Translocación del centro organizador de microtúbulos como regulador de la sinapsis inmune y la activación del linfocito T

Tesis doctoral inédita realizada en la Universidad Autónoma de Madrid. Departamento de Bioquímica. Fecha de lectura: 10 de Diciembre de 201

The disease-linked Glu-26-Lys mutant version of Coronin 1A exhibits pleiotropic and pathwayspecific signaling defects

This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License.Coronin 1A (Coro1A) is involved in cytoskeletal and signaling events, including the regulation of Rac1 GTPase– and myosin II–dependent pathways. Mutations that generate truncated or unstable Coro1A proteins cause immunodeficiencies in both humans and rodents. However, in the case of the peripheral T-cell–deficient (Ptcd) mouse strain, the immunodeficiency is caused by a Glu-26-Lys mutation that targets a surface-exposed residue unlikely to affect the intramolecular architecture and stability of the protein. Here we report that this mutation induces pleiotropic effects in Coro1A protein, including the exacerbation of Coro1A-dependent actin-binding and -bundling activities; the formation of large meshworks of Coro1AE26K-decorated filaments endowed with unusual organizational, functional, and staining properties; and the elimination of Coro1A functions associated with both Rac1 and myosin II signaling. By contrast, it does not affect the ability of Coro1A to stimulate the nuclear factor of activated T-cells (NF-AT). Coro1AE26K is not a dominant-negative mutant, indicating that its pathological effects are derived from the inability to rescue the complete loss of the wild-type counterpart in cells. These results indicate that Coro1AE26K behaves as either a recessive gain-of-function or loss-of-function mutant protein, depending on signaling context and presence of the wild-type counterpart in cells.This work has been supported by grants to X.R.B. from the Castilla-León Autonomous Government (CSI101U13), the Spanish Ministry of Economy and Competitiveness (SAF2012-31371, RD12/0036/0002), the Solórzano Foundation, and the Ramón Areces Foundation. Spanish government–sponsored funding is partially supported by the European Regional Development Fund.Peer Reviewe

MTOC translocation modulates IS formation and controls sustained T cell signaling

The translocation of the microtubule-organizing center (MTOC) toward the nascent immune synapse (IS) is an early step in lymphocyte activation initiated by T cell receptor (TCR) signaling. The molecular mechanisms that control the physical movement of the lymphocyte MTOC remain largely unknown. We have studied the role of the dynein–dynactin complex, a microtubule-based molecular motor, in the process of T cell activation during T cell antigen–presenting cell cognate immune interactions. Impairment of dynein–dynactin complex activity, either by overexpressing the p50-dynamitin component of dynactin to disrupt the complex or by knocking down dynein heavy chain expression to prevent its formation, inhibited MTOC translocation after TCR antigen priming. This resulted in a strong reduction in the phosphorylation of molecules such as ζ chain–associated protein kinase 70 (ZAP70), linker of activated T cells (LAT), and Vav1; prevented the supply of molecules to the IS from intracellular pools, resulting in a disorganized and dysfunctional IS architecture; and impaired interleukin-2 production. Together, these data reveal MTOC translocation as an important mechanism underlying IS formation and sustained T cell signaling

Computational and in vitro Pharmacodynamics Characterization of 1A-116 Rac1 Inhibitor: Relevance of Trp56 in Its Biological Activity

