Human angiogenin is a neuroprotective factor and amyotrophic lateral sclerosis associated angiogenin variants affect neurite extension/pathfinding and survival of motor neurons.

Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
Human Molecular Genetics (Impact Factor: 6.68). 02/2008; 17(1):130-49. DOI: 10.1093/hmg/ddm290
Source: PubMed

ABSTRACT Amyotrophic lateral sclerosis (ALS) is a late onset neurodegenerative disorder affecting upper and lower motor neurons (MNs). The molecular mechanisms underlying ALS are poorly understood. Mutations in SOD1 is one of the known causes of ALS but occur only in a very small number of cases of ALS. Interestingly, mutations in human angiogenin (hANG), a member of the ribonuclease A (RNase A) superfamily known to be involved in neovascularization, have been recently reported in patients with ALS, but the effects of these mutations on MN differentiation and survival has not been investigated. We have used the well-characterized pluripotent P19 embryonal carcinoma (EC) cell culture model of neuro-ectodermal differentiation to study the effects of hANG-ALS variants on MN differentiation and survival. Here we report that P19 EC cells induced to differentiate in the presence of hANG and hANG-ALS-associated variants internalize the wild-type and variant proteins. The P19 EC cells differentiate to form neurons but the ability of the neurites to extend and make contacts with neighbouring neurites is compromised when treated with the hANG-ALS variants. In addition, hANG-ALS variants also have a cytotoxic effect on MNs leading to their degeneration. hANG was able to protect neurons from hypoxia-induced cell death, but the variants of hANG implicated in ALS lacked the neuroprotective activity. Our findings show that ANG plays an important role in neurite extension/pathfinding and survival providing a causal link between mutations in hANG and ALS.

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    ABSTRACT: Mutations in the angiogenic factor, angiogenin (ANG), have been identified in patients with both familial and sporadic amyotrophic lateral sclerosis (ALS) and are thought to have a neuroprotective function. Parkinsonism has been noted in kindreds with ANG mutations and variants in the ANG gene have been found to associate with PD in two Caucasian populations. We therefore hypothesized that mutations in ANG may also contribute to idiopathic Parkinson's disease (PD). We sequenced ANG gene in a total of 1498 participants comprising 750 PD patients and 748 age/gender matched controls from Taiwan. We identified one novel synonymous substitution, c.C100T (p.L10L), in a single heterozygous state in one PD patient, which was not observed in controls. The clinical phenotypes and [99mTc]-TORDAT-SPECT images of the p.L10L carrier were similar to that seen in idiopathic PD. In addition, we also identified one common variant, c.T330G (p.G110G, rs11701), which was previously reported to associate with PD risk in Caucasians. However, the frequency of TG/GG genotype was comparable between PD cases and controls (odds ratio: 0.85, 95% confidence interval: 0.29-2.55, P = 0.78). Our results did not support that ANG rs11701 variant is a genetic risk factor for PD in our population. We conclude that mutations in ANG are not a common cause for idiopathic PD.
    PLoS ONE 11/2014; 9(11):e112661. DOI:10.1371/journal.pone.0112661 · 3.53 Impact Factor
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    ABSTRACT: The Angiogenin (ANG) gene is frequently mutated in patients suffering from the neurodegenerative disease - amyotrophic lateral sclerosis (ALS). Most of the ALS-causing mutations in Angiogenin affect either its ribonucleolytic or nuclear translocation activity. Here we report the functional characterization of two previously uncharacterized missense mutations in Angiogenin - D22G and L35P. We predict the nature of loss-of-function(s) in these mutants through our previously established Molecular Dynamics (MD) simulation extended to 100 ns, and show that the predictions are entirely validated through biochemical studies with wild-type and mutated proteins. Based on our studies, we provide a biological explanation for the loss-of-function of D22G-Angiogenin leading to ALS, and suggest that the L35P-Angiogenin mutation would probably cause ALS symptoms in individuals harboring this mutation. Our study thus highlights the strength of MD simulation-based predictions, and suggests that this method can be used for correlating mutations in Angiogenin or other effector proteins with ALS symptoms.
    PLoS ONE 11/2014; 9(11):e111963. DOI:10.1371/journal.pone.0111963 · 3.53 Impact Factor
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