scholarly journals PIP30/FAM192A is a novel regulator of the nuclear proteasome activator PA28γ

2017 ◽  
Author(s):  
Beata Jonik-Nowak ◽  
Thomas Menneteau ◽  
Didier Fesquet ◽  
Véronique Baldin ◽  
Catherine Bonne-Andrea ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cellular Stress Response ◽  
Cajal Body ◽  
Cajal Bodies ◽  
Central Component ◽  
20S Proteasome ◽  
Independent Manner ◽  
Nuclear Dynamics ◽  
Multiple Functions ◽  
In Cells

ABSTRACTPA28γ is a nuclear activator of the 20S proteasome involved in the regulation of several essential cellular processes, such as cell proliferation, apoptosis, nuclear dynamics and cellular stress response. Unlike the 19S regulator of the proteasome, which specifically recognizes ubiquitylated proteins, PA28γ promotes the degradation of several substrates by the proteasome in an ATP- and ubiquitin-independent manner. However its exact mechanisms of action are unclear and likely to involve additional partners that remain to be identified. Here we report the identification of the first cofactor of PA28γ, PIP30/FAM192A. PIP30 binds directly and specifically via its C-terminal end and in an interaction stabilized by casein kinase 2 phosphorylation to both free and 20S proteasome-associated PA28γ. Its recruitment to proteasome-containing complexes depends on PA28γ and its expression increases the association of PA28γ with the 20S proteasome in cells. Further dissection of its possible roles shows that PIP30 alters PA28γ-dependent activation of peptide degradation by the 20S proteasome in vitro and negatively controls in cells the presence of PA28γ in Cajal Bodies by inhibition of its association with the key Cajal body component coilin. Altogether, our data show that PIP30 deeply affects PA28γ interactions with cellular proteins, including 20S proteasome, demonstrating that it is an important regulator of PA28γ in cells and thus a new player in the control of the multiple functions of the proteasome within the nucleus.Significance StatementThe 20S proteasome is a key actor of the control of protein levels and integrity in cells. To perform its multiple functions, it works with a series of regulators, among which a nuclear complex called PA28γ. In particular, PA28γ participates in the regulation of cell proliferation and nuclear dynamics. We describe here the characterization of a novel protein, PIP30/FAM192A, which binds tightly to PA28γ and favors its interaction with the 20S proteasome while inhibiting its association with coilin, a central component of nuclear Cajal bodies. Thus PIP30/FAM192A critically controls the interactome and consequently the functions of PA28γ, and appears to be a new player in the fine regulation of intracellular proteostasis in the cell nucleus.

scholarly journals PIP30/FAM192A is a novel regulator of the nuclear proteasome activator PA28γ

2018 ◽  
Vol 115 (28) ◽  
pp. E6477-E6486 ◽  
Author(s):  
Beata Jonik-Nowak ◽  
Thomas Menneteau ◽  
Didier Fesquet ◽  
Véronique Baldin ◽  
Catherine Bonne-Andrea ◽  
...  
Keyword(s):  
Cellular Stress Response ◽  
Cajal Body ◽  
20S Proteasome ◽  
Independent Manner ◽  
Nuclear Dynamics ◽  
Cellular Processes ◽  
Important Regulator ◽  
Body Component ◽  
In Cells

PA28γ is a nuclear activator of the 20S proteasome involved in the regulation of several essential cellular processes, such as cell proliferation, apoptosis, nuclear dynamics, and cellular stress response. Unlike the 19S regulator of the proteasome, which specifically recognizes ubiquitylated proteins, PA28γ promotes the degradation of several substrates by the proteasome in an ATP- and ubiquitin-independent manner. However, its exact mechanisms of action are unclear and likely involve additional partners that remain to be identified. Here we report the identification of a cofactor of PA28γ, PIP30/FAM192A. PIP30 binds directly and specifically via its C-terminal end and in an interaction stabilized by casein kinase 2 phosphorylation to both free and 20S proteasome-associated PA28γ. Its recruitment to proteasome-containing complexes depends on PA28γ and its expression increases the association of PA28γ with the 20S proteasome in cells. Further dissection of its possible roles shows that PIP30 alters PA28γ-dependent activation of peptide degradation by the 20S proteasome in vitro and negatively controls in cells the presence of PA28γ in Cajal bodies by inhibition of its association with the key Cajal body component coilin. Taken together, our data show that PIP30 deeply affects PA28γ interactions with cellular proteins, including the 20S proteasome, demonstrating that it is an important regulator of PA28γ in cells and thus a new player in the control of the multiple functions of the proteasome within the nucleus.

