scholarly journals MDM1 is a microtubule-binding protein that negatively regulates centriole duplication

2015 ◽  
Vol 26 (21) ◽  
pp. 3788-3802 ◽  
Author(s):  
Daniel Van de Mark ◽  
Dong Kong ◽  
Jadranka Loncarek ◽  
Tim Stearns
Keyword(s):  
Binding Protein ◽  
Negative Regulator ◽  
Microtubule Binding ◽  
Centriole Duplication ◽  
Mouse Double Minute ◽  
Multiciliated Cells ◽  
Dividing Cells ◽  
Mouse Cells

Mouse double-minute 1 ( Mdm1) was originally identified as a gene amplified in transformed mouse cells and more recently as being highly up-regulated during differentiation of multiciliated epithelial cells, a specialized cell type having hundreds of centrioles and motile cilia. Here we show that the MDM1 protein localizes to centrioles of dividing cells and differentiating multiciliated cells. 3D-SIM microscopy showed that MDM1 is closely associated with the centriole barrel, likely residing in the centriole lumen. Overexpression of MDM1 suppressed centriole duplication, whereas depletion of MDM1 resulted in an increase in granular material that likely represents early intermediates in centriole formation. We show that MDM1 binds microtubules in vivo and in vitro. We identified a repeat motif in MDM1 that is required for efficient microtubule binding and found that these repeats are also present in CCSAP, another microtubule-binding protein. We propose that MDM1 is a negative regulator of centriole duplication and that its function is mediated through microtubule binding.

Two domains of p80 katanin regulate microtubule severing and spindle pole targeting by p60 katanin

2000 ◽  
Vol 113 (9) ◽  
pp. 1623-1633 ◽  
Author(s):  
K.P. McNally ◽  
O.A. Bazirgan ◽  
F.J. McNally
Keyword(s):  
Mitotic Spindle ◽  
Binding Proteins ◽  
Spindle Pole ◽  
Negative Regulator ◽  
Microtubule Binding ◽  
Microtubule Severing ◽  
Spindle Poles ◽  
Wd40 Domain

The assembly and function of the mitotic spindle requires the activity of a number of microtubule-binding proteins. Some microtubule-binding proteins bind microtubules in vitro but do not co-localize with microtubules in interphase cells. Instead these proteins associate with specific subregions of the mitotic spindle. Katanin, a heterodimeric microtubule-severing ATPase, is found localized at mitotic spindle poles. In this paper we demonstrate that human p60 katanin and the C-terminal domain of human p80 katanin both bind microtubules in vitro. Association of these two proteins results in an increased microtubule affinity and increased microtubule-severing activity in vitro. Association of these subunits in transfected HeLa cells increases microtubule disassembly activity and targeting to spindle poles. The N-terminal WD40 domain of p80 katanin acts as a negative regulator of microtubule disassembly activity and is also required for spindle pole localization, possibly through interactions with another spindle-pole protein. These results support a model in which katanin is targeted to spindle poles through a combination of direct microtubule binding by the p60 subunit and through interactions between the WD40 domain and an unknown protein. We propose that both domains of p80 are essential in precisely regulating katanin's activity in vivo.

scholarly journals TATA-Binding Protein Mutants That Increase Transcription from Enhancerless and Repressed Promoters In Vivo

2000 ◽  
Vol 20 (5) ◽  
pp. 1478-1488 ◽  
Author(s):  
Joseph V. Geisberg ◽  
Kevin Struhl
Keyword(s):  
Binding Protein ◽  
Tata Binding Protein ◽  
Negative Regulator ◽  
Unusual Structure ◽  
Enhancer Element ◽  
Pol Ii ◽  
Activator Proteins ◽  
Pol Iii

