scholarly journals Arginine Methylation of hnRNPK Inhibits the DDX3-hnRNPK Interaction to Play an Anti-Apoptosis Role in Osteosarcoma Cells

2021 ◽  
Vol 22 (18) ◽  
pp. 9764
Author(s):  
Chiao-Che Chen ◽  
Jen-Hao Yang ◽  
Shu-Ling Fu ◽  
Wey-Jinq Lin ◽  
Chao-Hsiung Lin
Keyword(s):  
Dna Damage ◽  
Arginine Methylation ◽  
Osteosarcoma Cells ◽  
Atp Binding Site ◽  
C Terminus ◽  
Defective Mutant ◽  
Cell Processes ◽  
And Migration ◽  
Nuclear Ribonucleoprotein

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA/DNA binding protein involved in diverse cell processes; it is also a p53 coregulator that initiates apoptosis under DNA damage conditions. However, the upregulation of hnRNPK is correlated with cancer transformation, progression, and migration, whereas the regulatory role of hnRNPK in cancer malignancy remains unclear. We previously showed that arginine methylation of hnRNPK attenuated the apoptosis of U2OS osteosarcoma cells under DNA damage conditions, whereas the replacement of endogenous hnRNPK with a methylation-defective mutant inversely enhanced apoptosis. The present study further revealed that an RNA helicase, DDX3, whose C-terminus preferentially binds to the unmethylated hnRNPK and could promote such apoptotic enhancement. Moreover, C-terminus-truncated DDX3 induced significantly less apoptosis than full-length DDX3. Notably, we also identified a small molecule that docks at the ATP-binding site of DDX3, promotes the DDX3-hnRNPK interaction, and induces further apoptosis. Overall, we have shown that the arginine methylation of hnRNPK suppresses the apoptosis of U2OS cells via interfering with DDX3–hnRNPK interaction. On the other hand, DDX3–hnRNPK interaction with a proapoptotic role may serve as a target for promoting apoptosis in osteosarcoma cells.

scholarly journals Arginine methylation of hnRNPK negatively modulates apoptosis upon DNA damage through local regulation of phosphorylation

2014 ◽  
Vol 42 (15) ◽  
pp. 9908-9924 ◽  
Author(s):  
Jen-Hao Yang ◽  
Yi-Ying Chiou ◽  
Shu-Ling Fu ◽  
I-Yun Shih ◽  
Tsai-Hsuan Weng ◽  
...  
Keyword(s):  
Dna Damage ◽  
Rna Processing ◽  
Tumor Development ◽  
Arginine Methylation ◽  
Wild Type ◽  
Post Translational Modifications ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Damage Response ◽  
Nuclear Ribonucleoprotein

Abstract Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA/DNA-binding protein involved in chromatin remodeling, RNA processing and the DNA damage response. In addition, increased hnRNPK expression has been associated with tumor development and progression. A variety of post-translational modifications of hnRNPK have been identified and shown to regulate hnRNPK function, including phosphorylation, ubiquitination, sumoylation and methylation. However, the functional significance of hnRNPK arginine methylation remains unclear. In the present study, we demonstrated that the methylation of two essential arginines, Arg296 and Arg299, on hnRNPK inhibited a nearby Ser302 phosphorylation that was mediated through the pro-apoptotic kinase PKCδ. Notably, the engineered U2OS cells carrying an Arg296/Arg299 methylation-defective hnRNPK mutant exhibited increased apoptosis upon DNA damage. While such elevated apoptosis can be diminished through addition with wild-type hnRNPK, we further demonstrated that this increased apoptosis occurred through both intrinsic and extrinsic pathways and was p53 independent, at least in part. Here, we provide the first evidence that the arginine methylation of hnRNPK negatively regulates cell apoptosis through PKCδ-mediated signaling during DNA damage, which is essential for the anti-apoptotic role of hnRNPK in apoptosis and the evasion of apoptosis in cancer cells.

scholarly journals The Main Role of Srs2 in DNA Repair Depends on Its Helicase Activity, Rather than on Its Interactions with PCNA or Rad51

