Differential regulation of chemokine CCL5 expression in monocytes/macrophages and renal cells by Y-box protein-1

Y-box binding protein 1: A critical target for understanding and treating cardiovascular disease

Cardiovascular diseases (CVDs) remain a significant public health burden, characterized by escalating morbidity and mortality rates and demanding novel therapeutic approaches. Cold shock protein Y-box binding protein 1 (YB-1), a highly conserved RNA/DNA-binding protein, has emerged as a pivotal regulator in various pathophysiological processes, including CVDs. YB-1 exerts pleiotropic functions by modulating gene transcription, pre-mRNA splicing, mRNA translation, and stability. The expression and function of YB-1 are intricately regulated by its subcellular localization, post-translational modifications, upstream regulatory signals. YB-1 plays a multifaceted role in CVDs, influencing inflammation, oxidative stress, cell proliferation, apoptosis, phenotypic switching of smooth muscle cells, and mitochondrial dysfunction. However, the regulation of YB-1 expression and function in CVDs is complex and context-dependent, exhibiting divergent effects even in the same disease across different cell types or at disease stages. This review comprehensively explores the structure, regulation, and functional significance of YB-1 in CVDs. We delve into the transcriptional and translational control mechanisms of YB-1, as well as its post-translational modifications. Furthermore, we elucidate the upstream signaling pathways that influence YB-1 expression, with a particular emphasis on non-coding RNAs and specific upstream molecules. Finally, we systematically examine the role of YB-1 in CVDs, summarizing its expression patterns, regulatory mechanisms, and therapeutic potential as a promising target for novel therapeutic interventions. By providing a comprehensive overview of YB-1's involvement in CVDs, this review aims to stimulate further research and facilitate the development of targeted therapies to improve cardiovascular health.

"Unveiling the impacts of climatic cold events on the cardiovascular health in animal models"

Climate change is increasingly driving extreme weather events, leading to drastic temperature fluctuations worldwide. While overall temperatures rise, many regions are simultaneously experiencing severe cold spells that threaten the health of human populations, especially to vulnerable populations including the elderly and those with pre-existing conditions. Exposure to cold stress triggers significant physiological and biochemical disruptions. As cardiovascular diseases (CVDs) rank among the leading causes of global morbidity and mortality, the exacerbation of these conditions by cold exposure underscores critical public health challenges. The complex pathophysiological processes in cold-induced CVDs require careful analysis at an organ-system level, making animal models an ideal tool for replicating human physiological and molecular responses in a controlled environment. However, a detailed mechanism linking cold exposure and cardiovascular dysfunction remains incompletely understood, particularly in the context of animal models. Therefore, this comprehensive review aims to address and analyze from traditional rodent models to less conventional ruminants, broilers, canines, and primate animal models to understand cold stress-induced CVDs, with an extensive account of the potential molecular mechanisms and pathways such as oxidative stress, inflammation, vasomotor dysfunction, and apoptosis, along with emerging roles of cold shock proteins (CSPs), etc. We also delve into various potential therapeutic approaches and preventive measures in cold stress conditions. In conclusion, this review is the first to comprehensively address the underexplored cardiovascular complications arising from cold stress and their underlying mechanisms, particularly using animal models. Furthermore, it provides a foundation for advancing the development of more effective and targeted therapies through translational research.

Role of chemokine receptors in transplant rejection and graft-versus-host disease

Organ transplantation increases life expectancy and improves the quality of life of patients experiencing specific conditions such as terminal organ failure. Despite matching efforts between donor and recipient, immune activation can interfere with allograft survival after transplantation if immunosuppression is not used. With both innate and adaptive responses, this is a complicated immunological process. This can lead to organ rejection, or graft-versus-host disease (GVHD), depending on the origin of the immune response. Inflammatory factors, such as chemokine receptors and their ligands, are involved in a wide variety of immunological processes, including modulating transplant rejection or GVHD, therefore, chemokine biology has been a major focus of transplantation studies. These molecules attract circulating peripheral leukocytes to infiltrate into the allograft and facilitate dendritic and T cell trafficking between lymph nodes and the graft during the allogeneic response. In this chapter, we will review the most relevant chemokine receptors such as CXCR3 and CCR5, among others, and their ligands involved in the process of allograft rejection for solid organ transplantation and graft-versus-host disease in the context of hematopoietic cell transplantation.

Glomerular-tubular crosstalk via cold shock Y-box binding protein-1 in the kidney

Glomerular-tubular crosstalk within the kidney has been proposed, but the paracrine signals enabling this remain largely unknown. The cold-shock protein Y-box binding protein 1 (YBX1) is known to regulate inflammation and kidney diseases but its role in podocytes remains undetermined. Therefore, we analyzed mice with podocyte specific Ybx1 deletion (Ybx1ΔPod). Albuminuria was increased in unchallenged Ybx1ΔPod mice, which surprisingly was associated with reduced glomerular, but enhanced tubular damage. Tubular toll-like receptor 4 (TLR4) expression, node-like receptor protein 3 (NLRP3) inflammasome activation and kidney inflammatory cell infiltrates were all increased in Ybx1ΔPod mice. In vitro, extracellular YBX1 inhibited NLRP3 inflammasome activation in tubular cells. Co-immunoprecipitation, immunohistochemical analyses, microscale cell-free thermophoresis assays, and blunting of the YBX1-mediated TLR4-inhibition by a unique YBX1-derived decapeptide suggests a direct interaction of YBX1 and TLR4. Since YBX1 can be secreted upon post-translational acetylation, we hypothesized that YBX1 secreted from podocytes can inhibit TLR4 signaling in tubular cells. Indeed, mice expressing a non-secreted YBX1 variant specifically in podocytes (Ybx1PodK2A mice) phenocopied Ybx1ΔPod mice, demonstrating a tubular-protective effect of YBX1 secreted from podocytes. Lipopolysaccharide-induced tubular injury was aggravated in Ybx1ΔPod and Ybx1PodK2A mice, indicating a pathophysiological relevance of this glomerular-tubular crosstalk. Thus, our data show that YBX1 is physiologically secreted from podocytes, thereby negatively modulating sterile inflammation in the tubular compartment, apparently by binding to and inhibiting tubular TLR4 signaling. Hence, we have uncovered an YBX1-dependent molecular mechanism of glomerular-tubular crosstalk.

