scholarly journals An mDia1-INF2 formin activation cascade facilitated by IQGAP1 regulates stable microtubules in migrating cells

2016 ◽  
Vol 27 (11) ◽  
pp. 1797-1808 ◽  
Author(s):  
Francesca Bartolini ◽  
Laura Andres-Delgado ◽  
Xiaoyi Qu ◽  
Sara Nik ◽  
Nagendran Ramalingam ◽  
...  
Keyword(s):  
Lysophosphatidic Acid ◽  
Dependent Manner ◽  
Common Pathway ◽  
Interacting Protein ◽  
C Terminus ◽  
N Terminus ◽  
In Series ◽  
Activation Cascade ◽  
Unique Mechanism ◽  
Migrating Cells

Multiple formins regulate microtubule (MT) arrays, but whether they function individually or in a common pathway is unknown. Lysophosphatidic acid (LPA) stimulates the formation of stabilized detyrosinated MTs (Glu MTs) in NIH3T3 fibroblasts through RhoA and the formin mDia1. Here we show that another formin, INF2, is necessary for mDia1-mediated induction of Glu MTs and regulation of MT dynamics and that mDia1 can be bypassed by activating INF2. INF2 localized to MTs after LPA treatment in an mDia1-dependent manner, suggesting that mDia1 regulates INF2. Mutants of either formin that disrupt their interaction failed to rescue MT stability in cells depleted of the respective formin, and the mDia1-interacting protein IQGAP1 regulated INF2’s localization to MTs and the induction of Glu MTs by either formin. The N-terminus of IQGAP1 associated with the C-terminus of INF2 directly, suggesting the possibility of a tripartite complex stimulated by LPA. Supporting this, the interaction of mDia1 and INF2 was induced by LPA and dependent on IQGAP1. Our data highlight a unique mechanism of formin action in which mDia1 and INF2 function in series to stabilize MTs and point to IQGAP1 as a scaffold that facilitates the activation of one formin by another.

scholarly journals Copper Induces Cytoplasmic Retention of Fission Yeast Transcription Factor Cuf1

2006 ◽  
Vol 5 (2) ◽  
pp. 277-292 ◽  
Author(s):  
Jude Beaudoin ◽  
Simon Labbé
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Nuclear Localization ◽  
Copper Transport ◽  
Nuclear Localization Sequence ◽  
Binding Motif ◽  
Physical Interaction ◽  
Dependent Manner ◽  
C Terminus ◽  
N Terminus

ABSTRACT Copper homeostasis within the cell is established and preserved by different mechanisms. Changes in gene expression constitute a way of maintaining this homeostasis. In Schizosaccharomyces pombe, the Cuf1 transcription factor is critical for the activation of copper transport gene expression under conditions of copper starvation. However, in the presence of elevated intracellular levels of copper, the mechanism of Cuf1 inactivation to turn off gene expression remains unclear. In this study, we provide evidence that inactivation of copper transport gene expression by Cuf1 is achieved through a copper-dependent, cytosolic retention of Cuf1. We identify a minimal nuclear localization sequence (NLS) between amino acids 11 to 53 within the Cuf1 N terminus. Deletion of this region and specific mutation of the Lys13, Arg16, Arg19, Lys24, Arg28, Lys45, Arg47, Arg50, and Arg53 residues to alanine within this putative NLS is sufficient to abrogate nuclear targeting of Cuf1. Under conditions of copper starvation, Cuf1 resides in the nucleus. However, in the presence of excess copper as well as silver ions, Cuf1 is sequestered in the cytoplasm, a process which requires the putative copper binding motif, 328Cys-X-Cys-X3-Cys-X-Cys-X2-Cys-X2-His342 (designated C-rich), within the C-terminal region of Cuf1. Deletion of this region and mutation of the Cys residues within the C-rich motif result in constitutive nuclear localization of Cuf1. By coexpressing the Cuf1 N terminus with its C terminus in trans and by using a two-hybrid assay, we show that these domains physically interact with each other in a copper-dependent manner. We propose a model wherein copper induces conformational changes in Cuf1 that promote a physical interaction between the Cuf1 N terminus and the C-rich motif in the C terminus that masks the NLS. Cuf1 is thereby sequestered in the cytosol under conditions of copper excess, thereby extinguishing copper transport gene expression.

