SMYD5 is a histone H3-specific methyltransferase mediating mono-methylation of histone H3 lysine 36 and 37.

Although post-translational modifications (-PTMs) of some histone H3 lysine residues are well studied, the PTMs of histone H3 lysine 37 in mammalian cells remain largely unknown. In this study, we provide evidence to show that SMYD family member 5 (SMYD5) is a histone H3-specfic methyltransferase that catalyzes mono-methylation of H3 lysine 36 and 37 (H3K36/K37me1) in vitro. The site-mutagenesis analysis shows that a species-conserved histidine in its catalytic SET domain is required for its histone methyltransferase activity. Genetic deletion of Smyd5 in murine embryonic stem cells (mESCs) partially reduces the global histone H3K37me1 level in cells, suggesting SMYD5 is one of histone methyltransferases catalyzing histone H3K37me1 in vivo. Hence, our study reveals that SMYD5 is a histone H3-specific methyltransferase that mediates histone H3K36/K37me1, which provides a biochemical basis for further studying its functions in mammalian cells.

RNF216 is essential for spermatogenesis and male fertility†.

Ring finger protein 216 (RNF216) belongs to the RING family of E3 ubiquitin ligases that are involved in cellular protein degradation. Mutations in human Rnf216 gene have been identified in Gordon Holmes syndrome, which is defined by ataxia, dementia, and hypogonadotropism. However, the gene function of Rnf216 in mammalian species remains unknown. Here, we show that targeted deletion of Rnf216 in mice results in disruption in spermatogenesis and male infertility. RNF216 is not required for female fertility. These findings reveal an essential function of RNF216 in spermatogenesis and male fertility and suggest a critical role for RNF216 in human gonadal development.

Hepatitis B virus X protein-elevated MSL2 modulates hepatitis B virus covalently closed circular DNA by inducing degradation of APOBEC3B to enhance hepatocarcinogenesis.

Chronic hepatitis B virus (HBV) infection is a leading cause in the occurrence of hepatitis B, liver cirrhosis, and liver cancer, in which nuclear HBV covalently closed circular DNA (cccDNA), the genomic form that templates viral transcription and sustains viral persistence, plays crucial roles. In the present study, we explored the hypothesis that HBV X protein (HBx)-elevated male-specific lethal 2 (MSL2) activated HBV replication by modulating cccDNA in hepatoma cells, leading to hepatocarcinogenesis. Immunohistochemical analysis revealed that the expression of MSL2 was positively associated with that of HBV and was increased in the liver tissues of HBV-transgenic mice and clinical HCC patients. Interestingly, microarray profiling identified that MSL2 was associated with those genes responding to the virus. Mechanistically, MSL2 could maintain HBV cccDNA stability through degradation of APOBEC3B by ubiquitylation in hepatoma cells. Above all, HBx accounted for the up-regulation of MSL2 in stably HBx-transfected hepatoma cell lines and liver tissues of HBx-transgenic mice. Luciferase reporter gene assays revealed that the promoter region of MSL2 regulated by HBx was located at nucleotide -1317/-1167 containing FoxA1 binding element. Chromatin immunoprecipitation assay validated that HBx could enhance the binding property of FoxA1 to MSL2 promoter region. HBx up-regulated MSL2 by activating YAP/FoxA1 signaling. Functionally, silencing MSL2 was able to block the growth of hepatoma cells in vitro and in vivo. CONCLUSION: HBx-elevated MSL2 modulates HBV cccDNA in hepatoma cells to promote hepatocarcinogenesis, forming a positive feedback loop of HBx/MSL2/cccDNA/HBV. Our finding uncovers insights into the mechanism by which MSL2 as a promotion factor in host cells selectively activates extrachromosomal DNA. (Hepatology 2017;66:1413-1429).

The oncoprotein HBXIP modulates the feedback loop of MDM2/p53 to enhance the growth of breast cancer.