Excessive sodium chloride ingestion promotes inflammation and kidney fibrosis in aging mice

In aging kidneys, a decline of function resulting from extracellular matrix (ECM) deposition and organ fibrosis is regarded as "physiological." Whether a direct link between high salt intake and fibrosis in aging kidney exists autonomously from arterial hypertension is unclear. This study explores kidney intrinsic changes (inflammation, ECM derangement) induced by a high-salt diet (HSD) in a murine model lacking arterial hypertension. The contribution of cold shock Y-box binding protein (YB-1) as a key orchestrator of organ fibrosis to the observed differences is determined by comparison with a knockout strain (Ybx1ΔRosaERT+TX). Comparisons of tissue from mice fed with normal-salt diet (NSD, standard chow) or high-salt diet (HSD, 4% NaCl in chow; 1% NaCl in water) for up to 16 mo revealed that with HSD tubular cell numbers decrease and tubulointerstitial scarring [periodic acid-Schiff (PAS), Masson's trichrome, Sirius red staining] prevails. In Ybx1ΔRosaERT+TX animals tubular cell damage, a loss of cell contacts with profound tubulointerstitial alterations, and tubular cell senescence was seen. A distinct tubulointerstitial distribution of fibrinogen, collagen type VI, and tenascin-C was detected under HSD, transcriptome analyses determined patterns of matrisome regulation. Temporal increase of immune cell infiltration was seen under HSD of wild type, but not Ybx1ΔRosaERT+TX animals. In vitro Ybx1ΔRosaERT+TX bone marrow-derived macrophages exhibited a defect in polarization (IL-4/IL-13) and abrogated response to sodium chloride. Taken together, HSD promotes progressive kidney fibrosis with premature cell aging, ECM deposition, and immune cell recruitment that is exacerbated in Ybx1ΔRosaERT+TX animals.NEW & NOTEWORTHY Short-term experimental studies link excessive sodium ingestion with extracellular matrix accumulation and inflammatory cell recruitment, yet long-term data are scarce. Our findings with a high-salt diet over 16 mo in aging mice pinpoints to a decisive tipping point after 12 mo with tubular stress response, skewed matrisome transcriptome, and immune cell infiltration. Cell senescence was aggravated in knockout animals for cold shock Y-box binding protein (YB-1), suggesting a novel protective protein function.

DNA binding protein YB-1 is a part of the neutrophil extracellular trap mediation of kidney damage and cross-organ effects

Open-heart surgery is associated with high morbidity, with acute kidney injury (AKI) being one of the most commonly observed postoperative complications. Following open-heart surgery, in an observational study we found significantly higher numbers of blood neutrophils in a group of 13 patients with AKI compared to 25 patients without AKI (AKI: 12.9±5.4 ×109 cells/L; non-AKI: 10.1±2. 9 ×109 cells/L). Elevated serum levels of neutrophil extracellular trap (NETs) components, such as dsDNA, histone 3, and DNA binding protein Y-box protein (YB)-1, were found within the first 24 hours in patients who later developed AKI. We could demonstrate that NET formation and hypoxia triggered the release of YB-1, which was subsequently shown to act as a mediator of kidney tubular damage. Experimentally, in two models of AKI mimicking kidney hypoperfusion during cardiac surgery (bilateral ischemia/reperfusion (I/R) and systemic lipopolysaccharide (LPS) administration), a neutralizing YB-1 antibody was administered to mice. In both models, prophylactic YB-1 antibody administration significantly reduced the tubular damage (damage score range 1-4, the LPS model: non-specific IgG control, 0.92±0.23; anti-YB-1 0.65±0.18; and in the I/R model: non-specific IgG control 2.42±0.23; anti-YB-1 1.86±0.44). Even in a therapeutic, delayed treatment model, antagonism of YB-1 ameliorated AKI (damage score, non-specific IgG control 3.03±0.31; anti-YB-1 2.58±0.18). Thus, blocking extracellular YB-1 reduced the effects induced by hypoxia and NET formation in the kidney and significantly limited AKI, suggesting that YB-1 is part of the NET formation process and an integral mediator of cross-organ effects.

RNA-binding proteins and their role in kidney disease

RNA-binding proteins (RBPs) are of fundamental importance for post-transcriptional gene regulation and protein synthesis. They are required for pre-mRNA processing and for RNA transport, degradation and translation into protein, and can regulate every step in the life cycle of their RNA targets. In addition, RBP function can be modulated by RNA binding. RBPs also participate in the formation of ribonucleoprotein complexes that build up macromolecular machineries such as the ribosome and spliceosome. Although most research has focused on mRNA-binding proteins, non-coding RNAs are also regulated and sequestered by RBPs. Functional defects and changes in the expression levels of RBPs have been implicated in numerous diseases, including neurological disorders, muscular atrophy and cancers. RBPs also contribute to a wide spectrum of kidney disorders. For example, human antigen R has been reported to have a renoprotective function in acute kidney injury (AKI) but might also contribute to the development of glomerulosclerosis, tubulointerstitial fibrosis and diabetic kidney disease (DKD), loss of bicaudal C is associated with cystic kidney diseases and Y-box binding protein 1 has been implicated in the pathogenesis of AKI, DKD and glomerular disorders. Increasing data suggest that the modulation of RBPs and their interactions with RNA targets could be promising therapeutic strategies for kidney diseases.

Role of YB-1 Protein in Inflammation

This review discusses the role of the multifunctional DNA/RNA-binding protein YB-1 in inflammation. YB-1 performs multiple functions in the cell depending on its location: it acts as transcriptional factor for many genes in the nucleus, regulates translation and stability of mRNA in the cytoplasm, and becomes a paracrine factor when secreted from the cells. The review presents the data on the YB-1-mediated regulation of inflammation-associated genes, as well as results of studies on the YB-1 role in animal model of various inflammatory diseases, such as glomerulonephritis, tubulointerstitial fibrosis, and bacterial sepsis, and on the YB-1 expression in different human diseases associated with inflammatory processes in kidney, liver, and endometrium. The last section of the review presents several approaches to the regulation of YB-1 with small molecules in the treatment of inflammatory diseases.

