http://www.jci.org/just-published en-us 2008 The American Society for Clinical Investigation http://www.jci.org/icons/banner/rss_title.gif http://content.jci.org Ana Silva, J. Andrés Yunes, Bruno A. Cardoso, Leila R. Martins, Patrícia Y. Jotta, Miguel Abecasis, Alexandre E. Nowill, Nick R. Leslie, Angelo A. Cardoso, Joao T. Barata http://www.jci.org/articles/view/34616 PTEN) gene leading to PTEN protein deletion and subsequent activation of the PI3K/Akt signaling pathway are common in cancer. Here we show that PTEN inactivation in human T cell acute lymphoblastic leukemia (T-ALL) cells is not always synonymous with PTEN gene lesions and diminished protein expression. Samples taken from patients with T-ALL at the time of diagnosis very frequently showed constitutive hyperactivation of the PI3K/Akt pathway. In contrast to immortalized cell lines, most primary T-ALL cells did not harbor PTEN gene alterations, displayed normal PTEN mRNA levels, and expressed higher PTEN protein levels than normal T cell precursors. However, PTEN overexpression was associated with decreased PTEN lipid phosphatase activity, resulting from casein kinase 2 (CK2) overexpression and hyperactivation. In addition, T-ALL cells had constitutively high levels of ROS, which can also downmodulate PTEN activity. Accordingly, both CK2 inhibitors and ROS scavengers restored PTEN activity and impaired PI3K/Akt signaling in T-ALL cells. Strikingly, inhibition of PI3K and/or CK2 promoted T-ALL cell death without affecting normal T cell precursors. Overall, our data indicate that T-ALL cells inactivate PTEN mostly in a nondeletional, posttranslational manner. Pharmacological manipulation of these mechanisms may open new avenues for T-ALL treatment. ]]> info:doi/10.1172/JCI34616 American Society for Clinical Investigation Milica Vukmanovic-Stejic, Elaine Agius, Nicola Booth, Padraic J. Dunne, Katie E. Lacy, John R. Reed, Toni O. Sobande, Steven Kissane, Mike Salmon, Malcolm H. Rustin, Arne N. Akbar http://www.jci.org/articles/view/35834 +CD25^hiFoxp3⁺ Tregs (nTregs) are highly proliferative in blood. However, the kinetics of their accumulation and proliferation during a localized antigen-specific T cell response is currently unknown. To explore this, we used a human experimental system whereby tuberculin purified protein derivative (PPD) was injected into the skin and the local T cell response analyzed over time. The numbers of both CD4⁺Foxp3^– (memory) and CD4⁺Foxp3⁺ (putative nTreg) T cells increased in parallel, with the 2 populations proliferating at the same relative rate. In contrast to CD4⁺Foxp3^– T cell populations, skin CD4⁺Foxp3⁺ T cells expressed typical Treg markers (i.e., they were CD25^hi, CD127^lo, CD27⁺, and CD39⁺) and did not synthesize IL-2 or IFN-γ after restimulation in vitro, indicating that they were not recently activated effector cells. To determine whether CD4⁺Foxp3⁺ T cells in skin could be induced from memory CD4⁺ T cells, we expanded skin-derived memory CD4⁺ T cells in vitro and anergized them. These cells expressed high levels of CD25 and Foxp3 and suppressed the proliferation of skin-derived responder T cells to PPD challenge. Our data therefore demonstrate that memory and CD4⁺ Treg populations are regulated in tandem during a secondary antigenic response. Furthermore, it is possible to isolate effector CD4⁺ T cell populations from inflamed tissues and manipulate them to generate Tregs with the potential to suppress inflammatory responses. ]]> info:doi/10.1172/JCI35834 American Society for Clinical Investigation Rusty L. Montgomery, Matthew J. Potthoff, Michael Haberland, Xiaoxia Qi, Satoshi Matsuzaki, Kenneth M. Humphries, James A. Richardson, Rhonda Bassel-Duby, Eric N. Olson http://www.jci.org/articles/view/35847 Hdac3 null