scholarly journals BVES is a novel interactor of ANO5 and regulates myoblast differentiation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haiwen Li ◽  
Li Xu ◽  
Yandi Gao ◽  
Yuanbojiao Zuo ◽  
Zuocheng Yang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Myoblast Differentiation ◽  
C2c12 Myoblast ◽  
Interacting Proteins ◽  
Cellular Functions ◽  
C2c12 Myoblasts ◽  
Interacting Protein ◽  
C Terminus ◽  
N Terminus ◽  
Labeling Approach

Abstract Background Anoctamin 5 (ANO5) is a membrane protein belonging to the TMEM16/Anoctamin family and its deficiency leads to the development of limb girdle muscular dystrophy R12 (LGMDR12). However, little has been known about the interactome of ANO5 and its cellular functions. Results In this study, we exploited a proximal labeling approach to identify the interacting proteins of ANO5 in C2C12 myoblasts stably expressing ANO5 tagged with BioID2. Mass spectrometry identified 41 unique proteins including BVES and POPDC3 specifically from ANO5-BioID2 samples, but not from BioID2 fused with ANO6 or MG53. The interaction between ANO5 and BVES was further confirmed by co-immunoprecipitation (Co-IP), and the N-terminus of ANO5 mediated the interaction with the C-terminus of BVES. ANO5 and BVES were co-localized in muscle cells and enriched at the endoplasmic reticulum (ER) membrane. Genome editing-mediated ANO5 or BVES disruption significantly suppressed C2C12 myoblast differentiation with little impact on proliferation. Conclusions Taken together, these data suggest that BVES is a novel interacting protein of ANO5, involved in regulation of muscle differentiation.

scholarly journals Dimerization of ubiquilin is dependent upon the central region of the protein: evidence that the monomer, but not the dimer, is involved in binding presenilins

2006 ◽  
Vol 399 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Diana L. Ford ◽  
Mervyn J. Monteiro
Keyword(s):  
Central Region ◽  
Regulatory Mechanism ◽  
Active Form ◽  
Cellular Proteins ◽  
Interacting Protein ◽  
C Terminus ◽  
N Terminus ◽  
The Stability ◽  
Insight Into

Ubiquilin proteins have been shown to interact with a wide variety of other cellular proteins, often regulating the stability and degradation of the interacting protein. Ubiquilin contains a UBL (ubiquitin-like) domain at the N-terminus and a UBA (ubiquitin-associated) domain at the C-terminus, separated by a central region containing Sti1-like repeats. Little is known about regulation of the interaction of ubiquilin with other proteins. In the present study, we show that ubiquilin is capable of forming dimers, and that dimerization requires the central region of ubiquilin, but not its UBL or the UBA domains. Furthermore, we provide evidence suggesting that monomeric ubiquilin is likely to be the active form that is involved in binding presenilin proteins. Our results provide new insight into the regulatory mechanism underlying the interaction of ubiquilin with presenilins.

scholarly journals Rab11-Family Interacting Protein 2 and Myosin Vb Are Required for CXCR2 Recycling and Receptor-mediated Chemotaxis

2004 ◽  
Vol 15 (5) ◽  
pp. 2456-2469 ◽  
Author(s):  
Guo-Huang Fan ◽  
Lynne A. Lapierre ◽  
James R. Goldenring ◽  
Jiqing Sai ◽  
Ann Richmond
Keyword(s):  
Chemokine Receptors ◽  
Fluorescent Protein ◽  
Fine Tuning ◽  
Dependent Manner ◽  
Interacting Protein ◽  
C Terminus ◽  
Myosin Vb ◽  
Ligand Stimulation ◽  
Cellular Responsiveness ◽  
Green Fluorescent

