Protein kinase Msk1 physically and functionally interacts with the KMT2A/MLL1 methyltransferase complex and contributes to the regulation of multiple target genes

KMT2A facilitates the epithelial-to-mesenchymal transition and the progression of ovarian cancer

Epithelial-mesenchymal transition (EMT) plays critical roles in cancer progression and metastasis. Thus, the exploration of the molecular mechanism regulating EMT would provide potential opportunities for the therapy of metastatic ovarian cancer (OC). Herein, we investigated the putative role of KMT2A in modulating EMT and metastasis in OC. The expression of KMT2A in OC was detected by Western blot and immunohistochemistry and its relationship with clinicopathological factors was analyzed. The effect of KMT2A on the biological behavior of OC cells was examined. Moreover, the expressions of EMT-associated proteins were detected in vivo and vitro by Western blot, immunofluorescence, and immunohistochemistry. KMT2A was highly expressed in OC cell lines and tissues and was positively correlated with advanced International Federation of Gynecology and Obstetrics (FIGO) stage, pathological grade, and metastasis. KMT2A overexpression was correlated with poor prognosis. Suppression of KMT2A inhibited OC cells proliferation, migration, and invasion and induced their apoptosis in vitro and vivo. In contrast, the ectopic expression of KMT2A had the opposite effects. Furthermore, KMT2A knockdown inhibited TGF-β-induced EMT in OC and reduced the phosphorylation levels of Smad2. Taken together, these observations demonstrate that KMT2A could promote the malignant behavior of OC by activating TGF-β/Smad signaling pathway and may be a potential prognostic biomarker and therapeutic target for OC.

Identifying regulators of aberrant stem cell and differentiation activity in colorectal cancer using a dual endogenous reporter system

Aberrant stem cell-like activity and impaired differentiation are central to the development of colorectal cancer (CRC). To identify functional mediators of these key cellular programs, we engineer a dual endogenous reporter system by genome-editing the SOX9 and KRT20 loci of human CRC cell lines to express fluorescent reporters, broadcasting aberrant stem cell-like and differentiation activity, respectively. By applying a CRISPR screen targeting 78 epigenetic regulators with 542 sgRNAs to this platform, we identify factors that contribute to stem cell-like activity and differentiation in CRC. Perturbation single cell RNA sequencing (Perturb-seq) of validated hits nominate SMARCB1 of the BAF complex (also known as SWI/SNF) as a negative regulator of differentiation across an array of neoplastic colon models. SMARCB1 is a dependency and required for in vivo growth of human CRC models. These studies highlight the utility of biologically designed endogenous reporter platforms to uncover regulators with therapeutic potential.

Utilizing a dual endogenous reporter system to identify functional regulators of aberrant stem cell and differentiation activity in colorectal cancer

Aberrant stem cell-like activity and impaired differentiation are central to the development of colorectal cancer (CRC). To identify functional mediators that regulate these key cellular programs in CRC, we developed an endogenous reporter system by genome-editing human CRC cell lines with knock-in fluorescent reporters at the SOX9 and KRT20 locus to report aberrant stem cell-like activity and differentiation, respectively, and then performed pooled genetic perturbation screens. Constructing a dual reporter system that simultaneously monitored aberrant stem cell-like and differentiation activity in the same CRC cell line improved our signal to noise discrimination. Using a focused-library CRISPR screen targeting 78 epigenetic regulators with 542 sgRNAs, we identified factors that contribute to stem cell-like activity and differentiation in CRC. Perturbation single cell RNA sequencing (Perturb-seq) of validated hits nominated SMARCB1 of the BAF complex (also known as SWI/SNF) as a negative regulator of differentiation across an array of neoplastic colon models. SMARCB1 is a dependency in CRC and required for in vivo growth of human CRC models. These studies highlight the utility of a biologically designed endogenous reporter system to uncover novel therapeutic targets for drug development.