ABSTRACT Using a genetic screen, we isolated three TATA-binding protein (TBP) mutants that increase transcription from promoters that are repressed by the Cyc8-Tup1 or Sin3-Rpd3 corepressors or that lack an enhancer element, but not from an equivalently weak promoter with a mutated TATA element. Increased transcription is observed when the TBP mutants are expressed at low levels in the presence of wild-type TBP. These TBP mutants are unable to support cell viability, and they are toxic in strains lacking Rpd3 histone deacetylase or when expressed at higher levels. Although these mutants do not detectably bind TATA elements in vitro, genetic and chromatin immunoprecipitation experiments indicate that they act directly at promoters and do not increase transcription by titration of a negative regulatory factor(s). The TBP mutants are mildly defective for associating with promoters responding to moderate or strong activators; in addition, they are severely defective for RNA polymerase (Pol) III but not Pol I transcription. These results suggest that, with respect to Pol II transcription, the TBP mutants specifically increase expression from core promoters. Biochemical analysis indicates that the TBP mutants are unaffected for TFIID complex formation, dimerization, and interactions with either the general negative regulator NC2 or the N-terminal inhibitory domain of TAF130. We speculate that these TBP mutants have an unusual structure that allows them to preferentially access TATA elements in chromatin templates. These TBP mutants define a criterion by which promoters repressed by Cyc8-Tup1 or Sin3-Rpd3 resemble enhancerless, but not TATA-defective, promoters; hence, they support the idea that these corepressors inhibit the function of activator proteins rather than the Pol II machinery.

scholarly journals The Borrelia hermsii Factor H Binding Protein FhbA Is Not Required for Infectivity in Mice or for Resistance to Human ComplementIn Vitro

2014 ◽  
Vol 82 (8) ◽  
pp. 3324-3332 ◽  
Author(s):  
Lindy M. Fine ◽  
Daniel P. Miller ◽  
Katherine L. Mallory ◽  
Brittney K. Tegels ◽  
Christopher G. Earnhart ◽  
...  
Keyword(s):  
Genetic Manipulation ◽  
Binding Protein ◽  
Factor H ◽  
Negative Regulator ◽  
Human Complement ◽  
Relapsing Fever ◽  
Borrelia Hermsii ◽  
Content Type

ABSTRACTThe primary causative agent of tick-borne relapsing fever in North America isBorrelia hermsii. It has been hypothesized thatB. hermsiievades complement-mediated destruction by binding factor H (FH), a host-derived negative regulator of complement.In vitro,B. hermsiiproduces a single FH binding protein designated FhbA (FH binding protein A). The properties and ligand binding activity of FhbA suggest that it plays multiple roles in pathogenesis. It binds plasminogen and has been identified as a significant target of a B1b B cell-mediated IgM response in mice. FhbA has also been explored as a potential diagnostic antigen forB. hermsiiinfection in humans. The ability to test the hypothesis that FhbA is a critical virulence factorin vivohas been hampered by the lack of well-developed systems for the genetic manipulation of the relapsing fever spirochetes. In this report, we have successfully generated aB. hermsiifhbAdeletion mutant (theB. hermsiiYORΔfhbAstrain) through allelic exchange mutagenesis. Deletion offhbAabolished FH binding by the YORΔfhbAstrain and eliminated cleavage of C3b on the cell surface. However, the YORΔfhbAstrain remained infectious in mice and retained resistance to killingin vitroby human complement. Collectively, these results indicate thatB. hermsiiemploys an FhbA/FH-independent mechanism of complement evasion that allows for resistance to killing by human complement and persistence in mice.

scholarly journals MBD3L1 Is a Transcriptional Repressor That Interacts with Methyl-CpG-binding Protein 2 (MBD2) and Components of the NuRD Complex

2004 ◽  
Vol 279 (50) ◽  
pp. 52456-52464 ◽  
Author(s):  
Chun-Ling Jiang ◽  
Seung-Gi Jin ◽  
Gerd P. Pfeifer
Keyword(s):  
Transcriptional Repression ◽  
Binding Protein ◽  
Transcriptional Repressor ◽  
Binding Domain ◽  
Nurd Complex ◽  
Methylated Dna ◽  
Binding Domains ◽  
Mouse Cells

