Biological sex shapes the manifestation and progression of neurodevelopmental disorders (NDDs), however, the underlying mechanisms remains unclear. Hemideletion of the 16p11.2 region (16p11.2 del/+) is associated with NDDs, and 16p11.2 del/+ mice exhibit sex-specific, striatum-related phenotypes relevant to NDDs. In this study, using snRNA-seq, we identify cell type- and sex-specific transcriptomic changes in D1- and D2-spiny projection neurons (SPNs), with greater impact in males. Fiber photometry recordings reveal reduced neuronal activity in the dorsal striatum of 16p11.2 del/+ males, but not females, with D2-SPNs identified as the primary contributors to this reduction. Behaviorally, we utilize conditional genetic approaches and find that selective hemideletion in D2-SPNs, but not D1-SPNs, induces male-specific hyperactivity, whereas cortical hemideletion increases hyperactivity in both sexes. Thus, a locus linked to NDDs acts in distinct striatal circuits, selectively impacting behavior in a sex- and cell type-specific manner. This study demonstrates that 16p11.2 hemideletion, a genetic deletion linked to neurodevelopmental disorders, affects male and female mice differently, altering specific striatal neuronal circuits and driving sex-specific behavioral changes.

Chromatin regulators have a prestigious function in controlling the proper development and maintenance of homeostasis. Aberrant chromatin remodeling and epigenetic modification lead to dysregulated gene expression, which eventually causes diverse human diseases. The chromodomain (CD)-containing family proteins are among the most important chromatin modulators—especially chromatin readers that preferentially recognize and regulate methylated histones. The human genome encodes 41 CDs in 32 different proteins, which can be further grouped into three major subfamilies. Here, we review current insights regarding this large CD-containing protein family in regulating cellular proliferation and development, chromatin dynamics and maintenance, DNA damage response and repair, transcription regulation, and immune homeostasis. We highlight the uncovered physiological roles of CD-containing proteins in distinct human maladies ranging from developmental disorders to cancers as well as recent progress in developing and testing inhibitors targeting CD-containing proteins for treating human diseases.

Abstract Fundamentally, cancer is a disease caused by genetic and epigenetic alterations that converge to reprogram gene expression networks, leading to unrestrained proliferation. Glioblastoma (GBM) is the most prevalent and aggressive primary brain cancer, median survival being approximately one year and the 5-year survival rate being only 5%. Despite decades of effort, this devastating picture has not appreciably improved and effective therapies have been elusive for GBM patients. A better understanding of GBM biology is essential for developing more effective therapies. Although several genetic alterations have been implicated in gliomagenesis, driving genetic factors responsible for GBM are still obscure, and the interplay between genetic alterations and epigenetic dysregulation is largely undocumented during the gliomagenic process. Here, we show that CHD5 — a gene mapping to the 1p36 chromosomal region that is notoriously deleted in many cancers, is recurrently deleted in over 20% of GBM cases and is further downregulated through epigenetic means. To delineate how CHD5 loss promotes gliomagenesis, we established a glioma-prone mouse model harboring conditional alleles of Pten, Trp53, and Chd5. We developed an engineered mouse neural stem cell (NSCs)-based strategy to elicit glioma formation, as NSCs are the major cell-of-origin for GBM. We show that Chd5 loss significantly impairs NSCs differentiation while promoting proliferation, transformation, and gliomagenesis in vivo. Mechanistically, Chd5 forms a Chd3-containing but Chd4-independent NuRD complex that directly binds the Myc promoter and super enhancers to govern Myc expression in normal NSCs, with the Snf2 domain of Chd5 playing the most critical chromatin regulating role in the context of GBM. Chd5 loss triggers the remodeling of chromatin, enhances accessibility, and augments Myc expression, leading to the formation of highly aggressive glioma. Furthermore, reactivating CHD5 in human GBM xenograft models significantly extends survival. This work demonstrates the tumor suppressive role of CHD5 in gliomagenesis, providing therapeutic insights for cancers with 1p36 deletions. In parallel, this work presents a powerful strategy for rapidly interrogating gene function during gliomagenesis using engineering NSCs and highlights the generation of novel mouse models with classic clinical features of GBM, offering new approaches for elucidating GBM biology that can inform on therapeutic opportunities for treating patients with GBM. Citation Format: Xueqin Sherine Sun, Alea Mills. CHD5 suppresses glioblastoma by inhibiting MYC [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr B014.

