scholarly journals A double role of the Gal80 N-terminus in activation of transcription by Gal4p

2020 ◽  
Author(s):  
Annekathrin Reinhardt-Tews ◽  
Rościsław Krutyhołowa ◽  
Christian Günzel ◽  
Sebastian Glatt ◽  
Karin D Breunig
Keyword(s):  
Transcription Activation ◽  
Nuclear Accumulation ◽  
Divergent Evolution ◽  
Nuclear Fraction ◽  
Catalytic Center ◽  
Activation Of Transcription ◽  
Regulatory Module ◽  
N Terminus

ABSTRACTThe yeast galactose switch operated by the Gal4p-Gal80p-Gal3p regulatory module is a textbook model of transcription regulation in eukaryotes. The Gal80 protein inhibits Gal4p-mediated transcription activation by binding to the transcription activation domain. Inhibition is relieved by formation of an alternative Gal80-Gal3 complex. In yeasts lacking a Gal3p ortholog the Gal1 protein combines regulatory and enzymatic activity. The data presented here reveal a so-far unknown role of the Gal80 N-terminus in the mechanism of Gal4p activation. The N-terminus contains an NLS, which is responsible for nuclear accumulation of KlGal80p and galactokinase inhibition in vitro. Herein we propose a model where the N-terminus of KlGal80p reaches into the catalytic center of KlGal1p of the nuclear fraction of KlGal1p triggering dissociation of the KlGal80-KlGal4 complex. We corroborate this model by genetic analyses and structural modelling and provide a rationale for the divergent evolution of the mechanism activating Gal4p.Summary blurbActivation of gene expression by Gal4p in K. lactis requires an element in the N-terminus of KlGal80 that mediates nuclear import, KlGal1 interaction and galactokinase inhibition

scholarly journals A double role of the Gal80 N terminus in activation of transcription by Gal4p

2020 ◽  
Vol 3 (12) ◽  
pp. e202000665
Author(s):  
Annekathrin Reinhardt-Tews ◽  
Rościsław Krutyhołowa ◽  
Christian Günzel ◽  
Constance Roehl ◽  
Sebastian Glatt ◽  
...  
Keyword(s):  
Kluyveromyces Lactis ◽  
Transcription Activation ◽  
Nuclear Accumulation ◽  
Divergent Evolution ◽  
Catalytic Center ◽  
Transcription Activation Domain ◽  
Activation Of Transcription ◽  
Regulatory Module ◽  
N Terminus

The yeast galactose switch operated by the Gal4p–Gal80p–Gal3p regulatory module is a textbook model of transcription regulation in eukaryotes. The Gal80 protein inhibits Gal4p-mediated transcription activation by binding to the transcription activation domain. In Saccharomyces cerevisiae, inhibition is relieved by formation of an alternative Gal80–Gal3 complex. In yeasts lacking a Gal3p ortholog, such as Kluyveromyces lactis, the Gal1 protein (KlGal1p) combines regulatory and enzymatic activity. The data presented here reveal a yet unknown role of the KlGal80 N terminus in the mechanism of Gal4p activation. The N terminus contains an NLS, which is responsible for nuclear accumulation of KlGal80p and KlGal1p and for KlGal80p-mediated galactokinase inhibition. Herein, we present a model where the N terminus of KlGal80p reaches the catalytic center of KlGal1p causing enzyme inhibition in the nucleus and stabilization of the KlGal1–KlGal80p complex. We corroborate this model by genetic analyses and structural modelling and provide a rationale for the divergent evolution of the mechanism activating Gal4p.

scholarly journals RNA Helicase A Regulates the Replication of RNA Viruses

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 361
Author(s):  
Rui-Zhu Shi ◽  
Yuan-Qing Pan ◽  
Li Xing
Keyword(s):  
Virus Replication ◽  
Rna Binding ◽  
Rna Viruses ◽  
Rna Helicase ◽  
Rna Helicase A ◽  
Double Stranded Rna ◽  
Binding Domains ◽  
N Terminus

