Phosphorylation of cold shock domain/Y-box proteins by ERK2 and GSK3β and repression of the human VEGF promoter

YBX1 promotes type H vessel-dependent bone formation in an m5C-dependent manner

RNA-binding proteins (RBPs) interact with RNA and ubiquitously regulate RNA transcripts during their life cycle, playing a fundamental role in the progression of angiogenesis-related diseases. In the skeletal system, endothelium-dependent angiogenesis is indispensable for bone formation. However, the role of RBPs in endothelium-dependent bone formation is unclear. Here, we show that RBP-Y-box-binding protein 1 (YBX1) was strongly reduced in the bone vasculature of ovariectomy (OVX) mice. Endothelial cell-specific deletion of Ybx1 impaired CD31-high, endomucin-high (CD31hiEMCNhi) endothelium morphology and resulted in low bone mass whereas Ybx1 overexpression promoted angiogenesis-dependent osteogenesis and ameliorated bone loss. Mechanistically, YBX1 deletion disrupted CD31, EMCN, and bone morphogenetic protein 4 (BMP4) stability in an m5C-dependent manner and blocked endothelium-derived BMP4 release, thereby inhibiting osteogenic differentiation of bone mesenchymal stromal cells. Administration of recombinant BMP4 protein restored impaired bone formation in Ybx1 deletion mice. Tail vein injection of CD31-modified polyethylene glycol-poly (lactic-co-glycolic acid) carrying sciadopitysin, a natural YBX1 agonist, pharmacologically partially reversed CD31hiEMCNhi vessels' decline and improved bone mass in both OVX and aging animals. These findings demonstrated the role of RBP-YBX1 in angiogenesis-dependent bone formation and provided a therapeutic approach for ameliorating osteoporosis.

Local YB-1, Epo, and EpoR concentrations in fractured bones: results from a porcine model of multiple trauma

Little is known about the impact of multiple trauma (MT)-related systemic hypoxia on osseous protein concentration of the hypoxia transcriptome. To shed light on this issue, we investigated erythropoietin (Epo), erythropoietin receptor (EpoR), and Y-box binding protein 1 (YB-1) concentrations in the fracture zone in a porcine MT + traumatic hemorrhage (TH) model. Sixteen male domestic pigs were randomized into two groups: an MT + TH group and a sham group. A tibia fracture, lung contusion, and TH were induced in the MT + TH group. The total observation period was 72 h. YB-1 concentrations in bone marrow (BM) were significantly lower in the fracture zone of the MT + TH animals than in the sham animals. Significant downregulation of BM-localized EpoR concentration in both unfractured and fractured bones was observed in the MT + TH animals relative to the sham animals. In BM, Epo concentrations were higher in the fracture zone of the MT + TH animals compared with that in the sham animals. Significantly higher Epo concentrations were detected in the BM of fractured bone compared to that in cortical bone. Our results provide the first evidence that MT + TH alters hypoxia-related protein concentrations. The impacts of both the fracture and concomitant injuries on protein concentrations need to be studied in more detail to shed light on the hypoxia transcriptome in fractured and healthy bones after MT + TH.

RNA-binding proteins and translation control in angiogenesis

Tissue vascularization through the process of angiogenesis ensures adequate oxygen and nutrient supply during development and regeneration. The complex morphogenetic events involved in new blood vessel formation are orchestrated by a tightly regulated crosstalk between extra and intracellular factors. In this context, RNA-binding protein (RBP) activity and protein translation play fundamental roles during the cellular responses triggered by particular environmental cues. A solid body of work has demonstrated that key RBPs (such as HuR, TIS11 proteins, hnRNPs, NF90, QKIs and YB1) are implicated in both physiological and pathological angiogenesis. These RBPs are critical for the metabolism of messenger (m)RNAs encoding angiogenic modulators and, importantly, strong evidence suggests that RBP-mRNA interactions can be altered in disease. Lesser known, but not less important, the mechanistic aspects of protein synthesis can also regulate the generation of new vessels. In this review, we outline the key findings demonstrating the implications of RBP-mediated RNA regulation and translation control in angiogenesis. Furthermore, we highlight how these mechanisms of post-transcriptional control of gene expression have led to promising therapeutic strategies aimed at targeting undesired blood vessel formation.

The fiber diameter traits of Tibetan cashmere goats are governed by the inherent differences in stress, hypoxic, and metabolic adaptations: an integrative study of proteome and transcriptome

Background

Tibetan cashmere goats are served as a valuable model for high altitude adaptation and hypoxia complications related studies, while the cashmere produced by these goats is an important source of income for the herders. The aim of this study was to investigate the differences in protein abundance underlying the fine (average 12.20 ± 0.03 μm of mean fiber diameter) and coarse cashmere (average 14.67 ± 0.05 μm of mean fiber diameter) producing by Tibetan cashmere goats. We systematically investigated the genetic determinants of fiber diameter by integrated analysis with proteomic and transcriptomic datasets from skin tissues of Tibetan cashmere goats.

Results

We identified 1980 proteins using a label-free proteomics approach. They were annotated to three different databases, while 1730 proteins were mapped to the original protein coding genes (PCGs) of the transcriptomic study. Comparative analyses of cashmere with extremely fine vs. coarse phenotypes yielded 29 differentially expressed proteins (DEPs), for instance, APOH, GANAB, AEBP1, CP, CPB2, GPR142, VTN, IMPA1, CTSZ, GLB1, and HMCN1. Functional enrichment analysis of these DEPs revealed their involvement in oxidation-reduction process, cell redox homeostasis, metabolic, PI3K-Akt, MAPK, and Wnt signaling pathways. Transcription factors enrichment analysis revealed the proteins mainly belong to NF-YB family, HMG family, CSD family. We further validated the protein abundance of four DEPs (GC, VTN, AEBP1, and GPR142) through western blot, and considered they were the most potential candidate genes for cashmere traits in Tibetan cashmere goats.

Conclusions

These analyses indicated that the major biological variations underlying the difference of cashmere fiber diameter in Tibetan cashmere goats were attributed to the inherent adaptations related to metabolic, hypoxic, and stress response differences. This study provided novel insights into the breeding strategies for cashmere traits and enhance the understanding of the biological and genetic mechanisms of cashmere traits in Tibetan cashmere goats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08422-x.

The roles of Y-box-binding protein (YB)-1 and C-X-C motif chemokine ligand 14 (CXCL14) in the progression of prostate cancer via extracellular-signal-regulated kinase (ERK) signaling

The cold-shock protein Y-box-binding protein (YB)-1 regulates the expression of various chemokines and their receptors at the transcriptional level. Expression of the orphan chemokine CXCL14 is repressed by EGF induced signaling. The possible links between EGF-mediated YB-1 and CXCL14 as well as the functions of critical kinase pathways in the progression of prostate cancer have remained unexplored. Here we examined the correlation between YB-1 and CXCL14, and the ERK/AKT/mTOR pathways in prostate cancer. Knockdown of YB-1 decreased cyclinD1 expression with an upregulation of cleaved-PARP in human prostate cancer cells. EGF treatment upregulated phospho-YB-1 expression in a time-dependent manner, while treatment with an ERK inhibitor completely silenced its expression in prostate cancer cells. EGF treatment stimulates CyclinD1 and YB-1 phosphorylation in an ERK-dependent pathway. Positive and negative regulation of YB-1 and CXCL14 was observed after EGF treatment in prostate cancer cells, respectively. EGF rescues cell cycle and apoptosis via the AKT and ERK pathways. Furthermore, YB-1 silencing induces G1 arrest and apoptosis, while knockdown of CXCL14 facilitates cell growth and inhibits apoptosis in prostate cancer cells. YB-1 and CXCL14 were inversely correlated in prostate cancer cells and tissues. A significant association between poor overall survival and High YB-1 expression was observed in human prostate cancer patients. In conclusion, our data reveal the functional relationship between YB-1 and CXCL14 in EGF mediated ERK signaling, and YB-1 expression is a significant prognostic marker to predict prostate cancer.

