Arid1a regulates neural stem/progenitor cell proliferation and differentiation during cortical development

Nicotinamide Riboside Promotes the Proliferation of Endogenous Neural Stem Cells to Repair Spinal Cord Injury

Activation of endogenous neural stem cells (NSC) is one of the most potential measures for neural repair after spinal cord injury. However, methods for regulating neural stem cell behavior are still limited. Here, we investigated the effects of nicotinamide riboside promoting the proliferation of endogenous neural stem cells to repair spinal cord injury. Nicotinamide riboside promotes the proliferation of endogenous neural stem cells and regulates their differentiation into neurons. In addition, nicotinamide riboside significantly restored lower limb motor dysfunction caused by spinal cord injury. Nicotinamide riboside plays its role in promoting the proliferation of neural stem cells by activating the Wnt signaling pathway through the LGR5 gene. Knockdown of the LGR5 gene by lentivirus eliminates the effect of nicotinamide riboside on the proliferation of endogenous neural stem cells. In addition, administration of Wnt pathway inhibitors also eliminated the proliferative effect of nicotinamide riboside. Collectively, these findings demonstrate that nicotinamide promotes the proliferation of neural stem cells by targeting the LGR5 gene to activate the Wnt pathway, which provides a new way to repair spinal cord injury.

Chromatin remodeling in tissue stem cell fate determination

Tissue stem cells (TSCs), which reside in specialized tissues, constitute the major cell sources for tissue homeostasis and regeneration, and the contribution of transcriptional or epigenetic regulation of distinct biological processes in TSCs has been discussed in the past few decades. Meanwhile, ATP-dependent chromatin remodelers use the energy from ATP hydrolysis to remodel nucleosomes, thereby affecting chromatin dynamics and the regulation of gene expression programs in each cell type. However, the role of chromatin remodelers in tissue stem cell fate determination is less well understood. In this review, we systematically discuss recent advances in epigenetic control by chromatin remodelers of hematopoietic stem cells, intestinal epithelial stem cells, neural stem cells, and skin stem cells in their fate determination and highlight the importance of their essential role in tissue homeostasis, development, and regeneration. Moreover, the exploration of the molecular and cellular mechanisms of TSCs is crucial for advancing our understanding of tissue maintenance and for the discovery of novel therapeutic targets.

Proteomic insights into the regulatory function of ARID1A in colon cancer cells

The AT-rich interacting domain-containing protein 1A (ARID1A) is a tumor suppressor gene that has been implicated in several cancers, including colorectal cancer (CRC). The present study used a proteomic approach to elucidate the molecular mechanisms of ARID1A in CRC carcinogenesis. Stable ARID1A-overexpressing SW48 colon cancer cells were established using lentivirus transduction and the successful overexpression of ARID1A was confirmed by western blotting. Label-free quantitative proteomic analysis using liquid chromatography-tandem mass spectrometry identified 705 differentially altered proteins in the ARID1A-overexpressing cells, with 310 proteins significantly increased and 395 significantly decreased compared with empty vector control cells. Gene Ontology enrichment analysis highlighted the involvement of the altered proteins mainly in the Wnt signaling pathway. Western blotting supported these findings, as a decreased protein expression of Wnt target genes, including c-Myc, transcription factor T cell factor-1/7 and cyclin D1, were observed in ARID1A-overexpressing cells. Among the altered proteins involved in the Wnt signaling pathway, the interaction network analysis revealed that ARID1A exhibited a direct interaction with E3 ubiquitin-protein ligase zinc and ring finger 3 (ZNRF3), a negative regulator of the Wnt signaling pathway. Further analyses using the The Cancer Genome Atlas colon adenocarcinoma public dataset revealed that ZNRF3 expression significantly impacted the overall survival of patients with CRC and was positively correlated with ARID1A expression. Finally, an increased level of ZNRF3 in ARID1A-overexpressing cells was confirmed by western blotting. In conclusion, the findings of the present study suggest that ARID1A negatively regulates the Wnt signaling pathway through ZNRF3, which may contribute to CRC carcinogenesis.

