LMK235, a small molecule inhibitor of HDAC4/5, protects dopaminergic neurons against neurotoxin- and α-synuclein-induced degeneration in cellular models of Parkinson's disease

Martina Mazzocchi,Susan R Goulding,Sean L Wyatt,Louise M Collins,Aideen M Sullivan,Gerard W O'Keeffe

doi:10.1016/j.mcn.2021.103642

Martina Mazzocchi, Susan R Goulding + Show 4 more

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https://doi.org/10.1016/j.mcn.2021.103642

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Abstract

Epigenetic modifications in neurodegenerative disease are under investigation for their roles in disease progression. Alterations in acetylation rates of certain Parkinson's disease (PD)-linked genes have been associated with the pathological progression of this disorder. In light of this, and given the lack of disease-modifying therapies for PD, HDAC inhibitors (HDIs) are under consideration as potential pharmacological agents. The neuroprotective effects of pan-HDACs and some class-specific inhibitors have been tested in in vivo and in vitro models of PD, with varying outcomes. Here we used gene co-expression analysis to identify HDACs that are associated with human dopaminergic (DA) neuron development. We identified HDAC3, HDAC5, HDAC6 and HDAC9 as being highly correlated with the DA markers, SLC6A3 and NR4A2. RT-qPCR revealed that mRNA expression of these HDACs exhibited similar temporal profiles during embryonic mouse midbrain DA (mDA) neuron development. We tested the neuroprotective potential of a number of class-specific small molecule HDIs on human SH-SY5Y cells, using neurite growth as a phenotypic readout of neurotrophic action. Neither the class I-specific HDIs, RGFP109 and RGFP966, nor the HDAC6 inhibitor ACY1215, had significant effects on neurite outgrowth. However, the class IIa HDI, LMK235 (a HDAC4/5 inhibitor), significantly increased histone acetylation and neurite outgrowth. We found that LMK235 increased BMP-Smad-dependent transcription in SH-SY5Y cells and that this was required for its neurite growth-promoting effects on SH-SY5Y cells and on DA neurons in primary cultures of embryonic day (E) 14 rat ventral mesencephalon (VM). These effects were also seen in SH-SY5Y cells transfected with HDAC5 siRNA. Furthermore, LMK235 treatment exerted neuroprotective effects against degeneration induced by the DA neurotoxin 1-methyl-4-phenylpyridinium (MPP+), in both SH-SY5Y cells and cultured DA neurons. Treatment with LMK235 was also neuroprotective against axonal degeneration induced by overexpression of wild-type (WT) or A53T mutant α-synuclein in both SH-SY5Y cells and primary cultures of DA neurons. In summary, these data show the neuroprotective potential of the class IIa HDI, LMK235, in cell models of relevance to PD.

Highlights

Parkinson's disease (PD) is a common, progressive neurodegenera tive disease (Poewe et al, 2017)
We discovered that Hdac3 (Fig. 1C), Hdac5 (Fig. 1D), Hdac6 (Fig. 1E) and Hdac9 (Fig. 1F) mRNA levels increased in the developing ventral mesencephalon (VM) from E10 to reach a peak at E12-E14
Given that distinct histone deacetylases (HDACs) are expressed in different cells and tissues, a lack of specificity in targeting HDAC subtypes may lead to side effects

Summary

Introduction

Parkinson's disease (PD) is a common, progressive neurodegenera tive disease (Poewe et al, 2017). The progression of PD pathology is associated with loss of dopaminergic (DA) neurons in the midbrain of the substantia nigra (SN), and their projections to the striatum, accompanied by accumulation of intracellular inclusions of misfolded α-synuclein in Lewy bodies (Spillantini et al, 1997). Another study found that induced pluripotent stem cells (iPSCs) generated from a PD patient carrying the A53T α-synuclein mutation developed evidence of neurite degeneration, such as swollen varicosities and spheroid inclusions (Kouroupi et al, 2017) In addition to these effects on α-synuclein and axons, other al terations of epigenetic mechanisms have been found in PD models and may contribute to the pathogenesis of this disease (Labbe et al, 2016)

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