Functions In Epigenetic Regulation Research Articles

Abstract C093: Epigenetic insights and gene expression in African pan genome contig sequences

Abstract An often-overlooked component in our cancer genomics workflows is the reference genome. While most genomics analytical tools and findings are based on reference builds GRCh37 and GRCh38, these references are largely Eurocentric, and their representativeness among diverse populations has not been studied comprehensively. A previously published study conducted deep whole genome sequencing of over 900 individuals of African ancestry, where they revealed ∼296 million unique base pairs, assembled into 125,715 African Pan Genome (APG) contig sequences that are not represented in the reference genome. To further characterize these APG contig sequences, we sought to determine the epigenetic and expression potential of these sequences. We have previously reported preliminary efforts to characterize the unexplored epigenetic potential across the 125,715 APG contig sequences, where we have utilized Emboss CpG plot for CpG island prediction. Across all contig sequences, we identified 8,353 potential CpG islands across 6,352 contig sequences, where contigs had 1 to 9 predicted CpG islands. Taken together ∼5% of all APG contigs contained at least 1 predicted CpG island. To determine the expression potential of these contigs, we mapped RNAseq reads from an African ancestry-enriched triple negative breast cancer cohort to APG contigs that previously failed to map to the reference genome. Approximately 9% of APG contigs had transcriptomic reads mapping, and 1106 APG contigs had both reads mapping and predicted CpG islands. Given our RNAseq mapping from our African ancestry enriched cohort, we have begun to explore differential expression measures among contigs by African ancestry population groups, highlighting the potential for differential regulation at these understudied loci. Since the publication of the APG contig sequences, the recent telomere-to-telomere (T2T) reference has filled the gaps of GRCh37 and GRCh38, however, is even less diverse. With T2T containing novel sequences that were not present at the time the APG contigs were assembled, we performed BLASTn queries of APG contigs to the T2T genome, where preliminary analysis shows ∼17% fail to map to T2T. For those with BLASTn mapping results, we are currently assessing the coverage and identity of the mapping results to evaluate the alignment. In conclusion, these APG contig sequences harbor potential epigenetic regulatory function and expressed sequences not represented in our standard reference genomes. While some APG contig sequences are represented in the newer T2T genome, preliminary investigations show that these APG contig sequences map to the T2T genome in regions novel from GRCh37 and GRCh38. As we continue to explore these APG contig sequences, we may find ancestry-specific regulatory mechanisms not yet described. Citation Format: Rachel Martini, Kyriaki Founta, Sebastian Maurice, Jason White, Lisa Newman, Onyinye Balogun, Nyasha Chambwe, Melissa Davis. Epigenetic insights and gene expression in African pan genome contig sequences [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C093.

LncRNA HOTAIR and Cardiovascular diseases.

Cardiovascular diseases (CVDs) a major contributor to global mortality rates, with a steadily rising prevalence observed across the world. Understanding the molecular mechanisms that underlie the signaling pathways implicated in the pathogenesis of CVDs represents a salient and advantageous avenue toward the development of precision and targeted therapeutics. A recent development in CVDs research is the discovery of long non-coding RNAs (lncRNAs), which are now understood to have crucial roles in the onset and development of several pathophysiological processes. The distinct expression patterns exhibited by lncRNAs in various CVDs contexts, present a significant opportunity for their utilization as both biomarkers and targets for therapeutic intervention. Among the various identified lncRNAs, HOX antisense intergenic RNA (HOTAIR) functions as signaling molecules that are significantly implicated in the pathogenesis of cardiovascular disorders in response to risk factors. HOTAIR has been observed to circulate within the bloodstream and possesses an integral epigenetic regulatory function in the transcriptional pathways of many diseases. Recent studies have suggested that HOTAIR offers promise as a biomarker for the detection and treatment of CVDs. The investigation on HOTAIR's role in CVDs, however, is still in its early phases. The goal of the current study is to give a thorough overview of recent developments in the field of analyzing the molecular mechanism of HOTAIR in controlling the pathophysiological processes of CVDs as well as its possible therapeutic uses.

Expanding the Neuropsychological Phenotype of KAT6B Disorders: Overlapping Features with KAT6A Syndrome.