Mitogen- and stress-activated protein kinase (MSK1/2) regulated gene expression in normal and disease states

The mitogen- and stress-activated protein kinases (MSK) are epigenetic modifiers that regulate gene expression in normal and disease cell states. MSK1 and 2 are involved in a chain of signal transduction events bringing signals from the external environment of a cell to specific sites in the genome. MSK1/2 phosphorylate histone H3 at multiple sites, resulting in chromatin remodeling at regulatory elements of target genes and the induction of gene expression. Several transcription factors (RELA of NF-κB and CREB) are also phosphorylated by MSK1/2 and contribute to induction of gene expression. In response to signal transduction pathways, MSK1/2 can stimulate genes involved in cell proliferation, inflammation, innate immunity, neuronal function, and neoplastic transformation. Abrogation of the MSK-involved signaling pathway is among the mechanisms by which pathogenic bacteria subdue the host's innate immunity. Depending on the signal transduction pathways in play and the MSK-targeted genes, MSK may promote or hinder metastasis. Thus, depending on the type of cancer and genes involved, MSK overexpression may be a good or poor prognostic factor. In this review, we focus on mechanisms by which MSK1/2 regulate gene expression, and recent studies on their roles in normal and diseased cells.

Anti-leukemic principle(s) from Momordica charantia seeds induce differentiation of HL-60 cells through ERK/MAPK signalling pathway

Myeloid leukemia is one of the major causes of deaths among elderly with very poor prognosis. Due to the adverse effects of existing chemotherapeutic agents, plant-derived components are being screened for their anti-leukemic potential. Momordica charantia (bitter gourd) possesses a variety of therapeutic activities. We have earlier demonstrated anti-leukemic activity of acetone extract of M. charantia seeds. The present study reports purification of differentiation inducing principle(s) from further fractionated seed extract (hexane fraction of the acetone extract, Mc2-Ac-hex) using HL-60 cells. Out of the 5 peak fractions (P1-P5) obtained from normal phase HPLC of the Mc2-Ac-hex, only peak fraction 3 (P3) induced differentiation of HL-60 cells as evident from an increase in NBT-positive cells and increased expression of cell surface marker CD11b. The P3 differentiated the HL-60 cells to granulocytic lineage, established by increased CD15 (granulocytic cell surface marker) expression in the treated cells. Further, possible molecular mechanism and the signalling pathway involved in the differentiation of HL-60 cells were also investigated. Use of specific signalling pathway inhibitors in the differentiation study, and proteome array analysis of the treated cells collectively revealed the involvement the of ERK/MAPK mediated pathway. Partial characterization of the P3 by GC-MS analysis revealed the presence of dibutyl phthalate, and derivatives of 2,5-dihydrofuran to be the highest among the 5 identified compounds. This study thus demonstrated that purified differentiation-inducing principle(s) from M. charantia seed extract induce HL-60 cells to granulocytic lineage through ERK/MAPK signalling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-022-00547-x.

Histone Modifications and Non-Coding RNAs: Mutual Epigenetic Regulation and Role in Pathogenesis

In the last few years, more and more scientists have suggested and confirmed that epigenetic regulators are tightly connected and form a comprehensive network of regulatory pathways and feedback loops. This is particularly interesting for a better understanding of processes that occur in the development and progression of various diseases. Appearing on the preclinical stages of diseases, epigenetic aberrations may be prominent biomarkers. Being dynamic and reversible, epigenetic modifications could become targets for a novel option for therapy. Therefore, in this review, we are focusing on histone modifications and ncRNAs, their mutual regulation, role in cellular processes and potential clinical application.

