Propranolol treatment of infantile hemangioma endothelial cells: A molecular analysis

Infantile hemangiomas (IHs) are non-malignant, largely cutaneous vascular tumors affecting approximately 5–10% of children to varying degrees. During the first year of life, these tumors are strongly proliferative, reaching an average size ranging from 2 to 20 cm. These lesions subsequently stabilize, undergo a spontaneous slow involution and are fully regressed by 5 to 10 years of age. Systemic treatment of infants with the non-selective β-adrenergic receptor blocker, propranolol, has demonstrated remarkable efficacy in reducing the size and appearance of IHs. However, the mechanism by which this occurs is largely unknown. In this study, we sought to understand the molecular mechanisms underlying the effectiveness of β blocker treatment in IHs. Our data reveal that propranolol treatment of IH endothelial cells, as well as a panel of normal primary endothelial cells, blocks endothelial cell proliferation, migration, and formation of the actin cytoskeleton coincident with alterations in vascular endothelial growth factor receptor-2 (VEGFR-2), p38 and cofilin signaling. Moreover, propranolol induces major alterations in the protein levels of key cyclins and cyclin-dependent kinase inhibitors, and modulates global gene expression patterns with a particular affect on genes involved in lipid/sterol metabolism, cell cycle regulation, angiogenesis and ubiquitination. Interestingly, the effects of propranolol were endothelial cell-type independent, affecting the properties of IH endothelial cells at similar levels to that observed in neonatal dermal microvascular and coronary artery endothelial cells. This data suggests that while propranolol markedly inhibits hemangioma and normal endothelial cell function, its lack of endothelial cell specificity hints that the efficacy of this drug in the treatment of IHs may be more complex than simply blockage of endothelial function as previously believed

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Mapping of DNA Replication Origins to Noncoding Genes of the X-Inactivation Center

In mammals, few DNA replication origins have been identified. Although there appears to be an association between origins and epigenetic regulation, their underlying link to monoallelic gene expression remains unclear. Here, we identify novel origins of DNA replication (ORIs) within the X-inactivation center (Xic). We analyze 86 kb of the Xic using an unbiased approach and find an unexpectedly large number of functional ORIs. Although there has been a tight correlation between ORIs and CpG islands, we find that ORIs are not restricted to CpG islands and there is no dependence on transcriptional activity. Interestingly, these ORIs colocalize to important genetic elements or genes involved in X-chromosome inactivation. One prominent ORI maps to the imprinting center and to a domain within Tsix known to be required for X-chromosome counting and choice. Location and/or activity of ORIs appear to be modulated by removal of specific Xic elements. These data provide a foundation for testing potential relationships between DNA replication and epigenetic regulation in future studies

CTCF mediates insulator function at the CFTR locus

Regulatory elements that lie outside the basal promoter of a gene may be revealed by local changes in chromatin structure and histone modifications. The promoter of the CFTR (cystic fibrosis transmembrane conductance regulator) gene is not responsible for its complex pattern of expression. To identify important regulatory elements for CFTR we have previously mapped DHS (DNase I-hypersensitive sites) across 400 kb spanning the locus. Of particular interest were two DHS that flank the CFTR gene, upstream at −20.9 kb with respect to the translational start site, and downstream at +15.6 kb. In the present study we show that these two DHS possess enhancer-blocking activity and bind proteins that are characteristic of known insulator elements. The DHS core at −20.9 kb binds CTCF (CCCTC-binding factor) both in vitro and in vivo; however, the +15.6 kb core appears to bind other factors. Histone-modification analysis across the CFTR locus highlights structural differences between the −20.9 kb and +15.6 kb DHS, further suggesting that these two insulator elements may operate by distinct mechanisms. We propose that these two DHS mark the boundaries of the CFTR gene functional unit and establish a chromatin domain within which the complex profile of CFTR expression is maintained

Novel Pancreatic Endocrine Maturation Pathways Identified by Genomic Profiling and Causal Reasoning