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Alex Bronstein ◽  
Lihi Gershon ◽  
Gilad Grinberg ◽  
Elisa Alonso-Perez ◽  
Martin Kupiec
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Genome Stability ◽  
Dna Helicase ◽  
Main Role ◽  
Helicase Domain ◽  
Helicase Activity ◽  
C Terminus ◽  
Srs2 Helicase

ABSTRACTHomologous recombination (HR) is a mechanism that repairs a variety of DNA lesions. Under certain circumstances, however, HR can generate intermediates that can interfere with other cellular processes such as DNA transcription or replication. Cells have therefore developed pathways that abolish undesirable HR intermediates. TheSaccharomyces cerevisiaeyeast Srs2 helicase has a major role in one of these pathways. Srs2 also works during DNA replication and interacts with the clamp PCNA. The relative importance of Srs2’s helicase activity, Rad51 removal function, and PCNA interaction in genome stability remains unclear. We created a newSRS2allele [srs2(1-850)] that lacks the whole C terminus, containing the interaction site for Rad51 and PCNA and interactions with many other proteins. Thus, the new allele encodes an Srs2 protein bearing only the activity of the DNA helicase. We find that the interactions of Srs2 with Rad51 and PCNA are dispensable for the main role of Srs2 in the repair of DNA damage in vegetative cells and for proper completion of meiosis. On the other hand, it has been shown that in cells impaired for the DNA damage tolerance (DDT) pathways, Srs2 generates toxic intermediates that lead to DNA damage sensitivity; we show that this negative Srs2 activity requires the C terminus of Srs2. Dissection of the genetic interactions of thesrs2(1-850) allele suggest a role for Srs2’s helicase activity in sister chromatid cohesion. Our results also indicate that Srs2’s function becomes more central in diploid cells.IMPORTANCEHomologous recombination (HR) is a key mechanism that repairs damaged DNA. However, this process has to be tightly regulated; failure to regulate it can lead to genome instability. The Srs2 helicase is considered a regulator of HR; it was shown to be able to evict the recombinase Rad51 from DNA. Cells lacking Srs2 exhibit sensitivity to DNA-damaging agents, and in some cases, they display defects in DNA replication. The relative roles of the helicase and Rad51 removal activities of Srs2 in genome stability remain unclear. To address this question, we created a new Srs2 mutant which has only the DNA helicase domain. Our study shows that only the DNA helicase domain is needed to deal with DNA damage and assist in DNA replication during vegetative growth and in meiosis. Thus, our findings shift the view on the role of Srs2 in the maintenance of genome integrity.

scholarly journals TopBP1 and ATR Colocalization at Meiotic Chromosomes: Role of TopBP1/Cut5 in the Meiotic Recombination Checkpoint

2004 ◽  
Vol 15 (4) ◽  
pp. 1568-1579 ◽  
Author(s):  
David Perera ◽  
Livia Perez-Hidalgo ◽  
Peter B. Moens ◽  
Kaarina Reini ◽  
Nicholas Lakin ◽  
...  
Keyword(s):  
Dna Damage ◽  
Meiotic Recombination ◽  
Early Prophase ◽  
Dna Damage Checkpoint ◽  
Dna Double Strand Breaks ◽  
Direct Role ◽  
Meiotic Chromosomes ◽  
Defective Mutant ◽  
Recombination Checkpoint

Mammalian TopBP1 is a BRCT domain–containing protein whose function in mitotic cells is linked to replication and DNA damage checkpoint. Here, we study its possible role during meiosis in mice. TopBP1 foci are abundant during early prophase I and localize mainly to histone γ-H2AX–positive domains, where DNA double–strand breaks (required to initiate recombination) occur. Strikingly, TopBP1 showed a pattern almost identical to that of ATR, a PI3K-like kinase involved in mitotic DNA damage checkpoint. In the synapsis-defective Fkbp6-/- mouse, TopBP1 heavily stains unsynapsed regions of chromosomes. We also tested whether Schizosaccharomyces pombe Cut5 (the TopBP1 homologue) plays a role in the meiotic recombination checkpoint, like spRad3, the ATR homologue. Indeed, we found that a cut5 mutation suppresses the checkpoint-dependent meiotic delay of a meiotic recombination defective mutant, indicating a direct role of the Cut5 protein in the meiotic checkpoint. Our findings suggest that ATR and TopBP1 monitor meiotic recombination and are required for activation of the meiotic recombination checkpoint.