Agonist-stimulated internalization followed by recycling to the cell membrane play an important role in fine-tuning the activity of chemokine receptors. Because the recycling of chemokine receptors is critical for the reestablishment of the cellular responsiveness to ligand, it is crucial to understand the mechanisms underlying the receptor recycling and resensitization. In the present study, we have demonstrated that the chemokine receptor CXCR2 associated with myosin Vb and Rab11-family interacting protein 2 (FIP2) in a ligand-dependent manner. Truncation of the C-terminal domain of the receptor did not affect the association, suggesting that the interactions occur upstream of the C terminus of CXCR2. After ligand stimulation, the internalized CXCR2 colocalized with myosin Vb and Rab11-FIP2 in Rab11a-positive vesicles. The colocalization lasted for ∼2 h, and little colocalization was observed after 4 h of ligand stimulation. CXCR2 also colocalized with myosin Vb tail or Rab11-FIP2 (129–512), the N-terminal–truncated mutants of myosin Vb and Rab11-FIP2, respectively, but in a highly condensed manner. Expression of the enhanced green fluorescent protein-tagged myosin Vb tail significantly retarded the recycling and resensitization of CXCR2. CXCR2 recycling was also reduced by the expression Rab11-FIP2 (129–512). Moreover, expression of the myosin Vb tail reduced CXCR2- and CXCR4-mediated chemotaxis. These data indicate that Rab11-FIP2 and myosin Vb regulate CXCR2 recycling and receptor-mediated chemotaxis and that passage of internalized CXCR2 through Rab11a-positive recycling system is critical for physiological response to a chemokine.

scholarly journals Synovial Sarcoma Translocation (SYT) Encodes a Nuclear Receptor Coactivator

Endocrinology ◽  
2005 ◽  
Vol 146 (9) ◽  
pp. 3892-3899 ◽  
Author(s):  
Toshiharu Iwasaki ◽  
Noriyuki Koibuchi ◽  
William W. Chin
Keyword(s):  
Synovial Sarcoma ◽  
Hormone Receptors ◽  
Rna Binding ◽  
Thyroid Hormone Receptor ◽  
Single Gene ◽  
Binding Motif ◽  
Dependent Manner ◽  
Interacting Protein ◽  
C Terminus ◽  
The Brain

Abstract We previously cloned and characterized a novel RNA-binding motif-containing coactivator, named coactivator activator (CoAA), as a thyroid hormone receptor-binding protein-interacting protein using a Sos-Ras yeast two-hybrid screening system. A database search revealed that CoAA is identical with synovial sarcoma translocation (SYT)-interacting protein. Thus, we hypothesized that SYT could also function as a coactivator. Subsequently, we isolated a cDNA encoding a larger isoform of SYT, SYT-long (SYT-L), from the brain and liver total RNA using RT-PCR. SYT-L possesses an additional 31 amino acids in its C terminus compared with SYT, suggesting that these two SYT isoforms may be expressed from two mRNAs produced by alternative splicing of a transcript from a single gene. By Northern blot analysis, we found that SYT-L mRNA is expressed in several human embryonic tissues, such as the brain, liver, and kidney. However, we could not detect SYT-L in adult tissues. Glutathione-S-transferase pull-down studies showed that SYT binds to the C-terminus of CoAA, but not to the coactivator modulator. Both isoforms of SYT function as transcriptional coactivators of nuclear hormone receptors in a ligand- and dose-dependent manner in CV-1, COS-1, and JEG-3 cells. However, the pattern of transactivation was different between SYT and SYT-L among these cells. SYT synergistically activates transcription with CoAA. In addition, SYT activates transcription through activator protein-1, suggesting that SYT may function as a general coactivator. These results indicate that SYT activates transcription, possibly through CoAA, to interact with the histone acetyltransferase complex.

scholarly journals Identification of SSX2IP/Msd1 as a Wtip-binding partner by targeted proximity biotinylation

2021 ◽  
Author(s):  
Bo Xiang ◽  
Alice H Reis ◽  
Keiji Itoh ◽  
Sergei Y. Sokol
Keyword(s):  
Wilms Tumor ◽  
Cell Junctions ◽  
Basal Bodies ◽  
Dependent Manner ◽  
Apical Constriction ◽  
Interacting Protein ◽  
Biotin Ligase ◽  
Lim Domains ◽  
C Terminus ◽  
Multiciliated Cells