MDM2 and p53 form a negative feedback loop, in which p53 as a transcription factor positively regulates MDM2 and MDM2 negatively regulates tumor suppressor p53 through promoting its degradation. However, the mechanism of the feedback loop is poorly understood in cancers. We had reported previously that the oncoprotein hepatitis B X-interacting protein (HBXIP) is a key oncoprotein in the development of cancer. Thus, we supposed that HBXIP might be involved in the event. Here, we observed that the expression levels of HBXIP were positively correlated to those of MDM2 in clinical breast cancer tissues. Interestingly, HBXIP was able to up-regulate MDM2 at the levels of mRNA and protein in MCF-7 breast cancer cells. Mechanically, HBXIP increased the promoter activities of MDM2 through directly binding to p53 in the P2 promoter of MDM2. Strikingly, we identified that the acetyltransferase p300 was recruited by HBXIP to p53 in the promoter of MDM2. Moreover, we validated that HBXIP enhanced the p53 degradation mediated by MDM2. Functionally, the knockdown of HBXIP or/and p300 inhibited the proliferation of breast cancer cells in vitro, and the depletion of MDM2 or overexpression of p53 significantly blocked the HBXIP-promoted growth of breast cancer in vitro and in vivo. Thus, we concluded that highly expressed HBXIP accelerates the MDM2-mediated degradation of p53 in breast cancer through modulating the feedback loop of MDM2/p53, resulting in the fast growth of breast cancer cells. Our findings provide new insights into the mechanism of the acceleration of the MDM2/p53 feedback loop in the development of cancer.

Post-transcriptional modulation of protein phosphatase PPP2CA and tumor suppressor PTEN by endogenous siRNA cleaved from hairpin within PTEN mRNA 3'UTR in human liver cells.

AIM: Increasing evidence shows that mRNAs exert regulatory function along with coding proteins. Recently we report that a hairpin within YAP mRNA 3'UTR can modulate the Hippo signaling pathway. PTEN is a tumor suppressor, and is mutated in human cancers. In this study we examined whether PTEN mRNA 3'UTR contained a hairpin structure that could regulate gene regulation at the post-transcriptional level. METHODS: The secondary structure of PTEN mRNA 3'UTR was analyzed using RNAdraw and RNAstructure. Function of hairpin structure derived from the PTEN mRNA 3'UTR was examined using luciferase reporter assay, RT-PCR and Western blotting. RNA-immunoprecipitation (RIP) assay was used to analyze the interaction between PTEN mRNA and microprocessor Drosha and DGCR8. Endogenous siRNA (esiRNA) derived from PTEN mRNA 3'UTR was identified by RT-PCR and rt-PCR, and its target genes were predicted using RNAhybrid. RESULTS: A bioinformatics analysis revealed that PTEN mRNA contained a hairpin structure (termed PTEN-sh) within 3'UTR, which markedly increased the reporter activities of AP-1 and NF-κB in 293T cells. Moreover, treatment with PTEN-sh (1 and 2 µg) dose-dependently inhibited the expression of PTEN in human liver L-O2 cells. RIP assay demonstrated that the microprocessor Drosha and DGCR8 was bound to PTEN-sh in L-O2 cells, leading to the cleavage of PTEN-sh from PTEN mRNA 3'UTR. In addition, microprocessor Dicer was involved in the processing of PTEN-sh. Interestingly, esiRNA (termed PTEN-sh-3p21) cleaved from PTEN-sh was identified in 293T cells and human liver tissues, which was found to target the mRNA 3'UTRs of protein phosphatase PPP2CA and PTEN in L-O2 cells. Treatment of L-O2 or Chang liver cells with PTEN-sh-3p21 (50, 100 nmol/L) promoted the cell proliferation in dose- and time-dependent manners. CONCLUSION: The endogenous siRNA (PTEN-sh-3p21) cleaved from PTEN-sh within PTEN mRNA 3'UTR modulates PPP2CA and PTEN at the post-transcriptional level in liver cells.

MiR-520b suppresses proliferation of hepatoma cells through targeting ten-eleven translocation 1 (TET1) mRNA.

