Abstract 261: G3bp1-Gas5 Axis Regulates Glucocorticoid Receptor Signaling During Cardiac Hypertrophy

Congestive heart failure is one of the leading causes of mortality in US. With persistent work overload, pathological hypertrophy progresses into an irreversible state of dysfunction and failure. Understanding the mechanisms involved in these advances is crucial to prevent adverse changes in the heart. Studies show that Glucocorticoid (Gc) signaling and -dependent gene transcription promotes cardiac hypertrophy and fibrosis. High serum cortisol levels have been shown as independent risk factor for increased mortality in patients with cardiac failure. Gc activates cytosolic Glucocorticoid receptor (GR) that translocates to nucleus and regulates gene transcription by binding to genomic GR-response element (GRE). We confirmed nuclear translocation of GR in hypertrophing cardiac myocytes in vitro and in vivo . Our aim was to examine GR signaling in cardiac myocytes. Using in vitro biotin labeling and RNA immunoprecipitation we show that a non-coding RNA Gas5, which harbors decoy GRE sequence associates with GR in cardiac myocytes and competes with genomic GRE for DNA binding domain of GR, thus inhibiting the transcriptional effects of activated GR. Interestingly, this association decreases with hypertrophy or Gc agonist (dexamethasone) stimulation. Conversely, Gas5 association with G3bp1, a RNA binding protein increases in cardiac myocytes with similar stimulations, suggesting that increase in G3bp1-Gas5 binding might play a role in release of activated GR from Gas5. In accordance, expression of exogenous Gas5 in vitro and in vivo restricted hypertrophy, suggesting critical role in progression of hypertrophy. We recently reported that G3bp1 is required for development of cardiac hypertrophy. Moreover, in situ hybridization revealed sequestration of Gas5 transcripts to perinuclear focal regions with growth stimulus, which resemble cytoplasmic protein-RNA aggregates seen with hypertrophic stimulation or G3bp1 over expression in cardiac myocytes. These results suggest that G3bp1 regulates Gas5 cellular compartmental dynamics and hence its GR-repressor function in cardiac myocytes. Thus, we conclude that G3bp1-Gas5 axis regulates GR -dependent gene transcription and progression of pathological cardiac hypertrophy and onset of failure

Download Full-text

Inhibition of RANKL-Induced Osteoclastogenesis by Novel Mutant RANKL

International Journal of Molecular Sciences ◽

10.3390/ijms22010434 ◽

2021 ◽

Vol 22 (1) ◽

pp. 434

Author(s):

Yuria Jang ◽

Hong Moon Sohn ◽

Young Jong Ko ◽

Hoon Hyun ◽

Wonbong Lim

Keyword(s):

Nuclear Translocation ◽

Critical Role ◽

Osteoclast Differentiation ◽

Point Mutations ◽

Tartrate Resistant Acid Phosphatase ◽

Mice Model ◽

Gsk 3Β ◽

Rank Signaling

Background: Recently, it was reported that leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4, also called GPR48) is another receptor for RANKL and was shown to compete with RANK to bind RANKL and suppress canonical RANK signaling during osteoclast differentiation. The critical role of the protein triad RANK–RANKL in osteoclastogenesis has made their binding an important target for the development of drugs against osteoporosis. In this study, point-mutations were introduced in the RANKL protein based on the crystal structure of the RANKL complex and its counterpart receptor RANK, and we investigated whether LGR4 signaling in the absence of the RANK signal could lead to the inhibition of osteoclastogenesis.; Methods: The effects of point-mutated RANKL (mRANKL-MT) on osteoclastogenesis were assessed by tartrate-resistant acid phosphatase (TRAP), resorption pit formation, quantitative real-time polymerase chain reaction (qPCR), western blot, NFATc1 nuclear translocation, micro-CT and histomorphological assay in wild type RANKL (mRANKL-WT)-induced in vitro and in vivo experimental mice model. Results: As a proof of concept, treatment with the mutant RANKL led to the stimulation of GSK-3β phosphorylation, as well as the inhibition of NFATc1 translocation, mRNA expression of TRAP and OSCAR, TRAP activity, and bone resorption, in RANKL-induced mouse models; and Conclusions: The results of our study demonstrate that the mutant RANKL can be used as a therapeutic agent for osteoporosis by inhibiting RANKL-induced osteoclastogenesis via comparative inhibition of RANKL. Moreover, the mutant RANKL was found to lack the toxic side effects of most osteoporosis treatments.