Rare predicted deleterious FEZF2 variants are associated with a neurodevelopmental phenotype

FEZF2 encodes a transcription factor critical to neurodevelopment that regulates other neurodevelopment genes. Rare variants in FEZF2 have previously been suggested to play a role in autism, and cases of 3p14 microdeletions that include FEZF2 share a neurodevelopmental phenotype including mild dysmorphic features and intellectual disability. We identified seven heterozygous predicted deleterious variants in FEZF2 (three frameshifts, one recurrent missense in two independent cases, one nonsense, and one complete gene deletion) in unrelated individuals with neurodevelopmental disorders including developmental delay/intellectual disability, autism, and/or attention-deficit/hyperactivity. Variants were confirmed to be de novo in five of seven cases and paternally inherited from an affected father in one. Predicted deleterious variants in FEZF2 may affect the expression of genes that are involved in fate choice pathways in developing neurons, and thus contribute to the neurodevelopmental phenotype. Future studies are needed to clarify the mechanism by which FEZF2 leads to this neurodevelopmental disorder.

The effects of ARID1A mutation in gastric cancer and its significance for treatment

Gastric cancer (GC) has emerged as a significant issue in public health all worldwide as a result of its high mortality rate and dismal prognosis. AT-rich interactive domain 1 A (ARID1A) is a vital component of the switch/sucrose-non-fermentable (SWI/SNF) chromatin remodeling complex, and ARID1A mutations occur in various tumors, leading to protein loss and decreased expression; it then affects the tumor biological behavior or prognosis. More significantly, ARID1A mutations will likely be biological markers for immune checkpoint blockade (ICB) treatment and selective targeted therapy. To provide theoretical support for future research on the stratification of individuals with gastric cancer with ARID1A as a biomarker to achieve precision therapy, we have focused on the clinical significance, predictive value, underlying mechanisms, and possible treatment strategies for ARID1A mutations in gastric cancer in this review.

Abnormal chromatin remodeling caused by ARID1A deletion leads to malformation of the dentate gyrus

ARID1A, an SWI/SNF chromatin-remodeling gene, is commonly mutated in cancer and hypothesized to be a tumor suppressor. Recently, loss-of-function of ARID1A gene has been shown to cause intellectual disability. Here we generate Arid1a conditional knockout mice and investigate Arid1a function in the hippocampus. Disruption of Arid1a in mouse forebrain significantly decreases neural stem/progenitor cells (NSPCs) proliferation and differentiation to neurons within the dentate gyrus (DG), increasing perinatal and postnatal apoptosis, leading to reduced hippocampus size. Moreover, we perform single-cell RNA sequencing (scRNA-seq) to investigate cellular heterogeneity and reveal that Arid1a is necessary for the maintenance of the DG progenitor pool and survival of post-mitotic neurons. Transcriptome and ChIP-seq analysis data demonstrate that ARID1A specifically regulates Prox1 by altering the levels of histone modifications. Overexpression of downstream target Prox1 can rescue proliferation and differentiation defects of NSPCs caused by Arid1a deletion. Overall, our results demonstrate a critical role for Arid1a in the development of the hippocampus and may also provide insight into the genetic basis of intellectual disabilities such as Coffin-Siris syndrome, which is caused by germ-line mutations or microduplication of Arid1a.

Differential Contributions of mSWI/SNF Chromatin Remodeler Sub-Families to Myoblast Differentiation

Mammalian SWI/SNF (mSWI/SNF) complexes are ATP-dependent chromatin remodeling enzymes that are critical for normal cellular functions. mSWI/SNF enzymes are classified into three sub-families based on the presence of specific subunit proteins. The sub-families are Brm- or Brg1-associated factor (BAF), ncBAF (non-canonical BAF), and polybromo-associated BAF (PBAF). The biological roles for the different enzyme sub-families are poorly described. We knocked down the expression of genes encoding unique subunit proteins for each sub-family, Baf250A, Brd9, and Baf180, which mark the BAF, ncBAF, and PBAF sub-families, respectively, and examined the requirement for each in myoblast differentiation. We found that Baf250A and the BAF complex were required to drive lineage-specific gene expression. KD of Brd9 delayed differentiation. However, while the Baf250A-dependent gene expression profile included myogenic genes, the Brd9-dependent gene expression profile did not, suggesting Brd9 and the ncBAF complex indirectly contributed to differentiation. Baf180 was dispensable for myoblast differentiation. The results distinguish between the roles of the mSWI/SNF enzyme sub-families during myoblast differentiation.

