Imbalanced autophagy causes synaptic deficits in a human model for neurodevelopmental disorders.
Katrin LindaElly I LewerissaAnouk H A VerbovenMichele GabrieleMonica FregaTeun M Klein GunnewiekLynn DevileeEdda UlfertsMarina HommersomAstrid OudakkerChantal SchoenmakerHans van BokhovenDirk SchubertGiuseppe TestaDavid A KoolenBert B A de VriesNael Nadif KasriPublished in: Autophagy (2021)
Macroautophagy (hereafter referred to as autophagy) is a finely tuned process of programmed degradation and recycling of proteins and cellular components, which is crucial in neuronal function and synaptic integrity. Mounting evidence implicates chromatin remodeling in fine-tuning autophagy pathways. However, this epigenetic regulation is poorly understood in neurons. Here, we investigate the role in autophagy of KANSL1, a member of the nonspecific lethal complex, which acetylates histone H4 on lysine 16 (H4K16ac) to facilitate transcriptional activation. Loss-of-function of KANSL1 is strongly associated with the neurodevelopmental disorder Koolen-de Vries Syndrome (KdVS). Starting from KANSL1-deficient human induced-pluripotent stem cells, both from KdVS patients and genome-edited lines, we identified SOD1 (superoxide dismutase 1), an antioxidant enzyme, to be significantly decreased, leading to a subsequent increase in oxidative stress and autophagosome accumulation. In KANSL1-deficient neurons, autophagosome accumulation at excitatory synapses resulted in reduced synaptic density, reduced GRIA/AMPA receptor-mediated transmission and impaired neuronal network activity. Furthermore, we found that increased oxidative stress-mediated autophagosome accumulation leads to increased MTOR activation and decreased lysosome function, further preventing the clearing of autophagosomes. Finally, by pharmacologically reducing oxidative stress, we could rescue the aberrant autophagosome formation as well as synaptic and neuronal network activity in KANSL1-deficient neurons. Our findings thus point toward an important relation between oxidative stress-induced autophagy and synapse function, and demonstrate the importance of H4K16ac-mediated changes in chromatin structure to balance reactive oxygen species- and MTOR-dependent autophagy.Abbreviations: APO: apocynin; ATG: autophagy related; BAF: bafilomycin A1; BSO: buthionine sulfoximine; CV: coefficient of variation; DIV: days in vitro; H4K16ac: histone 4 lysine 16 acetylation; iPSC: induced-pluripotent stem cell; KANSL1: KAT8 regulatory NSL complex subunit 1; KdVS: Koolen-de Vries Syndrome; LAMP1: lysosomal associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MEA: micro-electrode array; MTOR: mechanistic target of rapamycin kinase; NSL complex: nonspecific lethal complex; 8-oxo-dG: 8-hydroxydesoxyguanosine; RAP: rapamycin; ROS: reactive oxygen species; sEPSCs: spontaneous excitatory postsynaptic currents; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; SYN: synapsin; WRT: wortmannin.
Keyphrases
- oxidative stress
- cell death
- induced pluripotent stem cells
- endoplasmic reticulum stress
- dna damage
- reactive oxygen species
- diabetic rats
- stem cells
- induced apoptosis
- signaling pathway
- endothelial cells
- spinal cord
- ischemia reperfusion injury
- cell proliferation
- transcription factor
- gene expression
- ejection fraction
- hydrogen peroxide
- heat shock
- genome wide
- traumatic brain injury
- newly diagnosed
- high throughput
- prefrontal cortex
- chronic kidney disease
- high glucose
- air pollution
- protein kinase
- spinal cord injury
- mass spectrometry