Endoplasmic reticulum stress enhances fibrosis through IRE1α-mediated degradation of miR-150 and XBP-1 splicing

ER stress results in activation of the unfolded protein response and has been implicated in the development of fibrotic diseases. In this study, we show that inhibition of the ER stress-induced IRE1α signaling pathway, using the inhibitor 4μ8C, blocks TGFβ-induced activation of myofibroblasts in vitro, reduces liver and skin fibrosis in vivo, and reverts the fibrotic phenotype of activated myofibroblasts isolated from patients with systemic sclerosis. By using IRE1α(-/-) fibroblasts and expression of IRE1α-mutant proteins lacking endoribonuclease activity, we confirmed that IRE1α plays an important role during myofibroblast activation. IRE1α was shown to cleave miR-150 and thereby to release the suppressive effect that miR-150 exerted on αSMA expression through c-Myb. Inhibition of IRE1α was also demonstrated to block ER expansion through an XBP-1-dependent pathway. Taken together, our results suggest that ER stress could be an important and conserved mechanism in the pathogenesis of fibrosis and that components of the ER stress pathway may be therapeutically relevant for treating patients with fibrotic diseases

Inhibiting IRE1α-endonuclease activity decreases tumor burden in a mouse model for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a liver tumor that usually arises in patients with cirrhosis. Hepatic stellate cells are key players in the progression of HCC, as they create a fibrotic micro-environment and produce growth factors and cytokines that enhance tumor cell proliferation and migration. We assessed the role of endoplasmic reticulum (ER) stress in the cross-talk between stellate cells and HCC-cells. Mice with a fibrotic HCC were treated with the IRE1α-inhibitor 4μ8C, which reduced tumor burden and collagen deposition. By co-culturing HCC-cells with stellate cells, we found that HCC-cells activate IREα in stellate cells, thereby contributing to their activation. Inhibiting IRE1α blocked stellate cell activation, which then decreased proliferation and migration of tumor cells in different in vitro 2D and 3D co-cultures. In addition, we also observed cell-line specific direct effects of inhibiting IRE1α in tumor cells

Minor Abnormalities of Testis Development in Mice Lacking the Gene Encoding the MAPK Signalling Component, MAP3K1

In mammals, the Y chromosome is a dominant male determinant, causing the bipotential gonad to develop as a testis. Recently, cases of familial and spontaneous 46,XY disorders of sex development (DSD) have been attributed to mutations in the human gene encoding mitogen-activated protein kinase kinase kinase 1, MAP3K1, a component of the mitogen-activated protein kinase (MAPK) signal transduction pathway. In individuals harbouring heterozygous mutations in MAP3K1, dysregulation of MAPK signalling was observed in lymphoblastoid cell lines, suggesting a causal role for these mutations in disrupting XY sexual development. Mice lacking the cognate gene, Map3k1, are viable and exhibit the eyes open at birth (EOB) phenotype on a mixed genetic background, but on the C57BL/6J genetic background most mice die at around 14.5 dpc due to a failure of erythropoiesis in the fetal liver. However, no systematic examination of sexual development in Map3k1-deficient mice has been described, an omission that is especially relevant in the case of C57BL/6J, a genetic background that is sensitized to disruptions to testis determination. Here, we report that on a mixed genetic background mice lacking Map3k1 are fertile and exhibit no overt abnormalities of testis development. On C57BL/6J, significant non-viability is observed with very few animals surviving to adulthood. However, an examination of development in Map3k1-deficient XY embryos on this genetic background revealed no significant defects in testis determination, although minor abnormalities were observed, including an increase in gonadal length. Based on these observations, we conclude that MAP3K1 is not required for mouse testis determination. We discuss the significance of these data for the functional interpretation of sex-reversing MAP3K1 mutations in humans

Loss of Mitogen-Activated Protein Kinase Kinase Kinase 4 (MAP3K4) Reveals a Requirement for MAPK Signalling in Mouse Sex Determination

The boygirl (byg) mouse mutant reveals that MAP3K4-mediated signaling is necessary for normal SRY expression and testis specification in the developing mouse gonad