CCL5 secreted by luminal B breast cancer cells induces polarization of M2 macrophages through activation of MEK/STAT3 signaling pathway via CCR5

In humans, breast cancer affects a large number of females and causes a high rate of mortality worldwide. Chemokine (C-C motif) ligand 5 (CCL5) is one of the cytokines that is highly correlated to the invasive and metastatic stages of breast cancer. Our previous study has suggested the prognostic value of CCL5 expression in luminal B (HER2 - ) breast cancer. In this study, CCL5 expression was upregulated or knockdown in a luminal B breast cancer cell line, ZR7530. Further, we elucidated the effects of CCL5 on the differentiation of THP-1 monocytes into M2 macrophages. Overexpression of CCL5 affected THP-1-M2 differentiation and phosphorylation of MEK1/2, ERK1/2, and STAT2 in the cocultivated cell lines. We report that the knockdown of CCR5, a receptor of CCL5 in THP-1, inhibited the effect of ZR7530 in promoting THP-1-M2 differentiation. Furthermore, our data revealed that the inhibition of MEK1/2 and STAT3 in THP-1 cells produced equivalent results similar to those of CCL5 knockdown. In summary, we revealed the role of CCL5 in the polarization of M2 macrophages. Furthermore, we studied its interaction with CCR5 and MEK/STAT3 signaling members. These targets could be used as key regulatory members in human breast cancer therapy.

Novel Insights into YB-1 Signaling and Cell Death Decisions

YB-1 belongs to the evolutionarily conserved cold-shock domain protein family of RNA binding proteins. YB-1 is a well-known transcriptional and translational regulator, involved in cell cycle progression, DNA damage repair, RNA splicing, and stress responses. Cell stress occurs in many forms, e.g., radiation, hyperthermia, lipopolysaccharide (LPS) produced by bacteria, and interferons released in response to viral infection. Binding of the latter factors to their receptors induces kinase activation, which results in the phosphorylation of YB-1. These pathways also activate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a well-known transcription factor. NF-κB is upregulated following cellular stress and orchestrates inflammatory responses, cell proliferation, and differentiation. Inflammation and cancer are known to share common mechanisms, such as the recruitment of infiltrating macrophages and development of an inflammatory microenvironment. Several recent papers elaborate the role of YB-1 in activating NF-κB and signaling cell survival. Depleting YB-1 may tip the balance from survival to enhanced apoptosis. Therefore, strategies that target YB-1 might be a viable therapeutic option to treat inflammatory diseases and improve tumor therapy.

YB-1 Interferes with TNFα-TNFR Binding and Modulates Progranulin-Mediated Inhibition of TNFα Signaling

Inflammation and an influx of macrophages are common elements in many diseases. Among pro-inflammatory cytokines, tumor necrosis factor α (TNFα) plays a central role by amplifying the cytokine network. Progranulin (PGRN) is a growth factor that binds to TNF receptors and interferes with TNFα-mediated signaling. Extracellular PGRN is processed into granulins by proteases released from immune cells. PGRN exerts anti-inflammatory effects, whereas granulins are pro-inflammatory. The factors coordinating these ambivalent functions remain unclear. In our study, we identify Y-box binding protein-1 (YB-1) as a candidate for this immune-modulating activity. Using a yeast-2-hybrid assay with YB-1 protein as bait, clones encoding for progranulin were selected using stringent criteria for strong interaction. We demonstrate that at physiological concentrations, YB-1 interferes with the binding of TNFα to its receptors in a dose-dependent manner using a flow cytometry-based binding assay. We show that YB-1 in combination with progranulin interferes with TNFα-mediated signaling, supporting the functionality with an NF-κB luciferase reporter assay. Together, we show that YB-1 displays immunomodulating functions by affecting the binding of TNFα to its receptors and influencing TNFα-mediated signaling via its interaction with progranulin.

Altered monocytic phenotypes are linked with systemic inflammation and may be linked to mortality in dialysis patients

The major causes for increased morbidity and mortality among chronic kidney disease patients are cardiovascular diseases and infection. A causal link between an activated immune system and aggravated atherosclerosis has been postulated that skews the system towards inflammatory responses. Previously, we demonstrated a positive association of pro-inflammatory cytokines with monocytic Y-box binding protein-1 (YB-1) expression and vessel wall infiltration in hemodialysis patients. Here, we question whether the responsiveness and cytokine repertoire of monocytes is altered by pre-activation and how this correlates with survival. EDTA whole blood from hemodialysis patients (n = 45) and healthy controls (n = 34) was collected and leukocytes challenged with LPS. The distribution of monocyte subsets, YB-1_acetyl content, and serum cytokine levels were determined. Compared to controls, dialysis patients have fewer classical (Mo1) and more intermediate (Mo2) and non-classical (Mo3) monocytes. In response to LPS, the Mo2 subset significantly increases (p < 0.001) in control subjects, but not in hemodialysis patients; increased CD86 expression indicates a positive response to LPS. Based on the changes within Mo2, subjects could be classified as responders or non-responders: 60% non-responders were seen in the dialysis cohort versus only 35% among healthy controls. YB-1 acetylation is higher in dialysis patients, independent of LPS stimulation. In this small cohort with 72 months follow-up period intracellular YB-1_acetyl levels, IL-6, uPAR, and IP10 correlated with excess mortality in the dialysis cohort. Changes in YB-1 acetylation and serum cytokines may, at a given time point, possibly predict the long-term outcome and thus provide a legacy effect in hemodialysis patients.

The nucleic acid binding protein YB-1-controlled expression of CXCL-1 modulates kidney damage in liver fibrosis

Acute kidney injury is a common complication of advanced liver disease and increased mortality of these patients. Here, we analyzed the role of Y-box protein-1 (YB-1), a nucleic acid binding protein, in the bile duct ligation model of liver fibrosis and monitored liver and subsequent kidney damage. Following bile duct ligation, both serum levels of liver enzymes and expression of hepatic extracellular matrix components such as type I collagen were significantly reduced in mice with half-maximal YB-1 expression (Yb1^+/-) as compared to their wild-type littermates. By contrast, expression of the chemokine CXCL1 was significantly augmented in these Yb1^+/- mice. YB-1 was identified as a potent transcriptional repressor of the Cxcl1 gene. Precision-cut kidney slices from Yb1^+/- mice revealed higher expression of the CXCL1 receptor CXCR2 as well as enhanced responsivity to CXCL1 compared to those from wild-type mice. Increased CXCL1 content in Yb1^+/- mice led to pronounced bile duct ligation-induced damage of the kidneys monitored as parameters of tubular epithelial injury and immune cell infiltration. Pharmacological blockade of CXCR2 as well as application of an inhibitory anti-CXCL1 antibody significantly mitigated early systemic effects on the kidneys following bile duct ligation whereas it had only a modest impact on hepatic inflammation and function. Thus, our analyses provide direct evidence that YB-1 crucially contributes to hepatic fibrosis and modulates liver-kidney crosstalk by maintaining tight control over chemokine CXCL1 expression.

