Schwann cell (SC) myelination in the peripheral nervous system is essential for motor function, and uncontrolled SC proliferation occurs in cancer. Here, we show that a dual role for Hippo effectors TAZ and YAP in SC proliferation and myelination through modulating G-protein expression and interacting with SOX10, respectively. Developmentally regulated mutagenesis indicates that TAZ/YAP are critical for SC proliferation and differentiation in a stage-dependent manner. Genome-wide occupancy mapping and transcriptome profiling reveal that nuclear TAZ/YAP promote SC proliferation by activating cell cycle regulators, while targeting critical differentiation regulators in cooperation with SOX10 for myelination. We further identify that TAZ targets and represses Gnas, encoding Gαs-protein, which opposes TAZ/YAP activities to decelerate proliferation. Gnas deletion expands SC precursor pools and blocks peripheral myelination. Thus, the Hippo/TAZ/YAP and Gαs-protein feedback circuit functions as a fulcrum balancing SC proliferation and differentiation, providing insights into molecular programming of SC lineage progression and homeostasis.

p53 is the most highly mutated tumor suppressor across multiple types of human cancers. The level and function of p53 are fine-tuned through multifaced mechanisms in which the protein-protein interaction between p53 and MDM2 is considered as a major circuit. Recent studies suggest therapeutic strategy attempts to restore p53 function by small molecule inhibitors targeting p53-MDM2 interaction can be a promising direction in treating cancers with wild-type or functional p53. Currently, clinical tests of the p53-MDM2 protein-protein interaction inhibitors (PPIs) are underway. However, it remains elusive about the biomarkers that may predict the therapeutic responses to those inhibitors. Here we report that RNA-binding protein LIN28B directly regulates p53 through binding to the 5'΄ untranslated region of p53 mRNA and blocks its translation by competing with a translation enhancer protein, ribosomal protein L26 (RPL26). This regulatory mechanism of LIN28B does not involve let-7 maturation or the canonical protein turnover pathway of p53. Furthermore, we show that inhibition of LIN28B unleashes the translational suppression of p53 through RPL26, and leads to enhanced sensitivities of cancer cells to inhibitors of p53-MDM2 interaction. Together, we demonstrate a competitive regulatory mechanism of p53 by LIN28B, which has important implications in developing biomarkers to the therapies aiming to reinstate p53 function.

Mutations in CHD7, encoding ATP-dependent chromodomain helicase DNA-binding protein 7, in CHARGE syndrome lead to multiple congenital anomalies, including craniofacial malformations, neurological dysfunction and growth delay. Mechanisms underlying the CNS phenotypes remain poorly understood. We found that Chd7 is a direct transcriptional target of oligodendrogenesis-promoting factors Olig2 and Smarca4/Brg1 and is required for proper onset of CNS myelination and remyelination. Genome-occupancy analyses in mice, coupled with transcriptome profiling, revealed that Chd7 interacted with Sox10 and targeted the enhancers of key myelinogenic genes. These analyses identified previously unknown Chd7 targets, including bone formation regulators Osterix (also known as Sp7) and Creb3l2, which are also critical for oligodendrocyte maturation. Thus, Chd7 coordinates with Sox10 to regulate the initiation of myelinogenesis and acts as a molecular nexus of regulatory networks that account for the development of a seemingly diverse array of lineages, including oligodendrocytes and osteoblasts, pointing to previously uncharacterized Chd7 functions in white matter pathogenesis in CHARGE syndrome.

Medulloblastoma, the most common malignant childhood brain tumor, exhibits distinct molecular subtypes and cellular origins. Genetic alterations driving medulloblastoma initiation and progression remain poorly understood. Herein, we identify GNAS, encoding the G protein Gαs, as a potent tumor suppressor gene that, when expressed at low levels, defines a subset of aggressive Sonic hedgehog (SHH)-driven human medulloblastomas. Ablation of the single Gnas gene in anatomically distinct progenitors in mice is sufficient to induce Shh-associated medulloblastomas, which recapitulate their human counterparts. Gαs is highly enriched at the primary cilium of granule neuron precursors and suppresses Shh signaling by regulating both the cAMP-dependent pathway and ciliary trafficking of Hedgehog pathway components. Elevation in levels of a Gαs effector, cAMP, effectively inhibits tumor cell proliferation and progression in Gnas-ablated mice. Thus, our gain- and loss-of-function studies identify a previously unrecognized tumor suppressor function for Gαs that can be found consistently across Shh-group medulloblastomas of disparate cellular and anatomical origins, highlighting G protein modulation as a potential therapeutic avenue.