Abstract Fundamentally, cancer arises from genetic and epigenetic alterations that interplay to reprogram gene expression networks, leading to unrestrained proliferation. Glioblastoma (GBM) is the most prevalent and aggressive primary brain cancer, with a median survival of approximately one year and a 5-year survival rate of just 5%. The standard care for GBM patients has remained unchanged for decades, underscoring the need for a better understanding of GBM biology to develop more effective therapies. The relatively low genetic mutation burden in GBM highlights the significant role of epigenetic mechanisms in its pathogenesis. Our recent work shows that chromatin remodeling plays pivotal roles in GBM pathogenesis. The BRD8-driven EP400 chromatin remodeling complex maintains GBM by crippling p53-mediated tumor suppression in an unprecedented way through hijacking the histone variant H2AZ at p53 target loci, enforcing a repressive chromatin state that prevents p53-mediated transactivation. Targeting BRD8 in TP53WT GBM, which makes up ~71% of all GBM cases, enhances chromatin accessibility by evicting H2AZ. This restores p53-mediated transactivation of its targets, reestablishes cell cycle arrest, inhibits gliomagenesis, and prolongs survival in xenograft models of TP53WT GBM. Conversely, the NuRD chromatin remodeling complex driven by CHD5 governs the MYC-mediated oncogenic network to prevent gliomagenesis. Mechanistically, CHD5 forms a CHD3-containing but CHD4-independent NuRD complex that directly binds to the MYC promoter and super enhancers. Chd5 loss triggers the remodeling of chromatin, enhances chromatin accessibility at Myc loci, augments Myc expression, significantly impairs NSCs differentiation while promotes proliferation, transformation, and gliomagenesis in vivo. Furthermore, reactivating CHD5 in human GBM xenograft models significantly extends survival. Thus, our findings reveal previously unappreciated epigenetic mechanisms by which GBM cells reprogram both tumor-suppressive and oncogenic transcription networks to facilitate their outgrowth. This sheds new light on our understanding of GBM malignancy and provides promising therapeutic opportunities for treating patients with this devastating malignancy.

Protein arginine methyltransferase 5 (PRMT5) is a critical oncogenic factor in various cancers, and its inhibition has shown promise in suppressing tumor growth. However, the role of PRMT5 in squamous cell carcinoma (SCC) remains largely unexplored. In this study, we analyzed SCC patient data from The Cancer Genome Atlas (TCGA) and the Cancer Dependency Map (DepMap) to investigate the relationship between PRMT5 and SCC proliferation. We employed competition-based cell proliferation assays, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays, flow cytometry, and in vivo mouse modeling to examine the regulatory roles of PRMT5 and its binding partner WDR77 (WD repeat domain 77). We identified downstream targets, including the p63 isoform ΔNp63α and the cyclin-dependent kinase inhibitor p21, through single-cell RNA-seq, RT-qPCR, and Western blot analyses. Our findings demonstrate that upregulation of PRMT5 and WDR77 correlates with the poor survival of head and neck squamous cell carcinoma (HNSCC) patients. PRMT5/WDR77 regulates the HNSCC-specific transcriptome and facilitates SCC proliferation by promoting cell cycle progression. The PRMT5 and WDR77 stabilize the ΔNp63α Protein, which in turn, inhibits p21. Moreover, depletion of PRMT5 and WDR77 repress SCC in vivo. This study reveals for the first time that PRMT5 and WDR77 synergize to promote SCC proliferation via the ΔNp63α-p21 axis, highlighting a novel therapeutic target for SCC.

