ZNF580 - a brake on Interleukin-6.

BACKGROUND: Zinc finger protein 580 (ZNF580) was reported to modulate angiogenesis, endothelial homeostasis and blood pressure control. ZNF580 regulated genes include VEGF-A and IL-8. However, it is unknown if ZNF580 could play a role during inflammation. The aim of this study was to find out if ZNF580 affects the expression of IL-6, if it occurs in monocytic cells and responds to inflammatory mediators. RESULTS: Overexpression of ZNF580 reduced LPS-induced promotor activity of IL-6. Consistently, overexpression of ZNF580 reduced by half the LPS-induced expression of IL-6. ZNF580 was strongly expressed in the nucleus of MonoMac6, a human monocytic cell line. LPS-stimulated IL-6 secretion increased when ZNF580 was suppressed with siRNA. After stimulation of MonoMac6 with LPS for 24 h, ZNF580 negatively correlated with the amount of secreted IL-6. In response to LPS, ZNF580 was increased within the first 8 h, followed by a marked decrease after 16 h. This decrease coincided with sustained IL-6 production. CONCLUSION: This study demonstrated that ZNF580 inhibits LPS-induced expression of IL-6. ZNF580 was highly expressed in monocytic cells and therefore may contribute to the modulation of its IL-6 production, at least in response to LPS. This suggests cooperation between ZNF580 and NFκB, which could play a role during sepsis.

The impact of α-Lipoic acid on cell viability and expression of nephrin and ZNF580 in normal human podocytes.

Human podocytes (hPC) are essential for maintaining normal kidney function and dysfunction or loss of hPC play a pivotal role in the manifestation and progression of chronic kidney diseases including diabetic nephropathy. Previously, α-Lipoic acid (α-LA), a licensed drug for treatment of diabetic neuropathy, was shown to exhibit protective effects on diabetic nephropathy in vivo. However, the effect of α-LA on hPC under non-diabetic conditions is unknown. Therefore, we analyzed the impact of α-LA on cell viability and expression of nephrin and zinc finger protein 580 (ZNF580) in normal hPC in vitro. Protein analyses were done via Western blot techniques. Cell viability was determined using a functional assay. hPC viability was dynamically modulated via α-LA stimulation in a concentration-dependent manner. This was associated with reduced nephrin and ZNF580 expression and increased nephrin phosphorylation in normal hPC. Moreover, α-LA reduced nephrin and ZNF580 protein expression via 'kappa-light-chain-enhancer' of activated B-cells (NF-κB) inhibition. These data demonstrate that low α-LA had no negative influence on hPC viability, whereas, high α-LA concentrations induced cytotoxic effects on normal hPC and reduced nephrin and ZNF580 expression via NF-κB inhibition. These data provide first novel information about potential cytotoxic effects of α-LA on hPC under non-diabetic conditions.

Update on the Protective Renal Effects of Metformin in Diabetic Nephropathy.

BACKGROUND: Diabetic nephropathy is one of the most important complications in patients with diabetes mellitus. Main steps crucial for the pathogenesis of diabetic nephropathy involve amongst others the modulation of cell signaling via AMP-activated kinase (AMPK) and mammalian target of rapamycin (mTOR), reactive oxygen generation, and endoplasmic reticulum stress under diabetic or hyperglycemic conditions. These processes mediate increased loss of renal cells, such as podocytes, which consequentially leads to renal damage and loss of renal functions, such as structural integrity and glomerular filtration in diabetic nephropathy. The anti-diabetic drug metformin has been widely used for pharmacotherapeutic treatment of patients with diabetes mellitus. Besides its anti-diabetic actions, recent studies revealed additional nephroprotective effects of metformin in vitro and in vivo. Metformin was found to diminish apoptosis in different experimental renal settings. Moreover, it was shown to reduce albuminuria in diabetic rats as well as in patients with type 2 diabetes mellitus. These effects were demonstrated to be mediated via the AMPK/mTOR signaling axis. These data indicate beneficial and renoprotective effects of metformin in diabetic nephropathy. OBJECTIVE: In this review, we will summarize the latest findings regarding the nephroprotective impact of metformin in vitro and in vivo. Moreover, we will depict and discuss the therapeutic potential of this drug for the treatment of diabetic nephropathy.

Tissue Factor: A Conventional or Alternative Target in Cancer Therapy.