Constitutive activation of Wnt/β-catenin inhibits oligodendrocyte myelination. Tcf7l2/Tcf4, a β-catenin transcriptional partner, is required for oligodendrocyte differentiation. How Tcf7l2 modifies β-catenin signalling and controls myelination remains elusive. Here we define a stage-specific Tcf7l2-regulated transcriptional circuitry in initiating and sustaining oligodendrocyte differentiation. Multistage genome occupancy analyses reveal that Tcf7l2 serially cooperates with distinct co-regulators to control oligodendrocyte lineage progression. At the differentiation onset, Tcf7l2 interacts with a transcriptional co-repressor Kaiso/Zbtb33 to block β-catenin signalling. During oligodendrocyte maturation, Tcf7l2 recruits and cooperates with Sox10 to promote myelination. In that context, Tcf7l2 directly activates cholesterol biosynthesis genes and cholesterol supplementation partially rescues oligodendrocyte differentiation defects in Tcf712 mutants. Together, we identify stage-specific co-regulators Kaiso and Sox10 that sequentially interact with Tcf7l2 to coordinate the switch at the transitions of differentiation initiation and maturation during oligodendrocyte development, and point to a previously unrecognized role of Tcf7l2 in control of cholesterol biosynthesis for CNS myelinogenesis.

Malignant gliomas exhibit extensive heterogeneity and poor prognosis. Here we identify mitotic Olig2-expressing cells as tumor-propagating cells in proneural gliomas, elimination of which blocks tumor initiation and progression. Intriguingly, deletion of Olig2 resulted in tumors that grow, albeit at a decelerated rate. Genome occupancy and expression profiling analyses reveal that Olig2 directly activates cell-proliferation machinery to promote tumorigenesis. Olig2 deletion causes a tumor phenotypic shift from an oligodendrocyte precursor-correlated proneural toward an astroglia-associated gene expression pattern, manifest in downregulation of platelet-derived growth factor receptor-α and reciprocal upregulation of epidermal growth factor receptor (EGFR). Olig2 deletion further sensitizes glioma cells to EGFR inhibitors and extends the lifespan of animals. Thus, Olig2-orchestrated receptor signaling drives mitotic growth and regulates glioma phenotypic plasticity. Targeting Olig2 may circumvent resistance to EGFR-targeted drugs.

Orthodontic treatment can result in root resorption (RR). Traditional two-dimensional (2D) data exhibit magnification, deformation and positioning problems. Cone beam computed tomography (CBCT) contains more accurate three-dimensional (3D) information. This study identified and qualified the extent and location of root resorption using cone beam computed tomography (CBCT) after comprehensive orthodontic treatment.

Disruptive mutations in chromatin remodeler CHD8 cause autism spectrum disorders, exhibiting widespread white matter abnormalities; however, the underlying mechanisms remain elusive. We show that cell-type specific Chd8 deletion in oligodendrocyte progenitors, but not in neurons, results in myelination defects, revealing a cell-intrinsic dependence on CHD8 for oligodendrocyte lineage development, myelination and post-injury remyelination. CHD8 activates expression of BRG1-associated SWI/SNF complexes that in turn activate CHD7, thus initiating a successive chromatin remodeling cascade that orchestrates oligodendrocyte lineage progression. Genomic occupancy analyses reveal that CHD8 establishes an accessible chromatin landscape, and recruits MLL/KMT2 histone methyltransferase complexes distinctively around proximal promoters to promote oligodendrocyte differentiation. Inhibition of histone demethylase activity partially rescues myelination defects of CHD8-deficient mutants. Our data indicate that CHD8 exhibits a dual function through inducing a cascade of chromatin reprogramming and recruiting H3K4 histone methyltransferases to establish oligodendrocyte identity, suggesting potential strategies of therapeutic intervention for CHD8-associated white matter defects.

A lack of sufficient oligodendrocyte myelination contributes to remyelination failure in demyelinating disorders. miRNAs have been implicated in oligodendrogenesis; however, their functions in myelin regeneration remained elusive. Through developmentally regulated targeted mutagenesis, we demonstrate that miR-219 alleles are critical for CNS myelination and remyelination after injury. Further deletion of miR-338 exacerbates the miR-219 mutant hypomyelination phenotype. Conversely, miR-219 overexpression promotes precocious oligodendrocyte maturation and regeneration processes in transgenic mice. Integrated transcriptome profiling and biotin-affinity miRNA pull-down approaches reveal stage-specific miR-219 targets in oligodendrocytes and further uncover a novel network for miR-219 targeting of differentiation inhibitors including Lingo1 and Etv5. Inhibition of Lingo1 and Etv5 partially rescues differentiation defects of miR-219-deficient oligodendrocyte precursors. Furthermore, miR-219 mimics enhance myelin restoration following lysolecithin-induced demyelination as well as experimental autoimmune encephalomyelitis, principal animal models of multiple sclerosis. Together, our findings identify context-specific miRNA-regulated checkpoints that control myelinogenesis and a therapeutic role for miR-219 in CNS myelin repair.