Abstract Fundamentally, cancer is a disease caused by genetic and epigenetic alterations that converge to reprogram gene expression networks, leading to unrestrained proliferation. Glioblastoma (GBM) is the most prevalent and aggressive primary brain cancer, median survival being approximately one year and the 5-year survival rate being only 5%. Despite decades of effort, this devastating picture has not appreciably improved and effective therapies have been elusive for GBM patients. A better understanding of GBM biology is essential for developing more effective therapies. Although several genetic alterations have been implicated in gliomagenesis, driving genetic factors responsible for GBM are still obscure, and the interplay between genetic alterations and epigenetic dysregulation is largely undocumented during the gliomagenic process. Here, we show that CHD5 — a gene mapping to the 1p36 chromosomal region that is notoriously deleted in many cancers, is recurrently deleted in over 20% of GBM cases and is further downregulated through epigenetic means. To delineate how CHD5 loss promotes gliomagenesis, we established a glioma-prone mouse model harboring conditional alleles of Pten, Trp53, and Chd5. We developed an engineered mouse neural stem cell (NSCs)-based strategy to elicit glioma formation, as NSCs are the major cell-of-origin for GBM. We show that Chd5 loss significantly impairs NSCs differentiation while promoting proliferation, transformation, and gliomagenesis in vivo. Mechanistically, Chd5 forms a Chd3-containing but Chd4-independent NuRD complex that directly binds the Myc promoter and super enhancers to govern Myc expression in normal NSCs, with the Snf2 domain of Chd5 playing the most critical chromatin regulating role in the context of GBM. Chd5 loss triggers the remodeling of chromatin, enhances accessibility, and augments Myc expression, leading to the formation of highly aggressive glioma. Furthermore, reactivating CHD5 in human GBM xenograft models significantly extends survival. This work demonstrates the tumor suppressive role of CHD5 in gliomagenesis, providing therapeutic insights for cancers with 1p36 deletions. In parallel, this work presents a powerful strategy for rapidly interrogating gene function during gliomagenesis using engineering NSCs, and the generation of novel mouse models with classic clinical features of GBM, offering new approaches for elucidating GBM biology that can inform on therapeutic opportunities for treating patients with GBM. Citation Format: Xueqin Sherine Sun, Alea Mills. CHD5 suppresses glioblastoma by inhibiting MYC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1257.

Abstract Glioblastoma (GBM) is the most common and deadly adult primary brain malignancy. Median survival is just 12-14 months, with only about 5% of GBM patients surviving 5 years after diagnosis. This picture has not substantially improved over decades and there is an urgent need to discover more specific and effective treatments for this deadly malignancy. We discovered the bromodomain-containing chromatin regulator BRD8 as essential to GBM lacking p53 mutations (TP53WT), which make up ~71% of cases (1). BRD8 maintains malignancy by crippling p53-mediated tumor suppression in a way distinct from previously described mechanisms: it reprograms the p53 network through the EP400 histone acetyltransferase complex and by bromodomain-directed occupancy of the histone variant H2AZ at p53-induced targets, enforcing a repressive chromatin state that prevents p53-mediated transactivation. Importantly, targeting BRD8 in TP53WT GBM remodels chromatin by evicting H2AZ and enhancing chromatin accessibility, enabling p53 to bind and transactivate its targets. This chromatin remodeling cascade (referred to as the “BRD8/p53 epigenetic switch”) re-establishes p53 activity in TP53WT GBM, normalizing gene expression, evoking cell cycle arrest, inhibiting gliomagenesis, and prolonging survival in xenograft models of TP53WT GBM. Our recent work: (i) reveals that BRD8 opposes p53 function in non-malignant brain cells; (ii) shows that the bromodomain of BRD8 is unique amongst the bromodomain-containing protein family, as it is the only one that selectively reprograms the p53 network; and (iii) demonstrates that targeting BRD8 works synergistically with MDM2 inhibition. Our findings present a previously unappreciated mechanism by which cancer cells side-step p53, indicate that targeting BRD8 re-establishes p53-mediated tumor suppression in TP53WT GBM, highlight unique features of the bromodomain of BRD8, and propose therapies using co-inhibition of BRD8 and MDM2 as a dual-level tactic for boosting up p53. Thus, our work sheds light on new principles of chromatin biology and offers new promise for treating patients with this devastating malignancy. (1)Sun et al., 2023 Nature 613 (7942):195-202. Citation Format: Xueqin Sherine Sun, Alea A. Mills. The BRD8/p53 epigenetic switch re-establishes tumor suppression in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1248.

