Serina 284 como regulador de la dimerización y de la localización celular de ERK2

ABSTRACT: Signals conveyed through ERK1/2 Mitogen-Activated Protein Kinases are well-known to play a critical role in cancer initiation, progression, and therapy resistance. It has been demonstrated that the balance between ERK monomers and dimers and cytoplasmic and nuclear sub-signals are critical for the biological outcomes resulting from ERK activation subcellular distribution. Studying the efficacy of DEL22379, a new compound that blocks ERK dimerization, we made the startling observation that ERK dimerization was restricted to mammalians. A comparison of the ERK2 sequence through the evolutionary scale unveiled that Serine284 (H.sapiens) was conserved in those species in which ERK2 dimerized, being suggestive of playing some role in ERK2 dimerization. Indeed, we have shown that Ser284 is necessary but not sufficient for ERK2 dimerization. Moreover, Ser284 is a phosphorylatable residue of ERK2, being a cytoplasmic marker of active ERK2. This phosphorylation, mediated by MEK1 and AKT1, enhances ERK affinity for the scaffold KSR1 and reduces ERK2 interaction with nuclear shuttles like IMP7; being critical for the regulation of ERK2 subcellular distribution. In addition, the sensitivity to BRAF mutant melanoma cells to vemurafenib treatment correlates with higher levels of phospho-Ser284. Thus, p-Ser284 levels could be used as a predictive biomarker for the response to vemurafenib in BRAF positive melanoma patients.RESUMEN: La señalización a través de la ruta de las MAP kinasas ERK1/2 está claramente implicada en el desarrollo y progresión tumoral, así como en la aparición de resistencias. Se ha demostrado que el equilibrio entre los monómeros y los dímeros de ERK y su señalización citoplasmática y nuclear son críticas para los efectos biológicos debidos a su activación en función de su distribución subcelular. Estudiando los efectos de DEL22379, un inhibidor de la dimerización de ERK, hicimos el sorprendente descubrimiento de que ERK2 dimeriza solo en mamíferos. A través de la comparación de la secuencia de ERK en distintas especies observamos que el residuo Ser284 (en humano) estaba conservado en aquellas especies donde ERK dimeriza, lo que sugiere que podría jugar un papel importante en la dimerización de ERK2. En efecto, hemos demostrado que la fosforilación de la Ser284 es necesaria pero no suficiente para la dimerización de ERK2. Dicha fosforilación, que es mediada por MEK1 y AKT1, aumenta la afinidad de ERK2 por el scaffold KSR1 y reduce la afinidad por proteínas transportadoras nucleares como la IMP7; siendo crítica para la regulación de la distribución subcelular de ERK2. Además, aquellas células tumorales de melanoma portadoras de la mutación en BRAF, sensibles al tratamiento con Vemurafenib, muestran una mayor fosforilación en Ser284. Por tanto, los niveles de p-Ser284 podrían servir como biomarcador predictivo de respuesta al tratamiento con Vemurafenib en pacientes con melanoma.La presente Tesis Doctoral titulada “Serine 284 as a regulator of ERK2 dimerization and cellular localization” ha sido realizada en el Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC) en el laboratorio de Regulación espacial de las señales RAS/ERK en cáncer gracias a la Ayuda para contratos predoctorales para la formación de doctores de la agencia estatal consejo superior de investigaciones científicas (BES-2016-077555) y a los proyectos financiados por: MINECO, Ciberonc Isciii, AECC. Durante el presente trabajo Vincenzo Cappitelli ha realizado una estancia predoctoral de 3 meses y medio en el laboratorio del Dr. Adam Hurlstone en la Faculty of Biology, Medicine and Health de la Universidad de Manchester, Reino Unido, gracias a la ayuda para la realización de estancias en otros centros de i+d del ministerio de economía, industria y competitividad (BES-2016-077555)

RAS at the Golgi antagonizes malignant transformation through PTPRκ-mediated inhibition of ERK activation