ARID1A Inactivation Increases Expression of circ0008399 and Promotes Cisplatin Resistance in Bladder Cancer

OBJECTIVE

Cisplatin (CDDP)-based chemotherapy is a first-line, drug regimen for muscle-invasive bladder cancer (BC) and metastatic bladder cancer. Clinically, resistance to CDDP restricts the clinical benefit of some bladder cancer patients. AT-rich interaction domain 1A (ARID1A) gene mutation occurs frequently in bladder cancer; however, the role of CDDP sensitivity in BC has not been studied.

METHODS

We established ARID1A knockout BC cell lines using CRISPR/Cas9 technology. IC50 determination, flow cytometry analysis of apoptosis, and tumor xenograft assays were performed to verify changes in the CDDP sensitivity of BC cells losing ARID1A. qRT-PCR, Western blotting, RNA interference, bioinformatic analysis, and ChIP-qPCR analysis were performed to further explore the potential mechanism of ARID1A inactivation in CDDP sensitivity in BC.

RESULTS

It was found that ARID1A inactivation was associated with CDDP resistance in BC cells. Mechanically, loss of ARID1A promoted the expression of eukaryotic translation initiation factor 4A3 (EIF4A3) through epigenetic regulation. Increased expression of EIF4A3 promoted the expression of hsa_circ_0008399 (circ0008399), a novel circular RNA (circRNA) identified in our previous study, which, to some extent, showed that ARID1A deletion caused CDDP resistance through the inhibitory effect of circ0008399 on the apoptosis of BC cells. Importantly, EIF4A3-IN-2 specifically inhibited the activity of EIF4A3 to reduce circ0008399 production and restored the sensitivity of ARID1A inactivated BC cells to CDDP.

CONCLUSION

Our research deepens the understanding of the mechanisms of CDDP resistance in BC and elucidates a potential strategy to improve the efficacy of CDDP in BC patients with ARID1A deletion through combination therapy targeting EIF4A3.

Role of brahma-related gene 1/brahma-associated factor subunits in neural stem/progenitor cells and related neural developmental disorders

Different fates of neural stem/progenitor cells (NSPCs) and their progeny are determined by the gene regulatory network, where a chromatin-remodeling complex affects synergy with other regulators. Here, we review recent research progress indicating that the BRG1/BRM-associated factor (BAF) complex plays an important role in NSPCs during neural development and neural developmental disorders. Several studies based on animal models have shown that mutations in the BAF complex may cause abnormal neural differentiation, which can also lead to various diseases in humans. We discussed BAF complex subunits and their main characteristics in NSPCs. With advances in studies of human pluripotent stem cells and the feasibility of driving their differentiation into NSPCs, we can now investigate the role of the BAF complex in regulating the balance between self-renewal and differentiation of NSPCs. Considering recent progress in these research areas, we suggest that three approaches should be used in investigations in the near future. Sequencing of whole human exome and genome-wide association studies suggest that mutations in the subunits of the BAF complex are related to neurodevelopmental disorders. More insight into the mechanism of BAF complex regulation in NSPCs during neural cell fate decisions and neurodevelopment may help in exploiting new methods for clinical applications.

The landscape of m1A modification and its posttranscriptional regulatory functions in primary neurons

