Antisense peptide nucleic acid‐mediated knockdown of the p75 neurotrophin receptor delays motor neuron disease in mutant SOD1 transgenic mice

Abstract

Re-expression of the death-signalling p75 neurotrophin receptor (p75 NTR ) is associated with injury and neurodegeneration in the adult nervous system. The induction of p75 NTR expression in mature degenerating spinal motor neurons of humans and transgenic mice with amyotrophic lateral sclerosis (ALS) suggests a role of p75 NTR in the progression of motor neuron disease (MND). In this study, we designed, synthesized and evaluated novel antisense peptide nucleic acid (PNA) constructs targeting p75 NTR as a potential gene knockdown therapeutic strategy for ALS. An 11-mer antisense PNA directed at the initiation codon, but not downstream gene sequences, dose-dependently inhibited p75 NTR expression and death-signalling by nerve growth factor (NGF) in Schwann cell cultures. Antisense phosphorothioate oligonucleotide (PS-ODN) sequences used for comparison failed to confer such inhibitory activity. Systemic intraperitoneal administration of this antisense PNA to mutant superoxide dismutase 1 (SOD1 G93A ) transgenic mice significantly delayed locomotor impairment and mortality compared with mice injected with nonsense or scrambled PNA sequences. Reductions in p75 NTR expression and subsequent caspase-3 activation in spinal cords were consistent with increased survival in antisense PNA-treated mice. The uptake of fluorescent-labelled antisense PNA in the nervous system of transgenic mice was also confirmed. This study suggests that p75 NTR may be a promising antisense target in the treatment of ALS. Keywords: amyotrophic lateral sclerosis, antisense, motor neuron, p75 neurotrophin receptor, peptide nucleic acid, superoxide dismutase 1.

Astrocyte and Muscle-Derived Secreted Factors Differentially Regulate Motoneuron Survival

“…p75 NTR , a promiscuous receptor for multiple neurotrophins, is implicated in both the survival and death of MNs and is highly expressed in this population during development and in response to injury (McKay et al, 1996;Ferri et al, 1998;Wiese et al, 1999;Boyd and Gordon, 2001;Turner et al, 2003;Pehar et al, 2004;Cassina et al, 2005). Moreover, we verified p75 NTR expression in MNs after treatment with ACM and MCM (data not shown).…”

Pro-NGF secreted by astrocytes promotes motor neuron cell death

“…In amyotrophic lateral sclerosis, p75 immuno-reactivity is increased in spinal motor neurons (Seeburger et al 1993;Copray et al 2003) while both TrkA and TkB are absent (Seeburger et al 1993). In a mouse model of the disease, the onset of degeneration was delayed in p75-null female mice (Kust et al 2003) and antisense-mediated knockdown of p75 in adult animals delayed disease progression (Turner et al 2003).…”

A Role for the p75 Neurotrophin Receptor in Axonal Degeneration and Apoptosis Induced by Oxidative Stress

“…NTR has been linked to neurodegeneration occurring in models of Alzheimer disease (20), amyotrophic lateral sclerosis (21), and ischemia (22)(23)(24)(25). Therefore, p75 NTR appears to function as a stress-activated receptor that promotes degeneration in response to neuronal injury.…”