Bett C.,University of California at San Diego |
Fernandez-Borges N.,Center for Cooperative Research in Biosciences Bio |
Kurt T.D.,University of California at San Diego |
Lucero M.,University of California at San Diego |
And 5 more authors.
FASEB Journal | Year: 2012
Prions are misfolded, aggregated conformers of the prion protein that can be transmitted between species. The precise determinants of interspecies transmission remain unclear, although structural similarity between the infectious prion and host prion protein is required for efficient conversion to the misfolded conformer. The β2-α2 loop region of endogenous prion protein, PrPC, has been implicated in barriers to prion transmission. We recently discovered that conversion was efficient when incoming and host prion proteins had similar β2-α2 loop structures; however, the roles of primary vs. secondary structural homology could not be distinguished. Here we uncouple the effect of primary and secondary structural homology of the β2-α2 loop on prion conversion. We inoculated prions from animals having a disordered or an ordered β2-α2 loop into mice having a disordered loop or an ordered loop due to a single residue substitution (D167S). We found that prion conversion was driven by a homologous primary structure and occurred independently of a homologous secondary structure. Similarly, cell-free conversion using PrPCfrom mice with disordered or ordered loops and prions from 5 species correlated with primary but not secondary structural homology of the loop. Thus, our findings support a model in which efficient interspecies prion conversion is determined by small stretches of the primary sequence rather than the secondary structure of PrP.© FASEB.
Lorente M.,Complutense University of Madrid |
Torres S.,Complutense University of Madrid |
Salazar M.,Complutense University of Madrid |
Salazar M.,Research Center Biomedica en Red Sobre Enfermedades Neurodegenerativas |
And 14 more authors.
Cell Death and Differentiation | Year: 2011
Identifying the molecular mechanisms responsible for the resistance of gliomas to anticancer treatments is an issue of great therapeutic interest. Δ 9-Tetrahydrocannabinol (THC), the major active ingredient of marijuana, and other cannabinoids inhibit tumor growth in animal models of cancer, including glioma, an effect that relies, at least in part, on the stimulation of autophagy-mediated apoptosis in tumor cells. Here, by analyzing the gene expression profile of a large series of human glioma cells with different sensitivity to cannabinoid action, we have identified a subset of genes specifically associated to THC resistance. One of these genes, namely that encoding the growth factor midkine (Mdk), is directly involved in the resistance of glioma cells to cannabinoid treatment. We also show that Mdk mediates its protective effect via the anaplastic lymphoma kinase (ALK) receptor and that Mdk signaling through ALK interferes with cannabinoid-induced autophagic cell death. Furthermore, in vivo Mdk silencing or ALK pharmacological inhibition sensitizes cannabinod-resistant tumors to THC antitumoral action. Altogether, our findings identify Mdk as a pivotal factor involved in the resistance of glioma cells to THC pro-autophagic and antitumoral action, and suggest that selective targeting of the Mdk/ALK axis could help to improve the efficacy of antitumoral therapies for gliomas. © 2011 Macmillan Publishers Limited All rights reserved.
PubMed | New York University, Biodonostia Research Institute, Girona Biomedical Research Institute IDIBGI, Hospitalet Of Llobregat and 24 more.
Type: | Journal: Oncogene | Year: 2016
Inhibitors of the mechanistic target of rapamycin (mTOR) are currently used to treat advanced metastatic breast cancer. However, whether an aggressive phenotype is sustained through adaptation or resistance to mTOR inhibition remains unknown. Here, complementary studies in human tumors, cancer models and cell lines reveal transcriptional reprogramming that supports metastasis in response to mTOR inhibition. This cancer feature is driven by EVI1 and SOX9. EVI1 functionally cooperates with and positively regulates SOX9, and promotes the transcriptional upregulation of key mTOR pathway components (REHB and RAPTOR) and of lung metastasis mediators (FSCN1 and SPARC). The expression of EVI1 and SOX9 is associated with stem cell-like and metastasis signatures, and their depletion impairs the metastatic potential of breast cancer cells. These results establish the mechanistic link between resistance to mTOR inhibition and cancer metastatic potential, thus enhancing our understanding of mTOR targeting failure.Oncogene advance online publication, 19 December 2016; doi:10.1038/onc.2016.427.
PubMed | McGill University, University of Granada, An Najah National University, Leibniz Institute for Molecular Pharmacology and 3 more.