Methyl-CpG-binding domain proteins 2 and 3 (MBD2 and MBD3) are transcriptional repressors that contain methyl-CpG binding domains and are components of a CpG-methylated DNA binding complex named MeCP1. Methyl-CpG-binding protein 3-like 1 (MBD3L1) is a protein with substantial homology to MBD2 and MBD3, but it lacks the methyl-CpG binding domain. MBD3L1 interacts with MBD2 and MBD3in vitroand in yeast two-hybrid assays. Gel shift experiments with a CpG-methylated DNA probe indicate that recombinant MBD3L1 can supershift an MBD2-methylated DNA complex.In vivo, MBD3L1 associates with and colocalizes with MBD2 but not with MBD3 and is recruited to 5-methylcytosine-rich pericentromeric heterochromatin in mouse cells. In glutathioneS-transferase pull-down assays MBD3L1 is found associated with several known components of the MeCP1·NuRD complex, including HDAC1, HDAC2, MTA2, MBD2, RbAp46, and RbAp48, but MBD3 is not found in the MBD3L1-bound fraction. MBD3L1 enhances transcriptional repression of methylated DNA by MBD2. The data are consistent with a role of MBD3L1 as a methylation-dependent transcriptional repressor that may interchange with MBD3 as an MBD2-interacting component of the NuRD complex. MBD3L1 knockout mice were created and were found to be viable and fertile, indicating that MBD3L1 may not be essential or there is functional redundancy (through MBD3) in this pathway. Overall, this study reveals additional complexities in the mechanisms of transcriptional repression by the MBD family proteins.

scholarly journals Kinetochore-associated Mps1 regulates the strength of kinetochore-microtubule attachments via Ndc80 phosphorylation

2021 ◽  
Author(s):  
Krishna K. Sarangapani ◽  
Lori B. Koch ◽  
Christian R. Nelson ◽  
Charles L. Asbury ◽  
Sue Biggins
Keyword(s):  
Error Correction ◽  
Genetic Interactions ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Additional Mechanism ◽  
Microtubule Binding ◽  
Dividing Cells ◽  
Intrinsic Error

AbstractDividing cells detect and correct erroneous kinetochore-microtubule attachments during mitosis, thereby avoiding chromosome mis-segregation. Most studies of this process have focused on the Aurora B kinase, which phosphorylates microtubule-binding elements specifically at incorrectly attached kinetochores, promoting their release and providing another chance for proper attachments to form. However, growing evidence suggests additional mechanisms, potentially involving Mps1 kinase, that also underlie error correction. Because these mechanisms overlap in vivo, and because both Mps1 and Aurora B function in numerous other vital processes, their contributions to the correction of erroneous kinetochore attachments have been difficult to disentangle. Here we directly examine how Mps1 activity affects kinetochore-microtubule attachments using a reconstitution-based approach that allowed us to separate its effects from Aurora B activity. When endogenous Mps1 that co-purifies with isolated kinetochores is activated in vitro, it weakens their attachments to microtubules via phosphorylation of Ndc80, a major microtubule-binding element of the outer kinetochore. Mps1 phosphorylation of Ndc80 appears to contribute to error correction because phospho-deficient Ndc80 mutants exhibit genetic interactions and segregation defects when combined with mutants in an intrinsic error correction pathway. In addition, Mps1 phosphorylation of Ndc80 is stimulated on kinetochores lacking tension. These data suggest that Mps1 provides an additional mechanism for correcting erroneous kinetochore-microtubule attachments, complementing the well-known activity of Aurora B.

scholarly journals Cold-Inducible RNA-Binding Protein but Not Its Antisense lncRNA Is a Direct Negative Regulator of Angiogenesis In Vitro and In Vivo via Regulation of the 14q32 angiomiRs—Mi-croRNA-329-3p and microRNA-495-3p

2021 ◽  
Vol 22 (23) ◽  
pp. 12678
Author(s):  
Eveline A. C. Goossens ◽  
Licheng Zhang ◽  
Margreet R. de Vries ◽  
J. Wouter Jukema ◽  
Paul H. A. Quax ◽  
...  
Keyword(s):  
Noncoding Rna ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Tube Formation ◽  
Negative Regulator ◽  
Long Term Effects