Compressive stress-mediated p38 activation required for ERα + phenotype in breast cancer

Breast cancer is now globally the most frequent cancer and leading cause of women's death. Two thirds of breast cancers express the luminal estrogen receptor-positive (ERα + ) phenotype that is initially responsive to antihormonal therapies, but drug resistance emerges. A major barrier to the understanding of the ERα-pathway biology and therapeutic discoveries is the restricted repertoire of luminal ERα + breast cancer models. The ERα + phenotype is not stable in cultured cells for reasons not fully understood. We examine 400 patient-derived breast epithelial and breast cancer explant cultures (PDECs) grown in various three-dimensional matrix scaffolds, finding that ERα is primarily regulated by the matrix stiffness. Matrix stiffness upregulates the ERα signaling via stress-mediated p38 activation and H3K27me3-mediated epigenetic regulation. The finding that the matrix stiffness is a central cue to the ERα phenotype reveals a mechanobiological component in breast tissue hormonal signaling and enables the development of novel therapeutic interventions. Subject terms: ER-positive (ER + ), breast cancer, ex vivo model, preclinical model, PDEC, stiffness, p38 SAPK.

The Glucocorticoid Receptor Polymorphism Landscape in Patients With Diamond Blackfan Anemia Reveals an Association Between Two Clinically Relevant Single Nucleotide Polymorphisms and Time to Diagnosis

NR3C1, the gene encoding the glucocorticoid receptor, is polymorphic presenting numerous single nucleotide polymorphisms (SNPs) some of which are emerging as leading cause in the variability of manifestation and/or response to glucocorticoids in human diseases. Since 60–80% of patients with Diamond Blackfan anemia (DBA), an inherited pure red cell aplasia induced by mutations in ribosomal protein genes became transfusion independent upon treatment with glucocorticoids, we investigated whether clinically relevant NR3C1 SNPs are associated with disease manifestation in DBA. The eight SNPs rs10482605, rs10482616, rs7701443, rs6189/rs6190, rs860457, rs6198, rs6196, and rs33388/rs33389 were investigated in a cohort of 91 European DBA patients. Results were compared with those observed in healthy volunteers (n=37) or present in public genome databases of Italian and European populations. Although, cases vs. control analyses suggest that the frequency of some of the minor alleles is significantly altered in DBA patients with respect to healthy controls or to the Italian or other European registries, lack of consistency among the associations across different sets suggests that overall the frequency of these SNPs in DBA is not different from that of the general population. Demographic data (47 females and 31 males) and driver mutations (44 S and 29 L genes and eight no-known mutation) are known for 81 patients while glucocorticoid response is known, respectively, for 81 (36 responsive and 45 non-responsive) and age of disease onsets for 79 (55 before and 24 after 4months of age) patients. Neither gender nor leading mutations were associated with the minor alleles or with disease manifestation. In addition, none of the SNPs met the threshold in the response vs. non-responsive groups. However, two SNPs (rs6196 and rs860457) were enriched in patients manifesting the disease before 4months of age. Although the exact biomechanistical consequences of these SNPs are unknown, the fact that their configuration is consistent with that of regulatory regions suggests that they regulate changes in glucocorticoid response during ontogeny. This hypothesis was supported by phosphoproteomic profiling of erythroid cells expanded ex vivo indicating that glucocorticoids activate a ribosomal signature in cells from cord blood but not in those from adult blood, possibly providing a compensatory mechanism to the driving mutations observed in DBA before birth.

Genome activation in equine in vitro-produced embryos

Embryonic genome activation is a critical event in embryo development, in which the transcriptional program of the embryo is initiated. The timing and regulation of this process are species-specific. In vitro embryo production is becoming an important clinical and research tool in the horse; however, very little is known about genome activation in this species. The objective of this work was to identify the timing of genome activation, and the transcriptional networks involved, in in vitro-produced horse embryos. RNA-Seq was performed on oocytes and embryos at eight stages of development (MII, zygote, 2-cell, 4-cell, 8-cell, 16-cell, morula, blastocyst; n = 6 per stage, 2 from each of 3 mares). Transcription of seven genes was initiated at the 2-cell stage. The first substantial increase in gene expression occurred at the 4-cell stage (minor activation), followed by massive gene upregulation and downregulation at the 8-cell stage (major activation). An increase in intronic nucleotides, indicative of transcription initiation, was also observed at the 4-cell stage. Co-expression network analyses identified groups of genes that appeared to be regulated by common mechanisms. Investigation of hub genes and binding motifs enriched in the promoters of co-expressed genes implicated several transcription factors. This work represents, to the best of our knowledge, the first genomic evaluation of embryonic genome activation in horse embryos.