Targeting the Y-box Binding Protein-1 Axis to Overcome Radiochemotherapy Resistance in Solid Tumors

Multifunctional Y-box binding protein-1 (YB-1) is highly expressed in different human solid tumors and is involved in various cellular processes. DNA damage is the major mechanism by which radiochemotherapy (RCT) induces cell death. On induction of DNA damage, a multicomponent signal transduction network, known as the DNA damage response, is activated to induce cell cycle arrest and initiate DNA repair, which protects cells against damage. YB-1 regulates nearly all cancer hallmarks described to date by participating in DNA damage response, gene transcription, mRNA splicing, translation, and tumor stemness. YB-1 lacks kinase activity, and p90 ribosomal S6 kinase and AKT are the key kinases within the RAS/mitogen-activated protein kinase and phosphoinositide 3-kinase pathways that directly activate YB-1. Thus, the molecular targeting of ribosomal S6 kinase and AKT is thought to be the most effective strategy for blocking the cellular function of YB-1 in human solid tumors. In this review, after describing the prosurvival effect of YB-1 with a focus on DNA damage repair and cancer cell stemness, clinical evidence will be provided indicating an inverse correlation between YB-1 expression and the treatment outcome of solid tumors after RCT. In the interest of being concise, YB-1 signaling cascades will be briefly discussed and the current literature on YB-1 posttranslational modifications will be summarized. Finally, the current status of targeting the YB-1 axis, especially in combination with RCT, will be highlighted.

Potential Links between YB-1 and Fatty Acid Synthesis in Clear Cell Renal Carcinoma

According to the National Institutes of Health, clear cell renal cell carcinoma (ccRCC) is the most common type of Renal Cell Carcinoma (RCC), making up approximately 75% of total renal carcinoma cases. Clear cell Renal Cell Carcinoma is characterized by a significant accumulation of lipids in the cytoplasm, which allows light from microscopes to pass through giving them a "clear" phenotype. Many of these lipids are in the form of fatty acids, both free and incorporated into lipid droplets. RCC is typically associated with a poor prognosis due to the lack of specific symptoms. Some symptoms include blood in urine, fever, lump on the side, weight loss, fatigue, to name a few; all of which can be associated with non-specific, non-cancerous, health conditions that contribute to difficult diagnosis. Treatment of RCC has typically been centered around radical nephrectomy as the standard of care, but due to the potentially small size of lesions and the possibility of causing surgically induced chronic kidney disease, treatments have shifted to more cautious, less invasive approaches. These approaches include active surveillance, nephron-sparing surgery, and other minimally invasive techniques like cryotherapy and renal ablation. Although these techniques have had the desired effect of reducing the number of surgeries, there is still considerable potential for renal impairment and the chance that tumors can grow out of control without surgery. With the difficulty that surrounds the treatment of ccRCC and its considerably high mortality rate amongst urological cancers, it is important to look for novel approaches to improve patient outcomes. This review looks at available literature and our data that suggests the lipogenic enzyme stearoyl-CoA desaturase may be more beneficial to patient survival than once thought. As our understanding of the importance of lipids in cell metabolism and longevity matures, it is important to present new perspectives that present a new understanding of ccRCC and the role of lipids in survival mechanisms engaged by transformed cells during cancer progression. In this review, we provide evidence that pharmacological inhibition of lipid desaturation in renal cancer patients is not without risk, and that the presence of unsaturated fatty acids may be a beneficial factor in patient outcomes. Although more direct experimental evidence is needed to make definitive conclusions, it is clear that the work reviewed herein should challenge our current understanding of cancer biology and may inform novel approaches to the diagnosis and treatment of ccRCC.

YB1 protects cardiac myocytes against H2O2‑induced injury via suppression of PIAS3 mRNA and phosphorylation of STAT3

Oxidative stress serves important roles in cardiac injury during the process of ischemia/reperfusion (I/R). Y-box protein 1 (YB1), a member of the highly conserved Y-box protein family, is closely associated with inflammation and stress responses by regulating gene transcription, RNA splicing and mRNA translation. However, the roles of YB1 in oxidative stress-induced myocardial-I/R (M-I/R) injury are unknown. The aim of the present study was to examine the effects of YB1 on H₂O₂-induced cardiomyocyte injury and its underlying mechanism. The results demonstrated that YB1 expression was upregulated during H₂O₂-induced myocardial injury. YB1 knockdown through transfection of small interfering RNA significantly aggravated cardiac cell apoptosis. Furthermore, YB1 knockdown significantly reversed the H₂O₂-mediated increase in phosphorylated signal transducer and activator of transcription (STAT)3, but did not affect the phosphorylation of P38, extracellular signal-regulated kinases 1/2, c-Jun N-terminal kinases, P65, Janus kinase 1 and 2 or STAT1. Moreover, protein co-immunoprecipitation and RNA-binding protein immunoprecipitation assays revealed that YB1 interacted with protein inhibitor of activated STAT 3 (PIAS3) mRNA but not its translated protein. YB1 overexpression may have promoted PIAS3 mRNA decay, decreasing PIAS3 protein levels, and therefore increased the levels of phosphorylated STAT3. Finally, YB1 knockdown, mediated by a lentivirus carrying YB1 targeted short hairpin RNA, significantly decreased left ventricle percentage fractional shortening and ejection fraction values, while increasing the infarct sizes in a rat model of M-I/R injury. These results demonstrated for the first time (to the best of our knowledge) that YB1 may protect cardiac myocytes against H₂O₂ or M-I/R-induced injury by binding to PIAS3 mRNA and resulting in the phosphorylation of STAT3.

The long noncoding RNA LINC00312 induces lung adenocarcinoma migration and vasculogenic mimicry through directly binding YBX1

Vasculogenic mimicry (VM) gives rise to tumor neovascularization that is critical for tumor growth and metastasis. Long non-coding RNAs (lncRNAs) have been implicated in diverse and fundamental biological processes. LINC00312 is associated with lung adenocarcinoma. In this study, we found that LINC00312 induced migration, invasion and VM of lung cancer cells by direct binding to the transcription factor Y-Box Binding Protein 1 (YBX1). Moreover, we demonstrated that YBX1 is associated with different fragments within 0-2410 nt 5'region of LINC00312. In addition, LINC00312 is associated with VM in 124 lung adenocarcinoma clinical specimens. The results suggest that LINC00312 is a promising therapeutic and diagnostic target for lung adenocarcinoma.

Cold shock proteins: from cellular mechanisms to pathophysiology and disease

Cold shock proteins are multifunctional RNA/DNA binding proteins, characterized by the presence of one or more cold shock domains. In humans, the best characterized members of this family are denoted Y-box binding proteins, such as Y-box binding protein-1 (YB-1). Biological activities range from the regulation of transcription, splicing and translation, to the orchestration of exosomal RNA content. Indeed, the secretion of YB-1 from cells via exosomes has opened the door to further potent activities. Evidence links a skewed cold shock protein expression pattern with cancer and inflammatory diseases. In this review the evidence for a causative involvement of cold shock proteins in disease development and progression is summarized. Furthermore, the potential application of cold shock proteins for diagnostics and as targets for therapy is elucidated.

Expression and network analysis of YBX1 interactors for identification of new drug targets in lung adenocarcinoma

Y-Box Binding protein 1 (YBX-1) is known to be involved in various types of cancers. It's interactors also play major role in various cellular functions. Present work aimed to study the expression profile of the YBX-1 interactors during lung adenocarcinoma (LUAD). The differential expression analysis involved 57 genes from 95 lung adenocarcinoma samples, construction of gene network and topology analysis. A Total of 43 genes were found to be differentially expressed from which 17 genes were found to be down regulated and 26 genes were up-regulated. We observed that Polyadenylate-binding protein 1 (PABPC1), a protein involved in YBX1 translation, is highly correlated with YBX1. The interaction network analysis for a differentially expressed non-coding RNA Growth Arrest Specific 5 (GAS5) suggests that two proteins namely, Growth Arrest Specific 2 (GAS2) and Peripheral myelin protein 22 (PMP22) are potentially involved in LUAD progression. The network analysis and differential expression suggests that Collagen type 1 alpha 2 (COL1A2) can be potential biomarker and target for LUAD.

Kinase-loaded magnetic beads for sequentialin vitrophosphorylation of peptides and proteins

Kinases ERK2 and GSK-3β loaded magnetic beads for sequentialin vitrophosphorylation of peptides and proteins.

