SUMMARY The primary cause of Huntington’s disease (HD) is expression of huntingtin with a polyglutamine expansion. Despite an absence of consensus on the mechanism(s) of toxicity, diminishing the synthesis of mutant huntingtin will abate toxicity if delivered to the key affected cells. With antisense oligonucleotides (ASOs) that catalyze RNase H-mediated degradation of huntingtin mRNA, we demonstrate that transient infusion into the cerebral spinal fluid of symptomatic HD mouse models not only delays disease progression, but mediates a sustained reversal of disease phenotype that persists longer than the huntingtin knockdown. Reduction of wild type huntingtin, along with mutant huntingtin, produces the same sustained disease reversal. Similar ASO infusion into non-human primates is shown to effectively lower huntingtin in many brain regions targeted by HD pathology. Rather than requiring continuous treatment, our findings establish a therapeutic strategy for sustained HD disease reversal produced by transient ASO-mediated diminution of huntingtin synthesis.

Mutations in the acid β-glucocerebrosidase (GBA1) gene, responsible for the lysosomal storage disorder Gaucher's disease (GD), are the strongest genetic risk factor for Parkinson's disease (PD) known to date. Here we generate induced pluripotent stem cells from subjects with GD and PD harbouring GBA1 mutations, and differentiate them into midbrain dopaminergic neurons followed by enrichment using fluorescence-activated cell sorting. Neurons show a reduction in glucocerebrosidase activity and protein levels, increase in glucosylceramide and α-synuclein levels as well as autophagic and lysosomal defects. Quantitative proteomic profiling reveals an increase of the neuronal calcium-binding protein 2 (NECAB2) in diseased neurons. Mutant neurons show a dysregulation of calcium homeostasis and increased vulnerability to stress responses involving elevation of cytosolic calcium. Importantly, correction of the mutations rescues such pathological phenotypes. These findings provide evidence for a link between GBA1 mutations and complex changes in the autophagic/lysosomal system and intracellular calcium homeostasis, which underlie vulnerability to neurodegeneration.

The adult rat spinal cord contains cells that can proliferate and differentiate into astrocytes and oligodendroglia in situ. Using clonal and subclonal analyses we demonstrate that, in contrast to progenitors isolated from the adult mouse spinal cord with a combination of growth factors, progenitors isolated from the adult rat spinal cord using basic fibroblast growth factor alone display stem cell properties as defined by their multipotentiality and self-renewal. Clonal cultures derived from single founder cells generate neurons, astrocytes, and oligodendrocytes, confirming the multipotent nature of the parent cell. Subcloning analysis showed that after serial passaging, recloning, and expansion, these cells retained multipotentiality, indicating that they are self-renewing. Transplantation of an in vitro-expanded clonal population of cells into the adult rat spinal cord resulted in their differentiation into glial cells only. However, after heterotopic transplantation into the hippocampus, transplanted cells that integrated in the granular cell layer differentiated into cells characteristic of this region, whereas engraftment into other hippocampal regions resulted in the differentiation of cells with astroglial and oligodendroglial phenotypes. The data indicate that clonally expanded, multipotent adult progenitor cells from a non-neurogenic region are not lineage-restricted to their developmental origin but can generate region-specific neurons in vivo when exposed to the appropriate environmental cues.Key words : spinal cord; stem cells; FGF; transplantation; neuroplasticity; adult Most neurogenesis in the mammalian CNS is believed to end in the period just after birth (Nornes and Das, 1974;Altman and Bayer, 1984). However, neurogenesis continues in different regions of the brain of various adult mammalian species (Kaplan and Hinds, 1980;Bayer et al., 1982; Alvarez-Buylla, 1993, 1994;Luskin, 1993). The spinal cord, like most structures of the mammalian brain, belongs to the class of nonrenewable epithelium (Rakic, 1985). However, a small number of cells that line the central canal (Adrian and Walker, 1962;Johansson et al., 1999) remain mitotic. We have demonstrated recently that the adult rat spinal cord contains large numbers of dividing cells in vivo that give rise to glia but not neurons (Horner et al., 2000).Multipotent stem cells that respond to epidermal growth factor (EGF) or basic fibroblast growth factor (FGF-2) have been isolated from both neurogenic (Morshead et al., 1994;Palmer et al., 1997) and non-neurogenic regions of the adult mammalian CNS (Temple and Alvarez-Buylla, 1999). Recent studies indicate that embryonic day 14 mouse striatum or adult subventricular zone (SVZ) contains multipotent stem-like cells that are controlled by FGF-2 or EGF in a regulatable manner (Ciccolini and Svendsen, 1998;Gritti et al., 1999). However, this is not true of adult CNS stem cells from all regions, because a combination of EGF and FGF-2 was necessary to isolate stem cells from the adult mouse spinal cord ,...

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by mutations in the SMN1 gene that result in a deficiency of SMN protein. One approach to treat SMA is to use antisense oligonucleotides (ASOs) to redirect the splicing of a paralogous gene, SMN2, to boost production of functional SMN. Injection of a 2′-O-2-methoxyethyl–modified ASO (ASO-10-27) into the cerebral lateral ventricles of mice with a severe form of SMA resulted in splice-mediated increases in SMN protein and in the number of motor neurons in the spinal cord, which led to improvements in muscle physiology, motor function and survival. Intrathecal infusion of ASO-10-27 into cynomolgus monkeys delivered putative therapeutic levels of the oligonucleotide to all regions of the spinal cord. These data demonstrate that central nervous system–directed ASO therapy is efficacious and that intrathecal infusion may represent a practical route for delivering this therapeutic in the clinic.

Emerging genetic and clinical evidence suggests a link between Gaucher disease and the synucleinopathies Parkinson disease and dementia with Lewy bodies. Here, we provide evidence that a mouse model of Gaucher disease ( Gba1 D409V/D409V ) exhibits characteristics of synucleinopathies, including progressive accumulation of proteinase K-resistant α-synuclein/ubiquitin aggregates in hippocampal neurons and a coincident memory deficit. Analysis of homozygous ( Gba1 D409V/D409V ) and heterozygous ( Gba1 D409V/+ and Gba1 +/− ) Gaucher mice indicated that these pathologies are a result of the combination of a loss of glucocerebrosidase activity and a toxic gain-of-function resulting from expression of the mutant enzyme. Importantly, adeno-associated virus-mediated expression of exogenous glucocerebrosidase injected into the hippocampus of Gba1 D409V/D409V mice ameliorated both the histopathological and memory aberrations. The data support the contention that mutations in GBA1 can cause Parkinson disease-like α-synuclein pathology, and that rescuing brain glucocerebrosidase activity might represent a therapeutic strategy for GBA1 -associated synucleinopathies.