Y-box binding protein 1 regulates ox-LDL mediated inflammatory responses and lipid uptake in macrophages

AIMS

Y-box protein 1 (YB1) is a key regulator of inflammatory mediators. However, the roles of YB1 in oxidized low-density lipoprotein (ox-LDL)-induced macrophage inflammation and lipid uptake remain less understood. Thus, we explored the roles of YB1 in ox-LDL-induced macrophage inflammation and lipid uptake and its underlying molecular mechanisms.

METHODS

An ox-LDL-induced atherosclerosis (AS) model was used in this study. Western blotting, RT-PCR, immunofluorescence, ELISA, dil-ox-LDL staining, a dual-luciferase reporter assay, RNA-binding protein immunoprecipitation (RIP) and in vivo experiments were used to detect each target.

RESULTS

ox-LDL downregulates YB1 expression in THP-1-derived macrophages and human monocyte-derived macrophages (hMDMs) via the NF-κB pathway. Downregulation of YB1 is facilitated by lipid uptake in macrophages, and CD36 is involved in this process. Furthermore, YB1 suppresses CD36 protein levels by directly binding to the coding sequence of the CD36 gene to promote CD36 mRNA decay but does not affect its mRNA transcription. Additionally, YB1 knockdown enhances the inflammatory response and lipid deposition via the NF-κB pathway in vivo.

CONCLUSION

ox-LDL decreases YB1 expression in macrophages, resulting in enhanced inflammatory responses by affecting NF-κB and facilitating lipid uptake by promoting scavenger receptor CD36 mRNA decay.

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.

Cold shock Y-box binding protein-1 acetylation status in monocytes is associated with systemic inflammation and vascular damage

BACKGROUND AND AIMS

In dialysis patients, vascular morbidities are highly prevalent and linked to leukocyte extravasation, especially of polarized monocytes. Experimental data demonstrate that phenotypic changes in monocytes require Y-box binding protein-1 (YB-1) upregulation.

METHODS

We determined YB-1 expression in circulating and vessel-invading monocytes from healthy controls and dialysis patients to correlate results with intima plaque formation and systemic inflammation.

RESULTS

Compared to healthy subjects, dialysis patients have fewer classical and more intermediate and non-classical monocytes. Post-translationally modified YB-1 (lysine 301/304 acetylation) is detected at high levels in the nucleus of adherent and invading CD14⁺CD68⁺ monocytes from umbilical cord and atherosclerosis-prone vessels. The content of non-acetylated YB-1 is significantly decreased (p < 0.001), whereas acetylated YB-1 is correspondingly increased (p < 0.001) throughout all monocyte subpopulations, such that the overall content remains unchanged.

CONCLUSIONS

In dialysis patients the YB-1 acetylation status is higher with prevailing diabetes and intima plaque formation. Pro-inflammatory mediators TNFα, IL-6, uPAR, CCL2, M-CSF, progranulin, ANP, and midkine, as well as anti-inflammatory IL-10 are significantly increased in dialysis patients, emphasizing a systemic inflammatory milieu. Strong positive correlations of monocytic YB-1 content are seen with ANP, IP-10, IL-6, and IL-10 serum levels. This is the first study demonstrating an association of cold shock protein YB-1 expression with inflammation in hemodialysis patients.

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.

YB-1 orchestrates onset and resolution of renal inflammation via IL10 gene regulation

The Y‐box‐binding protein (YB)‐1 plays a non‐redundant role in both systemic and local inflammatory response. We analysed YB‐1‐mediated expression of the immune regulatory cytokine IL‐10 in both LPS and sterile inflammation induced by unilateral renal ischaemia–reperfusion (I/R) and found an important role of YB‐1 not only in the onset but also in the resolution of inflammation in kidneys. Within a decisive cis‐regulatory region of the IL10 gene locus, the fourth intron, we identified and characterized an operative YB‐1 binding site via gel shift experiments and reporter assays in immune and different renal cells. In vivo, YB‐1 phosphorylated at serine 102 localized to the fourth intron, which was paralleled by enhanced IL‐10 mRNA expression in mice following LPS challenge and in I/R. Mice with half‐maximal expression of YB‐1 (Yb1^+/−) had diminished IL‐10 expression upon LPS challenge. In I/R, Yb1^+/− mice exhibited ameliorated kidney injury/inflammation in the early‐phase (days 1 and 5), however showed aggravated long‐term damage (day 21) with increased expression of IL‐10 and other known mediators of renal injury and inflammation.

In conclusion, these data support the notion that there are context‐specific decisions concerning YB‐1 function and that a fine‐tuning of YB‐1, for example, via a post‐translational modification regulates its activity and/or localization that is crucial for systemic processes such as inflammation.

Inflammatory cell infiltration and resolution of kidney inflammation is orchestrated by the cold-shock protein Y-box binding protein-1

Tubular cells recruit monocytic cells in inflammatory tubulointerstitial kidney diseases. The cell-cell communication that establishes pro- or anti-inflammatory activities is mainly influenced by cytokines, reactive oxygen species, nitric oxide, and phagocytosis. Key proteins orchestrating these processes such as cold-shock proteins linked with chemoattraction and cell maturation have been identified. The prototypic member of the cold-shock protein family, Y-box binding protein (YB)-1, governs specific phenotypic alterations in monocytic cells and was explored in the present study. Following tubulointerstitial injury by unilateral ureteral obstruction, increased inflammatory cell infiltration and tubular cell CCL5 expression was found in conditional Ybx1 knockout animals with specific depletion in monocytes/macrophages (YB-1^ΔLysM). Furthermore, YB-1^ΔLysM mice exhibit enhanced tissue damage, myofibroblast activation, and fibrosis. To investigate relevant molecular mechanism(s), we utilized bone marrow-derived macrophage cultures and found that YB-1-deficient macrophages display defects in cell polarization and function, including reduced proliferation and nitric oxide production, loss of phagocytic activity, and failure to upregulate IL-10 and CCL5 expression in response to inflammatory stimuli. Co-culture with primary tubular cells confirmed these findings. Thus, monocytic YB-1 has prominent and distinct roles for cellular feed-forward crosstalk and resolution of inflammatory processes by its ability to regulate cell differentiation and cytokine/chemokine synthesis.

