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Publications (3)32.08 Total impact

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    ABSTRACT: Class 3 semaphorins were initially described as axonal growth cone guidance molecules that signal through plexin and neuropilin coreceptors, and since have been established to be regulators of vascular development. Semaphorin 3e (Sema3e) was previously shown to repel endothelial cells and is the only class 3 semaphorin known to be capable of signaling via a plexin receptor without a neuropilin coreceptor. Sema3e signals through plexin D1 (Plxnd1) to regulate vascular patterning by modulating the cytoskeleton and focal adhesion structures. Recently, we have shown that semaphorin 3d (Sema3d) mediates endothelial cell repulsion and pulmonary vein patterning during embryogenesis. Here we show that Sema3d and Sema3e similarly affect human umbilical vein endothelial cells (HUVECs) but through distinct molecular signaling pathways. Time-lapse imaging studies show that both Sema3d and Sema3e can inhibit cell motility and migration, and tube formation assays indicate that both can impede tubulogenesis. Endothelial cells incubated with either Sema3d or Sema3e demonstrate a loss of actin stress fibers and focal adhesions. However, the addition of neuropilin 1 (Nrp1) blocking antibody or siRNA knockdown of Nrp1 inhibits Sema3d-mediated but not Sema3e-mediated cytoskeletal reorganization, and siRNA knockdown of Nrp1 abrogates Sema3d but not Sema3e-mediated inhibition of tubulogenesis. On the other hand, endothelial cells deficient in Plxnd1 are resistant to endothelial repulsion mediated by Sema3e, but not Sema3d. Unlike Sema3e, Sema3d incubation results in phosphorylation of Akt in HUVECs, and inhibition of the Phosphoinositide 3-kinase (PI3K)/Akt pathway blocks the endothelial guidance and cytoskeletal reorganization functions of Sema3d but not Sema3e.
    Journal of Biological Chemistry 05/2014; · 4.65 Impact Factor
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    ABSTRACT: Craniofacial development is characterized by reciprocal interactions between neural crest cells and neighboring cell populations of ectodermal, endodermal and mesodermal origin. Various genetic pathways play critical roles in coordinating the development of cranial structures by modulating the growth, survival and differentiation of neural crest cells. However, the regulation of these pathways, particularly at the epigenomic level, remains poorly understood. Using murine genetics, we show that neural crest cells exhibit a requirement for the class I histone deacetylase Hdac3 during craniofacial development. Mice in which Hdac3 has been conditionally deleted in neural crest demonstrate fully penetrant craniofacial abnormalities, including microcephaly, cleft secondary palate and dental hypoplasia. Consistent with these abnormalities, we observe dysregulation of cell cycle genes and increased apoptosis in neural crest structures in mutant embryos. Known regulators of cell cycle progression and apoptosis in neural crest, including Msx1, Msx2 and Bmp4, are upregulated in Hdac3-deficient cranial mesenchyme. These results suggest that Hdac3 serves as a critical regulator of craniofacial morphogenesis, in part by repressing core apoptotic pathways in cranial neural crest cells.
    Developmental Biology 03/2013; · 3.87 Impact Factor
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    ABSTRACT: Transcription factor-based cellular reprogramming has opened the way to converting somatic cells to a pluripotent state, but has faced limitations resulting from the requirement for transcription factors and the relative inefficiency of the process. We show here that expression of the miR302/367 cluster rapidly and efficiently reprograms mouse and human somatic cells to an iPSC state without a requirement for exogenous transcription factors. This miRNA-based reprogramming approach is two orders of magnitude more efficient than standard Oct4/Sox2/Klf4/Myc-mediated methods. Mouse and human miR302/367 iPSCs display similar characteristics to Oct4/Sox2/Klf4/Myc-iPSCs, including pluripotency marker expression, teratoma formation, and, for mouse cells, chimera contribution and germline contribution. We found that miR367 expression is required for miR302/367-mediated reprogramming and activates Oct4 gene expression, and that suppression of Hdac2 is also required. Thus, our data show that miRNA and Hdac-mediated pathways can cooperate in a powerful way to reprogram somatic cells to pluripotency.
    Cell stem cell 04/2011; 8(4):376-88. · 23.56 Impact Factor