Single-Cell Transcriptome Analysis Defines Expression of Kabuki Syndrome-Associated KMT2D Targets and Interacting Partners.

Objectives. Kabuki syndrome (KS) is a rare genetic disorder characterized by developmental delay, retarded growth, and cardiac, gastrointestinal, neurocognitive, renal, craniofacial, dental, and skeletal defects. KS is caused by mutations in the genes encoding histone H3 lysine 4 methyltransferase (KMT2D) and histone H3 lysine 27 demethylase (KDM6A), which are core components of the complex of proteins associated with histone H3 lysine 4 methyltransferase SET1 (SET1/COMPASS). Using single-cell RNA data, we examined the expression profiles of Kmt2d and Kdm6a in the mouse dental pulp. In the incisor pulp, Kmt2d and Kdm6a colocalize with other genes of the SET1/COMPASS complex comprised of the WD-repeat protein 5 gene (Wdr5), the retinoblastoma-binding protein 5 gene (Rbbp5), absent, small, and homeotic 2-like protein-encoding gene (Ash2l), nuclear receptor cofactor 6 gene (Ncoa6), and Pax-interacting protein 1 gene (Ptip1). In addition, we found that Kmt2d and Kdm6a coexpress with the downstream target genes of the Wingless and Integrated (WNT) and sonic hedgehog signaling pathways in mesenchymal stem/stromal cells (MSCs) at different stages of osteogenic differentiation. Taken together, our results suggest an essential role of KMT2D and KDK6A in directing lineage-specific gene expression during differentiation of MSCs

Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis.

BACKGROUND: Gastrointestinal mucosal injury (mucositis), commonly affecting the oral cavity, is a clinically significant yet incompletely understood complication of cancer chemotherapy. Although antineoplastic cytotoxicity constitutes the primary injury trigger, the interaction of oral microbial commensals with mucosal tissues could modify the response. It is not clear, however, whether chemotherapy and its associated treatments affect oral microbial communities disrupting the homeostatic balance between resident microorganisms and the adjacent mucosa and if such alterations are associated with mucositis. To gain knowledge on the pathophysiology of oral mucositis, 49 subjects receiving 5-fluorouracil (5-FU) or doxorubicin-based chemotherapy were evaluated longitudinally during one cycle, assessing clinical outcomes, bacterial and fungal oral microbiome changes, and epithelial transcriptome responses. As a control for microbiome stability, 30 non-cancer subjects were longitudinally assessed. Through complementary in vitro assays, we also evaluated the antibacterial potential of 5-FU on oral microorganisms and the interaction of commensals with oral epithelial tissues. RESULTS: Oral mucositis severity was associated with 5-FU, increased salivary flow, and higher oral granulocyte counts. The oral bacteriome was disrupted during chemotherapy and while antibiotic and acid inhibitor intake contributed to these changes, bacteriome disruptions were also correlated with antineoplastics and independently and strongly associated with oral mucositis severity. Mucositis-associated bacteriome shifts included depletion of common health-associated commensals from the genera Streptococcus, Actinomyces, Gemella, Granulicatella, and Veillonella and enrichment of Gram-negative bacteria such as Fusobacterium nucleatum and Prevotella oris. Shifts could not be explained by a direct antibacterial effect of 5-FU, but rather resembled the inflammation-associated dysbiotic shifts seen in other oral conditions. Epithelial transcriptional responses during chemotherapy included upregulation of genes involved in innate immunity and apoptosis. Using a multilayer epithelial construct, we show mucositis-associated dysbiotic shifts may contribute to aggravate mucosal damage since the mucositis-depleted Streptococcus salivarius was tolerated as a commensal, while the mucositis-enriched F. nucleatum displayed pro-inflammatory and pro-apoptotic capacity. CONCLUSIONS: Altogether, our work reveals that chemotherapy-induced oral mucositis is associated with bacterial dysbiosis and demonstrates the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury. These findings suggest that control of oral bacterial dysbiosis could represent a novel preventive approach to ameliorate oral mucositis

Diversity and Complexity in Chromatin Recognition by TFII-I Transcription Factors in Pluripotent Embryonic Stem Cells and Embryonic Tissues