Accumulating evidence indicates that microRNAs are able to act as oncogenes or tumor suppressor genes in human cancer. We previously reported that miR-520b was down-regulated in hepatocellular carcinoma (HCC) and its deregulation was involved in hepatocarcinogenesis. In the present study, we report that miR-520b suppresses cell proliferation in HCC through targeting the ten-eleven translocation 1 (TET1) mRNA. Notably, we identified that miR-520b was able to target 3'-untranslated region (3'UTR) of TET1 mRNA by luciferase reporter gene assays. Then, we revealed that miR-520b was able to reduce the expression of TET1 at the levels of mRNA and protein using reverse transcription-polymerase chain reaction and Western blotting analysis. In terms of function, 5-ethynyl-2-deoxyuridine (EdU) incorporation and colony formation assays demonstrated that the forced miR-520b expression remarkably inhibited proliferation of hepatoma cells, but TET1 overexpression could rescue the inhibition of cell proliferation mediated by miR-520b. Furthermore, anti-miR-520b enhanced proliferation of hepatoma cells, whereas silencing of TET1 abolished anti-miR-520b-induced acceleration of cell proliferation. Then, we validated that the expression levels of miR-520b were negatively related to those of TET1 mRNA in clinical HCC tissues. Thus, we conclude that miR-520b depresses proliferation of liver cancer cells through targeting 3'UTR of TET1 mRNA. Our finding provides new insights into the mechanism of hepatocarcinogenesis.

A hairpin within YAP mRNA 3'UTR functions in regulation at post-transcription level.

The central dogma of gene expression is that DNA is transcribed into messenger RNAs, which in turn serve as the template for protein synthesis. Recently, it has been reported that mRNAs display regulatory roles that rely on their ability to compete for microRNA binding, independent of their protein-coding function. However, the regulatory mechanism of mRNAs remains poorly understood. Here, we report that a hairpin within YAP mRNA 3'untranslated region (3'UTR) functions in regulation at post-transcription level through generating endogenous siRNAs (esiRNAs). Bioinformatics analysis for secondary structure showed that YAP mRNA displayed a hairpin structure (termed standard hairpin, S-hairpin) within its 3'UTR. Surprisingly, we observed that the overexpression of S-hairpin derived from YAP 3'UTR (YAP-sh) increased the luciferase reporter activities of transcriptional factor NF-κB and AP-1 in 293T cells. Moreover, we identified that a fragment from YAP-sh, an esiRNA, was able to target mRNA 3'UTR of NF2 (a member of Hippo-signaling pathway) and YAP mRNA 3'UTR itself in hepatoma cells. Thus, we conclude that the YAP-sh within YAP mRNA 3'UTR may serve as a novel regulatory element, which functions in regulation at post-transcription level. Our finding provides new insights into the mechanism of mRNAs in regulatory function.

Hepatitis B virus X protein promotes human hepatoma cell growth via upregulation of transcription factor AP2α and sphingosine kinase 1.

AIM: Sphingosine kinase 1 (SPHK1) is involved in various cellular functions, including cell growth, migration, apoptosis, cytoskeleton architecture and calcium homoeostasis, etc. As an oncogenic kinase, SPHK1 is associated with the development and progression of cancers. The aim of this study was to investigate whether SPHK1 was involved in hepatocarcinogenesis induced by the hepatitis B virus X protein (HBx). METHODS: The expression of SPHK1 in hepatocellular carcinoma (HCC) tissue and hepatoma cells were measured using qRT-PCR and Western blot analysis. HBx expression levels in hepatoma cells were modulated by transiently transfected with HBx or psi-HBx plasmids. The SPHK1 promoter activity was measured using luciferase reporter gene assay, and the interaction of the transcription factor AP2α with the SPHK1 promoter was studied with chromatin immunoprecipitation assay. The growth of hepatoma cells was evaluated in vitro using MTT and colony formation assays, and in a tumor xenograft model. RESULTS: A positive correlation was found between the mRNA levels of SPHK1 and HBx in 38 clinical HCC samples (r=+0.727, P<0.01). Moreover, the expression of SPHK1 was markedly increased in the liver cancer tissue of HBx-transgenic mice. Overexpressing HBx in normal liver cells LO2 and hepatoma cells HepG2 dose-dependently increased the expression of SPHK1, whereas silencing HBx in HBx-expressing hepatoma cells HepG2-X and HepG2.2.15 suppressed SPHK1 expression. Furthermore, overexpressing HBx in HepG2 cells dose-dependently increased the SPHK1 promoter activity, whereas silencing HBx in HepG2-X cells suppressed this activity. In HepG2-X cells, AP2α was found to directly interact with the SPHK1 promoter, and silencing AP2α suppressed the SPHK1 promoter activity and SPHK1 expression. Silencing HBx in HepG2-X cells abolished the HBx-enhanced proliferation and colony formation in vitro, and tumor growth in vivo. CONCLUSION: HBx upregulates SPHK1 through the transcription factor AP2α, which promotes the growth of human hepatoma cells.