Our understanding of cancer and the key pathways that drive cancer survival has expanded rapidly over the past several decades. However, there are still important challenges that continue to impair patient survival, including our inability to target cancer stem cells (CSCs), metastasis, and drug resistance. The transcription factor p63 is a p53 family member with multiple isoforms that carry out a wide array of functions. Here, we discuss the critical importance of the ΔNp63α isoform in cancer and potential therapeutic strategies to target ΔNp63α expression to impair the CSC population, as well as to prevent metastasis and drug resistance to improve patient survival.

The chromobox-containing protein CBX4 is an important regulator of epithelial cell proliferation and differentiation, and has been implicated in several cancer types. The cancer stem cell (CSC) population is a key driver of metastasis and recurrence. The undifferentiated, plastic state characteristic of CSCs relies on cues from the microenvironment. Cancer-associated fibroblasts (CAFs) are a major component of the microenvironment that can influence the CSC population through the secretion of extracellular matrix and a variety of growth factors. Here we show CBX4 is a critical regulator of the CSC phenotype in squamous cell carcinomas of the skin and hypopharynx. Moreover, CAFs can promote the expression of CBX4 in the CSC population through the secretion of interleukin-6 (IL-6). IL-6 activates JAK/STAT3 signaling to increase ∆Np63α-a key transcription factor that is essential for epithelial stem cell function and the maintenance of proliferative potential that is capable of regulating CBX4. Targeting the JAK/STAT3 axis or CBX4 directly suppresses the aggressive phenotype of CSCs and represents a novel opportunity for therapeutic intervention.

Chromodomain helicase DNA-binding protein 5 (Chd5) is an ATP-dependent chromatin remodeler that promotes neuronal differentiation. However, the mechanism behind the action of Chd5 during neurogenesis is not clearly understood. Here we use transcriptional profiling of cells obtained from Chd5 deficient mice at early and late stages of neuronal differentiation to show that Chd5 regulates neurogenesis by directing stepwise transcriptional changes. During early stages of neurogenesis, Chd5 promotes expression of the proneural transcription factor Six3 to repress Wnt5a, a non-canonical Wnt ligand essential for the maturation of neurons. This previously unappreciated ability of Chd5 to transcriptionally repress neuronal maturation factors is critical for both lineage specification and maturation. Thus, Chd5 facilitates early transcriptional changes in neural stem cells, thereby initiating transcriptional programs essential for neuronal fate specification.

Glioblastoma (GBM) is the most notorious primary brain tumor. The median survival of GBM patients is only about one year and about 95% patients succumb after five years. This gloomy picture has not been improved for decades, even with extensive treatments including surgery, radiotherapy, and chemotherapy. Hence, a better understanding of the mechanisms underlying GBM development may provide new therapeutic opportunities. Primary GBM generally harbors a low mutational load when compared to other human cancers. Even P53—the guardian of the genome that is essentially disabled in nearly all human cancers, remains unmutated in about 71% of GBM cases. Moreover, these P53 wildtype GBM cases are as aggressive as those with P53 mutations. To explore the mechanism by which P53 wildtype GBM thrive in the presence of intact P53, we performed CRISPR screens in a panel of human cancer cell lines using an sgRNA library specifically targeting the functional domains of ~200 chromatin regulators. We discovered that BRD8’s bromodomain—a druggable domain as shown by the tremendous success in preclinical and clinical trial in diverse cancers—is a vulnerability specifically in P53 wildtype GBM cases. Our mechanistic studies demonstrate that BRD8 functions through the EP400 chromatin remodeling complex and hijacks the histone variant H2AZ at P53 target loci, enforcing a compact chromatin state that blocks P53’s accessibility to its targets. We show that targeting the BRD8 bromodomain releases H2AZ, opens up chromatin, engages P53-mediated transactivation, and triggers growth arrest. Consistent with these findings, BRD8 is highly expressed with H2AZ in patient-derived proliferating GBM cells, and is inversely correlated with the expression of P53 targets. Our work solves a long-standing mystery in P53 wildtype GBM, and presents a promising therapeutic target for the majority of GBM patients. Citation Format: Sherine Xueqin Sun, Olaf Klingbeil, Christopher Vakoc, Alea Mills. BRD8-driven EP400 complex hijacks H2AZ to maintain proliferation in glioblastoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4734.

