of DNA damage as for motoneurons depleted of just full-length hnRNP R. Rescue experiments showed that expression of full-length hnRNP R but not of hnRNP R-ΔN can restore DNA damage repair when endogenous hnRNP R is depleted. By performing subcellular fractionation, we found that hnRNP R associates with chromatin independently from its association with pre-mRNA. Interestingly, we show that hnRNP R interacts with phosphorylated histone H2AX (γ-H2AX), following DNA damage. Proteomics analysis identifies the multifunctional protein Y-box binding protein 1 (Yb1) as one of the top interacting partners of hnRNP R. Similar to loss of full-length hnRNP R, DNA damage repair was impaired upon knockdown of Yb1 in motoneurons. Finally, we show that following exposure to γ-irradiation, Yb1 is recruited to the chromatin where it interacts with γ-H2AX, a mechanism that is dependent on the full-length hnRNP R. Taken together, this study describes a novel function of the full-length isoform of hnRNP R in maintaining the genomic integrity of motoneurons and provides new mechanistic insights into its function in DNA damage response.},
  language  = {en}
}
@article{GresleAlexandrouWuetal.2012,
  author    = {Gresle, Melissa M. and Alexandrou, Estella and Wu, Qizhu and Egan, Gary and Jokubaitis, Vilija and Ayers, Margaret and Jonas, Anna and Doherty, William and Friedhuber, Anna and Shaw, Gerry and Sendtner, Michael and Emery, Ben and Kilpatrick, Trevor and Butzkueven, Helmut},
  title     = {Leukemia Inhibitory Factor Protects Axons in Experimental Autoimmune Encephalomyelitis via an Oligodendrocyte-Independent Mechanism},
  series = {PLoS One},
  volume    = {7},
  journal   = {PLoS One},
  number    = {10},
  doi       = {10.1371/journal.pone.0047379},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134617},
  pages     = {e47379},
  year      = {2012},
  abstract  = {Leukemia inhibitory factor (LIF) and Ciliary Neurotrophic factor (CNTF) are members of the interleukin-6 family of cytokines, defined by use of the gp130 molecule as an obligate receptor. In the murine experimental autoimmune encephalomyelitis (EAE) model, antagonism of LIF and genetic deletion of CNTF worsen disease. The potential mechanism of action of these cytokines in EAE is complex, as gp130 is expressed by all neural cells, and could involve immuno-modulation, reduction of oligodendrocyte injury, neuronal protection, or a combination of these actions. In this study we aim to investigate whether the beneficial effects of CNTF/LIF signalling in EAE are associated with axonal protection; and whether this requires signalling through oligodendrocytes. We induced MOG\(_{35-55}\) EAE in CNTF, LIF and double knockout mice. On a CNTF null background, LIF knockout was associated with increased EAE severity (EAE grade 2.1\(\pm\)0.14 vs 2.6\(\pm\)0.19; P<0.05). These mice also showed increased axonal damage relative to LIF heterozygous mice, as indicated by decreased optic nerve parallel diffusivity on MRI (1540\(\pm\)207 \(\mu\)m\(^2\)-/s vs 1310\(\pm\)175 \(\mu\)m\(^2\)-/s; P<0.05), and optic nerve (-12.5\%) and spinal cord (-16\%) axon densities; and increased serum neurofilament-H levels (2.5 fold increase). No differences in inflammatory cell numbers or peripheral auto-immune T-cell priming were evident. Oligodendrocyte-targeted gp130 knockout mice showed that disruption of CNTF/LIF signalling in these cells has no effect on acute EAE severity. These studies demonstrate that endogenous CNTF and LIF act centrally to protect axons from acute inflammatory destruction via an oligodendrocyte-independent mechanism.},
  language  = {en}
}
@article{WetzelJablonkaBlum2013,
  author    = {Wetzel, Andrea and Jablonka, Sibylle and Blum, Robert},
  title     = {Cell-autonomous axon growth of young motoneurons is triggered by a voltage-gated sodium channel},
  series = {Channels (Austin)},
  volume    = {7},
  journal   = {Channels (Austin)},
  number    = {1},
  doi       = {10.4161/chan.23153},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132586},
  pages     = {51-56},
  year      = {2013},