RSK-mediated nuclear accumulation of the cold-shock Y-box protein-1 controls proliferation of T cells and T-ALL blasts

Deregulated proliferation is key to tumor progression. Although unrestricted proliferation of solid tumor cells correlates with the cold-shock protein Y-box (YB)-binding protein-1 accumulation in the nuclei, little is known about its expression and function in hematopoietic malignancies, such as T-cell acute lymphoblastic leukemia (T-ALL). Here we show that YB-1 protein is highly enriched in the nuclei of activated T cells and malignant human T-ALL cell lines but not in resting T cells. YB-1 S¹⁰² mutations that either mimic (S102D) or prevent phosphorylation (S102N) led to accumulation of YB-1 in the nucleus of T cells or strictly excluded it, respectively. Inactivation of ribosomal S6 kinase (RSK) was sufficient to abrogate T-cell and T-ALL cell proliferation, suggesting that RSK mediates cell-cycle progression, possibly dependent on YB-1-phosphorylation. Indeed, phosphomimetic YB-1^S102D enhanced proliferation implying that S¹⁰² phosphorylation is a prerequisite for malignant T-cell proliferation. At initial diagnosis of T-ALL, YB-1 localization was significantly altered in the nuclei of tumor blasts derived from bone marrow or peripheral blood. Our data show deregulated YB-1 in the nucleus as a yet unreported characteristic of T-ALL blasts and may refine strategies to restrict progression of hematopoietic tumors.

Therapeutic nuclear shuttling of YB-1 reduces renal damage and fibrosis

Virtually all chronic kidney diseases progress towards tubulointerstitial fibrosis. In vitro, Y-box protein-1 (YB-1) acts as a central regulator of gene transcription and translation of several fibrosis-related genes. However, it remains to be determined whether its pro- or antifibrotic propensities prevail in disease. Therefore, we investigated the outcome of mice with half-maximal YB-1 expression in a model of renal fibrosis induced by unilateral ureteral obstruction. Yb1^+/- animals displayed markedly reduced tubular injury, immune cell infiltration and renal fibrosis following ureteral obstruction. The increase in renal YB-1 was limited to a YB-1 variant nonphosphorylated at serine 102 but phosphorylated at tyrosine 99. During ureteral obstruction, YB-1 localized to the cytoplasm, directly stabilizing Col1a1 mRNA, thus promoting fibrosis. Conversely, the therapeutic forced nuclear compartmentalization of phosphorylated YB-1 by the small molecule HSc025 mediated repression of the Col1a1 promoter and attenuated fibrosis following ureteral obstruction. Blunting of these effects in Yb1^+/- mice confirmed involvement of YB-1. HSc025 even reduced tubulointerstitial damage when applied at later time points during maximum renal damage. Thus, phosphorylation and subcellular localization of YB-1 determines its effect on renal fibrosis in vivo. Hence, induced nuclear YB-1 shuttling may be a novel antifibrotic treatment strategy in renal diseases with the potential of damage reversal.

Transcriptional characteristics of different sized follicles in relation to embryo transferability: potential role of hepatocyte growth factor signalling

STUDY HYPOTHESIS

We hypothesized that a better discrimination between follicles containing oocytes with high developmental competence and those containing oocytes with low competence, based on a combination of a follicle's size and transcriptomic signature, will provide a reliable method to predict embryonic outcome of IVF.

STUDY FINDING

This study provides new insights on the impact of follicular size on oocyte quality as measured by embryonic development and demonstrates that medium follicles yield a better percentage of transferable embryos.

WHAT IS KNOWN ALREADY

Although it is generally accepted that large ovarian follicles contain better eggs, other studies report that a better follicular size subdivision and a better characterization are needed.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

Individual follicles (n = 136), from a total of 33 women undergoing IVF, were aspirated and categorized on the basis of their follicular liquid volume (small, medium or large) and the embryonic outcome of the enclosed oocyte: poor or good development. Comprehensive gene expression analysis between cells from the different sized follicles was performed using microarrays and quantitative RT-PCR to find molecular markers associated with follicular maturity and oocyte developmental competence.

MAIN RESULTS AND THE ROLE OF CHANCE

The analysis of embryonic outcome in relation to follicular size indicates that the medium-sized follicles category yielded more transferable embryos (35%) compared with the largest follicles (30%) (NS). Gene expression analysis revealed expression markers with significant (P < 0.05) discrimination between the poor development groups for all three follicle sizes, and good development medium-size follicles, including up-regulation of thrombomodulin, transforming growth factor, beta receptor II and chondrolecti, and those associated with hyaluronan synthesis, coagulation and hepatocyte growth factor signalling.

LIMITATIONS, REASONS FOR CAUTION

These analyses were performed in a single cohort of patients coming from a single clinic and the biomarkers generated will require validation in different geographical and biological contexts to ensure their global applicability.

WIDER IMPLICATIONS OF THE FINDINGS

Medium-size follicles seem to be the optimal size for a positive embryonic outcome and are associated with competence markers that may help in understanding the ideal differentiation status during late folliculogenesis.

LARGE SCALE DATA

The data discussed in this publication have been deposited in The National Center for Biotechnology Information Gene Expression Omnibus database and are accessible through GEO Series accession number GSE52851.

STUDY FUNDING AND COMPETING INTERESTS

This study was supported by Canadian Institutes of Health Research (CIHR) and Natural Sciences and Engineering Research Council of Canada (NSERC) to M.A.S. There are no competing interests to declare.