In the last years, the development of new drugs in oncology has evolved notably. In particular, drug development has shifted from empirical screening of active cytotoxic compounds to molecularly targeted drugs blocking specific biologic pathways that drive cancer progression and metastasis. Using a rational design approach, our group has developed 1A-116 as a promising Rac1 inhibitor, with antitumoral and antimetastatic effects in several types of cancer. Rac1 is over activated in a wide range of tumor types and and it is one of the most studied proteins of the Rho GTPase family. Its role in actin cytoskeleton reorganization has effects on endocytosis, vesicular trafficking, cell cycle progression and cellular migration. In this context, the regulatory activity of Rac1 affects several key processes in the course of the cancer including invasion and metastasis. The purpose of this preclinical study was to focus on the mode of action of 1A-116, conducting an interdisciplinary approach with in silico bioinformatics tools and in vitro assays. Here, we demonstrate that the tryptophan 56 residue is necessary for the inhibitory effects of 1A-116 since this compound interferes with protein-protein interactions (PPI) of Rac1GTPase involving several GEF activators. 1A116 is also able to inhibit the oncogenic Rac1P29S mutant protein, one of the oncogenic drivers found in sun-exposed melanoma. It also inhibits numerous Rac1-regulated cellular processes such as membrane ruffling and lamellipodia formation. These results deepen our knowledge of 1A-116 inhibition of Rac1 and its biological impact on cancer progression. They also represent a good example of how in silico analyses represent a valuable approach for drug development.Fil: González, Nazareno. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cardama, Georgina Alexandra. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chinestrad, Patricio Manuel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Farmacología Molecular; ArgentinaFil: Robles Valero, Javier. Universidad de Salamanca; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Rodríguez Fdez, Sonia. Universidad de Salamanca; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Lorenzo Martín, L. Francisco. Universidad de Salamanca; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Bustelo, Xosé R.. Universidad de Salamanca; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Lorenzano Menna, Pablo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Farmacología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Miro-1 links mitochondria and microtubule dynein motors to control lymphocyte migration and polarity

The recruitment of leukocytes to sites of inflammation is crucial for a functional immune response. In the present work, we explored the role of mitochondria in lymphocyte adhesion, polarity, and migration. We show that during adhesion to the activated endothelium under physiological flow conditions, lymphocyte mitochondria redistribute to the adhesion zone together with the microtubule-organizing center (MTOC) in an integrin-dependent manner. Mitochondrial redistribution and efficient lymphocyte adhesion to the endothelium require the function of Miro-1, an adaptor molecule that couples mitochondria to microtubules. Our data demonstrate that Miro-1 associates with the dynein complex. Moreover, mitochondria accumulate around the MTOC in response to the chemokine CXCL12/SDF-1α this redistribution is regulated by Miro-1. CXCL12-dependent cell polarization and migration are reduced in Miro-1-silenced cells, due to impaired myosin II activation at the cell uropod and diminished actin polymerization. These data point to a key role of Miro-1 in the control of lymphocyte adhesion and migration through the regulation of mitochondrial redistribution.This study was supported by SAF2011-25834 from the Spanish Ministry of Science and Innovation, INDISNET-S2011/BMD-2332 from the Comunidad de Madrid, Red Cardiovascular RD 12-0042-0056 from Instituto Salud Carlos III (ISCIII), and ERC-2011-AdG 294340- GENTRIS. J.M.G.-G. received salary support from the Miguel Servet (CP11/00145) ISCIII program. R.V.-B. was supported by a Juan de la Cierva postdoctoral contract from the Spanish Ministry of Economy and Competiveness (JCI-2011-09663

Immunosuppression-independent role of regulatory T cells against hypertension-driven renal dysfunctions

Hypertension-associated cardiorenal diseases represent one of the heaviest burdens for current health systems. In addition to hemodynamic damage, recent results have revealed that hematopoietic cells contribute to the development of these diseases by generating proinflammatory and profibrotic environments in the heart and kidney. However, the cell subtypes involved remain poorly characterized. Here we report that CD39+ regulatory T (TREG) cells utilize an immunosuppression-independent mechanism to counteract renal and possibly cardiac damage during angiotensin II (AngII)-dependent hypertension. This mechanism relies on the direct apoptosis of tissue-resident neutrophils by the ecto-ATP diphosphohydrolase activity of CD39. In agreement with this, experimental and genetic alterations in TREG/TH cell ratios have a direct impact on tissue-resident neutrophil numbers, cardiomyocyte hypertrophy, cardiorenal fibrosis, and, to a lesser extent, arterial pressure elevation during AngII-driven hypertension. These results indicate that TREG cells constitute a first protective barrier against hypertension-driven tissue fibrosis and, in addition, suggest new therapeutic avenues to prevent hypertension-linked cardiorenal diseases.This work has been supported by grants from the Castilla-León Autonomous Government (CSI101U13), the Spanish Ministry of Economy and Competitiveness (SAF2012-31371, RD12/0036/0002), Worldwide Cancer Research, the Solórzano Foundation, and the Ramón Areces Foundation to X.R.B. P.M. is funded by the Spanish Ministry of Economy and Competitiveness (SAF2011-27330). S.F., M.M.-M., J.R.-V., and A.M.-M. were supported by the Spanish Ministry of Economy and Competitiveness through BES-2010-031386, CSIC JAE-Doc, Juan de la Cierva, and BES-2009-016103 contracts, respectively. Spanish government-sponsored funding to X.R.B. is partially supported by the European Regional Development Fund.Peer Reviewe