Inhibition of the 14q32 microRNAs, miR-329-3p and miR-495-3p, improves post-ischemic neovascularization. Cold-inducible RNA-binding protein (CIRBP) facilitates maturation of these microRNAs. We hypothesized that CIRBP deficiency improves post-ischemic angiogenesis via downregulation of 14q32 microRNA expression. We investigated these regulatory mechanisms both in vitro and in vivo. We induced hindlimb ischemia in Cirp−/− and C57Bl/6-J mice, monitored blood flow recovery with laser Doppler perfusion imaging, and assessed neovascularization via immunohistochemistry. Post-ischemic angiogenesis was enhanced in Cirp−/− mice by 34.3% with no effects on arteriogenesis. In vivo at day 7, miR-329-3p and miR-495-3p expression were downregulated in Cirp−/− mice by 40.6% and 36.2%. In HUVECs, CIRBP expression was upregulated under hypothermia, while miR-329-3p and miR-495-3p expression remained unaffected. siRNA-mediated CIRBP knockdown led to the downregulation of CIRBP-splice-variant-1 (CIRBP-SV1), CIRBP antisense long noncoding RNA (lncRNA-CIRBP-AS1), and miR-495-3p with no effects on the expression of CIRBP-SV2-4 or miR-329-3p. siRNA-mediated CIRBP knockdown improved HUVEC migration and tube formation. SiRNA-mediated lncRNA-CIRBP-AS1 knockdown had similar long-term effects. After short incubation times, however, only CIRBP knockdown affected angiogenesis, indicating that the effects of lncRNA-CIRBP-AS1 knockdown were secondary to CIRBP-SV1 downregulation. CIRBP is a negative regulator of angiogenesis in vitro and in vivo and acts, at least in part, through the regulation of miR-329-3p and miR-495-3p.

scholarly journals GAL4 interacts with TATA-binding protein and coactivators.

1995 ◽  
Vol 15 (5) ◽  
pp. 2839-2848 ◽  
Author(s):  
K Melcher ◽  
S A Johnston
Keyword(s):  
Transcriptional Activation ◽  
Binding Protein ◽  
Tata Binding Protein ◽  
Negative Regulator ◽  
Binding Assays ◽  
Amino Acid Peptide ◽  
Eukaryotic Gene ◽  
Transcription In Vitro

A major goal in understanding eukaryotic gene regulation is to identify the target(s) of transcriptional activators. Efforts to date have pointed to various candidates. Here we show that a 34-amino-acid peptide from the carboxy terminus of GAL4 is a strong activation domain (AD) and retains at least four proteins from a crude extract: the negative regulator GAL80, the TATA-binding protein (TBP), and the putative coactivators SUG1 and ADA2. TFIIB was not retained. Concentrating on TBP, we demonstrate in in vitro binding assays that its interaction with the AD is specific, direct, and salt stable up to at least 1.6 M NaCl. The effects of mutations in the GAL4 AD on transcriptional activation in vivo correlate with their affinities to TBP. A point mutation (L114K) in yeast TBP, which has been shown to compromise the mutant protein in both binding to the VP16 AD domain and activated transcription in vitro, reduces the affinity to the GAL4 AD to the same degree as to the VP16 AD. This suggests that these two prototypic activators make similar contacts with TBP.

scholarly journals Kinetochore-bound Mps1 regulates kinetochore–microtubule attachments via Ndc80 phosphorylation

2021 ◽  
Vol 220 (12) ◽  
Author(s):  
Krishna K. Sarangapani ◽  
Lori B. Koch ◽  
Christian R. Nelson ◽  
Charles L. Asbury ◽  
Sue Biggins
Keyword(s):  
Error Correction ◽  
Binding Protein ◽  
Genetic Interactions ◽  
Aurora B ◽  
Aurora B Kinase ◽  
Additional Mechanism ◽  
Microtubule Binding ◽  
Chromosome Missegregation ◽  
Dividing Cells

