Snai1 promotes ESC exit from the pluripotency by direct repression of self-renewal genes.

Although much is known about the pluripotency self-renewal circuitry, the molecular events that lead embryonic stem cells (ESCs) exit from pluripotency and begin differentiation are largely unknown. We found that the zinc finger transcription factor Snai1, involved in gastrulation and epithelial-mesenchymal transition, is already expressed in the inner cell mass of the preimplantation blastocysts. In ESCs, Snai1 does not respond to TGFß or BMP4 signaling but it is induced by retinoic acid treatment, which induces the binding, on the Snai1 promoter, of the retinoid receptors RARγ and RXRα, the dissociation of the Polycomb repressor complex 2 which results in the decrease of H3K27me3, and the increase of histone H3K4me3. Snai1 mediates the repression of pluripotency genes by binding directly to the promoters of Nanog, Nr5a2, Tcl1, c-Kit, and Tcfcp2l1. The transient activation of Snai1 in embryoid bodies induces the expression of the markers of all three germ layers. These results suggest that Snai1 is a key factor that triggers ESCs exit from the pluripotency state and initiate their differentiation processes.

Untangling the web of systemic autoinflammatory diseases.

The innate immune system is involved in the pathophysiology of systemic autoinflammatory diseases (SAIDs), an enlarging group of disorders caused by dysregulated production of proinflammatory cytokines, such as interleukin-1ß and tumor necrosis factor-α, in which autoreactive T-lymphocytes and autoantibodies are indeed absent. A widely deranged innate immunity leads to overactivity of proinflammatory cytokines and subsequent multisite inflammatory symptoms depicting various conditions, such as hereditary periodic fevers, granulomatous disorders, and pyogenic diseases, collectively described in this review. Further research should enhance our understanding of the genetics behind SAIDs, unearth triggers of inflammatory attacks, and result in improvement for their diagnosis and treatment.

c-ABL modulates MAP kinases activation downstream of VEGFR-2 signaling by direct phosphorylation of the adaptor proteins GRB2 and NCK1.

Vascular Endothelial Growth Factor-A (VEGF-A) is a key molecule in normal and tumor angiogenesis. This study addresses the role of c-ABL as a novel downstream target of VEGF-A in primary Human Umbilical Vein Endothelial Cells (HUVEC). On the basis of immunoprecipitation experiments, in vitro kinase assay and RNA interference, we demonstrate that VEGF-A induces the c-ABL kinase activity through the VEGF Receptor-2/Phosphatidylinositol-3-Kinase pathway. By treating HUVEC with the specific tyrosine kinase inhibitor STI571 and over-expressing a dominant negative c-ABL mutant, we show that the VEGF-A-activated c-ABL reduces the amplitude of Mitogen-Activated Protein Kinases (ERK1/2, JNKs and p38) activation in a dose-dependent manner by a negative feedback mechanism. By analysis of the adaptor proteins NCK1 and GRB2 mutants we further show that the negative loop on p38 is mediated by c-ABL phosphorylation at tyrosine 105 of the adaptor protein NCK1, while the phosphorylation at tyrosine 209 of GRB2 down-modulates ERK1/2 and JNKs signaling. These findings suggest that c-ABL function is to establish a correct and tightly controlled response of endothelial cells to VEGF-A during the angiogenic process.

Growth factor stimulation induces cell survival by c-Jun. ATF2-dependent activation of Bcl-XL.