Hepatitis B virus X protein accelerates hepatocarcinogenesis with partner survivin through modulating miR-520b and HBXIP.

BACKGROUND: Hepatitis B virus X protein (HBx) plays crucial roles in hepatocarcinogenesis. However, the underlying mechanism remains elusive. We have reported that HBx is able to up-regulate survivin in hepatocellular carcinoma tissues. The oncopreotein hepatitis B X-interacting protein (HBXIP), a target of miR-520b, is involved in the development of cancer. In this study, we focus on the investigation of hepatocarcinogenesis mediated by HBx. METHODS: The expression of HBx and survivin was examined in the liver tissues of HBx-Tg mice. The effect of HBx/survivin on the growth of LO2-X-S cells was determined by colony formation and transplantation in nude mice. The effect of HBx/survivin on promoter of miR-520b was determined by Western blot analysis, luciferase reporter gene assay, co-immunoprecipitation (co-IP) and chromatin immunoprecipitation (ChIP), respectively. The expression of HBx, survivin and HBXIP was detected by immunohistochemistry and real-time PCR in clinical HCC tissues, respectively. The DNA demethylation of HBXIP promoter was examined. The functional influence of miR-520b and HBXIP on proliferation of hepatoma cells was analyzed by MTT, colony formation, EdU and transplantation in nude mice in vitro and in vivo. RESULTS: In this study, we provided evidence that HBx up-regulated survivin in the liver cancer tissues of HBx-Tg mice aged 18 M. The engineered LO2 cell lines with survivin and/or HBx were successfully established, termed LO2-X-S. MiR-520b was down-regulated in LO2-X-S cells and clinical HCC tissues. Our data revealed that HBx survivin-dependently down-regulated miR-520b through interacting with Sp1 in the cells. HBXIP was highly expressed in LO2-X-S cells, liver cancer tissues of HBx-Tg mice aged 18 M and clinical HCC tissues (75.17%, 112/149). The expression level of HBXIP was positively associated with those of HBx or survivin in clinical HCC tissues. In addition, we showed that HBx survivin-dependently up-regulated HBXIP through inducing demethylation of HBXIP promoter in LO2-X-S cells and clinical HCC tissues. In function, low level miR-520b and high level HBXIP mediated by HBx with partner survivin contributed to the growth of LO2-X-S cells in vitro and in vivo. CONCLUSION: HBx accelerates hepatocarcinogenesis with partner survivin through modulating tumor suppressor miR-520b and oncoprotein HBXIP.

Ribosome heterogeneity in development and disease.

Traditionally viewed as a fixed and homogeneous machinery for protein synthesis, the ribosome is increasingly recognized for its heterogeneity, as indicated by emerging studies highlighting the functional relevance of specialized ribosomes. However, whether ribosome heterogeneity is merely an outcome limited to specific conditions or a pervasive cellular phenomenon remains unclear, and existing evidence on the extensive existence of ribosome heterogeneity is scant. Here, we leveraged existing proteomic data and employed ribosome ratio-omics (RibosomeR), which comprehensively analyzes ribosome protein stoichiometry across various biological samples exhibiting distinct functions, developmental stages, and pathological states. Using the 80S monosome proteomic data, RibosomeR analysis unveils significant ribosome heterogeneity across different tissues, including fat, spleen, liver, kidney, heart, and skeletal muscles. Furthermore, examination of testes at various stages of spermatogenesis reveals distinct RibosomeR signatures during tissue development. Analysis of the whole cell proteomic data finds that RibosomeR undergoes dynamic changes during in vitro neuronal maturation, indicating functional associations with specific molecular aspects of neurodevelopment. In pathological contexts, RibosomeR signatures in gastric tumors demonstrate functional links to pathways associated with tumorigenesis. Additionally, dynamic alterations in RibosomeR are observed in macrophages following immune challenges. Collectively, our investigation across a diverse array of biological samples underscores the presence of ribosome heterogeneity, while previous studies observed functional aspects of ribosome specialization, in cellular function, development, and disease. The RibosomeR barcode serves as a valuable tool for elucidating these complexities.