Protein Translation and Signaling in Human Eosinophils

We have recently reported that, unlike IL-5 and GM-CSF, IL-3 induces increased translation of a subset of mRNAs. In addition, we have demonstrated that Pin1 controls the activity of mRNA binding proteins, leading to enhanced mRNA stability, GM-CSF protein production and prolonged eosinophil (EOS) survival. In this review, discussion will include an overview of cap-dependent protein translation and its regulation by intracellular signaling pathways. We will address the more general process of mRNA post-transcriptional regulation, especially regarding mRNA binding proteins, which are critical effectors of protein translation. Furthermore, we will focus on (1) the roles of IL-3-driven sustained signaling on enhanced protein translation in EOS, (2) the mechanisms regulating mRNA binding proteins activity in EOS, and (3) the potential targeting of IL-3 signaling and the signaling leading to mRNA binding activity changes to identify therapeutic targets to treat EOS-associated diseases.

Antisense Oligonucleotides Targeting Y-Box Binding Protein-1 Inhibit Tumor Angiogenesis by Downregulating Bcl-xL-VEGFR2/-Tie Axes

Y-box binding protein-1 (YB-1), involved in cancer progression and chemoradiation resistance, is overexpressed in not only cancer cells but also tumor blood vessels. In this study, we investigated the potential value of amido-bridged nucleic acid (AmNA)-modified antisense oligonucleotides (ASOs) targeting YB-1 (YB-1 ASO^A) as an antiangiogenic cancer therapy. YB-1 ASO^A was superior to natural DNA-based ASO or locked nucleic acid (LNA)-modified YB-1 ASO in both knockdown efficiency and safety, the latter assessed by liver function. YB-1 ASO^A administered i.v. significantly inhibited YB-1 expression in CD31-positive angiogenic endothelial cells, but not in cancer cells, in the tumors. With regard to the mechanism of its antiangiogenic effects, YB-1 ASO^A downregulated both Bcl-xL/VEGFR2 and Bcl-xL/Tie signal axes, which are key regulators of angiogenesis, and induced apoptosis in vascular endothelial cells. In the xenograft tumor model that had low sensitivity to anti-VEGF antibody, YB-1 ASO^A significantly suppressed tumor growth; not only VEGFR2 but also Tie2 expression was decreased in tumor vessels. In conclusion, YB-1/Bcl-xL/VEGFR2 and YB-1/Bcl-xL/Tie signal axes play pivotal roles in tumor angiogenesis, and YB-1 ASO^A may be feasible as an antiangiogenic therapy for solid tumors.

Long noncoding RNA HULC modulates the phosphorylation of YB-1 through serving as a scaffold of extracellular signal-regulated kinase and YB-1 to enhance hepatocarcinogenesis

Dysregulated expression of long noncoding RNAs has been reported in many types of cancers, indicating that it may play a critical role in tumorigenesis. The long noncoding RNA highly up-regulated in liver cancer (HULC) was first characterized in hepatocellular carcinoma. However, the detailed mechanisms of HULC remain unclear. Here, we demonstrate a novel mechanism by which long noncoding RNA plays oncogenic roles through modulating the phosphorylation status of its interaction protein. First, we validated the markedly increased expression levels of HULC in hepatocellular carcinoma tissues compared to their adjacent noncancerous tissues. Furthermore, up-regulation of HULC was correlated with grading and overall survival. Meanwhile, HULC could promote cell proliferation, migration, and invasion in vitro and inhibit cisplatin-induced apoptosis. Moreover, we show that HULC specifically binds to Y-box binding protein 1 (YB-1) protein both in vitro and in vivo. YB-1 is a major component of translationally inactive messenger ribonucleoprotein particles which keeps mRNA in a silent state. Our study further demonstrated that HULC could promote the phosphorylation of YB-1 protein, which leads to the release of YB-1 from its bound mRNA. As a consequence, translation of silenced oncogenic mRNAs would be activated, including cyclin D1, cyclin E1, and matrix metalloproteinase 3. In addition, we found that HULC promotes the phosphorylation of YB-1 protein mainly through extracellular signal-regulated kinase.

CONCLUSION

We demonstrate that HULC promotes the phosphorylation of YB-1 through the extracellular signal-regulated kinase pathway, in turn regulates the interaction of YB-1 with certain oncogenic mRNAs, and consequently accelerates the translation of these mRNAs in the process of tumorigenesis. (Hepatology 2017;65:1612-1627).

Extracellular Signal-regulated Kinase (ERK)-dependent Phosphorylation of Y-Box-binding Protein 1 (YB-1) Enhances Gene Expression in Granulosa Cells in Response to Follicle-stimulating Hormone (FSH)

Within the ovarian follicle, immature oocytes are surrounded and supported by granulosa cells (GCs). Stimulation of GCs by FSH leads to their proliferation and differentiation, events that are necessary for fertility. FSH activates multiple signaling pathways to regulate genes necessary for follicular maturation. Herein, we investigated the role of Y-box-binding protein-1 (YB-1) within GCs. YB-1 is a nucleic acid binding protein that regulates transcription and translation. Our results show that FSH promotes an increase in the phosphorylation of YB-1 on Ser(102) within 15 min that is maintained at significantly increased levels until ∼8 h post treatment. FSH-stimulated phosphorylation of YB-1(Ser(102)) is prevented by pretreatment of GCs with the PKA-selective inhibitor PKA inhibitor (PKI), the MEK inhibitor PD98059, or the ribosomal S6 kinase-2 (RSK-2) inhibitor BI-D1870. Thus, phosphorylation of YB-1 on Ser(102) is PKA-, ERK-, and RSK-2-dependent. However, pretreatment of GCs with the protein phosphatase 1 (PP1) inhibitor tautomycin increased phosphorylation of YB-1(Ser(102)) in the absence of FSH; FSH did not further increase YB-1(Ser(102)) phosphorylation. This result suggests that the major effect of RSK-2 is to inhibit PP1 rather than to directly phosphorylate YB-1 on Ser(102) YB-1 coimmunoprecipitated with PP1β catalytic subunit and RSK-2. Transduction of GCs with the dephospho-adenoviral-YB-1(S102A) mutant prevented the induction by FSH of Egfr, Cyp19a1, Inha, Lhcgr, Cyp11a1, Hsd17b1, and Pappa mRNAs and estradiol-17β production. Collectively, our results reveal that phosphorylation of YB-1 on Ser(102) via the ERK/RSK-2 signaling pathway is necessary for FSH-mediated expression of target genes required for maturation of follicles to a preovulatory phenotype.

[YB-1-based virotherapy: A new therapeutic intervention for transitional cell carcinoma of the bladder?]

Therapeutic intervention using oncolytic viruses is called virotherapy. This type of virus is defined by the ability to replicate in tumor cells only and to destroy these cells upon replication. In addition, this virus type is able to induce a tumor-directed immune response. Early clinical trials have confirmed the safety profile of oncolytic viruses. Currently, different groups are working on the development of oncolytic viruses with a focus on treatment of nonmuscle invasive bladder cancer (NMIBC). A preliminary active recruiting clinical phase II/III trial ongoing in patients with a NMIBC was recently implemented in the United States. Our research group developed an oncolytic adenovirus that will soon enter a clinical phase I trial in patients diagnosed with glioma. This virus is being further modified for the treatment of NMIBC. In this review article, recent developments in the design and use of virotherapy in bladder cancer are summarized.

Poly(ADP-ribosyl)ation as a new posttranslational modification of YB-1

Multifunctional Y-box binding protein 1 (YB-1) is actively studied as one of the components of cellular response to genotoxic stress. However, the precise role of YB-1 in the process of DNA repair is still obscure. In the present work we report for the first time new posttranslational modification of YB-1 - poly(ADP-ribosyl)ation, catalyzed by one of the main regulatory enzymes of DNA repair - poly(ADP-ribose)polymerase 1 (PARP1) in the presence of model DNA substrate carrying multiple DNA lesions. Therefore, poly(ADP-ribosyl)ation of YB-1 catalyzed with PARP1, can be stimulated by damaged DNA. The observed property of YB-1 underlines its ability to participate in the DNA repair by its involvement in the regulatory cascades of DNA repair.