Overexpression of YB1 C-terminal domain inhibits proliferation, angiogenesis and tumorigenicity in a SK-BR-3 breast cancer xenograft mouse model

Y-box-binding protein 1 (YB1) is a multifunctional transcription factor with vital roles in proliferation, differentiation and apoptosis. In this study, we have examined the role of its C-terminal domain (YB1 CTD) in proliferation, angiogenesis and tumorigenicity in breast cancer. Breast cancer cell line SK-BR-3 was infected with GFP-tagged YB1 CTD adenovirus expression vector. An 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) proliferation assay showed that YB1 CTD decreased SK-BR-3 cell proliferation, and down-regulated cyclin B1 and up-regulated p21 levels in SK-BR-3 cells. YB1 CTD overexpression changed the cytoskeletal organization and slightly inhibited the migration of SK-BR-3 cells. YB1 CTD also inhibited secreted VEGF expression in SK-BR-3 cells, which decreased SK-BR-3-induced EA.hy926 endothelial cell angiogenesis in vitro. YB1 CTD overexpression attenuated the ability of SK-BR-3 cells to form tumours in nude mice, and decreased in vivo VEGF levels and angiogenesis in the xenografts in SK-BR-3 tumour-bearing mice. Taken together, our findings demonstrate the vital role of YB1 CTD overexpression in inhibiting proliferation, angiogenesis and tumorigenicity of breast cancer cell line SK-BR-3.

The Role of the Y Box Binding Protein 1 C-Terminal Domain in Vascular Endothelial Cell Proliferation, Apoptosis, and Angiogenesis

Different domains of the multifunctional transcription factor Y-box binding protein 1 (YB1) regulate proliferation, differentiation, and apoptosis by transactivating or repressing the promoters of various genes. Here we report that the C-terminal domain of YB1 (YB1 CTD) is involved in endothelial cell proliferation, apoptosis, and tube formation. The oligo pull-down assays demonstrated that YB1 directly binds double-stranded GC box sequences in endothelial cells through the 125-220 amino acids. Adenovirus expression vectors harboring green fluorescent protein (GFP) or GFP-tagged YB1 CTD were constructed and used to infect EA.hy926 endothelial cells. Overexpression of the YB1 CTD significantly increased p21 expression, decreased cyclin B1 expression, and inhibited the proliferation of EA.hy926 cells. YB1 CTD overexpression also increased Bax and active caspase 3 expression, decreased Bcl-2 expression, and induced apoptosis in EA.hy926 cells. Furthermore, overexpression of the YB1 CTD significantly suppressed migration and tube formation in EA.hy926 cells. Finally, YB1 CTD decreased ERK1/2 phosphorylation in EA.hy926 cells. These findings demonstrated vital roles for YB1 in endothelial cell proliferation, apoptosis, and tube formation through transcriptional regulation of GC box-related genes.

Differential control of interleukin-6 mRNA levels by cellular distribution of YB-1

Cytokine production is essential for innate and adaptive immunity against microbial invaders and must be tightly controlled. Cytokine messenger RNA (mRNA) is in constant flux between the nucleus and the cytoplasm and in transcription, splicing, or decay; such processes must be tightly controlled. Here, we report a novel function of Y-box-binding protein 1 (YB-1) in modulating interleukin-6 (IL-6) mRNA levels in a cell type-specific manner. In lipopolysaccharide (LPS)-stimulated macrophages, YB-1 interacts with IL-6 mRNA and actively transports it to the extracellular space by YB-1-enriched vesicles, resulting in the proper maintenance of intracellular IL-6 mRNA levels. YB-1 secretion occurs in a cell type-specific manner. Whereas macrophages actively secret YB-1, dendritic cells maintain it predominantly in the cytoplasm even in response to LPS. Intracellular YB-1 has the distinct function of regulating IL-6 mRNA stability in dendritic cells. Moreover, because LPS differentially regulates the expression of histone deacetylase 6 (HDAC6) in macrophages and dendritic cells, this stimulus might control YB-1 acetylation differentially in both cell types. Taken together, these results suggest a unique feature of YB-1 in controlling intracellular IL-6 mRNA levels in a cell type-specific manner, thereby leading to functions that are dependent on the extracellular and intracellular distribution of YB-1.

Calcineurin-mediated YB-1 dephosphorylation regulates CCL5 expression during monocyte differentiation

Y-box (YB) protein-1 serves as a master regulator in gene transcription and mRNA translation. YB-1 itself is regulated at various levels, e.g. through post-translational modifications. In our previous work, we identified RANTES/CCL5 as a transcriptional target of YB-1. We previously demonstrated that YB-1 protein is transiently up-regulated during monocyte/macrophage differentiation evidenced in monocytic cells (THP-1 cells) that were differentiated using phorbol myristate acetate (PMA). Here we provide evidence that YB-1 phosphorylation, specifically at its serine residue 102 (Ser-102), increases early on in THP-1 cells following PMA treatment as well as in differentiated primary human monocytes. This process is mediated through the Akt signaling pathway. Ser-102-phosphorylated YB-1 displays stronger binding affinity and trans-activating capacity at the CCL5 gene promoter. Notably, Ser-102-phosphorylated YB-1 disappears at later stages of the monocyte/macrophage differentiation process. We demonstrate that serine-threonine phosphatase calcineurin (CN) dephosphorylates YB-1 preventing it from binding to and trans-activating the CCL5 promoter. Co-immunoprecipitation assays prove a direct YB-1/CN interaction. Furthermore, analyses in kidney tissues from mice that were treated with the CN inhibitor cyclosporine A revealed an in vivo effect of CN on the YB-1 phosphorylation status. We conclude that YB-1 phosphorylation at Ser-102 is an important prerequisite for CCL5 promoter activation during macrophage differentiation. Our findings point to a critical role of YB-1 in the resolution of inflammatory processes which may largely be due to CN-mediated dephosphorylation.

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.

Effector mechanisms of rejection

Organ transplantation appears today to be the best alternative to replace the loss of vital organs induced by various diseases. Transplants can, however, also be rejected by the recipient. In this review, we provide an overview of the mechanisms and the cells/molecules involved in acute and chronic rejections. T cells and B cells mainly control the antigen-specific rejection and act either as effector, regulatory, or memory cells. On the other hand, nonspecific cells such as endothelial cells, NK cells, macrophages, or polymorphonuclear cells are also crucial actors of transplant rejection. Last, beyond cells, the high contribution of antibodies, chemokines, and complement molecules in graft rejection is discussed in this article. The understanding of the different components involved in graft rejection is essential as some of them are used in the clinic as biomarkers to detect and quantify the level of rejection.

Cold shock Y-box protein-1 proteolysis autoregulates its transcriptional activities

BACKGROUND

The Y-box protein-1 (YB-1) fulfills pleiotropic functions relating to gene transcription, mRNA processing, and translation. It remains elusive how YB-1 shuttling into the nuclear and cytoplasmic compartments is regulated and whether limited proteolysis by the 20S proteasome releases fragments with distinct function(s) and subcellular distribution(s).