BACKGROUND: Tissue factor (TF) is an evolutionary conserved glycoprotein that plays an important role in the pathogenesis of cancer. TF is expressed in 2 naturally occurring protein isoforms, membrane-bound full-length (fl)TF and soluble alternatively spliced (as)TF. Both isoforms have been shown to affect a variety of pathophysiologically relevant functions, such as tumor-associated angiogenesis, thrombogenicity, tumor growth, and metastasis. Therefore, targeting TF either by direct inhibition or indirectly, i.e., on a posttranscriptional level, offers a novel therapeutic option for cancer treatment. CONTENT: In this review we summarize the latest findings regarding the role of TF and its isoforms in cancer biology. Moreover, we briefly depict and discuss the therapeutic potential of direct and/or indirect inhibition of TF activity and expression for the treatment of cancer. SUMMARY: asTF and flTF play important and often distinct roles in cancer biology, i.e., in thrombogenicity and angiogenesis, which is mediated by isoform-specific signal transduction pathways. Therefore, both TF isoforms and downstream signaling are promising novel therapeutic targets in malignant diseases.

The role of tissue factor isoforms in cancer biology.

Tissue Factor (TF) is an evolutionary conserved glycoprotein, which is of immense importance for a variety of biologic processes. TF is expressed in two naturally occurring protein isoforms, membrane-bound "full-length" (fl)TF and soluble alternatively spliced (as)TF. The TF isoform expression is differentially modulated on post-transcriptional level via regulatory factors, such as serine/arginine-rich (SR) proteins, SR protein kinases and micro (mi)RNAs. Both isoforms mediate a variety of physiologic- and pathophysiologic-relevant functions, such as thrombogenicity, angiogenesis, cell signaling, tumor cell proliferation and metastasis. In this review, we will depict the main mechanisms regulating the TF isoform expression in cancer and under other pathophysiologic-relevant conditions. Moreover, we will summarize and discuss the latest findings regarding the role of TF and its isoforms in cancer biology.

The impact of microRNAs on the regulation of tissue factor biology.

Tissue factor (TF) and its isoforms play an important role in a variety of physiologic and pathophysiologic functions, such as initiation of blood coagulation, vessel wall hemostasis, angiogenesis, and tumorigenesis. Micro(mi)RNAs are crucial for post-transcriptional control of protein generation by regulating the expression of one-third of all human genes. In recent years, miRNAs were shown to modulate the expression and biologic function of TF in different physiologic- and pathophysiologic-relevant settings, such as in autoimmune diseases and in different types of cancer. In the present review, we will summarize and discuss the latest findings regarding the impact of miRNAs on the generation of TF and its isoforms as well as on regulation of TF biology under normal and pathophysiologic conditions.

Post-transcriptional fine-tuning of COP9 signalosome subunit biosynthesis is regulated by the c-Myc/Lin28B/let-7 pathway.

The COP9 signalosome (CSN) complex controls protein degradation via the ubiquitin (Ub) proteasome system (UPS) in eukaryotes. In mammalian cells, the multimeric CSN is composed of eight subunits (CSN1 - CSN8). It regulates cullin-RING Ub ligases (CRLs), which target essential regulatory proteins for ubiquitination and subsequent degradation. Thereby, the CSN cooperates with the UPS in a variety of essential cellular functions, including DNA repair, cell cycle and differentiation. Although functions of the CSN have been elucidated, mechanisms and regulatory principles of its de novo formation are completely unknown. Here, we show that there is a fundamental mechanism that allows a coordinated expression of all CSN subunits, a prerequisite for CSN assembly. CSN subunit mRNAs are targets of miRNAs of the let-7 family suppressing CSN subunit expression in human cells. Factors that reduce or block let-7 miRNAs induce the coordinated expression of CSN subunits. For instance, over-expression of CSN1 specifically traps let-7a-1 miRNA and elevates CSN subunit levels by two- to fourfold in a coordinated manner. CSN subunit expression is also increased by specific miRNA inhibitors or by interferon (IFN)-mediated induction of STAT1 and c-Myc reducing levels of let-7 miRNAs. Activation of STAT1 by IFNα or IFNγ induces c-Myc, which increases CSN subunit expression via the Lin28B/let-7 regulatory pathway. By contrast, a let-7a-1 mimic reduces CSN subunit expression. Our data show that let-7 miRNAs control the fine-tuning and coordinated expression of subunits for CSN de novo formation, presumably a general regulatory principle for other Zomes complexes as well.