RESUMO
Progressive myoclonus epilepsy (PME) is a syndrome characterized by myoclonic seizures (lightning-like jerks), generalized convulsive seizures, and varying degrees of neurological decline, especially ataxia and dementia. Previously, we characterized three pedigrees of individuals with PME and ataxia, where either clinical features or linkage mapping excluded known PME loci. This report identifies a mutation in PRICKLE1 (also known as RILP for REST/NRSF interacting LIM domain protein) in all three of these pedigrees. The identified PRICKLE1 mutation blocks the PRICKLE1 and REST interaction in vitro and disrupts the normal function of PRICKLE1 in an in vivo zebrafish overexpression system. PRICKLE1 is expressed in brain regions implicated in epilepsy and ataxia in mice and humans, and, to our knowledge, is the first molecule in the noncanonical WNT signaling pathway to be directly implicated in human epilepsy.
Assuntos
Ataxia/genética , Homozigoto , Mutação , Epilepsias Mioclônicas Progressivas/genética , Proteínas Supressoras de Tumor/genética , Sequência de Aminoácidos , Cromossomos Humanos Par 12 , Consanguinidade , Genes Recessivos , Marcadores Genéticos , Haplótipos , Humanos , Proteínas com Domínio LIM , Masculino , Repetições de Microssatélites , Pessoa de Meia-Idade , Dados de Sequência Molecular , Linhagem , Mapeamento Físico do Cromossomo , SíndromeRESUMO
The planar cell polarity (PCP) pathway is a highly conserved signaling cascade that coordinates both epithelial and axonal morphogenic movements during development. Angiogenesis also involves the growth and migration of polarized cells, although the mechanisms underlying their intercellular communication are poorly understood. Here, using cell culture assays, we demonstrate that inhibition of PCP signaling disrupts endothelial cell growth, polarity, and migration, all of which can be rescued through downstream activation of this pathway by expression of either Daam-1, Diversin or Inversin. Silencing of either Dvl2 or Prickle suppressed endothelial cell proliferation. Moreover, loss of p53 rescues endothelial cell growth arrest but not the migration inhibition caused by PCP disruption. In addition, we show that the zebrafish Wnt5 mutant (pipetail (ppt)), which has impaired PCP signaling, displays vascular developmental defects. These findings reveal a potential role for PCP signaling in the coordinated assembly of endothelial cells into vascular structures and have important implications for vascular remodeling in development and disease.
Assuntos
Polaridade Celular , Neovascularização Fisiológica , Transdução de Sinais , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Vasos Sanguíneos/anormalidades , Vasos Sanguíneos/efeitos dos fármacos , Caveolina 1/metabolismo , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Polaridade Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cicloexanos/farmacologia , Proteínas Desgrenhadas , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Humanos , Camundongos , Modelos Animais , Mutação/genética , Neovascularização Fisiológica/efeitos dos fármacos , O-(Cloroacetilcarbamoil)fumagilol , Fosfoproteínas/genética , Sesquiterpenos/farmacologia , Transdução de Sinais/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismo , Proteínas Wnt/metabolismo , Peixe-Zebra , beta Catenina/metabolismoRESUMO
Previous mode of action studies identified methionine aminopeptidase 2 (MetAP-2) as the target of the antiangiogenic natural product fumagillin and its drug candidate analog, TNP-470. We report here that TNP-470-mediated MetAP-2 inhibition blocks noncanonical Wnt signaling, which plays a critical role in development, cell differentiation, and tumorigenesis. Consistent with this finding, antisense MetAP-2 morpholino oligonucleotide injection in zebrafish embryos phenocopies gastrulation defects seen in noncanonical Wnt5 loss-of-function zebrafish mutants. MetAP-2 inhibition or depletion blocks signaling downstream of the Wnt receptor Frizzled, but upstream of Calmodulin-dependent Kinase II, RhoA, and c-Jun N-terminal Kinase. Moreover, we demonstrate that TNP-470 does not block the canonical Wnt/beta-catenin pathway. Thus, TNP-470 selectively regulates noncanonical over canonical Wnt signaling and provides a unique means to explore and dissect the biological systems mediated by these pathways.