scholarly journals Role of Phosphodiesterase2A in Proliferation and Migration of Human Osteosarcoma Cells

2019 ◽  
Vol 39 (11) ◽  
pp. 6057-6062
Author(s):  
TAKU MURATA ◽  
KASUMI SHIMIZU ◽  
KAZUTO KUROHARA ◽  
AKIRA TOMEOKU ◽  
GAKU KOIZUMI ◽  
...  
Keyword(s):  
Osteosarcoma Cells ◽  
Human Osteosarcoma ◽  
Human Osteosarcoma Cells ◽  
And Migration ◽  
Proliferation And Migration

scholarly journals CK2α/CSNK2A1 Induces Resistance to Doxorubicin Through SIRT6 Mediated Activation of the DNA Damage Repair Pathway

2021 ◽  
Author(s):  
Usama Khamis Hussein ◽  
Asmaa Gamal Ahmed ◽  
Yiping Song ◽  
See-Hyoung Park ◽  
Kyoung Min Kim ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cancer Progression ◽  
Dna Damage Repair ◽  
Repair Pathway ◽  
Osteosarcoma Cells ◽  
Cytotoxic Effects ◽  
Damage Repair ◽  
Anti Cancer ◽  
Resistance To Doxorubicin

Abstract BackgroundCK2α/CSNK2A1 is involved in cancer progression by phosphorylating various signaling molecules. Considering the role of CSNK2A1 in cancer progression and phosphorylation of SIRT6 and the role of SIRT6 in chemoresistance through the DNA damage repair pathway, CSNK2A1 and SIRT6 might be involved in resistance to the conventional anti-cancer therapies.MethodsWe evaluated the expression of CSNK2A1 in the 37 osteosarcoma patients and investigated the effects of CSNK2A1 and phosphorylation of SIRT6 on Ser338 on the resistance to the anti-cancer effects of doxorubicin. Results Higher expression of CSNK2A1 predicted shorter overall survival and relapse-free survival in both general osteosarcoma patients and sub-population of patients who received postoperative chemotherapies. U2OS and KHOS/NP osteosarcoma cells with induced overexpression of CSNK2A1 were resistant to cytotoxic effects of doxorubicin, and knock-down of CSNK2A1 potentiated the cytotoxic effects of doxorubicin. CSNK2A1 overexpression-mediated resistance to doxorubicin was associated with SIRT6 phosphorylation and induction of the DNA damage repair pathway molecules ATM and Chk2. CSNK2A1 and SIRT6 mediated resistance to doxorubicin in vivo was attenuated via mutation of SIRT6 at the Ser338 phosphorylation site. Emodin, a CSNK2A1 inhibitor, potentiated the cytotoxic effects of doxorubicin in osteosarcoma cells in vitro. ConclusionsThis study demonstrates that the expression of CSNK2A1 might be used as a prognostic indicator of osteosarcoma. In addition, it suggests that CSNK2A1 induces resistance to doxorubicin through phosphorylation of SIRT6-mediated activation of the DNA damage repair pathway. Therefore, blocking the CSNK2A1-SIRT6-DNA damage repair pathway might be a new therapeutic stratagem for the poor prognostic subgroup of osteosarcomas with high expression of CSNK2A1.

scholarly journals Interfering with pak4 Protein Expression Affects Osteosarcoma Cell Proliferation and Migration

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yuxin Fu ◽  
Lun Fang ◽  
Qipu Yin ◽  
Qi Wu ◽  
Wei Sui ◽  
...  
Keyword(s):  
Protein Expression ◽  
Osteosarcoma Cell ◽  
Mrna Levels ◽  
Osteosarcoma Cells ◽  
Migration Ability ◽  
M Phase ◽  
Underlying Mechanisms ◽  
And Migration ◽  
Proliferation And Migration