Programmable human histone phosphorylation and gene activation using a CRISPR/Cas9-based chromatin kinase

Histone phosphorylation is a ubiquitous post-translational modification that allows eukaryotic cells to rapidly respond to environmental stimuli. Despite correlative evidence linking histone phosphorylation to changes in gene expression, establishing the causal role of this key epigenomic modification at diverse loci within native chromatin has been hampered by a lack of technologies enabling robust, locus-specific deposition of endogenous histone phosphorylation. To address this technological gap, here we build a programmable chromatin kinase, called dCas9-dMSK1, by directly fusing nuclease-null CRISPR/Cas9 to a hyperactive, truncated variant of the human MSK1 histone kinase. Targeting dCas9-dMSK1 to human promoters results in increased target histone phosphorylation and gene activation and demonstrates that hyperphosphorylation of histone H3 serine 28 (H3S28ph) in particular plays a causal role in the transactivation of human promoters. In addition, we uncover mediators of resistance to the BRAF V600E inhibitor PLX-4720 in human melanoma cells using genome-scale screening with dCas9-dMSK1. Collectively, our findings enable a facile way to reshape human chromatin using CRISPR/Cas9-based epigenome editing and further define the causal link between histone phosphorylation and human gene activation.

Histone phosphorylation is a ubiquitous post-translational modification. Here the authors present a programmable chromatin kinase, dCas9-dMSK1, that enables controlled histone phosphorylation and specific gene activation.

Oxycodone self-administration activates the mitogen-activated protein kinase/ mitogen- and stress-activated protein kinase (MAPK-MSK) signaling pathway in the rat dorsal striatum

To identify signaling pathways activated by oxycodone self-administration (SA), Sprague–Dawley rats self-administered oxycodone for 20 days using short—(ShA, 3 h) and long-access (LgA, 9 h) paradigms. Animals were euthanized 2 h after SA cessation and dorsal striata were used in post-mortem molecular analyses. LgA rats escalated their oxycodone intake and separated into lower (LgA-L) or higher (LgA-H) oxycodone takers. LgA-H rats showed increased striatal protein phosphorylation of ERK1/2 and MSK1/2. Histone H3, phosphorylated at serine 10 and acetylated at lysine 14 (H3S10pK14Ac), a MSK1/2 target, showed increased abundance only in LgA-H rats. RT-qPCR analyses revealed increased AMPA receptor subunits, GluA2 and GluA3 mRNAs, in the LgA-H rats. GluA3, but not GluA2, mRNA expression correlated positively with changes in pMSK1/2 and H3S10pK14Ac. These findings suggest that escalated oxycodone SA results in MSK1/2-dependent histone phosphorylation and increases in striatal gene expression. These observations offer potential avenues for interventions against oxycodone addiction.

Rebelled epigenome: histone H3S10 phosphorylation and H3S10 kinases in cancer biology and therapy

Background

With the discovery that more than half of human cancers harbor mutations in chromatin proteins, deregulation of epigenetic mechanisms has been recognized a hallmark of malignant transformation. Post-translational modifications (PTMs) of histone proteins, as main components of epigenetic regulatory machinery, are also broadly accepted as therapeutic target. Current “epigenetic” therapies target predominantly writers, erasers and readers of histone acetylation and (to a lesser extent) methylation, leaving other types of PTMs largely unexplored. One of them is the phosphorylation of serine 10 on histone H3 (H3S10ph).