Download Full-text

The Glucocorticoid Receptor in Cardiovascular Health and Disease

Cells ◽

10.3390/cells8101227 ◽

2019 ◽

Vol 8 (10) ◽

pp. 1227 ◽

Cited By ~ 7

Author(s):

Liu ◽

Zhang ◽

Knight ◽

Goodwin

Keyword(s):

Glucocorticoid Receptor ◽

Cardiovascular System ◽

Gene Networks ◽

Cardiovascular Health ◽

Critical Role ◽

Glucocorticoid Signaling ◽

Health And Disease ◽

Nuclear Receptor Family

The glucocorticoid receptor is a member of the nuclear receptor family that controls many distinct gene networks, governing various aspects of development, metabolism, inflammation, and the stress response, as well as other key biological processes in the cardiovascular system. Recently, research in both animal models and humans has begun to unravel the profound complexity of glucocorticoid signaling and convincingly demonstrates that the glucocorticoid receptor has direct effects on the heart and vessels in vivo and in vitro. This research has contributed directly to improving therapeutic strategies in human disease. The glucocorticoid receptor is activated either by the endogenous steroid hormone cortisol or by exogenous glucocorticoids and acts within the cardiovascular system via both genomic and non-genomic pathways. Polymorphisms of the glucocorticoid receptor are also reported to influence the progress and prognosis of cardiovascular disease. In this review, we provide an update on glucocorticoid signaling and highlight the critical role of this signaling in both physiological and pathological conditions of the cardiovascular system. With increasing in-depth understanding of glucocorticoid signaling, the future is promising for the development of targeted glucocorticoid treatments and improved clinical outcomes.

Download Full-text

YBX1 is required for maintaining myeloid leukemia cell survival by regulating BCL2 stability in an m6A-dependent manner

Blood ◽

10.1182/blood.2020009676 ◽

2021 ◽

Author(s):

Mengdie Feng ◽

Xueqin Xie ◽

Guoqiang Han ◽

Tiantian Zhang ◽

Yashu Li ◽

...

Keyword(s):

Cell Survival ◽

Myeloid Leukemia ◽

Rna Binding ◽

Rna Binding Proteins ◽

Critical Role ◽

Leukemia Cell ◽

Dependent Manner ◽

Myeloid Leukemia Cell

RNA-binding proteins (RBPs) are critical regulators of transcription and translation that are often dysregulated in cancer. Although RBPs are increasingly appreciated as being important for normal hematopoiesis and for hematological malignancies as oncogenes or tumor suppressors, essential RBPs for leukemia maintenance and survival remain elusive. Here we show that YBX1 is specifically required for maintaining myeloid leukemia cell survival in an m6A-dependent manner. We found that expression of YBX1 is significantly upregulated in myeloid leukemia cells, and deletion of YBX1 dramatically induces apoptosis, promotes differentiation, coupled with reduced proliferation and impaired leukemic capacity of primary human and mouse acute myeloid leukemia (AML) cells in vitro and in vivo. Loss of YBX1 does not obviously affect normal hematopoiesis. Mechanistically, YBX1 interacts with IGF2BPs and stabilizes m6A-tagged RNA. Moreover, YBX1 deficiency dysregulates the expression of apoptosis-related genes, and promotes mRNA decay of MYC and BCL2 in an m6A-dependent manner, which contributes to the defective survival due to YBX1 deletion. Thus, our findings uncover a selective and critical role of YBX1 in maintaining myeloid leukemia survival that might provide a rationale for the therapeutic targeting of YBX1 in myeloid leukemia.