scholarly journals Autoregulation of the Mechanistic Target of Rapamycin (mTOR) Complex 2 Integrity Is Controlled by an ATP-dependent Mechanism

2013 ◽  
Vol 288 (38) ◽  
pp. 27019-27030 ◽  
Author(s):  
Chien-Hung Chen ◽  
Vladimir Kiyan ◽  
Assylbek A. Zhylkibayev ◽  
Dubek Kazyken ◽  
Olga Bulgakova ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Kinase Activity ◽  
Glucose Deprivation ◽  
Nutrient Sensing ◽  
Atp Depletion ◽  
Target Of Rapamycin ◽  
Central Component ◽  
Mechanistic Target Of Rapamycin ◽  
Living Organisms ◽  
In Cells

Nutrients are essential for living organisms because they fuel biological processes in cells. Cells monitor nutrient abundance and coordinate a ratio of anabolic and catabolic reactions. Mechanistic target of rapamycin (mTOR) signaling is the essential nutrient-sensing pathway that controls anabolic processes in cells. The central component of this pathway is mTOR, a highly conserved and essential protein kinase that exists in two distinct functional complexes. The nutrient-sensitive mTOR complex 1 (mTORC1) controls cell growth and cell size by phosphorylation of the regulators of protein synthesis S6K1 and 4EBP1, whereas its second complex, mTORC2, regulates cell proliferation by functioning as the regulatory kinase of Akt and other members of the AGC kinase family. The regulation of mTORC2 remains poorly characterized. Our study shows that the cellular ATP balance controls a basal kinase activity of mTORC2 that maintains the integrity of mTORC2 and phosphorylation of Akt on the turn motif Thr-450 site. We found that mTOR stabilizes SIN1 by phosphorylation of its hydrophobic and conserved Ser-260 site to maintain the integrity of mTORC2. The optimal kinase activity of mTORC2 requires a concentration of ATP above 1.2 mm and makes this kinase complex highly sensitive to ATP depletion. We found that not amino acid but glucose deprivation of cells or acute ATP depletion prevented the mTOR-dependent phosphorylation of SIN1 on Ser-260 and Akt on Thr-450. In a low glucose medium, the cells carrying a substitution of SIN1 with its phosphomimetic mutant show an increased rate of cell proliferation related to a higher abundance of mTORC2 and phosphorylation of Akt. Thus, the homeostatic ATP sensor mTOR controls the integrity of mTORC2 and phosphorylation of Akt on the turn motif site.

scholarly journals Assessment and Imaging of Intracellular Magnesium in SaOS-2 Osteosarcoma Cells and Its Role in Proliferation

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1376
Author(s):  
Concettina Cappadone ◽  
Emil Malucelli ◽  
Maddalena Zini ◽  
Giovanna Farruggia ◽  
Giovanna Picone ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Growth ◽  
Magnesium Deficiency ◽  
Acid Synthesis ◽  
Osteosarcoma Cell ◽  
Osteosarcoma Cells ◽  
High Concentration ◽  
Proliferating Cells ◽  
Intracellular Magnesium ◽  
In Cells

Magnesium is an essential nutrient involved in many important processes in living organisms, including protein synthesis, cellular energy production and storage, cell growth and nucleic acid synthesis. In this study, we analysed the effect of magnesium deficiency on the proliferation of SaOS-2 osteosarcoma cells. When quiescent magnesium-starved cells were induced to proliferate by serum addition, the magnesium content was 2–3 times lower in cells maintained in a medium without magnesium compared with cells growing in the presence of the ion. Magnesium depletion inhibited cell cycle progression and caused the inhibition of cell proliferation, which was associated with mTOR hypophosphorylation at Serine 2448. In order to map the intracellular magnesium distribution, an analytical approach using synchrotron-based X-ray techniques was applied. When cell growth was stimulated, magnesium was mainly localized near the plasma membrane in cells maintained in a medium without magnesium. In non-proliferating cells growing in the presence of the ion, high concentration areas inside the cell were observed. These results support the role of magnesium in the control of cell proliferation, suggesting that mTOR may represent an important target for the antiproliferative effect of magnesium. Selective control of magnesium availability could be a useful strategy for inhibiting osteosarcoma cell growth.

scholarly journals Multiple roles of heterogeneous nuclear ribonucleoprotein K during skeletal muscle cell differentiation