Wilms tumor-1-interacting protein (Wtip) is a LIM-domain-containing adaptor that links cell junctions with actomyosin complexes and modulates actomyosin contractility and ciliogenesis in Xenopus embryos. The Wtip C-terminus with three LIM domains binds binds Shroom3 and modulates Shroom3-induced apical constriction in ectoderm cells. We found that the N-terminal domain localizes to the basal bodies in skin multiciliated cells, but its interacting partners remain largely unknown. Using a novel targeted proximity biotinylation approach with anti-GFP antibody attached to the biotin ligase BirA in the presence of GFP-Wtip-N, we identified SSX2IP as the candidate binding protein. SSX2IP, also known as Msd1 or ADIP, is a centriolar satellite protein that functions as a targeting factor for ciliary membrane proteins. Wtip physically associated with SSX2IP and the two proteins formed mixed spherical aggregates in overexpressing cells in a dose-dependent manner, in a process that resembles phase separation. These results suggest that the interaction between SSX2IP and Wtip is relevant to their functions at the centrosome and basal bodies. The described antibody targeting of biotin ligase should be applicable to other GFP-tagged proteins.

scholarly journals Ribosome-Associated Mba1 Escorts Cox2 from Insertion Machinery to Maturing Assembly Intermediates

2016 ◽  
Vol 36 (22) ◽  
pp. 2782-2793 ◽  
Author(s):  
Isotta Lorenzi ◽  
Silke Oeljeklaus ◽  
Christin Ronsör ◽  
Bettina Bareth ◽  
Bettina Warscheid ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Scaffold Protein ◽  
Intermembrane Space ◽  
Dependent Manner ◽  
Inner Membrane ◽  
Content Type ◽  
Mitochondrial Ribosomes ◽  
C Terminus ◽  
N Terminus ◽  
Conserved Core

The three conserved core subunits of the cytochrome c oxidase are encoded by mitochondria in close to all eukaryotes. The Cox2 subunit spans the inner membrane twice, exposing the N and C termini to the intermembrane space. For this, the N terminus is exported cotranslationally by Oxa1 and subsequently undergoes proteolytic maturation in Saccharomyces cerevisiae . Little is known about the translocation of the C terminus, but Cox18 has been identified to be a critical protein in this process. Here we find that the scaffold protein Cox20, which promotes processing of Cox2, is in complex with the ribosome receptor Mba1 and translating mitochondrial ribosomes in a Cox2-dependent manner. The Mba1-Cox20 complex accumulates when export of the C terminus of Cox2 is blocked by the loss of the Cox18 protein. While Cox20 engages with Cox18, Mba1 is no longer present at this stage. Our analyses indicate that Cox20 associates with nascent Cox2 and Mba1 to promote Cox2 maturation cotranslationally. We suggest that Mba1 stabilizes the Cox20-ribosome complex and supports the handover of Cox2 to the Cox18 tail export machinery.

scholarly journals Determinant of the extracellular location of the N-terminus of human multidrug-resistance-associated protein

2000 ◽  
Vol 348 (3) ◽  
pp. 597-606 ◽  
Author(s):  
Jian-Ting ZHANG
Keyword(s):  
Multidrug Resistance ◽  
Expression System ◽  
Critical Role ◽  
Signal Recognition Particle ◽  
Dependent Manner ◽  
Membrane Translocation ◽  
C Terminus ◽  
N Terminus ◽  
Polytopic Membrane Protein

Multidrug-resistance-associated protein (MRP) is a member of the ATP-binding cassette (ABC) membrane-transport superfamily and is responsible for multidrug resistance in cancer cells. Distinct from other members of the ABC superfamily, MRP has three membrane-spanning domains (MSDs) and the N-terminus is located extracellularly. It has been shown that the first MSD (MSD1) with an extracellular N-terminus is important for MRP function. To address what ensures the generation of this structural organization of MRP and to understand in general the molecular mechanism of membrane folding of polytopic proteins with extracellular N-termini, the biogenesis of MSD1 in human MRP1 was examined using an in vitro expression system. Surprisingly, the second transmembrane segment (TM2) in MSD1 was found to play a critical role in the correct membrane translocation and folding of MSD1 in human MRP1. TM2 not only plays an essential role to ensure the N-terminus-outside/C-terminus-inside orientation of TM1 with an extracellular N-terminus, it can also translocate into membranes post-translationally in a signal-recognition particle and ribosome-dependent manner to provide an additional insurance for correct folding of MSD1 in MRP. These findings suggest that TM2 in a polytopic membrane protein with an extracellular N-terminus may play a critical role in controlling correct membrane translocation and folding of the protein in general.