Elevation of highly up-regulated in liver cancer (HULC) by hepatitis B virus X protein promotes hepatoma cell proliferation via down-regulating p18.

Long noncoding RNAs (lncRNAs) play crucial roles in human cancers. It has been reported that lncRNA highly up-regulated in liver cancer (HULC) is dramatically up-regulated in hepatocellular carcinoma (HCC). Hepatitis B virus X protein (HBx) contributes importantly to the development of HCC. However, the function of HULC in HCC mediated by HBx remains unclear. Here, we report that HULC is involved in HBx-mediated hepatocarcinogenesis. We found that the expression levels of HULC were positively correlated with those of HBx in clinical HCC tissues. Moreover, we revealed that HBx up-regulated HULC in human immortalized normal liver L-O2 cells and hepatoma HepG2 cells. Luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay showed that HBx activated the HULC promoter via cAMP-responsive element-binding protein. We further demonstrated that HULC promoted cell proliferation by methyl thiazolyl tetrazolium, 5-ethynyl-2'-deoxyuridine, colony formation assay, and tumorigenicity assay. Next, we hypothesized that HULC might function through regulating a tumor suppressor gene p18 located near HULC in the same chromosome. We found that the mRNA levels of p18 were inversely correlated with those of HULC in the above clinical HCC specimens. Then, we validated that HULC down-regulated p18, which was involved in the HULC-enhanced cell proliferation in vitro and in vivo. Furthermore, we observed that knockdown of HULC could abolish the HBx-enhanced cell proliferation through up-regulating p18. Thus, we conclude that the up-regulated HULC by HBx promotes proliferation of hepatoma cells through suppressing p18. This finding provides new insight into the roles of lncRNAs in HBx-related hepatocarcinogenesis.

Hepatitis B virus X protein modulates oncogene Yes-associated protein by CREB to promote growth of hepatoma cells.

UNLABELLED: Hepatitis B virus X protein (HBx) plays critical roles in the development of hepatocellular carcinogenesis (HCC). Yes-associated protein (YAP), a downstream effector of the Hippo-signaling pathway, is an important human oncogene. In the present article, we report that YAP is involved in the hepatocarcinogenesis mediated by HBx. We demonstrated that the expression of YAP was dramatically elevated in clinical HCC samples, hepatitis B virus (HBV)-infected hepatoma HepG2.2.15 cell line, and liver cancer tissues of HBx-transgenic mice. Meanwhile, we found that overexpression of HBx resulted in the up-regulation of YAP in stably HBx-transfected HepG2/H7402 hepatoma cell lines, whereas HBx RNA interference reduced YAP expression in a dose-dependent manner in the above-mentioned cell lines, suggesting that HBx up-regulates YAP. Then, we investigated the mechanism underlying the up-regulation of YAP by HBx. Luciferase reporter gene assays revealed that the promoter region of YAP regulated by HBx was located at nt -232/+115 containing cyclic adenosine monophosphate response element-binding protein (CREB) element. Chromatin immunoprecipitation (ChIP) demonstrated that HBx was able to bind to the promoter of YAP, whereas it failed to work when CREB was silenced. Moreover, we confirmed that HBx activated the YAP promoter through CREB by electrophoretic mobility shift assay and luciferase reporter gene assays. Surprisingly, we found that YAP short interfering RNA was able to remarkably block the HBx-enhanced growth of hepatoma cells in vivo and in vitro. CONCLUSION: YAP is a key driver gene in HBx-induced hepatocarcinogenesis in a CREB-dependent manner. YAP may serve as a novel target in HBV-associated HCC therapy.