KAT6B and KAT6A belong to the MYST family of lysine acetyltransferases, and regulate gene expression via histone modification. Although both proteins share similar structure and epigenetic regulatory functions, it remains unclear if KAT6A/6B mutation disorders, both very rare conditions, yield the same neurocognitive presentation and thus benefit from similar treatment approaches. This study provides a preliminary overview of neuropsychological functioning of 13 individuals with KAT6B disorder (Mean age = 9.01 years, SD = 5.46), which was compared to that of a recently published sample of 15 individuals with KAT6A syndrome (Mean age = 10.32 years, SD = 4.12). Participants completed a neuropsychological test battery to assess non-verbal cognition, and caregivers completed a series of standardized rating inventories to assess daily behavioral functioning. Results reveal those with KAT6B disorders present with severe adaptive deficits (92.3%) and autism-related behaviors (83.3%), juxtaposed with relatively low concerns with externalizing behaviors (7.6%), a pattern shared by the KAT6A group. Those with KAT6B disorders present with high levels of autistic features, including reduced affiliative interest, whereas social motivation is less affected within the KAT6A group. Overall, the levels of impairment in nonverbal cognition and receptive language were comparable among those with KAT6B disorders, a trend also seen in the KAT6A group. In brief, KAT6B and KAT6A disorders yield analogous neuropsychological profiles. Findings implicate common molecular pathophysiological mechanisms for these epigenetic disorders, such that similar therapies may have shared effect across diseases.

Epigenetic and gene regulatory functions of small RNAs.

In this review article, I summarize the intervention I made during the "Hommage à François Gros" held at the Institut Pasteur in Paris on the 25th of April, 2023. I discuss how the discovery of the existence of an RNA intermediate between genetic information and protein translation has changed our perspective on the role of RNA in gene regulation in these past years. I also discuss new emerging paradigms, highlighting the role of RNA in heritable information similar to the well-known DNA function.

Development of Complementary Photo-arginine/lysine to Promote Discovery of Arg/Lys hPTMs Interactomes.

Arginine and lysine, frequently appearing as a pair on histones, have been proven to carry diverse modifications and execute various epigenetic regulatory functions. However, the most context-specific and transient effectors of these marks, while significant, have evaded study as detection methods have thus far not reached a standard to capture these ephemeral events. Herein, a pair of complementary photo-arginine/δ-photo-lysine (R-dz/K-dz) probes is developed and involve these into histone peptide, nucleosome, and chromatin substrates to capture and explore the interactomes of Arg and Lys hPTMs. By means of these developed tools, this study identifies that H3R2me2a can recruit MutS protein homolog 6 (MSH6), otherwise repelDouble PHD fingers 2 (DPF2), Retinoblastoma binding protein 4/7 (RBBP4/7). And it is disclosed that H3R2me2a inhibits the chromatin remodeling activity of the cBAF complex by blocking the interaction between DPF2 (one component of cBAF) and the nucleosome. In addition, the novel pairs of H4K5 PTMs and respective readers are highlighted, namely H4K5me-Lethal(3)malignant brain tumor-like protein 2 (L3MBTL2), H4K5me2-L3MBTL2, and H4K5acK8ac-YEATS domain-containing protein 4 (YEATS4). These powerful tools pave the way for future investigation of related epigenetic mechanisms including but not limited to hPTMs.

BRD4-binding enhancer promotes CRC progression by interacting with YY1 to activate the Wnt pathway through upregulation of TCF7L2

Colorectal carcinoma (CRC), one of the most life-threatening cancer types, is associated with aberrant expression of epigenetic modifiers and activation of the Wnt pathway. However, the role of epigenetic regulators in driving cancer cell proliferation and their potential as therapeutic targets affecting the Wnt pathway remain unclear. In this study, BRD4 was found to promote the progression of CRC both in vitro and in vivo. The expression of BRD4 correlated with shortened CRC patient survival. In addition, BRD4 function was strongly correlated with the Wnt pathway, but rather through regulation of TCF7L2 at transcriptional levels. BRD4 and H3K27ac have overlapping occupancies in the cis-regulatory elements of TCF7L2, suggesting enhancer-based epigenetic regulation. Numerous YY1 binding sites were found in the abovementioned region. YY1 recruited BRD4 to bind to cis-regulatory elements of TCF7L2, thereby regulating the expression of TCF7L2. Altogether, this study validates that BRD4 performs a canonical epigenetic regulatory function in CRC and can be used in the treatment of Wnt pathway-dependent CRC or other malignancies with clinically available bromodomain inhibitors.

