Knock-Down of HDAC2 in Human Induced Pluripotent Stem Cell Derived Neurons Improves Neuronal Mitochondrial Dynamics, Neuronal Maturation and Reduces Amyloid Beta Peptides.

Joshua Davis,Jessica E Young,Chizuru Kinoshita,Richard S Morrison,Fred Yeboah,Bonnie J Berry,Kira Evitts,Michelle Lee,Harald Frankowski,Yoshito Kinoshita

doi:10.3390/ijms22052526

Abstract

Histone deacetylase 2 (HDAC2) is a major HDAC protein in the adult brain and has been shown to regulate many neuronal genes. The aberrant expression of HDAC2 and subsequent dysregulation of neuronal gene expression is implicated in neurodegeneration and brain aging. Human induced pluripotent stem cell-derived neurons (hiPSC-Ns) are widely used models for studying neurodegenerative disease mechanisms, but the role of HDAC2 in hiPSC-N differentiation and maturation has not been explored. In this study, we show that levels of HDAC2 progressively decrease as hiPSCs are differentiated towards neurons. This suppression of HDAC2 inversely corresponds to an increase in neuron-specific isoforms of Endophilin-B1, a multifunctional protein involved in mitochondrial dynamics. Expression of neuron-specific isoforms of Endophilin-B1 is accompanied by concomitant expression of a neuron-specific alternative splicing factor, SRRM4. Manipulation of HDAC2 and Endophilin-B1 using lentiviral approaches shows that the knock-down of HDAC2 or the overexpression of a neuron-specific Endophilin-B1 isoform promotes mitochondrial elongation and protects against cytotoxic stress in hiPSC-Ns, while HDAC2 knock-down specifically influences genes regulating mitochondrial dynamics and synaptogenesis. Furthermore, HDAC2 knock-down promotes enhanced mitochondrial respiration and reduces levels of neurotoxic amyloid beta peptides. Collectively, our study demonstrates a role for HDAC2 in hiPSC-neuronal differentiation, highlights neuron-specific isoforms of Endophilin-B1 as a marker of differentiating hiPSC-Ns and demonstrates that HDAC2 regulates key neuronal and mitochondrial pathways in hiPSC-Ns.

Highlights

Given that epigenetic dysregulation [14,15], mitochondrial dysfunction [16,17,18], and synaptic dysfunction [19] are all implicated in multiple neurodevelopmental and neurodegenerative diseases, we investigated whether modulation of histone deacetylase 2 (HDAC2) expression would impact neuronal maturation, mitochondrial dynamics and synaptic gene expression in neuronal cells derived from Human induced pluripotent stem cells (hiPSC)
We examined the expression of HDAC2 and Endo-B1 isoforms in differentiating neuronal cells compared with hiPSCs and neural progenitor cells (NPCs)
We demonstrated that HDAC2 regulates expressiondiseases of neuron-specific

Summary

Introduction

Epigenetic dysregulation is a feature of many neurologic disorders, leading to aberrant gene expression that affects cellular metabolism and function [1]. Histone acetylation and deacetylation is a common epigenetic modification that can regulate gene expression by controlling chromatin structure. Imbalance of histone acetylation and deacetylation contributes to neuronal dysfunction in neurodegenerative disease [10,11]. Histone deacetylase 2 (HDAC2) is an abundant HDAC in the brain and has been shown to regulate genes involved in cognition, learning, and memory [4,5]. Dysregulation of HDAC2 has been implicated in neurodegenerative disorders including Alzheimer’s Disease (AD) [3,10,12], where it may contribute to cognitive impairment [5]. We demonstrated that HDAC2 is involved in regulation of neuronal mitochondrial dynamics via the expression of Endophilin-B1 (SH3GLB1)

Methods

Results

Conclusion