<div><p>We have used a previously unavailable model of pancreatic development, derived <em>in vitro</em> from human embryonic stem cells, to capture a time-course of gene, miRNA and histone modification levels in pancreatic endocrine cells. We investigated whether it is possible to better understand, and hence control, the biological pathways leading to pancreatic endocrine formation by analysing this information and combining it with the available scientific literature to generate models using a casual reasoning approach. We show that the embryonic stem cell differentiation protocol is highly reproducible in producing endocrine precursor cells and generates cells that recapitulate many aspects of human embryonic pancreas development, including maturation into functional endocrine cells when transplanted into recipient animals. The availability of whole genome gene and miRNA expression data from the early stages of human pancreatic development will be of great benefit to those in the fields of developmental biology and diabetes research. Our causal reasoning algorithm suggested the involvement of novel gene networks, such as NEUROG3/E2F1/KDM5B and SOCS3/STAT3/IL-6, in endocrine cell development We experimentally investigated the role of the top-ranked prediction by showing that addition of exogenous IL-6 could affect the expression of the endocrine progenitor genes NEUROG3 and NKX2.2.</p> </div

Induction of insulin expression is not accompanied with epigenetic changes.

<p>(A) Gene expression (blue) and H3K4me³ level (red) profiles for SOX17. The horizontal dashed line indicates the background H3K4me³ level. (B) H3K4me³ reads piled up over the SOX17 gene body at days 0, 2 and 11. The start and end points of SOX17 are indicated by dashed lines. (C&D) As for (A&B) but for Insulin.</p

Top 20 protein causal drivers of early pancreatic endoderm formation between day 8 and day 11.

<p>The number of correctly, incorrectly and ambiguously explained gene expression observations are given for each gene as well as the predicted direction of regulation (up meaning activation/down meaning inhibition). The notes for each gene indicate that in cases where the gene is already associated with beta cell function whether it is generally considered a positive or negative regulator of beta cell differentiation, proliferation (growth) or apoptosis. All hypotheses pass correctness and enrichment p-value thresholds of 10⁻⁵.</p

IL6, the top CRE prediction, has effects on expression of endocrine markers.

<p>(A) Treatment of pancreatic aggregates with IL-6 induces de novo gene expression of the pro-endocrine transcription factors NEUROG3 and NKX2.2, indicating commitment of pancreatic progenitor cells into the endocrine lineage. Noggin induction of these genes resulted in 8-fold increases (data not shown) (B) Gene expression in response to IL-6 was compared between whole aggregates (mixture of pancreatic progenitors and endocrine cells) and cultures of enriched endocrine cells (depleted of pancreatic progenitors). Induction of NKX2.2 expression was only seen in whole aggregates, consistent with the role of IL-6 in converting pancreatic progenitors into new endocrine cells. Enhanced expression of NEUROD1, IAPP, and SOMATOSTATIN seen in response to IL-6 in purified endocrine cells, suggesting IL-6 has additional roles in committed endocrine cells. No significant differences seen in INSULIN or GCG gene expression. Statistical testing using a standard t-test was performed.</p

Expression of cholesterol metabolizing genes shows a strong time dependence.

<p>(A) The cholesterol biosynthesis pathway from squalene-PP (top left) to cholesterol (top right) showing all enzymes and some intermediates. Enzymes whose gene expression patterns fall into the largest cluster seen in the heatmap of the expression levels for these enzymes (B) are colored purple, other enzymes are light blue. LIPA and SOAT1/2 interconvert cholesterol and cholesterol ester. The cholesterol sensitive miRNA-33a shows a similar expression pattern (C) to the main cluster.</p

Epigenetic changes can be used to identify novel regulatory miRNAs.

<p>(A–C) Gene expression (blue), miRNA expression (green) and H3K4me³ levels for CD47, ITGB1 and ANP32B and the miRNAs associated with them. In all 3 cases the miRNA is predicted to regulate the relevant gene and is also anti-correlated in level. In (A) H3K4me³ levels correlate closely with the gene expression, whilst in (B & C) there is no correlation, suggesting a stronger role for the miRNA regulation.</p