© The Author(s) 2018.RAS GTPases are frequently mutated in human cancer. H- and NRAS isoforms are distributed over both plasma-membrane and endomembranes, including the Golgi complex, but how this organizational context contributes to cellular transformation is unknown. Here we show that RAS at the Golgi is selectively activated by apoptogenic stimuli and antagonizes cell survival by suppressing ERK activity through the induction of PTPRκ, which targets CRAF for dephosphorylation. Consistently, in contrast to what occurs at the plasma-membrane, RAS at the Golgi cannot induce melanoma in zebrafish. Inactivation of PTPRκ, which occurs frequently in human melanoma, often coincident with TP53 inactivation, accelerates RAS-ERK pathway-driven melanomagenesis in zebrafish. Likewise, tp53 disruption in zebrafish facilitates oncogenesis driven by RAS from the Golgi complex. Thus, RAS oncogenic potential is strictly dependent on its sublocalization, with Golgi complex-located RAS antagonizing tumor development.We are grateful to Drs: Ignacio Rubio, Yardena Samuels, Mariano Barbacid and Javier León for providing reagents; and Alicia Noriega, Sandra Zunzunegui y Victor Campa for technical support. Crespo laboratory is supported by grant SAF-2015 63638R (MINECO/ FEDER, UE); by Red Temática de Investigación Cooperativa sobre el Cáncer (RTICC). RD/12/0036/0033 and by Asociación Española Contra el Cáncer (AECC), grant GCB141423113. Work in the Hurlstone laboratory was unded by a grant from the European Research Council (ERC-2011-StG-282059 PROMINENT). B.C. is supported by a Retos Jóvenes Investigadores grant SAF2015-73364-JIN (AEI/FEDER, UE) and a grant from Fundación Francisco Cobos. X.R.B. is supported by grants from the CastillaLeón Government (BIO/SA01/15, CSI049U16), MINECO (SAF2015-64556-R, RD12/ 0036/0002), Worldwide Cancer Research (14-1248), Ramón Areces Foundation, andAECC (GC16173472GARC). Spanish funding to P.C., B.C., and X.R.B. is partially supported by the European Regional Development Fund

RAS activation at the Golgi Complex prevents tumorigenesis by inducing apoptosis via PTPk-mediated inhibition of ERK activation

Trabajo presentado en el 43th FEBS Congress, celebrado en Praga (República Checa) del 07 al 12 de julio de 2018

Effects of BAMBI deficiency in the development of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies and immune complexes deposition in various organs. Follicular CD4+ T cells play a crucial role in this autoimmune syndrome by activating autoreactive germinal center B cells. The transforming growth factor ß (TGBß) inhibitor BAMBI (Bone Morphogenetic Protein and Activin Membrane-Bound Inhibitor) is known to control the differentiation of CD4+ T lymphocytes into either tolerogenic Tregs or pathogenic Th17 cells. BAMBI absence in mutant mice or its pharmacological inhibition with the B101.37 monoclonal antibody promotes an increase in Treg differentiation and activity and at the same time, a reduction in Th17 cell differentiation, resulting in the inhibition of autoimmune disease development. Based on these findings, in the present study we have analysed the effects of BAMBI deficiency in the development of SLE. We have employed the chronic graft-versus-host disease lupus model induced after the transference of 40-60 × 106 lymphocytes from B6 or B6-BAMBI-KO mice into either Bm12 or Bm12-BAMBI-KO recipients. As reported previously, Bm12 mice receiving lymphocytes from B6 mice produce high levels of circulating IgG anti-DNA and anti-nucleosomal autoantibodies and exhibit linear glomerular IgG deposits in their kidneys. In contrast, both Bm12 mice injected with allogeneic B6-BAMBI-KO lymphocytes and Bm12-BAMBI-KO recipients receiving lymphocytes from B6 donors do not produce significant levels of circulating autoantibodies. Taken together, these results indicate that the absence of BAMBI in either donor or recipient lymphocytes protects mice against the development of SLE

RAS at the Golgi antagonizes malignant transformation through PTPRκ-mediated inhibition of ERK activation

RAS isoforms are associated with the plasma membrane and endomembranes, but how their localization contributes to tumorigenesis is unclear. Here, the authors show that RAS signals from Golgi complex antagonize tumour formation by inducing apoptosis via ERK inhibition