scholarly journals The Spindle Pole Body Protein Cdc11p Links Sid4p to the Fission Yeast Septation Initiation Network

2002 ◽  
Vol 13 (4) ◽  
pp. 1203-1214 ◽  
Author(s):  
Gregory C. Tomlin ◽  
Jennifer L. Morrell ◽  
Kathleen L. Gould
Keyword(s):  
Spindle Pole Body ◽  
Direct Interaction ◽  
Spindle Pole ◽  
Small Gtpase ◽  
Dependent Manner ◽  
Body Protein ◽  
Pole Body ◽  
C Terminus ◽  
N Terminus ◽  
Septation Initiation Network

The Schizosaccharomyces pombe septation initiation network (SIN) signals the onset of cell division from the spindle pole body (SPB) and is regulated by the small GTPase Spg1p. The localization of SIN components including Spg1p to the SPB is required for cytokinesis and is dependent on Sid4p, a constitutive resident of SPBs. However, a direct interaction between Sid4p and other members of the SIN has not been detected. To understand how Sid4p is linked to other SIN components, we have begun to characterize an S. pombe homolog of the Saccharomyces cerevisiaeSPB protein Nud1p. We have determined that this S. pombeNud1p homolog corresponds to Cdc11p, a previously uncharacterized SIN element. We report that Cdc11p is present constitutively at SPBs and that its function appears to be required for the localization of all other SIN components to SPBs with the exception of Sid4p. The Cdc11p C terminus localizes the protein to SPBs in a Sid4p-dependent manner, and we demonstrate a direct Cdc11p-Sid4p interaction. The N-terminus of Cdc11p is required for Spg1p binding to SPBs. Our studies indicate that Cdc11p provides a physical link between Sid4p and the Spg1p signaling pathway.

CSIG-07. ACTIVATION OF THE ADHESION G PROTEIN-COUPLED RECEPTOR GPR133 BY ANTIBODIES AGAINST THE N-TERMINUS

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi34-vi34
Author(s):  
Gabriele Stephan ◽  
Joshua Frenster ◽  
Niklas Ravn-Boess ◽  
Devin Bready ◽  
Jordan Wilcox ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Receptor Activation ◽  
Cell Culture Supernatant ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Terminal Fragment ◽  
C Terminus ◽  
N Terminus ◽  
G Protein Coupled

Abstract We recently demonstrated that GPR133 (ADGRD1), a member of the adhesion G protein-coupled receptor (aGPCR) family, is necessary for growth of glioblastoma (GBM) and is de novo expressed in GBM relative to normal brain tissue. We therefore postulate that GPR133 represents a novel target in GBM, which merits development of therapeutics. Like most aGPCRs, GPR133 is characterized by an intracellular C-terminus, 7 plasma membrane-spanning α-helices and a large extracellular N-terminus. The N-terminus possesses a conserved GPCR autoproteolysis-inducing (GAIN) domain that catalyzes cleavage at a GPCR proteolysis site (GPS), resulting in a C-terminal fragment (CTF) and an N-terminal fragment (NTF). We showed that dissociation of the cleaved NTF and CTF at the plasma membrane increases canonical signaling of GPR133, which is mediated by coupling to Gs and increase in cytosolic cAMP. Toward characterizing the effect of biologics on GPR133 function, we overexpressed wild-type or mutant forms of GPR133 in HEK293T cells and patient-derived GBM cells lines. Treatment of these cells with antibodies specifically targeting the NTF of GPR133 increased receptor activation in a dose-dependent manner. No effects were elicited with an antibody against the receptor’s intracellular C-terminus. Interestingly, cells overexpressing a cleavage-deficient mutant GPR133 (H543R) did not respond to antibody stimulation, suggesting that the effect is cleavage-dependent. Following antibody treatment, co-purification of the GPR133 NTF and the N-terminal antibody from the cell culture supernatant indicated the formation of antibody-NTF complexes. Analysis of these complexes suggested that antibody binding stimulated the dissociation of the NTF from the CTF. However, the increased flexibility of the GAIN domain and NTF after cleavage, independently of dissociation, may also endow the receptor with responsiveness to the effects of the antibodies. These data constitute a proof-of-concept paradigm of modulation of GPR133 function with antibodies. This work provides rationale for pursuing development of biologics targeting GPR133 in GBM.

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