Ribosome Heterogeneity in Development and Disease.

The functional ribosome is composed of ∼80 ribosome proteins. With the intensity-based absolute quantification (iBAQ) value, we calculate the stoichiometry ratio of each ribosome protein. We analyze the ribosome ratio-omics (Ribosome R ), which reflects the holistic signature of ribosome composition, in various biological samples with distinct functions, developmental stages, and pathological outcomes. The Ribosome R reveals significant ribosome heterogeneity among different tissues of fat, spleen, liver, kidney, heart, and skeletal muscles. During tissue development, testes at various stages of spermatogenesis show distinct Ribosome R signatures. During in vitro neuronal maturation, the Ribosome R changes reveal functional association with certain molecular aspects of neurodevelopment. Regarding ribosome heterogeneity associated with pathological conditions, the Ribosome R signature of gastric tumors is functionally linked to pathways associated with tumorigenesis. Moreover, the Ribosome R undergoes dynamic changes in macrophages following immune challenges. Taken together, with the examination of a broad spectrum of biological samples, the Ribosome R barcode reveals ribosome heterogeneity and specialization in cell function, development, and disease. One-Sentence Summary: Ratio-omics signature of ribosome deciphers functionally relevant heterogeneity in development and disease.

A glimpse of the connection between PPARγ and macrophage.

Nuclear receptors are ligand-regulated transcription factors that regulate vast cellular activities and serve as an important class of drug targets. Among them, peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor family and have been extensively studied for their roles in metabolism, differentiation, development, and cancer, among others. Recently, there has been considerable interest in understanding and defining the function of PPARs and their agonists in regulating innate and adaptive immune responses and their pharmacological potential in combating chronic inflammatory diseases. In this review, we focus on emerging evidence for the potential role of PPARγ in macrophage biology, which is the prior innate immune executive in metabolic and tissue homeostasis. We also discuss the role of PPARγ as a regulator of macrophage function in inflammatory diseases. Lastly, we discuss the possible application of PPARγ antagonists in metabolic pathologies.

Neural Hyperactivity Is a Core Pathophysiological Change Induced by Deletion of a High Autism Risk Gene Ash1L in the Mouse Brain.

ASH1L is one of the highest risk genes associated with autism spectrum disorder (ASD) and intellectual disability (ID). Our recent studies demonstrate that loss of Ash1l in the mouse brain is sufficient to induce ASD/ID-like behavioral and cognitive deficits, suggesting that disruptive ASH1L mutations are likely to have a positive correlation with ASD/ID genesis. However, the core pathophysiological changes in the Ash1l-deficient brain remain largely unknown. Here we show that loss of Ash1l in the mouse brain causes locomotor hyperactivity, high metabolic activity, and hyperactivity-related disturbed sleep and lipid metabolic changes. In addition, the mutant mice display lower thresholds for the convulsant reagent-induced epilepsy and increased neuronal activities in multiple brain regions. Thus, our current study reveals that neural hyperactivity is a core pathophysiological change in the Ash1l-deficient mouse brain, which may function as a brain-level mechanism leading to the Ash1l-deletion-induced brain functional abnormalities and autistic-like behavioral deficits.

Kdm6b Haploinsufficiency Causes ASD/ADHD-Like Behavioral Deficits in Mice.

Autism spectrum disorder (ASD) is a neurodevelopmental disease that has intellectual disability (ID) and attention-deficit/hyperactivity disorder (ADHD) as its common comorbidities. Recent genetic and clinical studies report that KDM6B, a gene encoding a histone H3 lysine 27-specific demethylase, is one of the highest ASD risk genes. However, the relationship between KDM6B mutations and neurodevelopmental diseases remains unclear. Here we use an animal model to show that genetic deletion of one Kdm6b allele in mice leads to autistic-like impaired sociability and object recognition memory. In addition, the mutant mice display markedly increased locomotor activity and impulsivity, two ADHD-like behavioral traits that are ameliorated by methylphenidate treatment. Thus, our study not only uncovers a potential causal link between disruptive KDM6B mutations and ASD/ADHD-like behavioral deficits but also provides a new mouse model for studying the cellular and molecular mechanisms underlying the Kdm6b-mutation-related neurodevelopmental diseases.

