New Synthetic 3-Benzoyl-5-Hydroxy-2H-Chromen-2-One (LM-031) Inhibits Polyglutamine Aggregation and Promotes Neurite Outgrowth through Enhancement of CREB, NRF2, and Reduction of AMPKα in SCA17 Cell Models.

Chiung-Mei Chen,Wan-Ling Chen,Guey-Jen Lee-Chen,Te-Hsien Lin,Shu-Ting Yang,Wenwei Lin,Shu-Mei Yang,Chih-Ying Chao,Kuo-Hsuan Chang,Yih-Ru Wu

doi:10.1155/2020/3129497

Abstract

Spinocerebellar ataxia type 17 (SCA17) is caused by a CAG/CAA expansion mutation encoding an expanded polyglutamine (polyQ) tract in TATA-box binding protein (TBP), a general transcription initiation factor. Suppression of cAMP-responsive element binding protein- (CREB-) dependent transcription, impaired nuclear factor erythroid 2-related factor 2 (NRF2) signaling, and interaction of AMP-activated protein kinase (AMPK) with increased oxidative stress have been implicated to be involved in pathogenic mechanisms of polyQ-mediated diseases. In this study, we demonstrated decreased pCREB and NRF2 and activated AMPK contributing to neurotoxicity in SCA17 SH-SY5Y cells. We also showed that licochalcone A and the related in-house derivative compound 3-benzoyl-5-hydroxy-2H-chromen-2-one (LM-031) exhibited antiaggregation, antioxidative, antiapoptosis, and neuroprotective effects in TBP/Q79-GFP-expressing cell models. LM-031 and licochalcone A exerted neuroprotective effects by upregulating pCREB and its downstream genes, BCL2 and GADD45B, and enhancing NRF2. Furthermore, LM-031, but not licochalcone A, reduced activated AMPKα. Knockdown of CREB and NRF2 and treatment of AICAR (5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside), an AMPK activator, attenuated the aggregation-inhibiting and neurite outgrowth promoting effects of LM-031 on TBP/Q79 SH-SY5Y cells. The study results suggest the LM-031 as potential therapeutics for SCA17 and probable other polyQ diseases.

Highlights

Hereditary spinocerebellar ataxia types (SCAs) 1, 2, 3, 6, 7, and 17 are among a group of inherited neurodegenerative diseases caused by the expansion of unstable trinucleotide (CAG) repeats encoding expanded polyglutamine tracts [1]
The results demonstrated the low cytotoxicity of test compounds in TATAbox binding protein (TBP)/Q79-green fluorescent protein (GFP) 293 and SH-SY5Y cells, especially LM-031
As the neuroprotective effects of LM031 and licochalcone A in Aβ-GFP-expressing SH-SY5Y cells had been linked to CREB and nuclear factor erythroid 2-related factor 2 (NRF2) pathways [43], we examined the expressions of CREB, pCREB (S133), BCL2, GADD45B, and NRF2 by immunoblotting using specific antibodies

Summary

Introduction

Hereditary spinocerebellar ataxia types (SCAs) 1, 2, 3, 6, 7, and 17 are among a group of inherited neurodegenerative diseases caused by the expansion of unstable trinucleotide (CAG) repeats encoding expanded polyglutamine (polyQ) tracts [1]. CBP (cAMP-responsive element binding protein- (CREB-) binding protein), a cofactor for CREB-dependent transcriptional activation, has been shown to colocalize with the mutant polyQ containing protein in cell and mouse models and human HD brains [5]. Since transcriptional dysregulation has been shown to play a role in pathogenic mechanisms of SCA17 [17], we proposed that CREB-mediated gene expression is downregulated in SCA17 and compounds augmenting CREB activation can rescue the cytotoxicity. Since previously our SCA17 models displayed increased oxidative stress [29, 32, 42], we planned to investigate the role of AMPK in the pathogenesis of SCA17 and if aggregation-inhibitory compounds act on the AMPK pathway. We tested the effects of licochalcone A and these LM compounds targeting these pathways in TBP/Q79-GFP-expressing cell models

Materials and Methods

Results

Effects of LM-031 and Licochalcone A on polyQ

Discussion

Conflicts of Interest

Conclusions