SETD2 controls m6A modification of transcriptome and regulates the molecular oncogenesis of glioma.

SETD2 is known for its epigenetic regulatory function and a frequently mutated gene in multiple cancers. Recently, it has been inferred that SETD2 regulates m6A mRNA methylation (epitranscriptome) via H3K36me3. The m6A RNA methylation is vital for tumor maintenance, self-renewal, and tumorigenesis. RNA modifications are executed by writers, readers, and erasers. m6A modifiers work along with the molecular cues, H3K36me3, laid down by SETD2. A positive correlation observed between SETD2 and RNA modifiers signifies their direct role in epitranscriptomics. Hence, understanding the epitranscriptomics will provide a new facet for molecular oncogenesis. Glioma is a common, malignant grade IV tumor with limited therapeutic alternatives and a poor prognosis. Yet, its function in glioma is not fully defined.Inthe present study, thorough investigations were done in the m6A RNA methylation regulators expression, the molecular pathways leading to tumor progression, and their respective outcomes in SETD2-mediated RNA methylation. In vitro analysis reveals that SETD2 knockdown positively affected the oncogenic properties of the glioma cell line and a global reduction in m6A levels in the transcriptome. The reduction of m6A in the transcriptome can be attributed to the decreased expression of METTL3 and METTL14. Therefore, we conclude that SETD2-mediated m6A modifications are crucial for glioma oncogenesis.

The Transcription Factor NRF2 Has Epigenetic Regulatory Functions Modulating HDACs, DNMTs, and miRNA Biogenesis.

The epigenetic regulation of gene expression is a complex and tightly regulated process that defines cellular identity and is associated with health and disease processes. Oxidative stress is capable of inducing epigenetic modifications. The transcription factor NRF2 (nuclear factor erythroid-derived 2-like 2) is a master regulator of cellular homeostasis, regulating genes bearing antioxidant response elements (AREs) in their promoters. Here, we report the identification of ARE sequences in the promoter regions of genes encoding several epigenetic regulatory factors, such as histone deacetylases (HDACs), DNA methyltransferases (DNMTs), and proteins involved in microRNA biogenesis. In this research, we study this possibility by integrating bioinformatic, genetic, pharmacological, and molecular approaches. We found ARE sequences in the promoter regions of genes encoding several HDACs, DNMTs, and proteins involved in miRNA biogenesis. We confirmed that NRF2 regulates the production of these genes by studying NRF2-deficient cells and cells treated with dimethyl fumarate (DMF), an inducer of the NRF2 signaling pathway. In addition, we found that NRF2 could be involved in the target RNA-dependent microRNA degradation (TDMD) of miR-155-5p through its interaction with Nfe2l2 mRNA. Our data indicate that NRF2 has an epigenetic regulatory function, complementing its traditional function and expanding the regulatory dimensions that should be considered when developing NRF2-centered therapeutic strategies.

α-Synuclein and Mechanisms of Epigenetic Regulation.

Synucleinopathies are a group of neurodegenerative diseases with common pathological lesions associated with the excessive accumulation and abnormal intracellular deposition of toxic species of α-synuclein. The shared clinical features are chronic progressive decline of motor, cognitive, and behavioral functions. These disorders include Parkinson's disease, dementia with Lewy body, and multiple system atrophy. Vigorous research in the mechanisms of pathology of these illnesses is currently under way to find disease-modifying treatment and molecular markers for early diagnosis. α-Synuclein is a prone-to-aggregate, small amyloidogenic protein with multiple roles in synaptic vesicle trafficking, neurotransmitter release, and intracellular signaling events. Its expression is controlled by several mechanisms, one of which is epigenetic regulation. When transmitted to the nucleus, α-synuclein binds to DNA and histones and participates in epigenetic regulatory functions controlling specific gene transcription. Here, we discuss the various aspects of α-synuclein involvement in epigenetic regulation in health and diseases.

UHRF2 regulates cell cycle, epigenetics and gene expression to control the timing of retinal progenitor and ganglion cell differentiation.