The VEGF family comprises seven members that are designated VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, placental growth factor (PlGF), and VEGF-F. Of these factors, VEGF-D plays important roles for angiogenesis and lymphangiogenesis, and could promote tumor growth and lymphatic metastasis. In this study, we identified a zebrafish VEGF-D homolog that encodes a 272 amino acid protein including a PDGF (platelet-derived growth factor) domain characteristic to VEGF family. Expression profile demonstrated that the VEGF-D began expressed from 13 somite stage. Microinjecting zVEGF-D mRNA into zebrafish 1-cell stage embryos resulted in severe misguidance of intersegmental vessels (ISV) and abnormal connection between dorsal aorta and caudal vein. Microangiography indicated that these abnormal ISVs were not functional. Our studies therefore identified the first non-mammalian VEGF-D and established its in vivo role for vascular system development during vertebrate embryogenesis and provided an alternative animal model to further reveal functions of VEGF-D.

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive Schwann cell (SC)-lineage-derived sarcomas. Molecular events driving SC-to-MPNST transformation are incompletely understood. Here, we show that human MPNSTs exhibit elevated HIPPO-TAZ/YAP expression, and that TAZ/YAP hyperactivity in SCs caused by Lats1/2 loss potently induces high-grade nerve-associated tumors with full penetrance. Lats1/2 deficiency reprograms SCs to a cancerous, progenitor-like phenotype and promotes hyperproliferation. Conversely, disruption of TAZ/YAP activity alleviates tumor burden in Lats1/2-deficient mice and inhibits human MPNST cell proliferation. Moreover, genome-wide profiling reveals that TAZ/YAP-TEAD1 directly activates oncogenic programs, including platelet-derived growth factor receptor (PDGFR) signaling. Co-targeting TAZ/YAP and PDGFR pathways inhibits tumor growth. Thus, our findings establish a previously unrecognized convergence between Lats1/2-TAZ/YAP signaling and MPNST pathogenesis, revealing potential therapeutic targets in these untreatable tumors.

Long noncoding RNAs (lncRNAs) are emerging as important regulators of cellular functions, but their roles in oligodendrocyte myelination remain undefined. Through de novo transcriptome reconstruction, we establish dynamic expression profiles of lncRNAs at different stages of oligodendrocyte development and uncover a cohort of stage-specific oligodendrocyte-restricted lncRNAs, including a conserved chromatin-associated lncOL1. Co-expression network analyses further define the association of distinct oligodendrocyte-expressing lncRNA clusters with protein-coding genes and predict lncRNA functions in oligodendrocyte myelination. Overexpression of lncOL1 promotes precocious oligodendrocyte differentiation in the developing brain, whereas genetic inactivation of lncOL1 causes defects in CNS myelination and remyelination following injury. Functional analyses illustrate that lncOL1 interacts with Suz12, a component of polycomb repressive complex 2, to promote oligodendrocyte maturation, in part, through Suz12-mediated repression of a differentiation inhibitory network that maintains the precursor state. Together, our findings reveal a key lncRNA epigenetic circuitry through interaction with chromatin-modifying complexes in control of CNS myelination and myelin repair.

Due to unknown pathogenesis and unidentified drug target, no drug for the treatment of osteosarcoma (OS) has been launched to the market. Herein, thiazolidinone 1a was discovered as a hit compound by phenotypic screening with an in-house patrimonial collection of structural diversity. The following SAR (Structure-Activity Relationship) study affords the final water-soluble lead compound (R)-8i as a potential inhibitor for the proliferation of OS cells by the modulation of solubility of the compounds with remarkable cellular potency (IC50 = 21.9 nM for MNNG/HOS cells) and in vivo efficacy (52.9% inhibition OS growth in mice), as well as pharmacokinetic properties. (R)-8i also significantly suppresses OS cell migration in vitro and showed to be well-tolerated. Our preliminary investigation shows that the effects of (R)-8i are not dependent on p53 and myoferlin (MYOF). These results suggest that (R)-8i might be a potential drug candidate for OS treatment.