Everolimus safety and efficacy for renal angiomyolipomas associated with tuberous sclerosis complex: A Spanish expanded access trial

Background: Renal angiomyolipomas (AML) are usual manifestations of tuberous sclerosis complex (TSC) that may cause aneurism-related haemorrhages and renal impairment. Everolimus has emerged as an alternative to surgery/embolization. We provide further insight into everolimus safety and efficacy for TSC-related AML. Methods: This was a Spanish expanded access trial including patients aged ≥18 years with TSC-related AML. They received 10 mg everolimus once daily until AML progression, unacceptable toxicity, death/withdrawal, commercialisation for TSC-related AML, or 1 year after first patient enrolment. The primary outcome was dose-limiting safety according to grade 3/4 adverse events, serious adverse events, or adverse events leading to treatment modification. Secondary outcomes included overall safety and efficacy. Results: Nineteen patients were enrolled and received everolimus for a median of 6.6 (5.3-10.9) months. Eleven (57.9 %) remained on 10 mg/day throughout the study and eight (42.1 %) required treatment modifications due to adverse events; none permanently discontinued treatment. Adverse events were overall grade 1/2 and most frequently included aphthous stomatitis/mucosal inflammation, hypercholesterolaemia/hypertriglyceridaemia, urinary tract infection, hypertension, dermatitis acneiform, and insomnia. Four (21.1 %) patients experienced grade 3 adverse events, none was grade 4, and only one (5.3 %) was serious (pneumonia). AML volume was reduced ≥30 % in 11 (57.9 %) patients and ≥50 % in 9 (47.4 %); none progressed. Right and left kidney sizes decreased in 16 and 14 patients, respectively. Conclusions: These findings support the benefit of everolimus for renal AML due to a manageable safety profile accompanied by reduced AML and kidney volumes. Trial registration: EudraCT number 2012-005397-63; date of registration 22 Nov 2012.This work was funded by Novartis Farmacéutica S.A., which was involved in study design, data analysis and interpretation, and writing of the manuscrip

A hotspot mutation targeting the R-RAS2 GTPase acts as a potent oncogenic driver in a wide spectrum of tumors