Main body

H3S10ph is emerging as an important player in the initiation and propagation of cancer, as it facilitates cellular malignant transformation and participates in fundamental cellular functions. In normal cells this histone mark dictates the hierarchy of additional histone modifications involved in the formation of protein binding scaffolds, transcriptional regulation, blocking repressive epigenetic information and shielding gene regions from heterochromatin spreading. During cell division, this mark is essential for chromosome condensation and segregation. It is also involved in the function of specific DNA–RNA hybrids, called R-loops, which modulate transcription and facilitate chromosomal instability. Increase in H3S10ph is observed in numerous cancer types and its abundance has been associated with inferior prognosis. Many H3S10-kinases, including MSK1/2, PIM1, CDK8 and AURORA kinases, have been long considered targets in cancer therapy. However, since these proteins also participate in other critical processes, including signal transduction, apoptotic signaling, metabolic fitness and transcription, their chromatin functions are often neglected.

Conclusions

H3S10ph and enzymes responsible for deposition of this histone modification are important for chromatin activity and oncogenesis. Epigenetic-drugs targeting this axis of modifications, potentially in combination with conventional or targeted therapy, provide a promising angle in search for knowledge-driven therapeutic strategies in oncology.

How HP1 Post-Translational Modifications Regulate Heterochromatin Formation and Maintenance

Heterochromatin Protein 1 (HP1) is a highly conserved protein that has been used as a classic marker for heterochromatin. HP1 binds to di- and tri-methylated histone H3K9 and regulates heterochromatin formation, functions and structure. Besides the well-established phosphorylation of histone H3 Ser10 that has been shown to modulate HP1 binding to chromatin, several studies have recently highlighted the importance of HP1 post-translational modifications and additional epigenetic features for the modulation of HP1-chromatin binding ability and heterochromatin formation. In this review, we summarize the recent literature of HP1 post-translational modifications that have contributed to understand how heterochromatin is formed, regulated and maintained.

KMT2A regulates cervical cancer cell growth through targeting VDAC1

Cervical cancer is an aggressive cutaneous malignancy, illuminating the molecular mechanisms of tumorigenesis and discovering novel therapeutic targets are urgently needed. KMT2A is a transcriptional co-activator regulating gene expression during early development and hematopoiesis, but the role of KMT2A in cervical cancer remains unknown. Here, we demonstrated that KMT2A regulated cervical cancer growth via targeting VADC1. Knockdown of KMT2A significantly suppressed cell proliferation and migration and induced apoptosis in cervical cancer cells, accompanying with activation of PARP/caspase pathway and inhibition of VADC1. Overexpression of VDAC1 reversed the KMT2A knockdown-mediated regulation of cell proliferation, migration and apoptosis. The in vivo results from a cervical cancer xenograft mouse model also validated that KMT2A knockdown suppressed tumor growth by inhibiting VDAC1, whereas KMT2A overexpression promoted cervical cancer growth. Moreover, analyses of Biewenga cervix database and clinical samples showed that both KMT2A and VDAC1 were upregulated in cervix squamous cell carcinoma compared with cervix uteri tissues, and their expression was negatively correlated with the differentiation grade of cervical cancer. Our results therefore indicated that the KMT2A/VDAC1 signaling axis may be a potential new mechanism of cervical carcinogenesis.

Drosophila P75 safeguards oogenesis by preventing H3K9me2 spreading

Serving as a host factor for human immunodeficiency virus (HIV) integration, LEDGF/p75 has been under extensive study as a potential target for therapy. However, as a highly conserved protein, its physiological function remains to be thoroughly elucidated. Here, we characterize the molecular function of dP75, the Drosophila homolog of LEDGF/p75, during oogenesis. dP75 binds to transcriptionally active chromatin with its PWWP domain. The C-terminus integrase-binding domain-containing region of dP75 physically interacts with the histone kinase Jil-1 and stabilizes it in vivo. Together with Jil-1, dP75 prevents the spreading of the heterochromatin mark-H3K9me2-onto genes required for oogenesis and piRNA production. Without dP75, ectopical silencing of these genes disrupts oogenesis, activates transposons, and causes animal sterility. We propose that dP75, the homolog of an HIV host factor in Drosophila, partners with and stabilizes Jil-1 to ensure gene expression during oogenesis by preventing ectopic heterochromatin spreading.