Progressive immune deficiency of aging is characterized by severe thymic atrophy, contracted T cell repertoire, and poor immune function. p63 is critical for the proliferative potential of embryonic and adult stem cells, as well as thymic epithelial cells (TECs). Because p63 null mice experience rapid post-natal lethality due to epidermal and limb morphogenesis defects, studies to define a role for p63 expression in TEC biology focused on embryonic thymus development and in vitro experiments. Since post-natal thymic stromal development and function differs from that of the embryo, we assessed the impact of lineage-restricted p63 loss on pre- and post-natal murine TEC function by generating mice with a loss of p63 function targeted to TEC, termed p63 TECko mice. In adult p63 TECko mice, severe thymic hypoplasia was observed with a lack in a discernable segregation into medullary and cortical compartments and peripheral T cell lymphopenia. This profound thymic defect was seen in both neonatal as well as embryonic p63 TECko mice. In addition to TECs, p63 also plays in important role in the development of stratified epithelium of the skin; lack of p63 results in defects in skin epidermal stratification and differentiation. Interestingly, all adult p63 TECko mice lacked hair follicles despite having normal p63 expression in the skin. Together our results show a critical role of TEC p63 in thymic development and maintenance and show that p63 expression is critical for hair follicle formation.

Enhancer of zeste homolog 2 (EZH2) and SET domain bifurcated 1 (SETDB1, also known as ESET) are oncogenic methyltransferases implicated in a number of human cancers. These enzymes typically function as epigenetic repressors of target genes by methylating histone H3 K27 and H3-K9 residues, respectively. Here, we show that EZH2 and SETDB1 are essential to proliferation in 3 SCC cell lines, HSC-5, FaDu, and Cal33. Additionally, we find both of these proteins highly expressed in an aggressive stem-like SCC sub-population. Depletion of either EZH2 or SETDB1 disrupts these stem-like cells and their associated phenotypes of spheroid formation, invasion, and tumor growth. We show that SETDB1 regulates this SCC stem cell phenotype through cooperation with ΔNp63α, an oncogenic isoform of the p53-related transcription factor p63. Furthermore, EZH2 is upstream of both SETDB1 and ΔNp63α, activating these targets via repression of the tumor suppressor RUNX3. We show that targeting this pathway with inhibitors of EZH2 results in activation of RUNX3 and repression of both SETDB1 and ΔNp63α, antagonizing the SCC cancer stem cell phenotype. This work highlights a novel pathway that drives an aggressive cancer stem cell phenotype and demonstrates a means of pharmacological intervention.

Inhibition of the tumour suppressive function of p53 (encoded by TP53) is paramount for cancer development in humans. However, p53 remains unmutated in the majority of cases of glioblastoma (GBM)-the most common and deadly adult brain malignancy1,2. Thus, how p53-mediated tumour suppression is countered in TP53 wild-type (TP53WT) GBM is unknown. Here we describe a GBM-specific epigenetic mechanism in which the chromatin regulator bromodomain-containing protein 8 (BRD8) maintains H2AZ occupancy at p53 target loci through the EP400 histone acetyltransferase complex. This mechanism causes a repressive chromatin state that prevents transactivation by p53 and sustains proliferation. Notably, targeting the bromodomain of BRD8 displaces H2AZ, enhances chromatin accessibility and engages p53 transactivation. This in turn enforces cell cycle arrest and tumour suppression in TP53WT GBM. In line with these findings, BRD8 is highly expressed with H2AZ in proliferating single cells of patient-derived GBM, and is inversely correlated with CDKN1A, a canonical p53 target that encodes p21 (refs. 3,4). This work identifies BRD8 as a selective epigenetic vulnerability for a malignancy for which treatment has not improved for decades. Moreover, targeting the bromodomain of BRD8 may be a promising therapeutic strategy for patients with TP53WT GBM.