Purpose. A number of studies have discovered various roles of PAK4 in human tumors, including osteosarcoma. However, the exact role of PAK4 in osteosarcoma and its mechanism have yet to be determined. Therefore, this study focused on interrogating the PAK4 effect on the proliferation and migration ability of osteosarcoma and its underlying mechanisms. Materials and Methods. Western blot and QRT-PCR were utilized to quantify the PAK4 relative protein and mRNA levels. To measure cellular viability and mobility, the MTT and wound-healing assays were preferred. Results. With the adenovirus-mediated overexpression of PAK4, the proliferation and migration of U2-OS and MG-63 osteosarcoma cells were stimulated. Furthermore, a liposome-mediated knockout of PAK4 will inhibit osteosarcoma cells from proliferating. In terms of mechanism, we observed the positive correlation of PAK4 expression with expression of P21, CyclinD1, CyclinE1, CDK2, and CDK6, which drives G0/G1 to the G2/M phase transition. PAK4 can also activate Erk expression in OS cells and induce EMT. Conclusion. Interfering with PAK4 protein expression has been shown to affect osteosarcoma proliferation and migration.

scholarly journals RFWD2 Knockdown as a Blocker to Reverse the Oncogenic Role of TRIB2 in Lung Adenocarcinoma

2021 ◽  
Vol 11 ◽  
Author(s):  
Ruimin Hao ◽  
Jinxia Hu ◽  
Yuemei Liu ◽  
Dongmin Liang ◽  
Yan-Mei Li ◽  
...  
Keyword(s):  
Cancer Cell ◽  
Cancer Cell Proliferation ◽  
Cancer Cell Growth ◽  
Specific Domain ◽  
Cancer Breast ◽  
C Terminus ◽  
And Migration

RFWD2, an E3 ubiquitin ligase, is overexpressed in numerous human cancers, including leukemia, lung cancer, breast cancer, renal cell carcinoma, and colorectal cancer. The roles of RFWD2 in cancer are related to the targeting of its substrates for ubiquitination and degradation. This study aimed to investigate the role of TRIB2 in relation to the regulation of protein degradation through RFWD2. inBio Discover™ results demonstrated that TRIB2 can perform its functions by interacting with RFWD2 or other factors. TRIB2 can interact with and regulate RFWD2, which further attends the proteasome-mediated degradation of the RFWD2 substrate p-IκB-α. TRIB2 colocalizes with RFWD2-related IκB-α to form a ternary complex and further affects the IκB-α degradation by regulating its phosphorylation. Specific domain analysis showed that TRIB2 may bind to RFWD2 via its C-terminus, whereas it binds to IκB via its pseudokinase domain. TRIB2 acts as an oncogene and promotes cancer cell proliferation and migration, whereas RFWD2 knockdown reversed the role of TRIB2 in promoting cancer cell growth and colony formation in vitro and in vivo. In summary, this study reveals that TRIB2 promotes the progression of cancer by affecting the proteasome-mediated degradation of proteins through the interaction with RFWD2.

scholarly journals Role of the C Terminus of Mec1 Checkpoint Kinase in Its Localization to Sites of DNA Damage

2005 ◽  
Vol 16 (11) ◽  
pp. 5227-5235 ◽  
Author(s):  
Daisuke Nakada ◽  
Yukinori Hirano ◽  
Yuya Tanaka ◽  
Katsunori Sugimoto
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
Protein A ◽  
Dna Lesions ◽  
Ataxia Telangiectasia Mutated ◽  
Dna Damage Signaling ◽  
C Terminus ◽  
Two Hybrid ◽  
Substitution Mutation

The large protein kinases, ataxia-telangiectasia mutated (ATM) and ATM-Rad3-related (ATR), coordinate the cellular response to DNA damage. In budding yeast, ATR homologue Mec1 plays a central role in DNA damage signaling. Mec1 interacts physically with Ddc2 and functions in the form of the Mec1–Ddc2 complex. To identify proteins interacting with the Mec1–Ddc2 complex, we performed a modified two-hybrid screen and isolated RFA1 and RFA2, genes that encode subunits of replication protein A (RPA). Using the two-hybrid system, we found that the extreme C-terminal region of Mec1 is critical for RPA binding. The C-terminal substitution mutation does not affect the Mec1–Ddc2 complex formation, but it does impair the interaction of Mec1 and Ddc2 with RPA as well as their association with DNA lesions. The C-terminal mutation also decreases Mec1 kinase activity. However, the Mec1 kinase-defect by itself does not perturb Mec1 association with sites of DNA damage. We also found that Mec1 and Ddc2 associate with sites of DNA damage in an interdependent manner. Our findings support the model in which Mec1 and Ddc2 localize to sites of DNA damage by interacting with RPA in the form of the Mec1–Ddc2 complex.