Novel Insights into MSK1 Phosphorylation by MRKβ in Intracerebral Hemorrhage-Induced Neuronal Apoptosis

Neuronal apoptosis is regarded as one of the most important pathophysiological changes of intracerebral hemorrhagic (ICH) stroke—a major public health problem that leads to high mortality rates and functional dependency. Mitogen-and stress-activated kinase (MSK) 1 is implicated in various biological functions in different cell types, including proliferation, tumorigenesis and responses to stress. Our previous study showed that MSK1 phosphorylation (p-MSK1) is related to the regulation of LPS-induced astrocytic inflammation, and possibly acts as a negative regulator of inflammation. In this study, we identified a specific interaction between MSK1 and MRKβ (MLK-related kinase)—a member of the MAPK pathway—during neuronal apoptosis. In an ICH rat model, western blotting and immunohistochemical analysis revealed that both MRKβ and phosphorylation of MSK1 (p-MSK1 Ser376) were significantly upregulated in cells surrounding the hematoma. Triple-immunofluorescent labeling demonstrated the co-localization of MRKβ and p-MSK1 in neurons, but not astrocytes. Furthermore, MRKβ was partially transported into the nucleus, and interacted with p-MSK1 in hemin-treated neurons. Immunoprecipitation showed that MRKβ and p-MSK1 exhibited an enhanced interaction during the pathophysiology process. Utilizing small interfering RNAs to knockdown MRKβ or MSK1, we verified that MSK1 Ser376 is a phosphorylation site targeted by MRKβ. We also observed that the phosphorylation of NF-κB p65 at Ser276 was mediated by the MRKβ-p-MSK1 complex. Furthermore, it was found that the neuronal apoptosis marker, active caspase-3, was co-localized with MRKβ and p-MSK1. In addition, flow cytometry analysis revealed that knockdown of MRKβ or MSK1 specifically resulted in increased neuronal apoptosis, which suggested that the MRKβ-p-MSK1 complex might exert a neuroprotective function against ICH-induced neuronal apoptosis. Taken together, our data suggest that MRKβ translocated into the nucleus and phosphorylated MSK1 to protect neurons via phosphorylation of p65—a subunit of nuclear factor κB.

High expression of mitogen-activated and stress-activated protein kinase 1 indicates poor prognosis in patients with glioma

Mitogen-activated and stress-activated protein kinase 1 (MSK1), which belongs to the subfamily of MAPK-activated protein kinase, plays an important role in cell proliferation and neoplastic transformation. It has been recently reported that MSK1 overexpression was closely related to the progression of some tumors such as colorectal cancer. However, the clinical significance of MSK1 in glioma has not been addressed. To investigate the potential role of MSK1 in glioma, we first examined the expression pattern of MSK1 in glioma tissues and normal brain tissues using quantitative RT-PCR, and the results showing that MSK1 expression was significantly elevated in glioma tissues compared with normal brain tissues. The clinical relevance of MSK1 expression level was then analyzed, and we found that high expression of MSK1 was closely related to the larger tumor size and advanced WHO grade. Univariate and multivariate analyses revealed that glioma patients with higher expression of MSK1 had poorer overall survival, and MSK1 was identified as an independent unfavorable prognosis factor. In addition, the effects of MSK1 on glioma cells were tested through cellular experiments, and we demonstrated that MSK1 can promote proliferation and invasion capacities of tumor cells. In conclusion, patients with glioma with higher MSK1 expression were more predisposed to poorer clinical outcomes and unfavorable prognosis, indicating the potential role of MSK1 as a novel clinical biomarker and therapeutic target.