Cerebral ischaemia‒reperfusion injury (IRI), during which neurons undergo oxygen-glucose deprivation/reoxygenation (OGD/R), is a notable pathological process in many neurological diseases. N1-methyladenosine (m¹A) is an RNA modification that can affect gene expression and RNA stability. The m¹A landscape and potential functions of m¹A modification in neurons remain poorly understood. We explored RNA (mRNA, lncRNA, and circRNA) m¹A modification in normal and OGD/R-treated mouse neurons and the effect of m¹A on diverse RNAs. We investigated the m¹A landscape in primary neurons, identified m¹A-modified RNAs, and found that OGD/R increased the number of m¹A RNAs. m¹A modification might also affect the regulatory mechanisms of noncoding RNAs, e.g., lncRNA-RNA binding proteins (RBPs) interactions and circRNA translation. We showed that m¹A modification mediates the circRNA/lncRNA‒miRNA-mRNA competing endogenous RNA (ceRNA) mechanism and that 3' untranslated region (3'UTR) modification of mRNAs can hinder miRNA-mRNA binding. Three modification patterns were identified, and genes with different patterns had intrinsic mechanisms with potential m¹A-regulatory specificity. Systematic analysis of the m¹A landscape in normal and OGD/R neurons lays a critical foundation for understanding RNA modification and provides new perspectives and a theoretical basis for treating and developing drugs for OGD/R pathology-related diseases.

Supt16 haploinsufficiency causes neurodevelopment disorder by disrupting MAPK pathway in neural stem cells

Chromatin regulators constitute a fundamental means of transcription regulation, which have been implicated in neurodevelopment and neurodevelopment disorders (NDDs). Supt16, one of candidate genes for NDDs, encodes the large subunit of facilitates chromatin transcription. However, the underlying mechanisms remain poorly understood. Here, Supt16+/- mice was generated, modeling the neurodevelopment disorder. Abnormal cognitive and social behavior was observed in the Supt16  +/- mice. Simultaneously, the number of neurocytes in the cerebral cortex and hippocampus is decreased, which might be resulted from the impairment of mouse neural stem cells (mNSCs) in the SVZ. Supt16 haploinsufficiency affects the proliferation and apoptosis of mNSCs. As the RNA-seq and chromatic immunoprecipitation sequencing assays showed, Supt16 haploinsufficiency disrupts the stemness of mNSCs by inhibiting MAPK signal pathway. Thus, this study demonstrates a critical role of Supt16 gene in the proliferation and apoptosis of mNSCs and provides a novel insight in the pathogenesis of NDDs.

Supt16 Haploinsufficiency Impairs PI3K/AKT/mTOR/Autophagy Pathway in Human Pluripotent Stem Cells Derived Neural Stem Cells

The maintenance of neural stem cells (NSCs) plays a critical role in neurodevelopment and has been implicated in neurodevelopmental disorders (NDDs). However, the underlying mechanisms linking defective human neural stem cell self-renewal to NDDs remain undetermined. Our previous study found that Supt16 haploinsufficiency causes cognitive and social behavior deficits by disrupting the stemness maintenance of NSCs in mice. However, its effects and underlying mechanisms have not been elucidated in human neural stem cells (hNSCs). Here, we generated Supt16^+/- induced pluripotent stem cells (iPSCs) and induced them into hNSCs. The results revealed that Supt16 heterozygous hNSCs exhibit impaired proliferation, cell cycle arrest, and increased apoptosis. As the RNA-seq analysis showed, Supt16 haploinsufficiency inhibited the PI3K/AKT/mTOR pathway, leading to rising autophagy, and further resulted in the dysregulated expression of multiple proteins related to cell proliferation and apoptotic process. Furthermore, the suppression of Supt16 heterozygous hNSC self-renewal caused by autophagy activation could be rescued by MHY1485 treatment or reproduced in rapamycin-treated hNSCs. Thus, our results showed that Supt16 was essential for hNSC self-renewal and its haploinsufficiency led to cell cycle arrest, impaired cell proliferation, and increased apoptosis of hNSCs by regulating the PI3K/AKT/mTOR/autophagy pathway. These provided a new insight to understand the causality between the Supt16 heterozygous NSCs and NDDs in humans.