2021 ◽  
Author(s):  
Keisuke Hitachi ◽  
Yuri Kiyofuji ◽  
Masashi Nakatani ◽  
Kunihiro Tsuchida
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Protein Complexes ◽  
Myogenic Differentiation ◽  
Cell Physiology ◽  
Transcriptional Level ◽  
Loss Of Function ◽  
Independent Manner ◽  
Multiple Functions

RNA-binding proteins (RBPs) regulate cell physiology via the formation of ribonucleic-protein complexes with coding and non-coding RNAs. RBPs have multiple functions in the same cells; however, the precise mechanism through which their pleiotropic functions are determined remains unknown. In this study, we revealed the multiple inhibitory functions of hnRNPK for myogenic differentiation. We first identified hnRNPK as a lncRNA Myoparr binding protein. Gain- and loss-of-function experiments showed that hnRNPK repressed the expression of myogenin at the transcriptional level via binding to Myoparr. Moreover, hnRNPK repressed the expression of a set of genes coding for aminoacyl-tRNA synthetases in a Myoparr-independent manner. Mechanistically, hnRNPK regulated the eIF2α/Atf4 pathway, one branch of the intrinsic pathways of the endoplasmic reticulum sensors, in differentiating myoblasts. Thus, our findings demonstrate that hnRNPK plays multiple lncRNA-dependent and -independent roles in the inhibition of myogenic differentiation, indicating that the analysis of lncRNA-binding proteins will be useful for elucidating both the physiological functions of lncRNAs and the multiple functions of RBPs.

Heat shock induces mini-Cajal bodies in the Xenopus germinal vesicle

2002 ◽  
Vol 115 (10) ◽  
pp. 2011-2020 ◽  
Author(s):  
Korie E. Handwerger ◽  
Zheng'an Wu ◽  
Christine Murphy ◽  
Joseph G. Gall
Keyword(s):  
Heat Shock ◽  
Germinal Vesicle ◽  
Model System ◽  
Cajal Body ◽  
Self Organization ◽  
Cajal Bodies ◽  
Oocyte Nucleus ◽  
Evolutionarily Conserved ◽  
And Behavior ◽  
Heat Shock Induction

Cajal bodies are evolutionarily conserved nuclear organelles that are believed to play a central role in assembly of RNA transcription and processing complexes. Although knowledge of Cajal body composition and behavior has greatly expanded in recent years, little is known about the molecules and mechanisms that lead to the formation of these organelles in the nucleus. The Xenopus oocyte nucleus or germinal vesicle is an excellent model system for the study of Cajal bodies, because it is easy to manipulate and it contains 50-100 Cajal bodies with diameters up to 10 μm. In this study we show that numerous mini-Cajal bodies (less than 2 μm in diameter) form in the germinal vesicle after oocytes recover from heat shock. The mechanism for heat shock induction of mini-Cajal bodies is independent of U7 snRNA and does not require transcription or import of newly translated proteins from the cytoplasm. We suggest that Cajal bodies originate by self-organization of preformed components, preferentially on the surface of B-snurposomes.

Steroid-induced cell proliferation in vivo is associated with increased c-myc proto-oncogene transcript abundance

Development ◽  
1988 ◽  
Vol 104 (1) ◽  
pp. 87-95
Author(s):  
S.A. Rempel ◽  
R.N. Johnston
Keyword(s):  
Cell Proliferation ◽  
Growth Factors ◽  
Steroid Hormones ◽  
Steroid Hormone ◽  
Normal Liver ◽  
Transcript Abundance ◽  
Chicken Oviduct ◽  
Massive Cell ◽  
In Cells

Enhanced c-myc transcript abundance has been observed in a variety of human malignancies, in normal liver tissue induced to proliferate in vivo by partial hepatectomy and in cells in culture induced to proliferate with the addition of protein hormones and growth factors. Little is known, however, about the expression of cellular proto-oncogenes in cells induced to proliferate in vivo by steroid hormones. Experiments reported here indicate that when cells of the immature chicken oviduct are induced to undergo rapid in vivo proliferation by application of the estrogen hormone 17 beta-estradiol, the onset of this proliferation is associated with a rapid, large, and transient increase in c-myc transcript abundance. When estrogen is administered to chickens in which the oviduct has already differentiated, neither massive cell proliferation nor large increases in c-myc transcript abundance are induced. We conclude that the abundance of c-myc transcripts in vivo correlates well with the degree of cell proliferation induced by steroid hormone.