MSK1 functions as a transcriptional coactivator of p53 in the regulation of p21 gene expression

Mitogen- and stress-activated kinase 1 (MSK1) is a chromatin kinase that facilitates activator-dependent transcription by altering chromatin structure through histone H3 phosphorylation. The kinase activity of MSK1 is activated by intramolecular autophosphorylation, which is initially triggered by the activation of upstream mitogen-activated protein kinases (MAPKs), such as p38 and ERK1/2. MSK1 has been implicated in the expression of p21, a p53 target gene; however, the precise connection between MSK1 and p53 has not been clearly elucidated. Here, using in vitro and cell-based transcription assays, we show that MSK1 functions as a transcriptional coactivator of p53 in p21 expression, an action associated with MAPK-dependent phosphorylation of MSK1 and elevated kinase activity. Of special significance, we show that MSK1 directly interacts with p53 and is recruited to the p21 promoter, where it phosphorylates histone H3 in a p53-dependent manner. In addition, phosphomimetic mutant analysis demonstrated that negative charges in the hydrophobic motif are critical for serine 212 phosphorylation in the N-terminal kinase domain, which renders MSK1 competent for histone kinase activity. These studies suggest that MSK1 acts through a direct interaction with p53 to function as a transcriptional coactivator and that MSK1 activation by upstream MAPK signaling is important for efficient p21 gene expression.

RNA Sequencing and Pathway Analysis Identify Important Pathways Involved in Hypertrichosis and Intellectual Disability in Patients with Wiedemann-Steiner Syndrome

A growing number of histone modifiers are involved in human neurodevelopmental disorders, suggesting that proper regulation of chromatin state is essential for the development of the central nervous system. Among them, heterozygous de novo variants in KMT2A, a gene coding for histone methyltransferase, have been associated with Wiedemann-Steiner syndrome (WSS), a rare developmental disorder mainly characterized by intellectual disability (ID) and hypertrichosis. As KMT2A is known to regulate the expression of multiple target genes through methylation of lysine 4 of histone 3 (H3K4me), we sought to investigate the transcriptomic consequences of KMT2A variants involved in WSS. Using fibroblasts from four WSS patients harboring loss-of-function KMT2A variants, we performed RNA sequencing and identified a number of genes for which transcription was altered in KMT2A-mutated cells compared to the control ones. Strikingly, analysis of the pathways and biological functions significantly deregulated between patients with WSS and healthy individuals revealed a number of processes predicted to be altered that are relevant for hypertrichosis and intellectual disability, the cardinal signs of this disease.

KMT2A and KMT2B Mediate Memory Function by Affecting Distinct Genomic Regions

Kmt2a and Kmt2b are H3K4 methyltransferases of the Set1/Trithorax class. We have recently shown the importance of Kmt2b for learning and memory. Here, we report that Kmt2a is also important in memory formation. We compare the decrease in H3K4 methylation and de-regulation of gene expression in hippocampal neurons of mice with knockdown of either Kmt2a or Kmt2b. Kmt2a and Kmt2b control largely distinct genomic regions and different molecular pathways linked to neuronal plasticity. Finally, we show that the decrease in H3K4 methylation resulting from Kmt2a knockdown partially recapitulates the pattern previously reported in CK-p25 mice, a model for neurodegeneration and memory impairment. Our findings point to the distinct functions of even closely related histone-modifying enzymes and provide essential insight for the development of more efficient and specific epigenetic therapies against brain diseases.

