Angiogenin in Parkinson Disease Models: Role of Akt Phosphorylation and Evaluation of AAV-Mediated Angiogenin Expression in MPTP Treated Mice

Trent U Steidinger,Talene A Yacoubian,Huiping Ding,David G Standaert,Sunny R Slone,Malú G Tansey

doi:10.1371/journal.pone.0056092

Trent U Steidinger, Talene A Yacoubian + Show 4 more

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https://doi.org/10.1371/journal.pone.0056092

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Journal: PloS one	Publication Date: Feb 7, 2013
Citations: 62	License type: CC BY 4.0

Affiliation: University of Alabama at Birmingham

Abstract

The angiogenic factor, angiogenin, has been recently linked to both Amyotrophic Lateral Sclerosis (ALS) and Parkinson Disease (PD). We have recently shown that endogenous angiogenin levels are dramatically reduced in an alpha-synuclein mouse model of PD and that exogenous angiogenin protects against cell loss in neurotoxin-based cellular models of PD. Here, we extend our studies to examine whether activation of the prosurvival Akt pathway is required for angiogenin's neuroprotective effects against 1-methyl-4-phenylpyridinium (MPP+), as observed in ALS models, and to test the effect of virally-mediated overexpression of angiogenin in an in vivo PD model. Using a dominant negative Akt construct, we demonstrate that inhibition of the Akt pathway does not reduce the protective effect of angiogenin against MPP+ toxicity in the dopaminergic SH-SY5Y cell line. Furthermore, an ALS-associated mutant of angiogenin, K40I, which fails to induce Akt phosphorylation, was similar to wildtype angiogenin in protection against MPP+. These results confirm previous work showing neuroprotective effects of angiogenin against MPP+, and indicate that Akt is not required for this protective effect. We also investigated whether adeno-associated viral serotype 2 (AAV2)-mediated overexpression of angiogenin protects against dopaminergic neuron loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model. We found that angiogenin overexpression using this approach does not reduce the MPTP-induced degeneration of dopaminergic cells in the substantia nigra, nor limit the depletion of dopamine and its metabolites in the striatum. Together, these findings extend the evidence for protective effects of angiogenin in vitro, but also suggest that further study of in vivo models is required to translate these effects into meaningful therapies.

Highlights

The potent angiogenic factor, angiogenin, has recently been associated with neurodegenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS) and Parkinson Disease (PD) [1,2]
We first show that this dominant negative Akt (DN-Akt) eliminates Akt phosphorylation in response to Insulin Growth Factor in cells transfected with Dominant negative (DN)-Akt compared to empty vector (Fig. 1a)
Our results indicate that angiogenin is still protective against MPP+ in the presence of DN-Akt (Fig. 1b,c), suggesting that Akt activation is not critical for angiogenin’s effect in the SH-SY5Y dopaminergic cell line

Summary

Introduction

The potent angiogenic factor, angiogenin, has recently been associated with neurodegenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS) and Parkinson Disease (PD) [1,2]. Wildtype angiogenin has been shown to reduce motoneuron cell death in response to hypoxia, serum deprivation, ER stress, and excitotoxicity, while mutant forms of angiogenin associated with ALS fail to reduce toxicity in these models [10,11,12]. Our lab previously demonstrated a robust down-regulation of angiogenin expression in transgenic mice overexpressing human alphasynuclein, a mouse model of PD [13,14]. We demonstrated that exogenous angiogenin reduced toxicity by rotenone and 1methyl-4-phenylpyridine (MPP+) in neuroblastoma cell lines [14]

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