The RNA helicase A (RHA) is a member of DExH-box helicases and characterized by two double-stranded RNA binding domains at the N-terminus. RHA unwinds double-stranded RNA in vitro and is involved in RNA metabolisms in the cell. RHA is also hijacked by a variety of RNA viruses to facilitate virus replication. Herein, this review will provide an overview of the role of RHA in the replication of RNA viruses.

scholarly journals Oncogenic UBE3C promotes breast cancer progression by activating Wnt/β-catenin signaling

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chen Hang ◽  
Shanojie Zhao ◽  
Tiejun Wang ◽  
Yan Zhang
Keyword(s):  
Breast Cancer ◽  
Cancer Progression ◽  
Nuclear Accumulation ◽  
Migration And Invasion ◽  
Ubiquitin Protein Ligase ◽  
Novel Target ◽  
First Time ◽  
Breast Tissues

Abstract Background Breast cancer (BrCa) is the most common female malignancy worldwide and has the highest morbidity among all cancers in females. Unfortunately, the mechanisms of BrCa growth and metastasis, which lead to a poor prognosis in BrCa patients, have not been well characterized. Methods Immunohistochemistry (IHC) was performed on a BrCa tissue microarray (TMA) containing 80 samples to evaluate ubiquitin protein ligase E3C (UBE3C) expression. In addition, a series of cellular experiments were conducted to reveal the role of UBE3C in BrCa. Results In this research, we identified UBE3C as an oncogenic factor in BrCa growth and metastasis for the first time. UBE3C expression was upregulated in BrCa tissues compared with adjacent breast tissues. BrCa patients with high nuclear UBE3C expression in tumors showed remarkably worse overall survival (OS) than those with low nuclear expression. Knockdown of UBE3C expression in MCF-7 and MDA-MB-453 BrCa cells inhibited cell proliferation, migration and invasion in vitro, while overexpression of UBE3C in these cells exerted the opposite effects. Moreover, UBE3C promoted β-catenin nuclear accumulation, leading to the activation of the Wnt/β-catenin signaling pathway in BrCa cells. Conclusion Collectively, these results imply that UBE3C plays crucial roles in BrCa development and progression and that UBE3C may be a novel target for the prevention and treatment of BrCa.

scholarly journals GCUNC-45 Is a Novel Regulator for the Progesterone Receptor/hsp90 Chaperoning Pathway

2006 ◽  
Vol 26 (5) ◽  
pp. 1722-1730 ◽  
Author(s):  
Ahmed Chadli ◽  
J. Dinny Graham ◽  
M. Greg Abel ◽  
Twila A. Jackson ◽  
David F. Gordon ◽  
...  
Keyword(s):  
Progesterone Receptor ◽  
Atpase Activity ◽  
Binding Site ◽  
Signaling Pathway ◽  
Regulatory Proteins ◽  
N Terminus ◽  
Positive Factor

ABSTRACT The hsp90 chaperoning pathway is a multiprotein system that is required for the production or activation of many cell regulatory proteins, including the progesterone receptor (PR). We report here the identity of GCUNC-45 as a novel modulator of PR chaperoning by hsp90. GCUNC-45, previously implicated in the activities of myosins, can interact in vivo and in vitro with both PR-A and PR-B and with hsp90. Overexpression and knockdown experiments show GCUNC-45 to be a positive factor in promoting PR function in the cell. GCUNC-45 binds to the ATP-binding domain of hsp90 to prevent the activation of its ATPase activity by the cochaperone Aha1. This effect limits PR chaperoning by hsp90, but this can be reversed by FKBP52, a cochaperone that is thought to act later in the pathway. These findings reveal a new cochaperone binding site near the N terminus of hsp90, add insight on the role of FKBP52, and identify GCUNC-45 as a novel regulator of the PR signaling pathway.