Akt-mediated phosphorylation controls the activity of the Y-box protein MSY3 in skeletal muscle

BACKGROUND

The Y-box protein MSY3/Csda represses myogenin transcription in skeletal muscle by binding a highly conserved cis-acting DNA element located just upstream of the myogenin minimal promoter (myogHCE). It is not known how this MSY3 activity is controlled in skeletal muscle. In this study, we provide multiple lines of evidence showing that the post-translational phosphorylation of MSY3 by Akt kinase modulates the MSY3 repression of myogenin.

METHODS

Skeletal muscle and myogenic C2C12 cells were used to study the effects of MSY3 phosphorylation in vivo and in vitro on its sub-cellular localization and activity, by blocking the IGF1/PI3K/Akt pathway, by Akt depletion and over-expression, and by mutating potential MSY3 phosphorylation sites.

RESULTS

We observed that, as skeletal muscle progressed from perinatal to postnatal and adult developmental stages, MSY3 protein became gradually dephosphorylated and accumulated in the nucleus. This correlated well with the reduction of phosphorylated active Akt. In C2C12 myogenic cells, blocking the IGF1/PI3K/Akt pathway using LY294002 inhibitor reduced MSY3 phosphorylation levels resulting in its accumulation in the nuclei. Knocking down Akt expression increased the amount of dephosphorylated MSY3 and reduced myogenin expression and muscle differentiation. MSY3 phosphorylation by Akt in vitro impaired its binding at the MyogHCE element, while blocking Akt increased MSY3 binding activity. While Akt over-expression rescued myogenin expression in MSY3 overexpressing myogenic cells, ablation of the Akt substrate, (Ser126 located in the MSY3 cold shock domain) promoted MSY3 accumulation in the nucleus and abolished this rescue. Furthermore, forced expression of Akt in adult skeletal muscle induced MSY3 phosphorylation and myogenin derepression.

CONCLUSIONS

These results support the hypothesis that MSY3 phosphorylation by Akt interferes with MSY3 repression of myogenin circuit activity during muscle development. This study highlights a previously undescribed Akt-mediated signaling pathway involved in the repression of myogenin expression in myogenic cells and in mature muscle. Given the significance of myogenin regulation in adult muscle, the Akt/MSY3/myogenin regulatory circuit is a potential therapeutic target to counteract muscle degenerative disease.

Tip110 Regulates the Cross Talk between p53 and Hypoxia-Inducible Factor 1α under Hypoxia and Promotes Survival of Cancer Cells

Hypoxia often occurs under various physiological and pathophysiological conditions, including solid tumors; it is linked to malignant transformation, metastatic progression, and treatment failure or resistance. Tip110 protein plays important roles in several known physiological and pathophysiological processes, including cancers. Thus, in the present study we investigated the regulation of Tip110 expression under hypoxia. Hypoxia led to Tip110 protein degradation through the ubiquitin-proteasome system. Under hypoxia, Tip110 stabilized p53, which in return destabilized Tip110. In addition, Tip110 regulated hypoxia-inducible factor 1α (HIF-1α), likely through enhancement of its protein stability. Furthermore, Tip110 upregulated p300, a known coactivator for both p53 and HIF-1α. Expression of a p53(22/23) mutant deficient in p300 binding accelerated Tip110 degradation under hypoxia. Tip110 knockdown resulted in the inhibition of cell proliferation and cell death in the presence of p53. Finally, significantly less Tip110, p53, and HIF-1α was detected in the hypoxic region of bone metastasis tumors in a mouse model of human melanoma cells. Taken together, these results suggest Tip110 is an important mediator in the cross talk between p53 and HIF-1α in response to hypoxic stress.

Regulation of AU-Rich Element RNA Binding Proteins by Phosphorylation and the Prolyl Isomerase Pin1

The accumulation of 3' untranslated region (3'-UTR), AU-rich element (ARE) containing mRNAs, are predominantly controlled at the post-transcriptional level. Regulation appears to rely on a variable and dynamic interaction between mRNA target and ARE-specific binding proteins (AUBPs). The AUBP-ARE mRNA recognition is directed by multiple intracellular signals that are predominantly targeted at the AUBPs. These include (but are unlikely limited to) methylation, acetylation, phosphorylation, ubiquitination and isomerization. These regulatory events ultimately affect ARE mRNA location, abundance, translation and stability. In this review, we describe recent advances in our understanding of phosphorylation and its impact on conformation of the AUBPs, interaction with ARE mRNAs and highlight the role of Pin1 mediated prolyl cis-trans isomerization in these biological process.

Establishment of a novel cell line for the enhanced production of recombinant adeno-associated virus vectors for gene therapy

Adeno-associated viral (AAV) vectors show great promise because of their excellent safety profile; however, pre-existing immune responses have necessitated the administration of high titer AAV, posing a significant challenge to the advancement of gene therapy involving AAV vectors. Recombinant AAV vectors contain minimum viral proteins necessary for their assembly and gene delivery functions. During the process of AAV assembly and production, AAV vectors acquire, inherently and submissively, various cellular proteins, but the identity of these proteins is poorly characterized. We reason that by identifying host cell proteins inherently associated with AAV vectors we may better understand the contribution of cellular components to AAV vector assembly and, ultimately, may improve the production of AAV vectors for gene therapy. In this study, three serotypes of recombinant AAV, namely AAV2, AAV5, and AAV8, were investigated. We used liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) methods to identify protein composition in purified AAV vectors, confirmed protein identities using western blotting, and explored the potential function of selected proteins in AAV vector production using small hairpin (shRNA) methods. Using LC-MS/MS, we identified 44 AAV-associated cellular proteins including Y-box binding protein (YB1). We showed for the first time that the establishment of a novel producer cell line by introducing an shRNA sequence down-regulating YB1 resulted in up to 45- and 9-fold increase in physical vector genome titers of AAV2 and AAV8, respectively, and up to 7-fold increase in AAV2 transduction vector genome titers. Our results revealed that YB1 gene knockdown promoted AAV2 rep expression and vector DNA production and reduced the number of empty particles in AAV2 products, suggesting that YB1 plays an important role in AAV vector assembly by competition with adenovirus E2A and AAV capsid proteins for binding to the inverted terminal repeat (ITR) sequence. The significance and implications of our findings in future improvement of AAV production are discussed.

Targeting ribosomal S6 kinases/Y-box binding protein-1 signaling improves cellular sensitivity to taxane in prostate cancer

BACKGROUND

Taxanes are the only cytotoxic chemotherapeutic agents proved to prolong the survival in patients with castration-resistant prostate cancer. However, because of intrinsic and acquired resistances to taxanes, their therapeutical efficiencies are modest, bringing only a few months of survival benefit. Y-box binding protein-1 (YB-1) promotes cancer cell resistance to various anticancer treatments, including taxanes. Here, we aimed to elucidate the mechanism of taxane resistance by YB-1 and examined overcoming resistance by targeting YB-1 signaling.

METHODS

Gene and protein expression levels were evaluated by quantitative real-time polymerase chain reaction and Western blot analysis, respectively. We evaluated the sensitivity of prostate cancer cells to taxanes using cytotoxicity assays.

RESULTS

Natural taxane paclitaxel from Taxus brevifolia activated the Raf-1/extracellular signal-regulated kinase (ERK) pathway, leading to an activation of ribosomal S6 kinases (RSK)/YB-1 signaling. Activated Raf-1/ERK pathway was blunted by YB-1 knockdown in prostate cancer cells, indicating regulation between Raf-1/ERK signaling and YB-1. In addition, ERK or RSK was activated in taxane-resistant prostate cancer cells, resulting in YB-1 activation. YB-1 knockdown as well as RSK inhibition using RSK-specific siRNA or the small molecule inhibitor SL0101 successfully blocked activation of YB-1, leading to suppression of prostate cancer growth and sensitization to paclitaxel.

CONCLUSIONS

Taken together, these findings indicate that RSK/YB-1 signaling contributes to taxane resistance, and implicate the therapeutics targeting RSK/YB-1 signaling such as RSK inhibitor as a promising novel therapy against prostate cancer, especially in combination with taxane.

YB-1 regulates Sox2 to coordinately sustain stemness and tumorigenic properties in a phenotypically distinct subset of breast cancer cells

BACKGROUND

Sox2, a transcription factor and an embryonic stem cell marker, has been implicated in the pathogenesis of breast cancer (BC). YB-1 is another transcription factor that has been shown to promote stemness in BC cells.