Ubiquitin-like, containing PHD and RING finger domains 2 (UHRF2) regulates cell cycle and binds 5-hydroxymethylcytosine (5hmC) to promote completion of DNA demethylation. Uhrf2-/- mice are without gross phenotypic defects; however, the cell cycle and epigenetic regulatory functions of Uhrf2 during retinal tissue development are unclear. Retinal progenitor cells (RPCs) produce all retinal neurons and Müller glia in a predictable sequence controlled by the complex interplay between extrinsic signaling, cell cycle, epigenetic changes and cell-specific transcription factor activation. In this study, we find that UHRF2 accumulates in RPCs, and its conditional deletion from mouse RPCs reduced 5hmC, altered gene expressions and disrupted retinal cell proliferation and differentiation. Retinal ganglion cells were overproduced in Uhrf2-deficient retinae at the expense of VSX2+ RPCs. Most other cell types were transiently delayed in differentiation. Expression of each member of the Tet3/Uhrf2/Tdg active demethylation pathway was reduced in Uhrf2-deficient retinae, consistent with locally reduced 5hmC in their gene bodies. This study highlights a novel role of UHRF2 in controlling the transition from RPCs to differentiated cell by regulating cell cycle, epigenetic and gene expression decisions.

Phytochemicals as Potential Epidrugs in Type 2 Diabetes Mellitus.

Type 2 diabetes Mellitus (T2DM) prevalence has significantly increased worldwide in recent years due to population age, obesity, and modern sedentary lifestyles. The projections estimate that 439 million people will be diabetic in 2030. T2DM is characterized by an impaired β-pancreatic cell function and insulin secretion, hyperglycemia and insulin resistance, and recently the epigenetic regulation of β-pancreatic cells differentiation has been underlined as being involved. It is currently known that several bioactive molecules, widely abundant in plants used as food or infusions, have a key role in histone modification and DNA methylation, and constituted potential epidrugs candidates against T2DM. In this sense, in this review the epigenetic mechanisms involved in T2DM and protein targets are reviewed, with special focus in studies addressing the potential use of phytochemicals as epidrugs that prevent and/or control T2DM in vivo and in vitro. As main findings, and although some controversial results have been found, bioactive molecules with epigenetic regulatory function, appear to be a potential replacement/complementary therapy of pharmacological hypoglycemic drugs, with minimal side effects. Indeed, natural epidrugs have shown to prevent or delay the T2DM development and the morbidity associated to dysfunction of blood vessels, eyes and kidneys due to sustained hyperglycemia in T2DM patients.

Identification of the Roles of Chromobox Family Members in Gastric Cancer: A Study Based on Multiple Datasets.

Background As the important components in polycomb repressive complexes 1 (PRC1) and heterochromatin protein 1 (HP1), Chromobox (CBX) family members are involved in epigenetic regulatory function, transcriptional repression, and other cellular metabolisms. Increasing studies have indicated significant associations between CBX and tumorigenesis, which is a progression in different types of cancers. However, the information about the roles of each CBX in gastric cancer is extremely limited. Methods We explored CBX mRNA expression, corrections with clinicopathological parameters, protein expression, prognostic values, enrichment analysis with several databases including Oncomine, Human Protein Atlas, UALCAN, Kaplan-Meier plotter, cBioPortal, GeneMANIA, and Enrichr. Results In our study, comparing to the normal tissues, higher mRNA expression of CBX1/2/3/4/5/8 and lower mRNA expression of CBX7 were found in GC tissues while upregulations of CBX1/2/3/4/5/8 and downregulations of CBX7 were indicated to be significantly correlated to the nodal metastasis status and individual cancer stages in GC patients. As for protein level, the expression of CBX2/3/4/5/6 was higher and the expression of CBX7 was lower in the GC tissues than those in the normal. What is more, higher mRNA expression of CBX1/5/6/8 and lower mRNA expression of CBX7 were markedly correlated to poor outcomes of OS and FP in GC patients. Besides, high mutation rate of CBXs (42%) was observed in GC patients. Conclusions We suggest that CBX5/7 may serve as potential therapeutic targets for GC while CBX1/8 may serve as potential prognostic indicators for GC.

Epigenetic Mechanisms of LncRNAs Binding to Protein in Carcinogenesis.