A missense change in RRAS2 (Gln to Leu), analogous to the Gln-to-Leu mutation of RAS oncoproteins, has been identified as a long-tail hotspot mutation in cancer and Noonan syndrome. However, the relevance of this mutation for in vivo tumorigenesis remains understudied. Here we show, using an inducible knockin mouse model, that R-Ras2 triggers rapid development of a wide spectrum of tumors when somatically expressed in adult tissues. These tumors show limited overlap with those originated by classical Ras oncogenes. R-Ras2-driven tumors can be classified into different subtypes according to therapeutic susceptibility. Importantly, the most relevant R-Ras2-driven tumors are dependent on mTORC1 but independent of phosphatidylinositol 3-kinase-, MEK-, and Ral guanosine diphosphate (GDP) dissociation stimulator. This pharmacological vulnerability is due to the extensive rewiring by R-Ras2 of pathways that orthogonally stimulate mTORC1 signaling. These findings demonstrate that RRAS2 is a bona fide oncogenic driver and unveil therapeutic strategies for patients with cancer and Noonan syndrome bearing RRAS2 mutations.We thank M. Blázquez and the personnel of the CIC Flow Cytometry, Microscopy, Pathology, and Genomics Units for expert technical work. X.R.B.’s project leading to these results has received funding from the Spanish Association against Cancer (GC16173472GARC), the Castilla-León government (CSI252P18, CSI145P20, and CLC-2017-01), the RTI2018-096481-B-100 grant cofounded by MCIN/AEI/10.13039/501100011033 and the European Research Development Fund “A way of making Europe” of the European Union, and “la Caixa” Banking Foundation (HR20-00164). X.R.B.’s institution is supported by the Programa de Apoyo a Planes Estratégicos de Investigación de Estructuras de Investigación de Excelencia of the Castilla-León government (CLC-2017-01). J.R.-V. received funding from the Carlos III Health Institute (PI20/01724). J.R.-V.’s contract is supported by a senior postdoctoral contract of the Spanish Association against Cancer. L.C.’s contract was supported by contracts from the Spanish Association against Cancer and the CLC-2017-01 grant. L.F.L.-M.’s contract was mostly supported by funding from the Spanish Ministry of Education, Culture and Sports (FPU13/02923) and, subsequently, by the CLC-2017-01 grant. R.C. was supported by a predoctoral contract from the MSI (BES-2016-0077909) and the CLC-2017-01 grant

Clathrin regulates lymphocyte migration by driving actin accumulation at the cellular leading edge

Lymphocyte migration, which is essential for effective immune responses, belongs to the so-called amoeboid migration. The lymphocyte migration is up to 100 times faster than between mesenchymal and epithelial cell types. Migrating lymphocytes are highly polarized in three well-defined structural and functional zones: uropod, medial zone, and leading edge (LE). The actiomyosin-dependent driving force moves forward the uropod, whereas massive actin rearrangements protruding the cell membrane are observed at the LE. These actin rearrangements resemble those observed at the immunological synapse driven by clathrin, a protein normally involved in endocytic processes. Here, we used cell lines as well as primary lymphocytes to demonstrate that clathrin and clathrin adaptors colocalize with actin at the LE of migrating lymphocytes, but not in other cellular zones that accumulate both clathrin and actin. Moreover, clathrin and clathrin adaptors, including Hrs, the clathrin adaptor for multivesicular bodies, drive local actin accumulation at the LE. Clathrin recruitment at the LE resulted necessary for a complete cell polarization and further lymphocyte migration in both 2D and 3D migration models. Therefore, clathrin, including the clathrin population associated to internal vesicles, controls lymphocyte migration by regulating actin rearrangements occurring at the LE.This work was supported by the grants from the Spanish Ministry of Science and Technology (MICINN; BFU2011-29450 to E.V.) and Ministry of Economy and Competitiveness (MINECO; SAF2014-56716-REDT and BFU2014-59585-R to E.V., SAF2011-25834 to F.S.M., SAF2014-58895-JIN to A.C.A and BFU2014-54181-P to J.L.C.), the Madrid regional government (INDISNET-S2011/BMD-2332 to F.S.M.) and the European Research Council (ERC-2011-AdG 294340-GENTRIS to F.S.M.). We are grateful to the “Centro de Transfusión” of the “Comunidad Autónoma de Madrid” for providing the Buffy Coats

Activating mutations and translocations in the guanine exchange factor VAV1 in peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of non-Hodgkin lymphomas frequently associated with poor prognosis and for which genetic mechanisms of transformation remain incompletely understood. Using RNA sequencing and targeted sequencing, here we identify a recurrent in-frame deletion (VAV1 Δ778-786) generated by a focal deletion-driven alternative splicing mechanism as well as novel VAV1 gene fusions (VAV1-THAP4, VAV1-MYO1F, and VAV1-S100A7) in PTCL. Mechanistically these genetic lesions result in increased activation of VAV1 catalytic-dependent (MAPK, JNK) and non-catalytic-dependent (nuclear factor of activated T cells, NFAT) VAV1 effector pathways. These results support a driver oncogenic role for VAV1 signaling in the pathogenesis of PTCL