METHODS

Western blotting, quantitative PCR, and siRNAs were used to query the regulatory relationships between YB-1, Sox2, and their downstream targets. Chromatin immunoprecipitation was used to detect YB-1 interactions at the Sox2 promoter. Mammosphere and soft agar assays were used to assess the phenotypic consequences of YB-1 knockdown.

RESULTS

Here, we report that YB-1 regulates Sox2. YB-1 was found to bind to the SOX2 promoter and down-regulate its expression in MCF7 and ZR751. The regulatory interaction between YB-1 and Sox2 was drastically different between the two phenotypically distinct cell subsets, purified based on their differential response to a Sox2 reporter. They are referred to as the reporter unresponsive (RU) cells and the reporter responsive (RR) cells. Upon siRNA knockdown of YB-1, RU cells showed an increase in Sox2 expression but no change in Sox2 reporter activity; in contrast, RR cells exhibited increased expression and reporter activity of Sox2. Correlating with these findings, YB-1 knockdown induced a differential response in the expression of genes known to be regulated by both Sox2 and YB-1 (e.g. CCND1 and ITGA6). For instance, in response to YB-1 knockdown, CCND1 and ITGA6 expression were decreased or unchanged in RU cells but paradoxically increased in RR cells. Compared to RU cells, RR cells were significantly more resistant to the suppression of mammosphere formation due to YB-1 knockdown. Importantly, mammospheres derived from parental MCF7 cells treated with YB-1 siRNA knockdown exhibited higher expression levels of SOX2 and its downstream targets.

CONCLUSIONS

To conclude, in a subset of BC cells, namely RR cells, YB-1 regulates Sox2 to coordinately maintain stemness and tumorigenic properties.

The role of cold shock domain proteins in inflammatory diseases

Cold shock domain proteins are characterized by the presence of one or more evolutionarily conserved cold shock domains, which each possess two nucleic acid-binding motifs. These proteins exert pleiotropic functions in cells via their ability to bind single-stranded RNA and/or DNA, thus allowing them to serve as transcriptional as well as translational regulators. Not only can they regulate their own expression, but they also regulate the expression of a number of pro- and anti-inflammatory cytokines, as well as cytokine receptors, making them key players in the orchestration of inflammatory processes and immune cell phenotypes. To add to their complexity, the expression of cold shock domain proteins is induced by cellular stress. At least one cold shock domain protein is actively secreted and binds to specific cell surface receptors, thereby influencing the proliferative and migratory capacity of the cell. The presence of cold shock domain proteins in the blood and/or urine of patients with cancer or inflammatory disease, as well as the identification of autoantibodies directed against these proteins make them potential targets of therapeutic interest.

Y-box binding protein 1--a prognostic marker and target in tumour therapy

Y-box binding protein 1 (YB-1) is a multifunctional protein involved in various cellular processes including both transcriptional and translational regulation of target gene expression. Significantly increased YB-1 levels have been reported in a number of human malignancies and shown to be associated with poor prognosis and disease recurrence. Indeed, YB-1 can act as a versatile oncoprotein playing an important role in tumour cell proliferation and progression. Consequently, YB-1 not only proves to be a good prognostic tumour marker, but also may be a promising emerging molecular target for the development of new therapeutical strategies. In this review, we discuss both the role of YB-1 in cancer and specifically in malignant melanoma as well as possible translations into the clinics derived thereof.

YB-1 protein: functions and regulation

The Y-box binding protein 1 (YB-1, YBX1) is a member of the family of DNA- and RNA-binding proteins with an evolutionarily ancient and conserved cold shock domain. It falls into a group of intrinsically disordered proteins that do not follow the classical rule 'one protein-one function' but introduce a novel principle stating that a disordered structure suggests many functions. YB-1 participates in a wide variety of DNA/RNA-dependent events, including DNA reparation, pre-mRNA transcription and splicing, mRNA packaging, and regulation of mRNA stability and translation. At the cell level, the multiple activities of YB-1 are manifested as its involvement in cell proliferation and differentiation, stress response, and malignant cell transformation. WIREs RNA 2014, 5:95-110. doi: 10.1002/wrna.1200 CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

YB-1 dependent oncolytic adenovirus efficiently inhibits tumor growth of glioma cancer stem like cells

Background

The brain cancer stem cell (CSC) model describes a small subset of glioma cells as being responsible for tumor initiation, conferring therapy resistance and tumor recurrence. In brain CSC, the PI3-K/AKT and the RAS/mitogen activated protein kinase (MAPK) pathways are found to be activated. In consequence, the human transcription factor YB-1, knowing to be responsible for the emergence of drug resistance and driving adenoviral replication, is phosphorylated and activated. With this knowledge, YB-1 was established in the past as a biomarker for disease progression and prognosis. This study determines the expression of YB-1 in glioblastoma (GBM) specimen in vivo and in brain CSC lines. In addition, the capacity of Ad-Delo3-RGD, an YB-1 dependent oncolytic adenovirus, to eradicate CSC was evaluated both in vitro and in vivo.

Methods

YB-1 expression was investigated by immunoblot and immuno-histochemistry. In vitro, viral replication as well as the capacity of Ad-Delo3-RGD to replicate in and, in consequence, to kill CSC was determined by real-time PCR and clonogenic dilution assays. In vivo, Ad-Delo3-RGD-mediated tumor growth inhibition was evaluated in an orthotopic mouse GBM model. Safety and specificity of Ad-Delo3-RGD were investigated in immortalized human astrocytes and by siRNA-mediated downregulation of YB-1.

Results

YB-1 is highly expressed in brain CSC lines and in GBM specimen. Efficient viral replication in and virus-mediated lysis of CSC was observed in vitro. Experiments addressing safety aspects of Ad-Delo3-RGD showed that (i) virus production in human astrocytes was significantly reduced compared to wild type adenovirus (Ad-WT) and (ii) knockdown of YB-1 significantly reduced virus replication. Mice harboring othotopic GBM developed from a temozolomide (TMZ)-resistant GBM derived CSC line which was intratumorally injected with Ad-Delo3-RGD survived significantly longer than mice receiving PBS-injections or TMZ treatment.

Conclusion

The results of this study supported YB-1 based virotherapy as an attractive therapeutic strategy for GBM treatment which will be exploited further in multimodal treatment concepts.

Grape seed procyanidin reversal of p-glycoprotein associated multi-drug resistance via down-regulation of NF-κB and MAPK/ERK mediated YB-1 activity in A2780/T cells

The expression and function of P-glycoprotein (P-gp) is associated with the phenotype of multi-drug resistance (MDR), leading chemotherapy failure of patients suffered with cancer. Grape seed procyanidin(GSP) is a natural polyphenol supplement with anti-inflammatory effect. Present study assessed a new use of GSP on the MDR reversal activity and its possible molecular mechanisms in MDR1-overpressing paclitaxel resistant ovarian cancer cells. Our results showed GSP significantly enhanced the cytotoxicity of paclitaxel and adriamycin in paclitaxel resistant A2780/T cells but its parental A2780 cells. Furthermore, GSP strongly inhibited P-gp expression by blocking MDR1 gene transcription, as well as, increased the intracellular accumulation of the P-gp substrate rhodamine-123 in A2780/T cells. Nuclear factor-κB(NF-κB) activity, IκB degradation level and NF-κB/p65 nuclear translocation induced by lipopolysaccharide (LPS) and receptor activator for nuclear factor-κB ligand (RANKL) were markedly inhibited by pre-treatment with GSP. Meanwhile, GSP inhibited MAPK/ERK pathway by decreasing the phosphorylation of ERK1/2, resulting in reduced the Y-box binding protein 1 (YB-1) activation with blocking its nuclear translocation. Moreover, the up-regulation of P-gp expression, the activation of AKT/NF-κB and MAPK/ERK pathway induced by LPS was attenuated by GSP administration. Compared with PDTC and U1026, inhibitor of NF-κB and MAPK/ERK respectively, GSP showed the same tendency of down-regulating NF-κB and MAPK/ERK mediated YB-1 activities. Thus, GSP reverses P-gp associated MDR by inhibiting the function and expression of P-gp through down-regulation of NF-κB activity and MAPK/ERK pathway mediated YB-1 nuclear translocation, offering insight into the mechanism of reversing MDR by natural polyphenol supplement compounds. GSP could be a new potential MDR reversal agent used for combination therapy with chemotherapeutics in clinic.

