The ubiquitin-proteasome system maintains protein homoeostasis, underpins the cell cycle, and is dysregulated in cancer. However, the role of individual E3 ubiquitin ligases, which mediate the final step in ubiquitin-mediated proteolysis, remains incompletely understood. Identified through screening for cancer-specific endogenous retroviral transcripts, we show that the little-studied E3 ubiquitin ligase HECTD2 exerts dominant control of tumour progression in melanoma.
View Article and Find Full Text PDFIn the version of this article originally published, the names of three authors were incorrect. The authors were listed as "Coral Fustero-Torres", "Elena Pineiro" and "Melchor Sánchez-Martínez". Their respective names are "Coral Fustero-Torre", "Elena Piñeiro-Yáñez" and "Melchor Sanchez-Martinez".
View Article and Find Full Text PDFThe brain microenvironment imposes a particularly intense selective pressure on metastasis-initiating cells, but successful metastases bypass this control through mechanisms that are poorly understood. Reactive astrocytes are key components of this microenvironment that confine brain metastasis without infiltrating the lesion. Here, we describe that brain metastatic cells induce and maintain the co-option of a pro-metastatic program driven by signal transducer and activator of transcription 3 (STAT3) in a subpopulation of reactive astrocytes surrounding metastatic lesions.
View Article and Find Full Text PDFBackground: Determining the function of regulatory elements is fundamental for our understanding of development, disease and evolution. However, the sequence features that mediate these functions are often unclear and the prediction of tissue-specific expression patterns from sequence alone is non-trivial. Previous functional studies have demonstrated a link between PBX-HOX and MEIS/PREP binding interactions and hindbrain enhancer activity, but the defining grammar of these sites, if any exists, has remained elusive.
View Article and Find Full Text PDFBackground: GLI2, a zinc finger transcription factor, mediates Sonic hedgehog signaling, a critical pathway in vertebrate embryogenesis. GLI2 has been implicated in diverse set of embryonic developmental processes, including patterning of central nervous system and limbs. In humans, mutations in GLI2 are associated with several developmental defects, including holoprosencephaly and polydactyly.
View Article and Find Full Text PDFUrochordates are the closest relatives of vertebrates and at the larval stage, possess a characteristic bilateral chordate body plan. In vertebrates, the genes that orchestrate embryonic patterning are in part regulated by highly conserved non-coding elements (CNEs), yet these elements have not been identified in urochordate genomes. Consequently the evolution of the cis-regulatory code for urochordate development remains largely uncharacterised.
View Article and Find Full Text PDFHedgehog (Hh) moves from the producing cells to regulate the growth and development of distant cells in a variety of tissues. Here, we have investigated the mechanism of Hh release from the producing cells to form a morphogenetic gradient in the Drosophila wing imaginal disk epithelium. We describe that Hh reaches both apical and basolateral plasma membranes, but the apical Hh is subsequently internalized in the producing cells and routed to the basolateral surface, where Hh is released to form a long-range gradient.
View Article and Find Full Text PDFIn order for neurons to perform their function, they must establish a highly polarized morphology characterized, in most of the cases, by a single axon and multiple dendrites. Herein we find that the evolutionarily conserved protein Kidins220 (kinase D-interacting substrate of 220-kDa), also known as ARMS (ankyrin repeat-rich membrane spanning), a downstream effector of protein kinase D and neurotrophin and ephrin receptors, regulates the establishment of neuronal polarity and development of dendrites. Kidins220/ARMS gain and loss of function experiments render severe phenotypic changes in the processes extended by hippocampal neurons in culture.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2009
Endosomes and endosomal vesicles (EVs) rapidly move along cytoskeletal filaments allowing them to exchange proteins and lipids between different endosomal compartments, lysosomes, the trans-Golgi network (TGN), and the plasma membrane. The precise mechanisms that connect membrane traffic between the TGN and perinuclear endosomal compartments with motor-protein driven transport have largely remained elusive. Here we show that Gadkin (also termed gamma-BAR), a peripheral membrane protein localized to the TGN and to TGN-derived EVs, directly associates with the clathrin adaptor AP-1 and with the motor protein kinesin KIF5, thereby potentially regulating EV dynamics.
View Article and Find Full Text PDFPoxviruses, such as vaccinia virus (VV), replicate their DNA in endoplasmic-reticulum-enclosed cytoplasmic sites. Here, we compare the dynamics of the VV replication sites with those of the attenuated strain, modified VV Ankara (MVA). By live-cell imaging, small, early replication sites of both viruses undergo motility typical of microtubule (MT)-motor-mediated movement.
View Article and Find Full Text PDFGenetic analysis of familial Alzheimer's disease has revealed that mutations in the gamma-secretase enzyme presenilin promote toxic Abeta secretion; however, presenilin mutations might also influence tau hyperphosphorylation and neurodegeneration through gamma-secretase-independent mechanisms. To address this possibility and determine whether other components of the gamma-secretase complex possess similar regulatory functions, we analyzed the roles of presenilin, nicastrin, and aph-1 in a Drosophila model for tau-induced neurodegeneration. Here, we show that presenilin and nicastrin prevent tau toxicity by modulating the PI3K/Akt/GSK3beta phosphorylation pathway, whereas aph-1 regulates aPKC/PAR-1 activities.
View Article and Find Full Text PDFThe vaccinia virus (VV) I3L gene product is a single-stranded DNA-binding protein made early in infection that localizes to the cytoplasmic sites of viral DNA replication (S. C. Rochester and P.
View Article and Find Full Text PDFVaccinia virus (VV), a member of the poxvirus family, is unique among most other DNA viruses in that both transcription and DNA replication occur in the cytoplasm of the host cell. It was recently shown by electron microscopy (EM) that soon after viral DNA synthesis is initiated in HeLa cells, the replication sites become enwrapped by the membrane of the endoplasmic reticulum (ER). In the same study, a novel VV membrane protein, the E8R gene product, that may play a role in the ER wrapping process was identified (N.
View Article and Find Full Text PDFVirus assembly, a late event in the life cycle of vaccinia virus (VV), is preceded by a number of steps that all occur in the cytoplasm of the infected host cell: virion entry, delivery of the viral core into the cytoplasm, and transcription from these cores of early mRNAs, followed by the process of DNA replication. In the present study the quantitative and structural relationships between these distinct steps of VV morphogenesis were investigated. We show that viral RNA and DNA synthesis increases linearly with increasing amounts of incoming cores.
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