Download Full-text

HNRNPH1 Is a Novel Regulator Of Cellular Proliferation and Disease Progression in Chronic Myeloid Leukemia

Frontiers in Oncology ◽

10.3389/fonc.2021.682859 ◽

2021 ◽

Vol 11 ◽

Author(s):

Menghan Liu ◽

Lin Yang ◽

Xiaojun Liu ◽

Ziyuan Nie ◽

Xiaoyan Zhang ◽

...

Keyword(s):

Chronic Myeloid Leukemia ◽

Disease Progression ◽

Myeloid Leukemia ◽

Cellular Proliferation ◽

Rna Binding ◽

Rna Binding Proteins ◽

Critical Role ◽

Multiple Cancer

RNA binding proteins act as essential modulators in cancers by regulating biological cellular processes. Heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1), as a key member of the heterogeneous nuclear ribonucleoproteins family, is frequently upregulated in multiple cancer cells and involved in tumorigenesis. However, the function of HNRNPH1 in chronic myeloid leukemia (CML) remains unclear. In the present study, we revealed that HNRNPH1 expression level was upregulated in CML patients and cell lines. Moreover, the higher level of HNRNPH1 was correlated with disease progression of CML. In vivo and in vitro experiments showed that knockdown of HNRNPH1 inhibited cell proliferation and promoted cell apoptosis in CML cells. Importantly, knockdown of HNRNPH1 in CML cells enhanced sensitivity to imatinib. Mechanically, HNRNPH1 could bind to the mRNA of PTPN6 and negatively regulated its expression. PTPN6 mediated the regulation between HNRNPH1 and PI3K/AKT activation. Furthermore, the HNRNPH1–PTPN6–PI3K/AKT axis played a critical role in CML tumorigenesis and development. The present study first investigated the deregulated HNRNPH1–PTPN6–PI3K/AKT axis moderated cell growth and apoptosis in CML cells, whereby targeting this pathway may be a therapeutic CML treatment.

Download Full-text

TGF-βRII regulates glucose metabolism in oral cancer-associated fibroblasts via promoting PKM2 nuclear translocation

Cell Death Discovery ◽

10.1038/s41420-021-00804-6 ◽

2022 ◽

Vol 8 (1) ◽

Author(s):

Fanglong Wu ◽

Shimeng Wang ◽

Qingxiang Zeng ◽

Junjiang Liu ◽

Jin Yang ◽

...

Keyword(s):

Glucose Metabolism ◽

Oral Cancer ◽

Nuclear Translocation ◽

Aerobic Glycolysis ◽

Critical Role ◽

Metabolic Reprogramming ◽

Cancer Associated Fibroblasts

AbstractCancer-associated fibroblasts (CAFs) are highly heterogeneous and differentiated stromal cells that promote tumor progression via remodeling of extracellular matrix, maintenance of stemness, angiogenesis, and modulation of tumor metabolism. Aerobic glycolysis is characterized by an increased uptake of glucose for conversion into lactate under sufficient oxygen conditions, and this metabolic process occurs at the site of energy exchange between CAFs and cancer cells. As a hallmark of cancer, metabolic reprogramming of CAFs is defined as reverse Warburg effect (RWE), characterized by increased lactate, glutamine, and pyruvate, etc. derived from aerobic glycolysis. Given that the TGF-β signal cascade plays a critical role in RWE mainly through metabolic reprogramming related proteins including pyruvate kinase muscle isozyme 2 (PKM2), however, the role of nuclear PKM2 in modifying glycolysis remains largely unknown. In this study, using a series of in vitro and in vivo experiments, we provide evidence that TGF-βRII overexpression suppresses glucose metabolism in CAFs by attenuating PKM2 nuclear translocation, thereby inhibiting oral cancer tumor growth. This study highlights a novel pathway that explains the role of TGF-βRII in CAFs glucose metabolism and suggests that targeting TGF-βRII in CAFs might represent a therapeutic approach for oral cancer.