allele. Although global deletion of Hdac3 resulted in lethality by E9.5, mice with a cardiac-specific deletion of Hdac3 survived until 3–4 months of age. At this time, they showed massive cardiac hypertrophy and upregulation of genes associated with fatty acid uptake, fatty acid oxidation, and electron transport/oxidative phosphorylation accompanied by fatty acid–induced myocardial lipid accumulation and elevated triglyceride levels. These abnormalities in cardiac metabolism can be attributed to excessive activity of the nuclear receptor PPARα. The phenotype associated with cardiac-specific Hdac3 gene deletion differs from that of all other Hdac gene mutations. These findings reveal a unique role for Hdac3 in maintenance of cardiac function and regulation of myocardial energy metabolism. ]]> info:doi/10.1172/JCI35847 American Society for Clinical Investigation Stephan Roux, Lionel Apetoh, Fanny Chalmin, Sylvain Ladoire, Grégoire Mignot, Pierre-Emmanuel Puig, Gregoire Lauvau, Laurence Zitvogel, François Martin, Bruno Chauffert, Hideo Yagita, Eric Solary, François Ghiringhelli http://www.jci.org/articles/view/35890 +CD25⁺ Tregs. The Tregs, in turn, inhibit the cytotoxic function of T cells and NK cells, but whether they have an effect on the cytotoxic function of tumor-infiltrating DCs (TIDCs) has not been determined. Here we have shown, in 2 rodent models of colon cancer, that CD4⁺CD25⁺ Tregs inhibit the ability of CD11b⁺ TIDCs to mediate TNF-related apoptosis-inducing ligand–induced (TRAIL-induced) tumor cell death. In both models of cancer, combination treatment with Mycobacterium bovis Bacillus Calmette-Guérin (BCG), which activates the innate immune system via TLR2, TLR4, and TLR9, and cyclophosphamide (CTX), which depletes Tregs, eradicated the tumors. Further analysis revealed that the treatment led to a marked increase in the number of CD11b⁺ TIDCs that killed the tumor cells via a TRAIL-dependent mechanism. Furthermore, acquisition of TRAIL expression by the CD11b⁺ TIDCs was induced by BCG and dependent on signaling through TLR2, TLR4, and TLR9. In vivo transfer of Tregs abrogated the ability of BCG to induce CD11b⁺ TIDCs to express TRAIL and thereby nullified the efficacy of the CTX-BCG treatment. Our data have therefore delineated what we believe to be a novel mechanism by which Tregs inhibit the antitumor immune response. ]]> info:doi/10.1172/JCI35890 American Society for Clinical Investigation Risto Kerkela, Lisa Kockeritz, Katrina MacAulay, Jibin Zhou, Bradley W. Doble, Cara Beahm, Sarah Greytak, Kathleen Woulfe, Chinmay M. Trivedi, James R. Woodgett, Jonathan A. Epstein, Thomas Force, Gordon S. Huggins http://www.jci.org/articles/view/36245 Gsk3b^–/– embryoid bodies. While GSK-3α–deficient mice were born without a cardiac phenotype, no live-born Gsk3b^–/– pups were recovered. The Gsk3b^–/– embryos had a double outlet RV, ventricular septal defects, and hypertrophic myopathy, with near obliteration of the ventricular cavities. The hypertrophic myopathy was caused by cardiomyocyte hyperproliferation without hypertrophy and was associated with increased expression and nuclear localization of three regulators of proliferation — GATA4, cyclin D1, and c-Myc. These studies, which we believe are the first in mammals to examine the role of GSK-3α and GSK-3β in the heart using loss-of-function approaches, implicate GSK-3β as a central regulator of embryonic cardiomyocyte proliferation and differentiation, as well as of outflow tract development. Although controversy over the teratogenic effects of lithium remains, our studies suggest that caution should be exercised in the use of newer, more potent drugs targeting GSK-3 in women of childbearing age. ]]> info:doi/10.1172/JCI36245 American Society for Clinical Investigation