Genetic variations on SETD5 underlying autistic conditions

The prevalence of autism spectrum disorders (ASD) and the number of identified ASD-related genes have increased in recent years. The SETD5 gene encodes a SET-containing-domain 5 protein, a likely reader enzyme. Genetic evidences suggest that SETD5 malfunction contributes to ASD phenotype, such as on intellectual disability (ID) and facial dysmorphism. In this review, we mapped the clinical phenotypes of individuals carrying mutations on the SETD5 gene that are associated with ASD and other chromatinopathies (mutation in epigenetic modifiers that leads to the development of neurodevelopmental disorders such as ASD). After a detailed systematic literature review and analysis of public disease-related databank, we found so far 42 individuals carrying mutations on the SETD5 gene, with 23.8% presenting autistic-like features. Furthermore, most of mutations occurred between positions 9,480,000-9,500,000 bp on chromosome 3 (3p25.3) at the SETD5 gene locus. In all males, mutations in SETD5 presented high penetrance, while in females the clinical phenotype seems more variable with two reported cases showing normal female carriers and not presenting ASD or any ID-like symptoms. At the molecular level, SETD5 interacts with proteins of PAF1C and N-CoR complexes, leading to a possible involvement with chromatin modification pathway, which plays important roles for brain development. Together, we propose that mutations on the SETD5 gene could lead to a new syndromic condition in males, which is linked to 3p25 syndrome, and can leads to ASD-related intellectual disability and facial dysmorphism. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 500-518, 2018.

Mitogen- and stress-activated protein kinase 1 is required for gonadotropin-releasing hormone-mediated activation of gonadotropin α-subunit expression

Pituitary gonadotropin hormones are regulated by gonadotropin-releasing hormone (GnRH) via MAPK signaling pathways that stimulate gene transcription of the common α-subunit (Cga) and the hormone-specific β-subunits of gonadotropin. We have reported previously that GnRH-induced activities at these genes include various histone modifications, but we did not examine histone phosphorylation. This modification adds a negative charge to residues of the histone tails that interact with the negatively charged DNA, is associated with closed chromatin during mitosis, but is increased at certain genes for transcriptional activation. Thus, the functions of this modification are unclear. We initially hypothesized that GnRH might induce phosphorylation of Ser-10 in histone 3 (H3S10p) as part of its regulation of gonadotropin gene expression, possibly involving cross-talk with H3K9 acetylation. We found that GnRH increases the levels of both modifications around the Cga gene transcriptional start site and that JNK inhibition dramatically reduces H3S10p levels. However, this modification had only a minor effect on Cga expression and no effect on H3K9ac. GnRH also increased H3S28p and H3K27ac levels and also those of activated mitogen- and stress-activated protein kinase 1 (MSK1). MSK1 inhibition dramatically reduced H3S28p levels in untreated and GnRH-treated cells and also affected H3K27ac levels. Although not affecting basal Cga expression, MSK1/2 inhibition repressed GnRH activation of Cga expression. Moreover, ChIP analysis revealed that GnRH-activated MSK1 targets the first nucleosome just downstream from the TSS. Given that the elongating RNA polymerase II (RNAPII) stalls at this well positioned nucleosome, GnRH-induced H3S28p, possibly in association with H3K27ac, would facilitate the progression of RNAPII.

MSK1 regulates transcriptional induction of Arc/Arg3.1 in response to neurotrophins

The immediate early gene activity‐regulated cytoskeletal protein (Arc)/Arg3.1 and the neurotrophin brain‐derived neurotrophic factor (BDNF) play important roles in synaptic plasticity and learning and memory in the mammalian brain. However, the mechanisms by which BDNF regulates the expression of Arc/Arg3.1 are unclear. In this study, we show that BDNF acts via the ERK1/2 pathway to activate the nuclear kinase mitogen‐ and stress‐activated protein kinase 1 (MSK1). MSK1 then induces Arc/Arg3.1 expression via the phosphorylation of histone H3 at the Arc/Arg3.1 promoter. MSK1 can also phosphorylate the transcription factor cyclic‐AMP response element‐binding protein (CREB) on Ser133. However, this is not required for BDNF‐induced Arc.Arg3.1 transcription as a Ser133Ala knockin mutation had no effect on Arc/Arg3.1 induction. In parallel, ERK1/2 directly activates Arc/Arg3.1 mRNA transcription via at least one serum response element on the promoter, which bind a complex of the Serum Response Factor (SRF) and a Ternary Complex Factor (TCF).