  abstract  = {Spontaneous electrical activity preceding synapse formation contributes to the precise regulation of neuronal development. Examining the origins of spontaneous activity revealed roles for neurotransmitters that depolarize neurons and activate ion channels. Recently, we identified a new molecular mechanism underlying fluctuations in spontaneous neuronal excitability. We found that embryonic motoneurons with a genetic loss of the low-threshold sodium channel Na\(_V\)1.9 show fewer fluctuations in intracellular calcium in axonal compartments and growth cones than wild-type littermates. As a consequence, axon growth of Na\(_V\)1.9-deficient motoneurons in cell culture is drastically reduced while dendritic growth and cell survival are not affected. Interestingly, Na\(_V\)1.9 function is observed under conditions that would hardly allow a ligand- or neurotransmitter-dependent depolarization. Thus, Na\(_V\)1.9 may serve as a cell-autonomous trigger for neuronal excitation. In this addendum, we discuss a model for the interplay between cell-autonomous local neuronal activity and local cytoskeleton dynamics in growth cone function.},
  language  = {en}
}
@article{KriegerMetzgerJablonka2014,
  author    = {Krieger, Frank and Metzger, Friedrich and Jablonka, Sibylle},
  title     = {Differentiation defects in primary motoneurons from a SMARD1 mouse model that are insensitive to treatment with low dose PEGylated IGF1},
  series = {Rare Diseases},
  volume    = {2},
  journal   = {Rare Diseases},
  number    = {e29415},
  issn      = {2167-5511},
  doi       = {10.4161/rdis.29415},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120610},
  year      = {2014},
  abstract  = {Muscle atrophy and diaphragmatic palsy are the clinical characteristics of spinal muscular atrophy with respiratory distress type 1 (SMARD1), and are well represented in the neuromuscular degeneration \((Nmd^{2J})\) mouse, modeling the juvenile form of SMARD1. Both in humans and mice mutations in the IGHMBP2 gene lead to motoneuron degeneration. We could previously demonstrate that treatment with a polyethylene glycol-coupled variant of IGF1 (PEG-IGF1) improves motor functions accompanied by reduced fiber degeneration in the gastrocnemius muscle and the diaphragm, but has no beneficial effect on motoneuron survival. These data raised the question which cell autonomous disease mechanisms contribute to dysfunction and loss of Ighmbp2-deficient motoneurons. An analysis of primary Ighmbp2-deficient motoneurons exhibited differentiation deficits such as reduced spontaneous \(Ca^{2+}\) transients and altered axon elongation, which was not compensated by PEG-IGF1. This points to an IGF1 independent mechanism of motoneuron degeneration that deserves treatment approaches in addition to IGF1.},
  language  = {en}
}
@misc{SendtnerArakawaStoecklietal.1991,
  author    = {Sendtner, Michael and Arakawa, Yoshihiro and St{\"o}ckli, Kurt A. and Kreutzberg, Georg W. and Thoenen, Hans},
  title     = {Effect of ciliary neurotrophic factor (CNTF) on motoneuron survival},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-33048},
  year      = {1991},
  abstract  = {We have demonstrated that the extensive degeneration of motoneurons in the rat facial nucleus after transection of the facial nerve in newborn rats can be prevented by local ciliary neurotrophic factor (CNTF) administration. CNTF differs distinctly from known neurotrophic molecules such as NGF, BDNF and NT-3 in both its molecular characteristics (CNTF is a cytosolic rather than a secretory molecule) and its broad spectrum of biological activities. CNTF is expressed selectively by Schwann cells and astrocytes of the peripheral and central nervous system, respectively, but not by target tissues of the great variety of CNTF -responsive neurons. CNTF mRNA is not detectable by Northern blot or PCR analysis during embryonic development and immediately after birth. However, during the second post-natal week, a more than 30-fold increase in CNTF mRNA and pro tein occurs in the sciatic nerve. Since the period of low CNTF levels in peripheral nerves coincides with that of high vulnerability of motoneurons (i.e. axonallesion results in degeneration of motoneuron cell bodies), insufficient availability of CNTF may be the reason for the rate of lesioninduced cell death of early post-natal motoneurons. Highly enriched embryonic chick motoneurons in culture are supported at survival rates higher than 60\% by CNTF, even in single cell cultures, indicating that CNTF acts directly on motoneurons. In contrast to CNTF, the members of the neurotrophin gene family (NGF, BDNF and NT-3) do not support the survival of motoneurons in culture. However, aFGF and bFGF show distinct survival activities which are additive to those of CNTF, resulting in the survival of virtually all motoneurons cultured in the presence of CNTF and bFGF.},
  language  = {en}
}