RESULTS

To address these questions, mapping of domains responsible for subcellular targeting was performed. Three nuclear localization signals (NLS) were identified. NLS-1 (aa 149-156) and NLS-2 (aa 185-194) correspond to residues with unknown function(s), whereas NLS-3 (aa 276-292) matches with a designated multimerization domain. Nuclear export signal(s) were not identified. Endoproteolytic processing by the 20S proteasome before glycine 220 releases a carboxy-terminal fragment (CTF), which localized to the nucleus, indicating that NLS-3 is operative. Genotoxic stress induced proteolytic cleavage and nuclear translocation of the CTF. Co-expression of the CTF and full-length YB-1 resulted in an abrogated transcriptional activation of the MMP-2 promoter, indicating an autoregulatory inhibitory loop, whereas it fulfilled similar trans-repressive effects on the collagen type I promoter.

CONCLUSION

Compartmentalization of YB-1 protein derivatives is controlled by distinct NLS, one of which targets a proteolytic cleavage product to the nucleus. We propose a model for an autoregulatory negative feedback loop that halts unlimited transcriptional activation.

YB-1 is an early and central mediator of bacterial and sterile inflammation in vivo

In vitro studies identified Y-box-binding protein (YB)-1 as a key regulator of inflammatory mediators. In this study, we observed increased levels of secreted YB-1 in sera from sepsis patients. This led us to investigate the in vivo role of YB-1 in murine models of acute peritonitis following LPS injection, in sterile renal inflammation following unilateral ureteral obstruction, and in experimental pyelonephritis. LPS injection enhanced de novo secretion of YB-1 into the urine and the peritoneal fluid of LPS-treated mice. Furthermore, we could demonstrate a significant, transient upregulation and posttranslational modification (phosphorylation at serine 102) of YB-1 in renal and inflammatory cells. Increased renal cytoplasmic YB-1 amounts conferred enhanced expression of proinflammatory chemokines CCL2 and CCL5. Along these lines, heterozygous YB-1 knockout mice (YB-1(+/d)) that display 50% reduced YB-1 levels developed significantly lower responses to both LPS and sterile inflammation induced by unilateral ureteral obstruction. This included diminished immune cell numbers due to impaired migration propensities and reduced chemokine expression. YB-1(+/d) mice were protected from LPS-associated mortality (20% mortality on day 3 versus 80% in wild-type controls); however, immunosuppression in YB-1(+/d) animals resulted in 50% mortality. In conclusion, our findings identify YB-1 as a major, nonredundant mediator in both systemic and local inflammatory responses.

Cloning, characterization and expression analysis of a cold shock domain family member YB-1 in turbot Scophthalmus maximus

The Y-box proteins are a family of highly conserved nucleic acid binding proteins. In this report we have identified a new member, YB-1 from turbot (Scophthalmus maximus) spleen cDNA library. The full-length cDNA sequence of turbot YB-1 was obtained and then the expression at transcriptional level was researched by qRT-PCR. In normal organs, the expression of YB-1 was higher in liver, brain, gill and heart, respectively. YB-1 had the highest expression level at gastrula stage during the early stages of embryo development. In the liver, kidney and spleen, the turbot YB-1 expression level was the highest at 72 h after challenge with lymphocystis disease virus (LCDV) and the highest at 12 h after challenge with Vibrio anguillarum (V. anguillarum). Furthermore, the expression of turbot YB-1 also distinctly increased in turbot kidney cells (TK) at 24 h after challenge with V. anguillarum and LCDV. These results indicated that the turbot YB-1 protein may play a significant role in the immune response of turbot.

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.

Cold-shock domain family member YB-1 expression in endometrium and endometriosis

BACKGROUND

The Y-box-binding protein (YB-1) is described as a potential oncogene highly expressed in tumors and associated with increased cell survival, proliferation, migration and anti-apoptotic signaling. The aim of our study was to examine the expression and role of YB-1 in human endometriosis (Eo) and its association with cell survival, proliferation and invasion.

METHODS

We analyzed the gene and protein expression levels of YB-1 by quantitative real-time RT-PCR and immunoassays, respectively, in peritoneal macrophages, ovarian endometrioma and eutopic endometrial tissues/cells derived from women with (n= 120) and without (n= 91) Eo. We also evaluated the functional consequences of YB-1 knockdown in the Z12 Eo cell line by measuring cell proliferation [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid cell proliferation assay], invasion (Matrigel invasion assay) and spontaneous and tumour necrosis factor (TNFα)-induced RANTES (regulated upon activation, normal T-cell expressed and secreted chemokine) expression and apoptosis (ELISA-based assay).

RESULTS

YB-1 gene and protein expression was statistically significantly higher in ovarian lesions, eutopic endometrium and peritoneal macrophages of patients with Eo in comparison with the control group. Interestingly, the strongest YB-1 expression was observed in the epithelial compartment of endometrial tissues. In the Z12 cell line, YB-1 knockdown resulted in significant cell growth inhibitory effects including reduced cell proliferation and increased rates of spontaneous and TNFα-induced apoptosis. Significantly, higher RANTES expression and decreased cell invasion in vitro were also associated with YB-1 inactivation.

CONCLUSION

High YB-1 expression could have an impact on the development and progression of Eo. This study suggests the role of YB-1 as a potential therapeutic target for Eo patients.

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.

Increased expression of peripheral blood leukocyte genes implicate CD14+ tissue macrophages in cellular intestine allograft rejection

Recurrent rejection shortens graft survival after intestinal transplantation (ITx) in children, most of whom also experience early acute cellular rejection (rejectors). To elucidate mechanisms common to early and recurrent rejection, we used a test cohort of 20 recipients to test the hypothesis that candidate peripheral blood leukocyte genes that trigger rejection episodes would be evident late after ITx during quiescent periods in genome-wide gene expression analysis and would achieve quantitative real-time PCR replication pre-ITx (another quiescent period) and in the early post-ITx period during first rejection episodes. Eight genes were significantly up-regulated among rejectors in the late post-ITx and pre-ITx periods, compared with nonrejectors: TBX21, CCL5, GNLY, SLAMF7, TGFBR3, NKG7, SYNE1, and GK5. Only CCL5 was also up-regulated in the early post-ITx period. Among resting peripheral blood leukocyte subsets in randomly sampled nonrejectors, CD14(+) monocytes expressed the CCL5 protein maximally. Compared with nonrejectors, rejectors demonstrated higher counts of both circulating CCL5(+)CD14(+) monocytes and intragraft CD14(+) monocyte-derived macrophages in immunohistochemistry of postperfusion and early post-ITx biopsies from the test and an independent replication cohort. Donor-specific alloreactivity measured with CD154(+) T-cytotoxic memory cells correlated with the CCL5 gene and intragraft CD14(+) monocyte-derived macrophages at graft reperfusion and early post-ITx. CCL5 gene up-regulation and CD14(+) macrophages likely prime cellular ITx rejection. Infiltration of reperfused intestine allografts with CD14(+) macrophages may predict rejection events.