Dividing cells detect and correct erroneous kinetochore–microtubule attachments during mitosis, thereby avoiding chromosome missegregation. The Aurora B kinase phosphorylates microtubule-binding elements specifically at incorrectly attached kinetochores, promoting their release and providing another chance for proper attachments to form. However, growing evidence suggests that the Mps1 kinase is also required for error correction. Here we directly examine how Mps1 activity affects kinetochore–microtubule attachments using a reconstitution-based approach that allows us to separate its effects from Aurora B activity. When endogenous Mps1 that copurifies with kinetochores is activated in vitro, it weakens their attachments to microtubules via phosphorylation of Ndc80, a major microtubule-binding protein. This phosphorylation contributes to error correction because phospho-deficient Ndc80 mutants exhibit genetic interactions and segregation defects when combined with mutants in other error correction pathways. In addition, Mps1 phosphorylation of Ndc80 is stimulated on kinetochores lacking tension. These data suggest that Mps1 provides an additional mechanism for correcting erroneous kinetochore–microtubule attachments, complementing the well-known activity of Aurora B.

scholarly journals Biochemical and biological properties of cortexillin III, a component of Dictyostelium DGAP1–cortexillin complexes

2014 ◽  
Vol 25 (13) ◽  
pp. 2026-2038 ◽  
Author(s):  
Xiong Liu ◽  
Shi Shu ◽  
Shuhua Yu ◽  
Duck-Yeon Lee ◽  
Grzegorz Piszczek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Leading Edge ◽  
Biological Properties ◽  
Negative Regulator ◽  
Cleavage Furrow ◽  
Motile Cells ◽  
Dividing Cells

Cortexillins I–III are members of the α-actinin/spectrin subfamily of Dictyostelium calponin homology proteins. Unlike recombinant cortexillins I and II, which form homodimers as well as heterodimers in vitro, we find that recombinant cortexillin III is an unstable monomer but forms more stable heterodimers when coexpressed in Escherichia coli with cortexillin I or II. Expressed cortexillin III also forms heterodimers with both cortexillin I and II in vivo, and the heterodimers complex in vivo with DGAP1, a Dictyostelium GAP protein. Binding of cortexillin III to DGAP1 requires the presence of either cortexillin I or II; that is, cortexillin III binds to DGAP1 only as a heterodimer, and the heterodimers form in vivo in the absence of DGAP1. Expressed cortexillin III colocalizes with cortexillins I and II in the cortex of vegetative amoebae, the leading edge of motile cells, and the cleavage furrow of dividing cells. Colocalization of cortexillin III and F-actin may require the heterodimer/DGAP1 complex. Functionally, cortexillin III may be a negative regulator of cell growth, cytokinesis, pinocytosis, and phagocytosis, as all are enhanced in cortexillin III–null cells.

scholarly journals Lentiviral Vectors for Delivery of Gene-Editing Systems Based on CRISPR/Cas: Current State and Perspectives

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1288
Author(s):  
Wendy Dong ◽  
Boris Kantor
Keyword(s):  
Large Scale ◽  
Lentiviral Vector ◽  
Clinical Applications ◽  
Scale Production ◽  
Base Editing ◽  
Epigenome Editing ◽  
Vector Systems ◽  
Dividing Cells

CRISPR/Cas technology has revolutionized the fields of the genome- and epigenome-editing by supplying unparalleled control over genomic sequences and expression. Lentiviral vector (LV) systems are one of the main delivery vehicles for the CRISPR/Cas systems due to (i) its ability to carry bulky and complex transgenes and (ii) sustain robust and long-term expression in a broad range of dividing and non-dividing cells in vitro and in vivo. It is thus reasonable that substantial effort has been allocated towards the development of the improved and optimized LV systems for effective and accurate gene-to-cell transfer of CRISPR/Cas tools. The main effort on that end has been put towards the improvement and optimization of the vector’s expression, development of integrase-deficient lentiviral vector (IDLV), aiming to minimize the risk of oncogenicity, toxicity, and pathogenicity, and enhancing manufacturing protocols for clinical applications required large-scale production. In this review, we will devote attention to (i) the basic biology of lentiviruses, and (ii) recent advances in the development of safer and more efficient CRISPR/Cas vector systems towards their use in preclinical and clinical applications. In addition, we will discuss in detail the recent progress in the repurposing of CRISPR/Cas systems related to base-editing and prime-editing applications.

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