scholarly journals Soj Antagonizes Spo0A Activation of Transcription in Bacillus subtilis

2005 ◽  
Vol 187 (7) ◽  
pp. 2532-2536 ◽  
Author(s):  
Brett N. McLeod ◽  
George B. Spiegelman
Keyword(s):  
Bacillus Subtilis ◽  
Transcription Activation ◽  
Wild Type ◽  
Activation Of Transcription ◽  
Family Protein

ABSTRACT The ParA family protein Soj appears to negatively regulate sporulation in Bacillus subtilis by inhibiting transcription from promoters that are activated by phosphorylated Spo0A. We tested in vitro Soj inhibition of Spo0A-independent variants of a promoter that Soj inhibited (PspoIIG). Transcription from the variants was less sensitive to Soj inhibition, suggesting that inhibition of wild-type PspoIIG was linked to transcription activation by Spo0A.

scholarly journals The NEDD8 cycle controlled by NEDP1 upon DNA damage is a regulatory module of the HSP70 ATPase activity

2019 ◽  
Author(s):  
Aymeric P. Bailly ◽  
Aurelien Perrin ◽  
Marina Serrano-Macia ◽  
Chantal Maghames ◽  
Orsolya Leidecker ◽  
...  
Keyword(s):  
Dna Damage ◽  
Atpase Activity ◽  
Apoptosis Induction ◽  
Regulatory Module ◽  
Hsp70 Chaperone ◽  
Response To Stress ◽  
Conjugating Enzymes ◽  
Induced Apoptosis

SummaryUbiquitin and ubiquitin-like chains are finely balanced by the action of conjugating and de-conjugating enzymes. Alterations in this balance trigger signalling events required for the response to stress conditions and are often observed in pathologies. How such changes are detected is not well-understood. We show that upon DNA damage the induction of the de-NEDDylating enzyme NEDP1 restricts the formation of poly-NEDD8 chains, mainly through lysines K11/K48. This promotes APAF1 oligomerisation and apoptosis induction, a step that requires the HSP70 ATPase activity. We found that HSP70 binds to NEDD8 and in vitro, mono-NEDD8 stimulates the ATPase activity of HSP70, counteracted upon poly-NEDDylation. This effect is independent of NEDD8 conjugation onto substrates. The studies identify the HSP70 chaperone as sensor of changes in the NEDD8 cycle, providing mechanistic insights for a cytoplasmic role of NEDD8 in the DNA damage induced apoptosis. They also indicate that the balance between mono- versus poly-NEDDylation is a regulatory module of HSP70 function. The above findings may be important in tumorigenesis, as we find that NEDP1 levels are downregulated in Hepatocellular Carcinoma with concomitant accumulation of NEDD8 conjugates.

scholarly journals Inhibition of TPPP3 attenuates β-catenin/NF-κB/COX-2 signaling in endometrial stromal cells and impairs decidualization

2019 ◽  
Vol 240 (3) ◽  
pp. 417-429 ◽  
Author(s):  
Vinay Shukla ◽  
Jyoti Bala Kaushal ◽  
Pushplata Sankhwar ◽  
Murli Manohar ◽  
Anila Dwivedi
Keyword(s):  
Stromal Cells ◽  
Embryo Implantation ◽  
Nuclear Accumulation ◽  
Decidual Cell ◽  
Endometrial Stromal Cells ◽  
Cox 2 ◽  
Sirna Knockdown