Simple SummaryThe functional analysis of lncRNA, which has recently been investigated in various fields of biological research, is critical to understanding the delicate control of cells and the occurrence of diseases. The interaction between proteins and lncRNA, which has been found to be a major mechanism, has been reported to play an important role in cancer development and progress. This review thus organized the lncRNAs and related proteins involved in the cancer process, from carcinogenesis to metastasis and resistance to chemotherapy, to better understand cancer and to further develop new treatments for it. This will provide a new perspective on clinical cancer diagnosis, prognosis, and treatment.Epigenetic dysregulation is an important feature for cancer initiation and progression. Long non-coding RNAs (lncRNAs) are transcripts that stably present as RNA forms with no translated protein and have lengths larger than 200 nucleotides. LncRNA can epigenetically regulate either oncogenes or tumor suppressor genes. Nowadays, the combined research of lncRNA plus protein analysis is gaining more attention. LncRNA controls gene expression directly by binding to transcription factors of target genes and indirectly by complexing with other proteins to bind to target proteins and cause protein degradation, reduced protein stability, or interference with the binding of other proteins. Various studies have indicated that lncRNA contributes to cancer development by modulating genes epigenetically and studies have been done to determine which proteins are combined with lncRNA and contribute to cancer development. In this review, we look in depth at the epigenetic regulatory function of lncRNAs that are capable of complexing with other proteins in cancer development.

A regulatory role for CHD2 in myelopoiesis

ABSTRACT The transcriptional program that dictates haematopoietic cell fate and differentiation requires an epigenetic regulatory and memory function, provided by a network of epigenetic factors that regulate DNA methylation, post-translational histone modifications and chromatin structure. Disturbed epigenetic regulation causes perturbations in the blood cell differentiation program that results in various types of haematopoietic disorders. Thus, accurate epigenetic regulation is essential for functional haematopoiesis. In this study, we used a CRISPR-Cas9 screening approach to identify new epigenetic regulators in myeloid differentiation. We designed a Chromatin-UMI CRISPR guide library targeting 1092 epigenetic regulators. Phorbol 12-myristate 13-acetate (PMA) treatment of the chronic myeloid leukaemia cell line K-562 was used as a megakaryocytic myeloid differentiation model. Both previously described developmental epigenetic regulators and novel factors were identified in our screen. In this study, we validated and characterized a role for the chromatin remodeller CHD2 in myeloid proliferation and megakaryocytic differentiation.

Biology of t(6;11) Fusion Proteins and Their Role in MLL-Rearranged Acute Leukemia Lineage Determination

Chromosomal translocations are genetic rearrangements where a chromosomal segment is transferred to a non-homologous chromosome which give rise to novel chimeras. Chromosomal rearrangements play a significant role in the development of acute leukemias (acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML)). Chromosomal translocation events occurring at 11q23 involving the KMT2A or Mixed-Lineage Leukemia (MLL) gene (n=102) can be diagnosed in about 5-10% of all acute leukemia patients (Marschalek Ann Lab Med 2016), especially prevalent in infant acute leukemias (up to 70% of cases). Different chromosomal translocation partner genes (such as AF4, AF6, AF9orENL and ELL) account for the majority of leukemia cases and have their genomic breakpoints within a major breakpoint cluster region (BCR intron 9-11; Meyer et. al. Leukemia 2018). Some rearrangements are specifically associated with particular disease phenotype e.g. the majority of ALL patients (~ 90%) are mainly caused by the following gene fusions, MLL-AF4, MLL-AF9, MLL-ENL. We are interested in a rare but yet drastic chromosomal translocation t(6;11)(q27;q23) which fuses KMT2A/MLL to Afadin (AFDN/AF6) gene. This chromosomal rearrangement has a very poor prognosis (survival-rate is ~10%) and is predominantly diagnosed in patients with high-risk AML. In this project, we investigate the molecular consequences of two different MLL-AF6 fusions and their corresponding reciprocal AF6-MLL fusions. MLL-AF6 fusions are mainly occurring within MLL intron 9 to 11 and are associated with an AML disease phenotype, while the same fusion occurring within the minor breakpoints region in MLL intron 21 until exon (ex) 24 are mainly diagnosed with T-ALL (T-cell acute lymphoblastic leukemia) disease phenotype. The molecular mechanism that determines the resulting disease phenotype is yet unknown. Therefore, we cloned all of these t(6;11) fusion proteins in order to investigate the functional consequences of the two different breakpoints (MLLex1-9::AF6ex2-30, AF6ex1::MLLex10-37; MLLex1-21::AF6ex2-30, AF6ex1::MLLex22-37). All 4 fusion genes were introduced into our inducible Sleeping Beauty system (Ivics et. al. Mobile DNA 2010; Kowarz et. al. Biotechnol J. 2015) and stably transfected reporter cell lines. Basically, these 4 fusion proteins differ only in the presence or absence of their Plant homeodomain 1-3/Bromodomain (PHD1-3/BD) domain (see Figure 1). The PHD domain regulates the epigenetic and transcriptional regulatory functions of wildtype MLL. Subsequently, we analyzed gene expression differences by the MACE-Seq (Massive Analyses of cDNA Ends). MACE data revealed fundamental differences in gene expression profiles when analyzing the two different sets of t(6;11) fusion genes. The resulting profiles have similarities to either AML or T-ALL and might give a rational explanation for the different lineages in these t(6;11) patients. Altogether, these results notably indicate that our study will provide a novel insight into this type of high-risk leukemia and subsequently will be useful for developing of novel and appropriate therapeutic strategies against acute leukemia. Disclosures No relevant conflicts of interest to declare.

