Early rhombic lip Protogenin stem cells in a human-specific neurovascular niche initiate and maintain group 3 medulloblastoma.

We identify a population of Protogenin-positive (PRTG) MYC NESTIN stem cells in the four-week-old human embryonic hindbrain that subsequently localizes to the ventricular zone of the rhombic lip (RL). Oncogenic transformation of early Prtg rhombic lip stem cells initiates group 3 medulloblastoma (Gr3-MB)-like tumors. PRTG stem cells grow adjacent to a human-specific interposed vascular plexus in the RL, a phenotype that is recapitulated in Gr3-MB but not in other types of medulloblastoma.

Integrin-based adhesions promote cell-cell junction and cytoskeletal remodelling to drive embryonic wound healing.

Embryos repair wounds rapidly, with no inflammation or scarring. Embryonic wound healing is driven by the collective movement of the cells around the lesion. The cells adjacent to the wound polarize the cytoskeletal protein actin and the molecular motor non-muscle myosin II, which accumulate at the wound edge forming a supracellular cable around the wound.

A neurodevelopmental epigenetic programme mediated by SMARCD3-DAB1-Reelin signalling is hijacked to promote medulloblastoma metastasis.

How abnormal neurodevelopment relates to the tumour aggressiveness of medulloblastoma (MB), the most common type of embryonal tumour, remains elusive. Here we uncover a neurodevelopmental epigenomic programme that is hijacked to induce MB metastatic dissemination. Unsupervised analyses of integrated publicly available datasets with our newly generated data reveal that SMARCD3 (also known as BAF60C) regulates Disabled 1 (DAB1)-mediated Reelin signalling in Purkinje cell migration and MB metastasis by orchestrating cis-regulatory elements at the DAB1 locus.

PyJAMAS: open-source, multimodal segmentation and analysis of microscopy images.

Summary: Our increasing ability to resolve fine details using light microscopy is matched by an increasing need to quantify images in order to detect and measure phenotypes. Despite their central role in cell biology, many image analysis tools require a financial investment, are released as proprietary software, or are implemented in languages not friendly for beginners, and thus are used as black boxes. To overcome these limitations, we have developed PyJAMAS, an open-source tool for image processing and analysis written in Python.

The transcriptional landscape of Shh medulloblastoma.

Sonic hedgehog medulloblastoma encompasses a clinically and molecularly diverse group of cancers of the developing central nervous system. Here, we use unbiased sequencing of the transcriptome across a large cohort of 250 tumors to reveal differences among molecular subtypes of the disease, and demonstrate the previously unappreciated importance of non-coding RNA transcripts. We identify alterations within the cAMP dependent pathway (GNAS, PRKAR1A) which converge on GLI2 activity and show that 18% of tumors have a genetic event that directly targets the abundance and/or stability of MYCN.

Metabolic Regulation of the Epigenome Drives Lethal Infantile Ependymoma.

Posterior fossa A (PFA) ependymomas are lethal malignancies of the hindbrain in infants and toddlers. Lacking highly recurrent somatic mutations, PFA ependymomas are proposed to be epigenetically driven tumors for which model systems are lacking. Here we demonstrate that PFA ependymomas are maintained under hypoxia, associated with restricted availability of specific metabolites to diminish histone methylation, and increase histone demethylation and acetylation at histone 3 lysine 27 (H3K27).

Locoregional delivery of CAR T cells to the cerebrospinal fluid for treatment of metastatic medulloblastoma and ependymoma.

Recurrent medulloblastoma and ependymoma are universally lethal, with no approved targeted therapies and few candidates presently under clinical evaluation. Nearly all recurrent medulloblastomas and posterior fossa group A (PFA) ependymomas are located adjacent to and bathed by the cerebrospinal fluid, presenting an opportunity for locoregional therapy, bypassing the blood-brain barrier. We identify three cell-surface targets, EPHA2, HER2 and interleukin 13 receptor α2, expressed on medulloblastomas and ependymomas, but not expressed in the normal developing brain.

Diminished AHR Signaling Drives Human Acute Myeloid Leukemia Stem Cell Maintenance.

Eliminating leukemic stem cells (LSC) is a sought after therapeutic paradigm for the treatment of acute myeloid leukemia (AML). While repression of aryl hydrocarbon receptor (AHR) signaling has been shown to promote short-term maintenance of primitive AML cells in culture, no work to date has examined whether altered AHR signaling plays a pathologic role in human AML or whether it contributes at all to endogenous LSC function. Here, we show AHR signaling is repressed in human AML blasts and preferentially downregulated in LSC-enriched populations within leukemias.

Changing the path of least resistance, or access to endo-dig products via a sequence of three exo-trig transition states: electronic effects in homoallyic ring expansion cascades of alkenyl isonitriles.

Chemoselective addition of radicals to isonitriles can be harnessed for initiating reaction cascades designed to overcome the stereoelectronic restrictions on homoallylic ring expansion in alkyne reactions and to develop a new general route for the preparation of N-heteroaromatics. This method utilizes alkenes as synthetic equivalents of alkynes by coupling homoallylic ring expansion to yield the formal "6-endo" products with aromatization via stereoelectronically assisted C-C bond scission. Detailed computational analysis of the individual steps of the homoallylic expansion sequence maps effects of substituents and structural constraints on this multi-step potential energy surface.

Coupling Radical Homoallylic Expansions with C-C Fragmentations for the Synthesis of Heteroaromatics: Quinolines from Reactions of o-Alkenylarylisonitriles with Aryl, Alkyl, and Perfluoroalkyl Radicals.

Selective addition of radicals to isonitriles can be harnessed for initiating reaction cascades designed to overcome the stereoelectronic restrictions on homoallylic ring expansion in alkyne reactions and to develop a new general route for the preparation of N-heteroaromatics. This method utilizes alkenes as synthetic equivalents of alkynes by coupling homoallylic ring expansion to yield the formal "6-endo" products with aromatization via stereoelectronically assisted C-C bond scission. Computational analysis of the homoallyic expansion potential energy surface reveals that the indirect 5-exo/3-exo/retro-3-exo path is faster than the direct 6-endo-trig closure, revealing the general exo-preference for the cyclization processes.

Coupling cyclizations with fragmentations for the preparation of heteroaromatics: quinolines from o-alkenyl arylisocyanides and boronic acids.

Stereoelectronic restrictions on homoallylic ring expansion in alkyne cascades can be overcome by using alkenes as synthetic equivalents of alkynes in reaction cascades that are terminated by C-C bond fragmentation. Implementation of this approach using Mn(iii)-mediated reaction of o-alkenyl isocyanides and boronic acids leads to efficient synthesis of substituted quinolines.

Notch-dependent regulation of the ischemic vasodilatory response--brief report.

Objective: We have recently described that Notch activates nitric oxide (NO) signaling in the embryonic endocardium. Both Notch signaling and NO signaling have been shown to be important during adult arteriogenesis. Notch has been shown to be required for remodeling of the collateral vessels, whereas NO is required for the initial vasodilatory response to ischemia.

Differentiation of vascular smooth muscle cells from local precursors during embryonic and adult arteriogenesis requires Notch signaling.

Vascular smooth muscle cells (VSMC) have been suggested to arise from various developmental sources during embryogenesis, depending on the vascular bed. However, evidence also points to a common subpopulation of vascular progenitor cells predisposed to VSMC fate in the embryo. In the present study, we use binary transgenic reporter mice to identify a Tie1(+)CD31(dim)vascular endothelial (VE)-cadherin(-)CD45(-) precursor that gives rise to VSMC in vivo in all vascular beds examined.