Acetate supplementation restores cognitive deficits caused by ARID1A haploinsufficiency in excitatory neurons

Mutations in AT-rich interactive domain-containing protein 1A (ARID1A) cause Coffin-Siris syndrome (CSS), a rare genetic disorder that results in mild to severe intellectual disabilities. However, the biological role of ARID1A in the brain remains unclear. In this study, we report that the haploinsufficiency of ARID1A in excitatory neurons causes cognitive impairment and defects in hippocampal synaptic transmission and dendritic morphology in mice. Similarly, human embryonic stem cell-derived excitatory neurons with deleted ARID1A exhibit fewer dendritic branches and spines, and abnormal electrophysiological activity. Importantly, supplementation of acetate, an epigenetic metabolite, can ameliorate the morphological and electrophysiological deficits observed in mice with Arid1a haploinsufficiency, as well as in ARID1A-null human excitatory neurons. Mechanistically, transcriptomic and ChIP-seq analyses demonstrate that acetate supplementation can increase the levels of H3K27 acetylation at the promoters of key regulatory genes associated with neural development and synaptic transmission. Collectively, these findings support the essential roles of ARID1A in the excitatory neurons and cognition and suggest that acetate supplementation could be a potential therapeutic intervention for CSS.

Transcription Pause and Escape in Neurodevelopmental Disorders

Transcription pause-release is an important, highly regulated step in the control of gene expression. Modulated by various factors, it enables signal integration and fine-tuning of transcriptional responses. Mutations in regulators of pause-release have been identified in a range of neurodevelopmental disorders that have several common features affecting multiple organ systems. This review summarizes current knowledge on this novel subclass of disorders, including an overview of clinical features, mechanistic details, and insight into the relevant neurodevelopmental processes.

Impact of SARS-CoV-2 on Host Factors Involved in Mental Disorders

COVID-19, caused by SARS-CoV-2, is a systemic illness due to its multiorgan effects in patients. The disease has a detrimental impact on respiratory and cardiovascular systems. One early symptom of infection is anosmia or lack of smell; this implicates the involvement of the olfactory bulb in COVID-19 disease and provides a route into the central nervous system. However, little is known about how SARS-CoV-2 affects neurological or psychological symptoms. SARS-CoV-2 exploits host receptors that converge on pathways that impact psychological symptoms. This systemic review discusses the ways involved by coronavirus infection and their impact on mental health disorders. We begin by briefly introducing the history of coronaviruses, followed by an overview of the essential proteins to viral entry. Then, we discuss the downstream effects of viral entry on host proteins. Finally, we review the literature on host factors that are known to play critical roles in neuropsychiatric symptoms and mental diseases and discuss how COVID-19 could impact mental health globally. Our review details the host factors and pathways involved in the cellular mechanisms, such as systemic inflammation, that play a significant role in the development of neuropsychological symptoms stemming from COVID-19 infection.

Arid1a regulates neural stem/progenitor cell proliferation and differentiation during cortical development

Objective

Neurodevelopmental diseases are common disorders caused by the disruption of essential neurodevelopmental processes. Recent human exome sequencing and genome‐wide association studies have shown that mutations in the subunits of the SWI/SNF (BAF) complex are risk factors for neurodevelopmental diseases. Clinical studies have found that ARID1A (BAF250a) is the most frequently mutated SWI/SNF gene and its mutations lead to mental retardation and microcephaly. However, the function of ARID1A in brain development and its underlying mechanisms still remain elusive.

Methods

The present study used Cre/loxP system to generate an Arid1a conditional knockout mouse line. Cell proliferation, cell apoptosis and cell differentiation of NSPCs were studied by immunofluorescence staining. In addition, RNA‐seq and RT‐PCR were performed to dissect the molecular mechanisms of Arid1a underlying cortical neurogenesis. Finally, rescue experiments were conducted to evaluate the effects of Neurod1 or Fezf2 overexpression on the differentiation of NSPCs in vitro.

Results

Conditional knockout of Arid1a reduces cortical thickness in the developing cortex. Arid1a loss of function inhibits the proliferation of radial glial cells, and increases cell death during late cortical development, and leads to dysregulated expression of genes associated with proliferation and differentiation. Overexpression of Neurod1 or Fezf2 in Arid1a cKO NSPCs rescues their neural differentiation defect in vitro.

Conclusions

This study demonstrates for the first time that Arid1a plays an important role in regulating the proliferation and differentiation of NSPCs during cortical development, and proposes several gene candidates that are worth to understand the pathological mechanisms and to develop novel interventions of neurodevelopment disorders caused by Arid1a mutations.