Download Full-text

A Nucleolin-Binding 3′ Untranslated Region Element Stabilizes β-Globin mRNA In Vivo

Molecular and Cellular Biology ◽

10.1128/mcb.26.6.2419-2429.2006 ◽

2006 ◽

Vol 26 (6) ◽

pp. 2419-2429 ◽

Cited By ~ 51

Author(s):

Yong Jiang ◽

Xiang-Sheng Xu ◽

J. Eric Russell

Keyword(s):

Mrna Stability ◽

Untranslated Region ◽

Rna Binding ◽

Critical Role ◽

Specific Interaction ◽

Globin Mrna ◽

Intact Cells ◽

Normal Expression

ABSTRACT The normal expression of human β globin is critically dependent upon the constitutively high stability of its encoding mRNA. Unlike with α-globin mRNA, the specific cis-acting determinants and trans-acting factors that participate in stabilizing β-globin mRNA are poorly described. The current work uses a linker-scanning strategy to identify a previously unknown determinant of mRNA stability within the β-globin 3′ untranslated region (3′UTR). The new determinant is positioned on an mRNA half-stem opposite a pyrimidine-rich sequence targeted by αCP/hnRNP-E, a factor that plays a critical role in stabilizing human α-globin mRNA. Mutations within the new determinant destabilize β-globin mRNA in intact cells while also ablating its 3′UTR-specific interaction with the polyfunctional RNA-binding factor nucleolin. We speculate that 3′UTR-bound nucleolin enhances mRNA stability by optimizing αCP access to its functional binding site. This model is favored by in vitro evidence that αCP binding is enhanced both by cis-acting stem-destabilizing mutations and by the trans-acting effects of supplemental nucleolin. These studies suggest a mechanism for β-globin mRNA stability that is related to, but distinct from, the mechanism that stabilizes human α-globin mRNA.

Download Full-text

PARIS–DJ-1 Interaction Regulates Mitochondrial Functions in Cardiomyocytes, Which Is Critically Important in Cardiac Hypertrophy

Molecular and Cellular Biology ◽

10.1128/mcb.00106-20 ◽

2020 ◽

Vol 41 (1) ◽

pp. e00106-20

Author(s):

Dibyanti Mukherjee ◽

Vivek Chander ◽

Arun Bandyopadhyay

Keyword(s):

Oxidative Stress ◽

Cardiac Hypertrophy ◽

Feedback Loop ◽

Zinc Finger Protein ◽

Critical Role ◽

Finger Protein ◽

Mitochondrial Functions ◽

Resistant Mutants

ABSTRACTMitochondrial dysfunction is one of the major pathological attributes of cardiac hypertrophy and is associated with reduced expression of PGC1α in cardiomyocytes. However, the transcriptional regulation of PGC1α remains elusive. Here, we show that parkin interacting substrate (PARIS), a KRAB zinc finger protein, prevented PGC1α transcription despite the induction of cardiomyocytes with hypertrophic stimuli. Moreover, PARIS expression and its nuclear localization are enhanced in hypertrophy both in vitro and in vivo. Knocking down PARIS resulted in mitochondrial biogenesis and improved respiration and other biochemical features that were compromised during hypertrophy. Furthermore, a PARIS-dependent proteome showed exclusive binding of a deSUMOylating protein called DJ-1 to PARIS in control cells, while this interaction is completely abrogated in hypertrophied cells. We further demonstrate that proteasomal degradation of DJ-1 under oxidative stress led to augmented PARIS SUMOylation and consequent repression of PGC1α promoter activity. SUMOylation-resistant mutants of PARIS failed to repress PGC1α, suggesting a critical role for PARIS SUMOylation in hypertrophy. The present study, therefore, proposes a novel regulatory pathway where DJ-1 acts as an oxidative stress sensor and contributes to the feedback loop governing PARIS-mediated mitochondrial function.

Download Full-text

YB-1 regulates stress granule formation and tumor progression by translationally activating G3BP1

The Journal of Cell Biology ◽

10.1083/jcb.201411047 ◽

2015 ◽

Vol 208 (7) ◽

pp. 913-929 ◽

Cited By ~ 101

Author(s):

Syam Prakash Somasekharan ◽

Amal El-Naggar ◽

Gabriel Leprivier ◽

Hongwei Cheng ◽

Shamil Hajee ◽

...