Mir-Oz Kegulates Osteoblast Apoptosis, Proliferation and Differentiation through Targeted Inhibition of Runx2 in Osteoporosis Running Title: Role and Potential Mechanism of Mir-152 in Osteoporosis

2021 ◽  
Vol 7 (5) ◽  
pp. 4005-4012
Author(s):  
Peng Shi ◽  
Yujie Sun ◽  
Jing Huang ◽  
Lugang Zhou
Keyword(s):  
Cell Proliferation ◽  
Biological Indicator ◽  
Biological Behavior ◽  
Potential Mechanism ◽  
Serum Samples ◽  
Differentiation Markers ◽  
Osteoblast Cell Line ◽  
Auc Value ◽  
Targeted Inhibition ◽  
In Cells

Objective: To explore the role and potential mechanism of miR-152 in osteoporosis. Methods: Fifty-four osteoporotic patients and 54 healthy subjects were recruited from August 2017 to January 2019. Serum samples of the two groups were obtained, and the miR-152 expression in serum was detected and compared. The human osteoblast cell line hFOB1.19 was obtained and miR-152 in cells was increased. The biological behavior changes such as cell proliferation, apoptosis and differentiation were observed by MTT, flow cytometry and detection of osteoblast differentiation markers (ALP, OCN). Results: miR-152 was elevated in osteoporosis patients, and AUC value of serum miR-152 in diagnosing osteoporosis was 0.939. After miR-152 in osteoblasts was elevated, cell proliferation was inhibited, cell apoptosis rate increased, and ALP and OCN content in cells reduced, while increasing cell RUNX2 simultaneously was totally different. Dual luciferase report showed that RUNX2 could be targeted and regulated by miR-152. Conclusion: miR-152 is elevated in serum of osteoporosis patients and can be used as a biological indicator for diagnosing osteoporosis. In addition, miR-152 can inhibit osteoblast proliferation, differentiation and induce apoptosis through negative regulation of RUNX2.

scholarly journals Vaccinia Virus Uses Retromer-Independent Cellular Retrograde Transport Pathways To Facilitate the Wrapping of Intracellular Mature Virions during Virus Morphogenesis

2016 ◽  
Vol 90 (22) ◽  
pp. 10120-10132 ◽  
Author(s):  
Kate Harrison ◽  
Ismar R. Haga ◽  
Tali Pechenick Jowers ◽  
Seema Jasim ◽  
Jean-Christophe Cintrat ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Small Molecule ◽  
Small Molecule Inhibitors ◽  
Clinical Signs ◽  
Retrograde Transport ◽  
Central Component ◽  
Transport Pathways ◽  
Extracellular Virus ◽  
Garp Complex ◽  
In Cells

ABSTRACTPoxviruses, such as vaccinia virus (VACV), undertake a complex cytoplasmic replication cycle which involves morphogenesis through four distinct virion forms and includes a crucial wrapping step whereby intracellular mature virions (IMVs) are wrapped in two additional membranes to form intracellular enveloped virions (IEVs). To determine if cellular retrograde transport pathways are required for this wrapping step, we examined VACV morphogenesis in cells with reduced expression of the tetrameric tethering factor known as the GARP (Golgi-associated retrograde pathway), a central component of retrograde transport. VACV multistep replication was significantly impaired in cells transfected with small interfering RNA targeting the GARP complex and in cells with a mutated GARP complex. Detailed analysis revealed that depletion of the GARP complex resulted in a reduction in the number of IEVs, thereby linking retrograde transport with the wrapping of IMVs. In addition, foci of viral wrapping membrane proteins without an associated internal core accumulated in cells with a mutated GARP complex, suggesting that impaired retrograde transport uncouples nascent IMVs from the IEV membranes at the site of wrapping. Finally, small-molecule inhibitors of retrograde transport strongly suppressed VACV multistep growthin vitroand reduced weight loss and clinical signs in anin vivomurine model of systemic poxviral disease. This work links cellular retrograde transport pathways with the morphogenesis of poxviruses and identifies a panel of novel inhibitors of poxvirus replication.IMPORTANCECellular retrograde transport pathways traffic cargo from endosomes to thetrans-Golgi network and are a key part of the intracellular membrane network. This work reveals that the prototypic poxvirus vaccinia virus (VACV) exploits cellular retrograde transport pathways to facilitate the wrapping of intracellular mature virions and therefore promote the production of extracellular virus. Inhibition of retrograde transport by small-molecule inhibitors reduced the replication of VACV in cell culture and alleviated disease in mice experimentally infected with VACV. This research provides fundamental new knowledge about the wrapping step of poxvirus morphogenesis, furthers our knowledge of the complex cellular retrograde pathways, and identifies a new group of antipoxvirus drugs.

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