Mutual regulation between Raf/MEK/ERK signaling and Y-box-binding protein-1 promotes prostate cancer progression

PURPOSE

Y-box-binding protein-1 (YB-1) is known to conduct various functions related to cell proliferation, anti-apoptosis, epithelial-mesenchymal transition, and castration resistance in prostate cancer. However, it is still unknown how YB-1 affects cancer biology, especially its correlations with the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, we aimed to examine the interaction between YB-1 and the MAPK pathway in prostate cancer.

EXPERIMENTAL DESIGN

Quantitative real-time PCR, Western blotting, and co-immunoprecipitation assay were conducted in prostate cancer cells. YB-1, phosphorylated YB-1 (p-YB-1), and ERK2 protein expressions in 165 clinical specimens of prostate cancer were investigated by immunohistochemistry. YB-1, p-YB-1, and ERK2 nuclear expressions were compared with clinicopathologic characteristics and patient prognoses.

RESULTS

EGF upregulated p-YB-1, whereas MEK inhibitor (U0126, PD98059) decreased p-YB-1. Inversely, silencing of YB-1 using siRNA decreased the expression of ERK2 and phosphorylated MEK, ERK1/2, and RSK. Furthermore, YB-1 interacted with ERK2 and Raf-1 and regulated their expressions, through the proteasomal pathway. Immunohistochemical staining showed a significant correlation among the nuclear expressions of YB-1, p-YB-1, and ERK2. The Cox proportional hazards model revealed that high ERK2 expression was an independent prognostic factor [HR, 7.947; 95% confidence interval (CI), 3.527-20.508; P<0.0001].

CONCLUSION

We revealed the functional relationship between YB-1 and MAPK signaling and its biochemical relevance to the progression of prostate cancer. In addition, ERK2 expression was an independent prognostic factor. These findings suggest that both the ERK pathway and YB-1 may be promising molecular targets for prostate cancer diagnosis and therapeutics.

YB-1: oncoprotein, prognostic marker and therapeutic target?

Hanahan and Weinberg have proposed the ‘hallmarks of cancer’ to cover the biological changes required for the development and persistence of tumours [Hanahan and Weinberg (2011) Cell 144, 646–674]. We have noted that many of these cancer hallmarks are facilitated by the multifunctional protein YB-1 (Y-box-binding protein 1). In the present review we evaluate the literature and show how YB-1 modulates/regulates cellular signalling pathways within each of these hallmarks. For example, we describe how YB-1 regulates multiple proliferation pathways, overrides cell-cycle check points, promotes replicative immortality and genomic instability, may regulate angiogenesis, has a role in invasion and metastasis, and promotes inflammation. We also argue that there is strong and sufficient evidence to suggest that YB-1 is an excellent molecular marker of cancer progression that could be used in the clinic, and that YB-1 could be a useful target for cancer therapy.

MAPK and PI3K/AKT mediated YB-1 activation promotes melanoma cell proliferation which is counteracted by an autoregulatory loop

Y-box binding protein 1 (YB-1) is an oncogenic transcription and translation factor and is overexpressed in several types of cancer. Our previous data showed that YB-1 is upregulated and translocated to the nucleus during melanoma progression and that YB-1 is an important transcription factor regulating proliferation, survival, migration, invasion and chemosensitivity of melanoma cells. It has been suggested that YB-1 is activated and translocated to the nucleus after S102-phosphorylation in the DNA binding domain. In this study, we show that activation of YB-1 by S102-phosphorylation and nuclear translocation is increased during melanoma progression using a human tissue microarray with 100 melanocytic lesions. Furthermore, we analysed the mechanisms governing the expression and activity of YB-1 in melanoma cells. We show that the PI3K/AKT and p53 signalling, growth factors and chemotherapeutic agents increase YB-1 promoter activity. This, however, resulted in no or only modest increase in YB-1 protein expression. We show that the MAPK and PI3K/AKT signalling pathways, both activated in melanoma cells, as well as p53 overexpression increase YB-1 S102-phosphorylation, whereas NFκB signalling inhibits phosphorylation. Overexpression of YB-1 in melanoma cells inhibits translation efficiency and by this proliferation and survival of melanoma cells indicating that there is an autoregulatory loop restricting YB-1 protein expression. These data suggest that there is a tightly regulated feedback mechanism regulating YB-1 expression and activation, necessary for proper cell cycle progression of melanoma cells.

Y-box binding protein 1 and RNase UK114 mediate monocyte chemoattractant protein 1 mRNA stability in vascular smooth muscle cells

Monocyte chemoattractant protein 1 (MCP-1) plays a pivotal role in many inflammatory processes, including the progression of atherosclerosis and the response of the arterial wall to injury. We previously demonstrated that dexamethasone (Dex) inhibits MCP-1 mRNA accumulation in smooth muscle cells by decreasing its half-life. The effect of Dex was dependent upon the glucocorticoid receptor (GR) and independent of new transcription. Using RNA affinity and column chromatography, we have identified two proteins involved in regulating MCP-1 mRNA stability: Y-box binding protein 1 (YB-1), a multifunctional DNA/RNA-binding protein, and endoribonuclease UK114 (UK). By immunoprecipitation, YB and GR formed a complex present in equal amounts in extracts from untreated and Dex-treated cells. YB-1, UK, and GR small interfering RNA (siRNA) substantially inhibited the effect of Dex on MCP-1 mRNA accumulation. In addition, YB-1 antibody blocked the degradation of MCP-1 mRNA by cytoplasmic extracts from the Dex-treated cells. The degradative activity of extracts immunoprecipitated with antibodies to either YB-1 or GR was blocked with UK antibody. UK did not degrade MCP-1 mRNA; however, upon addition to nondegrading control extracts, it rapidly degraded MCP-1 mRNA. These studies define new roles for GR, YB-1, and UK in the formation of a molecular complex that degrades MCP-1 mRNA.

Y-box-binding protein 1 (YB-1) and its functions

This review describes the structure and functions of Y-box binding protein 1 (YB-1) and its homologs. Interactions of YB-1 with DNA, mRNAs, and proteins are considered. Data on the participation of YB-1 in DNA reparation and transcription, mRNA splicing and translation are systematized. Results on interactions of YB-1 with cytoskeleton components and its possible role in mRNA localization are discussed. Data on intracellular distribution of YB-1, its redistribution between the nucleus and the cytoplasm, and its secretion and extracellular functions are summarized. The effect of YB-1 on cell differentiation, its involvement in extra- and intracellular signaling pathways, and its role in early embryogenesis are described. The mechanisms of regulation of YB-1 expression in the cell are presented. Special attention is paid to the involvement of YB-1 in oncogenic cell transformation, multiple drug resistance, and dissemination of tumors. Both the oncogenic and antioncogenic activities of YB-1 are reviewed. The potential use of YB-1 in diagnostics and therapy as an early cancer marker and a molecular target is discussed.

The role of MAPK in drug-induced kidney injury

This paper focuses on the role that mitogen-activated protein kinases (MAPKs) play in drug-induced kidney injury. The MAPKs, of which there are four major classes (ERK, p38, JNK, and ERK5/BMK), are signalling cascades which have been found to be broadly conserved across a wide variety of organisms. MAPKs allow effective transmission of information from the cell surface to the cytosolic or nuclear compartments. Cross talk between the MAPKs themselves and with other signalling pathways allows the cell to modulate responses to a wide variety of external stimuli. The MAPKs have been shown to play key roles in both mediating and ameliorating cellular responses to stress including xenobiotic-induced toxicity. Therefore, this paper will discuss the specific role of the MAPKs in the kidney in response to injury by a variety of xenobiotics and the potential for therapeutic intervention at the level of MAPK signalling across different types of kidney disease.