Abstract Bromodomain containing protein 4 (BRD4) plays a critical role in controlling the expression of genes involved in development and cancer. Inactivation of BRD4 inhibits cancer growth, making it a promising anticancer drug target. The cancer stem cell (CSC) population is a key driver of recurrence and metastasis in patients with cancer. Here we show that cancer stem-like cells can be enriched from squamous cell carcinomas (SCC), and that these cells display an aggressive phenotype with enhanced stem cell marker expression, migration, invasion, and tumor growth. BRD4 is highly elevated in this aggressive subpopulation of cells, and its function is critical for these CSC-like properties. Moreover, BRD4 regulates ΔNp63α, a key transcription factor that is essential for epithelial stem cell function that is often overexpressed in cancers. BRD4 regulates an EZH2/STAT3 complex that leads to increased ΔNp63α-mediated transcription. Targeting BRD4 in human SCC reduces ΔNp63α, leading to inhibition of spheroid formation, migration, invasion, and tumor growth. These studies identify a novel BRD4-regulated signaling network in a subpopulation of cancer stem-like cells, elucidating a possible avenue for effective therapeutic intervention. Significance: This study identifies a signaling cascade driven by BRD4 that upregulates ΔNp63α to promote cancer stem-like properties, which has potential therapeutic implications for the treatment of squamous cell carcinomas.

The human 16p11.2 gene locus is a hot spot for copy number variations, which predispose carriers to a range of neuropsychiatric phenotypes. Microduplications of 16p11.2 are associated with autism spectrum disorder (ASD), intellectual disability (ID), and schizophrenia (SZ). Despite the debilitating nature of 16p11.2 duplications, the underlying molecular mechanisms remain poorly understood. Here we performed a comprehensive behavioral characterization of 16p11.2 duplication mice (16p11.2dp/+) and identified social and cognitive deficits reminiscent of ASD and ID phenotypes. 16p11.2dp/+ mice did not exhibit the SZ-related sensorimotor gating deficits, psychostimulant-induced hypersensitivity, or motor impairment. Electrophysiological recordings of 16p11.2dp/+ mice found deficient GABAergic synaptic transmission and elevated neuronal excitability in the prefrontal cortex (PFC), a brain region critical for social and cognitive functions. RNA-sequencing identified genome-wide transcriptional aberrance in the PFC of 16p11.2dp/+ mice, including downregulation of the GABA synapse regulator Npas4. Restoring Npas4 expression in PFC of 16p11.2dp/+ mice ameliorated the social and cognitive deficits and reversed GABAergic synaptic impairment and neuronal hyperexcitability. These findings suggest that prefrontal cortical GABAergic synaptic circuitry and Npas4 are strongly implicated in 16p11.2 duplication pathology, and may represent potential targets for therapeutic intervention in ASD.

ABSTRACT p63 (also known as TP63) is a transcription factor of the p53 family, along with p73. Multiple isoforms of p63 have been discovered and these have diverse functions encompassing a wide array of cell biology. p63 isoforms are implicated in lineage specification, proliferative potential, differentiation, cell death and survival, DNA damage response and metabolism. Furthermore, p63 is linked to human disease states including cancer. p63 is critical to many aspects of cell signaling, and in this Cell science at a glance article and the accompanying poster, we focus on the signaling cascades regulating TAp63 and ΔNp63 isoforms and those that are regulated by TAp63 and ΔNp63, as well the role of p63 in disease.

