Methods for specific gene silencing have advanced as far as clinical trials, but a similar set of tools does not exist for increasing gene expression. Modarresi et al. demonstrate gene-specific upregulation in vivo by treating mice with oligonucleotides that inhibit the function of natural antisense transcripts. The ability to specifically upregulate genes in vivo holds great therapeutic promise. Here we show that inhibition or degradation of natural antisense transcripts (NATs) by single-stranded oligonucleotides or siRNAs can transiently and reversibly upregulate locus-specific gene expression. Brain-derived neurotrophic factor (BDNF) is normally repressed by a conserved noncoding antisense RNA transcript, BDNF-AS. Inhibition of this transcript upregulates BDNF mRNA by two- to sevenfold, alters chromatin marks at the BDNF locus, leads to increased protein levels and induces neuronal outgrowth and differentiation both in vitro and in vivo. We also show that inhibition of NATs leads to increases in glial-derived neurotrophic factor (GDNF) and ephrin receptor B2 (EPHB2) mRNA. Our data suggest that pharmacological approaches targeting NATs can confer locus-specific gene upregulation effects.

N -methyl- d -aspartate (NMDA) glutamate receptors are regulators of fast neurotransmission and synaptic plasticity in the brain. Disruption of NMDA-mediated glutamate signaling has been linked to behavioral deficits displayed in psychiatric disorders such as schizophrenia. Recently, noncoding RNA molecules such as microRNAs (miRNAs) have emerged as critical regulators of neuronal functions. Here we show that pharmacological (dizocilpine) or genetic (NR1 hypomorphism) disruption of NMDA receptor signaling reduces levels of a brain-specific miRNA, miR-219, in the prefrontal cortex (PFC) of mice. Consistent with a role for miR-219 in NMDA receptor signaling, we identify calcium/calmodulin-dependent protein kinase II γ subunit (CaMKIIγ), a component of the NMDA receptor signaling cascade, as a target of miR-219. In vivo inhibition of miR-219 by specific antimiR in the murine brain significantly modulated behavioral responses associated with disrupted NMDA receptor transmission. Furthermore, pretreatment with the antipsychotic drugs haloperidol and clozapine prevented dizocilpine-induced effects on miR-219. Taken together, these data support an integral role for miR-219 in the expression of behavioral aberrations associated with NMDA receptor hypofunction.

The adult mammalian brain contains neural stem cells (NSCs) with self-renewal and multilineage potential in the hippocampus and subventricular zone. However, neurogenesis from these areas does not compensate for neuronal loss in age-related neurodegenerative disorders such as Alzheimer's disease (AD). To test whether an impairment of neurogenesis could contribute to the pathogenesis of AD, we examined the effects of amyloid-β peptide (Aβ) on the survival and neuronal differentiation of cultured NSCs from striatum and hippocampus. We show that Aβ peptide does not impair the neurogenic rate in NSC progeny, but that it increases the total number of neurons in vitro in a dose-dependent manner. The neurogenic effect of Aβ peptide is not dependent on soluble factors released from the NSC progeny. Neurogenesis is induced by Aβ42 and not Aβ40 or Aβ 25-35, and the activity appears to be a property of Aβ oligomers and not fibrils.

Background. Alzheimer′s disease (AD) is a devastating neurological disorder and the main cause of dementia in the elderly population worldwide. Adult neurogenesis appears to be upregulated very early in AD pathogenesis in response to some specific aggregates of beta‐amyloid (Aβ) peptides, exhausting the neuronal stem cell pools in the brain. Previously, we characterized a conserved nonprotein‐coding antisense transcript for β‐secretase‐1 (BACE1), a critical enzyme in AD pathophysiology. We showed that the BACE1‐antisense transcript (BACE1‐AS) is markedly upregulated in brain samples from AD patients and promotes the stability of the (sense) BACE1 transcript. In the current paper, we examine the relationship between BACE1, BACE1‐AS, adult neurogenesis markers, and amyloid plaque formation in amyloid precursor protein (APP) transgenic mice (Tg‐19959) of various ages. Results. Consistent with previous publications in other APP overexpressing mouse models, we found adult neurogenesis markers to be noticeably upregulated in Tg‐19959 mice very early in the development of the disease. Knockdown of either one of BACE1 or BACE1‐AS transcripts by continuous infusion of locked nucleic acid‐ (LNA‐) modified siRNAs into the third ventricle over the period of two weeks caused concordant downregulation of both transcripts in Tg‐19959 mice. Downregulation of BACE1 mRNA was followed by reduction of BACE1 protein and insoluble Aβ. Modulation of BACE1 and BACE1‐AS transcripts also altered oligomeric Aβ aggregation pattern, which was in turn associated with an increase in neurogenesis markers at the RNA and protein level. Conclusion. We found alterations in the RNA and protein concentrations of several adult neurogenesis markers, as well as non‐protein‐coding BACE1‐AS transcripts, in parallel with the course of β‐amyloid synthesis and aggregation in the brain of Tg15999 mice. In addition, by knocking down BACE1 or BACE1‐AS (thereby reducing Aβ production and plaque deposition), we were able to modulate expression of these neurogenesis markers. Our findings suggest a distortion of adult neurogenesis that is associated with Aβ production very early in amyloid pathogenesis. We believe that these alterations, at the molecular level, could prove useful as novel therapeutic targets and/or as early biomarkers of AD.

Neurofilament light gene mutations have been linked to a subset of patients with Charcot‐Marie‐Tooth disease, the most common inherited motor and sensory neuropathy. We have previously shown that Charcot‐Marie‐Tooth‐linked mutant neurofilament light assembles abnormally in non‐neuronal cells. In this study, we have characterized the effects of expression of mutant neurofilament light proteins on axonal transport in a neuronal cell culture model. We demonstrated that the Charcot‐Marie‐Tooth‐linked neurofilament light mutations: (i) affect the axonal transport of mutant neurofilaments; (ii) have a dominant‐negative effect on the transport of wild‐type neurofilaments; (iii) affect the transport of mitochondria and the anterograde axonal transport marker human amyloid precursor protein; (iv) result in alterations of retrograde axonal transport and (v) cause fragmentation of the Golgi apparatus. Increased neuritic degeneration was observed in neuronal cells overexpressing neurofilament light mutants. Our results suggest that these generalized axonal transport defects could be responsible for the neuropathy in Charcot‐Marie‐Tooth disease.

Neural stem cells proliferate in liquid culture as cell clusters (neurospheres). This study was undertaken to characterize the epidermal growth factor (EGF)-expanded free-floating neurospheres derived from rat fetal striatum. We examined the ultrastructural and antigenic characteristics of these spheres. They consisted of two cell types, electron-dense and electron-lucent cells. Lucent cells were immunopositive to actin, vimentin, and nestin, whereas dense cells were immunopositive to actin, weakly positive to vimentin, and nestin-negative. Neurospheres contained healthy, apoptotic, and necrotic cells. Healthy cells were attached to each other by adherens junctions. They showed many pseudopodia and occasionally a single cilium. Sphere cells showed phagocytic capability because healthy cells phagocytosed the cell debris derived from dead cells in a particular process that involves the engulfment of dying cells by cell processes from healthy cells. Sphere cells showed a cytoplasmic and a nuclear pool of fibroblast growth factor (FGF) receptors. They expressed E- and N-cadherin, α- and β-catenin, EGF receptor, and a specific subset of FGF receptors. Because sphere cells expressed this factor in the absence of exogenous FGF-2, we propose that they are able to synthesize FGF-2.