Type: | Journal: The Journal of biological chemistry | Year: 2016
Phosphatases of regenerating liver (PRLs), the most oncogenic of all protein tyrosine phosphatases (PTPs), play a critical role in metastatic progression of cancers. Recent findings established a new paradigm by uncovering that their association with magnesium transporters of the Cyclin M (CNNM) family causes intracellular magnesium levels that promotes oncogenic transformation. On the other hand, it has recently been highlighted essential roles of the CNNM family in regulation of the circadian rhythm, and reproduction. Here, we describe the crystal structure of PRL-1 in complex with the Bateman module of CNNM2 (CNNM2BAT), which consists of two cystathionine -synthase (CBS) domains (IPR000664) and represents an intracellular regulatory module of the transporter. The structure reveals a heterotetrameric association, consisting of a disc-like homodimer of CNNM2BAT bound to two independent PRL-1 molecules, each one located at opposite tips of the disc. The structure highlights the key role played by residue D558 at the extended loop of the CBS2 motif of CNNM2 in maintaining the association between the two proteins and proves that the interaction between CNNM2 and PRL-1 occurs via the catalytic domain of the phosphatase. Our data shed new light on the structural basis underlying the interaction between PRL phosphatases and CNNM transporters and provides a hypothesis about the molecular mechanism by which PRL-1, upon binding to CNNM2, might increase the intracellular concentration of Mg2+ thereby contributing to tumor progression and metastasis. The availability of this structure sets the basis for the rational design of compounds modulating PRL-1 and CNNM2 activities.
PubMed | University of Kentucky, Creighton University, Autonomous University of Barcelona, Colorado State University and 3 more.
Type: | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2017
Adaptation of prions to new species is thought to reflect the capacity of the host-encoded cellular form of the prion protein (PrP
PubMed | Daegu Gyeongbuk Institute of Science and Technology, University of Colorado at Denver, University of Vermont, University of Connecticut Health Center and 2 more.
Type: Journal Article | Journal: Immunity | Year: 2016
Mitochondrial respiration is regulated in CD8(+) Tcells during the transition from naive to effector and memory cells, but mechanisms controlling this process have not been defined. Here we show that MCJ (methylation-controlled J protein) acted as an endogenous break for mitochondrial respiration in CD8(+) Tcells by interfering with the formation of electron transport chain respiratory supercomplexes. Metabolic profiling revealed enhanced mitochondrial metabolism in MCJ-deficient CD8(+) Tcells. Increased oxidative phosphorylation and subcellular ATP accumulation caused by MCJ deficiency selectively increased the secretion, but not expression, of interferon-. MCJ also adapted effector CD8(+) Tcell metabolism during the contraction phase. Consequently, memory CD8(+) Tcells lacking MCJ provided superior protection against influenza virus infection. Thus, MCJ offers a mechanism for fine-tuning CD8(+) Tcell mitochondrial metabolism as an alternative to modulating mitochondrial mass, an energetically expensive process. MCJ could be a therapeutic target to enhance CD8(+) Tcell responses.
An update on the use of benzoate, phenylacetate and phenylbutyrate ammonia scavengers for interrogating and modifying liver nitrogen metabolism and its implications in urea cycle disorders and liver disease
PubMed | University Hospital of Cruces and Center for Cooperative Research in Biosciences bio
Type: | Journal: Expert opinion on drug metabolism & toxicology | Year: 2016
Ammonia-scavenging drugs, benzoate and phenylacetate (PA)/phenylbutyrate (PB), modulate hepatic nitrogen metabolism mainly by providing alternative pathways for nitrogen disposal. Areas covered: We review the major findings and potential novel applications of ammonia-scavenging drugs, focusing on urea cycle disorders and liver disease. Expert opinion: For over 40years, ammonia-scavenging drugs have been used in the treatment of urea cycle disorders. Recently, the use of these compounds has been advocated in acute liver failure and cirrhosis for reducing hyperammonemic-induced hepatic encephalopathy. The efficacy and mechanisms underlying the antitumor effects of these ammonia-scavenging drugs in liver cancer are more controversial and are discussed in the review. Overall, as ammonia-scavenging drugs are usually safe and well tolerated among cancer patients, further studies should be instigated to explore the role of these drugs in liver cancer. Considering the relevance of glutamine metabolism to the progression and resolution of liver disease, we propose that ammonia-scavenging drugs might also be used to non-invasively probe liver glutamine metabolism in vivo. Finally, novel derivatives of classical ammonia-scavenging drugs with fewer and less severe adverse effects are currently being developed and used in clinical trials for the treatment of acute liver failure and cirrhosis.
Uysal-Onganer P.,Imperial College London |
Kypta R.M.,Imperial College London |
Kypta R.M.,Center for Cooperative Research in Biosciences bio
Acta Physiologica | Year: 2012
Genetic studies of Wnt11 have revealed many insights into the roles and regulation of Wnt11, particularly during development. New tools to study Wnt11 have recently become available, making it timely to review the literature regarding this unique Wnt family member. In this study, we focus on mammalian Wnt11, describing its main sites of expression during development, and how the Wnt11 gene is regulated. We highlight an emerging theme in which canonical Wnt signals regulate Wnt11 expression through transcription factors in addition to, or other than, Tcf/LEF family members. We also discuss the frizzled family and other receptors that bind to Wnt11, the intracellular kinases and small GTPases that act downstream of Wnt11, and the effects of Wnt11 on Wnt/β-catenin signalling. Finally, we elaborate on the relevance of Wnt11 to human cancer, where it appears to be important both for proliferation and/or survival during normal differentiation and for migration/invasion. © 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.