Impaired KDM2B-mediated PRC1 recruitment to chromatin causes defective neural stem cell self-renewal and ASD/ID-like behaviors.

Recent clinical studies report that chromosomal 12q24.31 microdeletions are associated with autism spectrum disorder (ASD) and intellectual disability (ID). However, the causality and underlying mechanisms linking 12q24.31 microdeletions to ASD/ID remain undetermined. Here we show Kdm2b, one gene located in chromosomal 12q24.31, plays a critical role in maintaining neural stem cells (NSCs) in the mouse brain. Loss of the CxxC-ZF domain of KDM2B impairs its function in recruiting Polycomb repressive complex 1 (PRC1) to chromatin, resulting in de-repression of genes involved in cell apoptosis, cell-cycle arrest, NSC senescence, and loss of NSC populations in the brain. Of importance, the Kdm2b mutation is sufficient to induce ASD/ID-like behavioral and memory deficits. Thus, our study reveals a critical role of KDM2B in normal brain development, a causality between the Kdm2b mutation and ASD/ID-like phenotypes in mice, and potential molecular mechanisms linking the function of KDM2B-PRC1 in transcriptional regulation to the 12q24.31 microdeletion-associated ASD/ID.

Vorinostat, a histone deacetylase inhibitor, ameliorates the sociability and cognitive memory in an Ash1L-deletion-induced ASD/ID mouse model.

Autism spectrum disorder (ASD) and intellectual disability (ID) are neurodevelopmental diseases associated with various gene mutations. Previous genetic and clinical studies reported that ASH1L is a high ASD risk gene identified in human patients. Our recent study used a mouse model to demonstrate that loss of ASH1L in the developing mouse brain was sufficient to cause multiple developmental defects, core autistic-like behaviors, and impaired cognitive memory, suggesting that the disruptive ASH1L mutations are the causative drivers leading the human ASD/ID genesis. Using this Ash1L-deletion-induced ASD/ID mouse model, here we showed that postnatal administration of vorinostat (SAHA), a histone deacetylase inhibitor (HDACi), significantly ameliorated both ASD-like behaviors and ID-like cognitive memory deficit. Thus, our study demonstrates that SAHA is a promising reagent for the pharmacological treatment of core ASD/ID behavioral and memory deficits caused by disruptive ASH1L mutations.

Histone H3K36me2-Specific Methyltransferase ASH1L Promotes MLL-AF9-Induced Leukemogenesis.

ASH1L and MLL1 are two histone methyltransferases that facilitate transcriptional activation during normal development. However, the roles of ASH1L and its enzymatic activity in the development of MLL-rearranged leukemias are not fully elucidated in Ash1L gene knockout animal models. In this study, we used an Ash1L conditional knockout mouse model to show that loss of ASH1L in hematopoietic progenitor cells impaired the initiation of MLL-AF9-induced leukemic transformation in vitro. Furthermore, genetic deletion of ASH1L in the MLL-AF9-transformed cells impaired the maintenance of leukemic cells in vitro and largely blocked the leukemia progression in vivo. Importantly, the loss of ASH1L function in the Ash1L-deleted cells could be rescued by wild-type but not the catalytic-dead mutant ASH1L, suggesting the enzymatic activity of ASH1L was required for its function in promoting MLL-AF9-induced leukemic transformation. At the molecular level, ASH1L enhanced the MLL-AF9 target gene expression by directly binding to the gene promoters and modifying the local histone H3K36me2 levels. Thus, our study revealed the critical functions of ASH1L in promoting the MLL-AF9-induced leukemogenesis, which provides a molecular basis for targeting ASH1L and its enzymatic activity to treat MLL-AF9-induced leukemias.