ERK Signals: Scaffolding Scaffolds?

ERK1/2 MAP Kinases become activated in response to multiple intra- and extra-cellular stimuli through a signaling module composed of sequential tiers of cytoplasmic kinases. Scaffold proteins regulate ERK signals by connecting the different components of the module into a multi-enzymatic complex by which signal amplitude and duration are fine-tuned, and also provide signal fidelity by isolating this complex from external interferences. In addition, scaffold proteins play a central role as spatial regulators of ERKs signals. In this respect, depending on the subcellular localization from which the activating signals emanate, defined scaffolds specify which substrates are amenable to be phosphorylated. Recent evidence has unveiled direct interactions among different scaffold protein species. These scaffold-scaffold macro-complexes could constitute an additional level of regulation for ERK signals and may serve as nodes for the integration of incoming signals and the subsequent diversification of the outgoing signals with respect to substrate engagement.PC lab is supported by grants BFU2011-23807 and SAF-2015 63638R (MINECO/FERDER, UE) from the Spanish Ministry of Economy – Fondos FEDER; by the Red Temática de Investigación Cooperativa en Cáncer (RTICC) (RD/12/0036/0033), Spanish Ministry of Health and by Asociación Española Contra el Cáncer (AECC), grant GCB141423113. BC is a CSIC JAE-Doc program postdoctoral fellow supported by the European Social Fund.Peer reviewedPeer Reviewe

La ruta RAS-ERK como diana antitumoral

La ruta de señalización mediada por las MAP kinasas ERK1 y 2 desempeña un papel esencial en el control de la proliferación, diferenciación y supervivencia celular en condiciones fisiológicas. Los fallos acaecidos en la regulación de dicha ruta, contribuyen significativamente a la transformación celular y están incuestionablemente involucrados en la progresión tumoral, además de en otras patologías. Por esta razón, durante las últimas décadas, esta ruta ha sido el sujeto de intensas investigaciones, con el propósito de identificar componentes susceptibles de ser utilizados como dianas terapéuticas en el tratamiento del cáncer. Aunque en muchos casos los resultados no han sido los esperados, algunas de estas iniciativas han producido compuestos que han logrado progresar a través de las distintas fases preclínicas y clínicas, para incorporarse al arsenal del que actualmente disponemos para combatir el cáncer. En este capítulo, resumimos el estado de las distintas estrategias y de los objetivos que se están llevando a cabo, en el desarrollo de inhibidores contra esta ruta de señalización clave en la patología humana

Immune Checkpoint Inhibitors and RAS–ERK Pathway-Targeted Drugs as Combined Therapy for the Treatment of Melanoma

Metastatic melanoma is a highly immunogenic tumor with very poor survival rates due to immune system escape-mechanisms. Immune checkpoint inhibitors (ICIs) targeting the cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and the programmed death-1 (PD1) receptors, are being used to impede immune evasion. This immunotherapy entails an increment in the overall survival rates. However, melanoma cells respond with evasive molecular mechanisms. ERK cascade inhibitors are also used in metastatic melanoma treatment, with the RAF activity blockade being the main therapeutic approach for such purpose, and in combination with MEK inhibitors improves many parameters of clinical efficacy. Despite their efficacy in inhibiting ERK signaling, the rewiring of the melanoma cell-signaling results in disease relapse, constituting the reinstatement of ERK activation, which is a common cause of some resistance mechanisms. Recent studies revealed that the combination of RAS-ERK pathway inhibitors and ICI therapy present promising advantages for metastatic melanoma treatment. Here, we present a recompilation of the combined therapies clinically evaluated in patients.Funding: PC lab is supported by grant PID2021-126288OB-I00 from the Spanish Ministry of Science (MICIU/AEI/FEDER, UE); PIE 202220E003 from Agencia Estatal Consejo Superior de Investigaciones Científicas; and CIBERONC from the Instituto de Salud Carlos III (ISCIII). AP: Spanish Ministry of Science (PID2020-115605RB-I00), CIBERONC, Junta de Castilla y León (CSI146P20), and the CRIS Cancer Foundation. Our labs receive support from the European Union Regional Development Funding Program (FEDER)

Fast regulation of AP-1 activity through interaction of lamin A/C, ERK1/2, and c-Fos at the nuclear envelope

Sequestration of c-Fos at the nuclear envelope (NE) through interaction with A-type lamins suppresses AP-1–dependent transcription. We show here that c-Fos accumulation within the extraction-resistant nuclear fraction (ERNF) and its interaction with lamin A are reduced and enhanced by gain-of and loss-of ERK1/2 activity, respectively. Moreover, hindering ERK1/2-dependent phosphorylation of c-Fos attenuates its release from the ERNF induced by serum and promotes its interaction with lamin A. Accordingly, serum stimulation rapidly releases preexisting c-Fos from the NE via ERK1/2-dependent phosphorylation, leading to a fast activation of AP-1 before de novo c-Fos synthesis. Moreover, lamin A–null cells exhibit increased AP-1 activity and reduced levels of c-Fos phosphorylation. We also find that active ERK1/2 interacts with lamin A and colocalizes with c-Fos and A-type lamins at the NE. Thus, NE-bound ERK1/2 functions as a molecular switch for rapid mitogen-dependent AP-1 activation through phosphorylation-induced release of preexisting c-Fos from its inhibitory interaction with lamin A/C

Ras subcellular localization inversely regulates thyroid tumor growth and dissemination

