Frequent loss of heterozygosity without loss of genetic material in acute myeloid leukemia with a normal karyotype

We performed a whole-genome loss of heterozygosity (LOH) analysis of 32 cases of acute myeloid leukemia with normal karyotype using high-density single nucleotide polymorphism arrays. LOH was found in 20% of cases. We identified two types of LOH: (i) interstitial, characterized by small deletions of genomic DNA (2-8 Mb), and (ii) terminal, involving large (30-90 Mb) telomeric regions. Surprisingly, terminal LOH occurred without loss of genetic material because of deletion of large chromosome regions and their substitution through the duplication of the corresponding regions from the homologous chromosomes (acquired partial uniparental disomy). (copyright) 2005 Wiley-Liss, Inc

Altered balance of helper T cells in Rai-/- mice

A number of immune related pathologies, such as autoimmune and allergic disorders, develop as the result of an imbalance among Th subsets. A Th1 bias has been consistently observed in autoimmunity both in man and in mouse, which has led to the notion that autoimmunity is a disease initiated by an abnormal polarization of CD4+ T cells towards the proinflammatory Th1 lineage. In addition to Th1 and Th2 cells, a third subset of effector Th cells producing IL-17 has recently been described and termed Th17. Th17 cells have been causally associated to the pathogenesis of human autoimmune diseases, of which multiple sclerosis is a striking example. Recent data have identified molecular adaptors as master regulators not only of T-cell activation, but also of Th cell development, highlighting these molecules as attractive targets for pharmacological manipulation. We have recently demonstrated that loss of Rai, a member of the Shc family expressed both in neuronal and in T cells, results in the development of systemic autoimmunity (Savino et al 2009). Since peripheral T cells from Rai -/- mice show an up-regulation of the Th17 cytokines we addressed the potential role of Rai in the signaling pathways controlling Th17 development and in the pathogenesis of multiple sclerosis. Our results indicate that Rai interferes with Th17 development by altering key steps of the signaling pathways triggered by TCR in combination with TGFβ and IL-6 and alter the severity of EAE disease

Hepatocyte odd protein shuttling (HOPS) is a bridging protein in the nucleophosmin-p19(Arf) network

Nucleophosmin (NPM), a ubiquitously and abundantly expressed protein, occurs in the nucleolus, shuttling between the nucleoplasm and cytoplasm. The NPM gene is mutated in almost 30% of human acute myeloid leukemia cells. NPM interacts with p53 and p19(Arf), directs localization of p19(Arf) in the nucleolus and protects the latter from degradation. Hepatocyte odd protein shuttling (HOPS) is also a ubiquitously expressed protein that moves between the nucleus and cytoplasm. Within the nucleus of resting cells, HOPS overexpression causes cell cycle arrest in G0/G1. HOPS knockdown causes centrosome hyperamplification leading to multinucleated cells and the formation of micronuclei. We demonstrate a direct interaction of HOPS with NPM and p19(Arf), resulting in a functionally active trimeric complex. NPM appeared to regulate HOPS half-life, which, in turn, stabilized p19(Arf) and controlled its localization in the nucleolus. These findings suggest that HOPS acts as a functional bridge in the interaction between NPM and p19(Arf), providing new mechanistic insight into how NPM and p19(Arf) will oppose tumor cell proliferatio

Activated protein C reverses epigenetically sustained p66Shc expression in plaque-associated macrophages in diabetes

Impaired activated protein C (aPC) generation is associated with atherosclerosis and diabetes mellitus. Diabetes-associated atherosclerosis is characterized by the hyperglycaemic memory, e.g., failure of disease improvement despite attenuation of hyperglycaemia. Therapies reversing the hyperglycaemic memory are lacking. Here we demonstrate that hyperglycaemia, but not hyperlipidaemia, induces the redox-regulator p66Shc and reactive oxygen species (ROS) in macrophages. p66Shc expression, ROS generation, and a pro-atherogenic phenotype are sustained despite restoring normoglycemic conditions. Inhibition of p66Shc abolishes this sustained pro-atherogenic phenotype, identifying p66Shc-dependent ROS in macrophages as a key mechanism conveying the hyperglycaemic memory. The p66Shc-associated hyperglycaemic memory can be reversed by aPC via protease-activated receptor-1 signalling. aPC reverses glucose-induced CpG hypomethylation within the p66Shc promoter by induction of the DNA methyltransferase-1 (DNMT1). Thus, epigenetically sustained p66Shc expression in plaque macrophages drives the hyperglycaemic memory, which-however-can be reversed by aPC. This establishes that reversal of the hyperglycaemic memory in diabetic atherosclerosis is feasible

p66Shc deficiency in the Eμ-TCL1 mouse model of chronic lymphocytic leukemia enhances leukemogenesis by altering the chemokine receptor landscape

The Shc family adaptor p66Shc acts as a negative regulator of proliferative and survival signals triggered by the B Cell Receptor and, by enhancing the production of reactive oxygen species, promotes oxidative stress-dependent apoptosis. Additionally, p66Shc controls the expression and function of chemokine receptors that regulate lymphocyte traffic. Chronic lymphocytic leukemia cells have a p66Shc expression defect which contributes to their extended survival and correlates with poor prognosis. We have analyzed the impact of p66Shc ablation on disease severity and progression in the mouse model of chronic lymphocytic leukemia E\u3bc-TCL1. We show that E\u3bc-TCL1/p66Shc-/- mice develop an aggressive disease that has an earlier onset, a higher incidence and leads to earlier death compared to E\u3bc-TCL1 mice. E\u3bc-TCL1/p66Shc-/- mice display substantial leukemic cell accumulation in both nodal and extranodal sites. The target organ selectivity correlates with an upregulation of chemokine receptors whose ligands are expressed therein. This also applies to chronic lymphocytic leukemia cells, where chemokine receptor expression and extent of organ infiltration were found to inversely correlate with their p66Shc expression levels. p66Shc expression declined with disease progression in E\u3bc-TCL1 mice and could be restored by treatment with the Bruton tyrosine kinase inhibitor Ibrutinib. Our results highlight p66Shc deficiency as an important factor in chronic lymphocytic leukemia progression and severity and underscore p66Shc expression as a relevant therapeutic target