Identification of human renal cell carcinoma associated genes by suppression subtractive hybridization

Renal cell carcinoma (RCC) are frequently chemo- and radiation resistant. Thus, there is a need for identifying biological features of these cells that could serve as alternative therapeutic targets. We performed suppression subtractive hybridization (SSH) on patient-matched normal renal and RCC tissue to identify variably regulated genes. 11 genes were strongly up-regulated or selectively expressed in more than one RCC tissue or cell line. Screening of filters containing cancer-related cDNAs confirmed overexpression of 3 of these genes and 3 additional genes were identified. These 14 differentially expressed genes, only 6 of which have previously been associated with RCC, are related to tumour growth/survival (EGFR, cyclin D1, insulin-like growth factor-binding protein-1 and a MLRQ sub-unit homologue of the NADH:ubiquinone oxidoreductase complex), angiogenesis (vascular endothelial growth factor, endothelial PAS domain protein-1, ceruloplasmin, angiopoietin-related protein 2) and cell adhesion/motility (protocadherin 2, cadherin 6, autotaxin, vimentin, lysyl oxidase and semaphorin G). Since some of these genes were overexpressed in 80–90% of RCC tissues, it is important to evaluate their suitability as therapeutic targets. © 2001 Cancer Research Campaig

Engineered allosteric activation of kinases in living cells

Studies of cellular and tissue dynamics benefit greatly from tools that can control protein activity with specificity and precise timing in living systems. We describe here a new approach to confer allosteric regulation specifically on the catalytic activity of kinases. A highly conserved portion of the kinase catalytic domain is modified with a small protein insert that inactivates catalytic activity, but does not affect other protein interactions. Catalytic activity is restored by addition of rapamycin or non-immunosuppresive analogs (Fig. 1A). We demonstrate the approach by specifically activating focal adhesion kinase (FAK) within minutes in living cells, thereby demonstrating a novel role for FAK in regulation of membrane dynamics. Molecular modeling and mutagenesis indicate that the protein insert reduces activity by increasing the flexibility of the catalytic domain. Drug binding restores activity by increasing rigidity. Successful regulation of Src and p38 suggest that modification of this highly conserved site will be applicable to other kinases

A2a/D2 receptor interactions are not observed in COS-7 cells transiently transfected with dopamine D2 and adenosine A2a receptor cDNA.

The rat D2 receptor and the dog A2a receptor subcloned into the pXM vector were transiently transfected into COS-7 cells using the DEAE-dextran method. The transfected cells expressed approx. 200 fmol D2 receptors/mg protein and approx. 5 pmol/mg protein of the A2a receptor as judged by binding experiments with [3H]raclopride [or[3H]-N-propyl-apomorphine (NPA)] and [3H]-CGS 21680, respectively. The high affinity KD values were 0.43 and 19 nM for D2 and A2a receptors, respectively, in agreement with results obtained from other cells and tissues. The non-selective adenosine receptor agonist NECA stimulated cAMP accumulation both in non-transfected and transfected COS-7 cells with only a slight difference in potency, suggesting that most of the stimulation is due to activation of A2b receptors known to be present on virtually every cell. The two A2a selective agonists CGS 21680 and CV-1808 were essentially inactive in transfected COS-7 cells, but were very active in PC-12 cells known to possess functional A2a receptors. Dopamine did not decrease cAMP accumulation in the transfected COS-7 cells. CGS 21680 (30 nM) did not affect the binding characteristics of D2 receptors in the co-transfected COS-7 cells in contrast to the increased KH, KL and RH values found previously in rat striatal membranes after CGS 21680 treatment. The present findings indicate that transiently transfected A2a and D2 receptors in COS-7 cells have normal binding properties, but couple poorly to adenylyl cyclase, despite the presence of Gs protein and adenylyl cyclase in these cells. Our results also demonstrate that the previously reported interactions between A2a receptors and D2 receptors do not occur when only the receptor proteins are expressed in COS-7 cells, suggesting that the two receptor molecules do not interact directly to influence binding characteristics.Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe