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Jessica M Wilson, Jeremy W Prokop, Ellen Lorimer, Elizabeth Ntantie, Carol L Williams
Two isoforms of the small GTPase Rap1, Rap1A and Rap1B, participate in cell adhesion; Rap1A promotes steady state adhesion, while Rap1B regulates dynamic changes in cell adhesion. These events depend on the prenylation of Rap1, which promotes its membrane localization. Here, we identify previously unsuspected differences in the regulation of prenylation of Rap1A versus Rap1B, due in part to their different phosphorylation-dependent interactions with the chaperone protein SmgGDS-607. Previous studies indicate that activation of Gαs protein-coupled receptors (GPCRs) phosphorylates S-179 and S-180 in the polybasic region (PBR) of Rap1B, which inhibits Rap1B binding to SmgGDS-607 and diminishes Rap1B prenylation and membrane localization...
October 16, 2016: Journal of Molecular Biology
Cheng Wang, Caiyun Wu, Qi Yang, Meng Ding, Jinsha Zhong, Chen-Yu Zhang, Jingping Ge, Junjun Wang, Chunni Zhang
The incidence and mortality rate of renal cell carcinoma (RCC) have been significantly increasing; however, the mechanisms involved in RCC development and progression are unclear. In this study, we found that miR-28-5p was decreased in RCC tumor specimens and several renal carcinoma cell lines. By using a combination of luciferase reporter assays and western blotting, we identified RAP1B, a Ras-related small GTP-binding oncoprotein implicated in a variety of tumors, as a direct target of miR-28-5p in RCC. The RAP1B protein level was increased in RCC tumor specimens and renal carcinoma cell lines, and this was inversely correlated with miR-28-5p expression...
October 7, 2016: Oncotarget
Yazhou Li, Yang Liu, Feiyu Shi, Liang Cheng, Junjun She
Gastric cancer (GC) is the fourth most common malignancy and the second leading cause of cancer mortality around the world. However, the regulatory mechanisms of GC tumorigenesis and cancer cell motility are completely unknown. We investigated the role of a RAS-related protein (Rap1b) in the progression of GC. Our results showed that the expression of Rap1b is aberrantly upregulated in GC tissue samples and human GC cell lines, and the high expression of Rap1b indicated a positive correlation with poor prognosis in patients with GC...
2016: Oncology Research
Haocong Zhang, Yan Wang
BACKGROUND: Spinal cord injury (SCI) is highly related to the devastating sensory and motor dysfunction. METHODS: The GSE45006 gene expression profile dataset was downloaded from Gene Expression Omnibus, which was collected from 24 rats including 20 animals with injured T7 spinal cords using an aneurysm clip impact-compression injury model and killed after 1 day, 3 days, 1 week, 2 weeks, and 8 weeks and four sham-operated rats. Differentially expressed genes (DEGs) between the injured rats at each time point and the sham-operated rats were screened...
2016: Journal of Orthopaedic Surgery and Research
Peter M Benz, Hebatullah Laban, Joana Zink, Lea Günther, Ulrich Walter, Stepan Gambaryan, Karim Dib
BACKGROUND: Vasodilator-Stimulated Phosphoprotein (VASP) is involved in the inhibition of agonist-induced platelet aggregation by cyclic nucleotides and the adhesion of platelets to the vascular wall. αIIbβ3 is the main integrin responsible for platelet activation and Rap1b plays a key role in integrin signalling. We investigated whether VASP is involved in the regulation of Rap1b in platelets since VASP-null platelets exhibit augmented adhesion to endothelial cells in vivo. METHODS: Washed platelets from wild type and VASP-deficient mice were stimulated with thrombin, the purinergic receptors agonist ADP, or the thromboxane A2 receptor agonist U46619 and Rap1b activation was measured using the GST-RalGDS-RBD binding assay...
2016: Cell Communication and Signaling: CCS
Haibo Wang, Xiaokun Han, Colin A Bretz, Silke Becker, Deeksha Gambhir, George W Smith, R Jude Samulski, Erika S Wittchen, Lawrence A Quilliam, Magdalena Chrzanowska-Wodnicka, M Elizabeth Hartnett
To test the hypothesis that increased Rap1a activity specifically in retinal pigment epithelial cells resists choroidal neovascularization (CNV), self-complementary adeno-associated virus 2 (scAAV2) with RPE65-promoter-driven GFP vectors were generated and introduced subretinally into Rap1b-deficient mice. Six-week-old mice that received subretinal control (scAAV2-Con) or constitutively active Rap1a (scAAV2-CARap1a) showed strong GFP at the 5 × 10(8) viral particle/µl dose 5 weeks later without altering retinal morphology or function...
2016: Molecular Therapy. Methods & Clinical Development
S L K Bowers, P R Norden, G E Davis
During capillary network formation, ECs establish interconnecting tubes with defined lumens that reside within vascular guidance tunnels (physical spaces generated during EC tubulogenesis). Pericytes are recruited to EC tubes within these tunnels and capillary basement membrane deposition occurs to facilitate tube maturation. Here, we discuss molecular mechanisms controlling EC tubulogenesis demonstrating the involvement of integrins, MT1-MMP, extracellular matrix, Cdc42, Rac1, Rac2, k-Ras, Rap1b, and key downstream effectors including Pak2, Pak4, IQGAP1, MRCKβ, and Rasip1...
2016: Advances in Pharmacology
Paulina B Szklanna, Martina Foy, Kieran Wynne, Dwayne Byrne, Patricia B Maguire
Proteomic studies have facilitated the identification of proteins associated with the detergent-resistant membrane (DRM) fraction in a variety of cell types. Here, we have undertaken label-free quantitative (LFQ) proteomic profiling of the proteins associated with detergent-resistant plasma and internal membranes from resting and activated platelets. One hundred forty-one proteins were identified and raw data is available via ProteomeXchange with identifier PXD002554. The proteins identified include a myriad of important platelet signaling and trafficking proteins including Rap1b, Src, SNAP-23, syntaxin-11, and members of the previously unattributed Ragulator complex...
September 2016: Proteomics
Young Ou, Gordon Chan, Jeremy Zuo, Jerome B Rattner, Frans A van der Hoorn
The tight, relative positioning of the nucleus and centrosome in mammalian cells is important for the regulation of cell migration. Under pathophysiological conditions, the purinergic A2b receptor can regulate cell motility, but the underlying mechanism remains unknown. Expression of A2b, normally low, is increased in tissues experiencing adverse physiological conditions, including hypoxia and inflammation. ATP is released from such cells. We investigated whether extracellular cues can regulate centrosome-nucleus positioning and cell migration...
July 15, 2016: Journal of Biological Chemistry
Bhavin Shah, Daniela Lutter, Magdalena L Bochenek, Katsuhiro Kato, Yaroslav Tsytsyura, Natalia Glyvuk, Akira Sakakibara, Jürgen Klingauf, Ralf H Adams, Andreas W Püschel
The establishment of a polarized morphology is essential for the development and function of neurons. During the development of the mammalian neocortex, neurons arise in the ventricular zone (VZ) from radial glia cells (RGCs) and leave the VZ to generate the cortical plate (CP). During their migration, newborn neurons first assume a multipolar morphology in the subventricular zone (SVZ) and lower intermediate zone (IZ). Subsequently, they undergo a multi-to-bipolar (MTB) transition to become bipolar in the upper IZ by developing a leading process and a trailing axon...
2016: PloS One
Roman Tatura, Malte Buchholz, Dennis W Dickson, John van Swieten, Catriona McLean, Günter Höglinger, Ulrich Müller
Progressive supranuclear palsy is a sporadic neurodegenerative disorder. Genetic, environmental, and possibly epigenetic factors contribute to disease. In order to better understand the potential role of epigenetic changes in progressive supranuclear palsy, we investigated whether some microRNAs and their target genes are dysregulated. We analyzed expression of 372 well-characterized microRNAs in forebrains of a total of 40 patients and of 40 controls using TaqMan arrays and SYBR Green quantitative real-time PCR...
July 2016: Neurogenetics
Fangyuan Zou, Rurong Mao, Liyan Yang, Shengchao Lin, Kecheng Lei, Yuanhong Zheng, Yue Ding, Peng Zhang, Guoxiang Cai, Xin Liang, Jianwen Liu
miR-139-5p, which has been reported to be underexpressed in several types of cancer, is associated with tumorigenesis by participating in various biological processes via the modulation of different target genes. In the present study, we analyzed mice deficient in miR-139-5p, aiming to investigate its role in intestinal inflammation and colitis-associated colorectal cancer. We show that miR-139-5p knockout (KO) mice are highly susceptible to colitis and colon cancer, accompanied by elevated proliferation and decreased apoptosis, as well as an increased production of inflammatory cytokines, chemokines and tumorigenic factors...
April 2016: FEBS Journal
Michael E Cahill, Rosemary C Bagot, Amy M Gancarz, Deena M Walker, HaoSheng Sun, Zi-Jun Wang, Elizabeth A Heller, Jian Feng, Pamela J Kennedy, Ja Wook Koo, Hannah M Cates, Rachael L Neve, Li Shen, David M Dietz, Eric J Nestler
Dendritic spines are the sites of most excitatory synapses in the CNS, and opposing alterations in the synaptic structure of medium spiny neurons (MSNs) of the nucleus accumbens (NAc), a primary brain reward region, are seen at early versus late time points after cocaine administration. Here we investigate the time-dependent molecular and biochemical processes that regulate this bidirectional synaptic structural plasticity of NAc MSNs and associated changes in cocaine reward in response to chronic cocaine exposure...
February 3, 2016: Neuron
Pieter R Norden, Dae Joong Kim, David M Barry, Ondine B Cleaver, George E Davis
A critical and understudied property of endothelial cells is their ability to form lumens and tube networks. Although considerable information has been obtained concerning these issues, including the role of Cdc42 and Rac1 and their effectors such as Pak2, Pak4, Par6b, and co-regulators such as integrins, MT1-MMP and Par3; many key questions remain that are necessary to elucidate molecular and signaling requirements for this fundamental process. In this work, we identify new small GTPase regulators of EC tubulogenesis including k-Ras, Rac2 and Rap1b that act in conjunction with Cdc42 as well as the key downstream effectors, IQGAP1, MRCKβ, beta-Pix, GIT1, and Rasip1 (which can assemble into multiprotein complexes with key regulators including α2β1 integrin and MT1-MMP)...
2016: PloS One
Magdalena Chrzanowska-Wodnicka, Gilbert C White, Lawrence A Quilliam, Kevin J Whitehead
BACKGROUND: Small GTPase Rap1 has been implicated in a number of basic cellular functions, including cell-cell and cell-matrix adhesion, proliferation and regulation of polarity. Evolutionarily conserved, Rap1 has been studied in model organisms: yeast, Drosophila and mice. Mouse in vivo studies implicate Rap1 in the control of multiple stem cell, leukocyte and vascular cell functions. In vitro, several Rap1 effectors and regulatory mechanisms have been proposed. In particular, Rap1 has been implicated in maintaining epithelial and endothelial cell junction integrity and linked with cerebral cavernous malformations...
2015: PloS One
Marjorie Côte, Camille Fos, Ann J Canonigo-Balancio, Klaus Ley, Stéphane Bécart, Amnon Altman
SLAT (also known as DEF6) promotes T cell activation and differentiation by regulating NFAT-Ca(2+) signaling. However, its role in TCR-mediated inside-out signaling, which induces integrin activation and T cell adhesion, a central process in T cell immunity and inflammation, has not been explored. Here, we show that SLAT is crucial for TCR-induced adhesion to ICAM-1 and affinity maturation of LFA-1 in CD4(+) T cells. Mechanistic studies revealed that SLAT interacts, through its PH domain, with a key component of inside-out signaling, namely the active form of the small GTPase Rap1 (which has two isoforms, Rap1A and Rap1B)...
December 1, 2015: Journal of Cell Science
Marie-Dominique Filippi
The neutrophil transmigration across the blood endothelial cell barrier represents the prerequisite step of innate inflammation. It is well known that neutrophils cross the endothelial barrier by transmigrating at the endothelial cell junction ('paracellular'). However, in vivo and in vitro evidence have clearly demonstrated occurrence of an alternate mode of migration directly through the endothelial cell body ('transcellular'). Despite our knowledge on mechanisms of transendothelial migration, it remains unclear which factors determine distinct modes of migration...
July 2015: Tissue Barriers
Ya Yang, Min Li, Yan Yan, Jia Zhang, Kai Sun, Jing-Kun Qu, Jian-Sheng Wang, Xiao-Yi Duan
Metastasis is the major cause of death among gastric cancer (GC) patients, and altered expression of Ras-related protein RAP1B is associated with cancer development. The present study assessed RAP1B expression ex vivo and the effect of hypoxia‑induced RAP1B overexpression on the promotion of the metastatic potential of GC cells in vitro. Immunohistochemistry was used to detect the expression of RAP1B and hypoxia‑inducible factor-1α (HIF-1α) in 178 GC tissue specimens. GC cell lines were used to assess the effects of hypoxia and RAP1B knockdown with RAP1B small interfering RNA (siRNA)...
November 2015: Oncology Reports
Wenjuan Su, Joseph Wynne, Elaine M Pinheiro, Marianne Strazza, Adam Mor, Emilie Montenont, Jeffrey Berger, David S Paul, Wolfgang Bergmeier, Frank B Gertler, Mark R Philips
Regulation of integrins is critical for lymphocyte adhesion to endothelium and trafficking through secondary lymphoid organs. Inside-out signaling to integrins is mediated by the small GTPase Rap1. Two effectors of Rap1 regulate integrins, RapL and Rap1 interacting adaptor molecule (RIAM). Using mice conditionally deficient in both Rap1a and Rap1b and mice null for RIAM, we show that the Rap1/RIAM module is not required for T- or B-cell development but is essential for efficient adhesion to intercellular adhesion molecule (ICAM) 1 and vascular cell adhesion molecule (VCAM) 1 and for proper trafficking of lymphocytes to secondary lymphoid organs...
December 17, 2015: Blood
Nina Bögershausen, I-Chun Tsai, Esther Pohl, Pelin Özlem Simsek Kiper, Filippo Beleggia, E Ferda Percin, Katharina Keupp, Angela Matchan, Esther Milz, Yasemin Alanay, Hülya Kayserili, Yicheng Liu, Siddharth Banka, Andrea Kranz, Martin Zenker, Dagmar Wieczorek, Nursel Elcioglu, Paolo Prontera, Stanislas Lyonnet, Thomas Meitinger, A Francis Stewart, Dian Donnai, Tim M Strom, Koray Boduroglu, Gökhan Yigit, Yun Li, Nicholas Katsanis, Bernd Wollnik
The genetic disorder Kabuki syndrome (KS) is characterized by developmental delay and congenital anomalies. Dominant mutations in the chromatin regulators lysine (K)-specific methyltransferase 2D (KMT2D) (also known as MLL2) and lysine (K)-specific demethylase 6A (KDM6A) underlie the majority of cases. Although the functions of these chromatin-modifying proteins have been studied extensively, the physiological systems regulated by them are largely unknown. Using whole-exome sequencing, we identified a mutation in RAP1A that was converted to homozygosity as the result of uniparental isodisomy (UPD) in a patient with KS and a de novo, dominant mutation in RAP1B in a second individual with a KS-like phenotype...
September 2015: Journal of Clinical Investigation
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