<div><p><em>GTF2I</em> and <em>GTF2IRD1</em> encode a family of closely related transcription factors TFII-I and BEN critical in embryonic development. Both genes are deleted in Williams-Beuren syndrome, a complex genetic disorder associated with neurocognitive, craniofacial, dental and skeletal abnormalities. Although genome-wide promoter analysis has revealed the existence of multiple TFII-I binding sites in embryonic stem cells (ESCs), there was no correlation between TFII-I occupancy and gene expression. Surprisingly, TFII-I recognizes the promoter sequences enriched for H3K4me3/K27me3 bivalent domain, an epigenetic signature of developmentally important genes. Moreover, we discovered significant differences in the association between TFII-I and BEN with the <em>cis</em>-regulatory elements in ESCs and embryonic craniofacial tissues. Our data indicate that in embryonic tissues BEN, but not the highly homologous TFII-I, is primarily recruited to target gene promoters. We propose a “feed-forward model” of gene regulation to explain the specificity of promoter recognition by TFII-I factors in eukaryotic cells.</p> </div

Single-cell transcriptomics defines Dot1L interacting partners and downstream target genes in the mouse molar dental pulp.

Although histone methyltransferases are implicated in many key developmental processes, the contribution of individual chromatin modifiers in dental tissues is not well understood. Using single-cell RNA sequencing, we examined the expression profiles of the disruptor of telomeric silencing 1-like

Chromatin isolation and ChIP-chip analysis.

<p>(A) The ChIP-chip strategy. Chromatin was isolated from mouse ESCs and the craniofacial region (CF) of E10.5 mouse embryos. Chromatin immunoprecipitation (ChIP) was performed with TFII-I and BEN-specific antibodies. CF region is marked in red with dashed lines. (B) The correlation between the genome-wide promoter binding using goat anti-BEN and mouse anti-HA antibodies to BEN (left) and rabbit and goat polyclonal antibodies to TFII-I (right). Spearman’s rank correlation coefficient (r) is calculated for each antibody pair. (C) The overall statistics of TFII-I and BEN target genes in ESCs and embryonic craniofacial tissues. (D) Distribution of the TFII-I and BEN-bound genomic sites with respect to the gene structure. The 2 kb region upstream of the transcription start site (TSS) is arbitrarily divided into two 1 kb segments (‘enhancer region’ and ‘proximal promoter’). 0.5 kb region downstream from TSS is split into exon and intron sequences. Bars represent the standard deviation calculated from four (TFII-I) or six (BEN) chip hybridizations, *p<0.1, **p<0.05, ***p<0.01.</p

Promoter recognition by the TFII-I family.

<p>TFII-I (in red) and BEN (in blue) possess distinct promoter recognition properties in ESCs and embryonic craniofacial tissues (ETs). First, the majority of ESC promoters occupied by TFII-I become vacant in ETs (a); second, a large number of ESC promoters recognized by BEN recruit both transcription factors to the same site in ETs (b); third, the ESC promoters occupied by TFII-I and BEN are still recognized by both transcription factors in ETs, predominantly in the same sequence, although some sites lost their binding completely (d); and fourth, the promoters active in ETs recruit more BEN than TFII-I (e). The black numbers on the right indicate percentage expected from the random distribution of TFII-I or BEN binding. The green numbers indicate the observed distribution significantly deviated from the random distribution (chi-squared test).</p

Colocalization of bivalent chromatin with TFII-I bound sites.

<p>TFII-I associates with the promoter regions of key developmental genes enriched for H3K4me3 and H3K27me3 marks.</p

TFII-I factors occupy the promoters of key developmental regulators in ESCs and embryonic craniofacial tissues (ETs).

<p>(A) TFII-I and BEN bind to the promoters of <i>Ednra, Edn1, Sox2, Sox3, Hoxa1</i> and <i>Gata3</i> implicated in neural crest and craniofacial development. (B) TFII-I occupies the promoters of <i>Emx1, Emx2, Zic1</i> and <i>Neurod4</i> involved in brain development. The notation and labeling are as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044443#pone-0044443-g002" target="_blank">Figure 2B</a>. (C) TFII-I and BEN occupy the promoter regions of the <i>HoxA</i> cluster (<i>Hoxa1, Hoxa7</i> and <i>Hoxa13</i>) in mouse ESCs and ETs. (D) TFII-I and BEN recognize the same <i>cis</i>-regulatory element in the promoters of <i>Dicer, Cdx2</i> and <i>Olfr480</i> in stem cells and embryonic tissues. (E) TFII-I binds to the promoters of <i>Twist1, Snail2, Ezh2 and Nsd1</i> (red lines) in ESCs, although BEN does not bind to these promoters (blue lines). siRNA-mediated knockdown of TFII-I down-regulates expression of <i>Twist</i>, <i>Snail1, Ezh2</i> and <i>Nsd1</i> in embryonic neural crest cells (JoMa1.3 line). Error bars represent the standard deviation calculated from three independent knockdown experiments.</p