Uysal-Onganer P.,Imperial College London |
Kawano Y.,Imperial College London |
Caro M.,Center for Cooperative Research in Biosciences bio |
Walker M.M.,Imperial College London |
And 5 more authors.
Molecular Cancer | Year: 2010
Background: Wnt-11 is a secreted protein that modulates cell growth, differentiation and morphogenesis during development. We previously reported that Wnt-11 expression is elevated in hormone-independent prostate cancer and that the progression of prostate cancer from androgen-dependent to androgen-independent proliferation correlates with a loss of mutual inhibition between Wnt-11- and androgen receptor-dependent signals. However, the prevalence of increased expression of Wnt-11 in patient tumours and the functions of Wnt-11 in prostate cancer cells were not known.Results: Wnt-11 protein levels in prostate tumours were determined by immunohistochemical analysis of prostate tumour tissue arrays. Wnt-11 protein was elevated in 77/117 of tumours when compared with 27 benign prostatic hypertrophy specimens and was present in 4/4 bone metastases. In addition, there was a positive correlation between Wnt-11 expression and PSA levels above 10 ng/ml. Androgen-depleted LNCaP prostate cancer cells form neurites and express genes associated with neuroendocrine-like differentiation (NED), a feature of prostate tumours that have a poor prognosis. Since androgen-depletion increases expression of Wnt-11, we examined the role of Wnt-11 in NED. Ectopic expression of Wnt-11 induced expression of NSE and ASCL1, which are markers of NED, and this was prevented by inhibitors of cyclic AMP-dependent protein kinase, consistent with the known role of this kinase in NED. In contrast, Wnt-11 did not induce NSE expression in RWPE-1 cells, which are derived from benign prostate, suggesting that the role of Wnt-11 in NED is specific to prostate cancer. In addition, silencing of Wnt-11 expression in androgen-depleted LNCaP cells prevented NED and resulted in apoptosis. Silencing of Wnt-11 gene expression in androgen-independent PC3 cells also reduced expression of NSE and increased apoptosis. Finally, silencing of Wnt-11 reduced PC3 cell migration and ectopic expression of Wnt-11 promoted LNCaP cell invasion.Conclusions: These observations suggest that the increased level of Wnt-11 found in prostate cancer contributes to tumour progression by promoting NED, tumour cell survival and cell migration/invasion, and may provide an opportunity for novel therapy in prostate cancer. © 2010 Uysal-Onganer et al; licensee BioMed Central Ltd.
Peng H.,Cedars Sinai Medical Center |
Li T.W.H.,Cedars Sinai Medical Center |
Yang H.,Cedars Sinai Medical Center |
Yang H.,University of Southern California |
And 4 more authors.
American Journal of Pathology | Year: 2015
Methionine adenosyltransferase 2B (MAT2B) encodes for variant proteins V1 and V2 that interact with GIT1 to increase ERK activity and growth in human liver and colon cancer cells. MAT2B or GIT1 overexpression activates MEK. This study explores the mechanism for MEK activation. We examined protein-protein interactions by co-immunoprecipitation and verified by confocal microscopy and pull-down assay using recombinant or in vitro translated proteins. Results were confirmed in an orthotopic liver cancer model. We found that MAT2B and GIT1-mediated MEK1/2 activation was not mediated by PAK1 or Src in HepG2 or RKO cells. Instead, MAT2B and GIT1 interact with B-Raf and c-Raf and enhance recruitment of Raf proteins to MEK1/2. MAT2B-GIT1 activates c-Raf, which is the key mediator for MEK/12 activation, because this still occurred in RKO cells that express constitutively active B-Raf mutant. The mechanism lies with the ability of MAT2B-GIT1 to activate Ras and promote B-Raf/c-Raf heterodimerization. Interestingly, MAT2B but not GIT1 can directly interact with Ras, which increases protein stability. Finally, increased Ras-Raf-MEK signaling occurred in phenotypically more aggressive liver cancers overexpressing MAT2B variants and GIT1. In conclusion, interaction between MAT2B and GIT1 serves as a scaffold and facilitates signaling in multiple steps of the Ras/Raf/MEK/ERK pathway, further emphasizing the importance of MAT2B/GIT1 interaction in cancer growth. © 2015 American Society for Investigative Pathology.