RAS mutations are the second most common genetic alteration in thyroid tumors. However, the extent to which they are associated with the most aggressive phenotypes is still controversial. Regarding their malignancy, the majority of RAS mutant tumors are classified as undetermined, which complicates their clinical management and can lead to undesired under-or overtreatment. Using the chick embryo spontaneous metastasis model, we herein demonstrate that the aggressiveness of HRAS-transformed thyroid cells, as determined by the ability to extravasate and metastasize at distant organs, is orchestrated by HRAS subcellular localization. Remarkably, aggressiveness inversely correlates with tumor size. In this respect, we also show that RAS sitespecific capacity to regulate tumor growth and dissemination is dependent on VEGF-B secretion. Furthermore, we have identified the acyl protein thioesterase APT-1 as a determinant of thyroid tumor growth versus dissemination. We show that alterations in APT-1 expression levels can dramatically affect the behavior of thyroid tumors, based on its role as a regulator of HRAS sublocalization at distinct plasma membrane microdomains. In agreement, APT-1 emerges in thyroid cancer clinical samples as a prognostic factor. As such, APT-1 levels could serve as a biomarker that could help in the stratification of HRAS mutant thyroid tumors based on their aggressiveness.PC lab is supported by grant RTI2018-096658B-100 from the Spanish Ministry of Science (MICIU/AEI/FEDER, UE). Santisteban, Riesco and Crespo Laboratories are supported jointly by grants from Asociación Española Contra el Cancer (AECC; GCB141423113) and CIBERONC from the Instituto de Salud Carlos III (ISCIII). PS acknowledges support from: SAF2016-75531-R (MINECO/FEDER, UE); B2017/BMD-3724 Tironet2 (Comunidad de Madrid) and PID2019-105303RB-I00/AEI/10.13039/501100011033 from Ministerio de Ciencia e Innovación (MICIN). B.C is funded by Retos Jóvenes Investigadores grant SAF2015-73364-JIN (MICIU/AEI/FEDER, UE), a PIE grant from Consejo Superior de Investigaciones Científicas (CSIC)- MICIU and the Ramón y Cajal Research Program (MICIU, RYC2018-024004-I)

The small GTP-binding proteins Rac1 and Cdc42regulate the activity of the JNK/SAPK signaling pathway

Summaryc-Jun amino-terminal kinases (JNKs) and mitogen-activatedprotein kinases (MAPKs) are closely related; however, they are independently regulated by a variety of environmental stimuli. Although molecules linking growth factor receptors to MAPKs have been recently identified, little is known about pathways controlling JNK activation. Here, we show that in COS-7 cells, activated Ras effectively stimulates MAPK but poorly induces JNK activity. In contrast, mutationally activated Rac1 and Cdc42 GTPases potently activate JNK without affecting MAPK, and oncogenic guanine nucleotide exchange factors for these Rho-like proteins selectively stimulate JNK activity. Furthermore, expression of inhibitory molecules for Rho-related GTPases and dominant negative mutants of Racl and Cdc42 block JNK activation by oncogenic exchange factors or after induction by inflammatory cytokines and growth factors. Taken together, these findings strongly support a critical role for Racl and Cdc42 in controlling the JNK signaling pathway

Electrical characterization and modeling of 1T-1R RRAM arrays with amorphous and poly-crystalline HfO2

In this work, a comparison between 1T-1R RRAM arrays, manufactured either with amorphous or poly-crystalline Metal–Insulator–Metal cells, is reported in terms of performance, reliability, Set/Reset operations energy requirements, intra-cell and inter-cell variability during 10k endurance cycles and 100k read disturb cycles. The modeling of the 1T-1R RRAM array cells has been performed with two different approaches: (i) a physical model like the Quantum Point Contact (QPC) model was used to find the relationship between the reliability properties observed during the endurance and the read disturb tests with the conductive filament properties; (ii) a compact model to be exploited in circuit simulations tools which models the I–V characteristics of each memory cells technology

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

Scaffold coupling: ERK activation by trans-phosphorylation across different scaffold protein species.

RAS-ERK (extracellular signal-regulated kinase) pathway signals are modulated by scaffold proteins that assemble the components of different kinase tiers into a sequential phosphorylation cascade. In the prevailing model scaffold proteins function as isolated entities, where the flux of phosphorylation events progresses downstream linearly, to achieve ERK phosphorylation. We show that different types of scaffold proteins, specifically KSR1 (kinase suppressor of Ras 1) and IQGAP1 (IQ motif-containing guanosine triphosphatase activating protein 1), can bind to each other, forming a complex whereby phosphorylation reactions occur across both species. MEK (mitogen-activated protein kinase kinase) bound to IQGAP1 can phosphorylate ERK docked at KSR1, a process that we have named trans-phosphorylation. We also reveal that ERK trans-phosphorylation participates in KSR1-regulated adipogenesis, and it also underlies the modest cytotoxicity exhibited by KSR-directed inhibitors. Overall, we identify interactions between scaffold proteins and trans-phosphorylation as an additional level of regulation in the ERK cascade, with broad implications in signaling and the design of scaffold protein-aimed therapeutics

ERK1/2 MAP kinases promote cell cycle entry by rapid, kinase-independent disruption of retinoblastoma–lamin A complexes

When in the nucleus, ERK1/2 dislodges the retinoblastoma protein from lamin A, facilitating its rapid phosphorylation