scholarly journals How the extracellular matrix shapes neural development

Open Biology ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 180216 ◽  
Author(s):  
Katherine R. Long ◽  
Wieland B. Huttner
Keyword(s):  
Extracellular Matrix ◽  
Neural Development ◽  
Cell Shape ◽  
Individual Cell ◽  
Proper Function ◽  
Open Questions ◽  
Neural Tissues ◽  
Cell Processes ◽  
And Migration

During development, both cells and tissues must acquire the correct shape to allow their proper function. This is especially relevant in the nervous system, where the shape of individual cell processes, such as the axons and dendrites, and the shape of entire tissues, such as the folding of the neocortex, are highly specialized. While many aspects of neural development have been uncovered, there are still several open questions concerning the mechanisms governing cell and tissue shape. In this review, we discuss the role of the extracellular matrix (ECM) in these processes. In particular, we consider how the ECM regulates cell shape, proliferation, differentiation and migration, and more recent work highlighting a key role of ECM in the morphogenesis of neural tissues.

scholarly journals MDMX is essential for the regulation of p53 protein levels in the absence of a functional MDM2 C-terminal tail

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jack D. Sanford ◽  
Jing Yang ◽  
Jing Han ◽  
Laura A. Tollini ◽  
Aiwen Jin ◽  
...  
Keyword(s):  
Dna Damage ◽  
Protein Expression ◽  
P53 Protein ◽  
Critical Role ◽  
E3 Ligase ◽  
Mouse Embryonic Fibroblast ◽  
Protein Levels ◽  
P53 Protein Expression ◽  
C Terminus

Abstract Background MDM2 is an E3 ubiquitin ligase that is able to ubiquitinate p53, targeting it for proteasomal degradation. Its homologue MDMX does not have innate E3 activity, but is able to dimerize with MDM2. Although mouse models have demonstrated both MDM2 and MDMX are individually essential for p53 regulation, the significance of MDM2-MDMX heterodimerization is only partially understood and sometimes controversial. MDM2C462A mice, where the C462A mutation abolishes MDM2 E3 ligase activity as well as its ability to dimerize with MDMX, die during embryogenesis. In contrast, the MDM2Y487A mice, where the Y487A mutation at MDM2 C-terminus significantly reduces its E3 ligase activity without disrupting MDM2-MDMX binding, survive normally even though p53 is expressed to high levels. This indicates that the MDM2-MDMX heterodimerization plays a critical role in the regulation of p53. However, it remains unclear whether MDMX is essential for the regulation of p53 protein levels in the context of an endogenous MDM2 C-terminal tail mutation. Results Here, we studied the significance of MDM2-MDMX binding in an MDM2 E3 ligase deficient context using the MDM2Y487A mouse embryonic fibroblast (MEF) cells. Surprisingly, down-regulation of MDMX in MDM2Y487A MEFs resulted in a significant increase of p53 protein levels. Conversely, ectopic overexpression of MDMX reduced p53 protein levels in MDM2Y487A MEFs. Mutations of the RING domain of MDMX prevented MDMX-MDM2 binding, and ablated MDMX-mediated suppression of p53 protein expression. Additionally, DNA damage treatment and nuclear sequestration of MDMX inhibited MDMX activity to suppress p53 protein expression. Conclusions These results suggest that MDMX plays a key role in suppressing p53 protein expression in the absence of normal MDM2 E3 ligase activity. We found that the ability of MDMX to suppress p53 levels requires MDM2 binding and its cytoplasmic localization, and this ability is abrogated by DNA damage. Hence, MDMX is essential for the regulation of p53 protein levels in the context of an MDM2 C-terminal mutation that disrupts its E3 ligase activity but not MDMX binding. Our study is the first to examine the role of MDMX in the regulation of p53 in the context of endogenous MDM2 C-terminal mutant MEF cells.

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