FOXO3a Is Broadly Neuroprotective In Vitro and In Vivo against Insults Implicated in Motor Neuron Diseases

Abstract

Aging is a risk factor for the development of adult-onset neurodegenerative diseases. Although some of the molecular pathways regulating longevity and stress resistance in lower organisms are defined (i.e., those activating the transcriptional regulators DAF-16 and HSF-1 in Caenorhabditis elegans), their relevance to mammals and disease susceptibility are unknown. We studied the signaling controlled by the mammalian homolog of DAF-16, FOXO3a, in model systems of motor neuron disease. Neuron death elicited in vitro by excitotoxic insult or the expression of mutant SOD1, mutant p150 glued , or polyQ-expanded androgen receptor was abrogated by expression of nuclear-targeted FOXO3a. We identify a compound [Psammaplysene A (PA)] that increases nuclear localization of FOXO3a in vitro and in vivo and show that PA also protects against these insults in vitro. Administration of PA to invertebrate model systems of neurodegeneration similarly blocked neuron death in a DAF-16/FOXO3a-dependent manner. These results indicate that activation of the DAF-16/ FOXO3a pathway, genetically or pharmacologically, confers protection against the known causes of motor neuron diseases.

Reduced Activity of AMP-Activated Protein Kinase Protects against Genetic Models of Motor Neuron Disease

“…In this report, we confirm that mitochondria from cells expressing mSOD1 have impaired ATP production, and this is associated with activation of the energy sensor AMPK. This observation is consistent with previous literature reporting dysregulation of various metabolic genes in mSOD1 models, including fatty acid synthase, fatty acid transporter (FAT/CD36), glucose transporter 4, p53, FOX03A, mTOR, and nitric oxide synthase, all of which are downstream targets of the AMPK pathway (Gonzalez de Aguilar et al, 2000;Martin, 2000;Lukas et al, 2006;Fergani et al, 2007;Lobsiger et al, 2007;Morimoto et al, 2007;Gonzalez de Aguilar et al, 2008;Martinez et al, 2008;Mojsilovic-Petrovic et al, 2009) (Lim and Kalb, unpublished observations). Furthermore, we show that AMPK activation has adverse effects on genetic models of motor neuron disease.…”

“…When more than one recombinant HSV vector was used, 1.5 l of each viral stock was added, yielding a total of 3 l of viral stocks to 1 ml of media. Previous work has shown that both transgenes are expressed in Ͼ95% of neurons in a nontoxic manner under these circumstances (Mojsilovic-Petrovic et al, 2009). To quantify motor neurons, immunostained cells were counted in four to five randomly selected fields in each coverslip.…”

Proteasome-mediated Proteolysis of the Polyglutamine-expanded Androgen Receptor Is a Late Event in Spinal and Bulbar Muscular Atrophy (SBMA) Pathogenesis

“…Dissociated spinal cord cultures from wild-type mice were differentiated for 3 weeks and then infected with AAV to express full-length human AR (AR24Q or AR111Q) tagged with a C-terminal FLAG epitope. As previously shown for motor neurons expressing untagged polyglutamine-expanded AR (27,29,30), a substantial number of motor neurons died by 8 days of treatment with DHT (Fig. 2D, right panel).…”

“…Primary Dissociated Spinal Cord Cultures and AAV Infection-Dissociated spinal cord cultures were established according to Roy et al (28) with modifications as described (11,29,30). Briefly, spinal cords from non-transgenic 13.5-day-old mouse embryos were dissected on ice in dissection medium (0.1% dextrose, 2% sucrose, 6.8 mM NaCl, 0.27 mM KCl, 8.4 M Na 2 HPO 4 , 11 M KH 2 PO 4 , and 9.9 mM HEPES), pooled, dissociated with trypsin, plated on poly-D-lysine (Sigma)-coated German glass coverslips (Chemglass Life Sciences), and cultured for 3 weeks in glial conditioned medium (minimum essential medium, 3% charcoal-stripped horse serum, 35 mM NaHCO 3 , 0.5% dextrose, 1% N3, 10 nM 2.5S nerve growth factor).…”

FOXO protects against age‐progressive axonal degeneration

“…Similarly, activation of FOXO in mammalian neurons induced cell death (Gilley, Coffer & Ham, 2003; Yuan et al., 2008, 2009). By contrast, constitutively active FOXO protected neurons against excitotoxic and proteotoxic insults (Mojsilovic‐Petrovic et al., 2009). …”