Cold-shock-domain protein A (CSDA) contributes posttranscriptionally to gonadotropin-releasing hormone-regulated expression of Egr1 and indirectly to Lhb

Gonadotropin-releasing hormone (GnRH), a hypothalamic neurohormone, regulates transcription of Lhb in gonadotrophs indirectly through transient induction and accumulation of EGR1, a zinc finger transcription factor. AlphaT3 and LbetaT2 cell lines model gonadotrophs at two distinct stages of development, prenatal and postnatal expression of Lhb. Although GnRH induces EGR1 in both cell lines, the levels of the DNA-binding protein are lower and disappear more quickly in alphaT3 than in LbetaT2 cells. Herein we show that overexpression of Egr1 in alphaT3 cells rescues activity of a transfected LHB promoter-reporter, suggesting that its transcription is dependent on EGR1 crossing a critical concentration threshold. We also show that Csda, a gene that encodes an RNA-binding protein and is a member of the cold-shock-domain (CSD) family, is expressed at higher levels in LbetaT2 compared to alphaT3 cells. Transient expression studies indicate that at least one Csd element, residing in the 3' untranslated region of Egr1 mRNA, increases activity of a chimeric pGL3 luciferase reporter vector in LbetaT2 cells. Additional experiments indicate that CSDA physically interacts with Egr1 mRNA. Furthermore, siRNA-mediated reduction of endogenous Csda mRNA attenuates GnRH regulation of a transiently transfected LHB reporter vector. Taken together, these studies suggest that CSDA contributes posttranscriptionally to GnRH-regulated expression of Egr1, thereby enabling the transcription factor to cross a critical concentration threshold necessary for maximal accumulation of Lhb mRNA in response to the neurohormone.

Expression of Y-box-binding protein YB-1 allows stratification into long- and short-term survivors of head and neck cancer patients

Background:

Histology-based classifications and clinical parameters of head and neck squamous cell carcinoma (HNSCC) are limited in their clinical capacity to provide information on prognosis and treatment choice of HNSCC. The primary aim of this study was to analyse Y-box-binding protein-1 (YB-1) protein expression in different grading groups of HNSCC patients, and to correlate these findings with the disease-specific survival (DSS).

Methods:

We investigated the expression and cellular localisation of the oncogenic transcription/translation factor YB-1 by immunohistochemistry on tissue micro arrays in a total of 365 HNSCC specimens and correlated expression data with clinico-pathological parameters including DSS.

Results:

Compared with control tissue from healthy individuals, a significantly (P<0.01) increased YB-1 protein expression was observed in high-grade HNSCC patients. By univariate survival data analysis, HNSCC patients with elevated YB-1 protein expression had a significantly (P<0.01) decreased DSS. By multivariate Cox regression analysis, high YB-1 expression and nuclear localisation retained its significance as a statistically independent (P<0.002) prognostic marker for DSS. Within grade 2 group of HNSCC patients, a subgroup defined by high nuclear and cytoplasmic YB-1 levels (co-expression pattern) in the cells of the tumour invasion front had a significantly poorer 5-year DSS rate of only 38% compared with overall 55% for grade 2 patients. Vice versa, the DSS rate was markedly increased to 74% for grade 2 cancer patients with low YB-1 protein expression at the same localisation.

Conclusion:

Our findings point to the fact that YB-1 expression in combination with histological classification in a double stratification strategy is superior to classical grading in the prediction of tumour progression in HNSCC.

Cold shock Y-box protein-1 participates in signaling circuits with auto-regulatory activities

The cold shock protein Y-box (YB) binding-1 is an example of a highly regulated protein with pleiotropic functions. Besides activities as a transcription factor in the nucleus or regulator of translation in the cytoplasm, recent findings indicate extracellular effects and secretion via a non-classical secretion pathway. This review summarizes regulatory pathways in which YB-1 participates, all iterating auto-regulatory loops. Schematics are developed that elucidate the cold shock protein activities in (i) fine-tuning its own expression level following platelet-derived growth factor-B-, thrombin- or interferon-γ-dependent signaling, (ii) as a component of the messenger ribonucleoprotein (mRNP) complex for interleukin-2 synthesis in T-cell commitment/activation, (iii) pro-fibrogenic cell phenotypic changes mediated by transforming growth factor-β, and (iv) receptor Notch-3 cleavage and signal transduction. Emphasis is put forward on subcellular protein translocation mechanisms and underlying signaling pathways. These have mostly been analysed in cell culture systems and rarely in experimental models. In sum, YB-1 seems to fulfill a pacemaker role in diverse diseases, both inflammatory/pro-fibrogenic as well as tumorigenic. A clue towards potential intervention strategies may reside in the understanding of the outlined auto-regulatory loops and means to interfere with cycling pathways.

Role of cold shock Y-box protein-1 in inflammation, atherosclerosis and organ transplant rejection

Chemokines (chemoattractant cytokines) are crucial regulators of immune cell extravasation from the bloodstream into inflamed tissue. Dysfunctional regulation and perpetuated chemokine gene expression are linked to progressive chronic inflammatory diseases and, in respect to transplanted organs, may trigger graft rejection. RANTES (regulated upon activation, normal T cell expressed and secreted (also known as CCL5)) is a model chemokine with relevance in numerous inflammatory diseases where the innate immune response predominates. Transcription factor Y-box binding protein-1 (YB-1) serves as a trans-regulator of CCL5 gene transcription in vascular smooth muscle cells and leucocytes. This review provides an update on YB-1 as a mediator of inflammatory processes and focuses on the role of YB-1 in CCL5 expression in diseases with monocytic cell infiltrates, albeit acute or chronic. Paradigms of such diseases encompass atherosclerosis and transplant rejection where cold shock protein YB-1 takes a dominant role in transcriptional regulation.

Y-box binding protein-1 mediates profibrotic effects of calcineurin inhibitors in the kidney

The immunosuppressive calcineurin inhibitors (CNIs) cyclosporine A (CsA) and tacrolimus are widely used in transplant organ recipients, but in the kidney allograft, they may cause tubulointerstitial as well as mesangial fibrosis, with TGF-β believed to be a central inductor. In this study, we report that the cold-shock protein Y-box binding protein-1 (YB-1) is a TGF-β independent downstream effector in CsA- as well as in tacrolimus- but not in rapamycin-mediated activation of rat mesangial cells (rMCs). Intracellular content of YB-1 is several-fold increased in MCs following CNI treatment in vitro and in vivo in mice. This effect ensues in a time-dependent manner, and the operative concentration range encompasses therapeutically relevant doses for CNIs. The effect of CNI on cellular YB-1 content is abrogated by specific blockade of translation, whereas retarding the transcription remains ineffective. The activation of rMCs by CNIs is accomplished by generation of reactive oxygen species. In contrast to TGF-β-triggered reactive oxygen species generation, hydrogen peroxide especially could be identified as a potent inductor of YB-1 accumulation. In line with this, hindering TGF-β did not influence CNI-induced YB-1 upregulation, whereas ERK/Akt pathways are involved in CNI-mediated YB-1 expression. CsA-induced YB-1 accumulation results in mRNA stabilization and subsequent generation of collagen. Our results provide strong evidence for a CNI-dependent induction of YB-1 in MCs that contributes to renal fibrosis via regulation of its own and collagen translation.

Upregulation of mdr1 gene is related to activation of the MAPK/ERK signal transduction pathway and YB-1 nuclear translocation in B-cell lymphoma

OBJECTIVE

Multidrug resistance (MDR) in human B-cell lymphoma constitutes a major obstacle to the effectiveness of chemotherapy. The aim of this study was to investigate the molecular mechanism of MDR in B-cell lymphoma.

MATERIALS AND METHODS

The B-cell lymphoma MDR sublines were developed by exposing the parental Daudi cells to stepwise increasing concentrations of doxorubicin. Interaction of Y-box binding protein-1 (YB-1) with the Y-box motif of the mdr1 gene promoters was studied by electrophoretic mobility shift assay. The effects of YB-1 on mdr1 promoter activity were examined by luciferase assay. After silencing of YB-1 gene by shRNA, the role of YB-1 nuclear translocation in the formation of induced MDR was examined. Expression of mdr1 and YB-1 was examined further after Daudi cells were pretreated with mitogen-activated protein kinase (MAPK) inhibitor PD98059 for 1 hour.