Keyword(s):

Tumor Progression ◽

Rna Binding ◽

Rna Binding Proteins ◽

Critical Role ◽

Granule Formation ◽

Ribonucleoprotein Complexes ◽

Highly Correlated ◽

As Stress

Under cell stress, global protein synthesis is inhibited to preserve energy. One mechanism is to sequester and silence mRNAs in ribonucleoprotein complexes known as stress granules (SGs), which contain translationally silent mRNAs, preinitiation factors, and RNA-binding proteins. Y-box binding protein 1 (YB-1) localizes to SGs, but its role in SG biology is unknown. We now report that YB-1 directly binds to and translationally activates the 5′ untranslated region (UTR) of G3BP1 mRNAs, thereby controlling the availability of the G3BP1 SG nucleator for SG assembly. YB-1 inactivation in human sarcoma cells dramatically reduces G3BP1 and SG formation in vitro. YB-1 and G3BP1 expression are highly correlated in human sarcomas, and elevated G3BP1 expression correlates with poor survival. Finally, G3BP1 down-regulation in sarcoma xenografts prevents in vivo SG formation and tumor invasion, and completely blocks lung metastasis in mouse models. Together, these findings demonstrate a critical role for YB-1 in SG formation through translational activation of G3BP1, and highlight novel functions for SGs in tumor progression.

Download Full-text

CSIG-15. INNOVATIVE COMPUTATIONAL PLATFORM ADDRESSES PROSTAGLANDIN E RECEPTOR 3 AS THE MASTER REGULATOR MEDIATING RESISTANCE TO TUMOR TREATING FIELDS IN GLIOBLASTOMA CELLS

Neuro-Oncology ◽

10.1093/neuonc/noaa215.127 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii30-ii31

Author(s):

Dongjiang Chen ◽

Son Le ◽

Tarun Hutchinson ◽

David Tran

Keyword(s):

Nuclear Translocation ◽

Expression Profiles ◽

Critical Role ◽

Prolonged Treatment ◽

Prostaglandin E ◽

Tumor Treating Fields ◽

Computational Platform ◽

Resistant Cells

Abstract OBJECTIVES Tumor Treating Fields (TTFields) are approved in combination with temozolomide for newly diagnosed glioblastoma (GBM). TTFields are low-intensity alternating electric fields that are thought to disturb mitotic macromolecules’ assembly. The addition of TTFields resulted in a significant improvement in overall survival. However, most GBM patients eventually develop resistance to TTFields and the mechanism remains unexplored. METHODS Multiple GBM cell lines were treated continuously at clinically approved frequency of 200 kHz using an in vitro TTFields system until cells with relative resistance to the cytotoxic effects of TTFields. A systems approach aided by innovative network ranking computational algorithms were utilized to analyze global gene expression profiles and identify resistance pathways, which were subsequently validated experimentally. RESULTS TTFields-induced chromosomal instability is preserved in resistant cells, indicating that TTFields resistance is mediated through a non-biophysical mechanism. This acquired TTFields resistance phenotype is associated with a transition of GBM cells to a stem-like state as determined by a neurosphere assay, stemness markers such as CD44 and increased tumorigenesis when implanted into mouse brain. Using an innovative computational platform-NETZEN, we methodically dissected this stemness program in resistant cells. 3 networks were found disrupted and all play critical roles in GBM stemness. Mechanistically, Prostaglandin E Receptor 3 (PTGER3) is the top ranked regulator responsible for resistance. PTGER3 is rapidly upregulated both in vitro and in vivo upon exposure to TTFields and further increases with prolonged treatment as resistance sets in. Immunofluorescence staining shows PTGER3’s nuclear translocation along with Lamin A/C disruption in response to TTFields. Pharmacological inhibition of PTGER3 using aspirin or PTGER3-specific inhibitors resensitized or prevent cells becoming resistance to TTFields. CONCLUSIONS We have identified a novel regulator PTGER3 at the apex that plays a critical role in TTFields resistance. This is a potential therapeutic target to reduce resistance to TTFields therapy in GBM.

Download Full-text