Growth factor stimulation induces c-Jun-dependent survival of primary endothelial cells. However, the mechanism of c-Jun anti-apoptotic activity has not been identified. We here demonstrate that in response to growth factor treatment, primary human endothelial cells as well as mouse fibroblasts respond with an increased expression of c-Jun that forms a complex with ATF2. This complex activates the expression of the anti-apoptotic protein Bcl-X(L). By site-directed mutagenesis experiments, we identified two AP-1-binding sites located within the proximal promoter of the Bcl-X gene. Site-directed mutagenesis demonstrated that these AP-1 sites are required for the transcriptional activation of the promoter. Chromatin immunoprecipitation experiments show that in response to growth factor treatment, the heterodimer c-Jun.ATF2 binds to these functional AP-1 sites. Silencing of either c-Jun or ATF2 demonstrated that both nuclear factors are required for the activation of the proximal Bcl-X promoter. Taken together, our experiments provide evidence that growth factor-independent signaling pathways converge in the formation of an active c-Jun.AFT2 dimer, which induces the expression of the anti-apoptotic factor Bcl-X(L) that mediates a pro-survival response.

Corticotropin releasing hormone and Urocortin 2 activate inflammatory pathways in cultured trophoblast cell lines.

OBJECTIVE: Embryo implantation and parturition are recognized as inflammatory events involving endocrine and immune system. NF-kB and MAPK are two transcription factor families involved in inflammation. A possible role of neuroendocrine mechanism in early pregnancy and delivery was proposed for the neuropeptides related to corticotropin releasing hormones (CRH), named Urocortins (Ucns). Experimental and clinical studies support a role for CRH, Ucn, Ucn2 and Ucn3 in the endocrine/immune modulation of inflammation in human trophoblast; however the intracellular mechanisms are not yet recognized. The aim of the present study was to evaluate which of these neuropeptides modulate NF-kB or MAPKs pathways. STUDY DESIGN: In Jeg-3 placental cell line the effect of CRH, Ucn, Ucn2 or Ucn3 on NF-kB and MAPKs pathways were evaluated using Western blot analysis. RESULTS: CRH induced the phosphorylation of MAPK subunits; Ucn2 was able to induce the phosphorylation of both NF-kB and MAPK subunits. Ucn and Ucn3 had no effects on these pathways. CONCLUSIONS: These data provide novel information on inflammatory process in trophoblast cells: Ucn2 is a potent pro-inflammatory neuropeptide via NF-kB and MAPK pathways and CRH via MAPK, and CRH and Ucn2 network participates in the inflammatory mechanisms of pregnancy and parturition.

The labyrinth of autoinflammatory disorders: a snapshot on the activity of a third-level center in Italy.

Autoinflammatory disorders (AIDs) are a novel class of diseases elicited by mutations in genes regulating the homeostasis of innate immune complexes, named inflammasomes, which lead to uncontrolled oversecretion of the proinflammatory cytokine interleukin-1ß. Protean inflammatory symptoms are variably associated with periodic fever, depicting multiple specific conditions. Childhood is usually the lifetime in which most hereditary AIDs start, though still a relevant number of patients may experience a delayed disease onset and receive a definite diagnosis during adulthood. As a major referral laboratory for patients with recurrent fevers, we have tested samples from 787 patients in the period September 2007-March 2014, with a total of 1,328 AID-related genes evaluated and a gene/patient ratio of 1.69. In this report, we describe our experience in the clinical approach to AIDs, highlight the most striking differences between child and adult-onset AIDs, and shed an eye-opening insight into their diagnostic process.

Key facts and hot spots on tumor necrosis factor receptor-associated periodic syndrome.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS), formerly known as familial Hibernian fever, is the most common autosomal dominant autoinflammatory disease, resulting from mutations in the TNFRSF1A gene, encoding the 55-kD tumor necrosis factor receptor. The pathophysiologic mechanism of TRAPS remains ambiguous and only partially explained. The onset age of the syndrome is variable and the clinical scenery is characterized by recurrent episodes of high-grade fever that typically lasts 1-3 weeks, associated with migrating myalgia, pseudocellulitis, diffuse abdominal pain, appendicitis-like findings, ocular inflammatory signs, and risk of long-term amyloidosis. Fever episodes are responsive to high-dose corticosteroids, but different classes of drugs have been reported to be ineffective. The use of etanercept is unable to control systemic inflammation, while interleukin-1 blockade has been shown as effective in the control of disease activity in many patients reported so far.