Written by - Wang Yanan, Wang Yingfei

Editor-in-charge - Wang Sizhen

Editor — Binwei Yang

Many degenerative neurological disorders and intellectually stunted disorders are often accompanied by abnormal epigenetic modifications [1-3], such as Alzheimer's disease, which has a significantly reduced histone H4K16 acetylation modification [4

On August 26, 2022, Yingfei Wang's research group at the University of Texas Southwestern Medical Center published a research paper

In order to study the function of demethylase KDM6B in excitatory neurons in mouse brains, the Kdm6b gene (KDM6B-cKO) of mouse forebrain excitatory neurons was specifically knocked out and a series of behavioral studies related to motor, social, and cognitive abilities in mice were tested (Figure 1

Figure 1 KDM6B-cKO mice exhibit behavioral deficits associated with learning and memory

(Source: Wang, Yanan.

Through the quantitative analysis of KDMB-cKO mice hybridizing with green fluorescent protein (GFP)-tagged Thy1-GFP mice and their neuronal synapses, the researchers found that the number of neuronal dendritic spines in KDM6B-cKO mice was significantly reduced compared to normal mice (Figure 2 E-H

Figure 2 KDM6B-cKO mice exhibit decreased synaptic transmission activity and a decrease in the number of synaptic vesicles

(Source: Wang, Yanan.

In order to further study the specific molecular mechanisms of synaptic transmission abnormalities and learning cognitive impairment in KDM6B-cKO mice, the researchers performed systematic RNA sequencing, analyzed and compared the mRNA expression of KDM6B-KO and normal neurons (WT) (Figure 3 A-D), and found a series of important KDM6B downstream regulatory genes, including vesicle glutamate transporter VGLUT2 and another family member VGLUT1
.

VGLUT1/2 plays an important role
in the release of excitatory neurotransmitters.

These results suggest that KDM6B is likely to affect synaptic function
by modulating VGLUT1/2 expression.

Figure 3 RNA-seq analysis reveals that VGLUT1/2 is the downstream regulatory gene of interest for KDM6B

(Source: Wang, Yanan.
et al.
, Mol Psychiatry,2022）

So the researchers introduced protein expression
of foreign KDM6B or VGLUT1/2 by lentivirus infection with cultured KDM6B-KO neurons in vitro.

After quantitative analysis of neuronal dendritic spines and electrophysiological recording experiments, the researchers found that KDM6B-WT (6B-WT) with demethylase activity could restore the reduced number of dendrite spines in KDM6B-KO neurons and the frequency of excitatory postsynaptic current, while the mutant KDM6B-mut (6B-mut) lacking demethylase activity could not recover the number of dendrite spines and the frequency
of post-synaptic current.

At the same time, the researchers found that exogenous VGLUT1/2 expression also restores the reduced number of dendritic spines in KDM6B-KO neurons and the frequency of excitatory postsynaptic currents (Figure 4 A-E
).

These results suggest that VGLUT1/2 plays a crucial role
in KDM6B-regulated dendritic spine number and synaptic excitator neurotransmitter transport.

Fig.
4 KDM6B adjusts synaptic plasticity by VGLUT1/2

(Source: Wang, Yanan.
et al.
, Mol Psychiatry, 2022）

To further investigate the molecular mechanism by which KDM6B regulates VGLUT1/2, the researchers performed mass spectrometry screening and found that the microtubule-associated protein tau can interact with KDM6B (Figures 5 A, B
).

Reducing tau expression with shRNA can reduce the expression of VGLUT1/2 (Figure 5 C-E
).

In KDM6B-KO neurons, Tau-shRNA can reverse the increase in VGLUT1/2 caused by KDM6B overexpression (Figure 5 F-I
).

Further chromatin immunoprecipitation experiments (ChIP) showed that Tau-shRNA reduced the binding of KDM6B to the promoter site of the Slc17a6/7 gene, thereby increasing the H3K27me3 level at this site (Figure 5 J-M
).

The above results show that tau regulates the expression
of VGLUT1/2 by modulating H3K27me3 levels by recruiting KDM6B protein to the promoter site of Slc17a6/7 gene.

Figure 5 Tau protein plays a synergistic role in KDM6B regulating VGLUT1/2 expression

(Source: Wang, Yanan.
et al.
, Mol Psychiatry, 2022）

Fig.
6 Work summary Figure: KDM6B in collaboration with Tau regulates VGLUT/2 expression to affect synaptic plasticity

(Source: Wang, Yanan.
et al.
, Mol Psychiatry, 2022）

In summary, the study conducted a series of in vivo and in vitro experiments through gene-specific knockout, animal behavior, RNA-seq, protein profiling, chromatin immunoprecipitation, electron microscopy and electrophysiology, revealing the important physiological functions
of KDM6B and tau.

This project shows that the epigenetic regulator KDM6B was first recruited by the neuronally enriched protein tau to the VGLUT1/2 gene promoter region, thereby regulating the H3K27me3 level in this region and regulating the expression of the VGLUT1/2 protein, so it plays an important role in maintaining synaptic plasticity such as the number of dendritic spines in neurons, excitatory neurotransmitter transmission activity, and mouse learning memory and cognitive function (Figure 6
).

This work provides a new perspective for understanding the function of demethylase KDM6B and a new basis
for understanding epigenetics to regulate synaptic plasticity.

Of course, there are still many important questions to be solved in this work, such as the role of protein tau phosphorylation in this regulatory process, and the role of KDM6B in degenerative neurological diseases such as Alzheimer's or autism
.

Original link: https://doi.
org/10.
1038/s41380-022-01750-0

Corresponding Author: Wang Yingfei (fifth from right); First Author: Wang Yanan (first from the right)

(Photo courtesy of: Wang Yingfei Research Group, University of Texas Southwestern Medical Center)

Selected articles from previous issues

[1] Cereb Cortex—Excavation and analysis of imaging subtypes for the heterogeneity of schizophrenia

[2] Front Cell Neurosci Review:Gamma Neural Oscillation and Central Nervous System Diseases: Mechanisms and Therapeutic Advances

[3] The NAR-He Cheng/Su Zhida team found that topoisomerase IIA can regulate adult neurogenesis in the subependymal region

[4] The Sci Adv-Liao Wenbo team has made important progress in the adaptive evolution of amphibian brain volume

[5] J Neuroinflammation—From Changchun/Jian Zhang's team found that targeting proteoglycan receptors after hemorrhagic stroke protects white matter integrity and promotes the recovery of neurological function

[6] Front Aging Neurosci—Zeng Yanbing's team established a predictive model and revealed the effects of behavioral changes on cognitive impairment in the elderly

[7] Sci Adv-Zhao Cunyou/Chen Rongqing team revealed the mechanism of microRNA inducing social and memory abnormalities in mice: miR-501-3p expression defects enhance glutamate delivery

[8] Sci Adv-Zhang Yi's research group found important neurons that regulate drug addiction behavior

[9] J Infect-Yifei Wang's team revealed that the maMDC2 high-expression gene in Alzheimer's disease microglia positively regulates the innate antiviral response of neurophilic virus infection

[10] Sci Adv—Xia Kun/Shen Yiping/Guo Hui revealed the relationship between key regulatory genes of stress particles and neurodevelopmental disorders

Recommended for high-quality scientific research training courses

【1】Special Training on Biomedical Statistics for Clinical Prediction of R Language (October 15-16, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing)

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End of this article