MDR: an integrative DNA N6-methyladenine and N4-methylcytosine modification database for Rosaceae

Eukaryotic DNA methylation has been receiving increasing attention for its crucial epigenetic regulatory function. The recently developed single-molecule real-time (SMRT) sequencing technology provides an efficient way to detect DNA N6-methyladenine (6mA) and N4-methylcytosine (4mC) modifications at a single-nucleotide resolution. The family Rosaceae contains horticultural plants with a wide range of economic importance. However, little is currently known regarding the genome-wide distribution patterns and functions of 6mA and 4mC modifications in the Rosaceae. In this study, we present an integrated DNA 6mA and 4mC modification database for the Rosaceae (MDR, http://mdr.xieslab.org). MDR, the first repository for displaying and storing DNA 6mA and 4mC methylomes from SMRT sequencing data sets for Rosaceae, includes meta and statistical information, methylation densities, Gene Ontology enrichment analyses, and genome search and browse for methylated sites in NCBI. MDR provides important information regarding DNA 6mA and 4mC methylation and may help users better understand epigenetic modifications in the family Rosaceae.

LncRNA Riken-201 and Riken-203 modulates neural development by regulating the Sox6 through sequestering miRNAs.

ObjectivesLong non‐coding RNAs (LncRNAs) play important roles in epigenetic regulatory function during the development processes. In this study, we found that through alternative splicing, LncRNA C130071C03Riken variants Riken‐201 (Riken‐201) and Riken‐203 (Riken‐203) are both expressed highly in brain, and increase gradually during neural differentiation. However, the function of Rik‐201 and Rik‐203 is unknown.Materials and methodsEmbryonic stem cells (ESCs); RNA sequencing; gene expression of mRNAs, LncRNAs and miRNAs; over‐expression and RNA interference of genes; flow cytometry; real‐time quantity PCR; and Western blot were used in the studies. RNA pull‐down assay and PCR were employed to detect any miRNA that attached to Rik‐201 and Rik‐203. The binding of miRNA with mRNA of Sox6 was presented by the luciferase assay.ResultsRepression of Rik‐201 and Rik‐203 inhibited neural differentiation from mouse embryonic stem cells. Moreover, Rik‐201 and Rik‐203 functioned as the competing endogenous RNA (ceRNA) to repress the function of miR‐96 and miR‐467a‐3p, respectively, and modulate the expression of Sox6 to further regulate neural differentiation. Knockout of the Rik‐203 and Rik‐201 induced high ratio of brain developmental retardation. Further we found that C/EBPβ might potentially activated the transcription of Rik‐201 and Rik‐203.ConclusionsThese findings identify the functional role of Rik‐201 and Rik‐203 in facilitating neural differentiation and further brain development, and elucidate the underlying miRNAs‐Sox6‐associated molecular mechanisms.

Imbalance of the reciprocally inhibitory loop between the ubiquitin-specific protease USP43 and EGFR/PI3K/AKT drives breast carcinogenesis.