Embryo implantation and decidualization are critical events that occur during early pregnancy. Decidualization is synchronized by the crosstalk of progesterone and the cAMP signaling pathway. Previously, we confirmed the role of TPPP3 during embryo implantation in mice, but the underlying role and mechanism of TPPP3 in decidualization has not yet been understood. The current study was aimed to investigate the role of TPPP3 in decidualization in vivo and in vitro. For in vivo experiments, decidual reaction was artificially induced in the uteri of BALB/c mice. TPPP3 was found to be highly expressed during decidualization, whereas in the uteri receiving TPPP3 siRNA, decidualization was suppressed and the expression of β-catenin and decidual marker prolactin was reduced. In human endometrium, TPPP3 protein was found to be predominantly expressed in the mid-secretory phase (LH+7). In the primary culture of human endometrial stromal cells (hESCs), TPPP3 siRNA knockdown inhibited stromal-to-decidual cell transition and decreased the expression of the decidualization markers prolactin and IGFBP-1. Immunofluorescence and immunoblotting experiments revealed that TPPP3 siRNA knockdown suppressed the expression of β-catenin, NF-κB and COX-2 in hESCs during decidualization. TPPP3 inhibition also decreased NF-kB nuclear accumulation in hESCs and suppressed NF-κB transcriptional promoter activity. COX-2 expression was significantly decreased in the presence of a selective NF-kB inhibitor (QNZ) implicating that NF-kB is involved in COX-2 expression in hESCs undergoing decidualization. TUNEL assay and FACS analysis revealed that TPPP3 knockdown induced apoptosis and caused loss of mitochondrial membrane potential in hESCs. The study suggested that TPPP3 plays a significant role in decidualization and its inhibition leads to the suppression of β-catenin/NF-κB/COX-2 signaling along with the induction of mitochondria-dependent apoptosis.

scholarly journals Exploitation of Microtubule Cytoskeleton and Dynein during Parvoviral Traffic toward the Nucleus

2003 ◽  
Vol 77 (19) ◽  
pp. 10270-10279 ◽  
Author(s):  
Sanna Suikkanen ◽  
Tuula Aaltonen ◽  
Marjukka Nevalainen ◽  
Outi Välilehto ◽  
Laura Lindholm ◽  
...  
Keyword(s):  
Close Contact ◽  
Host Cells ◽  
Nuclear Accumulation ◽  
Viral Capsids ◽  
Cytoplasmic Transport ◽  
Viral Particles ◽  
Endosomal Vesicles ◽  
Model Virus

ABSTRACT Canine parvovirus (CPV), a model virus for the study of parvoviral entry, enters host cells by receptor-mediated endocytosis, escapes from endosomal vesicles to the cytosol, and then replicates in the nucleus. We examined the role of the microtubule (MT)-mediated cytoplasmic trafficking of viral particles toward the nucleus. Immunofluorescence and immunoelectron microscopy showed that capsids were transported through the cytoplasm into the nucleus after cytoplasmic microinjection but that in the presence of MT-depolymerizing agents, viral capsids were unable to reach the nucleus. The nuclear accumulation of capsids was also reduced by microinjection of an anti-dynein antibody. Moreover, electron microscopy and light microscopy experiments demonstrated that viral capsids associate with tubulin and dynein in vitro. Coprecipitation studies indicated that viral capsids interact with dynein. When the cytoplasmic transport process was studied in living cells by microinjecting fluorescently labeled capsids into the cytoplasm of cells containing fluorescent tubulin, capsids were found in close contact with MTs. These results suggest that intact MTs and the motor protein dynein are required for the cytoplasmic transport of CPV capsids and contribute to the accumulation of the capsid in the nucleus.

Mcl-1 Fragment Mcl-1(128–350) Induces Inhibition of Multiple Myeloma Cell Proliferation and Apoptosis Via Both Upregulation of C-Jun as Well as Modulation of Its Transcriptional Activity

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2751-2751
Author(s):  
Klaus Podar ◽  
Jing Zhang ◽  
Alexander Zimmerhackl ◽  
Daniela Barila ◽  
Sonia Vallet ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Proliferation ◽  
Treatment Strategies ◽  
Nuclear Accumulation ◽  
Cell Leukaemia ◽  
Nuclear Fraction ◽  
Dependent Manner ◽  
Drug Induced ◽  
Proliferation And Apoptosis