RESULTS

Doxorubicin-resistant sublines was generated from the Daudi cell line by stepwise selection in doxorubicin. We found that acquisition of MDR is associated with enhanced YB-1 nuclear translocation and MAPK/extracellular signal-regulated kinase (ERK) activity. Electrophoretic mobility shift assay revealed that doxorubicin increased binding of YB-1 to the Y-box of mdr1 promoter. Luciferase reporter assays demonstrated that the Y-box region is essential for YB-1 regulation of mdr1 expression. The introduction of exogenous YB-1 shRNA into Daudi cells resulted in decreased levels of the expression of mdr1 gene and P-glycoprotein induced by doxorubicin. When Daudi cells were pretreated with MAPK inhibitor PD98059, the phosphorylation of ERK was effectively inhibited as well as the nuclear translocation of YB-1 and the expression of mdr1 gene.

CONCLUSION

Doxorubicin can increase expression of mdr1/P-glycoprotein through activating MAPK/ERK transduction pathway, then increasing expression of YB-1, inducing YB-1 nuclear translocation, and enhancing DNA-binding activity of YB-1.

Assessment of downstream effectors of BCR/ABL protein tyrosine kinase using combined proteomic approaches

Leukaemic transformation is frequently associated with the aberrant activity of a protein tyrosine kinase (PTK). As such it is of clinical relevance to be able to map the effects of these leukaemogenic PTKs on haemopoietic cells at the level of phosphorylation modulation. In this paradigm study we have employed a range of proteomic approaches to analyse the effects of one such PTK, BCR/ABL. We have employed phosphoproteome enrichment techniques allied to peptide and protein quantification to identify proteins and pathways involved in cellular transformation. Amongst the proteins shown to be regulated at the post-translational level were cofilin, an actin-severing protein thus linked to altered motility and Cbl an E3 ubiquitin ligase integrally linked to the control of tyrosine kinase signalling (regulated by 5 and 6 PTKs respectively). The major class of proteins identified however were molecular chaperones. We also showed that HSP90 phosphorylation is altered by BCR/ABL action and that HSP90 plays a crucial role in oncogene stability. Further investigation with another six leukaemogenic PTKs demonstrates that this HSP90 role in oncogene stability appears to be a common phenomenon in a range of leukaemias. This opens up the potential opportunity to treat different leukaemias with HSP90 inhibitors.

Identification of Y-box binding protein 1 as a core regulator of MEK/ERK pathway-dependent gene signatures in colorectal cancer cells

Transcriptional signatures are an indispensible source of correlative information on disease-related molecular alterations on a genome-wide level. Numerous candidate genes involved in disease and in factors of predictive, as well as of prognostic, value have been deduced from such molecular portraits, e.g. in cancer. However, mechanistic insights into the regulatory principles governing global transcriptional changes are lagging behind extensive compilations of deregulated genes. To identify regulators of transcriptome alterations, we used an integrated approach combining transcriptional profiling of colorectal cancer cell lines treated with inhibitors targeting the receptor tyrosine kinase (RTK)/RAS/mitogen-activated protein kinase pathway, computational prediction of regulatory elements in promoters of co-regulated genes, chromatin-based and functional cellular assays. We identified commonly co-regulated, proliferation-associated target genes that respond to the MAPK pathway. We recognized E2F and NFY transcription factor binding sites as prevalent motifs in those pathway-responsive genes and confirmed the predicted regulatory role of Y-box binding protein 1 (YBX1) by reporter gene, gel shift, and chromatin immunoprecipitation assays. We also validated the MAPK-dependent gene signature in colorectal cancers and provided evidence for the association of YBX1 with poor prognosis in colorectal cancer patients. This suggests that MEK/ERK-dependent, YBX1-regulated target genes are involved in executing malignant properties.

Suppression of Her2/neu expression through ILK inhibition is regulated by a pathway involving TWIST and YB-1

In a previous study it was found that the therapeutic effects of QLT0267, a small molecule inhibitor of integrin-linked kinase (ILK), were influenced by Her2/neu expression. To understand how inhibition or silencing of ILK influences Her2/neu expression, Her2/neu signaling was evaluated in six Her2/neu-positive breast cancer cell lines (LCC6^Her2, MCF7^Her2, SKBR3, BT474, JIMT-1 and KPL-4). Treatment with QLT0267 engendered suppression (32–87%) of total Her2/neu protein in these cells. Suppression of Her2/neu was also observed following small interfering RNA-mediated silencing of ILK expression. Time course studies suggest that ILK inhibition or silencing caused transient decreases in P-AKT^ser473, which were not temporally related to Her2/neu downregulation. Attenuation of ILK activity or expression was, however, associated with decreases in YB-1 (Y-box binding protein-1) protein and transcript levels. YB-1 is a known transcriptional regulator of Her2/neu expression, and in this study it is demonstrated that inhibition of ILK activity using QLT0267 decreased YB-1 promoter activity by 50.6%. ILK inhibition was associated with changes in YB-1 localization, as reflected by localization of cytoplasmic YB-1 into stress granules. ILK inhibition also suppressed TWIST (a regulator of YB-1 expression) protein expression. To confirm the role of ILK on YB-1 and TWIST, cells were engineered to overexpress ILK. This was associated with a fourfold increase in the level of YB-1 in the nucleus, and a 2- and 1.5-fold increase in TWIST and Her2/neu protein levels, respectively. Taken together, these data indicate that ILK regulates the expression of Her2/neu through TWIST and YB-1, lending support to the use of ILK inhibitors in the treatment of aggressive Her2/neu-positive tumors.

A highly conserved molecular switch binds MSY-3 to regulate myogenin repression in postnatal muscle

Myogenin is the dominant transcriptional regulator of embryonic and fetal muscle differentiation and during maturation is profoundly down-regulated. We show that a highly conserved 17-bp DNA cis-acting sequence element located upstream of the myogenin promoter (myogHCE) is essential for postnatal repression of myogenin in transgenic animals. We present multiple lines of evidence supporting the idea that repression is mediated by the Y-box protein MSY-3. Electroporation in vivo shows that myogHCE and MSY-3 are required for postnatal repression. We further show that, in the C2C12 cell culture system, ectopic MSY-3 can repress differentiation, while reduced MSY-3 promotes premature differentiation. MSY-3 binds myogHCE simultaneously with the homeodomain protein Pbx in postnatal innervated muscle. We therefore propose a model in which the myogHCE motif operates as a switch by specifying opposing functions; one that was shown previously is regulated by MyoD and Pbx and it specifies a chromatin opening, gene-activating function at the time myoblasts begin to differentiate; the other includes MYS-3 and Pbx, and it specifies a repression function that operates during and after postnatal muscle maturation in vivo and in myoblasts before they begin to differentiate.

Unidirectional crosstalk between Bcl-xL and Bcl-2 enhances the angiogenic phenotype of endothelial cells

Expression of Bcl-x(L) correlates with the clinical outcomes of patients with cancer. While the role of Bcl-2 in angiogenesis is becoming increasingly evident, the function of Bcl-x(L) in angiogenesis is unclear. Here, we showed that epidermal growth factor (EGF) induces in vitro capillary sprouting and Bcl-x(L) expression in primary endothelial cells. Bcl-x(L)-transduced human dermal microvascular endothelial cells (HDMEC-Bcl-x(L)), but not empty vector control cells, spontaneously organize into capillary-like sprouts. Searching for a mechanism to explain these responses, we observed that Bcl-x(L) induced expression of the pro-angiogenic chemokines CXC ligand-1 (CXCL1) and CXC ligand-8 (CXCL8), and that blockade of CXC receptor-2 (CXCR2) signaling inhibited spontaneous sprouting of HDMEC-Bcl-x(L). Bcl-x(L) led to Bcl-2 upregulation, but Bcl-2 did not upregulate Bcl-x(L), suggesting the existence of a unidirectional crosstalk from Bcl-x(L) to Bcl-2. EGF and Bcl-x(L) activate the mitogen-activated protein kinase/ERK pathway resulting in upregulation of vascular endothelial growth factor (VEGF), a known inducer of Bcl-2 in endothelial cells. Inhibition of VEGF receptor signaling in HDMEC-Bcl-x(L) prevented Bcl-2 upregulation and demonstrated the function of a VEGF-mediated autocrine loop. Bcl-2 downregulation by RNAi blocked CXCL1 and CXCL8 expression downstream of Bcl-x(L), and markedly decreased angiogenesis in vivo. We conclude that Bcl-x(L) functions as a pro-angiogenic signaling molecule controlling Bcl-2 and VEGF expression. These results emphasize a complex interplay between Bcl-2 family members beyond their classical roles in apoptosis.