Hyperactivation of EGFR/PI3K/AKT is a prominent feature of various human cancers. Thus, understanding how this molecular cascade is balanced is of great importance. We report here that the ubiquitin-specific protease USP43 is physically associated with the chromatin remodeling NuRD complex and catalyzes H2BK120 deubiquitination. Functionally this coordinates the NuRD complex to repress a cohort of genes, including EGFR, which are critically involved in cell proliferation and carcinogenesis. We show that USP43 strongly suppresses the growth and metastasis of breast cancer in vivo. Interestingly, USP43 also exists in the cytoplasm, where it is phosphorylated by AKT, enabling its binding to the 14-3-3β/ε heterodimer and sequestration in the cytoplasm. Significantly, hyperactivation of EGFR/PI3K/AKT in breast cancer is associated with the cytoplasmic retention of USP43 and thus, the inhibition of its transcriptional regulatory function. Moreover, cancer-associated mutations of USP43 affect its subcellular localization and/or epigenetic regulatory functions. Nuclear USP43 is significantly reduced in breast carcinomas and is associated with EGFR accumulation and AKT hyperactivation. A low level of nuclear USP43 correlates with higher histologic grades and poor prognosis. Our study identifies USP43 to be an H2BK120 deubiquitinase and a potential tumor suppressor and reveals a reciprocally inhibitory loop between USP43 and EGFR/PI3K/AKT, whose imbalance drives breast carcinogenesis.

Class I Histone Deacetylase Inhibition by Tianeptinaline Modulates Neuroplasticity and Enhances Memory.

Through epigenetic and other regulatory functions, the histone deacetylase (HDAC) family of enzymes has emerged as a promising therapeutic target for central nervous system and other disorders. Here we report on the synthesis and functional characterization of new HDAC inhibitors based structurally on tianeptine, a drug used primarily to treat major depressive disorder (MDD) that has a poorly understood mechanism of action. Since the chemical structure of tianeptine resembles certain HDAC inhibitors, we profiled the in vitro HDAC inhibitory activity of tianeptine and demonstrated its ability to inhibit the lysine deacetylase activity of a subset of class I HDACs. Consistent with a model of active site Zn2+ chelation by the carboxylic acid present in tianeptine, newly synthesized analogues containing either a hydroxamic acid or ortho-aminoanilide exhibited increased potency and selectivity among the HDAC family. This in vitro potency translated to improved efficacy in a panel of high-content imaging assays designed to assess HDAC target engagement and functional effects on critical pathways involved in neuroplasticity in both primary mouse neurons and, for the first time, human neurons differentiated from pluripotent stem cells. Most notably, tianeptinaline, a class I HDAC-selective analogue of tianeptine, but not tianeptine itself, increased histone acetylation, and enhanced CREB-mediated transcription and the expression of Arc (activity-regulated cytoskeleton-associated protein). Systemic in vivo administration of tianeptinaline to mice confirmed its brain penetration and was found to enhance contextual fear conditioning, a behavioral test of hippocampal-dependent memory. Tianeptinaline and its derivatives provide new pharmacological tools to dissect chromatin-mediated neuroplasticity underlying memory and other epigenetically related processes implicated in health and disease.

Nardilysin controls intestinal tumorigenesis through HDAC1/p53-dependent transcriptional regulation.

Colon cancer is a complex disease affected by a combination of genetic and epigenetic factors. Here we demonstrate that nardilysin (N-arginine dibasic convertase; NRDC), a metalloendopeptidase of the M16 family, regulates intestinal tumorigenesis via its nuclear functions. NRDC is highly expressed in human colorectal cancers. Deletion of the Nrdc gene in ApcMin mice crucially suppressed intestinal tumor development. In ApcMin mice, epithelial cell-specific deletion of Nrdc recapitulated the tumor suppression observed in Nrdc-null mice. Moreover, epithelial cell-specific overexpression of Nrdc significantly enhanced tumor formation in ApcMin mice. Notably, epithelial NRDC controlled cell apoptosis in a gene dosage-dependent manner. In human colon cancer cells, nuclear NRDC directly associated with HDAC1, and controlled both acetylation and stabilization of p53, with alterations of p53 target apoptotic factors. These findings demonstrate that NRDC is critically involved in intestinal tumorigenesis through its epigenetic regulatory function, and targeting NRDC may lead to a novel prevention or therapeutic strategy against colon cancer.