Abstract Myeloid cell leukaemia-1 (Mcl-1) is an anti- apoptotic member of the Bcl-2 family commonly expressed in multiple myeloma (MM). Drugs (e.g. bortezomib) can induce a 28kD Mcl-1 fragment (Mcl-1Δ128–350) in a caspase- dependent manner, which induces inhibition of MM cell proliferation and apoptosis. Here we sought to delineate molecular sequelae downstream of Mcl-1Δ128–350 which mediate its anti- proliferative and pro-apoptotic effects in MM and other malignant cells. Our results demonstrate that exogenous Mcl-1Δ128–350 induces upregulation and nuclear accumulation of c-Jun, as well as generation of a pro-apoptotic 60kD c-Abl fragment (c-Abl Δ). Bortezomib treatment triggered c-Jun upregulation in Mcl-1wt/wt, but not Mcl-1 null, murine embryonic fibroblasts (MEFs), and neither transfection with exogenous c-Jun nor with exogenous 60kD c-Abl Δ triggered the generation of Mcl-1Δ128–350. Moreover, drug-induced generation of Mcl-1Δ128–350 was not abrogated by specific transient knockdown of c-Jun or c-Abl by small interfering RNA, further supporting the requirement of Mcl-1Δ128–350 for c-Jun upregulation. Our studies also identified mechanisms downstream of upregulated c-Jun which trigger inhibition of MM cell proliferation and apoptosis. Interestingly and similar to c-Jun and c-Abl Δ, Mcl-1Δ128–350 accumulates within the nuclear fraction. Indeed, interaction of Mcl-1Δ128–350 with c-Jun, as well as subsequent enhanced AP-1 reporter activity, demonstrate a direct regulatory role of Mcl-1Δ128–350 in c-Jun- dependent gene transcription. Finally, gene profiles in MM cells transfected with either Mcl-1wt or Mcl-1Δ128–350 identify differentially expressed genes associated with MM cell proliferation, survival and drug resistance. Taken together, these data both delineate the role of Mcl-1 in MM pathogenesis and further support targeting Mcl-1 in novel MM treatment strategies.

scholarly journals N-Terminal α7 Deletion of the Proteasome 20S Core Particle Substitutes for Yeast PI31 Function

2014 ◽  
Vol 35 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Hideki Yashiroda ◽  
Yousuke Toda ◽  
Saori Otsu ◽  
Kenji Takagi ◽  
Tsunehiro Mizushima ◽  
...  
Keyword(s):  
Proteasome Inhibitor ◽  
Core Particle ◽  
Content Type ◽  
Partial Activation ◽  
Gate Opening ◽  
N Terminus ◽  
Substrate Proteins

The proteasome core particle (CP) is a conserved protease complex that is formed by the stacking of two outer α-rings and two inner β-rings. The α-ring is a heteroheptameric ring of subunits α1 to α7 and acts as a gate that restricts entry of substrate proteins into the catalytic cavity formed by the two abutting β-rings. The 31-kDa proteasome inhibitor (PI31) was originally identified as a protein that binds to the CP and inhibits CP activityin vitro, but accumulating evidence indicates that PI31 is required for physiological proteasome activity. To clarify thein vivorole of PI31, we examined theSaccharomyces cerevisiaePI31 ortholog Fub1. Fub1 was essential in a situation where the CP assembly chaperone Pba4 was deleted. The lethality of Δfub1Δpba4was suppressed by deletion of the N terminus of α7 (α7ΔN), which led to the partial activation of the CP. However, deletion of the N terminus of α3, which activates the CP more efficiently than α7ΔN by gate opening, did not suppress Δfub1Δpba4lethality. These results suggest that the α7 N terminus has a role in CP activation different from that of the α3 N terminus and that the role of Fub1 antagonizes a specific function of the α7 N terminus.

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