To study the incidence of tumor suppressor gene (TSG) mutations in men and women with impaired gametogenesis. Gene association analyses were performed on blood samples in two distinct patient populations: males with idiopathic male infertility and females with unexplained diminished ovarian reserve (DOR). The male study group consisted of men with idiopathic azoospermia, oligozoospermia, asthenozoospermia, or teratozoospermia. Age-matched controls were men with normal semen analyses. The female study group consisted of women with unexplained DOR with anti-Müllerian hormone levels ≤ 1.1 ng/mL. Controls were age-matched women with normal ovarian reserve (> 1.1 ng/mL). Fifty-seven male cases (mean age = 38.4; mean sperm count = 15.7 ± 12.1; mean motility = 38.2 ± 24.7) and 37 age-matched controls (mean age = 38.0; mean sperm count = 89.6 ± 37.5; mean motility = 56.2 ± 14.3) were compared. Variants observed in CHD5 were found to be enriched in the study group (p = 0.000107). The incidence of CHD5 mutation c.*3198_*3199insT in the 3′UTR (rs538186680) was significantly higher in cases compared to controls (p = 0.0255). 72 DOR cases (mean age = 38.7; mean AMH = 0.5 ± 0.3; mean FSH = 11.7 ± 12.5) and 48 age-matched controls (mean age = 37.6; mean AMH = 4.1 ± 3.0; mean FSH = 7.1 ± 2.2) were compared. Mutations in CHD5 (c.-140A>C), RB1 (c.1422-18delT, rs70651121), and TP53 (c.376-161A>G, rs75821853) were found at significantly higher frequencies in DOR cases compared to controls (p ≤ 0.05). In addition, 363 variants detected in the DOR patients were not present in the control group. Unexplained impaired gametogenesis in both males and females may be associated with genetic variation in TSGs. TSGs, which play cardinal roles in cell-cycle control, might also be critical for normal spermatogenesis and oogenesis. If validated in larger prospective studies, it is possible that TSGs provide an etiological basis for some patients with impaired gametogenesis.

Sleep abnormalities are common among children with neurodevelopmental disorders. The human chr16p11.2 microdeletion is associated with a range of neurological and neurobehavioral abnormalities. Previous studies of a mouse model of human chr16p11.2 microdeletion (chr16p11.2df/+) have demonstrated pathophysiological changes at the synapses in the hippocampus and striatum; however, the impact of this genetic abnormality on system level brain functions, such as sleep and neural oscillation, has not been adequately investigated. Here, we show that chr16p11.2df/+ mice have altered sleep architecture, with increased wake time and reduced time in rapid eye movement (REM) and non-REM (NREM) sleep. Importantly, several measurements of REM sleep are significantly changed in deletion mice. The REM bout number and the bout number ratio of REM to NREM are decreased in mutant mice, suggesting a deficit in REM-NREM transition. The average REM bout duration is shorter in mutant mice, indicating a defect in REM maintenance. In addition, whole-cell patch clamp recording of the ventrolateral periaqueductal gray (vlPAG)-projecting gamma-aminobutyric acid (GABA)ergic neurons in the lateral paragigantocellular nucleus of ventral medulla of mutant mice reveal that these neurons, which are important for NREM-REM transition and REM maintenance, have hyperpolarized resting membrane potential and increased membrane resistance. These changes in intrinsic membrane properties suggest that these projection-specific neurons of mutant mice are less excitable, and thereby may play a role in deficient NREM-REM transition and REM maintenance. Furthermore, mutant mice exhibit changes in neural oscillation involving multiple frequency classes in several vigilance states. The most significant alterations occur in the theta frequency during wake and REM sleep.

Neural cell fate specification is a multistep process in which stem cells undergo sequential changes in states, giving rise to particular lineages such as neurons and astrocytes. This process is accompanied by dynamic changes of chromatin and in transcription, thereby orchestrating lineage-specific gene expression programs. A pressing question is how these events are interconnected to sculpt cell fate. We show that altered chromatin due to loss of the chromatin remodeler Chd5 causes neural stem cell activation to occur ahead of time. This premature activation is accompanied by transcriptional derepression of ribosomal subunits, enhanced ribosome biogenesis, and increased translation. These untimely events deregulate cell fate decisions, culminating in the generation of excessive numbers of astrocytes at the expense of neurons. By monitoring the proneural factor Mash1, we further show that translational control is crucial for appropriate execution of cell fate specification, thereby providing new insight into the interplay between transcription and translation at the initial stages of neurogenesis.