Y-box protein-1 is a transcriptional regulator of BMP7

Bone morphogenetic protein-7 (BMP7) is an endogenous antifibrogenic protein in the kidney which is down regulated in experimental chronic kidney diseases such as obstructive and diabetic nephropathy in parallel with progressively increasing TGFβ. In vitro studies were performed in Madin-Darby Canine Kidney (MDCK)-cells to identify transcriptional regulators of BMP7. Experiments with various BMP7 promoter fragments (465-4,267  bp) identify small proximal promoter segments that are transcriptionally activated by high glucose (3.2-fold) but down regulated by TGFβ (0.2-fold) compared to normal glucose. Protein binding to these DNA segments is increased by high glucose and decreased by TGFβ in a time-dependent, progressive manner. Analysis of BMP7 promoter-binding proteins with liquid chromatography/tandem mass spectrometry (LC/MS/MS) identifies seven unique, partially overlapping peptides, spanning 25% of the amino acid sequence of Y-box protein-1 (YB1). EMSA-Western blot combination experiments confirm that YB1 is a BMP7 promoter-binding protein. YB1 knock-down reduces transcriptional responses to high glucose and TGFβ by about one-half, respectively. In addition, high glucose induces but TGFβ reduces nuclear translocation of YB1 from the cytoplasm. These studies identify YB1 as a transcriptional activator of BMP7 and helps to explain the progressive decline in renal BMP7 in diabetic nephropathy and other kidney diseases.

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.

Y-box protein-1/p18 fragment identifies malignancies in patients with chronic liver disease

Background

Immunohistochemical detection of cold shock proteins is predictive for deleterious outcome in various malignant diseases. We recently described active secretion of a family member, denoted Y-box (YB) protein-1. We tested the clinical and diagnostic value of YB-1 protein fragment p18 (YB-1/p18) detection in blood for malignant diseases.

Methods

We used a novel monoclonal anti-YB-1 antibody to detect YB-1/p18 by immunoblotting in plasma samples of healthy volunteers (n = 33), patients with non-cancerous, mostly inflammatory diseases (n = 60), hepatocellular carcinoma (HCC; n = 25) and advanced solid tumors (n = 20). YB-1/p18 was then tested in 111 patients with chronic liver diseases, alongside established tumor markers and various diagnostic measures, during evaluation for potential liver transplantation.

Results

We developed a novel immunoblot to detect the 18 kD fragment of secreted YB-1 in human plasma (YB-1/p18) that contains the cold-shock domains (CSD) 1-3 of the full-length protein. YB-1/p18 was detected in 11/25 HCC and 16/20 advanced carcinomas compared to 0/33 healthy volunteers and 10/60 patients with non-cancerous diseases. In 111 patients with chronic liver disease, YB-1/p18 was detected in 20 samples. Its occurrence was not associated with advanced Child stages of liver cirrhosis or liver function. In this cohort, YB-1/p18 was not a good marker for HCC, but proved most powerful in detecting malignancies other than HCC (60% positive) with a lower rate of false-positive results compared to established tumor markers. Alpha-fetoprotein (AFP) was most sensitive in detecting HCC, but simultaneous assessment of AFP, CA19-9 and YB-1/p18 improved overall identification of HCC patients.

Conclusions

Plasma YB-1/p18 can identify patients with malignancies, independent of acute inflammation, renal impairment or liver dysfunction. The detection of YB-1/p18 in human plasma may have potential as a tumor marker for screening of high-risk populations, e.g. before organ transplantation, and should therefore be evaluated in larger prospective studies.

Vitamin D and cardiovascular risk

Vitamin D deficiency results in abnormal mineralization of bones and has resulted in prevention programs for children with supplementation when they are breast fed. Further activities of vitamin D relate to defence of microbial infections, e.g. tuberculosis, prevention of cancer, contractility of muscle cells and counteraction of congestive heart failure. Given early reports in the 1960s on deleterious effects of vitamin D supplementation in rodents, that is ectopic media ossification of arterial vessels, a pro-atherogenic function had been anticipated for humans as well. However, cross-sectional studies reveal that vitamin D deficiency in humans is associated with elevated blood pressure and propagation of atherogenesis. These contradictory findings on the progression of atherosclerosis may be reconciled by dissecting the activation mechanism(s) of vitamin D in rodents versus humans. Notably, novel findings convincingly indicate that vitamin D exerts anti-inflammatory effects. In conclusion, vitamin D supplementation in adults may be regarded as simple means with few potential side effects to prevent atherogenesis or halt its progression and combat arterial hypertension. Adjustment of vitamin D dosing regimens is required in patients with chronic kidney disease; however, prospective clinical trials are urgently needed to guide these recommendations with evidence.

YB-1 acts as a ligand for Notch-3 receptors and modulates receptor activation

Y-box (YB) protein-1 is secreted by mesangial and immune cells after cytokine challenge, but extracellular functions are unknown. Here, we demonstrate that extracellular YB-1 associates with outer cell membrane components and interacts with extracellular Notch-3 receptor domains. The interaction appears to be specific for Notch-3, as YB-1-green fluorescent protein binds to the extracellular domains and full-length forms of Notch-3 but not to Notch-1. YB-1-green fluorescent protein and Notch-3 proteins co-localize at cell membranes, and extracellular YB-1 activates Notch-3 signaling, resulting in nuclear translocation of the Notch-3 intracellular domain and up-regulation of Notch target genes. The YB-1/Notch-3 interaction may be of particular relevance for inflammatory mesangioproliferative disease, as both proteins co-localize in an experimental nephritis model and receptor activation temporally and spatially correlates with YB-1 expression.